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 (���������������� ����������)
9 */
10
11/*
12 * This file implements the scan which is a general-purpose function for
13 * determining what nodes are in an eraseblock. The scan is used to replay the
14 * journal, to do garbage collection. for the TNC in-the-gaps method, and by
15 * debugging functions.
16 */
17
18#include "ubifs.h"
19
20/**
21 * scan_padding_bytes - scan for padding bytes.
22 * @buf: buffer to scan
23 * @len: length of buffer
24 *
25 * This function returns the number of padding bytes on success and
26 * %SCANNED_GARBAGE on failure.
27 */
28static int scan_padding_bytes(void *buf, int len)
29{
30	int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
31	uint8_t *p = buf;
32
33	dbg_scan("not a node");
34
35	while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
36		pad_len += 1;
37
38	if (!pad_len || (pad_len & 7))
39		return SCANNED_GARBAGE;
40
41	dbg_scan("%d padding bytes", pad_len);
42
43	return pad_len;
44}
45
46/**
47 * ubifs_scan_a_node - scan for a node or padding.
48 * @c: UBIFS file-system description object
49 * @buf: buffer to scan
50 * @len: length of buffer
51 * @lnum: logical eraseblock number
52 * @offs: offset within the logical eraseblock
53 * @quiet: print no messages
54 *
55 * This function returns a scanning code to indicate what was scanned.
56 */
57int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
58		      int offs, int quiet)
59{
60	struct ubifs_ch *ch = buf;
61	uint32_t magic;
62
63	magic = le32_to_cpu(ch->magic);
64
65	if (magic == 0xFFFFFFFF) {
66		dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
67		return SCANNED_EMPTY_SPACE;
68	}
69
70	if (magic != UBIFS_NODE_MAGIC)
71		return scan_padding_bytes(buf, len);
72
73	if (len < UBIFS_CH_SZ)
74		return SCANNED_GARBAGE;
75
76	dbg_scan("scanning %s at LEB %d:%d",
77		 dbg_ntype(ch->node_type), lnum, offs);
78
79	if (ubifs_check_node(c, buf, len, lnum, offs, quiet, 1))
80		return SCANNED_A_CORRUPT_NODE;
81
82	if (ch->node_type == UBIFS_PAD_NODE) {
83		struct ubifs_pad_node *pad = buf;
84		int pad_len = le32_to_cpu(pad->pad_len);
85		int node_len = le32_to_cpu(ch->len);
86
87		/* Validate the padding node */
88		if (pad_len < 0 ||
89		    offs + node_len + pad_len > c->leb_size) {
90			if (!quiet) {
91				ubifs_err(c, "bad pad node at LEB %d:%d",
92					  lnum, offs);
93				ubifs_dump_node(c, pad, len);
94			}
95			return SCANNED_A_BAD_PAD_NODE;
96		}
97
98		/* Make the node pads to 8-byte boundary */
99		if ((node_len + pad_len) & 7) {
100			if (!quiet)
101				ubifs_err(c, "bad padding length %d - %d",
102					  offs, offs + node_len + pad_len);
103			return SCANNED_A_BAD_PAD_NODE;
104		}
105
106		dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
107			 lnum, offs, ALIGN(offs + node_len + pad_len, 8));
108
109		return node_len + pad_len;
110	}
111
112	return SCANNED_A_NODE;
113}
114
115/**
116 * ubifs_start_scan - create LEB scanning information at start of scan.
117 * @c: UBIFS file-system description object
118 * @lnum: logical eraseblock number
119 * @offs: offset to start at (usually zero)
120 * @sbuf: scan buffer (must be c->leb_size)
121 *
122 * This function returns the scanned information on success and a negative error
123 * code on failure.
124 */
125struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
126					int offs, void *sbuf)
127{
128	struct ubifs_scan_leb *sleb;
129	int err;
130
131	dbg_scan("scan LEB %d:%d", lnum, offs);
132
133	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
134	if (!sleb)
135		return ERR_PTR(-ENOMEM);
136
137	sleb->lnum = lnum;
138	INIT_LIST_HEAD(&sleb->nodes);
139	sleb->buf = sbuf;
140
141	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
142	if (err && err != -EBADMSG) {
143		ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
144			  c->leb_size - offs, lnum, offs, err);
145		kfree(sleb);
146		return ERR_PTR(err);
147	}
148
149	/*
150	 * Note, we ignore integrity errors (EBASMSG) because all the nodes are
151	 * protected by CRC checksums.
152	 */
153	return sleb;
154}
155
156/**
157 * ubifs_end_scan - update LEB scanning information at end of scan.
158 * @c: UBIFS file-system description object
159 * @sleb: scanning information
160 * @lnum: logical eraseblock number
161 * @offs: offset to start at (usually zero)
162 */
163void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
164		    int lnum, int offs)
165{
166	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
167	ubifs_assert(c, offs % c->min_io_size == 0);
168
169	sleb->endpt = ALIGN(offs, c->min_io_size);
170}
171
172/**
173 * ubifs_add_snod - add a scanned node to LEB scanning information.
174 * @c: UBIFS file-system description object
175 * @sleb: scanning information
176 * @buf: buffer containing node
177 * @offs: offset of node on flash
178 *
179 * This function returns %0 on success and a negative error code on failure.
180 */
181int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
182		   void *buf, int offs)
183{
184	struct ubifs_ch *ch = buf;
185	struct ubifs_ino_node *ino = buf;
186	struct ubifs_scan_node *snod;
187
188	snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
189	if (!snod)
190		return -ENOMEM;
191
192	snod->sqnum = le64_to_cpu(ch->sqnum);
193	snod->type = ch->node_type;
194	snod->offs = offs;
195	snod->len = le32_to_cpu(ch->len);
196	snod->node = buf;
197
198	switch (ch->node_type) {
199	case UBIFS_INO_NODE:
200	case UBIFS_DENT_NODE:
201	case UBIFS_XENT_NODE:
202	case UBIFS_DATA_NODE:
203		/*
204		 * The key is in the same place in all keyed
205		 * nodes.
206		 */
207		key_read(c, &ino->key, &snod->key);
208		break;
209	default:
210		invalid_key_init(c, &snod->key);
211		break;
212	}
213	list_add_tail(&snod->list, &sleb->nodes);
214	sleb->nodes_cnt += 1;
215	return 0;
216}
217
218/**
219 * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
220 * @c: UBIFS file-system description object
221 * @lnum: LEB number of corruption
222 * @offs: offset of corruption
223 * @buf: buffer containing corruption
224 */
225void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
226			      void *buf)
227{
228	int len;
229
230	ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
231	len = c->leb_size - offs;
232	if (len > 8192)
233		len = 8192;
234	ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
235	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
236}
237
238/**
239 * ubifs_scan - scan a logical eraseblock.
240 * @c: UBIFS file-system description object
241 * @lnum: logical eraseblock number
242 * @offs: offset to start at (usually zero)
243 * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
244 * @quiet: print no messages
245 *
246 * This function scans LEB number @lnum and returns complete information about
247 * its contents. Returns the scanned information in case of success and,
248 * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
249 * of failure.
250 *
251 * If @quiet is non-zero, this function does not print large and scary
252 * error messages and flash dumps in case of errors.
253 */
254struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
255				  int offs, void *sbuf, int quiet)
256{
257	void *buf = sbuf + offs;
258	int err, len = c->leb_size - offs;
259	struct ubifs_scan_leb *sleb;
260
261	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
262	if (IS_ERR(sleb))
263		return sleb;
264
265	while (len >= 8) {
266		struct ubifs_ch *ch = buf;
267		int node_len, ret;
268
269		dbg_scan("look at LEB %d:%d (%d bytes left)",
270			 lnum, offs, len);
271
272		cond_resched();
273
274		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
275		if (ret > 0) {
276			/* Padding bytes or a valid padding node */
277			offs += ret;
278			buf += ret;
279			len -= ret;
280			continue;
281		}
282
283		if (ret == SCANNED_EMPTY_SPACE)
284			/* Empty space is checked later */
285			break;
286
287		switch (ret) {
288		case SCANNED_GARBAGE:
289			ubifs_err(c, "garbage");
290			goto corrupted;
291		case SCANNED_A_NODE:
292			break;
293		case SCANNED_A_CORRUPT_NODE:
294		case SCANNED_A_BAD_PAD_NODE:
295			ubifs_err(c, "bad node");
296			goto corrupted;
297		default:
298			ubifs_err(c, "unknown");
299			err = -EINVAL;
300			goto error;
301		}
302
303		err = ubifs_add_snod(c, sleb, buf, offs);
304		if (err)
305			goto error;
306
307		node_len = ALIGN(le32_to_cpu(ch->len), 8);
308		offs += node_len;
309		buf += node_len;
310		len -= node_len;
311	}
312
313	if (offs % c->min_io_size) {
314		if (!quiet)
315			ubifs_err(c, "empty space starts at non-aligned offset %d",
316				  offs);
317		goto corrupted;
318	}
319
320	ubifs_end_scan(c, sleb, lnum, offs);
321
322	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
323		if (*(uint32_t *)buf != 0xffffffff)
324			break;
325	for (; len; offs++, buf++, len--)
326		if (*(uint8_t *)buf != 0xff) {
327			if (!quiet)
328				ubifs_err(c, "corrupt empty space at LEB %d:%d",
329					  lnum, offs);
330			goto corrupted;
331		}
332
333	return sleb;
334
335corrupted:
336	if (!quiet) {
337		ubifs_scanned_corruption(c, lnum, offs, buf);
338		ubifs_err(c, "LEB %d scanning failed", lnum);
339	}
340	err = -EUCLEAN;
341	ubifs_scan_destroy(sleb);
342	return ERR_PTR(err);
343
344error:
345	ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
346	ubifs_scan_destroy(sleb);
347	return ERR_PTR(err);
348}
349
350/**
351 * ubifs_scan_destroy - destroy LEB scanning information.
352 * @sleb: scanning information to free
353 */
354void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
355{
356	struct ubifs_scan_node *node;
357	struct list_head *head;
358
359	head = &sleb->nodes;
360	while (!list_empty(head)) {
361		node = list_entry(head->next, struct ubifs_scan_node, list);
362		list_del(&node->list);
363		kfree(node);
364	}
365	kfree(sleb);
366}
367