fs/ubifs/key.h

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  * Authors: Artem Bityutskiy (Битюцкий Артём)
  20  *          Adrian Hunter
  21  */
  22
  23 /*
  24  * This header contains various key-related definitions and helper function.
  25  * UBIFS allows several key schemes, so we access key fields only via these
  26  * helpers. At the moment only one key scheme is supported.
  27  *
  28  * Simple key scheme
  29  * ~~~~~~~~~~~~~~~~~
  30  *
  31  * Keys are 64-bits long. First 32-bits are inode number (parent inode number
  32  * in case of direntry key). Next 3 bits are node type. The last 29 bits are
  33  * 4KiB offset in case of inode node, and direntry hash in case of a direntry
  34  * node. We use "r5" hash borrowed from reiserfs.
  35  */
  36
  37 /*
  38  * Lot's of the key helpers require a struct ubifs_info *c as the first parameter.
  39  * But we are not using it at all currently. That's designed for future extensions of
  40  * different c->key_format. But right now, there is only one key type, UBIFS_SIMPLE_KEY_FMT.
  41  */
  42
  43 #ifndef __UBIFS_KEY_H__
  44 #define __UBIFS_KEY_H__
  45
  46 /**
  47  * key_mask_hash - mask a valid hash value.
  48  * @val: value to be masked
  49  *
  50  * We use hash values as offset in directories, so values %0 and %1 are
  51  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
  52  * function makes sure the reserved values are not used.
  53  */
  54 static inline uint32_t key_mask_hash(uint32_t hash)
  55 {
  56         hash &= UBIFS_S_KEY_HASH_MASK;
  57         if (unlikely(hash <= 2))
  58                 hash += 3;
  59         return hash;
  60 }
  61
  62 /**
  63  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  64  * @s: direntry name
  65  * @len: name length
  66  */
  67 static inline uint32_t key_r5_hash(const char *s, int len)
  68 {
  69         uint32_t a = 0;
  70         const signed char *str = (const signed char *)s;
  71
  72         while (len--) {
  73                 a += *str << 4;
  74                 a += *str >> 4;
  75                 a *= 11;
  76                 str++;
  77         }
  78
  79         return key_mask_hash(a);
  80 }
  81
  82 /**
  83  * key_test_hash - testing hash function.
  84  * @str: direntry name
  85  * @len: name length
  86  */
  87 static inline uint32_t key_test_hash(const char *str, int len)
  88 {
  89         uint32_t a = 0;
  90
  91         len = min_t(uint32_t, len, 4);
  92         memcpy(&a, str, len);
  93         return key_mask_hash(a);
  94 }
  95
  96 /**
  97  * ino_key_init - initialize inode key.
  98  * @c: UBIFS file-system description object
  99  * @key: key to initialize
 100  * @inum: inode number
 101  */
 102 static inline void ino_key_init(const struct ubifs_info *c,
 103                                 union ubifs_key *key, ino_t inum)
 104 {
 105         key->u32[0] = inum;
 106         key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
 107 }
 108
 109 /**
 110  * ino_key_init_flash - initialize on-flash inode key.
 111  * @c: UBIFS file-system description object
 112  * @k: key to initialize
 113  * @inum: inode number
 114  */
 115 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
 116                                       ino_t inum)
 117 {
 118         union ubifs_key *key = k;
 119
 120         key->j32[0] = cpu_to_le32(inum);
 121         key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
 122         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 123 }
 124
 125 /**
 126  * lowest_ino_key - get the lowest possible inode key.
 127  * @c: UBIFS file-system description object
 128  * @key: key to initialize
 129  * @inum: inode number
 130  */
 131 static inline void lowest_ino_key(const struct ubifs_info *c,
 132                                 union ubifs_key *key, ino_t inum)
 133 {
 134         key->u32[0] = inum;
 135         key->u32[1] = 0;
 136 }
 137
 138 /**
 139  * highest_ino_key - get the highest possible inode key.
 140  * @c: UBIFS file-system description object
 141  * @key: key to initialize
 142  * @inum: inode number
 143  */
 144 static inline void highest_ino_key(const struct ubifs_info *c,
 145                                 union ubifs_key *key, ino_t inum)
 146 {
 147         key->u32[0] = inum;
 148         key->u32[1] = 0xffffffff;
 149 }
 150
 151 /**
 152  * dent_key_init - initialize directory entry key.
 153  * @c: UBIFS file-system description object
 154  * @key: key to initialize
 155  * @inum: parent inode number
 156  * @nm: direntry name and length. Not a string when encrypted!
 157  */
 158 static inline void dent_key_init(const struct ubifs_info *c,
 159                                  union ubifs_key *key, ino_t inum,
 160                                  const struct fscrypt_name *nm)
 161 {
 162         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 163
 164         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 165         key->u32[0] = inum;
 166         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 167 }
 168
 169 /**
 170  * dent_key_init_hash - initialize directory entry key without re-calculating
 171  *                      hash function.
 172  * @c: UBIFS file-system description object
 173  * @key: key to initialize
 174  * @inum: parent inode number
 175  * @hash: direntry name hash
 176  */
 177 static inline void dent_key_init_hash(const struct ubifs_info *c,
 178                                       union ubifs_key *key, ino_t inum,
 179                                       uint32_t hash)
 180 {
 181         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 182         key->u32[0] = inum;
 183         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 184 }
 185
 186 /**
 187  * dent_key_init_flash - initialize on-flash directory entry key.
 188  * @c: UBIFS file-system description object
 189  * @k: key to initialize
 190  * @inum: parent inode number
 191  * @nm: direntry name and length
 192  */
 193 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
 194                                        ino_t inum,
 195                                        const struct fscrypt_name *nm)
 196 {
 197         union ubifs_key *key = k;
 198         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 199
 200         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 201         key->j32[0] = cpu_to_le32(inum);
 202         key->j32[1] = cpu_to_le32(hash |
 203                                   (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
 204         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 205 }
 206
 207 /**
 208  * lowest_dent_key - get the lowest possible directory entry key.
 209  * @c: UBIFS file-system description object
 210  * @key: where to store the lowest key
 211  * @inum: parent inode number
 212  */
 213 static inline void lowest_dent_key(const struct ubifs_info *c,
 214                                    union ubifs_key *key, ino_t inum)
 215 {
 216         key->u32[0] = inum;
 217         key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
 218 }
 219
 220 /**
 221  * xent_key_init - initialize extended attribute entry key.
 222  * @c: UBIFS file-system description object
 223  * @key: key to initialize
 224  * @inum: host inode number
 225  * @nm: extended attribute entry name and length
 226  */
 227 static inline void xent_key_init(const struct ubifs_info *c,
 228                                  union ubifs_key *key, ino_t inum,
 229                                  const struct fscrypt_name *nm)
 230 {
 231         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 232
 233         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 234         key->u32[0] = inum;
 235         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 236 }
 237
 238 /**
 239  * xent_key_init_flash - initialize on-flash extended attribute entry key.
 240  * @c: UBIFS file-system description object
 241  * @k: key to initialize
 242  * @inum: host inode number
 243  * @nm: extended attribute entry name and length
 244  */
 245 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 246                                        ino_t inum, const struct fscrypt_name *nm)
 247 {
 248         union ubifs_key *key = k;
 249         uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
 250
 251         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 252         key->j32[0] = cpu_to_le32(inum);
 253         key->j32[1] = cpu_to_le32(hash |
 254                                   (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 255         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 256 }
 257
 258 /**
 259  * lowest_xent_key - get the lowest possible extended attribute entry key.
 260  * @c: UBIFS file-system description object
 261  * @key: where to store the lowest key
 262  * @inum: host inode number
 263  */
 264 static inline void lowest_xent_key(const struct ubifs_info *c,
 265                                    union ubifs_key *key, ino_t inum)
 266 {
 267         key->u32[0] = inum;
 268         key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 269 }
 270
 271 /**
 272  * data_key_init - initialize data key.
 273  * @c: UBIFS file-system description object
 274  * @key: key to initialize
 275  * @inum: inode number
 276  * @block: block number
 277  */
 278 static inline void data_key_init(const struct ubifs_info *c,
 279                                  union ubifs_key *key, ino_t inum,
 280                                  unsigned int block)
 281 {
 282         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 283         key->u32[0] = inum;
 284         key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 285 }
 286
 287 /**
 288  * highest_data_key - get the highest possible data key for an inode.
 289  * @c: UBIFS file-system description object
 290  * @key: key to initialize
 291  * @inum: inode number
 292  */
 293 static inline void highest_data_key(const struct ubifs_info *c,
 294                                    union ubifs_key *key, ino_t inum)
 295 {
 296         data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
 297 }
 298
 299 /**
 300  * trun_key_init - initialize truncation node key.
 301  * @c: UBIFS file-system description object
 302  * @key: key to initialize
 303  * @inum: inode number
 304  *
 305  * Note, UBIFS does not have truncation keys on the media and this function is
 306  * only used for purposes of replay.
 307  */
 308 static inline void trun_key_init(const struct ubifs_info *c,
 309                                  union ubifs_key *key, ino_t inum)
 310 {
 311         key->u32[0] = inum;
 312         key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 313 }
 314
 315 /**
 316  * invalid_key_init - initialize invalid node key.
 317  * @c: UBIFS file-system description object
 318  * @key: key to initialize
 319  *
 320  * This is a helper function which marks a @key object as invalid.
 321  */
 322 static inline void invalid_key_init(const struct ubifs_info *c,
 323                                     union ubifs_key *key)
 324 {
 325         key->u32[0] = 0xDEADBEAF;
 326         key->u32[1] = UBIFS_INVALID_KEY;
 327 }
 328
 329 /**
 330  * key_type - get key type.
 331  * @c: UBIFS file-system description object
 332  * @key: key to get type of
 333  */
 334 static inline int key_type(const struct ubifs_info *c,
 335                            const union ubifs_key *key)
 336 {
 337         return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 338 }
 339
 340 /**
 341  * key_type_flash - get type of a on-flash formatted key.
 342  * @c: UBIFS file-system description object
 343  * @k: key to get type of
 344  */
 345 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
 346 {
 347         const union ubifs_key *key = k;
 348
 349         return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 350 }
 351
 352 /**
 353  * key_inum - fetch inode number from key.
 354  * @c: UBIFS file-system description object
 355  * @k: key to fetch inode number from
 356  */
 357 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 358 {
 359         const union ubifs_key *key = k;
 360
 361         return key->u32[0];
 362 }
 363
 364 /**
 365  * key_inum_flash - fetch inode number from an on-flash formatted key.
 366  * @c: UBIFS file-system description object
 367  * @k: key to fetch inode number from
 368  */
 369 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 370 {
 371         const union ubifs_key *key = k;
 372
 373         return le32_to_cpu(key->j32[0]);
 374 }
 375
 376 /**
 377  * key_hash - get directory entry hash.
 378  * @c: UBIFS file-system description object
 379  * @key: the key to get hash from
 380  */
 381 static inline uint32_t key_hash(const struct ubifs_info *c,
 382                                 const union ubifs_key *key)
 383 {
 384         return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 385 }
 386
 387 /**
 388  * key_hash_flash - get directory entry hash from an on-flash formatted key.
 389  * @c: UBIFS file-system description object
 390  * @k: the key to get hash from
 391  */
 392 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 393 {
 394         const union ubifs_key *key = k;
 395
 396         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 397 }
 398
 399 /**
 400  * key_block - get data block number.
 401  * @c: UBIFS file-system description object
 402  * @key: the key to get the block number from
 403  */
 404 static inline unsigned int key_block(const struct ubifs_info *c,
 405                                      const union ubifs_key *key)
 406 {
 407         return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 408 }
 409
 410 /**
 411  * key_block_flash - get data block number from an on-flash formatted key.
 412  * @c: UBIFS file-system description object
 413  * @k: the key to get the block number from
 414  */
 415 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 416                                            const void *k)
 417 {
 418         const union ubifs_key *key = k;
 419
 420         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 421 }
 422
 423 /**
 424  * key_read - transform a key to in-memory format.
 425  * @c: UBIFS file-system description object
 426  * @from: the key to transform
 427  * @to: the key to store the result
 428  */
 429 static inline void key_read(const struct ubifs_info *c, const void *from,
 430                             union ubifs_key *to)
 431 {
 432         const union ubifs_key *f = from;
 433
 434         to->u32[0] = le32_to_cpu(f->j32[0]);
 435         to->u32[1] = le32_to_cpu(f->j32[1]);
 436 }
 437
 438 /**
 439  * key_write - transform a key from in-memory format.
 440  * @c: UBIFS file-system description object
 441  * @from: the key to transform
 442  * @to: the key to store the result
 443  */
 444 static inline void key_write(const struct ubifs_info *c,
 445                              const union ubifs_key *from, void *to)
 446 {
 447         union ubifs_key *t = to;
 448
 449         t->j32[0] = cpu_to_le32(from->u32[0]);
 450         t->j32[1] = cpu_to_le32(from->u32[1]);
 451         memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 452 }
 453
 454 /**
 455  * key_write_idx - transform a key from in-memory format for the index.
 456  * @c: UBIFS file-system description object
 457  * @from: the key to transform
 458  * @to: the key to store the result
 459  */
 460 static inline void key_write_idx(const struct ubifs_info *c,
 461                                  const union ubifs_key *from, void *to)
 462 {
 463         union ubifs_key *t = to;
 464
 465         t->j32[0] = cpu_to_le32(from->u32[0]);
 466         t->j32[1] = cpu_to_le32(from->u32[1]);
 467 }
 468
 469 /**
 470  * key_copy - copy a key.
 471  * @c: UBIFS file-system description object
 472  * @from: the key to copy from
 473  * @to: the key to copy to
 474  */
 475 static inline void key_copy(const struct ubifs_info *c,
 476                             const union ubifs_key *from, union ubifs_key *to)
 477 {
 478         to->u64[0] = from->u64[0];
 479 }
 480
 481 /**
 482  * keys_cmp - compare keys.
 483  * @c: UBIFS file-system description object
 484  * @key1: the first key to compare
 485  * @key2: the second key to compare
 486  *
 487  * This function compares 2 keys and returns %-1 if @key1 is less than
 488  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
 489  */
 490 static inline int keys_cmp(const struct ubifs_info *c,
 491                            const union ubifs_key *key1,
 492                            const union ubifs_key *key2)
 493 {
 494         if (key1->u32[0] < key2->u32[0])
 495                 return -1;
 496         if (key1->u32[0] > key2->u32[0])
 497                 return 1;
 498         if (key1->u32[1] < key2->u32[1])
 499                 return -1;
 500         if (key1->u32[1] > key2->u32[1])
 501                 return 1;
 502
 503         return 0;
 504 }
 505
 506 /**
 507  * keys_eq - determine if keys are equivalent.
 508  * @c: UBIFS file-system description object
 509  * @key1: the first key to compare
 510  * @key2: the second key to compare
 511  *
 512  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
 513  * %0 if not.
 514  */
 515 static inline int keys_eq(const struct ubifs_info *c,
 516                           const union ubifs_key *key1,
 517                           const union ubifs_key *key2)
 518 {
 519         if (key1->u32[0] != key2->u32[0])
 520                 return 0;
 521         if (key1->u32[1] != key2->u32[1])
 522                 return 0;
 523         return 1;
 524 }
 525
 526 /**
 527  * is_hash_key - is a key vulnerable to hash collisions.
 528  * @c: UBIFS file-system description object
 529  * @key: key
 530  *
 531  * This function returns %1 if @key is a hashed key or %0 otherwise.
 532  */
 533 static inline int is_hash_key(const struct ubifs_info *c,
 534                               const union ubifs_key *key)
 535 {
 536         int type = key_type(c, key);
 537
 538         return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 539 }
 540
 541 /**
 542  * key_max_inode_size - get maximum file size allowed by current key format.
 543  * @c: UBIFS file-system description object
 544  */
 545 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 546 {
 547         switch (c->key_fmt) {
 548         case UBIFS_SIMPLE_KEY_FMT:
 549                 return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 550         default:
 551                 return 0;
 552         }
 553 }
 554
 555 #endif /* !__UBIFS_KEY_H__ */