xref: /linux/fs/ubifs/key.h (revision ca55b2fef3a9373fcfc30f82fd26bc7fccbda732) 
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_mask_hash - mask a valid hash value.
42  * @val: value to be masked
43  *
44  * We use hash values as offset in directories, so values %0 and %1 are
45  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
46  * function makes sure the reserved values are not used.
47  */
48 static inline uint32_t key_mask_hash(uint32_t hash)
49 {
50 	hash &= UBIFS_S_KEY_HASH_MASK;
51 	if (unlikely(hash <= 2))
52 		hash += 3;
53 	return hash;
54 }
55 
56 /**
57  * key_r5_hash - R5 hash function (borrowed from reiserfs).
58  * @s: direntry name
59  * @len: name length
60  */
61 static inline uint32_t key_r5_hash(const char *s, int len)
62 {
63 	uint32_t a = 0;
64 	const signed char *str = (const signed char *)s;
65 
66 	while (*str) {
67 		a += *str << 4;
68 		a += *str >> 4;
69 		a *= 11;
70 		str++;
71 	}
72 
73 	return key_mask_hash(a);
74 }
75 
76 /**
77  * key_test_hash - testing hash function.
78  * @str: direntry name
79  * @len: name length
80  */
81 static inline uint32_t key_test_hash(const char *str, int len)
82 {
83 	uint32_t a = 0;
84 
85 	len = min_t(uint32_t, len, 4);
86 	memcpy(&a, str, len);
87 	return key_mask_hash(a);
88 }
89 
90 /**
91  * ino_key_init - initialize inode key.
92  * @c: UBIFS file-system description object
93  * @key: key to initialize
94  * @inum: inode number
95  */
96 static inline void ino_key_init(const struct ubifs_info *c,
97 				union ubifs_key *key, ino_t inum)
98 {
99 	key->u32[0] = inum;
100 	key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
101 }
102 
103 /**
104  * ino_key_init_flash - initialize on-flash inode key.
105  * @c: UBIFS file-system description object
106  * @k: key to initialize
107  * @inum: inode number
108  */
109 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
110 				      ino_t inum)
111 {
112 	union ubifs_key *key = k;
113 
114 	key->j32[0] = cpu_to_le32(inum);
115 	key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
116 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
117 }
118 
119 /**
120  * lowest_ino_key - get the lowest possible inode key.
121  * @c: UBIFS file-system description object
122  * @key: key to initialize
123  * @inum: inode number
124  */
125 static inline void lowest_ino_key(const struct ubifs_info *c,
126 				union ubifs_key *key, ino_t inum)
127 {
128 	key->u32[0] = inum;
129 	key->u32[1] = 0;
130 }
131 
132 /**
133  * highest_ino_key - get the highest possible inode key.
134  * @c: UBIFS file-system description object
135  * @key: key to initialize
136  * @inum: inode number
137  */
138 static inline void highest_ino_key(const struct ubifs_info *c,
139 				union ubifs_key *key, ino_t inum)
140 {
141 	key->u32[0] = inum;
142 	key->u32[1] = 0xffffffff;
143 }
144 
145 /**
146  * dent_key_init - initialize directory entry key.
147  * @c: UBIFS file-system description object
148  * @key: key to initialize
149  * @inum: parent inode number
150  * @nm: direntry name and length
151  */
152 static inline void dent_key_init(const struct ubifs_info *c,
153 				 union ubifs_key *key, ino_t inum,
154 				 const struct qstr *nm)
155 {
156 	uint32_t hash = c->key_hash(nm->name, nm->len);
157 
158 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
159 	key->u32[0] = inum;
160 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
161 }
162 
163 /**
164  * dent_key_init_hash - initialize directory entry key without re-calculating
165  *                      hash function.
166  * @c: UBIFS file-system description object
167  * @key: key to initialize
168  * @inum: parent inode number
169  * @hash: direntry name hash
170  */
171 static inline void dent_key_init_hash(const struct ubifs_info *c,
172 				      union ubifs_key *key, ino_t inum,
173 				      uint32_t hash)
174 {
175 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
176 	key->u32[0] = inum;
177 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
178 }
179 
180 /**
181  * dent_key_init_flash - initialize on-flash directory entry key.
182  * @c: UBIFS file-system description object
183  * @k: key to initialize
184  * @inum: parent inode number
185  * @nm: direntry name and length
186  */
187 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
188 				       ino_t inum, const struct qstr *nm)
189 {
190 	union ubifs_key *key = k;
191 	uint32_t hash = c->key_hash(nm->name, nm->len);
192 
193 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
194 	key->j32[0] = cpu_to_le32(inum);
195 	key->j32[1] = cpu_to_le32(hash |
196 				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
197 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
198 }
199 
200 /**
201  * lowest_dent_key - get the lowest possible directory entry key.
202  * @c: UBIFS file-system description object
203  * @key: where to store the lowest key
204  * @inum: parent inode number
205  */
206 static inline void lowest_dent_key(const struct ubifs_info *c,
207 				   union ubifs_key *key, ino_t inum)
208 {
209 	key->u32[0] = inum;
210 	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
211 }
212 
213 /**
214  * xent_key_init - initialize extended attribute entry key.
215  * @c: UBIFS file-system description object
216  * @key: key to initialize
217  * @inum: host inode number
218  * @nm: extended attribute entry name and length
219  */
220 static inline void xent_key_init(const struct ubifs_info *c,
221 				 union ubifs_key *key, ino_t inum,
222 				 const struct qstr *nm)
223 {
224 	uint32_t hash = c->key_hash(nm->name, nm->len);
225 
226 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
227 	key->u32[0] = inum;
228 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
229 }
230 
231 /**
232  * xent_key_init_flash - initialize on-flash extended attribute entry key.
233  * @c: UBIFS file-system description object
234  * @k: key to initialize
235  * @inum: host inode number
236  * @nm: extended attribute entry name and length
237  */
238 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
239 				       ino_t inum, const struct qstr *nm)
240 {
241 	union ubifs_key *key = k;
242 	uint32_t hash = c->key_hash(nm->name, nm->len);
243 
244 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
245 	key->j32[0] = cpu_to_le32(inum);
246 	key->j32[1] = cpu_to_le32(hash |
247 				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
248 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
249 }
250 
251 /**
252  * lowest_xent_key - get the lowest possible extended attribute entry key.
253  * @c: UBIFS file-system description object
254  * @key: where to store the lowest key
255  * @inum: host inode number
256  */
257 static inline void lowest_xent_key(const struct ubifs_info *c,
258 				   union ubifs_key *key, ino_t inum)
259 {
260 	key->u32[0] = inum;
261 	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
262 }
263 
264 /**
265  * data_key_init - initialize data key.
266  * @c: UBIFS file-system description object
267  * @key: key to initialize
268  * @inum: inode number
269  * @block: block number
270  */
271 static inline void data_key_init(const struct ubifs_info *c,
272 				 union ubifs_key *key, ino_t inum,
273 				 unsigned int block)
274 {
275 	ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
276 	key->u32[0] = inum;
277 	key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
278 }
279 
280 /**
281  * highest_data_key - get the highest possible data key for an inode.
282  * @c: UBIFS file-system description object
283  * @key: key to initialize
284  * @inum: inode number
285  */
286 static inline void highest_data_key(const struct ubifs_info *c,
287 				   union ubifs_key *key, ino_t inum)
288 {
289 	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
290 }
291 
292 /**
293  * trun_key_init - initialize truncation node key.
294  * @c: UBIFS file-system description object
295  * @key: key to initialize
296  * @inum: inode number
297  *
298  * Note, UBIFS does not have truncation keys on the media and this function is
299  * only used for purposes of replay.
300  */
301 static inline void trun_key_init(const struct ubifs_info *c,
302 				 union ubifs_key *key, ino_t inum)
303 {
304 	key->u32[0] = inum;
305 	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
306 }
307 
308 /**
309  * invalid_key_init - initialize invalid node key.
310  * @c: UBIFS file-system description object
311  * @key: key to initialize
312  *
313  * This is a helper function which marks a @key object as invalid.
314  */
315 static inline void invalid_key_init(const struct ubifs_info *c,
316 				    union ubifs_key *key)
317 {
318 	key->u32[0] = 0xDEADBEAF;
319 	key->u32[1] = UBIFS_INVALID_KEY;
320 }
321 
322 /**
323  * key_type - get key type.
324  * @c: UBIFS file-system description object
325  * @key: key to get type of
326  */
327 static inline int key_type(const struct ubifs_info *c,
328 			   const union ubifs_key *key)
329 {
330 	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
331 }
332 
333 /**
334  * key_type_flash - get type of a on-flash formatted key.
335  * @c: UBIFS file-system description object
336  * @k: key to get type of
337  */
338 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
339 {
340 	const union ubifs_key *key = k;
341 
342 	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
343 }
344 
345 /**
346  * key_inum - fetch inode number from key.
347  * @c: UBIFS file-system description object
348  * @k: key to fetch inode number from
349  */
350 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
351 {
352 	const union ubifs_key *key = k;
353 
354 	return key->u32[0];
355 }
356 
357 /**
358  * key_inum_flash - fetch inode number from an on-flash formatted key.
359  * @c: UBIFS file-system description object
360  * @k: key to fetch inode number from
361  */
362 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
363 {
364 	const union ubifs_key *key = k;
365 
366 	return le32_to_cpu(key->j32[0]);
367 }
368 
369 /**
370  * key_hash - get directory entry hash.
371  * @c: UBIFS file-system description object
372  * @key: the key to get hash from
373  */
374 static inline uint32_t key_hash(const struct ubifs_info *c,
375 				const union ubifs_key *key)
376 {
377 	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
378 }
379 
380 /**
381  * key_hash_flash - get directory entry hash from an on-flash formatted key.
382  * @c: UBIFS file-system description object
383  * @k: the key to get hash from
384  */
385 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
386 {
387 	const union ubifs_key *key = k;
388 
389 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
390 }
391 
392 /**
393  * key_block - get data block number.
394  * @c: UBIFS file-system description object
395  * @key: the key to get the block number from
396  */
397 static inline unsigned int key_block(const struct ubifs_info *c,
398 				     const union ubifs_key *key)
399 {
400 	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
401 }
402 
403 /**
404  * key_block_flash - get data block number from an on-flash formatted key.
405  * @c: UBIFS file-system description object
406  * @k: the key to get the block number from
407  */
408 static inline unsigned int key_block_flash(const struct ubifs_info *c,
409 					   const void *k)
410 {
411 	const union ubifs_key *key = k;
412 
413 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
414 }
415 
416 /**
417  * key_read - transform a key to in-memory format.
418  * @c: UBIFS file-system description object
419  * @from: the key to transform
420  * @to: the key to store the result
421  */
422 static inline void key_read(const struct ubifs_info *c, const void *from,
423 			    union ubifs_key *to)
424 {
425 	const union ubifs_key *f = from;
426 
427 	to->u32[0] = le32_to_cpu(f->j32[0]);
428 	to->u32[1] = le32_to_cpu(f->j32[1]);
429 }
430 
431 /**
432  * key_write - transform a key from in-memory format.
433  * @c: UBIFS file-system description object
434  * @from: the key to transform
435  * @to: the key to store the result
436  */
437 static inline void key_write(const struct ubifs_info *c,
438 			     const union ubifs_key *from, void *to)
439 {
440 	union ubifs_key *t = to;
441 
442 	t->j32[0] = cpu_to_le32(from->u32[0]);
443 	t->j32[1] = cpu_to_le32(from->u32[1]);
444 	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
445 }
446 
447 /**
448  * key_write_idx - transform a key from in-memory format for the index.
449  * @c: UBIFS file-system description object
450  * @from: the key to transform
451  * @to: the key to store the result
452  */
453 static inline void key_write_idx(const struct ubifs_info *c,
454 				 const union ubifs_key *from, void *to)
455 {
456 	union ubifs_key *t = to;
457 
458 	t->j32[0] = cpu_to_le32(from->u32[0]);
459 	t->j32[1] = cpu_to_le32(from->u32[1]);
460 }
461 
462 /**
463  * key_copy - copy a key.
464  * @c: UBIFS file-system description object
465  * @from: the key to copy from
466  * @to: the key to copy to
467  */
468 static inline void key_copy(const struct ubifs_info *c,
469 			    const union ubifs_key *from, union ubifs_key *to)
470 {
471 	to->u64[0] = from->u64[0];
472 }
473 
474 /**
475  * keys_cmp - compare keys.
476  * @c: UBIFS file-system description object
477  * @key1: the first key to compare
478  * @key2: the second key to compare
479  *
480  * This function compares 2 keys and returns %-1 if @key1 is less than
481  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
482  */
483 static inline int keys_cmp(const struct ubifs_info *c,
484 			   const union ubifs_key *key1,
485 			   const union ubifs_key *key2)
486 {
487 	if (key1->u32[0] < key2->u32[0])
488 		return -1;
489 	if (key1->u32[0] > key2->u32[0])
490 		return 1;
491 	if (key1->u32[1] < key2->u32[1])
492 		return -1;
493 	if (key1->u32[1] > key2->u32[1])
494 		return 1;
495 
496 	return 0;
497 }
498 
499 /**
500  * keys_eq - determine if keys are equivalent.
501  * @c: UBIFS file-system description object
502  * @key1: the first key to compare
503  * @key2: the second key to compare
504  *
505  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
506  * %0 if not.
507  */
508 static inline int keys_eq(const struct ubifs_info *c,
509 			  const union ubifs_key *key1,
510 			  const union ubifs_key *key2)
511 {
512 	if (key1->u32[0] != key2->u32[0])
513 		return 0;
514 	if (key1->u32[1] != key2->u32[1])
515 		return 0;
516 	return 1;
517 }
518 
519 /**
520  * is_hash_key - is a key vulnerable to hash collisions.
521  * @c: UBIFS file-system description object
522  * @key: key
523  *
524  * This function returns %1 if @key is a hashed key or %0 otherwise.
525  */
526 static inline int is_hash_key(const struct ubifs_info *c,
527 			      const union ubifs_key *key)
528 {
529 	int type = key_type(c, key);
530 
531 	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
532 }
533 
534 /**
535  * key_max_inode_size - get maximum file size allowed by current key format.
536  * @c: UBIFS file-system description object
537  */
538 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
539 {
540 	switch (c->key_fmt) {
541 	case UBIFS_SIMPLE_KEY_FMT:
542 		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
543 	default:
544 		return 0;
545 	}
546 }
547 
548 #endif /* !__UBIFS_KEY_H__ */
549