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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
114#define FS_FNAME_NUM_SCATTER_ENTRIES 4
115#define FS_CRYPTO_BLOCK_SIZE 16
116#define FS_FNAME_CRYPTO_DIGEST_SIZE 32
117
118/**
119 * For encrypted symlinks, the ciphertext length is stored at the beginning
120 * of the string in little-endian format.
121 */
122struct fscrypt_symlink_data {
123 __le16 len;
124 char encrypted_path[1];
125} __packed;
126
127/**
128 * This function is used to calculate the disk space required to
129 * store a filename of length l in encrypted symlink format.
130 */
131static inline u32 fscrypt_symlink_data_len(u32 l)
132{
133 if (l < FS_CRYPTO_BLOCK_SIZE)
134 l = FS_CRYPTO_BLOCK_SIZE;
135 return (l + sizeof(struct fscrypt_symlink_data) - 1);
136}
137
138struct fscrypt_str {
139 unsigned char *name;
140 u32 len;
141};
142
143struct fscrypt_name {
144 const struct qstr *usr_fname;
145 struct fscrypt_str disk_name;
146 u32 hash;
147 u32 minor_hash;
148 struct fscrypt_str crypto_buf;
149};
150
151#define FSTR_INIT(n, l) { .name = n, .len = l }
152#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
153#define fname_name(p) ((p)->disk_name.name)
154#define fname_len(p) ((p)->disk_name.len)
155
156/*
157 * crypto opertions for filesystems
158 */
159struct fscrypt_operations {
160 int (*get_context)(struct inode *, void *, size_t);
161 int (*key_prefix)(struct inode *, u8 **);
162 int (*prepare_context)(struct inode *);
163 int (*set_context)(struct inode *, const void *, size_t, void *);
164 int (*dummy_context)(struct inode *);
165 bool (*is_encrypted)(struct inode *);
166 bool (*empty_dir)(struct inode *);
167 unsigned (*max_namelen)(struct inode *);
168};
169
170static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
171{
172 if (inode->i_sb->s_cop->dummy_context &&
173 inode->i_sb->s_cop->dummy_context(inode))
174 return true;
175 return false;
176}
177
178static inline bool fscrypt_valid_contents_enc_mode(u32 mode)
179{
180 return (mode == FS_ENCRYPTION_MODE_AES_256_XTS);
181}
182
183static inline bool fscrypt_valid_filenames_enc_mode(u32 mode)
184{
185 return (mode == FS_ENCRYPTION_MODE_AES_256_CTS);
186}
187
188static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
189{
190 if (str->len == 1 && str->name[0] == '.')
191 return true;
192
193 if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
194 return true;
195
196 return false;
197}
198
199static inline struct page *fscrypt_control_page(struct page *page)
200{
201#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
202 return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
203#else
204 WARN_ON_ONCE(1);
205 return ERR_PTR(-EINVAL);
206#endif
207}
208
209static inline int fscrypt_has_encryption_key(struct inode *inode)
210{
211#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
212 return (inode->i_crypt_info != NULL);
213#else
214 return 0;
215#endif
216}
217
218static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
219{
220#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
221 spin_lock(&dentry->d_lock);
222 dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
223 spin_unlock(&dentry->d_lock);
224#endif
225}
226
227#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
228extern const struct dentry_operations fscrypt_d_ops;
229#endif
230
231static inline void fscrypt_set_d_op(struct dentry *dentry)
232{
233#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
234 d_set_d_op(dentry, &fscrypt_d_ops);
235#endif
236}
237
238#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
239/* crypto.c */
240extern struct kmem_cache *fscrypt_info_cachep;
241int fscrypt_initialize(void);
242
243extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *, gfp_t);
244extern void fscrypt_release_ctx(struct fscrypt_ctx *);
245extern struct page *fscrypt_encrypt_page(struct inode *, struct page *, gfp_t);
246extern int fscrypt_decrypt_page(struct page *);
247extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
248extern void fscrypt_pullback_bio_page(struct page **, bool);
249extern void fscrypt_restore_control_page(struct page *);
250extern int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t,
251 unsigned int);
252/* policy.c */
253extern int fscrypt_process_policy(struct file *, const struct fscrypt_policy *);
254extern int fscrypt_get_policy(struct inode *, struct fscrypt_policy *);
255extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
256extern int fscrypt_inherit_context(struct inode *, struct inode *,
257 void *, bool);
258/* keyinfo.c */
259extern int get_crypt_info(struct inode *);
260extern int fscrypt_get_encryption_info(struct inode *);
261extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
262
263/* fname.c */
264extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
265 int lookup, struct fscrypt_name *);
266extern void fscrypt_free_filename(struct fscrypt_name *);
267extern u32 fscrypt_fname_encrypted_size(struct inode *, u32);
268extern int fscrypt_fname_alloc_buffer(struct inode *, u32,
269 struct fscrypt_str *);
270extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
271extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
272 const struct fscrypt_str *, struct fscrypt_str *);
273extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
274 struct fscrypt_str *);
275#endif
276
277/* crypto.c */
278static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i,
279 gfp_t f)
280{
281 return ERR_PTR(-EOPNOTSUPP);
282}
283
284static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
285{
286 return;
287}
288
289static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
290 struct page *p, gfp_t f)
291{
292 return ERR_PTR(-EOPNOTSUPP);
293}
294
295static inline int fscrypt_notsupp_decrypt_page(struct page *p)
296{
297 return -EOPNOTSUPP;
298}
299
300static inline void fscrypt_notsupp_decrypt_bio_pages(struct fscrypt_ctx *c,
301 struct bio *b)
302{
303 return;
304}
305
306static inline void fscrypt_notsupp_pullback_bio_page(struct page **p, bool b)
307{
308 return;
309}
310
311static inline void fscrypt_notsupp_restore_control_page(struct page *p)
312{
313 return;
314}
315
316static inline int fscrypt_notsupp_zeroout_range(struct inode *i, pgoff_t p,
317 sector_t s, unsigned int f)
318{
319 return -EOPNOTSUPP;
320}
321
322/* policy.c */
323static inline int fscrypt_notsupp_process_policy(struct file *f,
324 const struct fscrypt_policy *p)
325{
326 return -EOPNOTSUPP;
327}
328
329static inline int fscrypt_notsupp_get_policy(struct inode *i,
330 struct fscrypt_policy *p)
331{
332 return -EOPNOTSUPP;
333}
334
335static inline int fscrypt_notsupp_has_permitted_context(struct inode *p,
336 struct inode *i)
337{
338 return 0;
339}
340
341static inline int fscrypt_notsupp_inherit_context(struct inode *p,
342 struct inode *i, void *v, bool b)
343{
344 return -EOPNOTSUPP;
345}
346
347/* keyinfo.c */
348static inline int fscrypt_notsupp_get_encryption_info(struct inode *i)
349{
350 return -EOPNOTSUPP;
351}
352
353static inline void fscrypt_notsupp_put_encryption_info(struct inode *i,
354 struct fscrypt_info *f)
355{
356 return;
357}
358
359 /* fname.c */
360static inline int fscrypt_notsupp_setup_filename(struct inode *dir,
361 const struct qstr *iname,
362 int lookup, struct fscrypt_name *fname)
363{
364 if (dir->i_sb->s_cop->is_encrypted(dir))
365 return -EOPNOTSUPP;
366
367 memset(fname, 0, sizeof(struct fscrypt_name));
368 fname->usr_fname = iname;
369 fname->disk_name.name = (unsigned char *)iname->name;
370 fname->disk_name.len = iname->len;
371 return 0;
372}
373
374static inline void fscrypt_notsupp_free_filename(struct fscrypt_name *fname)
375{
376 return;
377}
378
379static inline u32 fscrypt_notsupp_fname_encrypted_size(struct inode *i, u32 s)
380{
381 /* never happens */
382 WARN_ON(1);
383 return 0;
384}
385
386static inline int fscrypt_notsupp_fname_alloc_buffer(struct inode *inode,
387 u32 ilen, struct fscrypt_str *crypto_str)
388{
389 return -EOPNOTSUPP;
390}
391
392static inline void fscrypt_notsupp_fname_free_buffer(struct fscrypt_str *c)
393{
394 return;
395}
396
397static inline int fscrypt_notsupp_fname_disk_to_usr(struct inode *inode,
398 u32 hash, u32 minor_hash,
399 const struct fscrypt_str *iname,
400 struct fscrypt_str *oname)
401{
402 return -EOPNOTSUPP;
403}
404
405static inline int fscrypt_notsupp_fname_usr_to_disk(struct inode *inode,
406 const struct qstr *iname,
407 struct fscrypt_str *oname)
408{
409 return -EOPNOTSUPP;
410}
411#endif /* _LINUX_FSCRYPTO_H */