xref: /openbmc/linux/fs/ubifs/key.h (revision b6dcefde) 
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  * key_type - get key type.
310  * @c: UBIFS file-system description object
311  * @key: key to get type of
312  */
313 static inline int key_type(const struct ubifs_info *c,
314 			   const union ubifs_key *key)
315 {
316 	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
317 }
318 
319 /**
320  * key_type_flash - get type of a on-flash formatted key.
321  * @c: UBIFS file-system description object
322  * @k: key to get type of
323  */
324 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
325 {
326 	const union ubifs_key *key = k;
327 
328 	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
329 }
330 
331 /**
332  * key_inum - fetch inode number from key.
333  * @c: UBIFS file-system description object
334  * @k: key to fetch inode number from
335  */
336 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
337 {
338 	const union ubifs_key *key = k;
339 
340 	return key->u32[0];
341 }
342 
343 /**
344  * key_inum_flash - fetch inode number from an on-flash formatted key.
345  * @c: UBIFS file-system description object
346  * @k: key to fetch inode number from
347  */
348 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
349 {
350 	const union ubifs_key *key = k;
351 
352 	return le32_to_cpu(key->j32[0]);
353 }
354 
355 /**
356  * key_hash - get directory entry hash.
357  * @c: UBIFS file-system description object
358  * @key: the key to get hash from
359  */
360 static inline uint32_t key_hash(const struct ubifs_info *c,
361 				const union ubifs_key *key)
362 {
363 	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
364 }
365 
366 /**
367  * key_hash_flash - get directory entry hash from an on-flash formatted key.
368  * @c: UBIFS file-system description object
369  * @k: the key to get hash from
370  */
371 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
372 {
373 	const union ubifs_key *key = k;
374 
375 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
376 }
377 
378 /**
379  * key_block - get data block number.
380  * @c: UBIFS file-system description object
381  * @key: the key to get the block number from
382  */
383 static inline unsigned int key_block(const struct ubifs_info *c,
384 				     const union ubifs_key *key)
385 {
386 	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
387 }
388 
389 /**
390  * key_block_flash - get data block number from an on-flash formatted key.
391  * @c: UBIFS file-system description object
392  * @k: the key to get the block number from
393  */
394 static inline unsigned int key_block_flash(const struct ubifs_info *c,
395 					   const void *k)
396 {
397 	const union ubifs_key *key = k;
398 
399 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
400 }
401 
402 /**
403  * key_read - transform a key to in-memory format.
404  * @c: UBIFS file-system description object
405  * @from: the key to transform
406  * @to: the key to store the result
407  */
408 static inline void key_read(const struct ubifs_info *c, const void *from,
409 			    union ubifs_key *to)
410 {
411 	const union ubifs_key *f = from;
412 
413 	to->u32[0] = le32_to_cpu(f->j32[0]);
414 	to->u32[1] = le32_to_cpu(f->j32[1]);
415 }
416 
417 /**
418  * key_write - transform a key from in-memory format.
419  * @c: UBIFS file-system description object
420  * @from: the key to transform
421  * @to: the key to store the result
422  */
423 static inline void key_write(const struct ubifs_info *c,
424 			     const union ubifs_key *from, void *to)
425 {
426 	union ubifs_key *t = to;
427 
428 	t->j32[0] = cpu_to_le32(from->u32[0]);
429 	t->j32[1] = cpu_to_le32(from->u32[1]);
430 	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
431 }
432 
433 /**
434  * key_write_idx - transform a key from in-memory format for the index.
435  * @c: UBIFS file-system description object
436  * @from: the key to transform
437  * @to: the key to store the result
438  */
439 static inline void key_write_idx(const struct ubifs_info *c,
440 				 const union ubifs_key *from, void *to)
441 {
442 	union ubifs_key *t = to;
443 
444 	t->j32[0] = cpu_to_le32(from->u32[0]);
445 	t->j32[1] = cpu_to_le32(from->u32[1]);
446 }
447 
448 /**
449  * key_copy - copy a key.
450  * @c: UBIFS file-system description object
451  * @from: the key to copy from
452  * @to: the key to copy to
453  */
454 static inline void key_copy(const struct ubifs_info *c,
455 			    const union ubifs_key *from, union ubifs_key *to)
456 {
457 	to->u64[0] = from->u64[0];
458 }
459 
460 /**
461  * keys_cmp - compare keys.
462  * @c: UBIFS file-system description object
463  * @key1: the first key to compare
464  * @key2: the second key to compare
465  *
466  * This function compares 2 keys and returns %-1 if @key1 is less than
467  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
468  */
469 static inline int keys_cmp(const struct ubifs_info *c,
470 			   const union ubifs_key *key1,
471 			   const union ubifs_key *key2)
472 {
473 	if (key1->u32[0] < key2->u32[0])
474 		return -1;
475 	if (key1->u32[0] > key2->u32[0])
476 		return 1;
477 	if (key1->u32[1] < key2->u32[1])
478 		return -1;
479 	if (key1->u32[1] > key2->u32[1])
480 		return 1;
481 
482 	return 0;
483 }
484 
485 /**
486  * keys_eq - determine if keys are equivalent.
487  * @c: UBIFS file-system description object
488  * @key1: the first key to compare
489  * @key2: the second key to compare
490  *
491  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
492  * %0 if not.
493  */
494 static inline int keys_eq(const struct ubifs_info *c,
495 			  const union ubifs_key *key1,
496 			  const union ubifs_key *key2)
497 {
498 	if (key1->u32[0] != key2->u32[0])
499 		return 0;
500 	if (key1->u32[1] != key2->u32[1])
501 		return 0;
502 	return 1;
503 }
504 
505 /**
506  * is_hash_key - is a key vulnerable to hash collisions.
507  * @c: UBIFS file-system description object
508  * @key: key
509  *
510  * This function returns %1 if @key is a hashed key or %0 otherwise.
511  */
512 static inline int is_hash_key(const struct ubifs_info *c,
513 			      const union ubifs_key *key)
514 {
515 	int type = key_type(c, key);
516 
517 	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
518 }
519 
520 /**
521  * key_max_inode_size - get maximum file size allowed by current key format.
522  * @c: UBIFS file-system description object
523  */
524 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
525 {
526 	switch (c->key_fmt) {
527 	case UBIFS_SIMPLE_KEY_FMT:
528 		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
529 	default:
530 		return 0;
531 	}
532 }
533 
534 #endif /* !__UBIFS_KEY_H__ */
535