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__ */
544
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