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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * fscrypt_private.h
4 *
5 * Copyright (C) 2015, Google, Inc.
6 *
7 * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
8 * Heavily modified since then.
9 */
10
11#ifndef _FSCRYPT_PRIVATE_H
12#define _FSCRYPT_PRIVATE_H
13
14#include <linux/fscrypt.h>
15#include <crypto/hash.h>
16
17#define CONST_STRLEN(str) (sizeof(str) - 1)
18
19#define FS_KEY_DERIVATION_NONCE_SIZE 16
20
21#define FSCRYPT_MIN_KEY_SIZE 16
22
23#define FSCRYPT_CONTEXT_V1 1
24#define FSCRYPT_CONTEXT_V2 2
25
26struct fscrypt_context_v1 {
27 u8 version; /* FSCRYPT_CONTEXT_V1 */
28 u8 contents_encryption_mode;
29 u8 filenames_encryption_mode;
30 u8 flags;
31 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
32 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
33};
34
35struct fscrypt_context_v2 {
36 u8 version; /* FSCRYPT_CONTEXT_V2 */
37 u8 contents_encryption_mode;
38 u8 filenames_encryption_mode;
39 u8 flags;
40 u8 __reserved[4];
41 u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
42 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
43};
44
45/**
46 * fscrypt_context - the encryption context of an inode
47 *
48 * This is the on-disk equivalent of an fscrypt_policy, stored alongside each
49 * encrypted file usually in a hidden extended attribute. It contains the
50 * fields from the fscrypt_policy, in order to identify the encryption algorithm
51 * and key with which the file is encrypted. It also contains a nonce that was
52 * randomly generated by fscrypt itself; this is used as KDF input or as a tweak
53 * to cause different files to be encrypted differently.
54 */
55union fscrypt_context {
56 u8 version;
57 struct fscrypt_context_v1 v1;
58 struct fscrypt_context_v2 v2;
59};
60
61/*
62 * Return the size expected for the given fscrypt_context based on its version
63 * number, or 0 if the context version is unrecognized.
64 */
65static inline int fscrypt_context_size(const union fscrypt_context *ctx)
66{
67 switch (ctx->version) {
68 case FSCRYPT_CONTEXT_V1:
69 BUILD_BUG_ON(sizeof(ctx->v1) != 28);
70 return sizeof(ctx->v1);
71 case FSCRYPT_CONTEXT_V2:
72 BUILD_BUG_ON(sizeof(ctx->v2) != 40);
73 return sizeof(ctx->v2);
74 }
75 return 0;
76}
77
78#undef fscrypt_policy
79union fscrypt_policy {
80 u8 version;
81 struct fscrypt_policy_v1 v1;
82 struct fscrypt_policy_v2 v2;
83};
84
85/*
86 * Return the size expected for the given fscrypt_policy based on its version
87 * number, or 0 if the policy version is unrecognized.
88 */
89static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
90{
91 switch (policy->version) {
92 case FSCRYPT_POLICY_V1:
93 return sizeof(policy->v1);
94 case FSCRYPT_POLICY_V2:
95 return sizeof(policy->v2);
96 }
97 return 0;
98}
99
100/* Return the contents encryption mode of a valid encryption policy */
101static inline u8
102fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
103{
104 switch (policy->version) {
105 case FSCRYPT_POLICY_V1:
106 return policy->v1.contents_encryption_mode;
107 case FSCRYPT_POLICY_V2:
108 return policy->v2.contents_encryption_mode;
109 }
110 BUG();
111}
112
113/* Return the filenames encryption mode of a valid encryption policy */
114static inline u8
115fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
116{
117 switch (policy->version) {
118 case FSCRYPT_POLICY_V1:
119 return policy->v1.filenames_encryption_mode;
120 case FSCRYPT_POLICY_V2:
121 return policy->v2.filenames_encryption_mode;
122 }
123 BUG();
124}
125
126/* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */
127static inline u8
128fscrypt_policy_flags(const union fscrypt_policy *policy)
129{
130 switch (policy->version) {
131 case FSCRYPT_POLICY_V1:
132 return policy->v1.flags;
133 case FSCRYPT_POLICY_V2:
134 return policy->v2.flags;
135 }
136 BUG();
137}
138
139static inline bool
140fscrypt_is_direct_key_policy(const union fscrypt_policy *policy)
141{
142 return fscrypt_policy_flags(policy) & FSCRYPT_POLICY_FLAG_DIRECT_KEY;
143}
144
145/**
146 * For encrypted symlinks, the ciphertext length is stored at the beginning
147 * of the string in little-endian format.
148 */
149struct fscrypt_symlink_data {
150 __le16 len;
151 char encrypted_path[1];
152} __packed;
153
154/*
155 * fscrypt_info - the "encryption key" for an inode
156 *
157 * When an encrypted file's key is made available, an instance of this struct is
158 * allocated and stored in ->i_crypt_info. Once created, it remains until the
159 * inode is evicted.
160 */
161struct fscrypt_info {
162
163 /* The actual crypto transform used for encryption and decryption */
164 struct crypto_skcipher *ci_ctfm;
165
166 /*
167 * Cipher for ESSIV IV generation. Only set for CBC contents
168 * encryption, otherwise is NULL.
169 */
170 struct crypto_cipher *ci_essiv_tfm;
171
172 /*
173 * Encryption mode used for this inode. It corresponds to either the
174 * contents or filenames encryption mode, depending on the inode type.
175 */
176 struct fscrypt_mode *ci_mode;
177
178 /* Back-pointer to the inode */
179 struct inode *ci_inode;
180
181 /*
182 * The master key with which this inode was unlocked (decrypted). This
183 * will be NULL if the master key was found in a process-subscribed
184 * keyring rather than in the filesystem-level keyring.
185 */
186 struct key *ci_master_key;
187
188 /*
189 * Link in list of inodes that were unlocked with the master key.
190 * Only used when ->ci_master_key is set.
191 */
192 struct list_head ci_master_key_link;
193
194 /*
195 * If non-NULL, then encryption is done using the master key directly
196 * and ci_ctfm will equal ci_direct_key->dk_ctfm.
197 */
198 struct fscrypt_direct_key *ci_direct_key;
199
200 /* The encryption policy used by this inode */
201 union fscrypt_policy ci_policy;
202
203 /* This inode's nonce, copied from the fscrypt_context */
204 u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
205};
206
207typedef enum {
208 FS_DECRYPT = 0,
209 FS_ENCRYPT,
210} fscrypt_direction_t;
211
212#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
213
214static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
215 u32 filenames_mode)
216{
217 if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
218 filenames_mode == FSCRYPT_MODE_AES_128_CTS)
219 return true;
220
221 if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
222 filenames_mode == FSCRYPT_MODE_AES_256_CTS)
223 return true;
224
225 if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
226 filenames_mode == FSCRYPT_MODE_ADIANTUM)
227 return true;
228
229 return false;
230}
231
232/* crypto.c */
233extern struct kmem_cache *fscrypt_info_cachep;
234extern int fscrypt_initialize(unsigned int cop_flags);
235extern int fscrypt_crypt_block(const struct inode *inode,
236 fscrypt_direction_t rw, u64 lblk_num,
237 struct page *src_page, struct page *dest_page,
238 unsigned int len, unsigned int offs,
239 gfp_t gfp_flags);
240extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
241extern const struct dentry_operations fscrypt_d_ops;
242
243extern void __printf(3, 4) __cold
244fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
245
246#define fscrypt_warn(inode, fmt, ...) \
247 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
248#define fscrypt_err(inode, fmt, ...) \
249 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
250
251#define FSCRYPT_MAX_IV_SIZE 32
252
253union fscrypt_iv {
254 struct {
255 /* logical block number within the file */
256 __le64 lblk_num;
257
258 /* per-file nonce; only set in DIRECT_KEY mode */
259 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
260 };
261 u8 raw[FSCRYPT_MAX_IV_SIZE];
262};
263
264void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
265 const struct fscrypt_info *ci);
266
267/* fname.c */
268extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
269 u8 *out, unsigned int olen);
270extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
271 u32 orig_len, u32 max_len,
272 u32 *encrypted_len_ret);
273
274/* hkdf.c */
275
276struct fscrypt_hkdf {
277 struct crypto_shash *hmac_tfm;
278};
279
280extern int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
281 unsigned int master_key_size);
282
283/*
284 * The list of contexts in which fscrypt uses HKDF. These values are used as
285 * the first byte of the HKDF application-specific info string to guarantee that
286 * info strings are never repeated between contexts. This ensures that all HKDF
287 * outputs are unique and cryptographically isolated, i.e. knowledge of one
288 * output doesn't reveal another.
289 */
290#define HKDF_CONTEXT_KEY_IDENTIFIER 1
291#define HKDF_CONTEXT_PER_FILE_KEY 2
292#define HKDF_CONTEXT_PER_MODE_KEY 3
293
294extern int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context,
295 const u8 *info, unsigned int infolen,
296 u8 *okm, unsigned int okmlen);
297
298extern void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
299
300/* keyring.c */
301
302/*
303 * fscrypt_master_key_secret - secret key material of an in-use master key
304 */
305struct fscrypt_master_key_secret {
306
307 /*
308 * For v2 policy keys: HKDF context keyed by this master key.
309 * For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
310 */
311 struct fscrypt_hkdf hkdf;
312
313 /* Size of the raw key in bytes. Set even if ->raw isn't set. */
314 u32 size;
315
316 /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
317 u8 raw[FSCRYPT_MAX_KEY_SIZE];
318
319} __randomize_layout;
320
321/*
322 * fscrypt_master_key - an in-use master key
323 *
324 * This represents a master encryption key which has been added to the
325 * filesystem and can be used to "unlock" the encrypted files which were
326 * encrypted with it.
327 */
328struct fscrypt_master_key {
329
330 /*
331 * The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
332 * executed, this is wiped and no new inodes can be unlocked with this
333 * key; however, there may still be inodes in ->mk_decrypted_inodes
334 * which could not be evicted. As long as some inodes still remain,
335 * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
336 * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
337 *
338 * Locking: protected by key->sem (outer) and mk_secret_sem (inner).
339 * The reason for two locks is that key->sem also protects modifying
340 * mk_users, which ranks it above the semaphore for the keyring key
341 * type, which is in turn above page faults (via keyring_read). But
342 * sometimes filesystems call fscrypt_get_encryption_info() from within
343 * a transaction, which ranks it below page faults. So we need a
344 * separate lock which protects mk_secret but not also mk_users.
345 */
346 struct fscrypt_master_key_secret mk_secret;
347 struct rw_semaphore mk_secret_sem;
348
349 /*
350 * For v1 policy keys: an arbitrary key descriptor which was assigned by
351 * userspace (->descriptor).
352 *
353 * For v2 policy keys: a cryptographic hash of this key (->identifier).
354 */
355 struct fscrypt_key_specifier mk_spec;
356
357 /*
358 * Keyring which contains a key of type 'key_type_fscrypt_user' for each
359 * user who has added this key. Normally each key will be added by just
360 * one user, but it's possible that multiple users share a key, and in
361 * that case we need to keep track of those users so that one user can't
362 * remove the key before the others want it removed too.
363 *
364 * This is NULL for v1 policy keys; those can only be added by root.
365 *
366 * Locking: in addition to this keyrings own semaphore, this is
367 * protected by the master key's key->sem, so we can do atomic
368 * search+insert. It can also be searched without taking any locks, but
369 * in that case the returned key may have already been removed.
370 */
371 struct key *mk_users;
372
373 /*
374 * Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
375 * Once this goes to 0, the master key is removed from ->s_master_keys.
376 * The 'struct fscrypt_master_key' will continue to live as long as the
377 * 'struct key' whose payload it is, but we won't let this reference
378 * count rise again.
379 */
380 refcount_t mk_refcount;
381
382 /*
383 * List of inodes that were unlocked using this key. This allows the
384 * inodes to be evicted efficiently if the key is removed.
385 */
386 struct list_head mk_decrypted_inodes;
387 spinlock_t mk_decrypted_inodes_lock;
388
389 /* Per-mode tfms for DIRECT_KEY policies, allocated on-demand */
390 struct crypto_skcipher *mk_mode_keys[__FSCRYPT_MODE_MAX + 1];
391
392} __randomize_layout;
393
394static inline bool
395is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
396{
397 /*
398 * The READ_ONCE() is only necessary for fscrypt_drop_inode() and
399 * fscrypt_key_describe(). These run in atomic context, so they can't
400 * take ->mk_secret_sem and thus 'secret' can change concurrently which
401 * would be a data race. But they only need to know whether the secret
402 * *was* present at the time of check, so READ_ONCE() suffices.
403 */
404 return READ_ONCE(secret->size) != 0;
405}
406
407static inline const char *master_key_spec_type(
408 const struct fscrypt_key_specifier *spec)
409{
410 switch (spec->type) {
411 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
412 return "descriptor";
413 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
414 return "identifier";
415 }
416 return "[unknown]";
417}
418
419static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
420{
421 switch (spec->type) {
422 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
423 return FSCRYPT_KEY_DESCRIPTOR_SIZE;
424 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
425 return FSCRYPT_KEY_IDENTIFIER_SIZE;
426 }
427 return 0;
428}
429
430extern struct key *
431fscrypt_find_master_key(struct super_block *sb,
432 const struct fscrypt_key_specifier *mk_spec);
433
434extern int fscrypt_verify_key_added(struct super_block *sb,
435 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
436
437extern int __init fscrypt_init_keyring(void);
438
439/* keysetup.c */
440
441struct fscrypt_mode {
442 const char *friendly_name;
443 const char *cipher_str;
444 int keysize;
445 int ivsize;
446 bool logged_impl_name;
447 bool needs_essiv;
448};
449
450static inline bool
451fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
452{
453 return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
454}
455
456extern struct crypto_skcipher *
457fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
458 const struct inode *inode);
459
460extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
461 const u8 *derived_key);
462
463/* keysetup_v1.c */
464
465extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
466
467extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
468 const u8 *raw_master_key);
469
470extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
471 struct fscrypt_info *ci);
472/* policy.c */
473
474extern bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
475 const union fscrypt_policy *policy2);
476extern bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
477 const struct inode *inode);
478extern int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
479 const union fscrypt_context *ctx_u,
480 int ctx_size);
481
482#endif /* _FSCRYPT_PRIVATE_H */
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * fscrypt_private.h
4 *
5 * Copyright (C) 2015, Google, Inc.
6 *
7 * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
8 * Heavily modified since then.
9 */
10
11#ifndef _FSCRYPT_PRIVATE_H
12#define _FSCRYPT_PRIVATE_H
13
14#include <linux/fscrypt.h>
15#include <linux/siphash.h>
16#include <crypto/hash.h>
17#include <linux/blk-crypto.h>
18
19#define CONST_STRLEN(str) (sizeof(str) - 1)
20
21#define FSCRYPT_FILE_NONCE_SIZE 16
22
23#define FSCRYPT_MIN_KEY_SIZE 16
24
25#define FSCRYPT_CONTEXT_V1 1
26#define FSCRYPT_CONTEXT_V2 2
27
28struct fscrypt_context_v1 {
29 u8 version; /* FSCRYPT_CONTEXT_V1 */
30 u8 contents_encryption_mode;
31 u8 filenames_encryption_mode;
32 u8 flags;
33 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
34 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
35};
36
37struct fscrypt_context_v2 {
38 u8 version; /* FSCRYPT_CONTEXT_V2 */
39 u8 contents_encryption_mode;
40 u8 filenames_encryption_mode;
41 u8 flags;
42 u8 __reserved[4];
43 u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
44 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
45};
46
47/*
48 * fscrypt_context - the encryption context of an inode
49 *
50 * This is the on-disk equivalent of an fscrypt_policy, stored alongside each
51 * encrypted file usually in a hidden extended attribute. It contains the
52 * fields from the fscrypt_policy, in order to identify the encryption algorithm
53 * and key with which the file is encrypted. It also contains a nonce that was
54 * randomly generated by fscrypt itself; this is used as KDF input or as a tweak
55 * to cause different files to be encrypted differently.
56 */
57union fscrypt_context {
58 u8 version;
59 struct fscrypt_context_v1 v1;
60 struct fscrypt_context_v2 v2;
61};
62
63/*
64 * Return the size expected for the given fscrypt_context based on its version
65 * number, or 0 if the context version is unrecognized.
66 */
67static inline int fscrypt_context_size(const union fscrypt_context *ctx)
68{
69 switch (ctx->version) {
70 case FSCRYPT_CONTEXT_V1:
71 BUILD_BUG_ON(sizeof(ctx->v1) != 28);
72 return sizeof(ctx->v1);
73 case FSCRYPT_CONTEXT_V2:
74 BUILD_BUG_ON(sizeof(ctx->v2) != 40);
75 return sizeof(ctx->v2);
76 }
77 return 0;
78}
79
80/* Check whether an fscrypt_context has a recognized version number and size */
81static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx,
82 int ctx_size)
83{
84 return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx);
85}
86
87/* Retrieve the context's nonce, assuming the context was already validated */
88static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx)
89{
90 switch (ctx->version) {
91 case FSCRYPT_CONTEXT_V1:
92 return ctx->v1.nonce;
93 case FSCRYPT_CONTEXT_V2:
94 return ctx->v2.nonce;
95 }
96 WARN_ON(1);
97 return NULL;
98}
99
100#undef fscrypt_policy
101union fscrypt_policy {
102 u8 version;
103 struct fscrypt_policy_v1 v1;
104 struct fscrypt_policy_v2 v2;
105};
106
107/*
108 * Return the size expected for the given fscrypt_policy based on its version
109 * number, or 0 if the policy version is unrecognized.
110 */
111static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
112{
113 switch (policy->version) {
114 case FSCRYPT_POLICY_V1:
115 return sizeof(policy->v1);
116 case FSCRYPT_POLICY_V2:
117 return sizeof(policy->v2);
118 }
119 return 0;
120}
121
122/* Return the contents encryption mode of a valid encryption policy */
123static inline u8
124fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
125{
126 switch (policy->version) {
127 case FSCRYPT_POLICY_V1:
128 return policy->v1.contents_encryption_mode;
129 case FSCRYPT_POLICY_V2:
130 return policy->v2.contents_encryption_mode;
131 }
132 BUG();
133}
134
135/* Return the filenames encryption mode of a valid encryption policy */
136static inline u8
137fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
138{
139 switch (policy->version) {
140 case FSCRYPT_POLICY_V1:
141 return policy->v1.filenames_encryption_mode;
142 case FSCRYPT_POLICY_V2:
143 return policy->v2.filenames_encryption_mode;
144 }
145 BUG();
146}
147
148/* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */
149static inline u8
150fscrypt_policy_flags(const union fscrypt_policy *policy)
151{
152 switch (policy->version) {
153 case FSCRYPT_POLICY_V1:
154 return policy->v1.flags;
155 case FSCRYPT_POLICY_V2:
156 return policy->v2.flags;
157 }
158 BUG();
159}
160
161/*
162 * For encrypted symlinks, the ciphertext length is stored at the beginning
163 * of the string in little-endian format.
164 */
165struct fscrypt_symlink_data {
166 __le16 len;
167 char encrypted_path[1];
168} __packed;
169
170/**
171 * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption
172 * @tfm: crypto API transform object
173 * @blk_key: key for blk-crypto
174 *
175 * Normally only one of the fields will be non-NULL.
176 */
177struct fscrypt_prepared_key {
178 struct crypto_skcipher *tfm;
179#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
180 struct fscrypt_blk_crypto_key *blk_key;
181#endif
182};
183
184/*
185 * fscrypt_info - the "encryption key" for an inode
186 *
187 * When an encrypted file's key is made available, an instance of this struct is
188 * allocated and stored in ->i_crypt_info. Once created, it remains until the
189 * inode is evicted.
190 */
191struct fscrypt_info {
192
193 /* The key in a form prepared for actual encryption/decryption */
194 struct fscrypt_prepared_key ci_enc_key;
195
196 /* True if ci_enc_key should be freed when this fscrypt_info is freed */
197 bool ci_owns_key;
198
199#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
200 /*
201 * True if this inode will use inline encryption (blk-crypto) instead of
202 * the traditional filesystem-layer encryption.
203 */
204 bool ci_inlinecrypt;
205#endif
206
207 /*
208 * Encryption mode used for this inode. It corresponds to either the
209 * contents or filenames encryption mode, depending on the inode type.
210 */
211 struct fscrypt_mode *ci_mode;
212
213 /* Back-pointer to the inode */
214 struct inode *ci_inode;
215
216 /*
217 * The master key with which this inode was unlocked (decrypted). This
218 * will be NULL if the master key was found in a process-subscribed
219 * keyring rather than in the filesystem-level keyring.
220 */
221 struct key *ci_master_key;
222
223 /*
224 * Link in list of inodes that were unlocked with the master key.
225 * Only used when ->ci_master_key is set.
226 */
227 struct list_head ci_master_key_link;
228
229 /*
230 * If non-NULL, then encryption is done using the master key directly
231 * and ci_enc_key will equal ci_direct_key->dk_key.
232 */
233 struct fscrypt_direct_key *ci_direct_key;
234
235 /*
236 * This inode's hash key for filenames. This is a 128-bit SipHash-2-4
237 * key. This is only set for directories that use a keyed dirhash over
238 * the plaintext filenames -- currently just casefolded directories.
239 */
240 siphash_key_t ci_dirhash_key;
241 bool ci_dirhash_key_initialized;
242
243 /* The encryption policy used by this inode */
244 union fscrypt_policy ci_policy;
245
246 /* This inode's nonce, copied from the fscrypt_context */
247 u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
248
249 /* Hashed inode number. Only set for IV_INO_LBLK_32 */
250 u32 ci_hashed_ino;
251};
252
253typedef enum {
254 FS_DECRYPT = 0,
255 FS_ENCRYPT,
256} fscrypt_direction_t;
257
258/* crypto.c */
259extern struct kmem_cache *fscrypt_info_cachep;
260int fscrypt_initialize(unsigned int cop_flags);
261int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
262 u64 lblk_num, struct page *src_page,
263 struct page *dest_page, unsigned int len,
264 unsigned int offs, gfp_t gfp_flags);
265struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
266
267void __printf(3, 4) __cold
268fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
269
270#define fscrypt_warn(inode, fmt, ...) \
271 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
272#define fscrypt_err(inode, fmt, ...) \
273 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
274
275#define FSCRYPT_MAX_IV_SIZE 32
276
277union fscrypt_iv {
278 struct {
279 /* logical block number within the file */
280 __le64 lblk_num;
281
282 /* per-file nonce; only set in DIRECT_KEY mode */
283 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
284 };
285 u8 raw[FSCRYPT_MAX_IV_SIZE];
286 __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)];
287};
288
289void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
290 const struct fscrypt_info *ci);
291
292/* fname.c */
293int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
294 u8 *out, unsigned int olen);
295bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
296 u32 max_len, u32 *encrypted_len_ret);
297extern const struct dentry_operations fscrypt_d_ops;
298
299/* hkdf.c */
300
301struct fscrypt_hkdf {
302 struct crypto_shash *hmac_tfm;
303};
304
305int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
306 unsigned int master_key_size);
307
308/*
309 * The list of contexts in which fscrypt uses HKDF. These values are used as
310 * the first byte of the HKDF application-specific info string to guarantee that
311 * info strings are never repeated between contexts. This ensures that all HKDF
312 * outputs are unique and cryptographically isolated, i.e. knowledge of one
313 * output doesn't reveal another.
314 */
315#define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */
316#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */
317#define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */
318#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */
319#define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */
320#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */
321#define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */
322
323int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
324 const u8 *info, unsigned int infolen,
325 u8 *okm, unsigned int okmlen);
326
327void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
328
329/* inline_crypt.c */
330#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
331int fscrypt_select_encryption_impl(struct fscrypt_info *ci);
332
333static inline bool
334fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
335{
336 return ci->ci_inlinecrypt;
337}
338
339int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
340 const u8 *raw_key,
341 const struct fscrypt_info *ci);
342
343void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key);
344
345/*
346 * Check whether the crypto transform or blk-crypto key has been allocated in
347 * @prep_key, depending on which encryption implementation the file will use.
348 */
349static inline bool
350fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
351 const struct fscrypt_info *ci)
352{
353 /*
354 * The two smp_load_acquire()'s here pair with the smp_store_release()'s
355 * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key().
356 * I.e., in some cases (namely, if this prep_key is a per-mode
357 * encryption key) another task can publish blk_key or tfm concurrently,
358 * executing a RELEASE barrier. We need to use smp_load_acquire() here
359 * to safely ACQUIRE the memory the other task published.
360 */
361 if (fscrypt_using_inline_encryption(ci))
362 return smp_load_acquire(&prep_key->blk_key) != NULL;
363 return smp_load_acquire(&prep_key->tfm) != NULL;
364}
365
366#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
367
368static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
369{
370 return 0;
371}
372
373static inline bool
374fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
375{
376 return false;
377}
378
379static inline int
380fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
381 const u8 *raw_key,
382 const struct fscrypt_info *ci)
383{
384 WARN_ON(1);
385 return -EOPNOTSUPP;
386}
387
388static inline void
389fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key)
390{
391}
392
393static inline bool
394fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
395 const struct fscrypt_info *ci)
396{
397 return smp_load_acquire(&prep_key->tfm) != NULL;
398}
399#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
400
401/* keyring.c */
402
403/*
404 * fscrypt_master_key_secret - secret key material of an in-use master key
405 */
406struct fscrypt_master_key_secret {
407
408 /*
409 * For v2 policy keys: HKDF context keyed by this master key.
410 * For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
411 */
412 struct fscrypt_hkdf hkdf;
413
414 /* Size of the raw key in bytes. Set even if ->raw isn't set. */
415 u32 size;
416
417 /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
418 u8 raw[FSCRYPT_MAX_KEY_SIZE];
419
420} __randomize_layout;
421
422/*
423 * fscrypt_master_key - an in-use master key
424 *
425 * This represents a master encryption key which has been added to the
426 * filesystem and can be used to "unlock" the encrypted files which were
427 * encrypted with it.
428 */
429struct fscrypt_master_key {
430
431 /*
432 * The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
433 * executed, this is wiped and no new inodes can be unlocked with this
434 * key; however, there may still be inodes in ->mk_decrypted_inodes
435 * which could not be evicted. As long as some inodes still remain,
436 * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
437 * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
438 *
439 * Locking: protected by key->sem (outer) and mk_secret_sem (inner).
440 * The reason for two locks is that key->sem also protects modifying
441 * mk_users, which ranks it above the semaphore for the keyring key
442 * type, which is in turn above page faults (via keyring_read). But
443 * sometimes filesystems call fscrypt_get_encryption_info() from within
444 * a transaction, which ranks it below page faults. So we need a
445 * separate lock which protects mk_secret but not also mk_users.
446 */
447 struct fscrypt_master_key_secret mk_secret;
448 struct rw_semaphore mk_secret_sem;
449
450 /*
451 * For v1 policy keys: an arbitrary key descriptor which was assigned by
452 * userspace (->descriptor).
453 *
454 * For v2 policy keys: a cryptographic hash of this key (->identifier).
455 */
456 struct fscrypt_key_specifier mk_spec;
457
458 /*
459 * Keyring which contains a key of type 'key_type_fscrypt_user' for each
460 * user who has added this key. Normally each key will be added by just
461 * one user, but it's possible that multiple users share a key, and in
462 * that case we need to keep track of those users so that one user can't
463 * remove the key before the others want it removed too.
464 *
465 * This is NULL for v1 policy keys; those can only be added by root.
466 *
467 * Locking: in addition to this keyrings own semaphore, this is
468 * protected by the master key's key->sem, so we can do atomic
469 * search+insert. It can also be searched without taking any locks, but
470 * in that case the returned key may have already been removed.
471 */
472 struct key *mk_users;
473
474 /*
475 * Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
476 * Once this goes to 0, the master key is removed from ->s_master_keys.
477 * The 'struct fscrypt_master_key' will continue to live as long as the
478 * 'struct key' whose payload it is, but we won't let this reference
479 * count rise again.
480 */
481 refcount_t mk_refcount;
482
483 /*
484 * List of inodes that were unlocked using this key. This allows the
485 * inodes to be evicted efficiently if the key is removed.
486 */
487 struct list_head mk_decrypted_inodes;
488 spinlock_t mk_decrypted_inodes_lock;
489
490 /*
491 * Per-mode encryption keys for the various types of encryption policies
492 * that use them. Allocated and derived on-demand.
493 */
494 struct fscrypt_prepared_key mk_direct_keys[__FSCRYPT_MODE_MAX + 1];
495 struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[__FSCRYPT_MODE_MAX + 1];
496 struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[__FSCRYPT_MODE_MAX + 1];
497
498 /* Hash key for inode numbers. Initialized only when needed. */
499 siphash_key_t mk_ino_hash_key;
500 bool mk_ino_hash_key_initialized;
501
502} __randomize_layout;
503
504static inline bool
505is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
506{
507 /*
508 * The READ_ONCE() is only necessary for fscrypt_drop_inode() and
509 * fscrypt_key_describe(). These run in atomic context, so they can't
510 * take ->mk_secret_sem and thus 'secret' can change concurrently which
511 * would be a data race. But they only need to know whether the secret
512 * *was* present at the time of check, so READ_ONCE() suffices.
513 */
514 return READ_ONCE(secret->size) != 0;
515}
516
517static inline const char *master_key_spec_type(
518 const struct fscrypt_key_specifier *spec)
519{
520 switch (spec->type) {
521 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
522 return "descriptor";
523 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
524 return "identifier";
525 }
526 return "[unknown]";
527}
528
529static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
530{
531 switch (spec->type) {
532 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
533 return FSCRYPT_KEY_DESCRIPTOR_SIZE;
534 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
535 return FSCRYPT_KEY_IDENTIFIER_SIZE;
536 }
537 return 0;
538}
539
540struct key *
541fscrypt_find_master_key(struct super_block *sb,
542 const struct fscrypt_key_specifier *mk_spec);
543
544int fscrypt_add_test_dummy_key(struct super_block *sb,
545 struct fscrypt_key_specifier *key_spec);
546
547int fscrypt_verify_key_added(struct super_block *sb,
548 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
549
550int __init fscrypt_init_keyring(void);
551
552/* keysetup.c */
553
554struct fscrypt_mode {
555 const char *friendly_name;
556 const char *cipher_str;
557 int keysize;
558 int ivsize;
559 int logged_impl_name;
560 enum blk_crypto_mode_num blk_crypto_mode;
561};
562
563extern struct fscrypt_mode fscrypt_modes[];
564
565int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
566 const u8 *raw_key, const struct fscrypt_info *ci);
567
568void fscrypt_destroy_prepared_key(struct fscrypt_prepared_key *prep_key);
569
570int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);
571
572int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
573 const struct fscrypt_master_key *mk);
574
575/* keysetup_v1.c */
576
577void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
578
579int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
580 const u8 *raw_master_key);
581
582int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci);
583
584/* policy.c */
585
586bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
587 const union fscrypt_policy *policy2);
588bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
589 const struct inode *inode);
590int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
591 const union fscrypt_context *ctx_u,
592 int ctx_size);
593
594#endif /* _FSCRYPT_PRIVATE_H */