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 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 */
28 static 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 */
57 int 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 */
125 struct 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 */
163 void 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 */
181 int 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 */
225 void 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 */
254 struct 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
335 corrupted:
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
344 error:
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 */
354 void 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
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