xref: /openbmc/linux/fs/ubifs/key.h (revision 9dbbc3b9) 
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * This file is part of UBIFS.
4  *
5  * Copyright (C) 2006-2008 Nokia Corporation.
6  *
7  * Authors: Artem Bityutskiy (Битюцкий Артём)
8  *          Adrian Hunter
9  */
10 
11 /*
12  * This header contains various key-related definitions and helper function.
13  * UBIFS allows several key schemes, so we access key fields only via these
14  * helpers. At the moment only one key scheme is supported.
15  *
16  * Simple key scheme
17  * ~~~~~~~~~~~~~~~~~
18  *
19  * Keys are 64-bits long. First 32-bits are inode number (parent inode number
20  * in case of direntry key). Next 3 bits are node type. The last 29 bits are
21  * 4KiB offset in case of inode node, and direntry hash in case of a direntry
22  * node. We use "r5" hash borrowed from reiserfs.
23  */
24 
25 /*
26  * Lot's of the key helpers require a struct ubifs_info *c as the first parameter.
27  * But we are not using it at all currently. That's designed for future extensions of
28  * different c->key_format. But right now, there is only one key type, UBIFS_SIMPLE_KEY_FMT.
29  */
30 
31 #ifndef __UBIFS_KEY_H__
32 #define __UBIFS_KEY_H__
33 
34 /**
35  * key_mask_hash - mask a valid hash value.
36  * @val: value to be masked
37  *
38  * We use hash values as offset in directories, so values %0 and %1 are
39  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
40  * function makes sure the reserved values are not used.
41  */
42 static inline uint32_t key_mask_hash(uint32_t hash)
43 {
44 	hash &= UBIFS_S_KEY_HASH_MASK;
45 	if (unlikely(hash <= 2))
46 		hash += 3;
47 	return hash;
48 }
49 
50 /**
51  * key_r5_hash - R5 hash function (borrowed from reiserfs).
52  * @s: direntry name
53  * @len: name length
54  */
55 static inline uint32_t key_r5_hash(const char *s, int len)
56 {
57 	uint32_t a = 0;
58 	const signed char *str = (const signed char *)s;
59 
60 	while (len--) {
61 		a += *str << 4;
62 		a += *str >> 4;
63 		a *= 11;
64 		str++;
65 	}
66 
67 	return key_mask_hash(a);
68 }
69 
70 /**
71  * key_test_hash - testing hash function.
72  * @str: direntry name
73  * @len: name length
74  */
75 static inline uint32_t key_test_hash(const char *str, int len)
76 {
77 	uint32_t a = 0;
78 
79 	len = min_t(uint32_t, len, 4);
80 	memcpy(&a, str, len);
81 	return key_mask_hash(a);
82 }
83 
84 /**
85  * ino_key_init - initialize inode key.
86  * @c: UBIFS file-system description object
87  * @key: key to initialize
88  * @inum: inode number
89  */
90 static inline void ino_key_init(const struct ubifs_info *c,
91 				union ubifs_key *key, ino_t inum)
92 {
93 	key->u32[0] = inum;
94 	key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
95 }
96 
97 /**
98  * ino_key_init_flash - initialize on-flash inode key.
99  * @c: UBIFS file-system description object
100  * @k: key to initialize
101  * @inum: inode number
102  */
103 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
104 				      ino_t inum)
105 {
106 	union ubifs_key *key = k;
107 
108 	key->j32[0] = cpu_to_le32(inum);
109 	key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
110 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
111 }
112 
113 /**
114  * lowest_ino_key - get the lowest possible inode key.
115  * @c: UBIFS file-system description object
116  * @key: key to initialize
117  * @inum: inode number
118  */
119 static inline void lowest_ino_key(const struct ubifs_info *c,
120 				union ubifs_key *key, ino_t inum)
121 {
122 	key->u32[0] = inum;
123 	key->u32[1] = 0;
124 }
125 
126 /**
127  * highest_ino_key - get the highest possible inode key.
128  * @c: UBIFS file-system description object
129  * @key: key to initialize
130  * @inum: inode number
131  */
132 static inline void highest_ino_key(const struct ubifs_info *c,
133 				union ubifs_key *key, ino_t inum)
134 {
135 	key->u32[0] = inum;
136 	key->u32[1] = 0xffffffff;
137 }
138 
139 /**
140  * dent_key_init - initialize directory entry key.
141  * @c: UBIFS file-system description object
142  * @key: key to initialize
143  * @inum: parent inode number
144  * @nm: direntry name and length. Not a string when encrypted!
145  */
146 static inline void dent_key_init(const struct ubifs_info *c,
147 				 union ubifs_key *key, ino_t inum,
148 				 const struct fscrypt_name *nm)
149 {
150 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
151 
152 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
153 	key->u32[0] = inum;
154 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
155 }
156 
157 /**
158  * dent_key_init_hash - initialize directory entry key without re-calculating
159  *                      hash function.
160  * @c: UBIFS file-system description object
161  * @key: key to initialize
162  * @inum: parent inode number
163  * @hash: direntry name hash
164  */
165 static inline void dent_key_init_hash(const struct ubifs_info *c,
166 				      union ubifs_key *key, ino_t inum,
167 				      uint32_t hash)
168 {
169 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
170 	key->u32[0] = inum;
171 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
172 }
173 
174 /**
175  * dent_key_init_flash - initialize on-flash directory entry key.
176  * @c: UBIFS file-system description object
177  * @k: key to initialize
178  * @inum: parent inode number
179  * @nm: direntry name and length
180  */
181 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
182 				       ino_t inum,
183 				       const struct fscrypt_name *nm)
184 {
185 	union ubifs_key *key = k;
186 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
187 
188 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
189 	key->j32[0] = cpu_to_le32(inum);
190 	key->j32[1] = cpu_to_le32(hash |
191 				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
192 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
193 }
194 
195 /**
196  * lowest_dent_key - get the lowest possible directory entry key.
197  * @c: UBIFS file-system description object
198  * @key: where to store the lowest key
199  * @inum: parent inode number
200  */
201 static inline void lowest_dent_key(const struct ubifs_info *c,
202 				   union ubifs_key *key, ino_t inum)
203 {
204 	key->u32[0] = inum;
205 	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
206 }
207 
208 /**
209  * xent_key_init - initialize extended attribute entry key.
210  * @c: UBIFS file-system description object
211  * @key: key to initialize
212  * @inum: host inode number
213  * @nm: extended attribute entry name and length
214  */
215 static inline void xent_key_init(const struct ubifs_info *c,
216 				 union ubifs_key *key, ino_t inum,
217 				 const struct fscrypt_name *nm)
218 {
219 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
220 
221 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
222 	key->u32[0] = inum;
223 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
224 }
225 
226 /**
227  * xent_key_init_flash - initialize on-flash extended attribute entry key.
228  * @c: UBIFS file-system description object
229  * @k: key to initialize
230  * @inum: host inode number
231  * @nm: extended attribute entry name and length
232  */
233 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
234 				       ino_t inum, const struct fscrypt_name *nm)
235 {
236 	union ubifs_key *key = k;
237 	uint32_t hash = c->key_hash(fname_name(nm), fname_len(nm));
238 
239 	ubifs_assert(c, !(hash & ~UBIFS_S_KEY_HASH_MASK));
240 	key->j32[0] = cpu_to_le32(inum);
241 	key->j32[1] = cpu_to_le32(hash |
242 				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
243 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
244 }
245 
246 /**
247  * lowest_xent_key - get the lowest possible extended attribute entry key.
248  * @c: UBIFS file-system description object
249  * @key: where to store the lowest key
250  * @inum: host inode number
251  */
252 static inline void lowest_xent_key(const struct ubifs_info *c,
253 				   union ubifs_key *key, ino_t inum)
254 {
255 	key->u32[0] = inum;
256 	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
257 }
258 
259 /**
260  * data_key_init - initialize data key.
261  * @c: UBIFS file-system description object
262  * @key: key to initialize
263  * @inum: inode number
264  * @block: block number
265  */
266 static inline void data_key_init(const struct ubifs_info *c,
267 				 union ubifs_key *key, ino_t inum,
268 				 unsigned int block)
269 {
270 	ubifs_assert(c, !(block & ~UBIFS_S_KEY_BLOCK_MASK));
271 	key->u32[0] = inum;
272 	key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
273 }
274 
275 /**
276  * highest_data_key - get the highest possible data key for an inode.
277  * @c: UBIFS file-system description object
278  * @key: key to initialize
279  * @inum: inode number
280  */
281 static inline void highest_data_key(const struct ubifs_info *c,
282 				   union ubifs_key *key, ino_t inum)
283 {
284 	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
285 }
286 
287 /**
288  * trun_key_init - initialize truncation node key.
289  * @c: UBIFS file-system description object
290  * @key: key to initialize
291  * @inum: inode number
292  *
293  * Note, UBIFS does not have truncation keys on the media and this function is
294  * only used for purposes of replay.
295  */
296 static inline void trun_key_init(const struct ubifs_info *c,
297 				 union ubifs_key *key, ino_t inum)
298 {
299 	key->u32[0] = inum;
300 	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
301 }
302 
303 /**
304  * invalid_key_init - initialize invalid node key.
305  * @c: UBIFS file-system description object
306  * @key: key to initialize
307  *
308  * This is a helper function which marks a @key object as invalid.
309  */
310 static inline void invalid_key_init(const struct ubifs_info *c,
311 				    union ubifs_key *key)
312 {
313 	key->u32[0] = 0xDEADBEAF;
314 	key->u32[1] = UBIFS_INVALID_KEY;
315 }
316 
317 /**
318  * key_type - get key type.
319  * @c: UBIFS file-system description object
320  * @key: key to get type of
321  */
322 static inline int key_type(const struct ubifs_info *c,
323 			   const union ubifs_key *key)
324 {
325 	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
326 }
327 
328 /**
329  * key_type_flash - get type of a on-flash formatted key.
330  * @c: UBIFS file-system description object
331  * @k: key to get type of
332  */
333 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
334 {
335 	const union ubifs_key *key = k;
336 
337 	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
338 }
339 
340 /**
341  * key_inum - fetch inode number from key.
342  * @c: UBIFS file-system description object
343  * @k: key to fetch inode number from
344  */
345 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
346 {
347 	const union ubifs_key *key = k;
348 
349 	return key->u32[0];
350 }
351 
352 /**
353  * key_inum_flash - fetch inode number from an on-flash formatted key.
354  * @c: UBIFS file-system description object
355  * @k: key to fetch inode number from
356  */
357 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
358 {
359 	const union ubifs_key *key = k;
360 
361 	return le32_to_cpu(key->j32[0]);
362 }
363 
364 /**
365  * key_hash - get directory entry hash.
366  * @c: UBIFS file-system description object
367  * @key: the key to get hash from
368  */
369 static inline uint32_t key_hash(const struct ubifs_info *c,
370 				const union ubifs_key *key)
371 {
372 	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
373 }
374 
375 /**
376  * key_hash_flash - get directory entry hash from an on-flash formatted key.
377  * @c: UBIFS file-system description object
378  * @k: the key to get hash from
379  */
380 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
381 {
382 	const union ubifs_key *key = k;
383 
384 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
385 }
386 
387 /**
388  * key_block - get data block number.
389  * @c: UBIFS file-system description object
390  * @key: the key to get the block number from
391  */
392 static inline unsigned int key_block(const struct ubifs_info *c,
393 				     const union ubifs_key *key)
394 {
395 	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
396 }
397 
398 /**
399  * key_block_flash - get data block number from an on-flash formatted key.
400  * @c: UBIFS file-system description object
401  * @k: the key to get the block number from
402  */
403 static inline unsigned int key_block_flash(const struct ubifs_info *c,
404 					   const void *k)
405 {
406 	const union ubifs_key *key = k;
407 
408 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
409 }
410 
411 /**
412  * key_read - transform a key to in-memory format.
413  * @c: UBIFS file-system description object
414  * @from: the key to transform
415  * @to: the key to store the result
416  */
417 static inline void key_read(const struct ubifs_info *c, const void *from,
418 			    union ubifs_key *to)
419 {
420 	const union ubifs_key *f = from;
421 
422 	to->u32[0] = le32_to_cpu(f->j32[0]);
423 	to->u32[1] = le32_to_cpu(f->j32[1]);
424 }
425 
426 /**
427  * key_write - transform a key from in-memory format.
428  * @c: UBIFS file-system description object
429  * @from: the key to transform
430  * @to: the key to store the result
431  */
432 static inline void key_write(const struct ubifs_info *c,
433 			     const union ubifs_key *from, void *to)
434 {
435 	union ubifs_key *t = to;
436 
437 	t->j32[0] = cpu_to_le32(from->u32[0]);
438 	t->j32[1] = cpu_to_le32(from->u32[1]);
439 	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
440 }
441 
442 /**
443  * key_write_idx - transform a key from in-memory format for the index.
444  * @c: UBIFS file-system description object
445  * @from: the key to transform
446  * @to: the key to store the result
447  */
448 static inline void key_write_idx(const struct ubifs_info *c,
449 				 const union ubifs_key *from, void *to)
450 {
451 	union ubifs_key *t = to;
452 
453 	t->j32[0] = cpu_to_le32(from->u32[0]);
454 	t->j32[1] = cpu_to_le32(from->u32[1]);
455 }
456 
457 /**
458  * key_copy - copy a key.
459  * @c: UBIFS file-system description object
460  * @from: the key to copy from
461  * @to: the key to copy to
462  */
463 static inline void key_copy(const struct ubifs_info *c,
464 			    const union ubifs_key *from, union ubifs_key *to)
465 {
466 	to->u64[0] = from->u64[0];
467 }
468 
469 /**
470  * keys_cmp - compare keys.
471  * @c: UBIFS file-system description object
472  * @key1: the first key to compare
473  * @key2: the second key to compare
474  *
475  * This function compares 2 keys and returns %-1 if @key1 is less than
476  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
477  */
478 static inline int keys_cmp(const struct ubifs_info *c,
479 			   const union ubifs_key *key1,
480 			   const union ubifs_key *key2)
481 {
482 	if (key1->u32[0] < key2->u32[0])
483 		return -1;
484 	if (key1->u32[0] > key2->u32[0])
485 		return 1;
486 	if (key1->u32[1] < key2->u32[1])
487 		return -1;
488 	if (key1->u32[1] > key2->u32[1])
489 		return 1;
490 
491 	return 0;
492 }
493 
494 /**
495  * keys_eq - determine if keys are equivalent.
496  * @c: UBIFS file-system description object
497  * @key1: the first key to compare
498  * @key2: the second key to compare
499  *
500  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
501  * %0 if not.
502  */
503 static inline int keys_eq(const struct ubifs_info *c,
504 			  const union ubifs_key *key1,
505 			  const union ubifs_key *key2)
506 {
507 	if (key1->u32[0] != key2->u32[0])
508 		return 0;
509 	if (key1->u32[1] != key2->u32[1])
510 		return 0;
511 	return 1;
512 }
513 
514 /**
515  * is_hash_key - is a key vulnerable to hash collisions.
516  * @c: UBIFS file-system description object
517  * @key: key
518  *
519  * This function returns %1 if @key is a hashed key or %0 otherwise.
520  */
521 static inline int is_hash_key(const struct ubifs_info *c,
522 			      const union ubifs_key *key)
523 {
524 	int type = key_type(c, key);
525 
526 	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
527 }
528 
529 /**
530  * key_max_inode_size - get maximum file size allowed by current key format.
531  * @c: UBIFS file-system description object
532  */
533 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
534 {
535 	switch (c->key_fmt) {
536 	case UBIFS_SIMPLE_KEY_FMT:
537 		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
538 	default:
539 		return 0;
540 	}
541 }
542 
543 #endif /* !__UBIFS_KEY_H__ */
544