xref: /openbmc/linux/fs/ubifs/key.h (revision 4f205687) 
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 (*str) {
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
157  */
158 static inline void dent_key_init(const struct ubifs_info *c,
159 				 union ubifs_key *key, ino_t inum,
160 				 const struct qstr *nm)
161 {
162 	uint32_t hash = c->key_hash(nm->name, nm->len);
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, const struct qstr *nm)
195 {
196 	union ubifs_key *key = k;
197 	uint32_t hash = c->key_hash(nm->name, nm->len);
198 
199 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
200 	key->j32[0] = cpu_to_le32(inum);
201 	key->j32[1] = cpu_to_le32(hash |
202 				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
203 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
204 }
205 
206 /**
207  * lowest_dent_key - get the lowest possible directory entry key.
208  * @c: UBIFS file-system description object
209  * @key: where to store the lowest key
210  * @inum: parent inode number
211  */
212 static inline void lowest_dent_key(const struct ubifs_info *c,
213 				   union ubifs_key *key, ino_t inum)
214 {
215 	key->u32[0] = inum;
216 	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
217 }
218 
219 /**
220  * xent_key_init - initialize extended attribute entry key.
221  * @c: UBIFS file-system description object
222  * @key: key to initialize
223  * @inum: host inode number
224  * @nm: extended attribute entry name and length
225  */
226 static inline void xent_key_init(const struct ubifs_info *c,
227 				 union ubifs_key *key, ino_t inum,
228 				 const struct qstr *nm)
229 {
230 	uint32_t hash = c->key_hash(nm->name, nm->len);
231 
232 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
233 	key->u32[0] = inum;
234 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
235 }
236 
237 /**
238  * xent_key_init_flash - initialize on-flash extended attribute entry key.
239  * @c: UBIFS file-system description object
240  * @k: key to initialize
241  * @inum: host inode number
242  * @nm: extended attribute entry name and length
243  */
244 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
245 				       ino_t inum, const struct qstr *nm)
246 {
247 	union ubifs_key *key = k;
248 	uint32_t hash = c->key_hash(nm->name, nm->len);
249 
250 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
251 	key->j32[0] = cpu_to_le32(inum);
252 	key->j32[1] = cpu_to_le32(hash |
253 				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
254 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
255 }
256 
257 /**
258  * lowest_xent_key - get the lowest possible extended attribute entry key.
259  * @c: UBIFS file-system description object
260  * @key: where to store the lowest key
261  * @inum: host inode number
262  */
263 static inline void lowest_xent_key(const struct ubifs_info *c,
264 				   union ubifs_key *key, ino_t inum)
265 {
266 	key->u32[0] = inum;
267 	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
268 }
269 
270 /**
271  * data_key_init - initialize data key.
272  * @c: UBIFS file-system description object
273  * @key: key to initialize
274  * @inum: inode number
275  * @block: block number
276  */
277 static inline void data_key_init(const struct ubifs_info *c,
278 				 union ubifs_key *key, ino_t inum,
279 				 unsigned int block)
280 {
281 	ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
282 	key->u32[0] = inum;
283 	key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
284 }
285 
286 /**
287  * highest_data_key - get the highest possible data key for an inode.
288  * @c: UBIFS file-system description object
289  * @key: key to initialize
290  * @inum: inode number
291  */
292 static inline void highest_data_key(const struct ubifs_info *c,
293 				   union ubifs_key *key, ino_t inum)
294 {
295 	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
296 }
297 
298 /**
299  * trun_key_init - initialize truncation node key.
300  * @c: UBIFS file-system description object
301  * @key: key to initialize
302  * @inum: inode number
303  *
304  * Note, UBIFS does not have truncation keys on the media and this function is
305  * only used for purposes of replay.
306  */
307 static inline void trun_key_init(const struct ubifs_info *c,
308 				 union ubifs_key *key, ino_t inum)
309 {
310 	key->u32[0] = inum;
311 	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
312 }
313 
314 /**
315  * invalid_key_init - initialize invalid node key.
316  * @c: UBIFS file-system description object
317  * @key: key to initialize
318  *
319  * This is a helper function which marks a @key object as invalid.
320  */
321 static inline void invalid_key_init(const struct ubifs_info *c,
322 				    union ubifs_key *key)
323 {
324 	key->u32[0] = 0xDEADBEAF;
325 	key->u32[1] = UBIFS_INVALID_KEY;
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->j32[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 uint32_t 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 uint32_t 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->j32[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 
554 #endif /* !__UBIFS_KEY_H__ */
555