fs/ubifs/key.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * This file is part of UBIFS.
   4  *
   5  * Copyright (C) 2006-2008 Nokia Corporation.
   6  *
   7  * Authors: Artem Bityutskiy (Битюцкий Артём)
   8  *          Adrian Hunter
   9  */
  10
  11 /*
  12  * This header contains various key-related definitions and helper function.
  13  * UBIFS allows several key schemes, so we access key fields only via these
  14  * helpers. At the moment only one key scheme is supported.
  15  *
  16  * Simple key scheme
  17  * ~~~~~~~~~~~~~~~~~
  18  *
  19  * Keys are 64-bits long. First 32-bits are inode number (parent inode number
  20  * in case of direntry key). Next 3 bits are node type. The last 29 bits are
  21  * 4KiB offset in case of inode node, and direntry hash in case of a direntry
  22  * node. We use "r5" hash borrowed from reiserfs.
  23  */
  24
  25 /*
  26  * Lot's of the key helpers require a struct ubifs_info *c as the first parameter.
  27  * But we are not using it at all currently. That's designed for future extensions of
  28  * different c->key_format. But right now, there is only one key type, UBIFS_SIMPLE_KEY_FMT.
  29  */
  30
  31 #ifndef __UBIFS_KEY_H__
  32 #define __UBIFS_KEY_H__
  33
  34 /**
  35  * key_mask_hash - mask a valid hash value.
  36  * @val: value to be masked
  37  *
  38  * We use hash values as offset in directories, so values %0 and %1 are
  39  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
  40  * function makes sure the reserved values are not used.
  41  */
  42 static inline uint32_t key_mask_hash(uint32_t hash)
  43 {
  44         hash &= UBIFS_S_KEY_HASH_MASK;
  45         if (unlikely(hash <= 2))
  46                 hash += 3;
  47         return hash;
  48 }
  49
  50 /**
  51  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  52  * @s: direntry name
  53  * @len: name length
  54  */
  55 static inline uint32_t key_r5_hash(const char *s, int len)
  56 {
  57         uint32_t a = 0;
  58         const signed char *str = (const signed char *)s;
  59
  60         while (len--) {
  61                 a += *str << 4;
  62                 a += *str >> 4;
  63                 a *= 11;
  64                 str++;
  65         }
  66
  67         return key_mask_hash(a);
  68 }
  69
  70 /**
  71  * key_test_hash - testing hash function.
  72  * @str: direntry name
  73  * @len: name length
  74  */
  75 static inline uint32_t key_test_hash(const char *str, int len)
  76 {
  77         uint32_t a = 0;
  78
  79         len = min_t(uint32_t, len, 4);
  80         memcpy(&a, str, len);
  81         return key_mask_hash(a);
  82 }
  83
  84 /**
  85  * ino_key_init - initialize inode key.
  86  * @c: UBIFS file-system description object
  87  * @key: key to initialize
  88  * @inum: inode number
  89  */
  90 static inline void ino_key_init(const struct ubifs_info *c,
  91                                 union ubifs_key *key, ino_t inum)
  92 {
  93         key->u32[0] = inum;
  94         key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
  95 }
  96
  97 /**
  98  * ino_key_init_flash - initialize on-flash inode key.
  99  * @c: UBIFS file-system description object
 100  * @k: key to initialize
 101  * @inum: inode number
 102  */
 103 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
 104                                       ino_t inum)
 105 {
 106         union ubifs_key *key = k;
 107
 108         key->j32[0] = cpu_to_le32(inum);
 109         key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
 110         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 111 }
 112
 113 /**
 114  * lowest_ino_key - get the lowest possible inode key.
 115  * @c: UBIFS file-system description object
 116  * @key: key to initialize
 117  * @inum: inode number
 118  */
 119 static inline void lowest_ino_key(const struct ubifs_info *c,
 120                                 union ubifs_key *key, ino_t inum)
 121 {
 122         key->u32[0] = inum;
 123         key->u32[1] = 0;
 124 }
 125
 126 /**
 127  * highest_ino_key - get the highest possible inode key.
 128  * @c: UBIFS file-system description object
 129  * @key: key to initialize
 130  * @inum: inode number
 131  */
 132 static inline void highest_ino_key(const struct ubifs_info *c,
 133                                 union ubifs_key *key, ino_t inum)
 134 {
 135         key->u32[0] = inum;
 136         key->u32[1] = 0xffffffff;
 137 }
 138
 139 /**
 140  * dent_key_init - initialize directory entry key.
 141  * @c: UBIFS file-system description object
 142  * @key: key to initialize
 143  * @inum: parent inode number
 144  * @nm: direntry name and length. Not a string when encrypted!
 145  */
 146 static inline void dent_key_init(const struct ubifs_info *c,
 147                                  union ubifs_key *key, ino_t inum,
 148                                  const struct fscrypt_name *nm)
 149 {
 150         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 151
 152         ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
 153         key->u32[0] = inum;
 154         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 155 }
 156
 157 /**
 158  * dent_key_init_hash - initialize directory entry key without re-calculating
 159  *                      hash function.
 160  * @c: UBIFS file-system description object
 161  * @key: key to initialize
 162  * @inum: parent inode number
 163  * @hash: direntry name hash
 164  */
 165 static inline void dent_key_init_hash(const struct ubifs_info *c,
 166                                       union ubifs_key *key, ino_t inum,
 167                                       uint32_t hash)
 168 {
 169         ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
 170         key->u32[0] = inum;
 171         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 172 }
 173
 174 /**
 175  * dent_key_init_flash - initialize on-flash directory entry key.
 176  * @c: UBIFS file-system description object
 177  * @k: key to initialize
 178  * @inum: parent inode number
 179  * @nm: direntry name and length
 180  */
 181 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
 182                                        ino_t inum,
 183                                        const struct fscrypt_name *nm)
 184 {
 185         union ubifs_key *key = k;
 186         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 187
 188         ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
 189         key->j32[0] = cpu_to_le32(inum);
 190         key->j32[1] = cpu_to_le32(hash |
 191                                   (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
 192         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 193 }
 194
 195 /**
 196  * lowest_dent_key - get the lowest possible directory entry key.
 197  * @c: UBIFS file-system description object
 198  * @key: where to store the lowest key
 199  * @inum: parent inode number
 200  */
 201 static inline void lowest_dent_key(const struct ubifs_info *c,
 202                                    union ubifs_key *key, ino_t inum)
 203 {
 204         key->u32[0] = inum;
 205         key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
 206 }
 207
 208 /**
 209  * xent_key_init - initialize extended attribute entry key.
 210  * @c: UBIFS file-system description object
 211  * @key: key to initialize
 212  * @inum: host inode number
 213  * @nm: extended attribute entry name and length
 214  */
 215 static inline void xent_key_init(const struct ubifs_info *c,
 216                                  union ubifs_key *key, ino_t inum,
 217                                  const struct fscrypt_name *nm)
 218 {
 219         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 220
 221         ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
 222         key->u32[0] = inum;
 223         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 224 }
 225
 226 /**
 227  * xent_key_init_flash - initialize on-flash extended attribute entry key.
 228  * @c: UBIFS file-system description object
 229  * @k: key to initialize
 230  * @inum: host inode number
 231  * @nm: extended attribute entry name and length
 232  */
 233 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 234                                        ino_t inum, const struct fscrypt_name *nm)
 235 {
 236         union ubifs_key *key = k;
 237         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 238
 239         ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
 240         key->j32[0] = cpu_to_le32(inum);
 241         key->j32[1] = cpu_to_le32(hash |
 242                                   (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 243         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 244 }
 245
 246 /**
 247  * lowest_xent_key - get the lowest possible extended attribute entry key.
 248  * @c: UBIFS file-system description object
 249  * @key: where to store the lowest key
 250  * @inum: host inode number
 251  */
 252 static inline void lowest_xent_key(const struct ubifs_info *c,
 253                                    union ubifs_key *key, ino_t inum)
 254 {
 255         key->u32[0] = inum;
 256         key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 257 }
 258
 259 /**
 260  * data_key_init - initialize data key.
 261  * @c: UBIFS file-system description object
 262  * @key: key to initialize
 263  * @inum: inode number
 264  * @block: block number
 265  */
 266 static inline void data_key_init(const struct ubifs_info *c,
 267                                  union ubifs_key *key, ino_t inum,
 268                                  unsigned int block)
 269 {
 270         ubifs_assert(c, !(block & ~UBIFS_S_KEY_BLOCK_MASK));
 271         key->u32[0] = inum;
 272         key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 273 }
 274
 275 /**
 276  * highest_data_key - get the highest possible data key for an inode.
 277  * @c: UBIFS file-system description object
 278  * @key: key to initialize
 279  * @inum: inode number
 280  */
 281 static inline void highest_data_key(const struct ubifs_info *c,
 282                                    union ubifs_key *key, ino_t inum)
 283 {
 284         data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
 285 }
 286
 287 /**
 288  * trun_key_init - initialize truncation node key.
 289  * @c: UBIFS file-system description object
 290  * @key: key to initialize
 291  * @inum: inode number
 292  *
 293  * Note, UBIFS does not have truncation keys on the media and this function is
 294  * only used for purposes of replay.
 295  */
 296 static inline void trun_key_init(const struct ubifs_info *c,
 297                                  union ubifs_key *key, ino_t inum)
 298 {
 299         key->u32[0] = inum;
 300         key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 301 }
 302
 303 /**
 304  * invalid_key_init - initialize invalid node key.
 305  * @c: UBIFS file-system description object
 306  * @key: key to initialize
 307  *
 308  * This is a helper function which marks a @key object as invalid.
 309  */
 310 static inline void invalid_key_init(const struct ubifs_info *c,
 311                                     union ubifs_key *key)
 312 {
 313         key->u32[0] = 0xDEADBEAF;
 314         key->u32[1] = UBIFS_INVALID_KEY;
 315 }
 316
 317 /**
 318  * key_type - get key type.
 319  * @c: UBIFS file-system description object
 320  * @key: key to get type of
 321  */
 322 static inline int key_type(const struct ubifs_info *c,
 323                            const union ubifs_key *key)
 324 {
 325         return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 326 }
 327
 328 /**
 329  * key_type_flash - get type of a on-flash formatted key.
 330  * @c: UBIFS file-system description object
 331  * @k: key to get type of
 332  */
 333 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
 334 {
 335         const union ubifs_key *key = k;
 336
 337         return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 338 }
 339
 340 /**
 341  * key_inum - fetch inode number from key.
 342  * @c: UBIFS file-system description object
 343  * @k: key to fetch inode number from
 344  */
 345 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 346 {
 347         const union ubifs_key *key = k;
 348
 349         return key->u32[0];
 350 }
 351
 352 /**
 353  * key_inum_flash - fetch inode number from an on-flash formatted key.
 354  * @c: UBIFS file-system description object
 355  * @k: key to fetch inode number from
 356  */
 357 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 358 {
 359         const union ubifs_key *key = k;
 360
 361         return le32_to_cpu(key->j32[0]);
 362 }
 363
 364 /**
 365  * key_hash - get directory entry hash.
 366  * @c: UBIFS file-system description object
 367  * @key: the key to get hash from
 368  */
 369 static inline uint32_t key_hash(const struct ubifs_info *c,
 370                                 const union ubifs_key *key)
 371 {
 372         return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 373 }
 374
 375 /**
 376  * key_hash_flash - get directory entry hash from an on-flash formatted key.
 377  * @c: UBIFS file-system description object
 378  * @k: the key to get hash from
 379  */
 380 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 381 {
 382         const union ubifs_key *key = k;
 383
 384         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 385 }
 386
 387 /**
 388  * key_block - get data block number.
 389  * @c: UBIFS file-system description object
 390  * @key: the key to get the block number from
 391  */
 392 static inline unsigned int key_block(const struct ubifs_info *c,
 393                                      const union ubifs_key *key)
 394 {
 395         return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 396 }
 397
 398 /**
 399  * key_block_flash - get data block number from an on-flash formatted key.
 400  * @c: UBIFS file-system description object
 401  * @k: the key to get the block number from
 402  */
 403 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 404                                            const void *k)
 405 {
 406         const union ubifs_key *key = k;
 407
 408         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 409 }
 410
 411 /**
 412  * key_read - transform a key to in-memory format.
 413  * @c: UBIFS file-system description object
 414  * @from: the key to transform
 415  * @to: the key to store the result
 416  */
 417 static inline void key_read(const struct ubifs_info *c, const void *from,
 418                             union ubifs_key *to)
 419 {
 420         const union ubifs_key *f = from;
 421
 422         to->u32[0] = le32_to_cpu(f->j32[0]);
 423         to->u32[1] = le32_to_cpu(f->j32[1]);
 424 }
 425
 426 /**
 427  * key_write - transform a key from in-memory format.
 428  * @c: UBIFS file-system description object
 429  * @from: the key to transform
 430  * @to: the key to store the result
 431  */
 432 static inline void key_write(const struct ubifs_info *c,
 433                              const union ubifs_key *from, void *to)
 434 {
 435         union ubifs_key *t = to;
 436
 437         t->j32[0] = cpu_to_le32(from->u32[0]);
 438         t->j32[1] = cpu_to_le32(from->u32[1]);
 439         memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 440 }
 441
 442 /**
 443  * key_write_idx - transform a key from in-memory format for the index.
 444  * @c: UBIFS file-system description object
 445  * @from: the key to transform
 446  * @to: the key to store the result
 447  */
 448 static inline void key_write_idx(const struct ubifs_info *c,
 449                                  const union ubifs_key *from, void *to)
 450 {
 451         union ubifs_key *t = to;
 452
 453         t->j32[0] = cpu_to_le32(from->u32[0]);
 454         t->j32[1] = cpu_to_le32(from->u32[1]);
 455 }
 456
 457 /**
 458  * key_copy - copy a key.
 459  * @c: UBIFS file-system description object
 460  * @from: the key to copy from
 461  * @to: the key to copy to
 462  */
 463 static inline void key_copy(const struct ubifs_info *c,
 464                             const union ubifs_key *from, union ubifs_key *to)
 465 {
 466         to->u64[0] = from->u64[0];
 467 }
 468
 469 /**
 470  * keys_cmp - compare keys.
 471  * @c: UBIFS file-system description object
 472  * @key1: the first key to compare
 473  * @key2: the second key to compare
 474  *
 475  * This function compares 2 keys and returns %-1 if @key1 is less than
 476  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
 477  */
 478 static inline int keys_cmp(const struct ubifs_info *c,
 479                            const union ubifs_key *key1,
 480                            const union ubifs_key *key2)
 481 {
 482         if (key1->u32[0] < key2->u32[0])
 483                 return -1;
 484         if (key1->u32[0] > key2->u32[0])
 485                 return 1;
 486         if (key1->u32[1] < key2->u32[1])
 487                 return -1;
 488         if (key1->u32[1] > key2->u32[1])
 489                 return 1;
 490
 491         return 0;
 492 }
 493
 494 /**
 495  * keys_eq - determine if keys are equivalent.
 496  * @c: UBIFS file-system description object
 497  * @key1: the first key to compare
 498  * @key2: the second key to compare
 499  *
 500  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
 501  * %0 if not.
 502  */
 503 static inline int keys_eq(const struct ubifs_info *c,
 504                           const union ubifs_key *key1,
 505                           const union ubifs_key *key2)
 506 {
 507         if (key1->u32[0] != key2->u32[0])
 508                 return 0;
 509         if (key1->u32[1] != key2->u32[1])
 510                 return 0;
 511         return 1;
 512 }
 513
 514 /**
 515  * is_hash_key - is a key vulnerable to hash collisions.
 516  * @c: UBIFS file-system description object
 517  * @key: key
 518  *
 519  * This function returns %1 if @key is a hashed key or %0 otherwise.
 520  */
 521 static inline int is_hash_key(const struct ubifs_info *c,
 522                               const union ubifs_key *key)
 523 {
 524         int type = key_type(c, key);
 525
 526         return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 527 }
 528
 529 /**
 530  * key_max_inode_size - get maximum file size allowed by current key format.
 531  * @c: UBIFS file-system description object
 532  */
 533 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 534 {
 535         switch (c->key_fmt) {
 536         case UBIFS_SIMPLE_KEY_FMT:
 537                 return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 538         default:
 539                 return 0;
 540         }
 541 }
 542
 543 #endif /* !__UBIFS_KEY_H__ */