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 <crypto/sha2.h> 15 #include <linux/fscrypt.h> 16 #include <linux/minmax.h> 17 #include <linux/siphash.h> 18 #include <linux/blk-crypto.h> 19 20 #define CONST_STRLEN(str) (sizeof(str) - 1) 21 22 #define FSCRYPT_FILE_NONCE_SIZE 16 23 24 /* 25 * Minimum size of an fscrypt master key. Note: a longer key will be required 26 * if ciphers with a 256-bit security strength are used. This is just the 27 * absolute minimum, which applies when only 128-bit encryption is used. 28 */ 29 #define FSCRYPT_MIN_KEY_SIZE 16 30 31 /* Maximum size of a raw fscrypt master key */ 32 #define FSCRYPT_MAX_RAW_KEY_SIZE 64 33 34 /* Maximum size of a hardware-wrapped fscrypt master key */ 35 #define FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE 36 37 /* Maximum size of an fscrypt master key across both key types */ 38 #define FSCRYPT_MAX_ANY_KEY_SIZE \ 39 MAX(FSCRYPT_MAX_RAW_KEY_SIZE, FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE) 40 41 /* 42 * FSCRYPT_MAX_KEY_SIZE is defined in the UAPI header, but the addition of 43 * hardware-wrapped keys has made it misleading as it's only for raw keys. 44 * Don't use it in kernel code; use one of the above constants instead. 45 */ 46 #undef FSCRYPT_MAX_KEY_SIZE 47 48 /* 49 * This mask is passed as the third argument to the crypto_alloc_*() functions 50 * to prevent fscrypt from using the Crypto API drivers for non-inline crypto 51 * engines. Those drivers have been problematic for fscrypt. fscrypt users 52 * have reported hangs and even incorrect en/decryption with these drivers. 53 * Since going to the driver, off CPU, and back again is really slow, such 54 * drivers can be over 50 times slower than the CPU-based code for fscrypt's 55 * workload. Even on platforms that lack AES instructions on the CPU, using the 56 * offloads has been shown to be slower, even staying with AES. (Of course, 57 * Adiantum is faster still, and is the recommended option on such platforms...) 58 * 59 * Note that fscrypt also supports inline crypto engines. Those don't use the 60 * Crypto API and work much better than the old-style (non-inline) engines. 61 */ 62 #define FSCRYPT_CRYPTOAPI_MASK \ 63 (CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY | \ 64 CRYPTO_ALG_KERN_DRIVER_ONLY) 65 66 #define FSCRYPT_CONTEXT_V1 1 67 #define FSCRYPT_CONTEXT_V2 2 68 69 struct fscrypt_context_v1 { 70 u8 version; /* FSCRYPT_CONTEXT_V1 */ 71 u8 contents_encryption_mode; 72 u8 filenames_encryption_mode; 73 u8 flags; 74 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE]; 75 u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; 76 }; 77 78 struct fscrypt_context_v2 { 79 u8 version; /* FSCRYPT_CONTEXT_V2 */ 80 u8 contents_encryption_mode; 81 u8 filenames_encryption_mode; 82 u8 flags; 83 u8 log2_data_unit_size; 84 u8 __reserved[3]; 85 u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]; 86 u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; 87 }; 88 89 /* 90 * fscrypt_context - the encryption context of an inode 91 * 92 * This is the on-disk equivalent of an fscrypt_policy, stored alongside each 93 * encrypted file usually in a hidden extended attribute. It contains the 94 * fields from the fscrypt_policy, in order to identify the encryption algorithm 95 * and key with which the file is encrypted. It also contains a nonce that was 96 * randomly generated by fscrypt itself; this is used as KDF input or as a tweak 97 * to cause different files to be encrypted differently. 98 */ 99 union fscrypt_context { 100 u8 version; 101 struct fscrypt_context_v1 v1; 102 struct fscrypt_context_v2 v2; 103 }; 104 105 /* 106 * Return the size expected for the given fscrypt_context based on its version 107 * number, or 0 if the context version is unrecognized. 108 */ 109 static inline int fscrypt_context_size(const union fscrypt_context *ctx) 110 { 111 switch (ctx->version) { 112 case FSCRYPT_CONTEXT_V1: 113 BUILD_BUG_ON(sizeof(ctx->v1) != 28); 114 return sizeof(ctx->v1); 115 case FSCRYPT_CONTEXT_V2: 116 BUILD_BUG_ON(sizeof(ctx->v2) != 40); 117 return sizeof(ctx->v2); 118 } 119 return 0; 120 } 121 122 /* Check whether an fscrypt_context has a recognized version number and size */ 123 static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx, 124 int ctx_size) 125 { 126 return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx); 127 } 128 129 /* Retrieve the context's nonce, assuming the context was already validated */ 130 static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx) 131 { 132 switch (ctx->version) { 133 case FSCRYPT_CONTEXT_V1: 134 return ctx->v1.nonce; 135 case FSCRYPT_CONTEXT_V2: 136 return ctx->v2.nonce; 137 } 138 WARN_ON_ONCE(1); 139 return NULL; 140 } 141 142 union fscrypt_policy { 143 u8 version; 144 struct fscrypt_policy_v1 v1; 145 struct fscrypt_policy_v2 v2; 146 }; 147 148 /* 149 * Return the size expected for the given fscrypt_policy based on its version 150 * number, or 0 if the policy version is unrecognized. 151 */ 152 static inline int fscrypt_policy_size(const union fscrypt_policy *policy) 153 { 154 switch (policy->version) { 155 case FSCRYPT_POLICY_V1: 156 return sizeof(policy->v1); 157 case FSCRYPT_POLICY_V2: 158 return sizeof(policy->v2); 159 } 160 return 0; 161 } 162 163 /* Return the contents encryption mode of a valid encryption policy */ 164 static inline u8 165 fscrypt_policy_contents_mode(const union fscrypt_policy *policy) 166 { 167 switch (policy->version) { 168 case FSCRYPT_POLICY_V1: 169 return policy->v1.contents_encryption_mode; 170 case FSCRYPT_POLICY_V2: 171 return policy->v2.contents_encryption_mode; 172 } 173 BUG(); 174 } 175 176 /* Return the filenames encryption mode of a valid encryption policy */ 177 static inline u8 178 fscrypt_policy_fnames_mode(const union fscrypt_policy *policy) 179 { 180 switch (policy->version) { 181 case FSCRYPT_POLICY_V1: 182 return policy->v1.filenames_encryption_mode; 183 case FSCRYPT_POLICY_V2: 184 return policy->v2.filenames_encryption_mode; 185 } 186 BUG(); 187 } 188 189 /* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */ 190 static inline u8 191 fscrypt_policy_flags(const union fscrypt_policy *policy) 192 { 193 switch (policy->version) { 194 case FSCRYPT_POLICY_V1: 195 return policy->v1.flags; 196 case FSCRYPT_POLICY_V2: 197 return policy->v2.flags; 198 } 199 BUG(); 200 } 201 202 static inline int 203 fscrypt_policy_v2_du_bits(const struct fscrypt_policy_v2 *policy, 204 const struct inode *inode) 205 { 206 return policy->log2_data_unit_size ?: inode->i_blkbits; 207 } 208 209 static inline int 210 fscrypt_policy_du_bits(const union fscrypt_policy *policy, 211 const struct inode *inode) 212 { 213 switch (policy->version) { 214 case FSCRYPT_POLICY_V1: 215 return inode->i_blkbits; 216 case FSCRYPT_POLICY_V2: 217 return fscrypt_policy_v2_du_bits(&policy->v2, inode); 218 } 219 BUG(); 220 } 221 222 /** 223 * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption 224 * @tfm: crypto API transform object 225 * @blk_key: key for blk-crypto 226 * 227 * Only one of the fields is non-NULL. 228 */ 229 struct fscrypt_prepared_key { 230 struct crypto_sync_skcipher *tfm; 231 #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT 232 struct blk_crypto_key *blk_key; 233 #endif 234 }; 235 236 /* An entry in the linked list ->mk_mode_keys */ 237 struct fscrypt_mode_key { 238 struct fscrypt_prepared_key key; 239 struct list_head link; 240 u8 hkdf_context; 241 u8 mode_num; 242 u8 data_unit_bits; 243 }; 244 245 /* 246 * fscrypt_inode_info - the "encryption key" for an inode 247 * 248 * When an encrypted file's key is made available, an instance of this struct is 249 * allocated and a pointer to it is stored in the file's in-memory inode. Once 250 * created, it remains until the inode is evicted. 251 */ 252 struct fscrypt_inode_info { 253 254 /* The key in a form prepared for actual encryption/decryption */ 255 struct fscrypt_prepared_key ci_enc_key; 256 257 /* True if ci_enc_key should be freed when this struct is freed */ 258 u8 ci_owns_key : 1; 259 260 /* True if ci_dirhash_key is initialized */ 261 u8 ci_dirhash_key_initialized : 1; 262 263 /* 264 * log2 of the data unit size (granularity of contents encryption) of 265 * this file. This is computable from ci_policy and ci_inode but is 266 * cached here for efficiency. Only used for regular files. 267 */ 268 u8 ci_data_unit_bits; 269 270 /* Hashed inode number. Only set for IV_INO_LBLK_32 */ 271 u32 ci_hashed_ino; 272 273 /* 274 * Encryption mode used for this inode. It corresponds to either the 275 * contents or filenames encryption mode, depending on the inode type. 276 */ 277 struct fscrypt_mode *ci_mode; 278 279 /* Back-pointer to the inode */ 280 struct inode *ci_inode; 281 282 /* 283 * The master key with which this inode was unlocked (decrypted). This 284 * will be NULL if the master key was found in a process-subscribed 285 * keyring rather than in the filesystem-level keyring. 286 */ 287 struct fscrypt_master_key *ci_master_key; 288 289 /* 290 * Link in list of inodes that were unlocked with the master key. 291 * Only used when ->ci_master_key is set. 292 */ 293 struct list_head ci_master_key_link; 294 295 /* 296 * If non-NULL, then encryption is done using the master key directly 297 * and ci_enc_key will equal ci_direct_key->dk_key. 298 */ 299 struct fscrypt_direct_key *ci_direct_key; 300 301 /* 302 * This inode's hash key for filenames. This is a 128-bit SipHash-2-4 303 * key. This is only set for directories that use a keyed dirhash over 304 * the plaintext filenames -- currently just casefolded directories. 305 */ 306 siphash_key_t ci_dirhash_key; 307 308 /* The encryption policy used by this inode */ 309 union fscrypt_policy ci_policy; 310 311 /* This inode's nonce, copied from the fscrypt_context */ 312 u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE]; 313 }; 314 315 /* crypto.c */ 316 extern struct kmem_cache *fscrypt_inode_info_cachep; 317 int fscrypt_initialize(struct super_block *sb); 318 319 void __printf(3, 4) __cold 320 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...); 321 322 #define fscrypt_warn(inode, fmt, ...) \ 323 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__) 324 #define fscrypt_err(inode, fmt, ...) \ 325 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__) 326 327 #define FSCRYPT_MAX_IV_SIZE 32 328 329 union fscrypt_iv { 330 struct { 331 /* zero-based index of data unit within the file */ 332 __le64 index; 333 334 /* per-file nonce; only set in DIRECT_KEY mode */ 335 u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; 336 }; 337 u8 raw[FSCRYPT_MAX_IV_SIZE]; 338 __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)]; 339 }; 340 341 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index, 342 const struct fscrypt_inode_info *ci); 343 344 /* 345 * Return the number of bits used by the maximum file data unit index that is 346 * possible on the given filesystem, using the given log2 data unit size. 347 */ 348 static inline int 349 fscrypt_max_file_dun_bits(const struct super_block *sb, int du_bits) 350 { 351 return fls64(sb->s_maxbytes - 1) - du_bits; 352 } 353 354 /* fname.c */ 355 bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, 356 u32 orig_len, u32 max_len, 357 u32 *encrypted_len_ret); 358 359 /* hkdf.c */ 360 void fscrypt_init_hkdf(struct hmac_sha512_key *hkdf, const u8 *master_key, 361 unsigned int master_key_size); 362 363 /* 364 * The list of contexts in which fscrypt uses HKDF. These values are used as 365 * the first byte of the HKDF application-specific info string to guarantee that 366 * info strings are never repeated between contexts. This ensures that all HKDF 367 * outputs are unique and cryptographically isolated, i.e. knowledge of one 368 * output doesn't reveal another. 369 */ 370 #define HKDF_CONTEXT_KEY_IDENTIFIER_FOR_RAW_KEY 1 /* info=<empty> */ 371 #define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */ 372 #define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */ 373 #define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */ 374 #define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */ 375 #define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */ 376 #define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */ 377 #define HKDF_CONTEXT_KEY_IDENTIFIER_FOR_HW_WRAPPED_KEY \ 378 8 /* info=<empty> */ 379 380 void fscrypt_hkdf_expand(const struct hmac_sha512_key *hkdf, u8 context, 381 const u8 *info, unsigned int infolen, 382 u8 *okm, unsigned int okmlen); 383 384 /* block.c */ 385 #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT 386 static inline bool 387 fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci) 388 { 389 const struct inode *inode = ci->ci_inode; 390 391 return S_ISREG(inode->i_mode) && inode->i_sb->s_cop->is_block_based; 392 } 393 394 int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, 395 const u8 *key_bytes, size_t key_size, 396 bool is_hw_wrapped, 397 const struct fscrypt_inode_info *ci); 398 399 void fscrypt_destroy_inline_crypt_key(struct super_block *sb, 400 struct fscrypt_prepared_key *prep_key); 401 402 int fscrypt_derive_sw_secret(struct super_block *sb, 403 const u8 *wrapped_key, size_t wrapped_key_size, 404 u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]); 405 406 /* 407 * Check whether the crypto transform or blk-crypto key has been allocated in 408 * @prep_key, depending on which encryption implementation the file will use. 409 */ 410 static inline bool 411 fscrypt_is_key_prepared(const struct fscrypt_prepared_key *prep_key, 412 const struct fscrypt_inode_info *ci) 413 { 414 if (fscrypt_using_inline_encryption(ci)) 415 return prep_key->blk_key != NULL; 416 return prep_key->tfm != NULL; 417 } 418 419 #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ 420 421 static inline bool 422 fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci) 423 { 424 return false; 425 } 426 427 static inline int 428 fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, 429 const u8 *key_bytes, size_t key_size, 430 bool is_hw_wrapped, 431 const struct fscrypt_inode_info *ci) 432 { 433 WARN_ON_ONCE(1); 434 return -EOPNOTSUPP; 435 } 436 437 static inline void 438 fscrypt_destroy_inline_crypt_key(struct super_block *sb, 439 struct fscrypt_prepared_key *prep_key) 440 { 441 } 442 443 static inline int 444 fscrypt_derive_sw_secret(struct super_block *sb, 445 const u8 *wrapped_key, size_t wrapped_key_size, 446 u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]) 447 { 448 fscrypt_warn(NULL, "kernel doesn't support hardware-wrapped keys"); 449 return -EOPNOTSUPP; 450 } 451 452 static inline bool 453 fscrypt_is_key_prepared(const struct fscrypt_prepared_key *prep_key, 454 const struct fscrypt_inode_info *ci) 455 { 456 return prep_key->tfm != NULL; 457 } 458 #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ 459 460 /* keyring.c */ 461 462 /* 463 * fscrypt_master_key_secret - secret key material of an in-use master key 464 */ 465 struct fscrypt_master_key_secret { 466 467 /* 468 * The KDF with which subkeys of this key can be derived. 469 * 470 * For v1 policy keys, this isn't applicable and won't be set. 471 * Otherwise, this KDF will be keyed by this master key if 472 * ->is_hw_wrapped=false, or by the "software secret" that hardware 473 * derived from this master key if ->is_hw_wrapped=true. 474 */ 475 struct hmac_sha512_key hkdf; 476 477 /* 478 * True if this key is a hardware-wrapped key; false if this key is a 479 * raw key (i.e. a "software key"). For v1 policy keys this will always 480 * be false, as v1 policy support is a legacy feature which doesn't 481 * support newer functionality such as hardware-wrapped keys. 482 */ 483 bool is_hw_wrapped; 484 485 /* 486 * Size of the key in bytes. This remains set even if ->bytes was 487 * zeroized due to no longer being needed. I.e. we still remember the 488 * size of the key even if we don't need to remember the key itself. 489 */ 490 u32 size; 491 492 /* 493 * The bytes of the key, when still needed. This can be either a raw 494 * key or a hardware-wrapped key, as indicated by ->is_hw_wrapped. In 495 * the case of a raw, v2 policy key, there is no need to remember the 496 * actual key separately from ->hkdf so this field will be zeroized as 497 * soon as ->hkdf is initialized. 498 */ 499 u8 bytes[FSCRYPT_MAX_ANY_KEY_SIZE]; 500 501 } __randomize_layout; 502 503 /* 504 * fscrypt_master_key - an in-use master key 505 * 506 * This represents a master encryption key which has been added to the 507 * filesystem. There are three high-level states that a key can be in: 508 * 509 * FSCRYPT_KEY_STATUS_PRESENT 510 * Key is fully usable; it can be used to unlock inodes that are encrypted 511 * with it (this includes being able to create new inodes). ->mk_present 512 * indicates whether the key is in this state. ->mk_secret exists, the key 513 * is in the keyring, and ->mk_active_refs > 0 due to ->mk_present. 514 * 515 * FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED 516 * Removal of this key has been initiated, but some inodes that were 517 * unlocked with it are still in-use. Like ABSENT, ->mk_secret is wiped, 518 * and the key can no longer be used to unlock inodes. Unlike ABSENT, the 519 * key is still in the keyring; ->mk_decrypted_inodes is nonempty; and 520 * ->mk_active_refs > 0, being equal to the size of ->mk_decrypted_inodes. 521 * 522 * This state transitions to ABSENT if ->mk_decrypted_inodes becomes empty, 523 * or to PRESENT if FS_IOC_ADD_ENCRYPTION_KEY is called again for this key. 524 * 525 * FSCRYPT_KEY_STATUS_ABSENT 526 * Key is fully removed. The key is no longer in the keyring, 527 * ->mk_decrypted_inodes is empty, ->mk_active_refs == 0, ->mk_secret is 528 * wiped, and the key can no longer be used to unlock inodes. 529 */ 530 struct fscrypt_master_key { 531 532 /* 533 * Link in ->s_master_keys->key_hashtable. 534 * Only valid if ->mk_active_refs > 0. 535 */ 536 struct hlist_node mk_node; 537 538 /* Semaphore that protects ->mk_secret, ->mk_users, and ->mk_present */ 539 struct rw_semaphore mk_sem; 540 541 /* 542 * Active and structural reference counts. An active ref guarantees 543 * that the struct continues to exist, continues to be in the keyring 544 * ->s_master_keys, and that any non-file-scoped subkeys (e.g. 545 * ->mk_mode_keys) that have been prepared continue to exist. 546 * A structural ref only guarantees that the struct continues to exist. 547 * 548 * There is one active ref associated with ->mk_present being true, and 549 * one active ref for each inode in ->mk_decrypted_inodes. 550 * 551 * There is one structural ref associated with the active refcount being 552 * nonzero. Finding a key in the keyring also takes a structural ref, 553 * which is then held temporarily while the key is operated on. 554 */ 555 refcount_t mk_active_refs; 556 refcount_t mk_struct_refs; 557 558 struct rcu_head mk_rcu_head; 559 560 /* 561 * The secret key material. Wiped as soon as it is no longer needed; 562 * for details, see the fscrypt_master_key struct comment. 563 * 564 * Locking: protected by ->mk_sem. 565 */ 566 struct fscrypt_master_key_secret mk_secret; 567 568 /* 569 * For v1 policy keys: an arbitrary key descriptor which was assigned by 570 * userspace (->descriptor). 571 * 572 * For v2 policy keys: a cryptographic hash of this key (->identifier). 573 */ 574 struct fscrypt_key_specifier mk_spec; 575 576 /* 577 * List of user claims to this key (struct fscrypt_master_key_user). 578 * Normally each key will be added by just one user, but it's possible 579 * that multiple users share a key, and in that case we need to keep 580 * track of those users so that one user can't remove the key before the 581 * others want it removed too. 582 * 583 * Used only for v2 policy keys. v1 policy keys can be added only by 584 * root, so user tracking doesn't apply to them. 585 * 586 * Locking: protected by ->mk_sem. 587 */ 588 struct list_head mk_users; 589 590 /* 591 * List of inodes that were unlocked using this key. This allows the 592 * inodes to be evicted efficiently if the key is removed. 593 */ 594 struct list_head mk_decrypted_inodes; 595 spinlock_t mk_decrypted_inodes_lock; 596 597 /* 598 * A list of 'struct fscrypt_mode_key' for the (hkdf_context, mode_num, 599 * data_unit_bits, inlinecrypt) combinations that are in use for this 600 * master key, for hkdf_context in [HKDF_CONTEXT_DIRECT_KEY, 601 * HKDF_CONTEXT_IV_INO_LBLK_32_KEY, HKDF_CONTEXT_IV_INO_LBLK_64_KEY]. 602 * 603 * This is a linked list and not a hash table because in practice 604 * there's just a single encryption policy per master key, using 605 * _at most_ 2 nodes in this list. Per-file keys don't use this at all. 606 * 607 * This list is append-only until the master key is fully removed, at 608 * which time the list is cleared. Before then, 609 * fscrypt_mode_key_setup_mutex synchronizes appends, and searches use 610 * the RCU read lock together with ->mk_sem held for read. 611 */ 612 struct list_head mk_mode_keys; 613 614 /* Hash key for inode numbers. Initialized only when needed. */ 615 siphash_key_t mk_ino_hash_key; 616 bool mk_ino_hash_key_initialized; 617 618 /* 619 * Whether this key is in the "present" state, i.e. fully usable. For 620 * details, see the fscrypt_master_key struct comment. 621 * 622 * Locking: protected by ->mk_sem, but can be read locklessly using 623 * READ_ONCE(). Writers must use WRITE_ONCE() when concurrent readers 624 * are possible. 625 */ 626 bool mk_present; 627 628 } __randomize_layout; 629 630 static inline const char *master_key_spec_type( 631 const struct fscrypt_key_specifier *spec) 632 { 633 switch (spec->type) { 634 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: 635 return "descriptor"; 636 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: 637 return "identifier"; 638 } 639 return "[unknown]"; 640 } 641 642 static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec) 643 { 644 switch (spec->type) { 645 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: 646 return FSCRYPT_KEY_DESCRIPTOR_SIZE; 647 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: 648 return FSCRYPT_KEY_IDENTIFIER_SIZE; 649 } 650 return 0; 651 } 652 653 void fscrypt_put_master_key(struct fscrypt_master_key *mk); 654 655 void fscrypt_put_master_key_activeref(struct super_block *sb, 656 struct fscrypt_master_key *mk); 657 658 struct fscrypt_master_key * 659 fscrypt_find_master_key(struct super_block *sb, 660 const struct fscrypt_key_specifier *mk_spec); 661 662 void fscrypt_get_test_dummy_key_identifier( 663 u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); 664 665 int fscrypt_add_test_dummy_key(struct super_block *sb, 666 struct fscrypt_key_specifier *key_spec); 667 668 int fscrypt_verify_key_added(struct super_block *sb, 669 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); 670 671 void __init fscrypt_init_keyring(void); 672 673 /* keysetup.c */ 674 675 struct fscrypt_mode { 676 const char *friendly_name; 677 const char *cipher_str; 678 int keysize; /* key size in bytes */ 679 int security_strength; /* security strength in bytes */ 680 int ivsize; /* IV size in bytes */ 681 int logged_cryptoapi_impl; 682 int logged_blk_crypto_native; 683 int logged_blk_crypto_fallback; 684 enum blk_crypto_mode_num blk_crypto_mode; 685 }; 686 687 extern struct fscrypt_mode fscrypt_modes[]; 688 689 int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, 690 const u8 *raw_key, const struct fscrypt_inode_info *ci); 691 692 void fscrypt_destroy_prepared_key(struct super_block *sb, 693 struct fscrypt_prepared_key *prep_key); 694 695 int fscrypt_set_per_file_enc_key(struct fscrypt_inode_info *ci, 696 const u8 *raw_key); 697 698 void fscrypt_derive_dirhash_key(struct fscrypt_inode_info *ci, 699 const struct fscrypt_master_key *mk); 700 701 void fscrypt_hash_inode_number(struct fscrypt_inode_info *ci, 702 const struct fscrypt_master_key *mk); 703 704 int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported); 705 706 /** 707 * fscrypt_require_key() - require an inode's encryption key 708 * @inode: the inode we need the key for 709 * 710 * If the inode is encrypted, set up its encryption key if not already done. 711 * Then require that the key be present and return -ENOKEY otherwise. 712 * 713 * No locks are needed, and the key will live as long as the struct inode --- so 714 * it won't go away from under you. 715 * 716 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code 717 * if a problem occurred while setting up the encryption key. 718 */ 719 static inline int fscrypt_require_key(struct inode *inode) 720 { 721 if (IS_ENCRYPTED(inode)) { 722 int err = fscrypt_get_encryption_info(inode, false); 723 724 if (err) 725 return err; 726 if (!fscrypt_has_encryption_key(inode)) 727 return -ENOKEY; 728 } 729 return 0; 730 } 731 732 /* keysetup_v1.c */ 733 734 void fscrypt_put_direct_key(struct fscrypt_direct_key *dk); 735 736 int fscrypt_setup_v1_file_key(struct fscrypt_inode_info *ci, 737 const u8 *raw_master_key); 738 739 int fscrypt_setup_v1_file_key_via_subscribed_keyrings( 740 struct fscrypt_inode_info *ci); 741 742 /* policy.c */ 743 744 bool fscrypt_policies_equal(const union fscrypt_policy *policy1, 745 const union fscrypt_policy *policy2); 746 int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, 747 struct fscrypt_key_specifier *key_spec); 748 const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb); 749 bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, 750 const struct inode *inode); 751 int fscrypt_policy_from_context(union fscrypt_policy *policy_u, 752 const union fscrypt_context *ctx_u, 753 int ctx_size); 754 const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir); 755 756 #endif /* _FSCRYPT_PRIVATE_H */ 757