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 /* This file implements reading and writing the master node */
12
13 #include "ubifs.h"
14
15 /**
16 * ubifs_compare_master_node - compare two UBIFS master nodes
17 * @c: UBIFS file-system description object
18 * @m1: the first node
19 * @m2: the second node
20 *
21 * This function compares two UBIFS master nodes. Returns 0 if they are equal
22 * and nonzero if not.
23 */
24 int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
25 {
26 int ret;
27 int behind;
28 int hmac_offs = offsetof(struct ubifs_mst_node, hmac);
29
30 /*
31 * Do not compare the common node header since the sequence number and
32 * hence the CRC are different.
33 */
34 ret = memcmp(m1 + UBIFS_CH_SZ, m2 + UBIFS_CH_SZ,
35 hmac_offs - UBIFS_CH_SZ);
36 if (ret)
37 return ret;
38
39 /*
40 * Do not compare the embedded HMAC as well which also must be different
41 * due to the different common node header.
42 */
43 behind = hmac_offs + UBIFS_MAX_HMAC_LEN;
44
45 if (UBIFS_MST_NODE_SZ > behind)
46 return memcmp(m1 + behind, m2 + behind, UBIFS_MST_NODE_SZ - behind);
47
48 return 0;
49 }
50
51 /* mst_node_check_hash - Check hash of a master node
52 * @c: UBIFS file-system description object
53 * @mst: The master node
54 * @expected: The expected hash of the master node
55 *
56 * This checks the hash of a master node against a given expected hash.
57 * Note that we have two master nodes on a UBIFS image which have different
58 * sequence numbers and consequently different CRCs. To be able to match
59 * both master nodes we exclude the common node header containing the sequence
60 * number and CRC from the hash.
61 *
62 * Returns 0 if the hashes are equal, a negative error code otherwise.
63 */
64 static int mst_node_check_hash(const struct ubifs_info *c,
65 const struct ubifs_mst_node *mst,
66 const u8 *expected)
67 {
68 u8 calc[UBIFS_MAX_HASH_LEN];
69 const void *node = mst;
70 int ret;
71
72 ret = crypto_shash_tfm_digest(c->hash_tfm, node + sizeof(struct ubifs_ch),
73 UBIFS_MST_NODE_SZ - sizeof(struct ubifs_ch),
74 calc);
75 if (ret)
76 return ret;
77
78 if (ubifs_check_hash(c, expected, calc))
79 return -EPERM;
80
81 return 0;
82 }
83
84 /**
85 * scan_for_master - search the valid master node.
86 * @c: UBIFS file-system description object
87 *
88 * This function scans the master node LEBs and search for the latest master
89 * node. Returns zero in case of success, %-EUCLEAN if there master area is
90 * corrupted and requires recovery, and a negative error code in case of
91 * failure.
92 */
93 static int scan_for_master(struct ubifs_info *c)
94 {
95 struct ubifs_scan_leb *sleb;
96 struct ubifs_scan_node *snod;
97 int lnum, offs = 0, nodes_cnt, err;
98
99 lnum = UBIFS_MST_LNUM;
100
101 sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
102 if (IS_ERR(sleb))
103 return PTR_ERR(sleb);
104 nodes_cnt = sleb->nodes_cnt;
105 if (nodes_cnt > 0) {
106 snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
107 list);
108 if (snod->type != UBIFS_MST_NODE)
109 goto out_dump;
110 memcpy(c->mst_node, snod->node, snod->len);
111 offs = snod->offs;
112 }
113 ubifs_scan_destroy(sleb);
114
115 lnum += 1;
116
117 sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
118 if (IS_ERR(sleb))
119 return PTR_ERR(sleb);
120 if (sleb->nodes_cnt != nodes_cnt)
121 goto out;
122 if (!sleb->nodes_cnt)
123 goto out;
124 snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node, list);
125 if (snod->type != UBIFS_MST_NODE)
126 goto out_dump;
127 if (snod->offs != offs)
128 goto out;
129 if (ubifs_compare_master_node(c, c->mst_node, snod->node))
130 goto out;
131
132 c->mst_offs = offs;
133 ubifs_scan_destroy(sleb);
134
135 if (!ubifs_authenticated(c))
136 return 0;
137
138 if (ubifs_hmac_zero(c, c->mst_node->hmac)) {
139 err = mst_node_check_hash(c, c->mst_node,
140 c->sup_node->hash_mst);
141 if (err)
142 ubifs_err(c, "Failed to verify master node hash");
143 } else {
144 err = ubifs_node_verify_hmac(c, c->mst_node,
145 sizeof(struct ubifs_mst_node),
146 offsetof(struct ubifs_mst_node, hmac));
147 if (err)
148 ubifs_err(c, "Failed to verify master node HMAC");
149 }
150
151 if (err)
152 return -EPERM;
153
154 return 0;
155
156 out:
157 ubifs_scan_destroy(sleb);
158 return -EUCLEAN;
159
160 out_dump:
161 ubifs_err(c, "unexpected node type %d master LEB %d:%d",
162 snod->type, lnum, snod->offs);
163 ubifs_scan_destroy(sleb);
164 return -EINVAL;
165 }
166
167 /**
168 * validate_master - validate master node.
169 * @c: UBIFS file-system description object
170 *
171 * This function validates data which was read from master node. Returns zero
172 * if the data is all right and %-EINVAL if not.
173 */
174 static int validate_master(const struct ubifs_info *c)
175 {
176 long long main_sz;
177 int err;
178
179 if (c->max_sqnum >= SQNUM_WATERMARK) {
180 err = 1;
181 goto out;
182 }
183
184 if (c->cmt_no >= c->max_sqnum) {
185 err = 2;
186 goto out;
187 }
188
189 if (c->highest_inum >= INUM_WATERMARK) {
190 err = 3;
191 goto out;
192 }
193
194 if (c->lhead_lnum < UBIFS_LOG_LNUM ||
195 c->lhead_lnum >= UBIFS_LOG_LNUM + c->log_lebs ||
196 c->lhead_offs < 0 || c->lhead_offs >= c->leb_size ||
197 c->lhead_offs & (c->min_io_size - 1)) {
198 err = 4;
199 goto out;
200 }
201
202 if (c->zroot.lnum >= c->leb_cnt || c->zroot.lnum < c->main_first ||
203 c->zroot.offs >= c->leb_size || c->zroot.offs & 7) {
204 err = 5;
205 goto out;
206 }
207
208 if (c->zroot.len < c->ranges[UBIFS_IDX_NODE].min_len ||
209 c->zroot.len > c->ranges[UBIFS_IDX_NODE].max_len) {
210 err = 6;
211 goto out;
212 }
213
214 if (c->gc_lnum >= c->leb_cnt || c->gc_lnum < c->main_first) {
215 err = 7;
216 goto out;
217 }
218
219 if (c->ihead_lnum >= c->leb_cnt || c->ihead_lnum < c->main_first ||
220 c->ihead_offs % c->min_io_size || c->ihead_offs < 0 ||
221 c->ihead_offs > c->leb_size || c->ihead_offs & 7) {
222 err = 8;
223 goto out;
224 }
225
226 main_sz = (long long)c->main_lebs * c->leb_size;
227 if (c->bi.old_idx_sz & 7 || c->bi.old_idx_sz >= main_sz) {
228 err = 9;
229 goto out;
230 }
231
232 if (c->lpt_lnum < c->lpt_first || c->lpt_lnum > c->lpt_last ||
233 c->lpt_offs < 0 || c->lpt_offs + c->nnode_sz > c->leb_size) {
234 err = 10;
235 goto out;
236 }
237
238 if (c->nhead_lnum < c->lpt_first || c->nhead_lnum > c->lpt_last ||
239 c->nhead_offs < 0 || c->nhead_offs % c->min_io_size ||
240 c->nhead_offs > c->leb_size) {
241 err = 11;
242 goto out;
243 }
244
245 if (c->ltab_lnum < c->lpt_first || c->ltab_lnum > c->lpt_last ||
246 c->ltab_offs < 0 ||
247 c->ltab_offs + c->ltab_sz > c->leb_size) {
248 err = 12;
249 goto out;
250 }
251
252 if (c->big_lpt && (c->lsave_lnum < c->lpt_first ||
253 c->lsave_lnum > c->lpt_last || c->lsave_offs < 0 ||
254 c->lsave_offs + c->lsave_sz > c->leb_size)) {
255 err = 13;
256 goto out;
257 }
258
259 if (c->lscan_lnum < c->main_first || c->lscan_lnum >= c->leb_cnt) {
260 err = 14;
261 goto out;
262 }
263
264 if (c->lst.empty_lebs < 0 || c->lst.empty_lebs > c->main_lebs - 2) {
265 err = 15;
266 goto out;
267 }
268
269 if (c->lst.idx_lebs < 0 || c->lst.idx_lebs > c->main_lebs - 1) {
270 err = 16;
271 goto out;
272 }
273
274 if (c->lst.total_free < 0 || c->lst.total_free > main_sz ||
275 c->lst.total_free & 7) {
276 err = 17;
277 goto out;
278 }
279
280 if (c->lst.total_dirty < 0 || (c->lst.total_dirty & 7)) {
281 err = 18;
282 goto out;
283 }
284
285 if (c->lst.total_used < 0 || (c->lst.total_used & 7)) {
286 err = 19;
287 goto out;
288 }
289
290 if (c->lst.total_free + c->lst.total_dirty +
291 c->lst.total_used > main_sz) {
292 err = 20;
293 goto out;
294 }
295
296 if (c->lst.total_dead + c->lst.total_dark +
297 c->lst.total_used + c->bi.old_idx_sz > main_sz) {
298 err = 21;
299 goto out;
300 }
301
302 if (c->lst.total_dead < 0 ||
303 c->lst.total_dead > c->lst.total_free + c->lst.total_dirty ||
304 c->lst.total_dead & 7) {
305 err = 22;
306 goto out;
307 }
308
309 if (c->lst.total_dark < 0 ||
310 c->lst.total_dark > c->lst.total_free + c->lst.total_dirty ||
311 c->lst.total_dark & 7) {
312 err = 23;
313 goto out;
314 }
315
316 return 0;
317
318 out:
319 ubifs_err(c, "bad master node at offset %d error %d", c->mst_offs, err);
320 ubifs_dump_node(c, c->mst_node, c->mst_node_alsz);
321 return -EINVAL;
322 }
323
324 /**
325 * ubifs_read_master - read master node.
326 * @c: UBIFS file-system description object
327 *
328 * This function finds and reads the master node during file-system mount. If
329 * the flash is empty, it creates default master node as well. Returns zero in
330 * case of success and a negative error code in case of failure.
331 */
332 int ubifs_read_master(struct ubifs_info *c)
333 {
334 int err, old_leb_cnt;
335
336 c->mst_node = kzalloc(c->mst_node_alsz, GFP_KERNEL);
337 if (!c->mst_node)
338 return -ENOMEM;
339
340 err = scan_for_master(c);
341 if (err) {
342 if (err == -EUCLEAN)
343 err = ubifs_recover_master_node(c);
344 if (err)
345 /*
346 * Note, we do not free 'c->mst_node' here because the
347 * unmount routine will take care of this.
348 */
349 return err;
350 }
351
352 /* Make sure that the recovery flag is clear */
353 c->mst_node->flags &= cpu_to_le32(~UBIFS_MST_RCVRY);
354
355 c->max_sqnum = le64_to_cpu(c->mst_node->ch.sqnum);
356 c->highest_inum = le64_to_cpu(c->mst_node->highest_inum);
357 c->cmt_no = le64_to_cpu(c->mst_node->cmt_no);
358 c->zroot.lnum = le32_to_cpu(c->mst_node->root_lnum);
359 c->zroot.offs = le32_to_cpu(c->mst_node->root_offs);
360 c->zroot.len = le32_to_cpu(c->mst_node->root_len);
361 c->lhead_lnum = le32_to_cpu(c->mst_node->log_lnum);
362 c->gc_lnum = le32_to_cpu(c->mst_node->gc_lnum);
363 c->ihead_lnum = le32_to_cpu(c->mst_node->ihead_lnum);
364 c->ihead_offs = le32_to_cpu(c->mst_node->ihead_offs);
365 c->bi.old_idx_sz = le64_to_cpu(c->mst_node->index_size);
366 c->lpt_lnum = le32_to_cpu(c->mst_node->lpt_lnum);
367 c->lpt_offs = le32_to_cpu(c->mst_node->lpt_offs);
368 c->nhead_lnum = le32_to_cpu(c->mst_node->nhead_lnum);
369 c->nhead_offs = le32_to_cpu(c->mst_node->nhead_offs);
370 c->ltab_lnum = le32_to_cpu(c->mst_node->ltab_lnum);
371 c->ltab_offs = le32_to_cpu(c->mst_node->ltab_offs);
372 c->lsave_lnum = le32_to_cpu(c->mst_node->lsave_lnum);
373 c->lsave_offs = le32_to_cpu(c->mst_node->lsave_offs);
374 c->lscan_lnum = le32_to_cpu(c->mst_node->lscan_lnum);
375 c->lst.empty_lebs = le32_to_cpu(c->mst_node->empty_lebs);
376 c->lst.idx_lebs = le32_to_cpu(c->mst_node->idx_lebs);
377 old_leb_cnt = le32_to_cpu(c->mst_node->leb_cnt);
378 c->lst.total_free = le64_to_cpu(c->mst_node->total_free);
379 c->lst.total_dirty = le64_to_cpu(c->mst_node->total_dirty);
380 c->lst.total_used = le64_to_cpu(c->mst_node->total_used);
381 c->lst.total_dead = le64_to_cpu(c->mst_node->total_dead);
382 c->lst.total_dark = le64_to_cpu(c->mst_node->total_dark);
383
384 ubifs_copy_hash(c, c->mst_node->hash_root_idx, c->zroot.hash);
385
386 c->calc_idx_sz = c->bi.old_idx_sz;
387
388 if (c->mst_node->flags & cpu_to_le32(UBIFS_MST_NO_ORPHS))
389 c->no_orphs = 1;
390
391 if (old_leb_cnt != c->leb_cnt) {
392 /* The file system has been resized */
393 int growth = c->leb_cnt - old_leb_cnt;
394
395 if (c->leb_cnt < old_leb_cnt ||
396 c->leb_cnt < UBIFS_MIN_LEB_CNT) {
397 ubifs_err(c, "bad leb_cnt on master node");
398 ubifs_dump_node(c, c->mst_node, c->mst_node_alsz);
399 return -EINVAL;
400 }
401
402 dbg_mnt("Auto resizing (master) from %d LEBs to %d LEBs",
403 old_leb_cnt, c->leb_cnt);
404 c->lst.empty_lebs += growth;
405 c->lst.total_free += growth * (long long)c->leb_size;
406 c->lst.total_dark += growth * (long long)c->dark_wm;
407
408 /*
409 * Reflect changes back onto the master node. N.B. the master
410 * node gets written immediately whenever mounting (or
411 * remounting) in read-write mode, so we do not need to write it
412 * here.
413 */
414 c->mst_node->leb_cnt = cpu_to_le32(c->leb_cnt);
415 c->mst_node->empty_lebs = cpu_to_le32(c->lst.empty_lebs);
416 c->mst_node->total_free = cpu_to_le64(c->lst.total_free);
417 c->mst_node->total_dark = cpu_to_le64(c->lst.total_dark);
418 }
419
420 err = validate_master(c);
421 if (err)
422 return err;
423
424 err = dbg_old_index_check_init(c, &c->zroot);
425
426 return err;
427 }
428
429 /**
430 * ubifs_write_master - write master node.
431 * @c: UBIFS file-system description object
432 *
433 * This function writes the master node. Returns zero in case of success and a
434 * negative error code in case of failure. The master node is written twice to
435 * enable recovery.
436 */
437 int ubifs_write_master(struct ubifs_info *c)
438 {
439 int err, lnum, offs, len;
440
441 ubifs_assert(c, !c->ro_media && !c->ro_mount);
442 if (c->ro_error)
443 return -EROFS;
444
445 lnum = UBIFS_MST_LNUM;
446 offs = c->mst_offs + c->mst_node_alsz;
447 len = UBIFS_MST_NODE_SZ;
448
449 if (offs + UBIFS_MST_NODE_SZ > c->leb_size) {
450 err = ubifs_leb_unmap(c, lnum);
451 if (err)
452 return err;
453 offs = 0;
454 }
455
456 c->mst_offs = offs;
457 c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);
458
459 ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);
460 err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
461 offsetof(struct ubifs_mst_node, hmac));
462 if (err)
463 return err;
464
465 lnum += 1;
466
467 if (offs == 0) {
468 err = ubifs_leb_unmap(c, lnum);
469 if (err)
470 return err;
471 }
472 err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
473 offsetof(struct ubifs_mst_node, hmac));
474
475 return err;
476 }
477
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