xref: /linux/fs/ubifs/key.h (revision 4b0aaacee51eb6592a03fdefd5ce97558518e291) 
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(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
165 	ubifs_assert(c, !nm->hash && !nm->minor_hash);
166 	key->u32[0] = inum;
167 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
168 }
169 
170 /**
171  * dent_key_init_hash - initialize directory entry key without re-calculating
172  *                      hash function.
173  * @c: UBIFS file-system description object
174  * @key: key to initialize
175  * @inum: parent inode number
176  * @hash: direntry name hash
177  */
178 static inline void dent_key_init_hash(const struct ubifs_info *c,
179 				      union ubifs_key *key, ino_t inum,
180 				      uint32_t hash)
181 {
182 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
183 	key->u32[0] = inum;
184 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
185 }
186 
187 /**
188  * dent_key_init_flash - initialize on-flash directory entry key.
189  * @c: UBIFS file-system description object
190  * @k: key to initialize
191  * @inum: parent inode number
192  * @nm: direntry name and length
193  */
194 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
195 				       ino_t inum,
196 				       const struct fscrypt_name *nm)
197 {
198 	union ubifs_key *key = k;
199 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
200 
201 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
202 	key->j32[0] = cpu_to_le32(inum);
203 	key->j32[1] = cpu_to_le32(hash |
204 				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
205 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
206 }
207 
208 /**
209  * lowest_dent_key - get the lowest possible directory entry key.
210  * @c: UBIFS file-system description object
211  * @key: where to store the lowest key
212  * @inum: parent inode number
213  */
214 static inline void lowest_dent_key(const struct ubifs_info *c,
215 				   union ubifs_key *key, ino_t inum)
216 {
217 	key->u32[0] = inum;
218 	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
219 }
220 
221 /**
222  * xent_key_init - initialize extended attribute entry key.
223  * @c: UBIFS file-system description object
224  * @key: key to initialize
225  * @inum: host inode number
226  * @nm: extended attribute entry name and length
227  */
228 static inline void xent_key_init(const struct ubifs_info *c,
229 				 union ubifs_key *key, ino_t inum,
230 				 const struct fscrypt_name *nm)
231 {
232 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
233 
234 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
235 	key->u32[0] = inum;
236 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
237 }
238 
239 /**
240  * xent_key_init_flash - initialize on-flash extended attribute entry key.
241  * @c: UBIFS file-system description object
242  * @k: key to initialize
243  * @inum: host inode number
244  * @nm: extended attribute entry name and length
245  */
246 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
247 				       ino_t inum, const struct fscrypt_name *nm)
248 {
249 	union ubifs_key *key = k;
250 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
251 
252 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
253 	key->j32[0] = cpu_to_le32(inum);
254 	key->j32[1] = cpu_to_le32(hash |
255 				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
256 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
257 }
258 
259 /**
260  * lowest_xent_key - get the lowest possible extended attribute entry key.
261  * @c: UBIFS file-system description object
262  * @key: where to store the lowest key
263  * @inum: host inode number
264  */
265 static inline void lowest_xent_key(const struct ubifs_info *c,
266 				   union ubifs_key *key, ino_t inum)
267 {
268 	key->u32[0] = inum;
269 	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
270 }
271 
272 /**
273  * data_key_init - initialize data key.
274  * @c: UBIFS file-system description object
275  * @key: key to initialize
276  * @inum: inode number
277  * @block: block number
278  */
279 static inline void data_key_init(const struct ubifs_info *c,
280 				 union ubifs_key *key, ino_t inum,
281 				 unsigned int block)
282 {
283 	ubifs_assert(c, !(block & ~UBIFS_S_KEY_BLOCK_MASK));
284 	key->u32[0] = inum;
285 	key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
286 }
287 
288 /**
289  * highest_data_key - get the highest possible data key for an inode.
290  * @c: UBIFS file-system description object
291  * @key: key to initialize
292  * @inum: inode number
293  */
294 static inline void highest_data_key(const struct ubifs_info *c,
295 				   union ubifs_key *key, ino_t inum)
296 {
297 	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
298 }
299 
300 /**
301  * trun_key_init - initialize truncation node key.
302  * @c: UBIFS file-system description object
303  * @key: key to initialize
304  * @inum: inode number
305  *
306  * Note, UBIFS does not have truncation keys on the media and this function is
307  * only used for purposes of replay.
308  */
309 static inline void trun_key_init(const struct ubifs_info *c,
310 				 union ubifs_key *key, ino_t inum)
311 {
312 	key->u32[0] = inum;
313 	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
314 }
315 
316 /**
317  * invalid_key_init - initialize invalid node key.
318  * @c: UBIFS file-system description object
319  * @key: key to initialize
320  *
321  * This is a helper function which marks a @key object as invalid.
322  */
323 static inline void invalid_key_init(const struct ubifs_info *c,
324 				    union ubifs_key *key)
325 {
326 	key->u32[0] = 0xDEADBEAF;
327 	key->u32[1] = UBIFS_INVALID_KEY;
328 }
329 
330 /**
331  * key_type - get key type.
332  * @c: UBIFS file-system description object
333  * @key: key to get type of
334  */
335 static inline int key_type(const struct ubifs_info *c,
336 			   const union ubifs_key *key)
337 {
338 	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
339 }
340 
341 /**
342  * key_type_flash - get type of a on-flash formatted key.
343  * @c: UBIFS file-system description object
344  * @k: key to get type of
345  */
346 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
347 {
348 	const union ubifs_key *key = k;
349 
350 	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
351 }
352 
353 /**
354  * key_inum - fetch inode number from key.
355  * @c: UBIFS file-system description object
356  * @k: key to fetch inode number from
357  */
358 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
359 {
360 	const union ubifs_key *key = k;
361 
362 	return key->u32[0];
363 }
364 
365 /**
366  * key_inum_flash - fetch inode number from an on-flash formatted key.
367  * @c: UBIFS file-system description object
368  * @k: key to fetch inode number from
369  */
370 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
371 {
372 	const union ubifs_key *key = k;
373 
374 	return le32_to_cpu(key->j32[0]);
375 }
376 
377 /**
378  * key_hash - get directory entry hash.
379  * @c: UBIFS file-system description object
380  * @key: the key to get hash from
381  */
382 static inline uint32_t key_hash(const struct ubifs_info *c,
383 				const union ubifs_key *key)
384 {
385 	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
386 }
387 
388 /**
389  * key_hash_flash - get directory entry hash from an on-flash formatted key.
390  * @c: UBIFS file-system description object
391  * @k: the key to get hash from
392  */
393 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
394 {
395 	const union ubifs_key *key = k;
396 
397 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
398 }
399 
400 /**
401  * key_block - get data block number.
402  * @c: UBIFS file-system description object
403  * @key: the key to get the block number from
404  */
405 static inline unsigned int key_block(const struct ubifs_info *c,
406 				     const union ubifs_key *key)
407 {
408 	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
409 }
410 
411 /**
412  * key_block_flash - get data block number from an on-flash formatted key.
413  * @c: UBIFS file-system description object
414  * @k: the key to get the block number from
415  */
416 static inline unsigned int key_block_flash(const struct ubifs_info *c,
417 					   const void *k)
418 {
419 	const union ubifs_key *key = k;
420 
421 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
422 }
423 
424 /**
425  * key_read - transform a key to in-memory format.
426  * @c: UBIFS file-system description object
427  * @from: the key to transform
428  * @to: the key to store the result
429  */
430 static inline void key_read(const struct ubifs_info *c, const void *from,
431 			    union ubifs_key *to)
432 {
433 	const union ubifs_key *f = from;
434 
435 	to->u32[0] = le32_to_cpu(f->j32[0]);
436 	to->u32[1] = le32_to_cpu(f->j32[1]);
437 }
438 
439 /**
440  * key_write - transform a key from in-memory format.
441  * @c: UBIFS file-system description object
442  * @from: the key to transform
443  * @to: the key to store the result
444  */
445 static inline void key_write(const struct ubifs_info *c,
446 			     const union ubifs_key *from, void *to)
447 {
448 	union ubifs_key *t = to;
449 
450 	t->j32[0] = cpu_to_le32(from->u32[0]);
451 	t->j32[1] = cpu_to_le32(from->u32[1]);
452 	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
453 }
454 
455 /**
456  * key_write_idx - transform a key from in-memory format for the index.
457  * @c: UBIFS file-system description object
458  * @from: the key to transform
459  * @to: the key to store the result
460  */
461 static inline void key_write_idx(const struct ubifs_info *c,
462 				 const union ubifs_key *from, void *to)
463 {
464 	union ubifs_key *t = to;
465 
466 	t->j32[0] = cpu_to_le32(from->u32[0]);
467 	t->j32[1] = cpu_to_le32(from->u32[1]);
468 }
469 
470 /**
471  * key_copy - copy a key.
472  * @c: UBIFS file-system description object
473  * @from: the key to copy from
474  * @to: the key to copy to
475  */
476 static inline void key_copy(const struct ubifs_info *c,
477 			    const union ubifs_key *from, union ubifs_key *to)
478 {
479 	to->u64[0] = from->u64[0];
480 }
481 
482 /**
483  * keys_cmp - compare keys.
484  * @c: UBIFS file-system description object
485  * @key1: the first key to compare
486  * @key2: the second key to compare
487  *
488  * This function compares 2 keys and returns %-1 if @key1 is less than
489  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
490  */
491 static inline int keys_cmp(const struct ubifs_info *c,
492 			   const union ubifs_key *key1,
493 			   const union ubifs_key *key2)
494 {
495 	if (key1->u32[0] < key2->u32[0])
496 		return -1;
497 	if (key1->u32[0] > key2->u32[0])
498 		return 1;
499 	if (key1->u32[1] < key2->u32[1])
500 		return -1;
501 	if (key1->u32[1] > key2->u32[1])
502 		return 1;
503 
504 	return 0;
505 }
506 
507 /**
508  * keys_eq - determine if keys are equivalent.
509  * @c: UBIFS file-system description object
510  * @key1: the first key to compare
511  * @key2: the second key to compare
512  *
513  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
514  * %0 if not.
515  */
516 static inline int keys_eq(const struct ubifs_info *c,
517 			  const union ubifs_key *key1,
518 			  const union ubifs_key *key2)
519 {
520 	if (key1->u32[0] != key2->u32[0])
521 		return 0;
522 	if (key1->u32[1] != key2->u32[1])
523 		return 0;
524 	return 1;
525 }
526 
527 /**
528  * is_hash_key - is a key vulnerable to hash collisions.
529  * @c: UBIFS file-system description object
530  * @key: key
531  *
532  * This function returns %1 if @key is a hashed key or %0 otherwise.
533  */
534 static inline int is_hash_key(const struct ubifs_info *c,
535 			      const union ubifs_key *key)
536 {
537 	int type = key_type(c, key);
538 
539 	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
540 }
541 
542 /**
543  * key_max_inode_size - get maximum file size allowed by current key format.
544  * @c: UBIFS file-system description object
545  */
546 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
547 {
548 	switch (c->key_fmt) {
549 	case UBIFS_SIMPLE_KEY_FMT:
550 		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
551 	default:
552 		return 0;
553 	}
554 }
555 
556 #endif /* !__UBIFS_KEY_H__ */
557