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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
28/* Keep this in sync with include/uapi/linux/fscrypt.h */
29#define FSCRYPT_MODE_MAX FSCRYPT_MODE_ADIANTUM
30
31struct fscrypt_context_v1 {
32 u8 version; /* FSCRYPT_CONTEXT_V1 */
33 u8 contents_encryption_mode;
34 u8 filenames_encryption_mode;
35 u8 flags;
36 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
37 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
38};
39
40struct fscrypt_context_v2 {
41 u8 version; /* FSCRYPT_CONTEXT_V2 */
42 u8 contents_encryption_mode;
43 u8 filenames_encryption_mode;
44 u8 flags;
45 u8 __reserved[4];
46 u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
47 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
48};
49
50/*
51 * fscrypt_context - the encryption context of an inode
52 *
53 * This is the on-disk equivalent of an fscrypt_policy, stored alongside each
54 * encrypted file usually in a hidden extended attribute. It contains the
55 * fields from the fscrypt_policy, in order to identify the encryption algorithm
56 * and key with which the file is encrypted. It also contains a nonce that was
57 * randomly generated by fscrypt itself; this is used as KDF input or as a tweak
58 * to cause different files to be encrypted differently.
59 */
60union fscrypt_context {
61 u8 version;
62 struct fscrypt_context_v1 v1;
63 struct fscrypt_context_v2 v2;
64};
65
66/*
67 * Return the size expected for the given fscrypt_context based on its version
68 * number, or 0 if the context version is unrecognized.
69 */
70static inline int fscrypt_context_size(const union fscrypt_context *ctx)
71{
72 switch (ctx->version) {
73 case FSCRYPT_CONTEXT_V1:
74 BUILD_BUG_ON(sizeof(ctx->v1) != 28);
75 return sizeof(ctx->v1);
76 case FSCRYPT_CONTEXT_V2:
77 BUILD_BUG_ON(sizeof(ctx->v2) != 40);
78 return sizeof(ctx->v2);
79 }
80 return 0;
81}
82
83/* Check whether an fscrypt_context has a recognized version number and size */
84static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx,
85 int ctx_size)
86{
87 return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx);
88}
89
90/* Retrieve the context's nonce, assuming the context was already validated */
91static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx)
92{
93 switch (ctx->version) {
94 case FSCRYPT_CONTEXT_V1:
95 return ctx->v1.nonce;
96 case FSCRYPT_CONTEXT_V2:
97 return ctx->v2.nonce;
98 }
99 WARN_ON(1);
100 return NULL;
101}
102
103union fscrypt_policy {
104 u8 version;
105 struct fscrypt_policy_v1 v1;
106 struct fscrypt_policy_v2 v2;
107};
108
109/*
110 * Return the size expected for the given fscrypt_policy based on its version
111 * number, or 0 if the policy version is unrecognized.
112 */
113static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
114{
115 switch (policy->version) {
116 case FSCRYPT_POLICY_V1:
117 return sizeof(policy->v1);
118 case FSCRYPT_POLICY_V2:
119 return sizeof(policy->v2);
120 }
121 return 0;
122}
123
124/* Return the contents encryption mode of a valid encryption policy */
125static inline u8
126fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
127{
128 switch (policy->version) {
129 case FSCRYPT_POLICY_V1:
130 return policy->v1.contents_encryption_mode;
131 case FSCRYPT_POLICY_V2:
132 return policy->v2.contents_encryption_mode;
133 }
134 BUG();
135}
136
137/* Return the filenames encryption mode of a valid encryption policy */
138static inline u8
139fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
140{
141 switch (policy->version) {
142 case FSCRYPT_POLICY_V1:
143 return policy->v1.filenames_encryption_mode;
144 case FSCRYPT_POLICY_V2:
145 return policy->v2.filenames_encryption_mode;
146 }
147 BUG();
148}
149
150/* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */
151static inline u8
152fscrypt_policy_flags(const union fscrypt_policy *policy)
153{
154 switch (policy->version) {
155 case FSCRYPT_POLICY_V1:
156 return policy->v1.flags;
157 case FSCRYPT_POLICY_V2:
158 return policy->v2.flags;
159 }
160 BUG();
161}
162
163/*
164 * For encrypted symlinks, the ciphertext length is stored at the beginning
165 * of the string in little-endian format.
166 */
167struct fscrypt_symlink_data {
168 __le16 len;
169 char encrypted_path[1];
170} __packed;
171
172/**
173 * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption
174 * @tfm: crypto API transform object
175 * @blk_key: key for blk-crypto
176 *
177 * Normally only one of the fields will be non-NULL.
178 */
179struct fscrypt_prepared_key {
180 struct crypto_skcipher *tfm;
181#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
182 struct fscrypt_blk_crypto_key *blk_key;
183#endif
184};
185
186/*
187 * fscrypt_info - the "encryption key" for an inode
188 *
189 * When an encrypted file's key is made available, an instance of this struct is
190 * allocated and stored in ->i_crypt_info. Once created, it remains until the
191 * inode is evicted.
192 */
193struct fscrypt_info {
194
195 /* The key in a form prepared for actual encryption/decryption */
196 struct fscrypt_prepared_key ci_enc_key;
197
198 /* True if ci_enc_key should be freed when this fscrypt_info is freed */
199 bool ci_owns_key;
200
201#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
202 /*
203 * True if this inode will use inline encryption (blk-crypto) instead of
204 * the traditional filesystem-layer encryption.
205 */
206 bool ci_inlinecrypt;
207#endif
208
209 /*
210 * Encryption mode used for this inode. It corresponds to either the
211 * contents or filenames encryption mode, depending on the inode type.
212 */
213 struct fscrypt_mode *ci_mode;
214
215 /* Back-pointer to the inode */
216 struct inode *ci_inode;
217
218 /*
219 * The master key with which this inode was unlocked (decrypted). This
220 * will be NULL if the master key was found in a process-subscribed
221 * keyring rather than in the filesystem-level keyring.
222 */
223 struct key *ci_master_key;
224
225 /*
226 * Link in list of inodes that were unlocked with the master key.
227 * Only used when ->ci_master_key is set.
228 */
229 struct list_head ci_master_key_link;
230
231 /*
232 * If non-NULL, then encryption is done using the master key directly
233 * and ci_enc_key will equal ci_direct_key->dk_key.
234 */
235 struct fscrypt_direct_key *ci_direct_key;
236
237 /*
238 * This inode's hash key for filenames. This is a 128-bit SipHash-2-4
239 * key. This is only set for directories that use a keyed dirhash over
240 * the plaintext filenames -- currently just casefolded directories.
241 */
242 siphash_key_t ci_dirhash_key;
243 bool ci_dirhash_key_initialized;
244
245 /* The encryption policy used by this inode */
246 union fscrypt_policy ci_policy;
247
248 /* This inode's nonce, copied from the fscrypt_context */
249 u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
250
251 /* Hashed inode number. Only set for IV_INO_LBLK_32 */
252 u32 ci_hashed_ino;
253};
254
255typedef enum {
256 FS_DECRYPT = 0,
257 FS_ENCRYPT,
258} fscrypt_direction_t;
259
260/* crypto.c */
261extern struct kmem_cache *fscrypt_info_cachep;
262int fscrypt_initialize(unsigned int cop_flags);
263int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
264 u64 lblk_num, struct page *src_page,
265 struct page *dest_page, unsigned int len,
266 unsigned int offs, gfp_t gfp_flags);
267struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
268
269void __printf(3, 4) __cold
270fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
271
272#define fscrypt_warn(inode, fmt, ...) \
273 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
274#define fscrypt_err(inode, fmt, ...) \
275 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
276
277#define FSCRYPT_MAX_IV_SIZE 32
278
279union fscrypt_iv {
280 struct {
281 /* logical block number within the file */
282 __le64 lblk_num;
283
284 /* per-file nonce; only set in DIRECT_KEY mode */
285 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
286 };
287 u8 raw[FSCRYPT_MAX_IV_SIZE];
288 __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)];
289};
290
291void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
292 const struct fscrypt_info *ci);
293
294/* fname.c */
295int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
296 u8 *out, unsigned int olen);
297bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
298 u32 orig_len, u32 max_len,
299 u32 *encrypted_len_ret);
300
301/* hkdf.c */
302
303struct fscrypt_hkdf {
304 struct crypto_shash *hmac_tfm;
305};
306
307int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
308 unsigned int master_key_size);
309
310/*
311 * The list of contexts in which fscrypt uses HKDF. These values are used as
312 * the first byte of the HKDF application-specific info string to guarantee that
313 * info strings are never repeated between contexts. This ensures that all HKDF
314 * outputs are unique and cryptographically isolated, i.e. knowledge of one
315 * output doesn't reveal another.
316 */
317#define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */
318#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */
319#define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */
320#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */
321#define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */
322#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */
323#define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */
324
325int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
326 const u8 *info, unsigned int infolen,
327 u8 *okm, unsigned int okmlen);
328
329void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
330
331/* inline_crypt.c */
332#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
333int fscrypt_select_encryption_impl(struct fscrypt_info *ci);
334
335static inline bool
336fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
337{
338 return ci->ci_inlinecrypt;
339}
340
341int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
342 const u8 *raw_key,
343 const struct fscrypt_info *ci);
344
345void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key);
346
347/*
348 * Check whether the crypto transform or blk-crypto key has been allocated in
349 * @prep_key, depending on which encryption implementation the file will use.
350 */
351static inline bool
352fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
353 const struct fscrypt_info *ci)
354{
355 /*
356 * The two smp_load_acquire()'s here pair with the smp_store_release()'s
357 * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key().
358 * I.e., in some cases (namely, if this prep_key is a per-mode
359 * encryption key) another task can publish blk_key or tfm concurrently,
360 * executing a RELEASE barrier. We need to use smp_load_acquire() here
361 * to safely ACQUIRE the memory the other task published.
362 */
363 if (fscrypt_using_inline_encryption(ci))
364 return smp_load_acquire(&prep_key->blk_key) != NULL;
365 return smp_load_acquire(&prep_key->tfm) != NULL;
366}
367
368#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
369
370static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
371{
372 return 0;
373}
374
375static inline bool
376fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
377{
378 return false;
379}
380
381static inline int
382fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
383 const u8 *raw_key,
384 const struct fscrypt_info *ci)
385{
386 WARN_ON(1);
387 return -EOPNOTSUPP;
388}
389
390static inline void
391fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key)
392{
393}
394
395static inline bool
396fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
397 const struct fscrypt_info *ci)
398{
399 return smp_load_acquire(&prep_key->tfm) != NULL;
400}
401#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
402
403/* keyring.c */
404
405/*
406 * fscrypt_master_key_secret - secret key material of an in-use master key
407 */
408struct fscrypt_master_key_secret {
409
410 /*
411 * For v2 policy keys: HKDF context keyed by this master key.
412 * For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
413 */
414 struct fscrypt_hkdf hkdf;
415
416 /* Size of the raw key in bytes. Set even if ->raw isn't set. */
417 u32 size;
418
419 /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
420 u8 raw[FSCRYPT_MAX_KEY_SIZE];
421
422} __randomize_layout;
423
424/*
425 * fscrypt_master_key - an in-use master key
426 *
427 * This represents a master encryption key which has been added to the
428 * filesystem and can be used to "unlock" the encrypted files which were
429 * encrypted with it.
430 */
431struct fscrypt_master_key {
432
433 /*
434 * The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
435 * executed, this is wiped and no new inodes can be unlocked with this
436 * key; however, there may still be inodes in ->mk_decrypted_inodes
437 * which could not be evicted. As long as some inodes still remain,
438 * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
439 * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
440 *
441 * Locking: protected by this master key's key->sem.
442 */
443 struct fscrypt_master_key_secret mk_secret;
444
445 /*
446 * For v1 policy keys: an arbitrary key descriptor which was assigned by
447 * userspace (->descriptor).
448 *
449 * For v2 policy keys: a cryptographic hash of this key (->identifier).
450 */
451 struct fscrypt_key_specifier mk_spec;
452
453 /*
454 * Keyring which contains a key of type 'key_type_fscrypt_user' for each
455 * user who has added this key. Normally each key will be added by just
456 * one user, but it's possible that multiple users share a key, and in
457 * that case we need to keep track of those users so that one user can't
458 * remove the key before the others want it removed too.
459 *
460 * This is NULL for v1 policy keys; those can only be added by root.
461 *
462 * Locking: in addition to this keyring's own semaphore, this is
463 * protected by this master key's key->sem, so we can do atomic
464 * search+insert. It can also be searched without taking any locks, but
465 * in that case the returned key may have already been removed.
466 */
467 struct key *mk_users;
468
469 /*
470 * Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
471 * Once this goes to 0, the master key is removed from ->s_master_keys.
472 * The 'struct fscrypt_master_key' will continue to live as long as the
473 * 'struct key' whose payload it is, but we won't let this reference
474 * count rise again.
475 */
476 refcount_t mk_refcount;
477
478 /*
479 * List of inodes that were unlocked using this key. This allows the
480 * inodes to be evicted efficiently if the key is removed.
481 */
482 struct list_head mk_decrypted_inodes;
483 spinlock_t mk_decrypted_inodes_lock;
484
485 /*
486 * Per-mode encryption keys for the various types of encryption policies
487 * that use them. Allocated and derived on-demand.
488 */
489 struct fscrypt_prepared_key mk_direct_keys[FSCRYPT_MODE_MAX + 1];
490 struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[FSCRYPT_MODE_MAX + 1];
491 struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[FSCRYPT_MODE_MAX + 1];
492
493 /* Hash key for inode numbers. Initialized only when needed. */
494 siphash_key_t mk_ino_hash_key;
495 bool mk_ino_hash_key_initialized;
496
497} __randomize_layout;
498
499static inline bool
500is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
501{
502 /*
503 * The READ_ONCE() is only necessary for fscrypt_drop_inode() and
504 * fscrypt_key_describe(). These run in atomic context, so they can't
505 * take the key semaphore and thus 'secret' can change concurrently
506 * which would be a data race. But they only need to know whether the
507 * secret *was* present at the time of check, so READ_ONCE() suffices.
508 */
509 return READ_ONCE(secret->size) != 0;
510}
511
512static inline const char *master_key_spec_type(
513 const struct fscrypt_key_specifier *spec)
514{
515 switch (spec->type) {
516 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
517 return "descriptor";
518 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
519 return "identifier";
520 }
521 return "[unknown]";
522}
523
524static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
525{
526 switch (spec->type) {
527 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
528 return FSCRYPT_KEY_DESCRIPTOR_SIZE;
529 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
530 return FSCRYPT_KEY_IDENTIFIER_SIZE;
531 }
532 return 0;
533}
534
535struct key *
536fscrypt_find_master_key(struct super_block *sb,
537 const struct fscrypt_key_specifier *mk_spec);
538
539int fscrypt_add_test_dummy_key(struct super_block *sb,
540 struct fscrypt_key_specifier *key_spec);
541
542int fscrypt_verify_key_added(struct super_block *sb,
543 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
544
545int __init fscrypt_init_keyring(void);
546
547/* keysetup.c */
548
549struct fscrypt_mode {
550 const char *friendly_name;
551 const char *cipher_str;
552 int keysize;
553 int ivsize;
554 int logged_impl_name;
555 enum blk_crypto_mode_num blk_crypto_mode;
556};
557
558extern struct fscrypt_mode fscrypt_modes[];
559
560int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
561 const u8 *raw_key, const struct fscrypt_info *ci);
562
563void fscrypt_destroy_prepared_key(struct fscrypt_prepared_key *prep_key);
564
565int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);
566
567int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
568 const struct fscrypt_master_key *mk);
569
570void fscrypt_hash_inode_number(struct fscrypt_info *ci,
571 const struct fscrypt_master_key *mk);
572
573int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported);
574
575/**
576 * fscrypt_require_key() - require an inode's encryption key
577 * @inode: the inode we need the key for
578 *
579 * If the inode is encrypted, set up its encryption key if not already done.
580 * Then require that the key be present and return -ENOKEY otherwise.
581 *
582 * No locks are needed, and the key will live as long as the struct inode --- so
583 * it won't go away from under you.
584 *
585 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
586 * if a problem occurred while setting up the encryption key.
587 */
588static inline int fscrypt_require_key(struct inode *inode)
589{
590 if (IS_ENCRYPTED(inode)) {
591 int err = fscrypt_get_encryption_info(inode, false);
592
593 if (err)
594 return err;
595 if (!fscrypt_has_encryption_key(inode))
596 return -ENOKEY;
597 }
598 return 0;
599}
600
601/* keysetup_v1.c */
602
603void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
604
605int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
606 const u8 *raw_master_key);
607
608int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci);
609
610/* policy.c */
611
612bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
613 const union fscrypt_policy *policy2);
614bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
615 const struct inode *inode);
616int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
617 const union fscrypt_context *ctx_u,
618 int ctx_size);
619const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir);
620
621#endif /* _FSCRYPT_PRIVATE_H */