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1/*
2 * General per-file encryption definition
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_FSCRYPTO_H
11#define _LINUX_FSCRYPTO_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_KEY_DERIVATION_NONCE_SIZE 16
22#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
23
24#define FS_POLICY_FLAGS_PAD_4 0x00
25#define FS_POLICY_FLAGS_PAD_8 0x01
26#define FS_POLICY_FLAGS_PAD_16 0x02
27#define FS_POLICY_FLAGS_PAD_32 0x03
28#define FS_POLICY_FLAGS_PAD_MASK 0x03
29#define FS_POLICY_FLAGS_VALID 0x03
30
31/* Encryption algorithms */
32#define FS_ENCRYPTION_MODE_INVALID 0
33#define FS_ENCRYPTION_MODE_AES_256_XTS 1
34#define FS_ENCRYPTION_MODE_AES_256_GCM 2
35#define FS_ENCRYPTION_MODE_AES_256_CBC 3
36#define FS_ENCRYPTION_MODE_AES_256_CTS 4
37
38/**
39 * Encryption context for inode
40 *
41 * Protector format:
42 * 1 byte: Protector format (1 = this version)
43 * 1 byte: File contents encryption mode
44 * 1 byte: File names encryption mode
45 * 1 byte: Flags
46 * 8 bytes: Master Key descriptor
47 * 16 bytes: Encryption Key derivation nonce
48 */
49struct fscrypt_context {
50 u8 format;
51 u8 contents_encryption_mode;
52 u8 filenames_encryption_mode;
53 u8 flags;
54 u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
55 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
56} __packed;
57
58/* Encryption parameters */
59#define FS_XTS_TWEAK_SIZE 16
60#define FS_AES_128_ECB_KEY_SIZE 16
61#define FS_AES_256_GCM_KEY_SIZE 32
62#define FS_AES_256_CBC_KEY_SIZE 32
63#define FS_AES_256_CTS_KEY_SIZE 32
64#define FS_AES_256_XTS_KEY_SIZE 64
65#define FS_MAX_KEY_SIZE 64
66
67#define FS_KEY_DESC_PREFIX "fscrypt:"
68#define FS_KEY_DESC_PREFIX_SIZE 8
69
70/* This is passed in from userspace into the kernel keyring */
71struct fscrypt_key {
72 u32 mode;
73 u8 raw[FS_MAX_KEY_SIZE];
74 u32 size;
75} __packed;
76
77struct fscrypt_info {
78 u8 ci_data_mode;
79 u8 ci_filename_mode;
80 u8 ci_flags;
81 struct crypto_skcipher *ci_ctfm;
82 struct key *ci_keyring_key;
83 u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
84};
85
86#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
87#define FS_WRITE_PATH_FL 0x00000002
88
89struct fscrypt_ctx {
90 union {
91 struct {
92 struct page *bounce_page; /* Ciphertext page */
93 struct page *control_page; /* Original page */
94 } w;
95 struct {
96 struct bio *bio;
97 struct work_struct work;
98 } r;
99 struct list_head free_list; /* Free list */
100 };
101 u8 flags; /* Flags */
102 u8 mode; /* Encryption mode for tfm */
103};
104
105struct fscrypt_completion_result {
106 struct completion completion;
107 int res;
108};
109
110#define DECLARE_FS_COMPLETION_RESULT(ecr) \
111 struct fscrypt_completion_result ecr = { \
112 COMPLETION_INITIALIZER((ecr).completion), 0 }
113
114static inline int fscrypt_key_size(int mode)
115{
116 switch (mode) {
117 case FS_ENCRYPTION_MODE_AES_256_XTS:
118 return FS_AES_256_XTS_KEY_SIZE;
119 case FS_ENCRYPTION_MODE_AES_256_GCM:
120 return FS_AES_256_GCM_KEY_SIZE;
121 case FS_ENCRYPTION_MODE_AES_256_CBC:
122 return FS_AES_256_CBC_KEY_SIZE;
123 case FS_ENCRYPTION_MODE_AES_256_CTS:
124 return FS_AES_256_CTS_KEY_SIZE;
125 default:
126 BUG();
127 }
128 return 0;
129}
130
131#define FS_FNAME_NUM_SCATTER_ENTRIES 4
132#define FS_CRYPTO_BLOCK_SIZE 16
133#define FS_FNAME_CRYPTO_DIGEST_SIZE 32
134
135/**
136 * For encrypted symlinks, the ciphertext length is stored at the beginning
137 * of the string in little-endian format.
138 */
139struct fscrypt_symlink_data {
140 __le16 len;
141 char encrypted_path[1];
142} __packed;
143
144/**
145 * This function is used to calculate the disk space required to
146 * store a filename of length l in encrypted symlink format.
147 */
148static inline u32 fscrypt_symlink_data_len(u32 l)
149{
150 if (l < FS_CRYPTO_BLOCK_SIZE)
151 l = FS_CRYPTO_BLOCK_SIZE;
152 return (l + sizeof(struct fscrypt_symlink_data) - 1);
153}
154
155struct fscrypt_str {
156 unsigned char *name;
157 u32 len;
158};
159
160struct fscrypt_name {
161 const struct qstr *usr_fname;
162 struct fscrypt_str disk_name;
163 u32 hash;
164 u32 minor_hash;
165 struct fscrypt_str crypto_buf;
166};
167
168#define FSTR_INIT(n, l) { .name = n, .len = l }
169#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
170#define fname_name(p) ((p)->disk_name.name)
171#define fname_len(p) ((p)->disk_name.len)
172
173/*
174 * crypto opertions for filesystems
175 */
176struct fscrypt_operations {
177 int (*get_context)(struct inode *, void *, size_t);
178 int (*key_prefix)(struct inode *, u8 **);
179 int (*prepare_context)(struct inode *);
180 int (*set_context)(struct inode *, const void *, size_t, void *);
181 int (*dummy_context)(struct inode *);
182 bool (*is_encrypted)(struct inode *);
183 bool (*empty_dir)(struct inode *);
184 unsigned (*max_namelen)(struct inode *);
185};
186
187static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
188{
189 if (inode->i_sb->s_cop->dummy_context &&
190 inode->i_sb->s_cop->dummy_context(inode))
191 return true;
192 return false;
193}
194
195static inline bool fscrypt_valid_contents_enc_mode(u32 mode)
196{
197 return (mode == FS_ENCRYPTION_MODE_AES_256_XTS);
198}
199
200static inline bool fscrypt_valid_filenames_enc_mode(u32 mode)
201{
202 return (mode == FS_ENCRYPTION_MODE_AES_256_CTS);
203}
204
205static inline u32 fscrypt_validate_encryption_key_size(u32 mode, u32 size)
206{
207 if (size == fscrypt_key_size(mode))
208 return size;
209 return 0;
210}
211
212static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
213{
214 if (str->len == 1 && str->name[0] == '.')
215 return true;
216
217 if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
218 return true;
219
220 return false;
221}
222
223static inline struct page *fscrypt_control_page(struct page *page)
224{
225#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
226 return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
227#else
228 WARN_ON_ONCE(1);
229 return ERR_PTR(-EINVAL);
230#endif
231}
232
233static inline int fscrypt_has_encryption_key(struct inode *inode)
234{
235#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
236 return (inode->i_crypt_info != NULL);
237#else
238 return 0;
239#endif
240}
241
242static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
243{
244#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
245 spin_lock(&dentry->d_lock);
246 dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
247 spin_unlock(&dentry->d_lock);
248#endif
249}
250
251#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
252extern const struct dentry_operations fscrypt_d_ops;
253#endif
254
255static inline void fscrypt_set_d_op(struct dentry *dentry)
256{
257#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
258 d_set_d_op(dentry, &fscrypt_d_ops);
259#endif
260}
261
262#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
263/* crypto.c */
264extern struct kmem_cache *fscrypt_info_cachep;
265int fscrypt_initialize(void);
266
267extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *, gfp_t);
268extern void fscrypt_release_ctx(struct fscrypt_ctx *);
269extern struct page *fscrypt_encrypt_page(struct inode *, struct page *, gfp_t);
270extern int fscrypt_decrypt_page(struct page *);
271extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
272extern void fscrypt_pullback_bio_page(struct page **, bool);
273extern void fscrypt_restore_control_page(struct page *);
274extern int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t,
275 unsigned int);
276/* policy.c */
277extern int fscrypt_process_policy(struct file *, const struct fscrypt_policy *);
278extern int fscrypt_get_policy(struct inode *, struct fscrypt_policy *);
279extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
280extern int fscrypt_inherit_context(struct inode *, struct inode *,
281 void *, bool);
282/* keyinfo.c */
283extern int get_crypt_info(struct inode *);
284extern int fscrypt_get_encryption_info(struct inode *);
285extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
286
287/* fname.c */
288extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
289 int lookup, struct fscrypt_name *);
290extern void fscrypt_free_filename(struct fscrypt_name *);
291extern u32 fscrypt_fname_encrypted_size(struct inode *, u32);
292extern int fscrypt_fname_alloc_buffer(struct inode *, u32,
293 struct fscrypt_str *);
294extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
295extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
296 const struct fscrypt_str *, struct fscrypt_str *);
297extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
298 struct fscrypt_str *);
299#endif
300
301/* crypto.c */
302static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i,
303 gfp_t f)
304{
305 return ERR_PTR(-EOPNOTSUPP);
306}
307
308static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
309{
310 return;
311}
312
313static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
314 struct page *p, gfp_t f)
315{
316 return ERR_PTR(-EOPNOTSUPP);
317}
318
319static inline int fscrypt_notsupp_decrypt_page(struct page *p)
320{
321 return -EOPNOTSUPP;
322}
323
324static inline void fscrypt_notsupp_decrypt_bio_pages(struct fscrypt_ctx *c,
325 struct bio *b)
326{
327 return;
328}
329
330static inline void fscrypt_notsupp_pullback_bio_page(struct page **p, bool b)
331{
332 return;
333}
334
335static inline void fscrypt_notsupp_restore_control_page(struct page *p)
336{
337 return;
338}
339
340static inline int fscrypt_notsupp_zeroout_range(struct inode *i, pgoff_t p,
341 sector_t s, unsigned int f)
342{
343 return -EOPNOTSUPP;
344}
345
346/* policy.c */
347static inline int fscrypt_notsupp_process_policy(struct file *f,
348 const struct fscrypt_policy *p)
349{
350 return -EOPNOTSUPP;
351}
352
353static inline int fscrypt_notsupp_get_policy(struct inode *i,
354 struct fscrypt_policy *p)
355{
356 return -EOPNOTSUPP;
357}
358
359static inline int fscrypt_notsupp_has_permitted_context(struct inode *p,
360 struct inode *i)
361{
362 return 0;
363}
364
365static inline int fscrypt_notsupp_inherit_context(struct inode *p,
366 struct inode *i, void *v, bool b)
367{
368 return -EOPNOTSUPP;
369}
370
371/* keyinfo.c */
372static inline int fscrypt_notsupp_get_encryption_info(struct inode *i)
373{
374 return -EOPNOTSUPP;
375}
376
377static inline void fscrypt_notsupp_put_encryption_info(struct inode *i,
378 struct fscrypt_info *f)
379{
380 return;
381}
382
383 /* fname.c */
384static inline int fscrypt_notsupp_setup_filename(struct inode *dir,
385 const struct qstr *iname,
386 int lookup, struct fscrypt_name *fname)
387{
388 if (dir->i_sb->s_cop->is_encrypted(dir))
389 return -EOPNOTSUPP;
390
391 memset(fname, 0, sizeof(struct fscrypt_name));
392 fname->usr_fname = iname;
393 fname->disk_name.name = (unsigned char *)iname->name;
394 fname->disk_name.len = iname->len;
395 return 0;
396}
397
398static inline void fscrypt_notsupp_free_filename(struct fscrypt_name *fname)
399{
400 return;
401}
402
403static inline u32 fscrypt_notsupp_fname_encrypted_size(struct inode *i, u32 s)
404{
405 /* never happens */
406 WARN_ON(1);
407 return 0;
408}
409
410static inline int fscrypt_notsupp_fname_alloc_buffer(struct inode *inode,
411 u32 ilen, struct fscrypt_str *crypto_str)
412{
413 return -EOPNOTSUPP;
414}
415
416static inline void fscrypt_notsupp_fname_free_buffer(struct fscrypt_str *c)
417{
418 return;
419}
420
421static inline int fscrypt_notsupp_fname_disk_to_usr(struct inode *inode,
422 u32 hash, u32 minor_hash,
423 const struct fscrypt_str *iname,
424 struct fscrypt_str *oname)
425{
426 return -EOPNOTSUPP;
427}
428
429static inline int fscrypt_notsupp_fname_usr_to_disk(struct inode *inode,
430 const struct qstr *iname,
431 struct fscrypt_str *oname)
432{
433 return -EOPNOTSUPP;
434}
435#endif /* _LINUX_FSCRYPTO_H */