xref: /linux/fs/ubifs/key.h (revision 367b8112fe2ea5c39a7bb4d263dcdd9b612fae18) 
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 #ifndef __UBIFS_KEY_H__
38 #define __UBIFS_KEY_H__
39 
40 /**
41  * key_r5_hash - R5 hash function (borrowed from reiserfs).
42  * @s: direntry name
43  * @len: name length
44  */
45 static inline uint32_t key_r5_hash(const char *s, int len)
46 {
47 	uint32_t a = 0;
48 	const signed char *str = (const signed char *)s;
49 
50 	while (*str) {
51 		a += *str << 4;
52 		a += *str >> 4;
53 		a *= 11;
54 		str++;
55 	}
56 
57 	a &= UBIFS_S_KEY_HASH_MASK;
58 
59 	/*
60 	 * We use hash values as offset in directories, so values %0 and %1 are
61 	 * reserved for "." and "..". %2 is reserved for "end of readdir"
62 	 * marker.
63 	 */
64 	if (unlikely(a >= 0 && a <= 2))
65 		a += 3;
66 	return a;
67 }
68 
69 /**
70  * key_test_hash - testing hash function.
71  * @str: direntry name
72  * @len: name length
73  */
74 static inline uint32_t key_test_hash(const char *str, int len)
75 {
76 	uint32_t a = 0;
77 
78 	len = min_t(uint32_t, len, 4);
79 	memcpy(&a, str, len);
80 	a &= UBIFS_S_KEY_HASH_MASK;
81 	if (unlikely(a >= 0 && a <= 2))
82 		a += 3;
83 	return a;
84 }
85 
86 /**
87  * ino_key_init - initialize inode key.
88  * @c: UBIFS file-system description object
89  * @key: key to initialize
90  * @inum: inode number
91  */
92 static inline void ino_key_init(const struct ubifs_info *c,
93 				union ubifs_key *key, ino_t inum)
94 {
95 	key->u32[0] = inum;
96 	key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
97 }
98 
99 /**
100  * ino_key_init_flash - initialize on-flash inode key.
101  * @c: UBIFS file-system description object
102  * @k: key to initialize
103  * @inum: inode number
104  */
105 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
106 				      ino_t inum)
107 {
108 	union ubifs_key *key = k;
109 
110 	key->j32[0] = cpu_to_le32(inum);
111 	key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
112 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
113 }
114 
115 /**
116  * lowest_ino_key - get the lowest possible inode key.
117  * @c: UBIFS file-system description object
118  * @key: key to initialize
119  * @inum: inode number
120  */
121 static inline void lowest_ino_key(const struct ubifs_info *c,
122 				union ubifs_key *key, ino_t inum)
123 {
124 	key->u32[0] = inum;
125 	key->u32[1] = 0;
126 }
127 
128 /**
129  * highest_ino_key - get the highest possible inode key.
130  * @c: UBIFS file-system description object
131  * @key: key to initialize
132  * @inum: inode number
133  */
134 static inline void highest_ino_key(const struct ubifs_info *c,
135 				union ubifs_key *key, ino_t inum)
136 {
137 	key->u32[0] = inum;
138 	key->u32[1] = 0xffffffff;
139 }
140 
141 /**
142  * dent_key_init - initialize directory entry key.
143  * @c: UBIFS file-system description object
144  * @key: key to initialize
145  * @inum: parent inode number
146  * @nm: direntry name and length
147  */
148 static inline void dent_key_init(const struct ubifs_info *c,
149 				 union ubifs_key *key, ino_t inum,
150 				 const struct qstr *nm)
151 {
152 	uint32_t hash = c->key_hash(nm->name, nm->len);
153 
154 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
155 	key->u32[0] = inum;
156 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
157 }
158 
159 /**
160  * dent_key_init_hash - initialize directory entry key without re-calculating
161  *                      hash function.
162  * @c: UBIFS file-system description object
163  * @key: key to initialize
164  * @inum: parent inode number
165  * @hash: direntry name hash
166  */
167 static inline void dent_key_init_hash(const struct ubifs_info *c,
168 				      union ubifs_key *key, ino_t inum,
169 				      uint32_t hash)
170 {
171 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
172 	key->u32[0] = inum;
173 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
174 }
175 
176 /**
177  * dent_key_init_flash - initialize on-flash directory entry key.
178  * @c: UBIFS file-system description object
179  * @k: key to initialize
180  * @inum: parent inode number
181  * @nm: direntry name and length
182  */
183 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
184 				       ino_t inum, const struct qstr *nm)
185 {
186 	union ubifs_key *key = k;
187 	uint32_t hash = c->key_hash(nm->name, nm->len);
188 
189 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
190 	key->j32[0] = cpu_to_le32(inum);
191 	key->j32[1] = cpu_to_le32(hash |
192 				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
193 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
194 }
195 
196 /**
197  * lowest_dent_key - get the lowest possible directory entry key.
198  * @c: UBIFS file-system description object
199  * @key: where to store the lowest key
200  * @inum: parent inode number
201  */
202 static inline void lowest_dent_key(const struct ubifs_info *c,
203 				   union ubifs_key *key, ino_t inum)
204 {
205 	key->u32[0] = inum;
206 	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
207 }
208 
209 /**
210  * xent_key_init - initialize extended attribute entry key.
211  * @c: UBIFS file-system description object
212  * @key: key to initialize
213  * @inum: host inode number
214  * @nm: extended attribute entry name and length
215  */
216 static inline void xent_key_init(const struct ubifs_info *c,
217 				 union ubifs_key *key, ino_t inum,
218 				 const struct qstr *nm)
219 {
220 	uint32_t hash = c->key_hash(nm->name, nm->len);
221 
222 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
223 	key->u32[0] = inum;
224 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
225 }
226 
227 /**
228  * xent_key_init_hash - initialize extended attribute entry key without
229  *                      re-calculating hash function.
230  * @c: UBIFS file-system description object
231  * @key: key to initialize
232  * @inum: host inode number
233  * @hash: extended attribute entry name hash
234  */
235 static inline void xent_key_init_hash(const struct ubifs_info *c,
236 				      union ubifs_key *key, ino_t inum,
237 				      uint32_t hash)
238 {
239 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
240 	key->u32[0] = inum;
241 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
242 }
243 
244 /**
245  * xent_key_init_flash - initialize on-flash extended attribute entry key.
246  * @c: UBIFS file-system description object
247  * @k: key to initialize
248  * @inum: host inode number
249  * @nm: extended attribute entry name and length
250  */
251 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
252 				       ino_t inum, const struct qstr *nm)
253 {
254 	union ubifs_key *key = k;
255 	uint32_t hash = c->key_hash(nm->name, nm->len);
256 
257 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
258 	key->j32[0] = cpu_to_le32(inum);
259 	key->j32[1] = cpu_to_le32(hash |
260 				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
261 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
262 }
263 
264 /**
265  * lowest_xent_key - get the lowest possible extended attribute entry key.
266  * @c: UBIFS file-system description object
267  * @key: where to store the lowest key
268  * @inum: host inode number
269  */
270 static inline void lowest_xent_key(const struct ubifs_info *c,
271 				   union ubifs_key *key, ino_t inum)
272 {
273 	key->u32[0] = inum;
274 	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
275 }
276 
277 /**
278  * data_key_init - initialize data key.
279  * @c: UBIFS file-system description object
280  * @key: key to initialize
281  * @inum: inode number
282  * @block: block number
283  */
284 static inline void data_key_init(const struct ubifs_info *c,
285 				 union ubifs_key *key, ino_t inum,
286 				 unsigned int block)
287 {
288 	ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
289 	key->u32[0] = inum;
290 	key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
291 }
292 
293 /**
294  * data_key_init_flash - initialize on-flash data key.
295  * @c: UBIFS file-system description object
296  * @k: key to initialize
297  * @inum: inode number
298  * @block: block number
299  */
300 static inline void data_key_init_flash(const struct ubifs_info *c, void *k,
301 				       ino_t inum, unsigned int block)
302 {
303 	union ubifs_key *key = k;
304 
305 	ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
306 	key->j32[0] = cpu_to_le32(inum);
307 	key->j32[1] = cpu_to_le32(block |
308 				  (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS));
309 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
310 }
311 
312 /**
313  * trun_key_init - initialize truncation node key.
314  * @c: UBIFS file-system description object
315  * @key: key to initialize
316  * @inum: inode number
317  *
318  * Note, UBIFS does not have truncation keys on the media and this function is
319  * only used for purposes of replay.
320  */
321 static inline void trun_key_init(const struct ubifs_info *c,
322 				 union ubifs_key *key, ino_t inum)
323 {
324 	key->u32[0] = inum;
325 	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
326 }
327 
328 /**
329  * key_type - get key type.
330  * @c: UBIFS file-system description object
331  * @key: key to get type of
332  */
333 static inline int key_type(const struct ubifs_info *c,
334 			   const union ubifs_key *key)
335 {
336 	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
337 }
338 
339 /**
340  * key_type_flash - get type of a on-flash formatted key.
341  * @c: UBIFS file-system description object
342  * @k: key to get type of
343  */
344 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
345 {
346 	const union ubifs_key *key = k;
347 
348 	return le32_to_cpu(key->u32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
349 }
350 
351 /**
352  * key_inum - fetch inode number from key.
353  * @c: UBIFS file-system description object
354  * @k: key to fetch inode number from
355  */
356 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
357 {
358 	const union ubifs_key *key = k;
359 
360 	return key->u32[0];
361 }
362 
363 /**
364  * key_inum_flash - fetch inode number from an on-flash formatted key.
365  * @c: UBIFS file-system description object
366  * @k: key to fetch inode number from
367  */
368 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
369 {
370 	const union ubifs_key *key = k;
371 
372 	return le32_to_cpu(key->j32[0]);
373 }
374 
375 /**
376  * key_hash - get directory entry hash.
377  * @c: UBIFS file-system description object
378  * @key: the key to get hash from
379  */
380 static inline int key_hash(const struct ubifs_info *c,
381 			   const union ubifs_key *key)
382 {
383 	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
384 }
385 
386 /**
387  * key_hash_flash - get directory entry hash from an on-flash formatted key.
388  * @c: UBIFS file-system description object
389  * @k: the key to get hash from
390  */
391 static inline int key_hash_flash(const struct ubifs_info *c, const void *k)
392 {
393 	const union ubifs_key *key = k;
394 
395 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
396 }
397 
398 /**
399  * key_block - get data block number.
400  * @c: UBIFS file-system description object
401  * @key: the key to get the block number from
402  */
403 static inline unsigned int key_block(const struct ubifs_info *c,
404 				     const union ubifs_key *key)
405 {
406 	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
407 }
408 
409 /**
410  * key_block_flash - get data block number from an on-flash formatted key.
411  * @c: UBIFS file-system description object
412  * @k: the key to get the block number from
413  */
414 static inline unsigned int key_block_flash(const struct ubifs_info *c,
415 					   const void *k)
416 {
417 	const union ubifs_key *key = k;
418 
419 	return le32_to_cpu(key->u32[1]) & UBIFS_S_KEY_BLOCK_MASK;
420 }
421 
422 /**
423  * key_read - transform a key to in-memory format.
424  * @c: UBIFS file-system description object
425  * @from: the key to transform
426  * @to: the key to store the result
427  */
428 static inline void key_read(const struct ubifs_info *c, const void *from,
429 			    union ubifs_key *to)
430 {
431 	const union ubifs_key *f = from;
432 
433 	to->u32[0] = le32_to_cpu(f->j32[0]);
434 	to->u32[1] = le32_to_cpu(f->j32[1]);
435 }
436 
437 /**
438  * key_write - transform a key from in-memory format.
439  * @c: UBIFS file-system description object
440  * @from: the key to transform
441  * @to: the key to store the result
442  */
443 static inline void key_write(const struct ubifs_info *c,
444 			     const union ubifs_key *from, void *to)
445 {
446 	union ubifs_key *t = to;
447 
448 	t->j32[0] = cpu_to_le32(from->u32[0]);
449 	t->j32[1] = cpu_to_le32(from->u32[1]);
450 	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
451 }
452 
453 /**
454  * key_write_idx - transform a key from in-memory format for the index.
455  * @c: UBIFS file-system description object
456  * @from: the key to transform
457  * @to: the key to store the result
458  */
459 static inline void key_write_idx(const struct ubifs_info *c,
460 				 const union ubifs_key *from, void *to)
461 {
462 	union ubifs_key *t = to;
463 
464 	t->j32[0] = cpu_to_le32(from->u32[0]);
465 	t->j32[1] = cpu_to_le32(from->u32[1]);
466 }
467 
468 /**
469  * key_copy - copy a key.
470  * @c: UBIFS file-system description object
471  * @from: the key to copy from
472  * @to: the key to copy to
473  */
474 static inline void key_copy(const struct ubifs_info *c,
475 			    const union ubifs_key *from, union ubifs_key *to)
476 {
477 	to->u64[0] = from->u64[0];
478 }
479 
480 /**
481  * keys_cmp - compare keys.
482  * @c: UBIFS file-system description object
483  * @key1: the first key to compare
484  * @key2: the second key to compare
485  *
486  * This function compares 2 keys and returns %-1 if @key1 is less than
487  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
488  */
489 static inline int keys_cmp(const struct ubifs_info *c,
490 			   const union ubifs_key *key1,
491 			   const union ubifs_key *key2)
492 {
493 	if (key1->u32[0] < key2->u32[0])
494 		return -1;
495 	if (key1->u32[0] > key2->u32[0])
496 		return 1;
497 	if (key1->u32[1] < key2->u32[1])
498 		return -1;
499 	if (key1->u32[1] > key2->u32[1])
500 		return 1;
501 
502 	return 0;
503 }
504 
505 /**
506  * keys_eq - determine if keys are equivalent.
507  * @c: UBIFS file-system description object
508  * @key1: the first key to compare
509  * @key2: the second key to compare
510  *
511  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
512  * %0 if not.
513  */
514 static inline int keys_eq(const struct ubifs_info *c,
515 			  const union ubifs_key *key1,
516 			  const union ubifs_key *key2)
517 {
518 	if (key1->u32[0] != key2->u32[0])
519 		return 0;
520 	if (key1->u32[1] != key2->u32[1])
521 		return 0;
522 	return 1;
523 }
524 
525 /**
526  * is_hash_key - is a key vulnerable to hash collisions.
527  * @c: UBIFS file-system description object
528  * @key: key
529  *
530  * This function returns %1 if @key is a hashed key or %0 otherwise.
531  */
532 static inline int is_hash_key(const struct ubifs_info *c,
533 			      const union ubifs_key *key)
534 {
535 	int type = key_type(c, key);
536 
537 	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
538 }
539 
540 /**
541  * key_max_inode_size - get maximum file size allowed by current key format.
542  * @c: UBIFS file-system description object
543  */
544 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
545 {
546 	switch (c->key_fmt) {
547 	case UBIFS_SIMPLE_KEY_FMT:
548 		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
549 	default:
550 		return 0;
551 	}
552 }
553 #endif /* !__UBIFS_KEY_H__ */
554