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1 // SPDX-License-Identifier: GPL-2.0+
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 #ifdef __UBOOT__
19 #include <hexdump.h>
20 #include <linux/err.h>
21 #endif
22 #include "ubifs.h"
23 
24 /**
25  * scan_padding_bytes - scan for padding bytes.
26  * @buf: buffer to scan
27  * @len: length of buffer
28  *
29  * This function returns the number of padding bytes on success and
30  * %SCANNED_GARBAGE on failure.
31  */
scan_padding_bytes(void * buf,int len)32 static int scan_padding_bytes(void *buf, int len)
33 {
34 	int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
35 	uint8_t *p = buf;
36 
37 	dbg_scan("not a node");
38 
39 	while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
40 		pad_len += 1;
41 
42 	if (!pad_len || (pad_len & 7))
43 		return SCANNED_GARBAGE;
44 
45 	dbg_scan("%d padding bytes", pad_len);
46 
47 	return pad_len;
48 }
49 
50 /**
51  * ubifs_scan_a_node - scan for a node or padding.
52  * @c: UBIFS file-system description object
53  * @buf: buffer to scan
54  * @len: length of buffer
55  * @lnum: logical eraseblock number
56  * @offs: offset within the logical eraseblock
57  * @quiet: print no messages
58  *
59  * This function returns a scanning code to indicate what was scanned.
60  */
ubifs_scan_a_node(const struct ubifs_info * c,void * buf,int len,int lnum,int offs,int quiet)61 int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
62 		      int offs, int quiet)
63 {
64 	struct ubifs_ch *ch = buf;
65 	uint32_t magic;
66 
67 	magic = le32_to_cpu(ch->magic);
68 
69 	if (magic == 0xFFFFFFFF) {
70 		dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
71 		return SCANNED_EMPTY_SPACE;
72 	}
73 
74 	if (magic != UBIFS_NODE_MAGIC)
75 		return scan_padding_bytes(buf, len);
76 
77 	if (len < UBIFS_CH_SZ)
78 		return SCANNED_GARBAGE;
79 
80 	dbg_scan("scanning %s at LEB %d:%d",
81 		 dbg_ntype(ch->node_type), lnum, offs);
82 
83 	if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
84 		return SCANNED_A_CORRUPT_NODE;
85 
86 	if (ch->node_type == UBIFS_PAD_NODE) {
87 		struct ubifs_pad_node *pad = buf;
88 		int pad_len = le32_to_cpu(pad->pad_len);
89 		int node_len = le32_to_cpu(ch->len);
90 
91 		/* Validate the padding node */
92 		if (pad_len < 0 ||
93 		    offs + node_len + pad_len > c->leb_size) {
94 			if (!quiet) {
95 				ubifs_err(c, "bad pad node at LEB %d:%d",
96 					  lnum, offs);
97 				ubifs_dump_node(c, pad);
98 			}
99 			return SCANNED_A_BAD_PAD_NODE;
100 		}
101 
102 		/* Make the node pads to 8-byte boundary */
103 		if ((node_len + pad_len) & 7) {
104 			if (!quiet)
105 				ubifs_err(c, "bad padding length %d - %d",
106 					  offs, offs + node_len + pad_len);
107 			return SCANNED_A_BAD_PAD_NODE;
108 		}
109 
110 		dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
111 			 lnum, offs, ALIGN(offs + node_len + pad_len, 8));
112 
113 		return node_len + pad_len;
114 	}
115 
116 	return SCANNED_A_NODE;
117 }
118 
119 /**
120  * ubifs_start_scan - create LEB scanning information at start of scan.
121  * @c: UBIFS file-system description object
122  * @lnum: logical eraseblock number
123  * @offs: offset to start at (usually zero)
124  * @sbuf: scan buffer (must be c->leb_size)
125  *
126  * This function returns the scanned information on success and a negative error
127  * code on failure.
128  */
ubifs_start_scan(const struct ubifs_info * c,int lnum,int offs,void * sbuf)129 struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
130 					int offs, void *sbuf)
131 {
132 	struct ubifs_scan_leb *sleb;
133 	int err;
134 
135 	dbg_scan("scan LEB %d:%d", lnum, offs);
136 
137 	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
138 	if (!sleb)
139 		return ERR_PTR(-ENOMEM);
140 
141 	sleb->lnum = lnum;
142 	INIT_LIST_HEAD(&sleb->nodes);
143 	sleb->buf = sbuf;
144 
145 	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
146 	if (err && err != -EBADMSG) {
147 		ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
148 			  c->leb_size - offs, lnum, offs, err);
149 		kfree(sleb);
150 		return ERR_PTR(err);
151 	}
152 
153 	/*
154 	 * Note, we ignore integrity errors (EBASMSG) because all the nodes are
155 	 * protected by CRC checksums.
156 	 */
157 	return sleb;
158 }
159 
160 /**
161  * ubifs_end_scan - update LEB scanning information at end of scan.
162  * @c: UBIFS file-system description object
163  * @sleb: scanning information
164  * @lnum: logical eraseblock number
165  * @offs: offset to start at (usually zero)
166  */
ubifs_end_scan(const struct ubifs_info * c,struct ubifs_scan_leb * sleb,int lnum,int offs)167 void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
168 		    int lnum, int offs)
169 {
170 	lnum = lnum;
171 	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
172 	ubifs_assert(offs % c->min_io_size == 0);
173 
174 	sleb->endpt = ALIGN(offs, c->min_io_size);
175 }
176 
177 /**
178  * ubifs_add_snod - add a scanned node to LEB scanning information.
179  * @c: UBIFS file-system description object
180  * @sleb: scanning information
181  * @buf: buffer containing node
182  * @offs: offset of node on flash
183  *
184  * This function returns %0 on success and a negative error code on failure.
185  */
ubifs_add_snod(const struct ubifs_info * c,struct ubifs_scan_leb * sleb,void * buf,int offs)186 int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
187 		   void *buf, int offs)
188 {
189 	struct ubifs_ch *ch = buf;
190 	struct ubifs_ino_node *ino = buf;
191 	struct ubifs_scan_node *snod;
192 
193 	snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
194 	if (!snod)
195 		return -ENOMEM;
196 
197 	snod->sqnum = le64_to_cpu(ch->sqnum);
198 	snod->type = ch->node_type;
199 	snod->offs = offs;
200 	snod->len = le32_to_cpu(ch->len);
201 	snod->node = buf;
202 
203 	switch (ch->node_type) {
204 	case UBIFS_INO_NODE:
205 	case UBIFS_DENT_NODE:
206 	case UBIFS_XENT_NODE:
207 	case UBIFS_DATA_NODE:
208 		/*
209 		 * The key is in the same place in all keyed
210 		 * nodes.
211 		 */
212 		key_read(c, &ino->key, &snod->key);
213 		break;
214 	default:
215 		invalid_key_init(c, &snod->key);
216 		break;
217 	}
218 	list_add_tail(&snod->list, &sleb->nodes);
219 	sleb->nodes_cnt += 1;
220 	return 0;
221 }
222 
223 /**
224  * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
225  * @c: UBIFS file-system description object
226  * @lnum: LEB number of corruption
227  * @offs: offset of corruption
228  * @buf: buffer containing corruption
229  */
ubifs_scanned_corruption(const struct ubifs_info * c,int lnum,int offs,void * buf)230 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
231 			      void *buf)
232 {
233 	int len;
234 
235 	ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
236 	len = c->leb_size - offs;
237 	if (len > 8192)
238 		len = 8192;
239 	ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
240 	print_hex_dump("", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
241 }
242 
243 /**
244  * ubifs_scan - scan a logical eraseblock.
245  * @c: UBIFS file-system description object
246  * @lnum: logical eraseblock number
247  * @offs: offset to start at (usually zero)
248  * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
249  * @quiet: print no messages
250  *
251  * This function scans LEB number @lnum and returns complete information about
252  * its contents. Returns the scanned information in case of success and,
253  * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
254  * of failure.
255  *
256  * If @quiet is non-zero, this function does not print large and scary
257  * error messages and flash dumps in case of errors.
258  */
ubifs_scan(const struct ubifs_info * c,int lnum,int offs,void * sbuf,int quiet)259 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
260 				  int offs, void *sbuf, int quiet)
261 {
262 	void *buf = sbuf + offs;
263 	int err, len = c->leb_size - offs;
264 	struct ubifs_scan_leb *sleb;
265 
266 	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
267 	if (IS_ERR(sleb))
268 		return sleb;
269 
270 	while (len >= 8) {
271 		struct ubifs_ch *ch = buf;
272 		int node_len, ret;
273 
274 		dbg_scan("look at LEB %d:%d (%d bytes left)",
275 			 lnum, offs, len);
276 
277 		cond_resched();
278 
279 		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
280 		if (ret > 0) {
281 			/* Padding bytes or a valid padding node */
282 			offs += ret;
283 			buf += ret;
284 			len -= ret;
285 			continue;
286 		}
287 
288 		if (ret == SCANNED_EMPTY_SPACE)
289 			/* Empty space is checked later */
290 			break;
291 
292 		switch (ret) {
293 		case SCANNED_GARBAGE:
294 			ubifs_err(c, "garbage");
295 			goto corrupted;
296 		case SCANNED_A_NODE:
297 			break;
298 		case SCANNED_A_CORRUPT_NODE:
299 		case SCANNED_A_BAD_PAD_NODE:
300 			ubifs_err(c, "bad node");
301 			goto corrupted;
302 		default:
303 			ubifs_err(c, "unknown");
304 			err = -EINVAL;
305 			goto error;
306 		}
307 
308 		err = ubifs_add_snod(c, sleb, buf, offs);
309 		if (err)
310 			goto error;
311 
312 		node_len = ALIGN(le32_to_cpu(ch->len), 8);
313 		offs += node_len;
314 		buf += node_len;
315 		len -= node_len;
316 	}
317 
318 	if (offs % c->min_io_size) {
319 		if (!quiet)
320 			ubifs_err(c, "empty space starts at non-aligned offset %d",
321 				  offs);
322 		goto corrupted;
323 	}
324 
325 	ubifs_end_scan(c, sleb, lnum, offs);
326 
327 	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
328 		if (*(uint32_t *)buf != 0xffffffff)
329 			break;
330 	for (; len; offs++, buf++, len--)
331 		if (*(uint8_t *)buf != 0xff) {
332 			if (!quiet)
333 				ubifs_err(c, "corrupt empty space at LEB %d:%d",
334 					  lnum, offs);
335 			goto corrupted;
336 		}
337 
338 	return sleb;
339 
340 corrupted:
341 	if (!quiet) {
342 		ubifs_scanned_corruption(c, lnum, offs, buf);
343 		ubifs_err(c, "LEB %d scanning failed", lnum);
344 	}
345 	err = -EUCLEAN;
346 	ubifs_scan_destroy(sleb);
347 	return ERR_PTR(err);
348 
349 error:
350 	ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
351 	ubifs_scan_destroy(sleb);
352 	return ERR_PTR(err);
353 }
354 
355 /**
356  * ubifs_scan_destroy - destroy LEB scanning information.
357  * @sleb: scanning information to free
358  */
ubifs_scan_destroy(struct ubifs_scan_leb * sleb)359 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
360 {
361 	struct ubifs_scan_node *node;
362 	struct list_head *head;
363 
364 	head = &sleb->nodes;
365 	while (!list_empty(head)) {
366 		node = list_entry(head->next, struct ubifs_scan_node, list);
367 		list_del(&node->list);
368 		kfree(node);
369 	}
370 	kfree(sleb);
371 }
372