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: Adrian Hunter
8  *          Artem Bityutskiy (Битюцкий Артём)
9  */
10 
11 /*
12  * This file contains miscelanious TNC-related functions shared betweend
13  * different files. This file does not form any logically separate TNC
14  * sub-system. The file was created because there is a lot of TNC code and
15  * putting it all in one file would make that file too big and unreadable.
16  */
17 
18 #include "ubifs.h"
19 
20 /**
21  * ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
22  * @c: UBIFS file-system description object
23  * @zr: root of the subtree to traverse
24  * @znode: previous znode
25  *
26  * This function implements levelorder TNC traversal. The LNC is ignored.
27  * Returns the next element or %NULL if @znode is already the last one.
28  */
ubifs_tnc_levelorder_next(const struct ubifs_info * c,struct ubifs_znode * zr,struct ubifs_znode * znode)29 struct ubifs_znode *ubifs_tnc_levelorder_next(const struct ubifs_info *c,
30 					      struct ubifs_znode *zr,
31 					      struct ubifs_znode *znode)
32 {
33 	int level, iip, level_search = 0;
34 	struct ubifs_znode *zn;
35 
36 	ubifs_assert(c, zr);
37 
38 	if (unlikely(!znode))
39 		return zr;
40 
41 	if (unlikely(znode == zr)) {
42 		if (znode->level == 0)
43 			return NULL;
44 		return ubifs_tnc_find_child(zr, 0);
45 	}
46 
47 	level = znode->level;
48 
49 	iip = znode->iip;
50 	while (1) {
51 		ubifs_assert(c, znode->level <= zr->level);
52 
53 		/*
54 		 * First walk up until there is a znode with next branch to
55 		 * look at.
56 		 */
57 		while (znode->parent != zr && iip >= znode->parent->child_cnt) {
58 			znode = znode->parent;
59 			iip = znode->iip;
60 		}
61 
62 		if (unlikely(znode->parent == zr &&
63 			     iip >= znode->parent->child_cnt)) {
64 			/* This level is done, switch to the lower one */
65 			level -= 1;
66 			if (level_search || level < 0)
67 				/*
68 				 * We were already looking for znode at lower
69 				 * level ('level_search'). As we are here
70 				 * again, it just does not exist. Or all levels
71 				 * were finished ('level < 0').
72 				 */
73 				return NULL;
74 
75 			level_search = 1;
76 			iip = -1;
77 			znode = ubifs_tnc_find_child(zr, 0);
78 			ubifs_assert(c, znode);
79 		}
80 
81 		/* Switch to the next index */
82 		zn = ubifs_tnc_find_child(znode->parent, iip + 1);
83 		if (!zn) {
84 			/* No more children to look at, we have walk up */
85 			iip = znode->parent->child_cnt;
86 			continue;
87 		}
88 
89 		/* Walk back down to the level we came from ('level') */
90 		while (zn->level != level) {
91 			znode = zn;
92 			zn = ubifs_tnc_find_child(zn, 0);
93 			if (!zn) {
94 				/*
95 				 * This path is not too deep so it does not
96 				 * reach 'level'. Try next path.
97 				 */
98 				iip = znode->iip;
99 				break;
100 			}
101 		}
102 
103 		if (zn) {
104 			ubifs_assert(c, zn->level >= 0);
105 			return zn;
106 		}
107 	}
108 }
109 
110 /**
111  * ubifs_search_zbranch - search znode branch.
112  * @c: UBIFS file-system description object
113  * @znode: znode to search in
114  * @key: key to search for
115  * @n: znode branch slot number is returned here
116  *
117  * This is a helper function which search branch with key @key in @znode using
118  * binary search. The result of the search may be:
119  *   o exact match, then %1 is returned, and the slot number of the branch is
120  *     stored in @n;
121  *   o no exact match, then %0 is returned and the slot number of the left
122  *     closest branch is returned in @n; the slot if all keys in this znode are
123  *     greater than @key, then %-1 is returned in @n.
124  */
ubifs_search_zbranch(const struct ubifs_info * c,const struct ubifs_znode * znode,const union ubifs_key * key,int * n)125 int ubifs_search_zbranch(const struct ubifs_info *c,
126 			 const struct ubifs_znode *znode,
127 			 const union ubifs_key *key, int *n)
128 {
129 	int beg = 0, end = znode->child_cnt, mid;
130 	int cmp;
131 	const struct ubifs_zbranch *zbr = &znode->zbranch[0];
132 
133 	ubifs_assert(c, end > beg);
134 
135 	while (end > beg) {
136 		mid = (beg + end) >> 1;
137 		cmp = keys_cmp(c, key, &zbr[mid].key);
138 		if (cmp > 0)
139 			beg = mid + 1;
140 		else if (cmp < 0)
141 			end = mid;
142 		else {
143 			*n = mid;
144 			return 1;
145 		}
146 	}
147 
148 	*n = end - 1;
149 
150 	/* The insert point is after *n */
151 	ubifs_assert(c, *n >= -1 && *n < znode->child_cnt);
152 	if (*n == -1)
153 		ubifs_assert(c, keys_cmp(c, key, &zbr[0].key) < 0);
154 	else
155 		ubifs_assert(c, keys_cmp(c, key, &zbr[*n].key) > 0);
156 	if (*n + 1 < znode->child_cnt)
157 		ubifs_assert(c, keys_cmp(c, key, &zbr[*n + 1].key) < 0);
158 
159 	return 0;
160 }
161 
162 /**
163  * ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
164  * @znode: znode to start at (root of the sub-tree to traverse)
165  *
166  * Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
167  * ignored.
168  */
ubifs_tnc_postorder_first(struct ubifs_znode * znode)169 struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
170 {
171 	if (unlikely(!znode))
172 		return NULL;
173 
174 	while (znode->level > 0) {
175 		struct ubifs_znode *child;
176 
177 		child = ubifs_tnc_find_child(znode, 0);
178 		if (!child)
179 			return znode;
180 		znode = child;
181 	}
182 
183 	return znode;
184 }
185 
186 /**
187  * ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
188  * @c: UBIFS file-system description object
189  * @znode: previous znode
190  *
191  * This function implements postorder TNC traversal. The LNC is ignored.
192  * Returns the next element or %NULL if @znode is already the last one.
193  */
ubifs_tnc_postorder_next(const struct ubifs_info * c,struct ubifs_znode * znode)194 struct ubifs_znode *ubifs_tnc_postorder_next(const struct ubifs_info *c,
195 					     struct ubifs_znode *znode)
196 {
197 	struct ubifs_znode *zn;
198 
199 	ubifs_assert(c, znode);
200 	if (unlikely(!znode->parent))
201 		return NULL;
202 
203 	/* Switch to the next index in the parent */
204 	zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
205 	if (!zn)
206 		/* This is in fact the last child, return parent */
207 		return znode->parent;
208 
209 	/* Go to the first znode in this new subtree */
210 	return ubifs_tnc_postorder_first(zn);
211 }
212 
213 /**
214  * ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
215  * @c: UBIFS file-system description object
216  * @znode: znode defining subtree to destroy
217  *
218  * This function destroys subtree of the TNC tree. Returns number of clean
219  * znodes in the subtree.
220  */
ubifs_destroy_tnc_subtree(const struct ubifs_info * c,struct ubifs_znode * znode)221 long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
222 			       struct ubifs_znode *znode)
223 {
224 	struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
225 	long clean_freed = 0;
226 	int n;
227 
228 	ubifs_assert(c, zn);
229 	while (1) {
230 		for (n = 0; n < zn->child_cnt; n++) {
231 			if (!zn->zbranch[n].znode)
232 				continue;
233 
234 			if (zn->level > 0 &&
235 			    !ubifs_zn_dirty(zn->zbranch[n].znode))
236 				clean_freed += 1;
237 
238 			cond_resched();
239 			kfree(zn->zbranch[n].znode);
240 		}
241 
242 		if (zn == znode) {
243 			if (!ubifs_zn_dirty(zn))
244 				clean_freed += 1;
245 			kfree(zn);
246 			return clean_freed;
247 		}
248 
249 		zn = ubifs_tnc_postorder_next(c, zn);
250 	}
251 }
252 
253 /**
254  * read_znode - read an indexing node from flash and fill znode.
255  * @c: UBIFS file-system description object
256  * @zzbr: the zbranch describing the node to read
257  * @znode: znode to read to
258  *
259  * This function reads an indexing node from the flash media and fills znode
260  * with the read data. Returns zero in case of success and a negative error
261  * code in case of failure. The read indexing node is validated and if anything
262  * is wrong with it, this function prints complaint messages and returns
263  * %-EINVAL.
264  */
read_znode(struct ubifs_info * c,struct ubifs_zbranch * zzbr,struct ubifs_znode * znode)265 static int read_znode(struct ubifs_info *c, struct ubifs_zbranch *zzbr,
266 		      struct ubifs_znode *znode)
267 {
268 	int lnum = zzbr->lnum;
269 	int offs = zzbr->offs;
270 	int len = zzbr->len;
271 	int i, err, type, cmp;
272 	struct ubifs_idx_node *idx;
273 
274 	idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
275 	if (!idx)
276 		return -ENOMEM;
277 
278 	err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
279 	if (err < 0) {
280 		kfree(idx);
281 		return err;
282 	}
283 
284 	err = ubifs_node_check_hash(c, idx, zzbr->hash);
285 	if (err) {
286 		ubifs_bad_hash(c, idx, zzbr->hash, lnum, offs);
287 		kfree(idx);
288 		return err;
289 	}
290 
291 	znode->child_cnt = le16_to_cpu(idx->child_cnt);
292 	znode->level = le16_to_cpu(idx->level);
293 
294 	dbg_tnc("LEB %d:%d, level %d, %d branch",
295 		lnum, offs, znode->level, znode->child_cnt);
296 
297 	if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
298 		ubifs_err(c, "current fanout %d, branch count %d",
299 			  c->fanout, znode->child_cnt);
300 		ubifs_err(c, "max levels %d, znode level %d",
301 			  UBIFS_MAX_LEVELS, znode->level);
302 		err = 1;
303 		goto out_dump;
304 	}
305 
306 	for (i = 0; i < znode->child_cnt; i++) {
307 		struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
308 		struct ubifs_zbranch *zbr = &znode->zbranch[i];
309 
310 		key_read(c, &br->key, &zbr->key);
311 		zbr->lnum = le32_to_cpu(br->lnum);
312 		zbr->offs = le32_to_cpu(br->offs);
313 		zbr->len  = le32_to_cpu(br->len);
314 		ubifs_copy_hash(c, ubifs_branch_hash(c, br), zbr->hash);
315 		zbr->znode = NULL;
316 
317 		/* Validate branch */
318 
319 		if (zbr->lnum < c->main_first ||
320 		    zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
321 		    zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
322 			ubifs_err(c, "bad branch %d", i);
323 			err = 2;
324 			goto out_dump;
325 		}
326 
327 		switch (key_type(c, &zbr->key)) {
328 		case UBIFS_INO_KEY:
329 		case UBIFS_DATA_KEY:
330 		case UBIFS_DENT_KEY:
331 		case UBIFS_XENT_KEY:
332 			break;
333 		default:
334 			ubifs_err(c, "bad key type at slot %d: %d",
335 				  i, key_type(c, &zbr->key));
336 			err = 3;
337 			goto out_dump;
338 		}
339 
340 		if (znode->level)
341 			continue;
342 
343 		type = key_type(c, &zbr->key);
344 		if (c->ranges[type].max_len == 0) {
345 			if (zbr->len != c->ranges[type].len) {
346 				ubifs_err(c, "bad target node (type %d) length (%d)",
347 					  type, zbr->len);
348 				ubifs_err(c, "have to be %d", c->ranges[type].len);
349 				err = 4;
350 				goto out_dump;
351 			}
352 		} else if (zbr->len < c->ranges[type].min_len ||
353 			   zbr->len > c->ranges[type].max_len) {
354 			ubifs_err(c, "bad target node (type %d) length (%d)",
355 				  type, zbr->len);
356 			ubifs_err(c, "have to be in range of %d-%d",
357 				  c->ranges[type].min_len,
358 				  c->ranges[type].max_len);
359 			err = 5;
360 			goto out_dump;
361 		}
362 	}
363 
364 	/*
365 	 * Ensure that the next key is greater or equivalent to the
366 	 * previous one.
367 	 */
368 	for (i = 0; i < znode->child_cnt - 1; i++) {
369 		const union ubifs_key *key1, *key2;
370 
371 		key1 = &znode->zbranch[i].key;
372 		key2 = &znode->zbranch[i + 1].key;
373 
374 		cmp = keys_cmp(c, key1, key2);
375 		if (cmp > 0) {
376 			ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
377 			err = 6;
378 			goto out_dump;
379 		} else if (cmp == 0 && !is_hash_key(c, key1)) {
380 			/* These can only be keys with colliding hash */
381 			ubifs_err(c, "keys %d and %d are not hashed but equivalent",
382 				  i, i + 1);
383 			err = 7;
384 			goto out_dump;
385 		}
386 	}
387 
388 	kfree(idx);
389 	return 0;
390 
391 out_dump:
392 	ubifs_err(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
393 	ubifs_dump_node(c, idx, c->max_idx_node_sz);
394 	kfree(idx);
395 	return -EINVAL;
396 }
397 
398 /**
399  * ubifs_load_znode - load znode to TNC cache.
400  * @c: UBIFS file-system description object
401  * @zbr: znode branch
402  * @parent: znode's parent
403  * @iip: index in parent
404  *
405  * This function loads znode pointed to by @zbr into the TNC cache and
406  * returns pointer to it in case of success and a negative error code in case
407  * of failure.
408  */
ubifs_load_znode(struct ubifs_info * c,struct ubifs_zbranch * zbr,struct ubifs_znode * parent,int iip)409 struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
410 				     struct ubifs_zbranch *zbr,
411 				     struct ubifs_znode *parent, int iip)
412 {
413 	int err;
414 	struct ubifs_znode *znode;
415 
416 	ubifs_assert(c, !zbr->znode);
417 	/*
418 	 * A slab cache is not presently used for znodes because the znode size
419 	 * depends on the fanout which is stored in the superblock.
420 	 */
421 	znode = kzalloc(c->max_znode_sz, GFP_NOFS);
422 	if (!znode)
423 		return ERR_PTR(-ENOMEM);
424 
425 	err = read_znode(c, zbr, znode);
426 	if (err)
427 		goto out;
428 
429 	atomic_long_inc(&c->clean_zn_cnt);
430 
431 	/*
432 	 * Increment the global clean znode counter as well. It is OK that
433 	 * global and per-FS clean znode counters may be inconsistent for some
434 	 * short time (because we might be preempted at this point), the global
435 	 * one is only used in shrinker.
436 	 */
437 	atomic_long_inc(&ubifs_clean_zn_cnt);
438 
439 	zbr->znode = znode;
440 	znode->parent = parent;
441 	znode->time = ktime_get_seconds();
442 	znode->iip = iip;
443 
444 	return znode;
445 
446 out:
447 	kfree(znode);
448 	return ERR_PTR(err);
449 }
450 
451 /**
452  * ubifs_tnc_read_node - read a leaf node from the flash media.
453  * @c: UBIFS file-system description object
454  * @zbr: key and position of the node
455  * @node: node is returned here
456  *
457  * This function reads a node defined by @zbr from the flash media. Returns
458  * zero in case of success or a negative error code in case of failure.
459  */
ubifs_tnc_read_node(struct ubifs_info * c,struct ubifs_zbranch * zbr,void * node)460 int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
461 			void *node)
462 {
463 	union ubifs_key key1, *key = &zbr->key;
464 	int err, type = key_type(c, key);
465 	struct ubifs_wbuf *wbuf;
466 
467 	/*
468 	 * 'zbr' has to point to on-flash node. The node may sit in a bud and
469 	 * may even be in a write buffer, so we have to take care about this.
470 	 */
471 	wbuf = ubifs_get_wbuf(c, zbr->lnum);
472 	if (wbuf)
473 		err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
474 					   zbr->lnum, zbr->offs);
475 	else
476 		err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
477 				      zbr->offs);
478 
479 	if (err) {
480 		dbg_tnck(key, "key ");
481 		return err;
482 	}
483 
484 	/* Make sure the key of the read node is correct */
485 	key_read(c, node + UBIFS_KEY_OFFSET, &key1);
486 	if (!keys_eq(c, key, &key1)) {
487 		ubifs_err(c, "bad key in node at LEB %d:%d",
488 			  zbr->lnum, zbr->offs);
489 		dbg_tnck(key, "looked for key ");
490 		dbg_tnck(&key1, "but found node's key ");
491 		ubifs_dump_node(c, node, zbr->len);
492 		return -EINVAL;
493 	}
494 
495 	err = ubifs_node_check_hash(c, node, zbr->hash);
496 	if (err) {
497 		ubifs_bad_hash(c, node, zbr->hash, zbr->lnum, zbr->offs);
498 		return err;
499 	}
500 
501 	return 0;
502 }
503