[PATCH] ecryptfs: fs/Makefile and fs/Kconfig

eCryptfs is a stacked cryptographic filesystem for Linux. It is derived from
Erez Zadok's Cryptfs, implemented through the FiST framework for generating
stacked filesystems. eCryptfs extends Cryptfs to provide advanced key
management and policy features. eCryptfs stores cryptographic metadata in the
header of each file written, so that encrypted files can be copied between
hosts; the file will be decryptable with the proper key, and there is no need
to keep track of any additional information aside from what is already in the
encrypted file itself.

[[e-mail]: updates for ongoing API changes]
[[e-mail]: cleanups]
[[e-mail]: alpha build fix]
[[e-mail]: cleanups]
[[e-mail]: inode-diet updates]
[[e-mail]: generic_file_*_read/write() interface updates]
[[e-mail]: printk format fixes]
[[e-mail]: make slab creation and teardown table-driven]
Signed-off-by: Phillip Hellewell <[e-mail]>
Signed-off-by: Michael Halcrow <[e-mail]>
Signed-off-by: Erez Zadok <[e-mail]>
Signed-off-by: Adrian Bunk <[e-mail]>
Signed-off-by: Stephan Mueller <[e-mail]>
Signed-off-by: "Theodore Ts'o" <[e-mail]>
Signed-off-by: Badari Pulavarty <[e-mail]>
Signed-off-by: Randy Dunlap <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/ecryptfs.txt

···
+eCryptfs: A stacked cryptographic filesystem for Linux
+
+eCryptfs is free software. Please see the file COPYING for details.
+For documentation, please see the files in the doc/ subdirectory.  For
+building and installation instructions please see the INSTALL file.
+
+Maintainer: Phillip Hellewell
+Lead developer: Michael A. Halcrow <[e-mail]>
+Developers: Michael C. Thompson
+            Kent Yoder
+Web Site: http://ecryptfs.sf.net
+
+This software is currently undergoing development. Make sure to
+maintain a backup copy of any data you write into eCryptfs.
+
+eCryptfs requires the userspace tools downloadable from the
+SourceForge site:
+
+http://sourceforge.net/projects/ecryptfs/
+
+Userspace requirements include:
+ - David Howells' userspace keyring headers and libraries (version
+   1.0 or higher), obtainable from
+   http://people.redhat.com/~dhowells/keyutils/
+ - Libgcrypt
+
+
+NOTES
+
+In the beta/experimental releases of eCryptfs, when you upgrade
+eCryptfs, you should copy the files to an unencrypted location and
+then copy the files back into the new eCryptfs mount to migrate the
+files.
+
+
+MOUNT-WIDE PASSPHRASE
+
+Create a new directory into which eCryptfs will write its encrypted
+files (i.e., /root/crypt).  Then, create the mount point directory
+(i.e., /mnt/crypt).  Now it's time to mount eCryptfs:
+
+mount -t ecryptfs /root/crypt /mnt/crypt
+
+You should be prompted for a passphrase and a salt (the salt may be
+blank).
+
+Try writing a new file:
+
+echo "Hello, World" > /mnt/crypt/hello.txt
+
+The operation will complete.  Notice that there is a new file in
+/root/crypt that is at least 12288 bytes in size (depending on your
+host page size).  This is the encrypted underlying file for what you
+just wrote.  To test reading, from start to finish, you need to clear
+the user session keyring:
+
+keyctl clear @u
+
+Then umount /mnt/crypt and mount again per the instructions given
+above.
+
+cat /mnt/crypt/hello.txt
+
+
+NOTES
+
+eCryptfs version 0.1 should only be mounted on (1) empty directories
+or (2) directories containing files only created by eCryptfs. If you
+mount a directory that has pre-existing files not created by eCryptfs,
+then behavior is undefined. Do not run eCryptfs in higher verbosity
+levels unless you are doing so for the sole purpose of debugging or
+development, since secret values will be written out to the system log
+in that case.
+
+
+Mike Halcrow
[e-mail]

MAINTAINERS

···
 W:	http://ebtables.sourceforge.net/
 S:	Maintained
 
+ECRYPT FILE SYSTEM
+P:	Mike Halcrow, Phillip Hellewell
+M:	[e-mail], [e-mail]
+L:	[e-mail]
+W:	http://ecryptfs.sourceforge.net/
+S:	Supported
+
 EDAC-CORE
 P:	Doug Thompson
 M:	[e-mail]

fs/Kconfig

···
 	  To compile this file system support as a module, choose M here: the
 	  module will be called affs.  If unsure, say N.
 
+config ECRYPT_FS
+	tristate "eCrypt filesystem layer support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && KEYS && CRYPTO
+	help
+	  Encrypted filesystem that operates on the VFS layer.  See
+	  <file:Documentation/ecryptfs.txt> to learn more about
+	  eCryptfs.  Userspace components are required and can be
+	  obtained from <http://ecryptfs.sf.net>.
+
+	  To compile this file system support as a module, choose M here: the
+	  module will be called ecryptfs.
+
 config HFS_FS
 	tristate "Apple Macintosh file system support (EXPERIMENTAL)"
 	depends on BLOCK && EXPERIMENTAL

fs/Makefile

···
 obj-$(CONFIG_ISO9660_FS)	+= isofs/
 obj-$(CONFIG_HFSPLUS_FS)	+= hfsplus/ # Before hfs to find wrapped HFS+
 obj-$(CONFIG_HFS_FS)		+= hfs/
+obj-$(CONFIG_ECRYPT_FS)		+= ecryptfs/
 obj-$(CONFIG_VXFS_FS)		+= freevxfs/
 obj-$(CONFIG_NFS_FS)		+= nfs/
 obj-$(CONFIG_EXPORTFS)		+= exportfs/

fs/ecryptfs/Makefile

···
+#
+# Makefile for the Linux 2.6 eCryptfs
+#
+
+obj-$(CONFIG_ECRYPT_FS) += ecryptfs.o
+
+ecryptfs-objs := dentry.o file.o inode.o main.o super.o mmap.o crypto.o keystore.o debug.o

fs/ecryptfs/crypto.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2004 Erez Zadok
+ * Copyright (C) 2001-2004 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *   		Michael C. Thompson <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/random.h>
+#include <linux/compiler.h>
+#include <linux/key.h>
+#include <linux/namei.h>
+#include <linux/crypto.h>
+#include <linux/file.h>
+#include <linux/scatterlist.h>
+#include "ecryptfs_kernel.h"
+
+static int
+ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
+			     struct page *dst_page, int dst_offset,
+			     struct page *src_page, int src_offset, int size,
+			     unsigned char *iv);
+static int
+ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
+			     struct page *dst_page, int dst_offset,
+			     struct page *src_page, int src_offset, int size,
+			     unsigned char *iv);
+
+/**
+ * ecryptfs_to_hex
+ * @dst: Buffer to take hex character representation of contents of
+ *       src; must be at least of size (src_size * 2)
+ * @src: Buffer to be converted to a hex string respresentation
+ * @src_size: number of bytes to convert
+ */
+void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
+{
+	int x;
+
+	for (x = 0; x < src_size; x++)
+		sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
+}
+
+/**
+ * ecryptfs_from_hex
+ * @dst: Buffer to take the bytes from src hex; must be at least of
+ *       size (src_size / 2)
+ * @src: Buffer to be converted from a hex string respresentation to raw value
+ * @dst_size: size of dst buffer, or number of hex characters pairs to convert
+ */
+void ecryptfs_from_hex(char *dst, char *src, int dst_size)
+{
+	int x;
+	char tmp[3] = { 0, };
+
+	for (x = 0; x < dst_size; x++) {
+		tmp[0] = src[x * 2];
+		tmp[1] = src[x * 2 + 1];
+		dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
+	}
+}
+
+/**
+ * ecryptfs_calculate_md5 - calculates the md5 of @src
+ * @dst: Pointer to 16 bytes of allocated memory
+ * @crypt_stat: Pointer to crypt_stat struct for the current inode
+ * @src: Data to be md5'd
+ * @len: Length of @src
+ *
+ * Uses the allocated crypto context that crypt_stat references to
+ * generate the MD5 sum of the contents of src.
+ */
+static int ecryptfs_calculate_md5(char *dst,
+				  struct ecryptfs_crypt_stat *crypt_stat,
+				  char *src, int len)
+{
+	int rc = 0;
+	struct scatterlist sg;
+
+	mutex_lock(&crypt_stat->cs_md5_tfm_mutex);
+	sg_init_one(&sg, (u8 *)src, len);
+	if (!crypt_stat->md5_tfm) {
+		crypt_stat->md5_tfm =
+			crypto_alloc_tfm("md5", CRYPTO_TFM_REQ_MAY_SLEEP);
+		if (!crypt_stat->md5_tfm) {
+			rc = -ENOMEM;
+			ecryptfs_printk(KERN_ERR, "Error attempting to "
+					"allocate crypto context\n");
+			goto out;
+		}
+	}
+	crypto_digest_init(crypt_stat->md5_tfm);
+	crypto_digest_update(crypt_stat->md5_tfm, &sg, 1);
+	crypto_digest_final(crypt_stat->md5_tfm, dst);
+	mutex_unlock(&crypt_stat->cs_md5_tfm_mutex);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_derive_iv
+ * @iv: destination for the derived iv vale
+ * @crypt_stat: Pointer to crypt_stat struct for the current inode
+ * @offset: Offset of the page whose's iv we are to derive
+ *
+ * Generate the initialization vector from the given root IV and page
+ * offset.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
+			      pgoff_t offset)
+{
+	int rc = 0;
+	char dst[MD5_DIGEST_SIZE];
+	char src[ECRYPTFS_MAX_IV_BYTES + 16];
+
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "root iv:\n");
+		ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
+	}
+	/* TODO: It is probably secure to just cast the least
+	 * significant bits of the root IV into an unsigned long and
+	 * add the offset to that rather than go through all this
+	 * hashing business. -Halcrow */
+	memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
+	memset((src + crypt_stat->iv_bytes), 0, 16);
+	snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset);
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "source:\n");
+		ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
+	}
+	rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
+				    (crypt_stat->iv_bytes + 16));
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
+				"MD5 while generating IV for a page\n");
+		goto out;
+	}
+	memcpy(iv, dst, crypt_stat->iv_bytes);
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
+		ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_init_crypt_stat
+ * @crypt_stat: Pointer to the crypt_stat struct to initialize.
+ *
+ * Initialize the crypt_stat structure.
+ */
+void
+ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
+	mutex_init(&crypt_stat->cs_mutex);
+	mutex_init(&crypt_stat->cs_tfm_mutex);
+	mutex_init(&crypt_stat->cs_md5_tfm_mutex);
+	ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED);
+}
+
+/**
+ * ecryptfs_destruct_crypt_stat
+ * @crypt_stat: Pointer to the crypt_stat struct to initialize.
+ *
+ * Releases all memory associated with a crypt_stat struct.
+ */
+void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	if (crypt_stat->tfm)
+		crypto_free_tfm(crypt_stat->tfm);
+	if (crypt_stat->md5_tfm)
+		crypto_free_tfm(crypt_stat->md5_tfm);
+	memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
+}
+
+void ecryptfs_destruct_mount_crypt_stat(
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	if (mount_crypt_stat->global_auth_tok_key)
+		key_put(mount_crypt_stat->global_auth_tok_key);
+	if (mount_crypt_stat->global_key_tfm)
+		crypto_free_tfm(mount_crypt_stat->global_key_tfm);
+	memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
+}
+
+/**
+ * virt_to_scatterlist
+ * @addr: Virtual address
+ * @size: Size of data; should be an even multiple of the block size
+ * @sg: Pointer to scatterlist array; set to NULL to obtain only
+ *      the number of scatterlist structs required in array
+ * @sg_size: Max array size
+ *
+ * Fills in a scatterlist array with page references for a passed
+ * virtual address.
+ *
+ * Returns the number of scatterlist structs in array used
+ */
+int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
+			int sg_size)
+{
+	int i = 0;
+	struct page *pg;
+	int offset;
+	int remainder_of_page;
+
+	while (size > 0 && i < sg_size) {
+		pg = virt_to_page(addr);
+		offset = offset_in_page(addr);
+		if (sg) {
+			sg[i].page = pg;
+			sg[i].offset = offset;
+		}
+		remainder_of_page = PAGE_CACHE_SIZE - offset;
+		if (size >= remainder_of_page) {
+			if (sg)
+				sg[i].length = remainder_of_page;
+			addr += remainder_of_page;
+			size -= remainder_of_page;
+		} else {
+			if (sg)
+				sg[i].length = size;
+			addr += size;
+			size = 0;
+		}
+		i++;
+	}
+	if (size > 0)
+		return -ENOMEM;
+	return i;
+}
+
+/**
+ * encrypt_scatterlist
+ * @crypt_stat: Pointer to the crypt_stat struct to initialize.
+ * @dest_sg: Destination of encrypted data
+ * @src_sg: Data to be encrypted
+ * @size: Length of data to be encrypted
+ * @iv: iv to use during encryption
+ *
+ * Returns the number of bytes encrypted; negative value on error
+ */
+static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
+			       struct scatterlist *dest_sg,
+			       struct scatterlist *src_sg, int size,
+			       unsigned char *iv)
+{
+	int rc = 0;
+
+	BUG_ON(!crypt_stat || !crypt_stat->tfm
+	       || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+				       ECRYPTFS_STRUCT_INITIALIZED));
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
+				crypt_stat->key_size);
+		ecryptfs_dump_hex(crypt_stat->key,
+				  crypt_stat->key_size);
+	}
+	/* Consider doing this once, when the file is opened */
+	mutex_lock(&crypt_stat->cs_tfm_mutex);
+	rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key,
+				  crypt_stat->key_size);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
+				rc);
+		mutex_unlock(&crypt_stat->cs_tfm_mutex);
+		rc = -EINVAL;
+		goto out;
+	}
+	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
+	crypto_cipher_encrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, iv);
+	mutex_unlock(&crypt_stat->cs_tfm_mutex);
+out:
+	return rc;
+}
+
+static void
+ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
+					 int *byte_offset,
+					 struct ecryptfs_crypt_stat *crypt_stat,
+					 unsigned long extent_num)
+{
+	unsigned long lower_extent_num;
+	int extents_occupied_by_headers_at_front;
+	int bytes_occupied_by_headers_at_front;
+	int extent_offset;
+	int extents_per_page;
+
+	bytes_occupied_by_headers_at_front =
+		( crypt_stat->header_extent_size
+		  * crypt_stat->num_header_extents_at_front );
+	extents_occupied_by_headers_at_front =
+		( bytes_occupied_by_headers_at_front
+		  / crypt_stat->extent_size );
+	lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
+	extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
+	(*lower_page_idx) = lower_extent_num / extents_per_page;
+	extent_offset = lower_extent_num % extents_per_page;
+	(*byte_offset) = extent_offset * crypt_stat->extent_size;
+	ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = "
+			"[%d]\n", crypt_stat->header_extent_size);
+	ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
+			"num_header_extents_at_front = [%d]\n",
+			crypt_stat->num_header_extents_at_front);
+	ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
+			"front = [%d]\n", extents_occupied_by_headers_at_front);
+	ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
+			lower_extent_num);
+	ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
+			extents_per_page);
+	ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
+			(*lower_page_idx));
+	ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
+			extent_offset);
+	ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
+			(*byte_offset));
+}
+
+static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
+				   struct page *lower_page,
+				   struct inode *lower_inode,
+				   int byte_offset_in_page, int bytes_to_write)
+{
+	int rc = 0;
+
+	if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
+		rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
+						ctx->param.lower_file,
+						byte_offset_in_page,
+						bytes_to_write);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error calling lower "
+					"commit; rc = [%d]\n", rc);
+			goto out;
+		}
+	} else {
+		rc = ecryptfs_writepage_and_release_lower_page(lower_page,
+							       lower_inode,
+							       ctx->param.wbc);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error calling lower "
+					"writepage(); rc = [%d]\n", rc);
+			goto out;
+		}
+	}
+out:
+	return rc;
+}
+
+static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
+				 struct page **lower_page,
+				 struct inode *lower_inode,
+				 unsigned long lower_page_idx,
+				 int byte_offset_in_page)
+{
+	int rc = 0;
+
+	if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
+		/* TODO: Limit this to only the data extents that are
+		 * needed */
+		rc = ecryptfs_get_lower_page(lower_page, lower_inode,
+					     ctx->param.lower_file,
+					     lower_page_idx,
+					     byte_offset_in_page,
+					     (PAGE_CACHE_SIZE
+					      - byte_offset_in_page));
+		if (rc) {
+			ecryptfs_printk(
+				KERN_ERR, "Error attempting to grab, map, "
+				"and prepare_write lower page with index "
+				"[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
+			goto out;
+		}
+	} else {
+		rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL,
+						      lower_inode,
+						      lower_page_idx);
+		if (rc) {
+			ecryptfs_printk(
+				KERN_ERR, "Error attempting to grab and map "
+				"lower page with index [0x%.16x]; rc = [%d]\n",
+				lower_page_idx, rc);
+			goto out;
+		}
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_encrypt_page
+ * @ctx: The context of the page
+ *
+ * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
+ * that eCryptfs pages may straddle the lower pages -- for instance,
+ * if the file was created on a machine with an 8K page size
+ * (resulting in an 8K header), and then the file is copied onto a
+ * host with a 32K page size, then when reading page 0 of the eCryptfs
+ * file, 24K of page 0 of the lower file will be read and decrypted,
+ * and then 8K of page 1 of the lower file will be read and decrypted.
+ *
+ * The actual operations performed on each page depends on the
+ * contents of the ecryptfs_page_crypt_context struct.
+ *
+ * Returns zero on success; negative on error
+ */
+int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
+{
+	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
+	unsigned long base_extent;
+	unsigned long extent_offset = 0;
+	unsigned long lower_page_idx = 0;
+	unsigned long prior_lower_page_idx = 0;
+	struct page *lower_page;
+	struct inode *lower_inode;
+	struct ecryptfs_inode_info *inode_info;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	int rc = 0;
+	int lower_byte_offset = 0;
+	int orig_byte_offset = 0;
+	int num_extents_per_page;
+#define ECRYPTFS_PAGE_STATE_UNREAD    0
+#define ECRYPTFS_PAGE_STATE_READ      1
+#define ECRYPTFS_PAGE_STATE_MODIFIED  2
+#define ECRYPTFS_PAGE_STATE_WRITTEN   3
+	int page_state;
+
+	lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
+	inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
+	crypt_stat = &inode_info->crypt_stat;
+	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
+		rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
+						 ctx->param.lower_file);
+		if (rc)
+			ecryptfs_printk(KERN_ERR, "Error attempting to copy "
+					"page at index [0x%.16x]\n",
+					ctx->page->index);
+		goto out;
+	}
+	num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
+	base_extent = (ctx->page->index * num_extents_per_page);
+	page_state = ECRYPTFS_PAGE_STATE_UNREAD;
+	while (extent_offset < num_extents_per_page) {
+		ecryptfs_extent_to_lwr_pg_idx_and_offset(
+			&lower_page_idx, &lower_byte_offset, crypt_stat,
+			(base_extent + extent_offset));
+		if (prior_lower_page_idx != lower_page_idx
+		    && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
+			rc = ecryptfs_write_out_page(ctx, lower_page,
+						     lower_inode,
+						     orig_byte_offset,
+						     (PAGE_CACHE_SIZE
+						      - orig_byte_offset));
+			if (rc) {
+				ecryptfs_printk(KERN_ERR, "Error attempting "
+						"to write out page; rc = [%d]"
+						"\n", rc);
+				goto out;
+			}
+			page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
+		}
+		if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
+		    || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
+			rc = ecryptfs_read_in_page(ctx, &lower_page,
+						   lower_inode, lower_page_idx,
+						   lower_byte_offset);
+			if (rc) {
+				ecryptfs_printk(KERN_ERR, "Error attempting "
+						"to read in lower page with "
+						"index [0x%.16x]; rc = [%d]\n",
+						lower_page_idx, rc);
+				goto out;
+			}
+			orig_byte_offset = lower_byte_offset;
+			prior_lower_page_idx = lower_page_idx;
+			page_state = ECRYPTFS_PAGE_STATE_READ;
+		}
+		BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
+			 || page_state == ECRYPTFS_PAGE_STATE_READ));
+		rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
+					(base_extent + extent_offset));
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error attempting to "
+					"derive IV for extent [0x%.16x]; "
+					"rc = [%d]\n",
+					(base_extent + extent_offset), rc);
+			goto out;
+		}
+		if (unlikely(ecryptfs_verbosity > 0)) {
+			ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
+					"with iv:\n");
+			ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
+			ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
+					"encryption:\n");
+			ecryptfs_dump_hex((char *)
+					  (page_address(ctx->page)
+					   + (extent_offset
+					      * crypt_stat->extent_size)), 8);
+		}
+		rc = ecryptfs_encrypt_page_offset(
+			crypt_stat, lower_page, lower_byte_offset, ctx->page,
+			(extent_offset * crypt_stat->extent_size),
+			crypt_stat->extent_size, extent_iv);
+		ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
+				"rc = [%d]\n",
+				(base_extent + extent_offset), rc);
+		if (unlikely(ecryptfs_verbosity > 0)) {
+			ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
+					"encryption:\n");
+			ecryptfs_dump_hex((char *)(page_address(lower_page)
+						   + lower_byte_offset), 8);
+		}
+		page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
+		extent_offset++;
+	}
+	BUG_ON(orig_byte_offset != 0);
+	rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
+				     (lower_byte_offset
+				      + crypt_stat->extent_size));
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to write out "
+				"page; rc = [%d]\n", rc);
+				goto out;
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_decrypt_page
+ * @file: The ecryptfs file
+ * @page: The page in ecryptfs to decrypt
+ *
+ * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
+ * that eCryptfs pages may straddle the lower pages -- for instance,
+ * if the file was created on a machine with an 8K page size
+ * (resulting in an 8K header), and then the file is copied onto a
+ * host with a 32K page size, then when reading page 0 of the eCryptfs
+ * file, 24K of page 0 of the lower file will be read and decrypted,
+ * and then 8K of page 1 of the lower file will be read and decrypted.
+ *
+ * Returns zero on success; negative on error
+ */
+int ecryptfs_decrypt_page(struct file *file, struct page *page)
+{
+	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
+	unsigned long base_extent;
+	unsigned long extent_offset = 0;
+	unsigned long lower_page_idx = 0;
+	unsigned long prior_lower_page_idx = 0;
+	struct page *lower_page;
+	char *lower_page_virt = NULL;
+	struct inode *lower_inode;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	int rc = 0;
+	int byte_offset;
+	int num_extents_per_page;
+	int page_state;
+
+	crypt_stat = &(ecryptfs_inode_to_private(
+			       page->mapping->host)->crypt_stat);
+	lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
+	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
+		rc = ecryptfs_do_readpage(file, page, page->index);
+		if (rc)
+			ecryptfs_printk(KERN_ERR, "Error attempting to copy "
+					"page at index [0x%.16x]\n",
+					page->index);
+		goto out;
+	}
+	num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
+	base_extent = (page->index * num_extents_per_page);
+	lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
+					   SLAB_KERNEL);
+	if (!lower_page_virt) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
+				"lower page(s)\n");
+		goto out;
+	}
+	lower_page = virt_to_page(lower_page_virt);
+	page_state = ECRYPTFS_PAGE_STATE_UNREAD;
+	while (extent_offset < num_extents_per_page) {
+		ecryptfs_extent_to_lwr_pg_idx_and_offset(
+			&lower_page_idx, &byte_offset, crypt_stat,
+			(base_extent + extent_offset));
+		if (prior_lower_page_idx != lower_page_idx
+		    || page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
+			rc = ecryptfs_do_readpage(file, lower_page,
+						  lower_page_idx);
+			if (rc) {
+				ecryptfs_printk(KERN_ERR, "Error reading "
+						"lower encrypted page; rc = "
+						"[%d]\n", rc);
+				goto out;
+			}
+			prior_lower_page_idx = lower_page_idx;
+			page_state = ECRYPTFS_PAGE_STATE_READ;
+		}
+		rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
+					(base_extent + extent_offset));
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error attempting to "
+					"derive IV for extent [0x%.16x]; rc = "
+					"[%d]\n",
+					(base_extent + extent_offset), rc);
+			goto out;
+		}
+		if (unlikely(ecryptfs_verbosity > 0)) {
+			ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
+					"with iv:\n");
+			ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
+			ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
+					"decryption:\n");
+			ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
+		}
+		rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
+						  (extent_offset
+						   * crypt_stat->extent_size),
+						  lower_page, byte_offset,
+						  crypt_stat->extent_size,
+						  extent_iv);
+		if (rc != crypt_stat->extent_size) {
+			ecryptfs_printk(KERN_ERR, "Error attempting to "
+					"decrypt extent [0x%.16x]\n",
+					(base_extent + extent_offset));
+			goto out;
+		}
+		rc = 0;
+		if (unlikely(ecryptfs_verbosity > 0)) {
+			ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
+					"decryption:\n");
+			ecryptfs_dump_hex((char *)(page_address(page)
+						   + byte_offset), 8);
+		}
+		extent_offset++;
+	}
+out:
+	if (lower_page_virt)
+		kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
+	return rc;
+}
+
+/**
+ * decrypt_scatterlist
+ *
+ * Returns the number of bytes decrypted; negative value on error
+ */
+static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
+			       struct scatterlist *dest_sg,
+			       struct scatterlist *src_sg, int size,
+			       unsigned char *iv)
+{
+	int rc = 0;
+
+	/* Consider doing this once, when the file is opened */
+	mutex_lock(&crypt_stat->cs_tfm_mutex);
+	rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key,
+				  crypt_stat->key_size);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
+				rc);
+		mutex_unlock(&crypt_stat->cs_tfm_mutex);
+		rc = -EINVAL;
+		goto out;
+	}
+	ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
+	rc = crypto_cipher_decrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size,
+				      iv);
+	mutex_unlock(&crypt_stat->cs_tfm_mutex);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
+				rc);
+		goto out;
+	}
+	rc = size;
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_encrypt_page_offset
+ *
+ * Returns the number of bytes encrypted
+ */
+static int
+ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
+			     struct page *dst_page, int dst_offset,
+			     struct page *src_page, int src_offset, int size,
+			     unsigned char *iv)
+{
+	struct scatterlist src_sg, dst_sg;
+
+	src_sg.page = src_page;
+	src_sg.offset = src_offset;
+	src_sg.length = size;
+	dst_sg.page = dst_page;
+	dst_sg.offset = dst_offset;
+	dst_sg.length = size;
+	return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
+}
+
+/**
+ * ecryptfs_decrypt_page_offset
+ *
+ * Returns the number of bytes decrypted
+ */
+static int
+ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
+			     struct page *dst_page, int dst_offset,
+			     struct page *src_page, int src_offset, int size,
+			     unsigned char *iv)
+{
+	struct scatterlist src_sg, dst_sg;
+
+	src_sg.page = src_page;
+	src_sg.offset = src_offset;
+	src_sg.length = size;
+	dst_sg.page = dst_page;
+	dst_sg.offset = dst_offset;
+	dst_sg.length = size;
+	return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
+}
+
+#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
+
+/**
+ * ecryptfs_init_crypt_ctx
+ * @crypt_stat: Uninitilized crypt stats structure
+ *
+ * Initialize the crypto context.
+ *
+ * TODO: Performance: Keep a cache of initialized cipher contexts;
+ * only init if needed
+ */
+int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int rc = -EINVAL;
+
+	if (!crypt_stat->cipher) {
+		ecryptfs_printk(KERN_ERR, "No cipher specified\n");
+		goto out;
+	}
+	ecryptfs_printk(KERN_DEBUG,
+			"Initializing cipher [%s]; strlen = [%d]; "
+			"key_size_bits = [%d]\n",
+			crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
+			crypt_stat->key_size << 3);
+	if (crypt_stat->tfm) {
+		rc = 0;
+		goto out;
+	}
+	mutex_lock(&crypt_stat->cs_tfm_mutex);
+	crypt_stat->tfm = crypto_alloc_tfm(crypt_stat->cipher,
+					   ECRYPTFS_DEFAULT_CHAINING_MODE
+					   | CRYPTO_TFM_REQ_WEAK_KEY);
+	mutex_unlock(&crypt_stat->cs_tfm_mutex);
+	if (!crypt_stat->tfm) {
+		ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
+				"Error initializing cipher [%s]\n",
+				crypt_stat->cipher);
+		goto out;
+	}
+	rc = 0;
+out:
+	return rc;
+}
+
+static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int extent_size_tmp;
+
+	crypt_stat->extent_mask = 0xFFFFFFFF;
+	crypt_stat->extent_shift = 0;
+	if (crypt_stat->extent_size == 0)
+		return;
+	extent_size_tmp = crypt_stat->extent_size;
+	while ((extent_size_tmp & 0x01) == 0) {
+		extent_size_tmp >>= 1;
+		crypt_stat->extent_mask <<= 1;
+		crypt_stat->extent_shift++;
+	}
+}
+
+void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	/* Default values; may be overwritten as we are parsing the
+	 * packets. */
+	crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
+	set_extent_mask_and_shift(crypt_stat);
+	crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
+	if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
+		crypt_stat->header_extent_size =
+			ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
+	} else
+		crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
+	crypt_stat->num_header_extents_at_front = 1;
+}
+
+/**
+ * ecryptfs_compute_root_iv
+ * @crypt_stats
+ *
+ * On error, sets the root IV to all 0's.
+ */
+int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int rc = 0;
+	char dst[MD5_DIGEST_SIZE];
+
+	BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
+	BUG_ON(crypt_stat->iv_bytes <= 0);
+	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_WARNING, "Session key not valid; "
+				"cannot generate root IV\n");
+		goto out;
+	}
+	rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
+				    crypt_stat->key_size);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
+				"MD5 while generating root IV\n");
+		goto out;
+	}
+	memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
+out:
+	if (rc) {
+		memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
+		ECRYPTFS_SET_FLAG(crypt_stat->flags,
+				  ECRYPTFS_SECURITY_WARNING);
+	}
+	return rc;
+}
+
+static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	get_random_bytes(crypt_stat->key, crypt_stat->key_size);
+	ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
+	ecryptfs_compute_root_iv(crypt_stat);
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
+		ecryptfs_dump_hex(crypt_stat->key,
+				  crypt_stat->key_size);
+	}
+}
+
+/**
+ * ecryptfs_set_default_crypt_stat_vals
+ * @crypt_stat
+ *
+ * Default values in the event that policy does not override them.
+ */
+static void ecryptfs_set_default_crypt_stat_vals(
+	struct ecryptfs_crypt_stat *crypt_stat,
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	ecryptfs_set_default_sizes(crypt_stat);
+	strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
+	crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
+	ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
+	crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
+	crypt_stat->mount_crypt_stat = mount_crypt_stat;
+}
+
+/**
+ * ecryptfs_new_file_context
+ * @ecryptfs_dentry
+ *
+ * If the crypto context for the file has not yet been established,
+ * this is where we do that.  Establishing a new crypto context
+ * involves the following decisions:
+ *  - What cipher to use?
+ *  - What set of authentication tokens to use?
+ * Here we just worry about getting enough information into the
+ * authentication tokens so that we know that they are available.
+ * We associate the available authentication tokens with the new file
+ * via the set of signatures in the crypt_stat struct.  Later, when
+ * the headers are actually written out, we may again defer to
+ * userspace to perform the encryption of the session key; for the
+ * foreseeable future, this will be the case with public key packets.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+/* Associate an authentication token(s) with the file */
+int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
+{
+	int rc = 0;
+	struct ecryptfs_crypt_stat *crypt_stat =
+	    &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+	    &ecryptfs_superblock_to_private(
+		    ecryptfs_dentry->d_sb)->mount_crypt_stat;
+	int cipher_name_len;
+
+	ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
+	/* See if there are mount crypt options */
+	if (mount_crypt_stat->global_auth_tok) {
+		ecryptfs_printk(KERN_DEBUG, "Initializing context for new "
+				"file using mount_crypt_stat\n");
+		ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
+		ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
+		memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++],
+		       mount_crypt_stat->global_auth_tok_sig,
+		       ECRYPTFS_SIG_SIZE_HEX);
+		cipher_name_len =
+		    strlen(mount_crypt_stat->global_default_cipher_name);
+		memcpy(crypt_stat->cipher,
+		       mount_crypt_stat->global_default_cipher_name,
+		       cipher_name_len);
+		crypt_stat->cipher[cipher_name_len] = '\0';
+		crypt_stat->key_size =
+			mount_crypt_stat->global_default_cipher_key_size;
+		ecryptfs_generate_new_key(crypt_stat);
+	} else
+		/* We should not encounter this scenario since we
+		 * should detect lack of global_auth_tok at mount time
+		 * TODO: Applies to 0.1 release only; remove in future
+		 * release */
+		BUG();
+	rc = ecryptfs_init_crypt_ctx(crypt_stat);
+	if (rc)
+		ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
+				"context for cipher [%s]: rc = [%d]\n",
+				crypt_stat->cipher, rc);
+	return rc;
+}
+
+/**
+ * contains_ecryptfs_marker - check for the ecryptfs marker
+ * @data: The data block in which to check
+ *
+ * Returns one if marker found; zero if not found
+ */
+int contains_ecryptfs_marker(char *data)
+{
+	u32 m_1, m_2;
+
+	memcpy(&m_1, data, 4);
+	m_1 = be32_to_cpu(m_1);
+	memcpy(&m_2, (data + 4), 4);
+	m_2 = be32_to_cpu(m_2);
+	if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
+		return 1;
+	ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
+			"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
+			MAGIC_ECRYPTFS_MARKER);
+	ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
+			"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
+	return 0;
+}
+
+struct ecryptfs_flag_map_elem {
+	u32 file_flag;
+	u32 local_flag;
+};
+
+/* Add support for additional flags by adding elements here. */
+static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
+	{0x00000001, ECRYPTFS_ENABLE_HMAC},
+	{0x00000002, ECRYPTFS_ENCRYPTED}
+};
+
+/**
+ * ecryptfs_process_flags
+ * @crypt_stat
+ * @page_virt: Source data to be parsed
+ * @bytes_read: Updated with the number of bytes read
+ *
+ * Returns zero on success; non-zero if the flag set is invalid
+ */
+static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
+				  char *page_virt, int *bytes_read)
+{
+	int rc = 0;
+	int i;
+	u32 flags;
+
+	memcpy(&flags, page_virt, 4);
+	flags = be32_to_cpu(flags);
+	for (i = 0; i < ((sizeof(ecryptfs_flag_map)
+			  / sizeof(struct ecryptfs_flag_map_elem))); i++)
+		if (flags & ecryptfs_flag_map[i].file_flag) {
+			ECRYPTFS_SET_FLAG(crypt_stat->flags,
+					  ecryptfs_flag_map[i].local_flag);
+		} else
+			ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
+					    ecryptfs_flag_map[i].local_flag);
+	/* Version is in top 8 bits of the 32-bit flag vector */
+	crypt_stat->file_version = ((flags >> 24) & 0xFF);
+	(*bytes_read) = 4;
+	return rc;
+}
+
+/**
+ * write_ecryptfs_marker
+ * @page_virt: The pointer to in a page to begin writing the marker
+ * @written: Number of bytes written
+ *
+ * Marker = 0x3c81b7f5
+ */
+static void write_ecryptfs_marker(char *page_virt, size_t *written)
+{
+	u32 m_1, m_2;
+
+	get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
+	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
+	m_1 = cpu_to_be32(m_1);
+	memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
+	m_2 = cpu_to_be32(m_2);
+	memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
+	       (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
+	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
+}
+
+static void
+write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
+		     size_t *written)
+{
+	u32 flags = 0;
+	int i;
+
+	for (i = 0; i < ((sizeof(ecryptfs_flag_map)
+			  / sizeof(struct ecryptfs_flag_map_elem))); i++)
+		if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+					ecryptfs_flag_map[i].local_flag))
+			flags |= ecryptfs_flag_map[i].file_flag;
+	/* Version is in top 8 bits of the 32-bit flag vector */
+	flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
+	flags = cpu_to_be32(flags);
+	memcpy(page_virt, &flags, 4);
+	(*written) = 4;
+}
+
+struct ecryptfs_cipher_code_str_map_elem {
+	char cipher_str[16];
+	u16 cipher_code;
+};
+
+/* Add support for additional ciphers by adding elements here. The
+ * cipher_code is whatever OpenPGP applicatoins use to identify the
+ * ciphers. List in order of probability. */
+static struct ecryptfs_cipher_code_str_map_elem
+ecryptfs_cipher_code_str_map[] = {
+	{"aes",RFC2440_CIPHER_AES_128 },
+	{"blowfish", RFC2440_CIPHER_BLOWFISH},
+	{"des3_ede", RFC2440_CIPHER_DES3_EDE},
+	{"cast5", RFC2440_CIPHER_CAST_5},
+	{"twofish", RFC2440_CIPHER_TWOFISH},
+	{"cast6", RFC2440_CIPHER_CAST_6},
+	{"aes", RFC2440_CIPHER_AES_192},
+	{"aes", RFC2440_CIPHER_AES_256}
+};
+
+/**
+ * ecryptfs_code_for_cipher_string
+ * @str: The string representing the cipher name
+ *
+ * Returns zero on no match, or the cipher code on match
+ */
+u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int i;
+	u16 code = 0;
+	struct ecryptfs_cipher_code_str_map_elem *map =
+		ecryptfs_cipher_code_str_map;
+
+	if (strcmp(crypt_stat->cipher, "aes") == 0) {
+		switch (crypt_stat->key_size) {
+		case 16:
+			code = RFC2440_CIPHER_AES_128;
+			break;
+		case 24:
+			code = RFC2440_CIPHER_AES_192;
+			break;
+		case 32:
+			code = RFC2440_CIPHER_AES_256;
+		}
+	} else {
+		for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
+			if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
+				code = map[i].cipher_code;
+				break;
+			}
+	}
+	return code;
+}
+
+/**
+ * ecryptfs_cipher_code_to_string
+ * @str: Destination to write out the cipher name
+ * @cipher_code: The code to convert to cipher name string
+ *
+ * Returns zero on success
+ */
+int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
+{
+	int rc = 0;
+	int i;
+
+	str[0] = '\0';
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
+		if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
+			strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
+	if (str[0] == '\0') {
+		ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
+				"[%d]\n", cipher_code);
+		rc = -EINVAL;
+	}
+	return rc;
+}
+
+/**
+ * ecryptfs_read_header_region
+ * @data
+ * @dentry
+ * @nd
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_read_header_region(char *data, struct dentry *dentry,
+				struct vfsmount *mnt)
+{
+	struct file *file;
+	mm_segment_t oldfs;
+	int rc;
+
+	mnt = mntget(mnt);
+	file = dentry_open(dentry, mnt, O_RDONLY);
+	if (IS_ERR(file)) {
+		ecryptfs_printk(KERN_DEBUG, "Error opening file to "
+				"read header region\n");
+		mntput(mnt);
+		rc = PTR_ERR(file);
+		goto out;
+	}
+	file->f_pos = 0;
+	oldfs = get_fs();
+	set_fs(get_ds());
+	/* For releases 0.1 and 0.2, all of the header information
+	 * fits in the first data extent-sized region. */
+	rc = file->f_op->read(file, (char __user *)data,
+			      ECRYPTFS_DEFAULT_EXTENT_SIZE, &file->f_pos);
+	set_fs(oldfs);
+	fput(file);
+	rc = 0;
+out:
+	return rc;
+}
+
+static void
+write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat,
+		      size_t *written)
+{
+	u32 header_extent_size;
+	u16 num_header_extents_at_front;
+
+	header_extent_size = (u32)crypt_stat->header_extent_size;
+	num_header_extents_at_front =
+		(u16)crypt_stat->num_header_extents_at_front;
+	header_extent_size = cpu_to_be32(header_extent_size);
+	memcpy(virt, &header_extent_size, 4);
+	virt += 4;
+	num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
+	memcpy(virt, &num_header_extents_at_front, 2);
+	(*written) = 6;
+}
+
+struct kmem_cache *ecryptfs_header_cache_0;
+struct kmem_cache *ecryptfs_header_cache_1;
+struct kmem_cache *ecryptfs_header_cache_2;
+
+/**
+ * ecryptfs_write_headers_virt
+ * @page_virt
+ * @crypt_stat
+ * @ecryptfs_dentry
+ *
+ * Format version: 1
+ *
+ *   Header Extent:
+ *     Octets 0-7:        Unencrypted file size (big-endian)
+ *     Octets 8-15:       eCryptfs special marker
+ *     Octets 16-19:      Flags
+ *      Octet 16:         File format version number (between 0 and 255)
+ *      Octets 17-18:     Reserved
+ *      Octet 19:         Bit 1 (lsb): Reserved
+ *                        Bit 2: Encrypted?
+ *                        Bits 3-8: Reserved
+ *     Octets 20-23:      Header extent size (big-endian)
+ *     Octets 24-25:      Number of header extents at front of file
+ *                        (big-endian)
+ *     Octet  26:         Begin RFC 2440 authentication token packet set
+ *   Data Extent 0:
+ *     Lower data (CBC encrypted)
+ *   Data Extent 1:
+ *     Lower data (CBC encrypted)
+ *   ...
+ *
+ * Returns zero on success
+ */
+int ecryptfs_write_headers_virt(char *page_virt,
+				struct ecryptfs_crypt_stat *crypt_stat,
+				struct dentry *ecryptfs_dentry)
+{
+	int rc;
+	size_t written;
+	size_t offset;
+
+	offset = ECRYPTFS_FILE_SIZE_BYTES;
+	write_ecryptfs_marker((page_virt + offset), &written);
+	offset += written;
+	write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
+	offset += written;
+	write_header_metadata((page_virt + offset), crypt_stat, &written);
+	offset += written;
+	rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
+					      ecryptfs_dentry, &written,
+					      PAGE_CACHE_SIZE - offset);
+	if (rc)
+		ecryptfs_printk(KERN_WARNING, "Error generating key packet "
+				"set; rc = [%d]\n", rc);
+	return rc;
+}
+
+/**
+ * ecryptfs_write_headers
+ * @lower_file: The lower file struct, which was returned from dentry_open
+ *
+ * Write the file headers out.  This will likely involve a userspace
+ * callout, in which the session key is encrypted with one or more
+ * public keys and/or the passphrase necessary to do the encryption is
+ * retrieved via a prompt.  Exactly what happens at this point should
+ * be policy-dependent.
+ *
+ * Returns zero on success; non-zero on error
+ */
+int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
+			   struct file *lower_file)
+{
+	mm_segment_t oldfs;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	char *page_virt;
+	int current_header_page;
+	int header_pages;
+	int rc = 0;
+
+	crypt_stat = &ecryptfs_inode_to_private(
+		ecryptfs_dentry->d_inode)->crypt_stat;
+	if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+				       ECRYPTFS_ENCRYPTED))) {
+		if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+					 ECRYPTFS_KEY_VALID)) {
+			ecryptfs_printk(KERN_DEBUG, "Key is "
+					"invalid; bailing out\n");
+			rc = -EINVAL;
+			goto out;
+		}
+	} else {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_WARNING,
+				"Called with crypt_stat->encrypted == 0\n");
+		goto out;
+	}
+	/* Released in this function */
+	page_virt = kmem_cache_alloc(ecryptfs_header_cache_0, SLAB_USER);
+	if (!page_virt) {
+		ecryptfs_printk(KERN_ERR, "Out of memory\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	memset(page_virt, 0, PAGE_CACHE_SIZE);
+	rc = ecryptfs_write_headers_virt(page_virt, crypt_stat,
+					 ecryptfs_dentry);
+	if (unlikely(rc)) {
+		ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
+		memset(page_virt, 0, PAGE_CACHE_SIZE);
+		goto out_free;
+	}
+	ecryptfs_printk(KERN_DEBUG,
+			"Writing key packet set to underlying file\n");
+	lower_file->f_pos = 0;
+	oldfs = get_fs();
+	set_fs(get_ds());
+	ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->"
+			"write() w/ header page; lower_file->f_pos = "
+			"[0x%.16x]\n", lower_file->f_pos);
+	lower_file->f_op->write(lower_file, (char __user *)page_virt,
+				PAGE_CACHE_SIZE, &lower_file->f_pos);
+	header_pages = ((crypt_stat->header_extent_size
+			 * crypt_stat->num_header_extents_at_front)
+			/ PAGE_CACHE_SIZE);
+	memset(page_virt, 0, PAGE_CACHE_SIZE);
+	current_header_page = 1;
+	while (current_header_page < header_pages) {
+		ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->"
+				"write() w/ zero'd page; lower_file->f_pos = "
+				"[0x%.16x]\n", lower_file->f_pos);
+		lower_file->f_op->write(lower_file, (char __user *)page_virt,
+					PAGE_CACHE_SIZE, &lower_file->f_pos);
+		current_header_page++;
+	}
+	set_fs(oldfs);
+	ecryptfs_printk(KERN_DEBUG,
+			"Done writing key packet set to underlying file.\n");
+out_free:
+	kmem_cache_free(ecryptfs_header_cache_0, page_virt);
+out:
+	return rc;
+}
+
+static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
+				 char *virt, int *bytes_read)
+{
+	int rc = 0;
+	u32 header_extent_size;
+	u16 num_header_extents_at_front;
+
+	memcpy(&header_extent_size, virt, 4);
+	header_extent_size = be32_to_cpu(header_extent_size);
+	virt += 4;
+	memcpy(&num_header_extents_at_front, virt, 2);
+	num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
+	crypt_stat->header_extent_size = (int)header_extent_size;
+	crypt_stat->num_header_extents_at_front =
+		(int)num_header_extents_at_front;
+	(*bytes_read) = 6;
+	if ((crypt_stat->header_extent_size
+	     * crypt_stat->num_header_extents_at_front)
+	    < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
+				"[%d]\n", crypt_stat->header_extent_size);
+	}
+	return rc;
+}
+
+/**
+ * set_default_header_data
+ *
+ * For version 0 file format; this function is only for backwards
+ * compatibility for files created with the prior versions of
+ * eCryptfs.
+ */
+static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
+{
+	crypt_stat->header_extent_size = 4096;
+	crypt_stat->num_header_extents_at_front = 1;
+}
+
+/**
+ * ecryptfs_read_headers_virt
+ *
+ * Read/parse the header data. The header format is detailed in the
+ * comment block for the ecryptfs_write_headers_virt() function.
+ *
+ * Returns zero on success
+ */
+static int ecryptfs_read_headers_virt(char *page_virt,
+				      struct ecryptfs_crypt_stat *crypt_stat,
+				      struct dentry *ecryptfs_dentry)
+{
+	int rc = 0;
+	int offset;
+	int bytes_read;
+
+	ecryptfs_set_default_sizes(crypt_stat);
+	crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
+		ecryptfs_dentry->d_sb)->mount_crypt_stat;
+	offset = ECRYPTFS_FILE_SIZE_BYTES;
+	rc = contains_ecryptfs_marker(page_virt + offset);
+	if (rc == 0) {
+		rc = -EINVAL;
+		goto out;
+	}
+	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
+	rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
+				    &bytes_read);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
+		goto out;
+	}
+	if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
+		ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
+				"file version [%d] is supported by this "
+				"version of eCryptfs\n",
+				crypt_stat->file_version,
+				ECRYPTFS_SUPPORTED_FILE_VERSION);
+		rc = -EINVAL;
+		goto out;
+	}
+	offset += bytes_read;
+	if (crypt_stat->file_version >= 1) {
+		rc = parse_header_metadata(crypt_stat, (page_virt + offset),
+					   &bytes_read);
+		if (rc) {
+			ecryptfs_printk(KERN_WARNING, "Error reading header "
+					"metadata; rc = [%d]\n", rc);
+		}
+		offset += bytes_read;
+	} else
+		set_default_header_data(crypt_stat);
+	rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
+				       ecryptfs_dentry);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_read_headers
+ *
+ * Returns zero if valid headers found and parsed; non-zero otherwise
+ */
+int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
+			  struct file *lower_file)
+{
+	int rc = 0;
+	char *page_virt = NULL;
+	mm_segment_t oldfs;
+	ssize_t bytes_read;
+	struct ecryptfs_crypt_stat *crypt_stat =
+	    &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
+
+	/* Read the first page from the underlying file */
+	page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_USER);
+	if (!page_virt) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
+		goto out;
+	}
+	lower_file->f_pos = 0;
+	oldfs = get_fs();
+	set_fs(get_ds());
+	bytes_read = lower_file->f_op->read(lower_file,
+					    (char __user *)page_virt,
+					    ECRYPTFS_DEFAULT_EXTENT_SIZE,
+					    &lower_file->f_pos);
+	set_fs(oldfs);
+	if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
+		rc = -EINVAL;
+		goto out;
+	}
+	rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
+					ecryptfs_dentry);
+	if (rc) {
+		ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not "
+				"found\n");
+		rc = -EINVAL;
+	}
+out:
+	if (page_virt) {
+		memset(page_virt, 0, PAGE_CACHE_SIZE);
+		kmem_cache_free(ecryptfs_header_cache_1, page_virt);
+	}
+	return rc;
+}
+
+/**
+ * ecryptfs_encode_filename - converts a plaintext file name to cipher text
+ * @crypt_stat: The crypt_stat struct associated with the file anem to encode
+ * @name: The plaintext name
+ * @length: The length of the plaintext
+ * @encoded_name: The encypted name
+ *
+ * Encrypts and encodes a filename into something that constitutes a
+ * valid filename for a filesystem, with printable characters.
+ *
+ * We assume that we have a properly initialized crypto context,
+ * pointed to by crypt_stat->tfm.
+ *
+ * TODO: Implement filename decoding and decryption here, in place of
+ * memcpy. We are keeping the framework around for now to (1)
+ * facilitate testing of the components needed to implement filename
+ * encryption and (2) to provide a code base from which other
+ * developers in the community can easily implement this feature.
+ *
+ * Returns the length of encoded filename; negative if error
+ */
+int
+ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
+			 const char *name, int length, char **encoded_name)
+{
+	int error = 0;
+
+	(*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
+	if (!(*encoded_name)) {
+		error = -ENOMEM;
+		goto out;
+	}
+	/* TODO: Filename encryption is a scheduled feature for a
+	 * future version of eCryptfs. This function is here only for
+	 * the purpose of providing a framework for other developers
+	 * to easily implement filename encryption. Hint: Replace this
+	 * memcpy() with a call to encrypt and encode the
+	 * filename, the set the length accordingly. */
+	memcpy((void *)(*encoded_name), (void *)name, length);
+	(*encoded_name)[length] = '\0';
+	error = length + 1;
+out:
+	return error;
+}
+
+/**
+ * ecryptfs_decode_filename - converts the cipher text name to plaintext
+ * @crypt_stat: The crypt_stat struct associated with the file
+ * @name: The filename in cipher text
+ * @length: The length of the cipher text name
+ * @decrypted_name: The plaintext name
+ *
+ * Decodes and decrypts the filename.
+ *
+ * We assume that we have a properly initialized crypto context,
+ * pointed to by crypt_stat->tfm.
+ *
+ * TODO: Implement filename decoding and decryption here, in place of
+ * memcpy. We are keeping the framework around for now to (1)
+ * facilitate testing of the components needed to implement filename
+ * encryption and (2) to provide a code base from which other
+ * developers in the community can easily implement this feature.
+ *
+ * Returns the length of decoded filename; negative if error
+ */
+int
+ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
+			 const char *name, int length, char **decrypted_name)
+{
+	int error = 0;
+
+	(*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
+	if (!(*decrypted_name)) {
+		error = -ENOMEM;
+		goto out;
+	}
+	/* TODO: Filename encryption is a scheduled feature for a
+	 * future version of eCryptfs. This function is here only for
+	 * the purpose of providing a framework for other developers
+	 * to easily implement filename encryption. Hint: Replace this
+	 * memcpy() with a call to decode and decrypt the
+	 * filename, the set the length accordingly. */
+	memcpy((void *)(*decrypted_name), (void *)name, length);
+	(*decrypted_name)[length + 1] = '\0';	/* Only for convenience
+						 * in printing out the
+						 * string in debug
+						 * messages */
+	error = length;
+out:
+	return error;
+}
+
+/**
+ * ecryptfs_process_cipher - Perform cipher initialization.
+ * @tfm: Crypto context set by this function
+ * @key_tfm: Crypto context for key material, set by this function
+ * @cipher_name: Name of the cipher.
+ * @key_size: Size of the key in bytes.
+ *
+ * Returns zero on success. Any crypto_tfm structs allocated here
+ * should be released by other functions, such as on a superblock put
+ * event, regardless of whether this function succeeds for fails.
+ */
+int
+ecryptfs_process_cipher(struct crypto_tfm **tfm, struct crypto_tfm **key_tfm,
+			char *cipher_name, size_t key_size)
+{
+	char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
+	int rc;
+
+	*tfm = *key_tfm = NULL;
+	if (key_size > ECRYPTFS_MAX_KEY_BYTES) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
+		       "allowable is [%d]\n", key_size, ECRYPTFS_MAX_KEY_BYTES);
+		goto out;
+	}
+	*tfm = crypto_alloc_tfm(cipher_name, (ECRYPTFS_DEFAULT_CHAINING_MODE
+					      | CRYPTO_TFM_REQ_WEAK_KEY));
+	if (!(*tfm)) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Unable to allocate crypto cipher with name "
+		       "[%s]\n", cipher_name);
+		goto out;
+	}
+	*key_tfm = crypto_alloc_tfm(cipher_name, CRYPTO_TFM_REQ_WEAK_KEY);
+	if (!(*key_tfm)) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Unable to allocate crypto cipher with name "
+		       "[%s]\n", cipher_name);
+		goto out;
+	}
+	if (key_size < crypto_tfm_alg_min_keysize(*tfm)) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Request key size is [%Zd]; minimum key size "
+		       "supported by cipher [%s] is [%d]\n", key_size,
+		       cipher_name, crypto_tfm_alg_min_keysize(*tfm));
+		goto out;
+	}
+	if (key_size < crypto_tfm_alg_min_keysize(*key_tfm)) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Request key size is [%Zd]; minimum key size "
+		       "supported by cipher [%s] is [%d]\n", key_size,
+		       cipher_name, crypto_tfm_alg_min_keysize(*key_tfm));
+		goto out;
+	}
+	if (key_size > crypto_tfm_alg_max_keysize(*tfm)) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Request key size is [%Zd]; maximum key size "
+		       "supported by cipher [%s] is [%d]\n", key_size,
+		       cipher_name, crypto_tfm_alg_min_keysize(*tfm));
+		goto out;
+	}
+	if (key_size > crypto_tfm_alg_max_keysize(*key_tfm)) {
+		rc = -EINVAL;
+		printk(KERN_ERR "Request key size is [%Zd]; maximum key size "
+		       "supported by cipher [%s] is [%d]\n", key_size,
+		       cipher_name, crypto_tfm_alg_min_keysize(*key_tfm));
+		goto out;
+	}
+	get_random_bytes(dummy_key, key_size);
+	rc = crypto_cipher_setkey(*tfm, dummy_key, key_size);
+	if (rc) {
+		printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
+		       "cipher [%s]; rc = [%d]\n", key_size, cipher_name, rc);
+		rc = -EINVAL;
+		goto out;
+	}
+	rc = crypto_cipher_setkey(*key_tfm, dummy_key, key_size);
+	if (rc) {
+		printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
+		       "cipher [%s]; rc = [%d]\n", key_size, cipher_name, rc);
+		rc = -EINVAL;
+		goto out;
+	}
+out:
+	return rc;
+}

fs/ecryptfs/debug.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * Functions only useful for debugging.
+ *
+ * Copyright (C) 2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include "ecryptfs_kernel.h"
+
+/**
+ * ecryptfs_dump_auth_tok - debug function to print auth toks
+ *
+ * This function will print the contents of an ecryptfs authentication
+ * token.
+ */
+void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok)
+{
+	char salt[ECRYPTFS_SALT_SIZE * 2 + 1];
+	char sig[ECRYPTFS_SIG_SIZE_HEX + 1];
+
+	ecryptfs_printk(KERN_DEBUG, "Auth tok at mem loc [%p]:\n",
+			auth_tok);
+	if (ECRYPTFS_CHECK_FLAG(auth_tok->flags, ECRYPTFS_PRIVATE_KEY)) {
+		ecryptfs_printk(KERN_DEBUG, " * private key type\n");
+		ecryptfs_printk(KERN_DEBUG, " * (NO PRIVATE KEY SUPPORT "
+				"IN ECRYPTFS VERSION 0.1)\n");
+	} else {
+		ecryptfs_printk(KERN_DEBUG, " * passphrase type\n");
+		ecryptfs_to_hex(salt, auth_tok->token.password.salt,
+				ECRYPTFS_SALT_SIZE);
+		salt[ECRYPTFS_SALT_SIZE * 2] = '\0';
+		ecryptfs_printk(KERN_DEBUG, " * salt = [%s]\n", salt);
+		if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags,
+					ECRYPTFS_PERSISTENT_PASSWORD)) {
+			ecryptfs_printk(KERN_DEBUG, " * persistent\n");
+		}
+		memcpy(sig, auth_tok->token.password.signature,
+		       ECRYPTFS_SIG_SIZE_HEX);
+		sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
+		ecryptfs_printk(KERN_DEBUG, " * signature = [%s]\n", sig);
+	}
+	ecryptfs_printk(KERN_DEBUG, " * session_key.flags = [0x%x]\n",
+			auth_tok->session_key.flags);
+	if (auth_tok->session_key.flags
+	    & ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT)
+		ecryptfs_printk(KERN_DEBUG,
+				" * Userspace decrypt request set\n");
+	if (auth_tok->session_key.flags
+	    & ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT)
+		ecryptfs_printk(KERN_DEBUG,
+				" * Userspace encrypt request set\n");
+	if (auth_tok->session_key.flags & ECRYPTFS_CONTAINS_DECRYPTED_KEY) {
+		ecryptfs_printk(KERN_DEBUG, " * Contains decrypted key\n");
+		ecryptfs_printk(KERN_DEBUG,
+				" * session_key.decrypted_key_size = [0x%x]\n",
+				auth_tok->session_key.decrypted_key_size);
+		ecryptfs_printk(KERN_DEBUG, " * Decrypted session key "
+				"dump:\n");
+		if (ecryptfs_verbosity > 0)
+			ecryptfs_dump_hex(auth_tok->session_key.decrypted_key,
+					  ECRYPTFS_DEFAULT_KEY_BYTES);
+	}
+	if (auth_tok->session_key.flags & ECRYPTFS_CONTAINS_ENCRYPTED_KEY) {
+		ecryptfs_printk(KERN_DEBUG, " * Contains encrypted key\n");
+		ecryptfs_printk(KERN_DEBUG,
+				" * session_key.encrypted_key_size = [0x%x]\n",
+				auth_tok->session_key.encrypted_key_size);
+		ecryptfs_printk(KERN_DEBUG, " * Encrypted session key "
+				"dump:\n");
+		if (ecryptfs_verbosity > 0)
+			ecryptfs_dump_hex(auth_tok->session_key.encrypted_key,
+					  auth_tok->session_key.
+					  encrypted_key_size);
+	}
+}
+
+/**
+ * ecryptfs_dump_hex - debug hex printer
+ * @data: string of bytes to be printed
+ * @bytes: number of bytes to print
+ *
+ * Dump hexadecimal representation of char array
+ */
+void ecryptfs_dump_hex(char *data, int bytes)
+{
+	int i = 0;
+	int add_newline = 1;
+
+	if (ecryptfs_verbosity < 1)
+		return;
+	if (bytes != 0) {
+		printk(KERN_DEBUG "0x%.2x.", (unsigned char)data[i]);
+		i++;
+	}
+	while (i < bytes) {
+		printk("0x%.2x.", (unsigned char)data[i]);
+		i++;
+		if (i % 16 == 0) {
+			printk("\n");
+			add_newline = 0;
+		} else
+			add_newline = 1;
+	}
+	if (add_newline)
+		printk("\n");
+}
+

fs/ecryptfs/dentry.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/dcache.h>
+#include <linux/namei.h>
+#include "ecryptfs_kernel.h"
+
+/**
+ * ecryptfs_d_revalidate - revalidate an ecryptfs dentry
+ * @dentry: The ecryptfs dentry
+ * @nd: The associated nameidata
+ *
+ * Called when the VFS needs to revalidate a dentry. This
+ * is called whenever a name lookup finds a dentry in the
+ * dcache. Most filesystems leave this as NULL, because all their
+ * dentries in the dcache are valid.
+ *
+ * Returns 1 if valid, 0 otherwise.
+ *
+ */
+static int ecryptfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
+	struct dentry *dentry_save;
+	struct vfsmount *vfsmount_save;
+	int rc = 1;
+
+	if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
+		goto out;
+	dentry_save = nd->dentry;
+	vfsmount_save = nd->mnt;
+	nd->dentry = lower_dentry;
+	nd->mnt = lower_mnt;
+	rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
+	nd->dentry = dentry_save;
+	nd->mnt = vfsmount_save;
+out:
+	return rc;
+}
+
+struct kmem_cache *ecryptfs_dentry_info_cache;
+
+/**
+ * ecryptfs_d_release
+ * @dentry: The ecryptfs dentry
+ *
+ * Called when a dentry is really deallocated.
+ */
+static void ecryptfs_d_release(struct dentry *dentry)
+{
+	struct dentry *lower_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (ecryptfs_dentry_to_private(dentry))
+		kmem_cache_free(ecryptfs_dentry_info_cache,
+				ecryptfs_dentry_to_private(dentry));
+	if (lower_dentry)
+		dput(lower_dentry);
+	return;
+}
+
+struct dentry_operations ecryptfs_dops = {
+	.d_revalidate = ecryptfs_d_revalidate,
+	.d_release = ecryptfs_d_release,
+};

fs/ecryptfs/ecryptfs_kernel.h

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * Kernel declarations.
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#ifndef ECRYPTFS_KERNEL_H
+#define ECRYPTFS_KERNEL_H
+
+#include <keys/user-type.h>
+#include <linux/fs.h>
+#include <linux/scatterlist.h>
+
+/* Version verification for shared data structures w/ userspace */
+#define ECRYPTFS_VERSION_MAJOR 0x00
+#define ECRYPTFS_VERSION_MINOR 0x04
+#define ECRYPTFS_SUPPORTED_FILE_VERSION 0x01
+/* These flags indicate which features are supported by the kernel
+ * module; userspace tools such as the mount helper read
+ * ECRYPTFS_VERSIONING_MASK from a sysfs handle in order to determine
+ * how to behave. */
+#define ECRYPTFS_VERSIONING_PASSPHRASE 0x00000001
+#define ECRYPTFS_VERSIONING_PUBKEY 0x00000002
+#define ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH 0x00000004
+#define ECRYPTFS_VERSIONING_POLICY 0x00000008
+#define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \
+                                  | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH)
+
+#define ECRYPTFS_MAX_PASSWORD_LENGTH 64
+#define ECRYPTFS_MAX_PASSPHRASE_BYTES ECRYPTFS_MAX_PASSWORD_LENGTH
+#define ECRYPTFS_SALT_SIZE 8
+#define ECRYPTFS_SALT_SIZE_HEX (ECRYPTFS_SALT_SIZE*2)
+/* The original signature size is only for what is stored on disk; all
+ * in-memory representations are expanded hex, so it better adapted to
+ * be passed around or referenced on the command line */
+#define ECRYPTFS_SIG_SIZE 8
+#define ECRYPTFS_SIG_SIZE_HEX (ECRYPTFS_SIG_SIZE*2)
+#define ECRYPTFS_PASSWORD_SIG_SIZE ECRYPTFS_SIG_SIZE_HEX
+#define ECRYPTFS_MAX_KEY_BYTES 64
+#define ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES 512
+#define ECRYPTFS_DEFAULT_IV_BYTES 16
+#define ECRYPTFS_FILE_VERSION 0x01
+#define ECRYPTFS_DEFAULT_HEADER_EXTENT_SIZE 8192
+#define ECRYPTFS_DEFAULT_EXTENT_SIZE 4096
+#define ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE 8192
+
+#define RFC2440_CIPHER_DES3_EDE 0x02
+#define RFC2440_CIPHER_CAST_5 0x03
+#define RFC2440_CIPHER_BLOWFISH 0x04
+#define RFC2440_CIPHER_AES_128 0x07
+#define RFC2440_CIPHER_AES_192 0x08
+#define RFC2440_CIPHER_AES_256 0x09
+#define RFC2440_CIPHER_TWOFISH 0x0a
+#define RFC2440_CIPHER_CAST_6 0x0b
+
+#define ECRYPTFS_SET_FLAG(flag_bit_vector, flag) (flag_bit_vector |= (flag))
+#define ECRYPTFS_CLEAR_FLAG(flag_bit_vector, flag) (flag_bit_vector &= ~(flag))
+#define ECRYPTFS_CHECK_FLAG(flag_bit_vector, flag) (flag_bit_vector & (flag))
+
+/**
+ * For convenience, we may need to pass around the encrypted session
+ * key between kernel and userspace because the authentication token
+ * may not be extractable.  For example, the TPM may not release the
+ * private key, instead requiring the encrypted data and returning the
+ * decrypted data.
+ */
+struct ecryptfs_session_key {
+#define ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT 0x00000001
+#define ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT 0x00000002
+#define ECRYPTFS_CONTAINS_DECRYPTED_KEY 0x00000004
+#define ECRYPTFS_CONTAINS_ENCRYPTED_KEY 0x00000008
+	u32 flags;
+	u32 encrypted_key_size;
+	u32 decrypted_key_size;
+	u8 encrypted_key[ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES];
+	u8 decrypted_key[ECRYPTFS_MAX_KEY_BYTES];
+};
+
+struct ecryptfs_password {
+	u32 password_bytes;
+	s32 hash_algo;
+	u32 hash_iterations;
+	u32 session_key_encryption_key_bytes;
+#define ECRYPTFS_PERSISTENT_PASSWORD 0x01
+#define ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET 0x02
+	u32 flags;
+	/* Iterated-hash concatenation of salt and passphrase */
+	u8 session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
+	u8 signature[ECRYPTFS_PASSWORD_SIG_SIZE + 1];
+	/* Always in expanded hex */
+	u8 salt[ECRYPTFS_SALT_SIZE];
+};
+
+enum ecryptfs_token_types {ECRYPTFS_PASSWORD, ECRYPTFS_PRIVATE_KEY};
+
+/* May be a password or a private key */
+struct ecryptfs_auth_tok {
+	u16 version; /* 8-bit major and 8-bit minor */
+	u16 token_type;
+	u32 flags;
+	struct ecryptfs_session_key session_key;
+	u8 reserved[32];
+	union {
+		struct ecryptfs_password password;
+		/* Private key is in future eCryptfs releases */
+	} token;
+} __attribute__ ((packed));
+
+void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok);
+extern void ecryptfs_to_hex(char *dst, char *src, size_t src_size);
+extern void ecryptfs_from_hex(char *dst, char *src, int dst_size);
+
+struct ecryptfs_key_record {
+	unsigned char type;
+	size_t enc_key_size;
+	unsigned char sig[ECRYPTFS_SIG_SIZE];
+	unsigned char enc_key[ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES];
+};
+
+struct ecryptfs_auth_tok_list {
+	struct ecryptfs_auth_tok *auth_tok;
+	struct list_head list;
+};
+
+struct ecryptfs_crypt_stat;
+struct ecryptfs_mount_crypt_stat;
+
+struct ecryptfs_page_crypt_context {
+	struct page *page;
+#define ECRYPTFS_PREPARE_COMMIT_MODE 0
+#define ECRYPTFS_WRITEPAGE_MODE      1
+	unsigned int mode;
+	union {
+		struct file *lower_file;
+		struct writeback_control *wbc;
+	} param;
+};
+
+static inline struct ecryptfs_auth_tok *
+ecryptfs_get_key_payload_data(struct key *key)
+{
+	return (struct ecryptfs_auth_tok *)
+		(((struct user_key_payload*)key->payload.data)->data);
+}
+
+#define ECRYPTFS_SUPER_MAGIC 0xf15f
+#define ECRYPTFS_MAX_KEYSET_SIZE 1024
+#define ECRYPTFS_MAX_CIPHER_NAME_SIZE 32
+#define ECRYPTFS_MAX_NUM_ENC_KEYS 64
+#define ECRYPTFS_MAX_NUM_KEYSIGS 2 /* TODO: Make this a linked list */
+#define ECRYPTFS_MAX_IV_BYTES 16	/* 128 bits */
+#define ECRYPTFS_SALT_BYTES 2
+#define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5
+#define MAGIC_ECRYPTFS_MARKER_SIZE_BYTES 8	/* 4*2 */
+#define ECRYPTFS_FILE_SIZE_BYTES 8
+#define ECRYPTFS_DEFAULT_CIPHER "aes"
+#define ECRYPTFS_DEFAULT_KEY_BYTES 16
+#define ECRYPTFS_DEFAULT_CHAINING_MODE CRYPTO_TFM_MODE_CBC
+#define ECRYPTFS_TAG_3_PACKET_TYPE 0x8C
+#define ECRYPTFS_TAG_11_PACKET_TYPE 0xED
+#define MD5_DIGEST_SIZE 16
+
+/**
+ * This is the primary struct associated with each encrypted file.
+ *
+ * TODO: cache align/pack?
+ */
+struct ecryptfs_crypt_stat {
+#define ECRYPTFS_STRUCT_INITIALIZED 0x00000001
+#define ECRYPTFS_POLICY_APPLIED     0x00000002
+#define ECRYPTFS_NEW_FILE           0x00000004
+#define ECRYPTFS_ENCRYPTED          0x00000008
+#define ECRYPTFS_SECURITY_WARNING   0x00000010
+#define ECRYPTFS_ENABLE_HMAC        0x00000020
+#define ECRYPTFS_ENCRYPT_IV_PAGES   0x00000040
+#define ECRYPTFS_KEY_VALID          0x00000080
+	u32 flags;
+	unsigned int file_version;
+	size_t iv_bytes;
+	size_t num_keysigs;
+	size_t header_extent_size;
+	size_t num_header_extents_at_front;
+	size_t extent_size; /* Data extent size; default is 4096 */
+	size_t key_size;
+	size_t extent_shift;
+	unsigned int extent_mask;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
+	struct crypto_tfm *tfm;
+	struct crypto_tfm *md5_tfm; /* Crypto context for generating
+				     * the initialization vectors */
+	unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
+	unsigned char key[ECRYPTFS_MAX_KEY_BYTES];
+	unsigned char root_iv[ECRYPTFS_MAX_IV_BYTES];
+	unsigned char keysigs[ECRYPTFS_MAX_NUM_KEYSIGS][ECRYPTFS_SIG_SIZE_HEX];
+	struct mutex cs_tfm_mutex;
+	struct mutex cs_md5_tfm_mutex;
+	struct mutex cs_mutex;
+};
+
+/* inode private data. */
+struct ecryptfs_inode_info {
+	struct inode vfs_inode;
+	struct inode *wii_inode;
+	struct ecryptfs_crypt_stat crypt_stat;
+};
+
+/* dentry private data. Each dentry must keep track of a lower
+ * vfsmount too. */
+struct ecryptfs_dentry_info {
+	struct dentry *wdi_dentry;
+	struct vfsmount *lower_mnt;
+	struct ecryptfs_crypt_stat *crypt_stat;
+};
+
+/**
+ * This struct is to enable a mount-wide passphrase/salt combo. This
+ * is more or less a stopgap to provide similar functionality to other
+ * crypto filesystems like EncFS or CFS until full policy support is
+ * implemented in eCryptfs.
+ */
+struct ecryptfs_mount_crypt_stat {
+	/* Pointers to memory we do not own, do not free these */
+#define ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED 0x00000001
+	u32 flags;
+	struct ecryptfs_auth_tok *global_auth_tok;
+	struct key *global_auth_tok_key;
+	size_t global_default_cipher_key_size;
+	struct crypto_tfm *global_key_tfm;
+	struct mutex global_key_tfm_mutex;
+	unsigned char global_default_cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE
+						 + 1];
+	unsigned char global_auth_tok_sig[ECRYPTFS_SIG_SIZE_HEX + 1];
+};
+
+/* superblock private data. */
+struct ecryptfs_sb_info {
+	struct super_block *wsi_sb;
+	struct ecryptfs_mount_crypt_stat mount_crypt_stat;
+};
+
+/* file private data. */
+struct ecryptfs_file_info {
+	struct file *wfi_file;
+	struct ecryptfs_crypt_stat *crypt_stat;
+};
+
+/* auth_tok <=> encrypted_session_key mappings */
+struct ecryptfs_auth_tok_list_item {
+	unsigned char encrypted_session_key[ECRYPTFS_MAX_KEY_BYTES];
+	struct list_head list;
+	struct ecryptfs_auth_tok auth_tok;
+};
+
+static inline struct ecryptfs_file_info *
+ecryptfs_file_to_private(struct file *file)
+{
+	return (struct ecryptfs_file_info *)file->private_data;
+}
+
+static inline void
+ecryptfs_set_file_private(struct file *file,
+			  struct ecryptfs_file_info *file_info)
+{
+	file->private_data = file_info;
+}
+
+static inline struct file *ecryptfs_file_to_lower(struct file *file)
+{
+	return ((struct ecryptfs_file_info *)file->private_data)->wfi_file;
+}
+
+static inline void
+ecryptfs_set_file_lower(struct file *file, struct file *lower_file)
+{
+	((struct ecryptfs_file_info *)file->private_data)->wfi_file =
+		lower_file;
+}
+
+static inline struct ecryptfs_inode_info *
+ecryptfs_inode_to_private(struct inode *inode)
+{
+	return container_of(inode, struct ecryptfs_inode_info, vfs_inode);
+}
+
+static inline struct inode *ecryptfs_inode_to_lower(struct inode *inode)
+{
+	return ecryptfs_inode_to_private(inode)->wii_inode;
+}
+
+static inline void
+ecryptfs_set_inode_lower(struct inode *inode, struct inode *lower_inode)
+{
+	ecryptfs_inode_to_private(inode)->wii_inode = lower_inode;
+}
+
+static inline struct ecryptfs_sb_info *
+ecryptfs_superblock_to_private(struct super_block *sb)
+{
+	return (struct ecryptfs_sb_info *)sb->s_fs_info;
+}
+
+static inline void
+ecryptfs_set_superblock_private(struct super_block *sb,
+				struct ecryptfs_sb_info *sb_info)
+{
+	sb->s_fs_info = sb_info;
+}
+
+static inline struct super_block *
+ecryptfs_superblock_to_lower(struct super_block *sb)
+{
+	return ((struct ecryptfs_sb_info *)sb->s_fs_info)->wsi_sb;
+}
+
+static inline void
+ecryptfs_set_superblock_lower(struct super_block *sb,
+			      struct super_block *lower_sb)
+{
+	((struct ecryptfs_sb_info *)sb->s_fs_info)->wsi_sb = lower_sb;
+}
+
+static inline struct ecryptfs_dentry_info *
+ecryptfs_dentry_to_private(struct dentry *dentry)
+{
+	return (struct ecryptfs_dentry_info *)dentry->d_fsdata;
+}
+
+static inline void
+ecryptfs_set_dentry_private(struct dentry *dentry,
+			    struct ecryptfs_dentry_info *dentry_info)
+{
+	dentry->d_fsdata = dentry_info;
+}
+
+static inline struct dentry *
+ecryptfs_dentry_to_lower(struct dentry *dentry)
+{
+	return ((struct ecryptfs_dentry_info *)dentry->d_fsdata)->wdi_dentry;
+}
+
+static inline void
+ecryptfs_set_dentry_lower(struct dentry *dentry, struct dentry *lower_dentry)
+{
+	((struct ecryptfs_dentry_info *)dentry->d_fsdata)->wdi_dentry =
+		lower_dentry;
+}
+
+static inline struct vfsmount *
+ecryptfs_dentry_to_lower_mnt(struct dentry *dentry)
+{
+	return ((struct ecryptfs_dentry_info *)dentry->d_fsdata)->lower_mnt;
+}
+
+static inline void
+ecryptfs_set_dentry_lower_mnt(struct dentry *dentry, struct vfsmount *lower_mnt)
+{
+	((struct ecryptfs_dentry_info *)dentry->d_fsdata)->lower_mnt =
+		lower_mnt;
+}
+
+#define ecryptfs_printk(type, fmt, arg...) \
+        __ecryptfs_printk(type "%s: " fmt, __FUNCTION__, ## arg);
+void __ecryptfs_printk(const char *fmt, ...);
+
+extern const struct file_operations ecryptfs_main_fops;
+extern const struct file_operations ecryptfs_dir_fops;
+extern struct inode_operations ecryptfs_main_iops;
+extern struct inode_operations ecryptfs_dir_iops;
+extern struct inode_operations ecryptfs_symlink_iops;
+extern struct super_operations ecryptfs_sops;
+extern struct dentry_operations ecryptfs_dops;
+extern struct address_space_operations ecryptfs_aops;
+extern int ecryptfs_verbosity;
+
+extern struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
+extern struct kmem_cache *ecryptfs_file_info_cache;
+extern struct kmem_cache *ecryptfs_dentry_info_cache;
+extern struct kmem_cache *ecryptfs_inode_info_cache;
+extern struct kmem_cache *ecryptfs_sb_info_cache;
+extern struct kmem_cache *ecryptfs_header_cache_0;
+extern struct kmem_cache *ecryptfs_header_cache_1;
+extern struct kmem_cache *ecryptfs_header_cache_2;
+extern struct kmem_cache *ecryptfs_lower_page_cache;
+
+int ecryptfs_interpose(struct dentry *hidden_dentry,
+		       struct dentry *this_dentry, struct super_block *sb,
+		       int flag);
+int ecryptfs_fill_zeros(struct file *file, loff_t new_length);
+int ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
+			     const char *name, int length,
+			     char **decrypted_name);
+int ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
+			     const char *name, int length,
+			     char **encoded_name);
+struct dentry *ecryptfs_lower_dentry(struct dentry *this_dentry);
+void ecryptfs_copy_attr_atime(struct inode *dest, const struct inode *src);
+void ecryptfs_copy_attr_all(struct inode *dest, const struct inode *src);
+void ecryptfs_copy_inode_size(struct inode *dst, const struct inode *src);
+void ecryptfs_dump_hex(char *data, int bytes);
+int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
+			int sg_size);
+int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat);
+void ecryptfs_rotate_iv(unsigned char *iv);
+void ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat);
+void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat);
+void ecryptfs_destruct_mount_crypt_stat(
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat);
+int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat);
+int ecryptfs_write_inode_size_to_header(struct file *lower_file,
+					struct inode *lower_inode,
+					struct inode *inode);
+int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
+			    struct file *lower_file,
+			    unsigned long lower_page_index, int byte_offset,
+			    int region_bytes);
+int
+ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
+			   struct file *lower_file, int byte_offset,
+			   int region_size);
+int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
+				struct file *lower_file);
+int ecryptfs_do_readpage(struct file *file, struct page *page,
+			 pgoff_t lower_page_index);
+int ecryptfs_grab_and_map_lower_page(struct page **lower_page,
+				     char **lower_virt,
+				     struct inode *lower_inode,
+				     unsigned long lower_page_index);
+int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
+					      struct inode *lower_inode,
+					      struct writeback_control *wbc);
+int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx);
+int ecryptfs_decrypt_page(struct file *file, struct page *page);
+int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
+			   struct file *lower_file);
+int ecryptfs_write_headers_virt(char *page_virt,
+				struct ecryptfs_crypt_stat *crypt_stat,
+				struct dentry *ecryptfs_dentry);
+int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
+			  struct file *lower_file);
+int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry);
+int contains_ecryptfs_marker(char *data);
+int ecryptfs_read_header_region(char *data, struct dentry *dentry,
+				struct vfsmount *mnt);
+u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat);
+int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code);
+void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
+int ecryptfs_generate_key_packet_set(char *dest_base,
+				     struct ecryptfs_crypt_stat *crypt_stat,
+				     struct dentry *ecryptfs_dentry,
+				     size_t *len, size_t max);
+int process_request_key_err(long err_code);
+int
+ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
+			  unsigned char *src, struct dentry *ecryptfs_dentry);
+int ecryptfs_truncate(struct dentry *dentry, loff_t new_length);
+int
+ecryptfs_process_cipher(struct crypto_tfm **tfm, struct crypto_tfm **key_tfm,
+			char *cipher_name, size_t key_size);
+int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode);
+int ecryptfs_inode_set(struct inode *inode, void *lower_inode);
+void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode);
+
+#endif /* #ifndef ECRYPTFS_KERNEL_H */

fs/ecryptfs/file.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2004 Erez Zadok
+ * Copyright (C) 2001-2004 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *   		Michael C. Thompson <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/security.h>
+#include <linux/smp_lock.h>
+#include <linux/compat.h>
+#include "ecryptfs_kernel.h"
+
+/**
+ * ecryptfs_llseek
+ * @file: File we are seeking in
+ * @offset: The offset to seek to
+ * @origin: 2 - offset from i_size; 1 - offset from f_pos
+ *
+ * Returns the position we have seeked to, or negative on error
+ */
+static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin)
+{
+	loff_t rv;
+	loff_t new_end_pos;
+	int rc;
+	int expanding_file = 0;
+	struct inode *inode = file->f_mapping->host;
+
+	/* If our offset is past the end of our file, we're going to
+	 * need to grow it so we have a valid length of 0's */
+	new_end_pos = offset;
+	switch (origin) {
+	case 2:
+		new_end_pos += i_size_read(inode);
+		expanding_file = 1;
+		break;
+	case 1:
+		new_end_pos += file->f_pos;
+		if (new_end_pos > i_size_read(inode)) {
+			ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
+					"> i_size_read(inode)(=[0x%.16x])\n",
+					new_end_pos, i_size_read(inode));
+			expanding_file = 1;
+		}
+		break;
+	default:
+		if (new_end_pos > i_size_read(inode)) {
+			ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
+					"> i_size_read(inode)(=[0x%.16x])\n",
+					new_end_pos, i_size_read(inode));
+			expanding_file = 1;
+		}
+	}
+	ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos);
+	if (expanding_file) {
+		rc = ecryptfs_truncate(file->f_dentry, new_end_pos);
+		if (rc) {
+			rv = rc;
+			ecryptfs_printk(KERN_ERR, "Error on attempt to "
+					"truncate to (higher) offset [0x%.16x];"
+					" rc = [%d]\n", new_end_pos, rc);
+			goto out;
+		}
+	}
+	rv = generic_file_llseek(file, offset, origin);
+out:
+	return rv;
+}
+
+/**
+ * ecryptfs_read_update_atime
+ *
+ * generic_file_read updates the atime of upper layer inode.  But, it
+ * doesn't give us a chance to update the atime of the lower layer
+ * inode.  This function is a wrapper to generic_file_read.  It
+ * updates the atime of the lower level inode if generic_file_read
+ * returns without any errors. This is to be used only for file reads.
+ * The function to be used for directory reads is ecryptfs_read.
+ */
+static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
+				const struct iovec *iov,
+				unsigned long nr_segs, loff_t pos)
+{
+	int rc;
+	struct dentry *lower_dentry;
+	struct vfsmount *lower_vfsmount;
+	struct file *file = iocb->ki_filp;
+
+	rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
+	/*
+	 * Even though this is a async interface, we need to wait
+	 * for IO to finish to update atime
+	 */
+	if (-EIOCBQUEUED == rc)
+		rc = wait_on_sync_kiocb(iocb);
+	if (rc >= 0) {
+		lower_dentry = ecryptfs_dentry_to_lower(file->f_dentry);
+		lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_dentry);
+		touch_atime(lower_vfsmount, lower_dentry);
+	}
+	return rc;
+}
+
+struct ecryptfs_getdents_callback {
+	void *dirent;
+	struct dentry *dentry;
+	filldir_t filldir;
+	int err;
+	int filldir_called;
+	int entries_written;
+};
+
+/* Inspired by generic filldir in fs/readir.c */
+static int
+ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
+		 u64 ino, unsigned int d_type)
+{
+	struct ecryptfs_crypt_stat *crypt_stat;
+	struct ecryptfs_getdents_callback *buf =
+	    (struct ecryptfs_getdents_callback *)dirent;
+	int rc;
+	int decoded_length;
+	char *decoded_name;
+
+	crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
+	buf->filldir_called++;
+	decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
+						  &decoded_name);
+	if (decoded_length < 0) {
+		rc = decoded_length;
+		goto out;
+	}
+	rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
+			  ino, d_type);
+	kfree(decoded_name);
+	if (rc >= 0)
+		buf->entries_written++;
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_readdir
+ * @file: The ecryptfs file struct
+ * @dirent: Directory entry
+ * @filldir: The filldir callback function
+ */
+static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+	int rc;
+	struct file *lower_file;
+	struct inode *inode;
+	struct ecryptfs_getdents_callback buf;
+
+	lower_file = ecryptfs_file_to_lower(file);
+	lower_file->f_pos = file->f_pos;
+	inode = file->f_dentry->d_inode;
+	memset(&buf, 0, sizeof(buf));
+	buf.dirent = dirent;
+	buf.dentry = file->f_dentry;
+	buf.filldir = filldir;
+retry:
+	buf.filldir_called = 0;
+	buf.entries_written = 0;
+	buf.err = 0;
+	rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
+	if (buf.err)
+		rc = buf.err;
+	if (buf.filldir_called && !buf.entries_written)
+		goto retry;
+	file->f_pos = lower_file->f_pos;
+	if (rc >= 0)
+		ecryptfs_copy_attr_atime(inode, lower_file->f_dentry->d_inode);
+	return rc;
+}
+
+struct kmem_cache *ecryptfs_file_info_cache;
+
+/**
+ * ecryptfs_open
+ * @inode: inode speciying file to open
+ * @file: Structure to return filled in
+ *
+ * Opens the file specified by inode.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_open(struct inode *inode, struct file *file)
+{
+	int rc = 0;
+	struct ecryptfs_crypt_stat *crypt_stat = NULL;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
+	struct dentry *ecryptfs_dentry = file->f_dentry;
+	/* Private value of ecryptfs_dentry allocated in
+	 * ecryptfs_lookup() */
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+	struct inode *lower_inode = NULL;
+	struct file *lower_file = NULL;
+	struct vfsmount *lower_mnt;
+	struct ecryptfs_file_info *file_info;
+	int lower_flags;
+
+	/* Released in ecryptfs_release or end of function if failure */
+	file_info = kmem_cache_alloc(ecryptfs_file_info_cache, SLAB_KERNEL);
+	ecryptfs_set_file_private(file, file_info);
+	if (!file_info) {
+		ecryptfs_printk(KERN_ERR,
+				"Error attempting to allocate memory\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	memset(file_info, 0, sizeof(*file_info));
+	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
+	mount_crypt_stat = &ecryptfs_superblock_to_private(
+		ecryptfs_dentry->d_sb)->mount_crypt_stat;
+	mutex_lock(&crypt_stat->cs_mutex);
+	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED)) {
+		ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
+		/* Policy code enabled in future release */
+		ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED);
+		ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
+	}
+	mutex_unlock(&crypt_stat->cs_mutex);
+	/* This mntget & dget is undone via fput when the file is released */
+	dget(lower_dentry);
+	lower_flags = file->f_flags;
+	if ((lower_flags & O_ACCMODE) == O_WRONLY)
+		lower_flags = (lower_flags & O_ACCMODE) | O_RDWR;
+	if (file->f_flags & O_APPEND)
+		lower_flags &= ~O_APPEND;
+	lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
+	mntget(lower_mnt);
+	/* Corresponding fput() in ecryptfs_release() */
+	lower_file = dentry_open(lower_dentry, lower_mnt, lower_flags);
+	if (IS_ERR(lower_file)) {
+		rc = PTR_ERR(lower_file);
+		ecryptfs_printk(KERN_ERR, "Error opening lower file\n");
+		goto out_puts;
+	}
+	ecryptfs_set_file_lower(file, lower_file);
+	/* Isn't this check the same as the one in lookup? */
+	lower_inode = lower_dentry->d_inode;
+	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
+		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
+		ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
+		rc = 0;
+		goto out;
+	}
+	mutex_lock(&crypt_stat->cs_mutex);
+	if (i_size_read(lower_inode) < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
+		if (!(mount_crypt_stat->flags
+		      & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
+			rc = -EIO;
+			printk(KERN_WARNING "Attempt to read file that is "
+			       "not in a valid eCryptfs format, and plaintext "
+			       "passthrough mode is not enabled; returning "
+			       "-EIO\n");
+			mutex_unlock(&crypt_stat->cs_mutex);
+			goto out_puts;
+		}
+		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
+		rc = 0;
+		mutex_unlock(&crypt_stat->cs_mutex);
+		goto out;
+	} else if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+					ECRYPTFS_POLICY_APPLIED)
+		   || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+					   ECRYPTFS_KEY_VALID)) {
+		rc = ecryptfs_read_headers(ecryptfs_dentry, lower_file);
+		if (rc) {
+			ecryptfs_printk(KERN_DEBUG,
+					"Valid headers not found\n");
+			if (!(mount_crypt_stat->flags
+			      & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
+				rc = -EIO;
+				printk(KERN_WARNING "Attempt to read file that "
+				       "is not in a valid eCryptfs format, "
+				       "and plaintext passthrough mode is not "
+				       "enabled; returning -EIO\n");
+				mutex_unlock(&crypt_stat->cs_mutex);
+				goto out_puts;
+			}
+			ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
+					    ECRYPTFS_ENCRYPTED);
+			rc = 0;
+			mutex_unlock(&crypt_stat->cs_mutex);
+			goto out;
+		}
+	}
+	mutex_unlock(&crypt_stat->cs_mutex);
+	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
+			"size: [0x%.16x]\n", inode, inode->i_ino,
+			i_size_read(inode));
+	ecryptfs_set_file_lower(file, lower_file);
+	goto out;
+out_puts:
+	mntput(lower_mnt);
+	dput(lower_dentry);
+	kmem_cache_free(ecryptfs_file_info_cache,
+			ecryptfs_file_to_private(file));
+out:
+	return rc;
+}
+
+static int ecryptfs_flush(struct file *file, fl_owner_t td)
+{
+	int rc = 0;
+	struct file *lower_file = NULL;
+
+	lower_file = ecryptfs_file_to_lower(file);
+	if (lower_file->f_op && lower_file->f_op->flush)
+		rc = lower_file->f_op->flush(lower_file, td);
+	return rc;
+}
+
+static int ecryptfs_release(struct inode *inode, struct file *file)
+{
+	struct file *lower_file = ecryptfs_file_to_lower(file);
+	struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file);
+	struct inode *lower_inode = ecryptfs_inode_to_lower(inode);
+
+	fput(lower_file);
+	inode->i_blocks = lower_inode->i_blocks;
+	kmem_cache_free(ecryptfs_file_info_cache, file_info);
+	return 0;
+}
+
+static int
+ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+	struct file *lower_file = ecryptfs_file_to_lower(file);
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	struct inode *lower_inode = lower_dentry->d_inode;
+	int rc = -EINVAL;
+
+	if (lower_inode->i_fop->fsync) {
+		mutex_lock(&lower_inode->i_mutex);
+		rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
+					       datasync);
+		mutex_unlock(&lower_inode->i_mutex);
+	}
+	return rc;
+}
+
+static int ecryptfs_fasync(int fd, struct file *file, int flag)
+{
+	int rc = 0;
+	struct file *lower_file = NULL;
+
+	lower_file = ecryptfs_file_to_lower(file);
+	if (lower_file->f_op && lower_file->f_op->fasync)
+		rc = lower_file->f_op->fasync(fd, lower_file, flag);
+	return rc;
+}
+
+static ssize_t ecryptfs_sendfile(struct file *file, loff_t * ppos,
+				 size_t count, read_actor_t actor, void *target)
+{
+	struct file *lower_file = NULL;
+	int rc = -EINVAL;
+
+	lower_file = ecryptfs_file_to_lower(file);
+	if (lower_file->f_op && lower_file->f_op->sendfile)
+		rc = lower_file->f_op->sendfile(lower_file, ppos, count,
+						actor, target);
+
+	return rc;
+}
+
+static int ecryptfs_ioctl(struct inode *inode, struct file *file,
+			  unsigned int cmd, unsigned long arg);
+
+const struct file_operations ecryptfs_dir_fops = {
+	.readdir = ecryptfs_readdir,
+	.ioctl = ecryptfs_ioctl,
+	.mmap = generic_file_mmap,
+	.open = ecryptfs_open,
+	.flush = ecryptfs_flush,
+	.release = ecryptfs_release,
+	.fsync = ecryptfs_fsync,
+	.fasync = ecryptfs_fasync,
+	.sendfile = ecryptfs_sendfile,
+};
+
+const struct file_operations ecryptfs_main_fops = {
+	.llseek = ecryptfs_llseek,
+	.read = do_sync_read,
+	.aio_read = ecryptfs_read_update_atime,
+	.write = do_sync_write,
+	.aio_write = generic_file_aio_write,
+	.readdir = ecryptfs_readdir,
+	.ioctl = ecryptfs_ioctl,
+	.mmap = generic_file_mmap,
+	.open = ecryptfs_open,
+	.flush = ecryptfs_flush,
+	.release = ecryptfs_release,
+	.fsync = ecryptfs_fsync,
+	.fasync = ecryptfs_fasync,
+	.sendfile = ecryptfs_sendfile,
+};
+
+static int
+ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+	       unsigned long arg)
+{
+	int rc = 0;
+	struct file *lower_file = NULL;
+
+	if (ecryptfs_file_to_private(file))
+		lower_file = ecryptfs_file_to_lower(file);
+	if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
+		rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
+					     lower_file, cmd, arg);
+	else
+		rc = -ENOTTY;
+	return rc;
+}

fs/ecryptfs/inode.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2004 Erez Zadok
+ * Copyright (C) 2001-2004 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *              Michael C. Thompsion <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/file.h>
+#include <linux/vmalloc.h>
+#include <linux/pagemap.h>
+#include <linux/dcache.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/crypto.h>
+#include "ecryptfs_kernel.h"
+
+static struct dentry *lock_parent(struct dentry *dentry)
+{
+	struct dentry *dir;
+
+	dir = dget(dentry->d_parent);
+	mutex_lock(&(dir->d_inode->i_mutex));
+	return dir;
+}
+
+static void unlock_parent(struct dentry *dentry)
+{
+	mutex_unlock(&(dentry->d_parent->d_inode->i_mutex));
+	dput(dentry->d_parent);
+}
+
+static void unlock_dir(struct dentry *dir)
+{
+	mutex_unlock(&dir->d_inode->i_mutex);
+	dput(dir);
+}
+
+void ecryptfs_copy_inode_size(struct inode *dst, const struct inode *src)
+{
+	i_size_write(dst, i_size_read((struct inode *)src));
+	dst->i_blocks = src->i_blocks;
+}
+
+void ecryptfs_copy_attr_atime(struct inode *dest, const struct inode *src)
+{
+	dest->i_atime = src->i_atime;
+}
+
+static void ecryptfs_copy_attr_times(struct inode *dest,
+				     const struct inode *src)
+{
+	dest->i_atime = src->i_atime;
+	dest->i_mtime = src->i_mtime;
+	dest->i_ctime = src->i_ctime;
+}
+
+static void ecryptfs_copy_attr_timesizes(struct inode *dest,
+					 const struct inode *src)
+{
+	dest->i_atime = src->i_atime;
+	dest->i_mtime = src->i_mtime;
+	dest->i_ctime = src->i_ctime;
+	ecryptfs_copy_inode_size(dest, src);
+}
+
+void ecryptfs_copy_attr_all(struct inode *dest, const struct inode *src)
+{
+	dest->i_mode = src->i_mode;
+	dest->i_nlink = src->i_nlink;
+	dest->i_uid = src->i_uid;
+	dest->i_gid = src->i_gid;
+	dest->i_rdev = src->i_rdev;
+	dest->i_atime = src->i_atime;
+	dest->i_mtime = src->i_mtime;
+	dest->i_ctime = src->i_ctime;
+	dest->i_blkbits = src->i_blkbits;
+	dest->i_flags = src->i_flags;
+}
+
+/**
+ * ecryptfs_create_underlying_file
+ * @lower_dir_inode: inode of the parent in the lower fs of the new file
+ * @lower_dentry: New file's dentry in the lower fs
+ * @ecryptfs_dentry: New file's dentry in ecryptfs
+ * @mode: The mode of the new file
+ * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
+ *
+ * Creates the file in the lower file system.
+ *
+ * Returns zero on success; non-zero on error condition
+ */
+static int
+ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
+				struct dentry *dentry, int mode,
+				struct nameidata *nd)
+{
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
+	struct dentry *dentry_save;
+	struct vfsmount *vfsmount_save;
+	int rc;
+
+	dentry_save = nd->dentry;
+	vfsmount_save = nd->mnt;
+	nd->dentry = lower_dentry;
+	nd->mnt = lower_mnt;
+	rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
+	nd->dentry = dentry_save;
+	nd->mnt = vfsmount_save;
+	return rc;
+}
+
+/**
+ * ecryptfs_do_create
+ * @directory_inode: inode of the new file's dentry's parent in ecryptfs
+ * @ecryptfs_dentry: New file's dentry in ecryptfs
+ * @mode: The mode of the new file
+ * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
+ *
+ * Creates the underlying file and the eCryptfs inode which will link to
+ * it. It will also update the eCryptfs directory inode to mimic the
+ * stat of the lower directory inode.
+ *
+ * Returns zero on success; non-zero on error condition
+ */
+static int
+ecryptfs_do_create(struct inode *directory_inode,
+		   struct dentry *ecryptfs_dentry, int mode,
+		   struct nameidata *nd)
+{
+	int rc;
+	struct dentry *lower_dentry;
+	struct dentry *lower_dir_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+	lower_dir_dentry = lock_parent(lower_dentry);
+	if (unlikely(IS_ERR(lower_dir_dentry))) {
+		ecryptfs_printk(KERN_ERR, "Error locking directory of "
+				"dentry\n");
+		rc = PTR_ERR(lower_dir_dentry);
+		goto out;
+	}
+	rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
+					     ecryptfs_dentry, mode, nd);
+	if (unlikely(rc)) {
+		ecryptfs_printk(KERN_ERR,
+				"Failure to create underlying file\n");
+		goto out_lock;
+	}
+	rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
+				directory_inode->i_sb, 0);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
+		goto out_lock;
+	}
+	ecryptfs_copy_attr_timesizes(directory_inode,
+				     lower_dir_dentry->d_inode);
+out_lock:
+	unlock_dir(lower_dir_dentry);
+out:
+	return rc;
+}
+
+/**
+ * grow_file
+ * @ecryptfs_dentry: the ecryptfs dentry
+ * @lower_file: The lower file
+ * @inode: The ecryptfs inode
+ * @lower_inode: The lower inode
+ *
+ * This is the code which will grow the file to its correct size.
+ */
+static int grow_file(struct dentry *ecryptfs_dentry, struct file *lower_file,
+		     struct inode *inode, struct inode *lower_inode)
+{
+	int rc = 0;
+	struct file fake_file;
+	struct ecryptfs_file_info tmp_file_info;
+
+	memset(&fake_file, 0, sizeof(fake_file));
+	fake_file.f_dentry = ecryptfs_dentry;
+	memset(&tmp_file_info, 0, sizeof(tmp_file_info));
+	ecryptfs_set_file_private(&fake_file, &tmp_file_info);
+	ecryptfs_set_file_lower(&fake_file, lower_file);
+	rc = ecryptfs_fill_zeros(&fake_file, 1);
+	if (rc) {
+		ECRYPTFS_SET_FLAG(
+			ecryptfs_inode_to_private(inode)->crypt_stat.flags,
+			ECRYPTFS_SECURITY_WARNING);
+		ecryptfs_printk(KERN_WARNING, "Error attempting to fill zeros "
+				"in file; rc = [%d]\n", rc);
+		goto out;
+	}
+	i_size_write(inode, 0);
+	ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
+	ECRYPTFS_SET_FLAG(ecryptfs_inode_to_private(inode)->crypt_stat.flags,
+			  ECRYPTFS_NEW_FILE);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_initialize_file
+ *
+ * Cause the file to be changed from a basic empty file to an ecryptfs
+ * file with a header and first data page.
+ *
+ * Returns zero on success
+ */
+static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
+{
+	int rc = 0;
+	int lower_flags;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	struct dentry *lower_dentry;
+	struct dentry *tlower_dentry = NULL;
+	struct file *lower_file;
+	struct inode *inode, *lower_inode;
+	struct vfsmount *lower_mnt;
+
+	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+	ecryptfs_printk(KERN_DEBUG, "lower_dentry->d_name.name = [%s]\n",
+			lower_dentry->d_name.name);
+	inode = ecryptfs_dentry->d_inode;
+	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
+	tlower_dentry = dget(lower_dentry);
+	if (!tlower_dentry) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error dget'ing lower_dentry\n");
+		goto out;
+	}
+	lower_flags = ((O_CREAT | O_WRONLY | O_TRUNC) & O_ACCMODE) | O_RDWR;
+#if BITS_PER_LONG != 32
+	lower_flags |= O_LARGEFILE;
+#endif
+	lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
+	mntget(lower_mnt);
+	/* Corresponding fput() at end of this function */
+	lower_file = dentry_open(tlower_dentry, lower_mnt, lower_flags);
+	if (IS_ERR(lower_file)) {
+		rc = PTR_ERR(lower_file);
+		ecryptfs_printk(KERN_ERR,
+				"Error opening dentry; rc = [%i]\n", rc);
+		goto out;
+	}
+	/* fput(lower_file) should handle the puts if we do this */
+	lower_file->f_dentry = tlower_dentry;
+	lower_file->f_vfsmnt = lower_mnt;
+	lower_inode = tlower_dentry->d_inode;
+	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
+		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
+		ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
+		goto out_fput;
+	}
+	ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE);
+	ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
+	rc = ecryptfs_new_file_context(ecryptfs_dentry);
+	if (rc) {
+		ecryptfs_printk(KERN_DEBUG, "Error creating new file "
+				"context\n");
+		goto out_fput;
+	}
+	rc = ecryptfs_write_headers(ecryptfs_dentry, lower_file);
+	if (rc) {
+		ecryptfs_printk(KERN_DEBUG, "Error writing headers\n");
+		goto out_fput;
+	}
+	rc = grow_file(ecryptfs_dentry, lower_file, inode, lower_inode);
+out_fput:
+	fput(lower_file);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_create
+ * @dir: The inode of the directory in which to create the file.
+ * @dentry: The eCryptfs dentry
+ * @mode: The mode of the new file.
+ * @nd: nameidata
+ *
+ * Creates a new file.
+ *
+ * Returns zero on success; non-zero on error condition
+ */
+static int
+ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
+		int mode, struct nameidata *nd)
+{
+	int rc;
+
+	rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
+	if (unlikely(rc)) {
+		ecryptfs_printk(KERN_WARNING, "Failed to create file in"
+				"lower filesystem\n");
+		goto out;
+	}
+	/* At this point, a file exists on "disk"; we need to make sure
+	 * that this on disk file is prepared to be an ecryptfs file */
+	rc = ecryptfs_initialize_file(ecryptfs_dentry);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_lookup
+ * @dir: inode
+ * @dentry: The dentry
+ * @nd: nameidata, may be NULL
+ *
+ * Find a file on disk. If the file does not exist, then we'll add it to the
+ * dentry cache and continue on to read it from the disk.
+ */
+static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
+				      struct nameidata *nd)
+{
+	int rc = 0;
+	struct dentry *lower_dir_dentry;
+	struct dentry *lower_dentry;
+	struct vfsmount *lower_mnt;
+	struct dentry *tlower_dentry = NULL;
+	char *encoded_name;
+	unsigned int encoded_namelen;
+	struct ecryptfs_crypt_stat *crypt_stat = NULL;
+	char *page_virt = NULL;
+	struct inode *lower_inode;
+	u64 file_size;
+
+	lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
+	dentry->d_op = &ecryptfs_dops;
+	if ((dentry->d_name.len == 1 && !strcmp(dentry->d_name.name, "."))
+	    || (dentry->d_name.len == 2 && !strcmp(dentry->d_name.name, "..")))
+		goto out_drop;
+	encoded_namelen = ecryptfs_encode_filename(crypt_stat,
+						   dentry->d_name.name,
+						   dentry->d_name.len,
+						   &encoded_name);
+	if (encoded_namelen < 0) {
+		rc = encoded_namelen;
+		goto out_drop;
+	}
+	ecryptfs_printk(KERN_DEBUG, "encoded_name = [%s]; encoded_namelen "
+			"= [%d]\n", encoded_name, encoded_namelen);
+	lower_dentry = lookup_one_len(encoded_name, lower_dir_dentry,
+				      encoded_namelen - 1);
+	kfree(encoded_name);
+	lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
+	if (IS_ERR(lower_dentry)) {
+		ecryptfs_printk(KERN_ERR, "ERR from lower_dentry\n");
+		rc = PTR_ERR(lower_dentry);
+		goto out_drop;
+	}
+	ecryptfs_printk(KERN_DEBUG, "lower_dentry = [%p]; lower_dentry->"
+       		"d_name.name = [%s]\n", lower_dentry,
+		lower_dentry->d_name.name);
+	lower_inode = lower_dentry->d_inode;
+	ecryptfs_copy_attr_atime(dir, lower_dir_dentry->d_inode);
+	BUG_ON(!atomic_read(&lower_dentry->d_count));
+	ecryptfs_set_dentry_private(dentry,
+				    kmem_cache_alloc(ecryptfs_dentry_info_cache,
+						     SLAB_KERNEL));
+	if (!ecryptfs_dentry_to_private(dentry)) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Out of memory whilst attempting "
+				"to allocate ecryptfs_dentry_info struct\n");
+		goto out_dput;
+	}
+	ecryptfs_set_dentry_lower(dentry, lower_dentry);
+	ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
+	if (!lower_dentry->d_inode) {
+		/* We want to add because we couldn't find in lower */
+		d_add(dentry, NULL);
+		goto out;
+	}
+	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 1);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error interposing\n");
+		goto out_dput;
+	}
+	if (S_ISDIR(lower_inode->i_mode)) {
+		ecryptfs_printk(KERN_DEBUG, "Is a directory; returning\n");
+		goto out;
+	}
+	if (S_ISLNK(lower_inode->i_mode)) {
+		ecryptfs_printk(KERN_DEBUG, "Is a symlink; returning\n");
+		goto out;
+	}
+	if (!nd) {
+		ecryptfs_printk(KERN_DEBUG, "We have a NULL nd, just leave"
+				"as we *think* we are about to unlink\n");
+		goto out;
+	}
+	tlower_dentry = dget(lower_dentry);
+	if (!tlower_dentry || IS_ERR(tlower_dentry)) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Cannot dget lower_dentry\n");
+		goto out_dput;
+	}
+	/* Released in this function */
+	page_virt =
+	    (char *)kmem_cache_alloc(ecryptfs_header_cache_2,
+				     SLAB_USER);
+	if (!page_virt) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR,
+				"Cannot ecryptfs_kmalloc a page\n");
+		goto out_dput;
+	}
+	memset(page_virt, 0, PAGE_CACHE_SIZE);
+	rc = ecryptfs_read_header_region(page_virt, tlower_dentry, nd->mnt);
+	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
+	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED))
+		ecryptfs_set_default_sizes(crypt_stat);
+	if (rc) {
+		rc = 0;
+		ecryptfs_printk(KERN_WARNING, "Error reading header region;"
+				" assuming unencrypted\n");
+	} else {
+		if (!contains_ecryptfs_marker(page_virt
+					      + ECRYPTFS_FILE_SIZE_BYTES)) {
+			kmem_cache_free(ecryptfs_header_cache_2, page_virt);
+			goto out;
+		}
+		memcpy(&file_size, page_virt, sizeof(file_size));
+		file_size = be64_to_cpu(file_size);
+		i_size_write(dentry->d_inode, (loff_t)file_size);
+	}
+	kmem_cache_free(ecryptfs_header_cache_2, page_virt);
+	goto out;
+
+out_dput:
+	dput(lower_dentry);
+	if (tlower_dentry)
+		dput(tlower_dentry);
+out_drop:
+	d_drop(dentry);
+out:
+	return ERR_PTR(rc);
+}
+
+static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
+			 struct dentry *new_dentry)
+{
+	struct dentry *lower_old_dentry;
+	struct dentry *lower_new_dentry;
+	struct dentry *lower_dir_dentry;
+	u64 file_size_save;
+	int rc;
+
+	file_size_save = i_size_read(old_dentry->d_inode);
+	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
+	lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
+	dget(lower_old_dentry);
+	dget(lower_new_dentry);
+	lower_dir_dentry = lock_parent(lower_new_dentry);
+	rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
+		      lower_new_dentry);
+	if (rc || !lower_new_dentry->d_inode)
+		goto out_lock;
+	rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
+	if (rc)
+		goto out_lock;
+	ecryptfs_copy_attr_timesizes(dir, lower_new_dentry->d_inode);
+	old_dentry->d_inode->i_nlink =
+		ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
+	i_size_write(new_dentry->d_inode, file_size_save);
+out_lock:
+	unlock_dir(lower_dir_dentry);
+	dput(lower_new_dentry);
+	dput(lower_old_dentry);
+	if (!new_dentry->d_inode)
+		d_drop(new_dentry);
+	return rc;
+}
+
+static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	int rc = 0;
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
+
+	lock_parent(lower_dentry);
+	rc = vfs_unlink(lower_dir_inode, lower_dentry);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error in vfs_unlink\n");
+		goto out_unlock;
+	}
+	ecryptfs_copy_attr_times(dir, lower_dir_inode);
+	dentry->d_inode->i_nlink =
+		ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
+	dentry->d_inode->i_ctime = dir->i_ctime;
+out_unlock:
+	unlock_parent(lower_dentry);
+	return rc;
+}
+
+static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
+			    const char *symname)
+{
+	int rc;
+	struct dentry *lower_dentry;
+	struct dentry *lower_dir_dentry;
+	umode_t mode;
+	char *encoded_symname;
+	unsigned int encoded_symlen;
+	struct ecryptfs_crypt_stat *crypt_stat = NULL;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	dget(lower_dentry);
+	lower_dir_dentry = lock_parent(lower_dentry);
+	mode = S_IALLUGO;
+	encoded_symlen = ecryptfs_encode_filename(crypt_stat, symname,
+						  strlen(symname),
+						  &encoded_symname);
+	if (encoded_symlen < 0) {
+		rc = encoded_symlen;
+		goto out_lock;
+	}
+	rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
+			 encoded_symname, mode);
+	kfree(encoded_symname);
+	if (rc || !lower_dentry->d_inode)
+		goto out_lock;
+	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
+	if (rc)
+		goto out_lock;
+	ecryptfs_copy_attr_timesizes(dir, lower_dir_dentry->d_inode);
+out_lock:
+	unlock_dir(lower_dir_dentry);
+	dput(lower_dentry);
+	if (!dentry->d_inode)
+		d_drop(dentry);
+	return rc;
+}
+
+static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+	int rc;
+	struct dentry *lower_dentry;
+	struct dentry *lower_dir_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	lower_dir_dentry = lock_parent(lower_dentry);
+	rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
+	if (rc || !lower_dentry->d_inode)
+		goto out;
+	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
+	if (rc)
+		goto out;
+	ecryptfs_copy_attr_timesizes(dir, lower_dir_dentry->d_inode);
+	dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
+out:
+	unlock_dir(lower_dir_dentry);
+	if (!dentry->d_inode)
+		d_drop(dentry);
+	return rc;
+}
+
+static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	int rc = 0;
+	struct dentry *tdentry = NULL;
+	struct dentry *lower_dentry;
+	struct dentry *tlower_dentry = NULL;
+	struct dentry *lower_dir_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (!(tdentry = dget(dentry))) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_ERR, "Error dget'ing dentry [%p]\n",
+				dentry);
+		goto out;
+	}
+	lower_dir_dentry = lock_parent(lower_dentry);
+	if (!(tlower_dentry = dget(lower_dentry))) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_ERR, "Error dget'ing lower_dentry "
+				"[%p]\n", lower_dentry);
+		goto out;
+	}
+	rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
+	if (!rc) {
+		d_delete(tlower_dentry);
+		tlower_dentry = NULL;
+	}
+	ecryptfs_copy_attr_times(dir, lower_dir_dentry->d_inode);
+	dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
+	unlock_dir(lower_dir_dentry);
+	if (!rc)
+		d_drop(dentry);
+out:
+	if (tdentry)
+		dput(tdentry);
+	if (tlower_dentry)
+		dput(tlower_dentry);
+	return rc;
+}
+
+static int
+ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+{
+	int rc;
+	struct dentry *lower_dentry;
+	struct dentry *lower_dir_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	lower_dir_dentry = lock_parent(lower_dentry);
+	rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
+	if (rc || !lower_dentry->d_inode)
+		goto out;
+	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
+	if (rc)
+		goto out;
+	ecryptfs_copy_attr_timesizes(dir, lower_dir_dentry->d_inode);
+out:
+	unlock_dir(lower_dir_dentry);
+	if (!dentry->d_inode)
+		d_drop(dentry);
+	return rc;
+}
+
+static int
+ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+		struct inode *new_dir, struct dentry *new_dentry)
+{
+	int rc;
+	struct dentry *lower_old_dentry;
+	struct dentry *lower_new_dentry;
+	struct dentry *lower_old_dir_dentry;
+	struct dentry *lower_new_dir_dentry;
+
+	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
+	lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
+	dget(lower_old_dentry);
+	dget(lower_new_dentry);
+	lower_old_dir_dentry = dget_parent(lower_old_dentry);
+	lower_new_dir_dentry = dget_parent(lower_new_dentry);
+	lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
+			lower_new_dir_dentry->d_inode, lower_new_dentry);
+	if (rc)
+		goto out_lock;
+	ecryptfs_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode);
+	if (new_dir != old_dir)
+		ecryptfs_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode);
+out_lock:
+	unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	dput(lower_new_dentry);
+	dput(lower_old_dentry);
+	return rc;
+}
+
+static int
+ecryptfs_readlink(struct dentry *dentry, char __user * buf, int bufsiz)
+{
+	int rc;
+	struct dentry *lower_dentry;
+	char *decoded_name;
+	char *lower_buf;
+	mm_segment_t old_fs;
+	struct ecryptfs_crypt_stat *crypt_stat;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (!lower_dentry->d_inode->i_op ||
+	    !lower_dentry->d_inode->i_op->readlink) {
+		rc = -EINVAL;
+		goto out;
+	}
+	/* Released in this function */
+	lower_buf = kmalloc(bufsiz, GFP_KERNEL);
+	if (lower_buf == NULL) {
+		ecryptfs_printk(KERN_ERR, "Out of memory\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	old_fs = get_fs();
+	set_fs(get_ds());
+	ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
+			"lower_dentry->d_name.name = [%s]\n",
+			lower_dentry->d_name.name);
+	rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
+						   (char __user *)lower_buf,
+						   bufsiz);
+	set_fs(old_fs);
+	if (rc >= 0) {
+		crypt_stat = NULL;
+		rc = ecryptfs_decode_filename(crypt_stat, lower_buf, rc,
+					      &decoded_name);
+		if (rc == -ENOMEM)
+			goto out_free_lower_buf;
+		if (rc > 0) {
+			ecryptfs_printk(KERN_DEBUG, "Copying [%d] bytes "
+					"to userspace: [%*s]\n", rc,
+					decoded_name);
+			if (copy_to_user(buf, decoded_name, rc))
+				rc = -EFAULT;
+		}
+		kfree(decoded_name);
+		ecryptfs_copy_attr_atime(dentry->d_inode,
+					 lower_dentry->d_inode);
+	}
+out_free_lower_buf:
+	kfree(lower_buf);
+out:
+	return rc;
+}
+
+static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	char *buf;
+	int len = PAGE_SIZE, rc;
+	mm_segment_t old_fs;
+
+	/* Released in ecryptfs_put_link(); only release here on error */
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	old_fs = get_fs();
+	set_fs(get_ds());
+	ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
+			"dentry->d_name.name = [%s]\n", dentry->d_name.name);
+	rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
+	buf[rc] = '\0';
+	set_fs(old_fs);
+	if (rc < 0)
+		goto out_free;
+	rc = 0;
+	nd_set_link(nd, buf);
+	goto out;
+out_free:
+	kfree(buf);
+out:
+	return ERR_PTR(rc);
+}
+
+static void
+ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
+{
+	/* Free the char* */
+	kfree(nd_get_link(nd));
+}
+
+/**
+ * upper_size_to_lower_size
+ * @crypt_stat: Crypt_stat associated with file
+ * @upper_size: Size of the upper file
+ *
+ * Calculate the requried size of the lower file based on the
+ * specified size of the upper file. This calculation is based on the
+ * number of headers in the underlying file and the extent size.
+ *
+ * Returns Calculated size of the lower file.
+ */
+static loff_t
+upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
+			 loff_t upper_size)
+{
+	loff_t lower_size;
+
+	lower_size = ( crypt_stat->header_extent_size
+		       * crypt_stat->num_header_extents_at_front );
+	if (upper_size != 0) {
+		loff_t num_extents;
+
+		num_extents = upper_size >> crypt_stat->extent_shift;
+		if (upper_size & ~crypt_stat->extent_mask)
+			num_extents++;
+		lower_size += (num_extents * crypt_stat->extent_size);
+	}
+	return lower_size;
+}
+
+/**
+ * ecryptfs_truncate
+ * @dentry: The ecryptfs layer dentry
+ * @new_length: The length to expand the file to
+ *
+ * Function to handle truncations modifying the size of the file. Note
+ * that the file sizes are interpolated. When expanding, we are simply
+ * writing strings of 0's out. When truncating, we need to modify the
+ * underlying file size according to the page index interpolations.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
+{
+	int rc = 0;
+	struct inode *inode = dentry->d_inode;
+	struct dentry *lower_dentry;
+	struct vfsmount *lower_mnt;
+	struct file fake_ecryptfs_file, *lower_file = NULL;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	loff_t i_size = i_size_read(inode);
+	loff_t lower_size_before_truncate;
+	loff_t lower_size_after_truncate;
+
+	if (unlikely((new_length == i_size)))
+		goto out;
+	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
+	/* Set up a fake ecryptfs file, this is used to interface with
+	 * the file in the underlying filesystem so that the
+	 * truncation has an effect there as well. */
+	memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
+	fake_ecryptfs_file.f_dentry = dentry;
+	/* Released at out_free: label */
+	ecryptfs_set_file_private(&fake_ecryptfs_file,
+				  kmem_cache_alloc(ecryptfs_file_info_cache,
+						   SLAB_KERNEL));
+	if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	/* This dget & mntget is released through fput at out_fput: */
+	dget(lower_dentry);
+	lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
+	mntget(lower_mnt);
+	lower_file = dentry_open(lower_dentry, lower_mnt, O_RDWR);
+	if (unlikely(IS_ERR(lower_file))) {
+		rc = PTR_ERR(lower_file);
+		goto out_free;
+	}
+	ecryptfs_set_file_lower(&fake_ecryptfs_file, lower_file);
+	/* Switch on growing or shrinking file */
+	if (new_length > i_size) {
+		rc = ecryptfs_fill_zeros(&fake_ecryptfs_file, new_length);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR,
+					"Problem with fill_zeros\n");
+			goto out_fput;
+		}
+		i_size_write(inode, new_length);
+		rc = ecryptfs_write_inode_size_to_header(lower_file,
+							 lower_dentry->d_inode,
+							 inode);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR,
+					"Problem with ecryptfs_write"
+					"_inode_size\n");
+			goto out_fput;
+		}
+	} else { /* new_length < i_size_read(inode) */
+		vmtruncate(inode, new_length);
+		ecryptfs_write_inode_size_to_header(lower_file,
+						    lower_dentry->d_inode,
+						    inode);
+		/* We are reducing the size of the ecryptfs file, and need to
+		 * know if we need to reduce the size of the lower file. */
+		lower_size_before_truncate =
+		    upper_size_to_lower_size(crypt_stat, i_size);
+		lower_size_after_truncate =
+		    upper_size_to_lower_size(crypt_stat, new_length);
+		if (lower_size_after_truncate < lower_size_before_truncate)
+			vmtruncate(lower_dentry->d_inode,
+				   lower_size_after_truncate);
+	}
+	/* Update the access times */
+	lower_dentry->d_inode->i_mtime = lower_dentry->d_inode->i_ctime
+		= CURRENT_TIME;
+	mark_inode_dirty_sync(inode);
+out_fput:
+	fput(lower_file);
+out_free:
+	if (ecryptfs_file_to_private(&fake_ecryptfs_file))
+		kmem_cache_free(ecryptfs_file_info_cache,
+				ecryptfs_file_to_private(&fake_ecryptfs_file));
+out:
+	return rc;
+}
+
+static int
+ecryptfs_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+	int rc;
+
+        if (nd) {
+		struct vfsmount *vfsmnt_save = nd->mnt;
+		struct dentry *dentry_save = nd->dentry;
+
+		nd->mnt = ecryptfs_dentry_to_lower_mnt(nd->dentry);
+		nd->dentry = ecryptfs_dentry_to_lower(nd->dentry);
+		rc = permission(ecryptfs_inode_to_lower(inode), mask, nd);
+		nd->mnt = vfsmnt_save;
+		nd->dentry = dentry_save;
+        } else
+		rc = permission(ecryptfs_inode_to_lower(inode), mask, NULL);
+        return rc;
+}
+
+/**
+ * ecryptfs_setattr
+ * @dentry: dentry handle to the inode to modify
+ * @ia: Structure with flags of what to change and values
+ *
+ * Updates the metadata of an inode. If the update is to the size
+ * i.e. truncation, then ecryptfs_truncate will handle the size modification
+ * of both the ecryptfs inode and the lower inode.
+ *
+ * All other metadata changes will be passed right to the lower filesystem,
+ * and we will just update our inode to look like the lower.
+ */
+static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+	int rc = 0;
+	struct dentry *lower_dentry;
+	struct inode *inode;
+	struct inode *lower_inode;
+	struct ecryptfs_crypt_stat *crypt_stat;
+
+	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	inode = dentry->d_inode;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	if (ia->ia_valid & ATTR_SIZE) {
+		ecryptfs_printk(KERN_DEBUG,
+				"ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
+				ia->ia_valid, ATTR_SIZE);
+		rc = ecryptfs_truncate(dentry, ia->ia_size);
+		/* ecryptfs_truncate handles resizing of the lower file */
+		ia->ia_valid &= ~ATTR_SIZE;
+		ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
+				ia->ia_valid);
+		if (rc < 0)
+			goto out;
+	}
+	rc = notify_change(lower_dentry, ia);
+out:
+	ecryptfs_copy_attr_all(inode, lower_inode);
+	return rc;
+}
+
+static int
+ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		  size_t size, int flags)
+{
+	int rc = 0;
+	struct dentry *lower_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (!lower_dentry->d_inode->i_op->setxattr) {
+		rc = -ENOSYS;
+		goto out;
+	}
+	mutex_lock(&lower_dentry->d_inode->i_mutex);
+	rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
+						   size, flags);
+	mutex_unlock(&lower_dentry->d_inode->i_mutex);
+out:
+	return rc;
+}
+
+static ssize_t
+ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
+		  size_t size)
+{
+	int rc = 0;
+	struct dentry *lower_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (!lower_dentry->d_inode->i_op->getxattr) {
+		rc = -ENOSYS;
+		goto out;
+	}
+	mutex_lock(&lower_dentry->d_inode->i_mutex);
+	rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
+						   size);
+	mutex_unlock(&lower_dentry->d_inode->i_mutex);
+out:
+	return rc;
+}
+
+static ssize_t
+ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+	int rc = 0;
+	struct dentry *lower_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (!lower_dentry->d_inode->i_op->listxattr) {
+		rc = -ENOSYS;
+		goto out;
+	}
+	mutex_lock(&lower_dentry->d_inode->i_mutex);
+	rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
+	mutex_unlock(&lower_dentry->d_inode->i_mutex);
+out:
+	return rc;
+}
+
+static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
+{
+	int rc = 0;
+	struct dentry *lower_dentry;
+
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	if (!lower_dentry->d_inode->i_op->removexattr) {
+		rc = -ENOSYS;
+		goto out;
+	}
+	mutex_lock(&lower_dentry->d_inode->i_mutex);
+	rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
+	mutex_unlock(&lower_dentry->d_inode->i_mutex);
+out:
+	return rc;
+}
+
+int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
+{
+	if ((ecryptfs_inode_to_lower(inode)
+	     == (struct inode *)candidate_lower_inode))
+		return 1;
+	else
+		return 0;
+}
+
+int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
+{
+	ecryptfs_init_inode(inode, (struct inode *)lower_inode);
+	return 0;
+}
+
+struct inode_operations ecryptfs_symlink_iops = {
+	.readlink = ecryptfs_readlink,
+	.follow_link = ecryptfs_follow_link,
+	.put_link = ecryptfs_put_link,
+	.permission = ecryptfs_permission,
+	.setattr = ecryptfs_setattr,
+	.setxattr = ecryptfs_setxattr,
+	.getxattr = ecryptfs_getxattr,
+	.listxattr = ecryptfs_listxattr,
+	.removexattr = ecryptfs_removexattr
+};
+
+struct inode_operations ecryptfs_dir_iops = {
+	.create = ecryptfs_create,
+	.lookup = ecryptfs_lookup,
+	.link = ecryptfs_link,
+	.unlink = ecryptfs_unlink,
+	.symlink = ecryptfs_symlink,
+	.mkdir = ecryptfs_mkdir,
+	.rmdir = ecryptfs_rmdir,
+	.mknod = ecryptfs_mknod,
+	.rename = ecryptfs_rename,
+	.permission = ecryptfs_permission,
+	.setattr = ecryptfs_setattr,
+	.setxattr = ecryptfs_setxattr,
+	.getxattr = ecryptfs_getxattr,
+	.listxattr = ecryptfs_listxattr,
+	.removexattr = ecryptfs_removexattr
+};
+
+struct inode_operations ecryptfs_main_iops = {
+	.permission = ecryptfs_permission,
+	.setattr = ecryptfs_setattr,
+	.setxattr = ecryptfs_setxattr,
+	.getxattr = ecryptfs_getxattr,
+	.listxattr = ecryptfs_listxattr,
+	.removexattr = ecryptfs_removexattr
+};

fs/ecryptfs/keystore.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * In-kernel key management code.  Includes functions to parse and
+ * write authentication token-related packets with the underlying
+ * file.
+ *
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *              Michael C. Thompson <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/string.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/pagemap.h>
+#include <linux/key.h>
+#include <linux/random.h>
+#include <linux/crypto.h>
+#include <linux/scatterlist.h>
+#include "ecryptfs_kernel.h"
+
+/**
+ * request_key returned an error instead of a valid key address;
+ * determine the type of error, make appropriate log entries, and
+ * return an error code.
+ */
+int process_request_key_err(long err_code)
+{
+	int rc = 0;
+
+	switch (err_code) {
+	case ENOKEY:
+		ecryptfs_printk(KERN_WARNING, "No key\n");
+		rc = -ENOENT;
+		break;
+	case EKEYEXPIRED:
+		ecryptfs_printk(KERN_WARNING, "Key expired\n");
+		rc = -ETIME;
+		break;
+	case EKEYREVOKED:
+		ecryptfs_printk(KERN_WARNING, "Key revoked\n");
+		rc = -EINVAL;
+		break;
+	default:
+		ecryptfs_printk(KERN_WARNING, "Unknown error code: "
+				"[0x%.16x]\n", err_code);
+		rc = -EINVAL;
+	}
+	return rc;
+}
+
+static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
+{
+	struct list_head *walker;
+	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
+
+	walker = auth_tok_list_head->next;
+	while (walker != auth_tok_list_head) {
+		auth_tok_list_item =
+		    list_entry(walker, struct ecryptfs_auth_tok_list_item,
+			       list);
+		walker = auth_tok_list_item->list.next;
+		memset(auth_tok_list_item, 0,
+		       sizeof(struct ecryptfs_auth_tok_list_item));
+		kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
+				auth_tok_list_item);
+	}
+}
+
+struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
+
+/**
+ * parse_packet_length
+ * @data: Pointer to memory containing length at offset
+ * @size: This function writes the decoded size to this memory
+ *        address; zero on error
+ * @length_size: The number of bytes occupied by the encoded length
+ *
+ * Returns Zero on success
+ */
+static int parse_packet_length(unsigned char *data, size_t *size,
+			       size_t *length_size)
+{
+	int rc = 0;
+
+	(*length_size) = 0;
+	(*size) = 0;
+	if (data[0] < 192) {
+		/* One-byte length */
+		(*size) = data[0];
+		(*length_size) = 1;
+	} else if (data[0] < 224) {
+		/* Two-byte length */
+		(*size) = ((data[0] - 192) * 256);
+		(*size) += (data[1] + 192);
+		(*length_size) = 2;
+	} else if (data[0] == 255) {
+		/* Five-byte length; we're not supposed to see this */
+		ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
+				"supported\n");
+		rc = -EINVAL;
+		goto out;
+	} else {
+		ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
+		rc = -EINVAL;
+		goto out;
+	}
+out:
+	return rc;
+}
+
+/**
+ * write_packet_length
+ * @dest: The byte array target into which to write the
+ *       length. Must have at least 5 bytes allocated.
+ * @size: The length to write.
+ * @packet_size_length: The number of bytes used to encode the
+ *                      packet length is written to this address.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int write_packet_length(char *dest, size_t size,
+			       size_t *packet_size_length)
+{
+	int rc = 0;
+
+	if (size < 192) {
+		dest[0] = size;
+		(*packet_size_length) = 1;
+	} else if (size < 65536) {
+		dest[0] = (((size - 192) / 256) + 192);
+		dest[1] = ((size - 192) % 256);
+		(*packet_size_length) = 2;
+	} else {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_WARNING,
+				"Unsupported packet size: [%d]\n", size);
+	}
+	return rc;
+}
+
+/**
+ * parse_tag_3_packet
+ * @crypt_stat: The cryptographic context to modify based on packet
+ *              contents.
+ * @data: The raw bytes of the packet.
+ * @auth_tok_list: eCryptfs parses packets into authentication tokens;
+ *                 a new authentication token will be placed at the end
+ *                 of this list for this packet.
+ * @new_auth_tok: Pointer to a pointer to memory that this function
+ *                allocates; sets the memory address of the pointer to
+ *                NULL on error. This object is added to the
+ *                auth_tok_list.
+ * @packet_size: This function writes the size of the parsed packet
+ *               into this memory location; zero on error.
+ * @max_packet_size: maximum number of bytes to parse
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
+		   unsigned char *data, struct list_head *auth_tok_list,
+		   struct ecryptfs_auth_tok **new_auth_tok,
+		   size_t *packet_size, size_t max_packet_size)
+{
+	int rc = 0;
+	size_t body_size;
+	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
+	size_t length_size;
+
+	(*packet_size) = 0;
+	(*new_auth_tok) = NULL;
+
+	/* we check that:
+	 *   one byte for the Tag 3 ID flag
+	 *   two bytes for the body size
+	 * do not exceed the maximum_packet_size
+	 */
+	if (unlikely((*packet_size) + 3 > max_packet_size)) {
+		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* check for Tag 3 identifyer - one byte */
+	if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
+		ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
+				ECRYPTFS_TAG_3_PACKET_TYPE);
+		rc = -EINVAL;
+		goto out;
+	}
+	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
+	 * at end of function upon failure */
+	auth_tok_list_item =
+	    kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache, SLAB_KERNEL);
+	if (!auth_tok_list_item) {
+		ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	memset(auth_tok_list_item, 0,
+	       sizeof(struct ecryptfs_auth_tok_list_item));
+	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
+
+	/* check for body size - one to two bytes */
+	rc = parse_packet_length(&data[(*packet_size)], &body_size,
+				 &length_size);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
+				"rc = [%d]\n", rc);
+		goto out_free;
+	}
+	if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) {
+		ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
+				body_size);
+		rc = -EINVAL;
+		goto out_free;
+	}
+	(*packet_size) += length_size;
+
+	/* now we know the length of the remainting Tag 3 packet size:
+	 *   5 fix bytes for: version string, cipher, S2K ID, hash algo,
+	 *                    number of hash iterations
+	 *   ECRYPTFS_SALT_SIZE bytes for salt
+	 *   body_size bytes minus the stuff above is the encrypted key size
+	 */
+	if (unlikely((*packet_size) + body_size > max_packet_size)) {
+		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+		rc = -EINVAL;
+		goto out_free;
+	}
+
+	/* There are 5 characters of additional information in the
+	 * packet */
+	(*new_auth_tok)->session_key.encrypted_key_size =
+		body_size - (0x05 + ECRYPTFS_SALT_SIZE);
+	ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
+			(*new_auth_tok)->session_key.encrypted_key_size);
+
+	/* Version 4 (from RFC2440) - one byte */
+	if (unlikely(data[(*packet_size)++] != 0x04)) {
+		ecryptfs_printk(KERN_DEBUG, "Unknown version number "
+				"[%d]\n", data[(*packet_size) - 1]);
+		rc = -EINVAL;
+		goto out_free;
+	}
+
+	/* cipher - one byte */
+	ecryptfs_cipher_code_to_string(crypt_stat->cipher,
+				       (u16)data[(*packet_size)]);
+	/* A little extra work to differentiate among the AES key
+	 * sizes; see RFC2440 */
+	switch(data[(*packet_size)++]) {
+	case RFC2440_CIPHER_AES_192:
+		crypt_stat->key_size = 24;
+		break;
+	default:
+		crypt_stat->key_size =
+			(*new_auth_tok)->session_key.encrypted_key_size;
+	}
+	ecryptfs_init_crypt_ctx(crypt_stat);
+	/* S2K identifier 3 (from RFC2440) */
+	if (unlikely(data[(*packet_size)++] != 0x03)) {
+		ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
+				"supported\n");
+		rc = -ENOSYS;
+		goto out_free;
+	}
+
+	/* TODO: finish the hash mapping */
+	/* hash algorithm - one byte */
+	switch (data[(*packet_size)++]) {
+	case 0x01: /* See RFC2440 for these numbers and their mappings */
+		/* Choose MD5 */
+		/* salt - ECRYPTFS_SALT_SIZE bytes */
+		memcpy((*new_auth_tok)->token.password.salt,
+		       &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
+		(*packet_size) += ECRYPTFS_SALT_SIZE;
+
+		/* This conversion was taken straight from RFC2440 */
+		/* number of hash iterations - one byte */
+		(*new_auth_tok)->token.password.hash_iterations =
+			((u32) 16 + (data[(*packet_size)] & 15))
+				<< ((data[(*packet_size)] >> 4) + 6);
+		(*packet_size)++;
+
+		/* encrypted session key -
+		 *   (body_size-5-ECRYPTFS_SALT_SIZE) bytes */
+		memcpy((*new_auth_tok)->session_key.encrypted_key,
+		       &data[(*packet_size)],
+		       (*new_auth_tok)->session_key.encrypted_key_size);
+		(*packet_size) +=
+			(*new_auth_tok)->session_key.encrypted_key_size;
+		(*new_auth_tok)->session_key.flags &=
+			~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
+		(*new_auth_tok)->session_key.flags |=
+			ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
+		(*new_auth_tok)->token.password.hash_algo = 0x01;
+		break;
+	default:
+		ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
+				"[%d]\n", data[(*packet_size) - 1]);
+		rc = -ENOSYS;
+		goto out_free;
+	}
+	(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
+	/* TODO: Parametarize; we might actually want userspace to
+	 * decrypt the session key. */
+	ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
+			    ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
+	ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
+			    ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
+	list_add(&auth_tok_list_item->list, auth_tok_list);
+	goto out;
+out_free:
+	(*new_auth_tok) = NULL;
+	memset(auth_tok_list_item, 0,
+	       sizeof(struct ecryptfs_auth_tok_list_item));
+	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
+			auth_tok_list_item);
+out:
+	if (rc)
+		(*packet_size) = 0;
+	return rc;
+}
+
+/**
+ * parse_tag_11_packet
+ * @data: The raw bytes of the packet
+ * @contents: This function writes the data contents of the literal
+ *            packet into this memory location
+ * @max_contents_bytes: The maximum number of bytes that this function
+ *                      is allowed to write into contents
+ * @tag_11_contents_size: This function writes the size of the parsed
+ *                        contents into this memory location; zero on
+ *                        error
+ * @packet_size: This function writes the size of the parsed packet
+ *               into this memory location; zero on error
+ * @max_packet_size: maximum number of bytes to parse
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+parse_tag_11_packet(unsigned char *data, unsigned char *contents,
+		    size_t max_contents_bytes, size_t *tag_11_contents_size,
+		    size_t *packet_size, size_t max_packet_size)
+{
+	int rc = 0;
+	size_t body_size;
+	size_t length_size;
+
+	(*packet_size) = 0;
+	(*tag_11_contents_size) = 0;
+
+	/* check that:
+	 *   one byte for the Tag 11 ID flag
+	 *   two bytes for the Tag 11 length
+	 * do not exceed the maximum_packet_size
+	 */
+	if (unlikely((*packet_size) + 3 > max_packet_size)) {
+		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* check for Tag 11 identifyer - one byte */
+	if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
+		ecryptfs_printk(KERN_WARNING,
+				"Invalid tag 11 packet format\n");
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* get Tag 11 content length - one or two bytes */
+	rc = parse_packet_length(&data[(*packet_size)], &body_size,
+				 &length_size);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING,
+				"Invalid tag 11 packet format\n");
+		goto out;
+	}
+	(*packet_size) += length_size;
+
+	if (body_size < 13) {
+		ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
+				body_size);
+		rc = -EINVAL;
+		goto out;
+	}
+	/* We have 13 bytes of surrounding packet values */
+	(*tag_11_contents_size) = (body_size - 13);
+
+	/* now we know the length of the remainting Tag 11 packet size:
+	 *   14 fix bytes for: special flag one, special flag two,
+	 *   		       12 skipped bytes
+	 *   body_size bytes minus the stuff above is the Tag 11 content
+	 */
+	/* FIXME why is the body size one byte smaller than the actual
+	 * size of the body?
+	 * this seems to be an error here as well as in
+	 * write_tag_11_packet() */
+	if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
+		ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* special flag one - one byte */
+	if (data[(*packet_size)++] != 0x62) {
+		ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* special flag two - one byte */
+	if (data[(*packet_size)++] != 0x08) {
+		ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* skip the next 12 bytes */
+	(*packet_size) += 12; /* We don't care about the filename or
+			       * the timestamp */
+
+	/* get the Tag 11 contents - tag_11_contents_size bytes */
+	memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
+	(*packet_size) += (*tag_11_contents_size);
+
+out:
+	if (rc) {
+		(*packet_size) = 0;
+		(*tag_11_contents_size) = 0;
+	}
+	return rc;
+}
+
+/**
+ * decrypt_session_key - Decrypt the session key with the given auth_tok.
+ *
+ * Returns Zero on success; non-zero error otherwise.
+ */
+static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
+			       struct ecryptfs_crypt_stat *crypt_stat)
+{
+	int rc = 0;
+	struct ecryptfs_password *password_s_ptr;
+	struct crypto_tfm *tfm = NULL;
+	struct scatterlist src_sg[2], dst_sg[2];
+	struct mutex *tfm_mutex = NULL;
+	/* TODO: Use virt_to_scatterlist for these */
+	char *encrypted_session_key;
+	char *session_key;
+
+	password_s_ptr = &auth_tok->token.password;
+	if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags,
+				ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET))
+		ecryptfs_printk(KERN_DEBUG, "Session key encryption key "
+				"set; skipping key generation\n");
+	ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])"
+			":\n",
+			password_s_ptr->session_key_encryption_key_bytes);
+	if (ecryptfs_verbosity > 0)
+		ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key,
+				  password_s_ptr->
+				  session_key_encryption_key_bytes);
+	if (!strcmp(crypt_stat->cipher,
+		    crypt_stat->mount_crypt_stat->global_default_cipher_name)
+	    && crypt_stat->mount_crypt_stat->global_key_tfm) {
+		tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
+		tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
+	} else {
+		tfm = crypto_alloc_tfm(crypt_stat->cipher,
+				       CRYPTO_TFM_REQ_WEAK_KEY);
+		if (!tfm) {
+			printk(KERN_ERR "Error allocating crypto context\n");
+			rc = -ENOMEM;
+			goto out;
+		}
+	}
+	if (password_s_ptr->session_key_encryption_key_bytes
+	    < crypto_tfm_alg_min_keysize(tfm)) {
+		printk(KERN_WARNING "Session key encryption key is [%d] bytes; "
+		       "minimum keysize for selected cipher is [%d] bytes.\n",
+		       password_s_ptr->session_key_encryption_key_bytes,
+		       crypto_tfm_alg_min_keysize(tfm));
+		rc = -EINVAL;
+		goto out;
+	}
+	if (tfm_mutex)
+		mutex_lock(tfm_mutex);
+	crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key,
+			     crypt_stat->key_size);
+	/* TODO: virt_to_scatterlist */
+	encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
+	if (!encrypted_session_key) {
+		ecryptfs_printk(KERN_ERR, "Out of memory\n");
+		rc = -ENOMEM;
+		goto out_free_tfm;
+	}
+	session_key = (char *)__get_free_page(GFP_KERNEL);
+	if (!session_key) {
+		kfree(encrypted_session_key);
+		ecryptfs_printk(KERN_ERR, "Out of memory\n");
+		rc = -ENOMEM;
+		goto out_free_tfm;
+	}
+	memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key,
+	       auth_tok->session_key.encrypted_key_size);
+	src_sg[0].page = virt_to_page(encrypted_session_key);
+	src_sg[0].offset = 0;
+	BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE);
+	src_sg[0].length = auth_tok->session_key.encrypted_key_size;
+	dst_sg[0].page = virt_to_page(session_key);
+	dst_sg[0].offset = 0;
+	auth_tok->session_key.decrypted_key_size =
+	    auth_tok->session_key.encrypted_key_size;
+	dst_sg[0].length = auth_tok->session_key.encrypted_key_size;
+	/* TODO: Handle error condition */
+	crypto_cipher_decrypt(tfm, dst_sg, src_sg,
+			      auth_tok->session_key.encrypted_key_size);
+	auth_tok->session_key.decrypted_key_size =
+	    auth_tok->session_key.encrypted_key_size;
+	memcpy(auth_tok->session_key.decrypted_key, session_key,
+	       auth_tok->session_key.decrypted_key_size);
+	auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
+	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
+	       auth_tok->session_key.decrypted_key_size);
+	ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
+	ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
+	if (ecryptfs_verbosity > 0)
+		ecryptfs_dump_hex(crypt_stat->key,
+				  crypt_stat->key_size);
+	memset(encrypted_session_key, 0, PAGE_CACHE_SIZE);
+	free_page((unsigned long)encrypted_session_key);
+	memset(session_key, 0, PAGE_CACHE_SIZE);
+	free_page((unsigned long)session_key);
+out_free_tfm:
+	if (tfm_mutex)
+		mutex_unlock(tfm_mutex);
+	else
+		crypto_free_tfm(tfm);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_parse_packet_set
+ * @dest: The header page in memory
+ * @version: Version of file format, to guide parsing behavior
+ *
+ * Get crypt_stat to have the file's session key if the requisite key
+ * is available to decrypt the session key.
+ *
+ * Returns Zero if a valid authentication token was retrieved and
+ * processed; negative value for file not encrypted or for error
+ * conditions.
+ */
+int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
+			      unsigned char *src,
+			      struct dentry *ecryptfs_dentry)
+{
+	size_t i = 0;
+	int rc = 0;
+	size_t found_auth_tok = 0;
+	size_t next_packet_is_auth_tok_packet;
+	char sig[ECRYPTFS_SIG_SIZE_HEX];
+	struct list_head auth_tok_list;
+	struct list_head *walker;
+	struct ecryptfs_auth_tok *chosen_auth_tok = NULL;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+		&ecryptfs_superblock_to_private(
+			ecryptfs_dentry->d_sb)->mount_crypt_stat;
+	struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
+	size_t packet_size;
+	struct ecryptfs_auth_tok *new_auth_tok;
+	unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
+	size_t tag_11_contents_size;
+	size_t tag_11_packet_size;
+
+	INIT_LIST_HEAD(&auth_tok_list);
+	/* Parse the header to find as many packets as we can, these will be
+	 * added the our &auth_tok_list */
+	next_packet_is_auth_tok_packet = 1;
+	while (next_packet_is_auth_tok_packet) {
+		size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
+
+		switch (src[i]) {
+		case ECRYPTFS_TAG_3_PACKET_TYPE:
+			rc = parse_tag_3_packet(crypt_stat,
+						(unsigned char *)&src[i],
+						&auth_tok_list, &new_auth_tok,
+						&packet_size, max_packet_size);
+			if (rc) {
+				ecryptfs_printk(KERN_ERR, "Error parsing "
+						"tag 3 packet\n");
+				rc = -EIO;
+				goto out_wipe_list;
+			}
+			i += packet_size;
+			rc = parse_tag_11_packet((unsigned char *)&src[i],
+						 sig_tmp_space,
+						 ECRYPTFS_SIG_SIZE,
+						 &tag_11_contents_size,
+						 &tag_11_packet_size,
+						 max_packet_size);
+			if (rc) {
+				ecryptfs_printk(KERN_ERR, "No valid "
+						"(ecryptfs-specific) literal "
+						"packet containing "
+						"authentication token "
+						"signature found after "
+						"tag 3 packet\n");
+				rc = -EIO;
+				goto out_wipe_list;
+			}
+			i += tag_11_packet_size;
+			if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
+				ecryptfs_printk(KERN_ERR, "Expected "
+						"signature of size [%d]; "
+						"read size [%d]\n",
+						ECRYPTFS_SIG_SIZE,
+						tag_11_contents_size);
+				rc = -EIO;
+				goto out_wipe_list;
+			}
+			ecryptfs_to_hex(new_auth_tok->token.password.signature,
+					sig_tmp_space, tag_11_contents_size);
+			new_auth_tok->token.password.signature[
+				ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
+			ECRYPTFS_SET_FLAG(crypt_stat->flags,
+					  ECRYPTFS_ENCRYPTED);
+			break;
+		case ECRYPTFS_TAG_11_PACKET_TYPE:
+			ecryptfs_printk(KERN_WARNING, "Invalid packet set "
+					"(Tag 11 not allowed by itself)\n");
+			rc = -EIO;
+			goto out_wipe_list;
+			break;
+		default:
+			ecryptfs_printk(KERN_DEBUG, "No packet at offset "
+					"[%d] of the file header; hex value of "
+					"character is [0x%.2x]\n", i, src[i]);
+			next_packet_is_auth_tok_packet = 0;
+		}
+	}
+	if (list_empty(&auth_tok_list)) {
+		rc = -EINVAL; /* Do not support non-encrypted files in
+			       * the 0.1 release */
+		goto out;
+	}
+	/* If we have a global auth tok, then we should try to use
+	 * it */
+	if (mount_crypt_stat->global_auth_tok) {
+		memcpy(sig, mount_crypt_stat->global_auth_tok_sig,
+		       ECRYPTFS_SIG_SIZE_HEX);
+		chosen_auth_tok = mount_crypt_stat->global_auth_tok;
+	} else
+		BUG(); /* We should always have a global auth tok in
+			* the 0.1 release */
+	/* Scan list to see if our chosen_auth_tok works */
+	list_for_each(walker, &auth_tok_list) {
+		struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
+		auth_tok_list_item =
+		    list_entry(walker, struct ecryptfs_auth_tok_list_item,
+			       list);
+		candidate_auth_tok = &auth_tok_list_item->auth_tok;
+		if (unlikely(ecryptfs_verbosity > 0)) {
+			ecryptfs_printk(KERN_DEBUG,
+					"Considering cadidate auth tok:\n");
+			ecryptfs_dump_auth_tok(candidate_auth_tok);
+		}
+		/* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */
+		if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD
+		    && !strncmp(candidate_auth_tok->token.password.signature,
+				sig, ECRYPTFS_SIG_SIZE_HEX)) {
+			found_auth_tok = 1;
+			goto leave_list;
+			/* TODO: Transfer the common salt into the
+			 * crypt_stat salt */
+		}
+	}
+leave_list:
+	if (!found_auth_tok) {
+		ecryptfs_printk(KERN_ERR, "Could not find authentication "
+				"token on temporary list for sig [%.*s]\n",
+				ECRYPTFS_SIG_SIZE_HEX, sig);
+		rc = -EIO;
+		goto out_wipe_list;
+	} else {
+		memcpy(&(candidate_auth_tok->token.password),
+		       &(chosen_auth_tok->token.password),
+		       sizeof(struct ecryptfs_password));
+		rc = decrypt_session_key(candidate_auth_tok, crypt_stat);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error decrypting the "
+					"session key\n");
+			goto out_wipe_list;
+		}
+		rc = ecryptfs_compute_root_iv(crypt_stat);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error computing "
+					"the root IV\n");
+			goto out_wipe_list;
+		}
+	}
+	rc = ecryptfs_init_crypt_ctx(crypt_stat);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error initializing crypto "
+				"context for cipher [%s]; rc = [%d]\n",
+				crypt_stat->cipher, rc);
+	}
+out_wipe_list:
+	wipe_auth_tok_list(&auth_tok_list);
+out:
+	return rc;
+}
+
+/**
+ * write_tag_11_packet
+ * @dest: Target into which Tag 11 packet is to be written
+ * @max: Maximum packet length
+ * @contents: Byte array of contents to copy in
+ * @contents_length: Number of bytes in contents
+ * @packet_length: Length of the Tag 11 packet written; zero on error
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length,
+		    size_t *packet_length)
+{
+	int rc = 0;
+	size_t packet_size_length;
+
+	(*packet_length) = 0;
+	if ((13 + contents_length) > max) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_ERR, "Packet length larger than "
+				"maximum allowable\n");
+		goto out;
+	}
+	/* General packet header */
+	/* Packet tag */
+	dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
+	/* Packet length */
+	rc = write_packet_length(&dest[(*packet_length)],
+				 (13 + contents_length), &packet_size_length);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
+				"header; cannot generate packet length\n");
+		goto out;
+	}
+	(*packet_length) += packet_size_length;
+	/* Tag 11 specific */
+	/* One-octet field that describes how the data is formatted */
+	dest[(*packet_length)++] = 0x62; /* binary data */
+	/* One-octet filename length followed by filename */
+	dest[(*packet_length)++] = 8;
+	memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
+	(*packet_length) += 8;
+	/* Four-octet number indicating modification date */
+	memset(&dest[(*packet_length)], 0x00, 4);
+	(*packet_length) += 4;
+	/* Remainder is literal data */
+	memcpy(&dest[(*packet_length)], contents, contents_length);
+	(*packet_length) += contents_length;
+ out:
+	if (rc)
+		(*packet_length) = 0;
+	return rc;
+}
+
+/**
+ * write_tag_3_packet
+ * @dest: Buffer into which to write the packet
+ * @max: Maximum number of bytes that can be written
+ * @auth_tok: Authentication token
+ * @crypt_stat: The cryptographic context
+ * @key_rec: encrypted key
+ * @packet_size: This function will write the number of bytes that end
+ *               up constituting the packet; set to zero on error
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+write_tag_3_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok,
+		   struct ecryptfs_crypt_stat *crypt_stat,
+		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
+{
+	int rc = 0;
+
+	size_t i;
+	size_t signature_is_valid = 0;
+	size_t encrypted_session_key_valid = 0;
+	char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
+	struct scatterlist dest_sg[2];
+	struct scatterlist src_sg[2];
+	struct crypto_tfm *tfm = NULL;
+	struct mutex *tfm_mutex = NULL;
+	size_t key_rec_size;
+	size_t packet_size_length;
+	size_t cipher_code;
+
+	(*packet_size) = 0;
+	/* Check for a valid signature on the auth_tok */
+	for (i = 0; i < ECRYPTFS_SIG_SIZE_HEX; i++)
+		signature_is_valid |= auth_tok->token.password.signature[i];
+	if (!signature_is_valid)
+		BUG();
+	ecryptfs_from_hex((*key_rec).sig, auth_tok->token.password.signature,
+			  ECRYPTFS_SIG_SIZE);
+	encrypted_session_key_valid = 0;
+	for (i = 0; i < crypt_stat->key_size; i++)
+		encrypted_session_key_valid |=
+			auth_tok->session_key.encrypted_key[i];
+	if (encrypted_session_key_valid) {
+		memcpy((*key_rec).enc_key,
+		       auth_tok->session_key.encrypted_key,
+		       auth_tok->session_key.encrypted_key_size);
+		goto encrypted_session_key_set;
+	}
+	if (auth_tok->session_key.encrypted_key_size == 0)
+		auth_tok->session_key.encrypted_key_size =
+			crypt_stat->key_size;
+	if (crypt_stat->key_size == 24
+	    && strcmp("aes", crypt_stat->cipher) == 0) {
+		memset((crypt_stat->key + 24), 0, 8);
+		auth_tok->session_key.encrypted_key_size = 32;
+	}
+	(*key_rec).enc_key_size =
+		auth_tok->session_key.encrypted_key_size;
+	if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags,
+				ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) {
+		ecryptfs_printk(KERN_DEBUG, "Using previously generated "
+				"session key encryption key of size [%d]\n",
+				auth_tok->token.password.
+				session_key_encryption_key_bytes);
+		memcpy(session_key_encryption_key,
+		       auth_tok->token.password.session_key_encryption_key,
+		       crypt_stat->key_size);
+		ecryptfs_printk(KERN_DEBUG,
+				"Cached session key " "encryption key: \n");
+		if (ecryptfs_verbosity > 0)
+			ecryptfs_dump_hex(session_key_encryption_key, 16);
+	}
+	if (unlikely(ecryptfs_verbosity > 0)) {
+		ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
+		ecryptfs_dump_hex(session_key_encryption_key, 16);
+	}
+	rc = virt_to_scatterlist(crypt_stat->key,
+				 (*key_rec).enc_key_size, src_sg, 2);
+	if (!rc) {
+		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
+				"for crypt_stat session key\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	rc = virt_to_scatterlist((*key_rec).enc_key,
+				 (*key_rec).enc_key_size, dest_sg, 2);
+	if (!rc) {
+		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
+				"for crypt_stat encrypted session key\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	if (!strcmp(crypt_stat->cipher,
+		    crypt_stat->mount_crypt_stat->global_default_cipher_name)
+	    && crypt_stat->mount_crypt_stat->global_key_tfm) {
+		tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
+		tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
+	} else
+		tfm = crypto_alloc_tfm(crypt_stat->cipher, 0);
+	if (!tfm) {
+		ecryptfs_printk(KERN_ERR, "Could not initialize crypto "
+				"context for cipher [%s]\n",
+				crypt_stat->cipher);
+		rc = -EINVAL;
+		goto out;
+	}
+	if (tfm_mutex)
+		mutex_lock(tfm_mutex);
+	rc = crypto_cipher_setkey(tfm, session_key_encryption_key,
+				  crypt_stat->key_size);
+	if (rc < 0) {
+		if (tfm_mutex)
+			mutex_unlock(tfm_mutex);
+		ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
+				"context\n");
+		goto out;
+	}
+	rc = 0;
+	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
+			crypt_stat->key_size);
+	crypto_cipher_encrypt(tfm, dest_sg, src_sg,
+			      (*key_rec).enc_key_size);
+	if (tfm_mutex)
+		mutex_unlock(tfm_mutex);
+	ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
+	if (ecryptfs_verbosity > 0)
+		ecryptfs_dump_hex((*key_rec).enc_key,
+				  (*key_rec).enc_key_size);
+encrypted_session_key_set:
+	/* Now we have a valid key_rec.  Append it to the
+	 * key_rec set. */
+	key_rec_size = (sizeof(struct ecryptfs_key_record)
+			- ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
+			+ ((*key_rec).enc_key_size));
+	/* TODO: Include a packet size limit as a parameter to this
+	 * function once we have multi-packet headers (for versions
+	 * later than 0.1 */
+	if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
+		ecryptfs_printk(KERN_ERR, "Keyset too large\n");
+		rc = -EINVAL;
+		goto out;
+	}
+	/* TODO: Packet size limit */
+	/* We have 5 bytes of surrounding packet data */
+	if ((0x05 + ECRYPTFS_SALT_SIZE
+	     + (*key_rec).enc_key_size) >= max) {
+		ecryptfs_printk(KERN_ERR, "Authentication token is too "
+				"large\n");
+		rc = -EINVAL;
+		goto out;
+	}
+	/* This format is inspired by OpenPGP; see RFC 2440
+	 * packet tag 3 */
+	dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
+	/* ver+cipher+s2k+hash+salt+iter+enc_key */
+	rc = write_packet_length(&dest[(*packet_size)],
+				 (0x05 + ECRYPTFS_SALT_SIZE
+				  + (*key_rec).enc_key_size),
+				 &packet_size_length);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet "
+				"header; cannot generate packet length\n");
+		goto out;
+	}
+	(*packet_size) += packet_size_length;
+	dest[(*packet_size)++] = 0x04; /* version 4 */
+	cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
+	if (cipher_code == 0) {
+		ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
+				"cipher [%s]\n", crypt_stat->cipher);
+		rc = -EINVAL;
+		goto out;
+	}
+	dest[(*packet_size)++] = cipher_code;
+	dest[(*packet_size)++] = 0x03;	/* S2K */
+	dest[(*packet_size)++] = 0x01;	/* MD5 (TODO: parameterize) */
+	memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
+	       ECRYPTFS_SALT_SIZE);
+	(*packet_size) += ECRYPTFS_SALT_SIZE;	/* salt */
+	dest[(*packet_size)++] = 0x60;	/* hash iterations (65536) */
+	memcpy(&dest[(*packet_size)], (*key_rec).enc_key,
+	       (*key_rec).enc_key_size);
+	(*packet_size) += (*key_rec).enc_key_size;
+out:
+	if (tfm && !tfm_mutex)
+		crypto_free_tfm(tfm);
+	if (rc)
+		(*packet_size) = 0;
+	return rc;
+}
+
+/**
+ * ecryptfs_generate_key_packet_set
+ * @dest: Virtual address from which to write the key record set
+ * @crypt_stat: The cryptographic context from which the
+ *              authentication tokens will be retrieved
+ * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
+ *                   for the global parameters
+ * @len: The amount written
+ * @max: The maximum amount of data allowed to be written
+ *
+ * Generates a key packet set and writes it to the virtual address
+ * passed in.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+int
+ecryptfs_generate_key_packet_set(char *dest_base,
+				 struct ecryptfs_crypt_stat *crypt_stat,
+				 struct dentry *ecryptfs_dentry, size_t *len,
+				 size_t max)
+{
+	int rc = 0;
+	struct ecryptfs_auth_tok *auth_tok;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+		&ecryptfs_superblock_to_private(
+			ecryptfs_dentry->d_sb)->mount_crypt_stat;
+	size_t written;
+	struct ecryptfs_key_record key_rec;
+
+	(*len) = 0;
+	if (mount_crypt_stat->global_auth_tok) {
+		auth_tok = mount_crypt_stat->global_auth_tok;
+		if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
+			rc = write_tag_3_packet((dest_base + (*len)),
+						max, auth_tok,
+						crypt_stat, &key_rec,
+						&written);
+			if (rc) {
+				ecryptfs_printk(KERN_WARNING, "Error "
+						"writing tag 3 packet\n");
+				goto out;
+			}
+			(*len) += written;
+			/* Write auth tok signature packet */
+			rc = write_tag_11_packet(
+				(dest_base + (*len)),
+				(max - (*len)),
+				key_rec.sig, ECRYPTFS_SIG_SIZE, &written);
+			if (rc) {
+				ecryptfs_printk(KERN_ERR, "Error writing "
+						"auth tok signature packet\n");
+				goto out;
+			}
+			(*len) += written;
+		} else {
+			ecryptfs_printk(KERN_WARNING, "Unsupported "
+					"authentication token type\n");
+			rc = -EINVAL;
+			goto out;
+		}
+		if (rc) {
+			ecryptfs_printk(KERN_WARNING, "Error writing "
+					"authentication token packet with sig "
+					"= [%s]\n",
+					mount_crypt_stat->global_auth_tok_sig);
+			rc = -EIO;
+			goto out;
+		}
+	} else
+		BUG();
+	if (likely((max - (*len)) > 0)) {
+		dest_base[(*len)] = 0x00;
+	} else {
+		ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
+		rc = -EIO;
+	}
+out:
+	if (rc)
+		(*len) = 0;
+	return rc;
+}

fs/ecryptfs/main.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *              Michael C. Thompson <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/dcache.h>
+#include <linux/file.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/skbuff.h>
+#include <linux/crypto.h>
+#include <linux/netlink.h>
+#include <linux/mount.h>
+#include <linux/dcache.h>
+#include <linux/pagemap.h>
+#include <linux/key.h>
+#include <linux/parser.h>
+#include "ecryptfs_kernel.h"
+
+/**
+ * Module parameter that defines the ecryptfs_verbosity level.
+ */
+int ecryptfs_verbosity = 0;
+
+module_param(ecryptfs_verbosity, int, 0);
+MODULE_PARM_DESC(ecryptfs_verbosity,
+		 "Initial verbosity level (0 or 1; defaults to "
+		 "0, which is Quiet)");
+
+void __ecryptfs_printk(const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	if (fmt[1] == '7') { /* KERN_DEBUG */
+		if (ecryptfs_verbosity >= 1)
+			vprintk(fmt, args);
+	} else
+		vprintk(fmt, args);
+	va_end(args);
+}
+
+/**
+ * ecryptfs_interpose
+ * @lower_dentry: Existing dentry in the lower filesystem
+ * @dentry: ecryptfs' dentry
+ * @sb: ecryptfs's super_block
+ * @flag: If set to true, then d_add is called, else d_instantiate is called
+ *
+ * Interposes upper and lower dentries.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
+		       struct super_block *sb, int flag)
+{
+	struct inode *lower_inode;
+	struct inode *inode;
+	int rc = 0;
+
+	lower_inode = lower_dentry->d_inode;
+	if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb)) {
+		rc = -EXDEV;
+		goto out;
+	}
+	if (!igrab(lower_inode)) {
+		rc = -ESTALE;
+		goto out;
+	}
+	inode = iget5_locked(sb, (unsigned long)lower_inode,
+			     ecryptfs_inode_test, ecryptfs_inode_set,
+			     lower_inode);
+	if (!inode) {
+		rc = -EACCES;
+		iput(lower_inode);
+		goto out;
+	}
+	if (inode->i_state & I_NEW)
+		unlock_new_inode(inode);
+	else
+		iput(lower_inode);
+	if (S_ISLNK(lower_inode->i_mode))
+		inode->i_op = &ecryptfs_symlink_iops;
+	else if (S_ISDIR(lower_inode->i_mode))
+		inode->i_op = &ecryptfs_dir_iops;
+	if (S_ISDIR(lower_inode->i_mode))
+		inode->i_fop = &ecryptfs_dir_fops;
+	/* TODO: Is there a better way to identify if the inode is
+	 * special? */
+	if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) ||
+	    S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode))
+		init_special_inode(inode, lower_inode->i_mode,
+				   lower_inode->i_rdev);
+	dentry->d_op = &ecryptfs_dops;
+	if (flag)
+		d_add(dentry, inode);
+	else
+		d_instantiate(dentry, inode);
+	ecryptfs_copy_attr_all(inode, lower_inode);
+	/* This size will be overwritten for real files w/ headers and
+	 * other metadata */
+	ecryptfs_copy_inode_size(inode, lower_inode);
+out:
+	return rc;
+}
+
+enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig, ecryptfs_opt_debug,
+       ecryptfs_opt_ecryptfs_debug, ecryptfs_opt_cipher,
+       ecryptfs_opt_ecryptfs_cipher, ecryptfs_opt_ecryptfs_key_bytes,
+       ecryptfs_opt_passthrough, ecryptfs_opt_err };
+
+static match_table_t tokens = {
+	{ecryptfs_opt_sig, "sig=%s"},
+	{ecryptfs_opt_ecryptfs_sig, "ecryptfs_sig=%s"},
+	{ecryptfs_opt_debug, "debug=%u"},
+	{ecryptfs_opt_ecryptfs_debug, "ecryptfs_debug=%u"},
+	{ecryptfs_opt_cipher, "cipher=%s"},
+	{ecryptfs_opt_ecryptfs_cipher, "ecryptfs_cipher=%s"},
+	{ecryptfs_opt_ecryptfs_key_bytes, "ecryptfs_key_bytes=%u"},
+	{ecryptfs_opt_passthrough, "ecryptfs_passthrough"},
+	{ecryptfs_opt_err, NULL}
+};
+
+/**
+ * ecryptfs_verify_version
+ * @version: The version number to confirm
+ *
+ * Returns zero on good version; non-zero otherwise
+ */
+static int ecryptfs_verify_version(u16 version)
+{
+	int rc = 0;
+	unsigned char major;
+	unsigned char minor;
+
+	major = ((version >> 8) & 0xFF);
+	minor = (version & 0xFF);
+	if (major != ECRYPTFS_VERSION_MAJOR) {
+		ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
+				"Expected [%d]; got [%d]\n",
+				ECRYPTFS_VERSION_MAJOR, major);
+		rc = -EINVAL;
+		goto out;
+	}
+	if (minor != ECRYPTFS_VERSION_MINOR) {
+		ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
+				"Expected [%d]; got [%d]\n",
+				ECRYPTFS_VERSION_MINOR, minor);
+		rc = -EINVAL;
+		goto out;
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_parse_options
+ * @sb: The ecryptfs super block
+ * @options: The options pased to the kernel
+ *
+ * Parse mount options:
+ * debug=N 	   - ecryptfs_verbosity level for debug output
+ * sig=XXX	   - description(signature) of the key to use
+ *
+ * Returns the dentry object of the lower-level (lower/interposed)
+ * directory; We want to mount our stackable file system on top of
+ * that lower directory.
+ *
+ * The signature of the key to use must be the description of a key
+ * already in the keyring. Mounting will fail if the key can not be
+ * found.
+ *
+ * Returns zero on success; non-zero on error
+ */
+static int ecryptfs_parse_options(struct super_block *sb, char *options)
+{
+	char *p;
+	int rc = 0;
+	int sig_set = 0;
+	int cipher_name_set = 0;
+	int cipher_key_bytes;
+	int cipher_key_bytes_set = 0;
+	struct key *auth_tok_key = NULL;
+	struct ecryptfs_auth_tok *auth_tok = NULL;
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
+	substring_t args[MAX_OPT_ARGS];
+	int token;
+	char *sig_src;
+	char *sig_dst;
+	char *debug_src;
+	char *cipher_name_dst;
+	char *cipher_name_src;
+	char *cipher_key_bytes_src;
+	struct crypto_tfm *tmp_tfm;
+	int cipher_name_len;
+
+	if (!options) {
+		rc = -EINVAL;
+		goto out;
+	}
+	while ((p = strsep(&options, ",")) != NULL) {
+		if (!*p)
+			continue;
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case ecryptfs_opt_sig:
+		case ecryptfs_opt_ecryptfs_sig:
+			sig_src = args[0].from;
+			sig_dst =
+				mount_crypt_stat->global_auth_tok_sig;
+			memcpy(sig_dst, sig_src, ECRYPTFS_SIG_SIZE_HEX);
+			sig_dst[ECRYPTFS_SIG_SIZE_HEX] = '\0';
+			ecryptfs_printk(KERN_DEBUG,
+					"The mount_crypt_stat "
+					"global_auth_tok_sig set to: "
+					"[%s]\n", sig_dst);
+			sig_set = 1;
+			break;
+		case ecryptfs_opt_debug:
+		case ecryptfs_opt_ecryptfs_debug:
+			debug_src = args[0].from;
+			ecryptfs_verbosity =
+				(int)simple_strtol(debug_src, &debug_src,
+						   0);
+			ecryptfs_printk(KERN_DEBUG,
+					"Verbosity set to [%d]" "\n",
+					ecryptfs_verbosity);
+			break;
+		case ecryptfs_opt_cipher:
+		case ecryptfs_opt_ecryptfs_cipher:
+			cipher_name_src = args[0].from;
+			cipher_name_dst =
+				mount_crypt_stat->
+				global_default_cipher_name;
+			strncpy(cipher_name_dst, cipher_name_src,
+				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
+			ecryptfs_printk(KERN_DEBUG,
+					"The mount_crypt_stat "
+					"global_default_cipher_name set to: "
+					"[%s]\n", cipher_name_dst);
+			cipher_name_set = 1;
+			break;
+		case ecryptfs_opt_ecryptfs_key_bytes:
+			cipher_key_bytes_src = args[0].from;
+			cipher_key_bytes =
+				(int)simple_strtol(cipher_key_bytes_src,
+						   &cipher_key_bytes_src, 0);
+			mount_crypt_stat->global_default_cipher_key_size =
+				cipher_key_bytes;
+			ecryptfs_printk(KERN_DEBUG,
+					"The mount_crypt_stat "
+					"global_default_cipher_key_size "
+					"set to: [%d]\n", mount_crypt_stat->
+					global_default_cipher_key_size);
+			cipher_key_bytes_set = 1;
+			break;
+		case ecryptfs_opt_passthrough:
+			mount_crypt_stat->flags |=
+				ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED;
+			break;
+		case ecryptfs_opt_err:
+		default:
+			ecryptfs_printk(KERN_WARNING,
+					"eCryptfs: unrecognized option '%s'\n",
+					p);
+		}
+	}
+	/* Do not support lack of mount-wide signature in 0.1
+	 * release */
+	if (!sig_set) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_ERR, "You must supply a valid "
+				"passphrase auth tok signature as a mount "
+				"parameter; see the eCryptfs README\n");
+		goto out;
+	}
+	if (!cipher_name_set) {
+		cipher_name_len = strlen(ECRYPTFS_DEFAULT_CIPHER);
+		if (unlikely(cipher_name_len
+			     >= ECRYPTFS_MAX_CIPHER_NAME_SIZE)) {
+			rc = -EINVAL;
+			BUG();
+			goto out;
+		}
+		memcpy(mount_crypt_stat->global_default_cipher_name,
+		       ECRYPTFS_DEFAULT_CIPHER, cipher_name_len);
+		mount_crypt_stat->global_default_cipher_name[cipher_name_len]
+		    = '\0';
+	}
+	if (!cipher_key_bytes_set) {
+		mount_crypt_stat->global_default_cipher_key_size =
+			ECRYPTFS_DEFAULT_KEY_BYTES;
+		ecryptfs_printk(KERN_DEBUG, "Cipher key size was not "
+				"specified.  Defaulting to [%d]\n",
+				mount_crypt_stat->
+				global_default_cipher_key_size);
+	}
+	rc = ecryptfs_process_cipher(
+		&tmp_tfm,
+		&mount_crypt_stat->global_key_tfm,
+		mount_crypt_stat->global_default_cipher_name,
+		mount_crypt_stat->global_default_cipher_key_size);
+	if (tmp_tfm)
+		crypto_free_tfm(tmp_tfm);
+	if (rc) {
+		printk(KERN_ERR "Error attempting to initialize cipher [%s] "
+		       "with key size [%Zd] bytes; rc = [%d]\n",
+		       mount_crypt_stat->global_default_cipher_name,
+		       mount_crypt_stat->global_default_cipher_key_size, rc);
+		rc = -EINVAL;
+		goto out;
+	}
+	mutex_init(&mount_crypt_stat->global_key_tfm_mutex);
+	ecryptfs_printk(KERN_DEBUG, "Requesting the key with description: "
+			"[%s]\n", mount_crypt_stat->global_auth_tok_sig);
+	/* The reference to this key is held until umount is done The
+	 * call to key_put is done in ecryptfs_put_super() */
+	auth_tok_key = request_key(&key_type_user,
+				   mount_crypt_stat->global_auth_tok_sig,
+				   NULL);
+	if (!auth_tok_key || IS_ERR(auth_tok_key)) {
+		ecryptfs_printk(KERN_ERR, "Could not find key with "
+				"description: [%s]\n",
+				mount_crypt_stat->global_auth_tok_sig);
+		process_request_key_err(PTR_ERR(auth_tok_key));
+		rc = -EINVAL;
+		goto out;
+	}
+	auth_tok = ecryptfs_get_key_payload_data(auth_tok_key);
+	if (ecryptfs_verify_version(auth_tok->version)) {
+		ecryptfs_printk(KERN_ERR, "Data structure version mismatch. "
+				"Userspace tools must match eCryptfs kernel "
+				"module with major version [%d] and minor "
+				"version [%d]\n", ECRYPTFS_VERSION_MAJOR,
+				ECRYPTFS_VERSION_MINOR);
+		rc = -EINVAL;
+		goto out;
+	}
+	if (auth_tok->token_type != ECRYPTFS_PASSWORD) {
+		ecryptfs_printk(KERN_ERR, "Invalid auth_tok structure "
+				"returned from key\n");
+		rc = -EINVAL;
+		goto out;
+	}
+	mount_crypt_stat->global_auth_tok_key = auth_tok_key;
+	mount_crypt_stat->global_auth_tok = auth_tok;
+out:
+	return rc;
+}
+
+struct kmem_cache *ecryptfs_sb_info_cache;
+
+/**
+ * ecryptfs_fill_super
+ * @sb: The ecryptfs super block
+ * @raw_data: The options passed to mount
+ * @silent: Not used but required by function prototype
+ *
+ * Sets up what we can of the sb, rest is done in ecryptfs_read_super
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int
+ecryptfs_fill_super(struct super_block *sb, void *raw_data, int silent)
+{
+	int rc = 0;
+
+	/* Released in ecryptfs_put_super() */
+	ecryptfs_set_superblock_private(sb,
+					kmem_cache_alloc(ecryptfs_sb_info_cache,
+							 SLAB_KERNEL));
+	if (!ecryptfs_superblock_to_private(sb)) {
+		ecryptfs_printk(KERN_WARNING, "Out of memory\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	memset(ecryptfs_superblock_to_private(sb), 0,
+	       sizeof(struct ecryptfs_sb_info));
+	sb->s_op = &ecryptfs_sops;
+	/* Released through deactivate_super(sb) from get_sb_nodev */
+	sb->s_root = d_alloc(NULL, &(const struct qstr) {
+			     .hash = 0,.name = "/",.len = 1});
+	if (!sb->s_root) {
+		ecryptfs_printk(KERN_ERR, "d_alloc failed\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	sb->s_root->d_op = &ecryptfs_dops;
+	sb->s_root->d_sb = sb;
+	sb->s_root->d_parent = sb->s_root;
+	/* Released in d_release when dput(sb->s_root) is called */
+	/* through deactivate_super(sb) from get_sb_nodev() */
+	ecryptfs_set_dentry_private(sb->s_root,
+				    kmem_cache_alloc(ecryptfs_dentry_info_cache,
+						     SLAB_KERNEL));
+	if (!ecryptfs_dentry_to_private(sb->s_root)) {
+		ecryptfs_printk(KERN_ERR,
+				"dentry_info_cache alloc failed\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	memset(ecryptfs_dentry_to_private(sb->s_root), 0,
+	       sizeof(struct ecryptfs_dentry_info));
+	rc = 0;
+out:
+	/* Should be able to rely on deactivate_super called from
+	 * get_sb_nodev */
+	return rc;
+}
+
+/**
+ * ecryptfs_read_super
+ * @sb: The ecryptfs super block
+ * @dev_name: The path to mount over
+ *
+ * Read the super block of the lower filesystem, and use
+ * ecryptfs_interpose to create our initial inode and super block
+ * struct.
+ */
+static int ecryptfs_read_super(struct super_block *sb, const char *dev_name)
+{
+	int rc;
+	struct nameidata nd;
+	struct dentry *lower_root;
+	struct vfsmount *lower_mnt;
+
+	memset(&nd, 0, sizeof(struct nameidata));
+	rc = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "path_lookup() failed\n");
+		goto out_free;
+	}
+	lower_root = nd.dentry;
+	if (!lower_root->d_inode) {
+		ecryptfs_printk(KERN_WARNING,
+				"No directory to interpose on\n");
+		rc = -ENOENT;
+		goto out_free;
+	}
+	lower_mnt = nd.mnt;
+	ecryptfs_set_superblock_lower(sb, lower_root->d_sb);
+	sb->s_maxbytes = lower_root->d_sb->s_maxbytes;
+	ecryptfs_set_dentry_lower(sb->s_root, lower_root);
+	ecryptfs_set_dentry_lower_mnt(sb->s_root, lower_mnt);
+	if ((rc = ecryptfs_interpose(lower_root, sb->s_root, sb, 0)))
+		goto out_free;
+	rc = 0;
+	goto out;
+out_free:
+	path_release(&nd);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_get_sb
+ * @fs_type
+ * @flags
+ * @dev_name: The path to mount over
+ * @raw_data: The options passed into the kernel
+ *
+ * The whole ecryptfs_get_sb process is broken into 4 functions:
+ * ecryptfs_parse_options(): handle options passed to ecryptfs, if any
+ * ecryptfs_fill_super(): used by get_sb_nodev, fills out the super_block
+ *                        with as much information as it can before needing
+ *                        the lower filesystem.
+ * ecryptfs_read_super(): this accesses the lower filesystem and uses
+ *                        ecryptfs_interpolate to perform most of the linking
+ * ecryptfs_interpolate(): links the lower filesystem into ecryptfs
+ */
+static int ecryptfs_get_sb(struct file_system_type *fs_type, int flags,
+			const char *dev_name, void *raw_data,
+			struct vfsmount *mnt)
+{
+	int rc;
+	struct super_block *sb;
+
+	rc = get_sb_nodev(fs_type, flags, raw_data, ecryptfs_fill_super, mnt);
+	if (rc < 0) {
+		printk(KERN_ERR "Getting sb failed; rc = [%d]\n", rc);
+		goto out;
+	}
+	sb = mnt->mnt_sb;
+	rc = ecryptfs_parse_options(sb, raw_data);
+	if (rc) {
+		printk(KERN_ERR "Error parsing options; rc = [%d]\n", rc);
+		goto out_abort;
+	}
+	rc = ecryptfs_read_super(sb, dev_name);
+	if (rc) {
+		printk(KERN_ERR "Reading sb failed; rc = [%d]\n", rc);
+		goto out_abort;
+	}
+	goto out;
+out_abort:
+	dput(sb->s_root);
+	up_write(&sb->s_umount);
+	deactivate_super(sb);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_kill_block_super
+ * @sb: The ecryptfs super block
+ *
+ * Used to bring the superblock down and free the private data.
+ * Private data is free'd in ecryptfs_put_super()
+ */
+static void ecryptfs_kill_block_super(struct super_block *sb)
+{
+	generic_shutdown_super(sb);
+}
+
+static struct file_system_type ecryptfs_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "ecryptfs",
+	.get_sb = ecryptfs_get_sb,
+	.kill_sb = ecryptfs_kill_block_super,
+	.fs_flags = 0
+};
+
+/**
+ * inode_info_init_once
+ *
+ * Initializes the ecryptfs_inode_info_cache when it is created
+ */
+static void
+inode_info_init_once(void *vptr, struct kmem_cache *cachep, unsigned long flags)
+{
+	struct ecryptfs_inode_info *ei = (struct ecryptfs_inode_info *)vptr;
+
+	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
+	    SLAB_CTOR_CONSTRUCTOR)
+		inode_init_once(&ei->vfs_inode);
+}
+
+static struct ecryptfs_cache_info {
+	kmem_cache_t **cache;
+	const char *name;
+	size_t size;
+	void (*ctor)(void*, struct kmem_cache *, unsigned long);
+} ecryptfs_cache_infos[] = {
+	{
+		.cache = &ecryptfs_auth_tok_list_item_cache,
+		.name = "ecryptfs_auth_tok_list_item",
+		.size = sizeof(struct ecryptfs_auth_tok_list_item),
+	},
+	{
+		.cache = &ecryptfs_file_info_cache,
+		.name = "ecryptfs_file_cache",
+		.size = sizeof(struct ecryptfs_file_info),
+	},
+	{
+		.cache = &ecryptfs_dentry_info_cache,
+		.name = "ecryptfs_dentry_info_cache",
+		.size = sizeof(struct ecryptfs_dentry_info),
+	},
+	{
+		.cache = &ecryptfs_inode_info_cache,
+		.name = "ecryptfs_inode_cache",
+		.size = sizeof(struct ecryptfs_inode_info),
+		.ctor = inode_info_init_once,
+	},
+	{
+		.cache = &ecryptfs_sb_info_cache,
+		.name = "ecryptfs_sb_cache",
+		.size = sizeof(struct ecryptfs_sb_info),
+	},
+	{
+		.cache = &ecryptfs_header_cache_0,
+		.name = "ecryptfs_headers_0",
+		.size = PAGE_CACHE_SIZE,
+	},
+	{
+		.cache = &ecryptfs_header_cache_1,
+		.name = "ecryptfs_headers_1",
+		.size = PAGE_CACHE_SIZE,
+	},
+	{
+		.cache = &ecryptfs_header_cache_2,
+		.name = "ecryptfs_headers_2",
+		.size = PAGE_CACHE_SIZE,
+	},
+	{
+		.cache = &ecryptfs_lower_page_cache,
+		.name = "ecryptfs_lower_page_cache",
+		.size = PAGE_CACHE_SIZE,
+	},
+};
+
+static void ecryptfs_free_kmem_caches(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
+		struct ecryptfs_cache_info *info;
+
+		info = &ecryptfs_cache_infos[i];
+		if (*(info->cache))
+			kmem_cache_destroy(*(info->cache));
+	}
+}
+
+/**
+ * ecryptfs_init_kmem_caches
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_init_kmem_caches(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
+		struct ecryptfs_cache_info *info;
+
+		info = &ecryptfs_cache_infos[i];
+		*(info->cache) = kmem_cache_create(info->name, info->size,
+				0, SLAB_HWCACHE_ALIGN, info->ctor, NULL);
+		if (!*(info->cache)) {
+			ecryptfs_free_kmem_caches();
+			ecryptfs_printk(KERN_WARNING, "%s: "
+					"kmem_cache_create failed\n",
+					info->name);
+			return -ENOMEM;
+		}
+	}
+	return 0;
+}
+
+struct ecryptfs_obj {
+	char *name;
+	struct list_head slot_list;
+	struct kobject kobj;
+};
+
+struct ecryptfs_attribute {
+	struct attribute attr;
+	ssize_t(*show) (struct ecryptfs_obj *, char *);
+	ssize_t(*store) (struct ecryptfs_obj *, const char *, size_t);
+};
+
+static ssize_t
+ecryptfs_attr_store(struct kobject *kobj,
+		    struct attribute *attr, const char *buf, size_t len)
+{
+	struct ecryptfs_obj *obj = container_of(kobj, struct ecryptfs_obj,
+						kobj);
+	struct ecryptfs_attribute *attribute =
+		container_of(attr, struct ecryptfs_attribute, attr);
+
+	return (attribute->store ? attribute->store(obj, buf, len) : 0);
+}
+
+static ssize_t
+ecryptfs_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	struct ecryptfs_obj *obj = container_of(kobj, struct ecryptfs_obj,
+						kobj);
+	struct ecryptfs_attribute *attribute =
+		container_of(attr, struct ecryptfs_attribute, attr);
+
+	return (attribute->show ? attribute->show(obj, buf) : 0);
+}
+
+static struct sysfs_ops ecryptfs_sysfs_ops = {
+	.show = ecryptfs_attr_show,
+	.store = ecryptfs_attr_store
+};
+
+static struct kobj_type ecryptfs_ktype = {
+	.sysfs_ops = &ecryptfs_sysfs_ops
+};
+
+static decl_subsys(ecryptfs, &ecryptfs_ktype, NULL);
+
+static ssize_t version_show(struct ecryptfs_obj *obj, char *buff)
+{
+	return snprintf(buff, PAGE_SIZE, "%d\n", ECRYPTFS_VERSIONING_MASK);
+}
+
+static struct ecryptfs_attribute sysfs_attr_version = __ATTR_RO(version);
+
+struct ecryptfs_version_str_map_elem {
+	u32 flag;
+	char *str;
+} ecryptfs_version_str_map[] = {
+	{ECRYPTFS_VERSIONING_PASSPHRASE, "passphrase"},
+	{ECRYPTFS_VERSIONING_PUBKEY, "pubkey"},
+	{ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH, "plaintext passthrough"},
+	{ECRYPTFS_VERSIONING_POLICY, "policy"}
+};
+
+static ssize_t version_str_show(struct ecryptfs_obj *obj, char *buff)
+{
+	int i;
+	int remaining = PAGE_SIZE;
+	int total_written = 0;
+
+	buff[0] = '\0';
+	for (i = 0; i < ARRAY_SIZE(ecryptfs_version_str_map); i++) {
+		int entry_size;
+
+		if (!(ECRYPTFS_VERSIONING_MASK
+		      & ecryptfs_version_str_map[i].flag))
+			continue;
+		entry_size = strlen(ecryptfs_version_str_map[i].str);
+		if ((entry_size + 2) > remaining)
+			goto out;
+		memcpy(buff, ecryptfs_version_str_map[i].str, entry_size);
+		buff[entry_size++] = '\n';
+		buff[entry_size] = '\0';
+		buff += entry_size;
+		total_written += entry_size;
+		remaining -= entry_size;
+	}
+out:
+	return total_written;
+}
+
+static struct ecryptfs_attribute sysfs_attr_version_str = __ATTR_RO(version_str);
+
+static int do_sysfs_registration(void)
+{
+	int rc;
+
+	if ((rc = subsystem_register(&ecryptfs_subsys))) {
+		printk(KERN_ERR
+		       "Unable to register ecryptfs sysfs subsystem\n");
+		goto out;
+	}
+	rc = sysfs_create_file(&ecryptfs_subsys.kset.kobj,
+			       &sysfs_attr_version.attr);
+	if (rc) {
+		printk(KERN_ERR
+		       "Unable to create ecryptfs version attribute\n");
+		subsystem_unregister(&ecryptfs_subsys);
+		goto out;
+	}
+	rc = sysfs_create_file(&ecryptfs_subsys.kset.kobj,
+			       &sysfs_attr_version_str.attr);
+	if (rc) {
+		printk(KERN_ERR
+		       "Unable to create ecryptfs version_str attribute\n");
+		sysfs_remove_file(&ecryptfs_subsys.kset.kobj,
+				  &sysfs_attr_version.attr);
+		subsystem_unregister(&ecryptfs_subsys);
+		goto out;
+	}
+out:
+	return rc;
+}
+
+static int __init ecryptfs_init(void)
+{
+	int rc;
+
+	if (ECRYPTFS_DEFAULT_EXTENT_SIZE > PAGE_CACHE_SIZE) {
+		rc = -EINVAL;
+		ecryptfs_printk(KERN_ERR, "The eCryptfs extent size is "
+				"larger than the host's page size, and so "
+				"eCryptfs cannot run on this system. The "
+				"default eCryptfs extent size is [%d] bytes; "
+				"the page size is [%d] bytes.\n",
+				ECRYPTFS_DEFAULT_EXTENT_SIZE, PAGE_CACHE_SIZE);
+		goto out;
+	}
+	rc = ecryptfs_init_kmem_caches();
+	if (rc) {
+		printk(KERN_ERR
+		       "Failed to allocate one or more kmem_cache objects\n");
+		goto out;
+	}
+	rc = register_filesystem(&ecryptfs_fs_type);
+	if (rc) {
+		printk(KERN_ERR "Failed to register filesystem\n");
+		ecryptfs_free_kmem_caches();
+		goto out;
+	}
+	kset_set_kset_s(&ecryptfs_subsys, fs_subsys);
+	sysfs_attr_version.attr.owner = THIS_MODULE;
+	sysfs_attr_version_str.attr.owner = THIS_MODULE;
+	rc = do_sysfs_registration();
+	if (rc) {
+		printk(KERN_ERR "sysfs registration failed\n");
+		unregister_filesystem(&ecryptfs_fs_type);
+		ecryptfs_free_kmem_caches();
+		goto out;
+	}
+out:
+	return rc;
+}
+
+static void __exit ecryptfs_exit(void)
+{
+	sysfs_remove_file(&ecryptfs_subsys.kset.kobj,
+			  &sysfs_attr_version.attr);
+	sysfs_remove_file(&ecryptfs_subsys.kset.kobj,
+			  &sysfs_attr_version_str.attr);
+	subsystem_unregister(&ecryptfs_subsys);
+	unregister_filesystem(&ecryptfs_fs_type);
+	ecryptfs_free_kmem_caches();
+}
+
+MODULE_AUTHOR("Michael A. Halcrow <[e-mail]>");
+MODULE_DESCRIPTION("eCryptfs");
+
+MODULE_LICENSE("GPL");
+
+module_init(ecryptfs_init)
+module_exit(ecryptfs_exit)

fs/ecryptfs/mmap.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * This is where eCryptfs coordinates the symmetric encryption and
+ * decryption of the file data as it passes between the lower
+ * encrypted file and the upper decrypted file.
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/page-flags.h>
+#include <linux/mount.h>
+#include <linux/file.h>
+#include <linux/crypto.h>
+#include <linux/scatterlist.h>
+#include "ecryptfs_kernel.h"
+
+struct kmem_cache *ecryptfs_lower_page_cache;
+
+/**
+ * ecryptfs_get1page
+ *
+ * Get one page from cache or lower f/s, return error otherwise.
+ *
+ * Returns unlocked and up-to-date page (if ok), with increased
+ * refcnt.
+ */
+static struct page *ecryptfs_get1page(struct file *file, int index)
+{
+	struct page *page;
+	struct dentry *dentry;
+	struct inode *inode;
+	struct address_space *mapping;
+
+	dentry = file->f_dentry;
+	inode = dentry->d_inode;
+	mapping = inode->i_mapping;
+	page = read_cache_page(mapping, index,
+			       (filler_t *)mapping->a_ops->readpage,
+			       (void *)file);
+	if (IS_ERR(page))
+		goto out;
+	wait_on_page_locked(page);
+out:
+	return page;
+}
+
+static
+int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);
+
+/**
+ * ecryptfs_fill_zeros
+ * @file: The ecryptfs file
+ * @new_length: The new length of the data in the underlying file;
+ *              everything between the prior end of the file and the
+ *              new end of the file will be filled with zero's.
+ *              new_length must be greater than  current length
+ *
+ * Function for handling lseek-ing past the end of the file.
+ *
+ * This function does not support shrinking, only growing a file.
+ *
+ * Returns zero on success; non-zero otherwise.
+ */
+int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
+{
+	int rc = 0;
+	struct dentry *dentry = file->f_dentry;
+	struct inode *inode = dentry->d_inode;
+	pgoff_t old_end_page_index = 0;
+	pgoff_t index = old_end_page_index;
+	int old_end_pos_in_page = -1;
+	pgoff_t new_end_page_index;
+	int new_end_pos_in_page;
+	loff_t cur_length = i_size_read(inode);
+
+	if (cur_length != 0) {
+		index = old_end_page_index =
+		    ((cur_length - 1) >> PAGE_CACHE_SHIFT);
+		old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
+	}
+	new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
+	new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
+	ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
+			"old_end_pos_in_page = [%d]; "
+			"new_end_page_index = [0x%.16x]; "
+			"new_end_pos_in_page = [%d]\n",
+			old_end_page_index, old_end_pos_in_page,
+			new_end_page_index, new_end_pos_in_page);
+	if (old_end_page_index == new_end_page_index) {
+		/* Start and end are in the same page; we just need to
+		 * set a portion of the existing page to zero's */
+		rc = write_zeros(file, index, (old_end_pos_in_page + 1),
+				 (new_end_pos_in_page - old_end_pos_in_page));
+		if (rc)
+			ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
+					"index=[0x%.16x], "
+					"old_end_pos_in_page=[d], "
+					"(PAGE_CACHE_SIZE - new_end_pos_in_page"
+					"=[%d]"
+					")=[d]) returned [%d]\n", file, index,
+					old_end_pos_in_page,
+					new_end_pos_in_page,
+					(PAGE_CACHE_SIZE - new_end_pos_in_page),
+					rc);
+		goto out;
+	}
+	/* Fill the remainder of the previous last page with zeros */
+	rc = write_zeros(file, index, (old_end_pos_in_page + 1),
+			 ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
+				"index=[0x%.16x], old_end_pos_in_page=[d], "
+				"(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
+				"returned [%d]\n", file, index,
+				old_end_pos_in_page,
+				(PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
+		goto out;
+	}
+	index++;
+	while (index < new_end_page_index) {
+		/* Fill all intermediate pages with zeros */
+		rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
+					"index=[0x%.16x], "
+					"old_end_pos_in_page=[d], "
+					"(PAGE_CACHE_SIZE - new_end_pos_in_page"
+					"=[%d]"
+					")=[d]) returned [%d]\n", file, index,
+					old_end_pos_in_page,
+					new_end_pos_in_page,
+					(PAGE_CACHE_SIZE - new_end_pos_in_page),
+					rc);
+			goto out;
+		}
+		index++;
+	}
+	/* Fill the portion at the beginning of the last new page with
+	 * zero's */
+	rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "write_zeros(file="
+				"[%p], index=[0x%.16x], 0, "
+				"new_end_pos_in_page=[%d]"
+				"returned [%d]\n", file, index,
+				new_end_pos_in_page, rc);
+		goto out;
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_writepage
+ * @page: Page that is locked before this call is made
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct ecryptfs_page_crypt_context ctx;
+	int rc;
+
+	ctx.page = page;
+	ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
+	ctx.param.wbc = wbc;
+	rc = ecryptfs_encrypt_page(&ctx);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error encrypting "
+				"page (upper index [0x%.16x])\n", page->index);
+		ClearPageUptodate(page);
+		goto out;
+	}
+	SetPageUptodate(page);
+	unlock_page(page);
+out:
+	return rc;
+}
+
+/**
+ * Reads the data from the lower file file at index lower_page_index
+ * and copies that data into page.
+ *
+ * @param page	Page to fill
+ * @param lower_page_index Index of the page in the lower file to get
+ */
+int ecryptfs_do_readpage(struct file *file, struct page *page,
+			 pgoff_t lower_page_index)
+{
+	int rc;
+	struct dentry *dentry;
+	struct file *lower_file;
+	struct dentry *lower_dentry;
+	struct inode *inode;
+	struct inode *lower_inode;
+	char *page_data;
+	struct page *lower_page = NULL;
+	char *lower_page_data;
+	const struct address_space_operations *lower_a_ops;
+
+	dentry = file->f_dentry;
+	lower_file = ecryptfs_file_to_lower(file);
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	inode = dentry->d_inode;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	lower_a_ops = lower_inode->i_mapping->a_ops;
+	lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
+				     (filler_t *)lower_a_ops->readpage,
+				     (void *)lower_file);
+	if (IS_ERR(lower_page)) {
+		rc = PTR_ERR(lower_page);
+		lower_page = NULL;
+		ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
+		goto out;
+	}
+	wait_on_page_locked(lower_page);
+	page_data = (char *)kmap(page);
+	if (!page_data) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error mapping page\n");
+		goto out;
+	}
+	lower_page_data = (char *)kmap(lower_page);
+	if (!lower_page_data) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error mapping page\n");
+		kunmap(page);
+		goto out;
+	}
+	memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
+	kunmap(lower_page);
+	kunmap(page);
+	rc = 0;
+out:
+	if (likely(lower_page))
+		page_cache_release(lower_page);
+	if (rc == 0)
+		SetPageUptodate(page);
+	else
+		ClearPageUptodate(page);
+	return rc;
+}
+
+/**
+ * ecryptfs_readpage
+ * @file: This is an ecryptfs file
+ * @page: ecryptfs associated page to stick the read data into
+ *
+ * Read in a page, decrypting if necessary.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int ecryptfs_readpage(struct file *file, struct page *page)
+{
+	int rc = 0;
+	struct ecryptfs_crypt_stat *crypt_stat;
+
+	BUG_ON(!(file && file->f_dentry && file->f_dentry->d_inode));
+	crypt_stat =
+		&ecryptfs_inode_to_private(file->f_dentry->d_inode)->crypt_stat;
+	if (!crypt_stat
+	    || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)
+	    || ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
+		ecryptfs_printk(KERN_DEBUG,
+				"Passing through unencrypted page\n");
+		rc = ecryptfs_do_readpage(file, page, page->index);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
+					"[%d]\n", rc);
+			goto out;
+		}
+	} else {
+		rc = ecryptfs_decrypt_page(file, page);
+		if (rc) {
+
+			ecryptfs_printk(KERN_ERR, "Error decrypting page; "
+					"rc = [%d]\n", rc);
+			goto out;
+		}
+	}
+	SetPageUptodate(page);
+out:
+	if (rc)
+		ClearPageUptodate(page);
+	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
+			page->index);
+	unlock_page(page);
+	return rc;
+}
+
+static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
+{
+	struct inode *inode = page->mapping->host;
+	int end_byte_in_page;
+	int rc = 0;
+	char *page_virt;
+
+	if ((i_size_read(inode) / PAGE_CACHE_SIZE) == page->index) {
+		end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
+		if (to > end_byte_in_page)
+			end_byte_in_page = to;
+		page_virt = kmap(page);
+		if (!page_virt) {
+			rc = -ENOMEM;
+			ecryptfs_printk(KERN_WARNING,
+					"Could not map page\n");
+			goto out;
+		}
+		memset((page_virt + end_byte_in_page), 0,
+		       (PAGE_CACHE_SIZE - end_byte_in_page));
+		kunmap(page);
+	}
+out:
+	return rc;
+}
+
+static int ecryptfs_prepare_write(struct file *file, struct page *page,
+				  unsigned from, unsigned to)
+{
+	int rc = 0;
+
+	kmap(page);
+	if (from == 0 && to == PAGE_CACHE_SIZE)
+		goto out;	/* If we are writing a full page, it will be
+				   up to date. */
+	if (!PageUptodate(page))
+		rc = ecryptfs_do_readpage(file, page, page->index);
+out:
+	return rc;
+}
+
+int ecryptfs_grab_and_map_lower_page(struct page **lower_page,
+				     char **lower_virt,
+				     struct inode *lower_inode,
+				     unsigned long lower_page_index)
+{
+	int rc = 0;
+
+	(*lower_page) = grab_cache_page(lower_inode->i_mapping,
+					lower_page_index);
+	if (!(*lower_page)) {
+		ecryptfs_printk(KERN_ERR, "grab_cache_page for "
+				"lower_page_index = [0x%.16x] failed\n",
+				lower_page_index);
+		rc = -EINVAL;
+		goto out;
+	}
+	if (lower_virt)
+		(*lower_virt) = kmap((*lower_page));
+	else
+		kmap((*lower_page));
+out:
+	return rc;
+}
+
+int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
+					      struct inode *lower_inode,
+					      struct writeback_control *wbc)
+{
+	int rc = 0;
+
+	rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
+				"rc = [%d]\n", rc);
+		goto out;
+	}
+	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+	page_cache_release(lower_page);
+out:
+	return rc;
+}
+
+static void ecryptfs_unmap_and_release_lower_page(struct page *lower_page)
+{
+	kunmap(lower_page);
+	ecryptfs_printk(KERN_DEBUG, "Unlocking lower page with index = "
+			"[0x%.16x]\n", lower_page->index);
+	unlock_page(lower_page);
+	page_cache_release(lower_page);
+}
+
+/**
+ * ecryptfs_write_inode_size_to_header
+ *
+ * Writes the lower file size to the first 8 bytes of the header.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+int
+ecryptfs_write_inode_size_to_header(struct file *lower_file,
+				    struct inode *lower_inode,
+				    struct inode *inode)
+{
+	int rc = 0;
+	struct page *header_page;
+	char *header_virt;
+	const struct address_space_operations *lower_a_ops;
+	u64 file_size;
+
+	rc = ecryptfs_grab_and_map_lower_page(&header_page, &header_virt,
+					      lower_inode, 0);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "grab_cache_page for header page "
+				"failed\n");
+		goto out;
+	}
+	lower_a_ops = lower_inode->i_mapping->a_ops;
+	rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
+	file_size = (u64)i_size_read(inode);
+	ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
+	file_size = cpu_to_be64(file_size);
+	memcpy(header_virt, &file_size, sizeof(u64));
+	rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
+	if (rc < 0)
+		ecryptfs_printk(KERN_ERR, "Error commiting header page "
+				"write\n");
+	ecryptfs_unmap_and_release_lower_page(header_page);
+	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+	mark_inode_dirty_sync(inode);
+out:
+	return rc;
+}
+
+int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
+			    struct file *lower_file,
+			    unsigned long lower_page_index, int byte_offset,
+			    int region_bytes)
+{
+	int rc = 0;
+
+	rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, lower_inode,
+					      lower_page_index);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to grab and map "
+				"lower page with index [0x%.16x]\n",
+				lower_page_index);
+		goto out;
+	}
+	rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
+							  (*lower_page),
+							  byte_offset,
+							  region_bytes);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "prepare_write for "
+				"lower_page_index = [0x%.16x] failed; rc = "
+				"[%d]\n", lower_page_index, rc);
+	}
+out:
+	if (rc && (*lower_page)) {
+		ecryptfs_unmap_and_release_lower_page(*lower_page);
+		(*lower_page) = NULL;
+	}
+	return rc;
+}
+
+/**
+ * ecryptfs_commit_lower_page
+ *
+ * Returns zero on success; non-zero on error
+ */
+int
+ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
+			   struct file *lower_file, int byte_offset,
+			   int region_size)
+{
+	int rc = 0;
+
+	rc = lower_inode->i_mapping->a_ops->commit_write(
+		lower_file, lower_page, byte_offset, region_size);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR,
+				"Error committing write; rc = [%d]\n", rc);
+	} else
+		rc = 0;
+	ecryptfs_unmap_and_release_lower_page(lower_page);
+	return rc;
+}
+
+/**
+ * ecryptfs_copy_page_to_lower
+ *
+ * Used for plaintext pass-through; no page index interpolation
+ * required.
+ */
+int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
+				struct file *lower_file)
+{
+	int rc = 0;
+	struct page *lower_page;
+
+	rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
+				     page->index, 0, PAGE_CACHE_SIZE);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to get page "
+				"at index [0x%.16x]\n", page->index);
+		goto out;
+	}
+	/* TODO: aops */
+	memcpy((char *)page_address(lower_page), page_address(page),
+	       PAGE_CACHE_SIZE);
+	rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
+					0, PAGE_CACHE_SIZE);
+	if (rc)
+		ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
+				"at index [0x%.16x]\n", page->index);
+out:
+	return rc;
+}
+
+static int
+process_new_file(struct ecryptfs_crypt_stat *crypt_stat,
+		 struct file *file, struct inode *inode)
+{
+	struct page *header_page;
+	const struct address_space_operations *lower_a_ops;
+	struct inode *lower_inode;
+	struct file *lower_file;
+	char *header_virt;
+	int rc = 0;
+	int current_header_page = 0;
+	int header_pages;
+	int more_header_data_to_be_written = 1;
+
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	lower_file = ecryptfs_file_to_lower(file);
+	lower_a_ops = lower_inode->i_mapping->a_ops;
+	header_pages = ((crypt_stat->header_extent_size
+			 * crypt_stat->num_header_extents_at_front)
+			/ PAGE_CACHE_SIZE);
+	BUG_ON(header_pages < 1);
+	while (current_header_page < header_pages) {
+		rc = ecryptfs_grab_and_map_lower_page(&header_page,
+						      &header_virt,
+						      lower_inode,
+						      current_header_page);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "grab_cache_page for "
+					"header page [%d] failed; rc = [%d]\n",
+					current_header_page, rc);
+			goto out;
+		}
+		rc = lower_a_ops->prepare_write(lower_file, header_page, 0,
+						PAGE_CACHE_SIZE);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error preparing to write "
+					"header page out; rc = [%d]\n", rc);
+			goto out;
+		}
+		memset(header_virt, 0, PAGE_CACHE_SIZE);
+		if (more_header_data_to_be_written) {
+			rc = ecryptfs_write_headers_virt(header_virt,
+							 crypt_stat,
+							 file->f_dentry);
+			if (rc) {
+				ecryptfs_printk(KERN_WARNING, "Error "
+						"generating header; rc = "
+						"[%d]\n", rc);
+				rc = -EIO;
+				memset(header_virt, 0, PAGE_CACHE_SIZE);
+				ecryptfs_unmap_and_release_lower_page(
+					header_page);
+				goto out;
+			}
+			if (current_header_page == 0)
+				memset(header_virt, 0, 8);
+			more_header_data_to_be_written = 0;
+		}
+		rc = lower_a_ops->commit_write(lower_file, header_page, 0,
+					       PAGE_CACHE_SIZE);
+		ecryptfs_unmap_and_release_lower_page(header_page);
+		if (rc < 0) {
+			ecryptfs_printk(KERN_ERR,
+					"Error commiting header page write; "
+					"rc = [%d]\n", rc);
+			break;
+		}
+		current_header_page++;
+	}
+	if (rc >= 0) {
+		rc = 0;
+		ecryptfs_printk(KERN_DEBUG, "lower_inode->i_blocks = "
+				"[0x%.16x]\n", lower_inode->i_blocks);
+		i_size_write(inode, 0);
+		lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+		mark_inode_dirty_sync(inode);
+	}
+	ecryptfs_printk(KERN_DEBUG, "Clearing ECRYPTFS_NEW_FILE flag in "
+			"crypt_stat at memory location [%p]\n", crypt_stat);
+	ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_commit_write
+ * @file: The eCryptfs file object
+ * @page: The eCryptfs page
+ * @from: Ignored (we rotate the page IV on each write)
+ * @to: Ignored
+ *
+ * This is where we encrypt the data and pass the encrypted data to
+ * the lower filesystem.  In OpenPGP-compatible mode, we operate on
+ * entire underlying packets.
+ */
+static int ecryptfs_commit_write(struct file *file, struct page *page,
+				 unsigned from, unsigned to)
+{
+	struct ecryptfs_page_crypt_context ctx;
+	loff_t pos;
+	struct inode *inode;
+	struct inode *lower_inode;
+	struct file *lower_file;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	int rc;
+
+	inode = page->mapping->host;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	lower_file = ecryptfs_file_to_lower(file);
+	mutex_lock(&lower_inode->i_mutex);
+	crypt_stat =
+		&ecryptfs_inode_to_private(file->f_dentry->d_inode)->crypt_stat;
+	if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
+		ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
+			"crypt_stat at memory location [%p]\n", crypt_stat);
+		rc = process_new_file(crypt_stat, file, inode);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error processing new "
+					"file; rc = [%d]\n", rc);
+			goto out;
+		}
+	} else
+		ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
+	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
+			"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
+			to);
+	rc = fill_zeros_to_end_of_page(page, to);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
+				"zeros in page with index = [0x%.16x]\n",
+				page->index);
+		goto out;
+	}
+	ctx.page = page;
+	ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
+	ctx.param.lower_file = lower_file;
+	rc = ecryptfs_encrypt_page(&ctx);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
+				"index [0x%.16x])\n", page->index);
+		goto out;
+	}
+	rc = 0;
+	inode->i_blocks = lower_inode->i_blocks;
+	pos = (page->index << PAGE_CACHE_SHIFT) + to;
+	if (pos > i_size_read(inode)) {
+		i_size_write(inode, pos);
+		ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
+				"[0x%.16x]\n", i_size_read(inode));
+	}
+	ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
+	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+	mark_inode_dirty_sync(inode);
+out:
+	kunmap(page); /* mapped in prior call (prepare_write) */
+	if (rc < 0)
+		ClearPageUptodate(page);
+	else
+		SetPageUptodate(page);
+	mutex_unlock(&lower_inode->i_mutex);
+	return rc;
+}
+
+/**
+ * write_zeros
+ * @file: The ecryptfs file
+ * @index: The index in which we are writing
+ * @start: The position after the last block of data
+ * @num_zeros: The number of zeros to write
+ *
+ * Write a specified number of zero's to a page.
+ *
+ * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
+ */
+static
+int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
+{
+	int rc = 0;
+	struct page *tmp_page;
+
+	tmp_page = ecryptfs_get1page(file, index);
+	if (IS_ERR(tmp_page)) {
+		ecryptfs_printk(KERN_ERR, "Error getting page at index "
+				"[0x%.16x]\n", index);
+		rc = PTR_ERR(tmp_page);
+		goto out;
+	}
+	kmap(tmp_page);
+	rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
+				"to remainder of page at index [0x%.16x]\n",
+				index);
+		kunmap(tmp_page);
+		page_cache_release(tmp_page);
+		goto out;
+	}
+	memset(((char *)page_address(tmp_page) + start), 0, num_zeros);
+	rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
+				"to remainder of page at index [0x%.16x]\n",
+				index);
+		kunmap(tmp_page);
+		page_cache_release(tmp_page);
+		goto out;
+	}
+	rc = 0;
+	kunmap(tmp_page);
+	page_cache_release(tmp_page);
+out:
+	return rc;
+}
+
+static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
+{
+	int rc = 0;
+	struct inode *inode;
+	struct inode *lower_inode;
+
+	inode = (struct inode *)mapping->host;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	if (lower_inode->i_mapping->a_ops->bmap)
+		rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
+							 block);
+	return rc;
+}
+
+static void ecryptfs_sync_page(struct page *page)
+{
+	struct inode *inode;
+	struct inode *lower_inode;
+	struct page *lower_page;
+
+	inode = page->mapping->host;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	/* NOTE: Recently swapped with grab_cache_page(), since
+	 * sync_page() just makes sure that pending I/O gets done. */
+	lower_page = find_lock_page(lower_inode->i_mapping, page->index);
+	if (!lower_page) {
+		ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
+		return;
+	}
+	lower_page->mapping->a_ops->sync_page(lower_page);
+	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
+			lower_page->index);
+	unlock_page(lower_page);
+	page_cache_release(lower_page);
+}
+
+struct address_space_operations ecryptfs_aops = {
+	.writepage = ecryptfs_writepage,
+	.readpage = ecryptfs_readpage,
+	.prepare_write = ecryptfs_prepare_write,
+	.commit_write = ecryptfs_commit_write,
+	.bmap = ecryptfs_bmap,
+	.sync_page = ecryptfs_sync_page,
+};

fs/ecryptfs/super.c

···
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <[e-mail]>
+ *              Michael C. Thompson <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/key.h>
+#include <linux/seq_file.h>
+#include <linux/crypto.h>
+#include "ecryptfs_kernel.h"
+
+struct kmem_cache *ecryptfs_inode_info_cache;
+
+/**
+ * ecryptfs_alloc_inode - allocate an ecryptfs inode
+ * @sb: Pointer to the ecryptfs super block
+ *
+ * Called to bring an inode into existence.
+ *
+ * Only handle allocation, setting up structures should be done in
+ * ecryptfs_read_inode. This is because the kernel, between now and
+ * then, will 0 out the private data pointer.
+ *
+ * Returns a pointer to a newly allocated inode, NULL otherwise
+ */
+static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
+{
+	struct ecryptfs_inode_info *ecryptfs_inode;
+	struct inode *inode = NULL;
+
+	ecryptfs_inode = kmem_cache_alloc(ecryptfs_inode_info_cache,
+					  SLAB_KERNEL);
+	if (unlikely(!ecryptfs_inode))
+		goto out;
+	ecryptfs_init_crypt_stat(&ecryptfs_inode->crypt_stat);
+	inode = &ecryptfs_inode->vfs_inode;
+out:
+	return inode;
+}
+
+/**
+ * ecryptfs_destroy_inode
+ * @inode: The ecryptfs inode
+ *
+ * This is used during the final destruction of the inode.
+ * All allocation of memory related to the inode, including allocated
+ * memory in the crypt_stat struct, will be released here.
+ * There should be no chance that this deallocation will be missed.
+ */
+static void ecryptfs_destroy_inode(struct inode *inode)
+{
+	struct ecryptfs_inode_info *inode_info;
+
+	inode_info = ecryptfs_inode_to_private(inode);
+	ecryptfs_destruct_crypt_stat(&inode_info->crypt_stat);
+	kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
+}
+
+/**
+ * ecryptfs_init_inode
+ * @inode: The ecryptfs inode
+ *
+ * Set up the ecryptfs inode.
+ */
+void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode)
+{
+	ecryptfs_set_inode_lower(inode, lower_inode);
+	inode->i_ino = lower_inode->i_ino;
+	inode->i_version++;
+	inode->i_op = &ecryptfs_main_iops;
+	inode->i_fop = &ecryptfs_main_fops;
+	inode->i_mapping->a_ops = &ecryptfs_aops;
+}
+
+/**
+ * ecryptfs_put_super
+ * @sb: Pointer to the ecryptfs super block
+ *
+ * Final actions when unmounting a file system.
+ * This will handle deallocation and release of our private data.
+ */
+static void ecryptfs_put_super(struct super_block *sb)
+{
+	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
+
+	ecryptfs_destruct_mount_crypt_stat(&sb_info->mount_crypt_stat);
+	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
+	ecryptfs_set_superblock_private(sb, NULL);
+}
+
+/**
+ * ecryptfs_statfs
+ * @sb: The ecryptfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. Currently, we let this pass right through
+ * to the lower filesystem and take no action ourselves.
+ */
+static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf);
+}
+
+/**
+ * ecryptfs_clear_inode
+ * @inode - The ecryptfs inode
+ *
+ * Called by iput() when the inode reference count reached zero
+ * and the inode is not hashed anywhere.  Used to clear anything
+ * that needs to be, before the inode is completely destroyed and put
+ * on the inode free list. We use this to drop out reference to the
+ * lower inode.
+ */
+static void ecryptfs_clear_inode(struct inode *inode)
+{
+	iput(ecryptfs_inode_to_lower(inode));
+}
+
+/**
+ * ecryptfs_umount_begin
+ *
+ * Called in do_umount().
+ */
+static void ecryptfs_umount_begin(struct vfsmount *vfsmnt, int flags)
+{
+	struct vfsmount *lower_mnt =
+		ecryptfs_dentry_to_lower_mnt(vfsmnt->mnt_sb->s_root);
+	struct super_block *lower_sb;
+
+	mntput(lower_mnt);
+	lower_sb = lower_mnt->mnt_sb;
+	if (lower_sb->s_op->umount_begin)
+		lower_sb->s_op->umount_begin(lower_mnt, flags);
+}
+
+/**
+ * ecryptfs_show_options
+ *
+ * Prints the directory we are currently mounted over.
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
+{
+	struct super_block *sb = mnt->mnt_sb;
+	struct dentry *lower_root_dentry = ecryptfs_dentry_to_lower(sb->s_root);
+	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(sb->s_root);
+	char *tmp_page;
+	char *path;
+	int rc = 0;
+
+	tmp_page = (char *)__get_free_page(GFP_KERNEL);
+	if (!tmp_page) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	path = d_path(lower_root_dentry, lower_mnt, tmp_page, PAGE_SIZE);
+	if (IS_ERR(path)) {
+		rc = PTR_ERR(path);
+		goto out;
+	}
+	seq_printf(m, ",dir=%s", path);
+	free_page((unsigned long)tmp_page);
+out:
+	return rc;
+}
+
+struct super_operations ecryptfs_sops = {
+	.alloc_inode = ecryptfs_alloc_inode,
+	.destroy_inode = ecryptfs_destroy_inode,
+	.drop_inode = generic_delete_inode,
+	.put_super = ecryptfs_put_super,
+	.statfs = ecryptfs_statfs,
+	.remount_fs = NULL,
+	.clear_inode = ecryptfs_clear_inode,
+	.umount_begin = ecryptfs_umount_begin,
+	.show_options = ecryptfs_show_options
+};