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1/*
2 * fscrypt_common.h: common declarations for per-file encryption
3 *
4 * Copyright (C) 2015, Google, Inc.
5 *
6 * Written by Michael Halcrow, 2015.
7 * Modified by Jaegeuk Kim, 2015.
8 */
9
10#ifndef _LINUX_FSCRYPT_COMMON_H
11#define _LINUX_FSCRYPT_COMMON_H
12
13#include <linux/key.h>
14#include <linux/fs.h>
15#include <linux/mm.h>
16#include <linux/bio.h>
17#include <linux/dcache.h>
18#include <crypto/skcipher.h>
19#include <uapi/linux/fs.h>
20
21#define FS_CRYPTO_BLOCK_SIZE 16
22
23struct fscrypt_info;
24
25struct fscrypt_ctx {
26 union {
27 struct {
28 struct page *bounce_page; /* Ciphertext page */
29 struct page *control_page; /* Original page */
30 } w;
31 struct {
32 struct bio *bio;
33 struct work_struct work;
34 } r;
35 struct list_head free_list; /* Free list */
36 };
37 u8 flags; /* Flags */
38};
39
40/**
41 * For encrypted symlinks, the ciphertext length is stored at the beginning
42 * of the string in little-endian format.
43 */
44struct fscrypt_symlink_data {
45 __le16 len;
46 char encrypted_path[1];
47} __packed;
48
49/**
50 * This function is used to calculate the disk space required to
51 * store a filename of length l in encrypted symlink format.
52 */
53static inline u32 fscrypt_symlink_data_len(u32 l)
54{
55 if (l < FS_CRYPTO_BLOCK_SIZE)
56 l = FS_CRYPTO_BLOCK_SIZE;
57 return (l + sizeof(struct fscrypt_symlink_data) - 1);
58}
59
60struct fscrypt_str {
61 unsigned char *name;
62 u32 len;
63};
64
65struct fscrypt_name {
66 const struct qstr *usr_fname;
67 struct fscrypt_str disk_name;
68 u32 hash;
69 u32 minor_hash;
70 struct fscrypt_str crypto_buf;
71};
72
73#define FSTR_INIT(n, l) { .name = n, .len = l }
74#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
75#define fname_name(p) ((p)->disk_name.name)
76#define fname_len(p) ((p)->disk_name.len)
77
78/*
79 * fscrypt superblock flags
80 */
81#define FS_CFLG_OWN_PAGES (1U << 1)
82
83/*
84 * crypto opertions for filesystems
85 */
86struct fscrypt_operations {
87 unsigned int flags;
88 const char *key_prefix;
89 int (*get_context)(struct inode *, void *, size_t);
90 int (*prepare_context)(struct inode *);
91 int (*set_context)(struct inode *, const void *, size_t, void *);
92 int (*dummy_context)(struct inode *);
93 bool (*is_encrypted)(struct inode *);
94 bool (*empty_dir)(struct inode *);
95 unsigned (*max_namelen)(struct inode *);
96};
97
98static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
99{
100 if (inode->i_sb->s_cop->dummy_context &&
101 inode->i_sb->s_cop->dummy_context(inode))
102 return true;
103 return false;
104}
105
106static inline bool fscrypt_valid_contents_enc_mode(u32 mode)
107{
108 return (mode == FS_ENCRYPTION_MODE_AES_256_XTS);
109}
110
111static inline bool fscrypt_valid_filenames_enc_mode(u32 mode)
112{
113 return (mode == FS_ENCRYPTION_MODE_AES_256_CTS);
114}
115
116static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
117{
118 if (str->len == 1 && str->name[0] == '.')
119 return true;
120
121 if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
122 return true;
123
124 return false;
125}
126
127static inline struct page *fscrypt_control_page(struct page *page)
128{
129#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
130 return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
131#else
132 WARN_ON_ONCE(1);
133 return ERR_PTR(-EINVAL);
134#endif
135}
136
137static inline int fscrypt_has_encryption_key(const struct inode *inode)
138{
139#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
140 return (inode->i_crypt_info != NULL);
141#else
142 return 0;
143#endif
144}
145
146#endif /* _LINUX_FSCRYPT_COMMON_H */