1 /*
2  * This file is part of UBIFS.
3  *
4  * Copyright (C) 2006-2008 Nokia Corporation
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published by
8  * the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
13  * more details.
14  *
15  * You should have received a copy of the GNU General Public License along with
16  * this program; if not, write to the Free Software Foundation, Inc., 51
17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18  *
19  * Authors: Adrian Hunter
20  *          Artem Bityutskiy (Битюцкий Артём)
21  */
22 
23 /*
24  * This file implements the scan which is a general-purpose function for
25  * determining what nodes are in an eraseblock. The scan is used to replay the
26  * journal, to do garbage collection. for the TNC in-the-gaps method, and by
27  * debugging functions.
28  */
29 
30 #include "ubifs.h"
31 
32 /**
33  * scan_padding_bytes - scan for padding bytes.
34  * @buf: buffer to scan
35  * @len: length of buffer
36  *
37  * This function returns the number of padding bytes on success and
38  * %SCANNED_GARBAGE on failure.
39  */
scan_padding_bytes(void * buf,int len)40 static int scan_padding_bytes(void *buf, int len)
41 {
42 	int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
43 	uint8_t *p = buf;
44 
45 	dbg_scan("not a node");
46 
47 	while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
48 		pad_len += 1;
49 
50 	if (!pad_len || (pad_len & 7))
51 		return SCANNED_GARBAGE;
52 
53 	dbg_scan("%d padding bytes", pad_len);
54 
55 	return pad_len;
56 }
57 
58 /**
59  * ubifs_scan_a_node - scan for a node or padding.
60  * @c: UBIFS file-system description object
61  * @buf: buffer to scan
62  * @len: length of buffer
63  * @lnum: logical eraseblock number
64  * @offs: offset within the logical eraseblock
65  * @quiet: print no messages
66  *
67  * This function returns a scanning code to indicate what was scanned.
68  */
ubifs_scan_a_node(const struct ubifs_info * c,void * buf,int len,int lnum,int offs,int quiet)69 int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
70 		      int offs, int quiet)
71 {
72 	struct ubifs_ch *ch = buf;
73 	uint32_t magic;
74 
75 	magic = le32_to_cpu(ch->magic);
76 
77 	if (magic == 0xFFFFFFFF) {
78 		dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
79 		return SCANNED_EMPTY_SPACE;
80 	}
81 
82 	if (magic != UBIFS_NODE_MAGIC)
83 		return scan_padding_bytes(buf, len);
84 
85 	if (len < UBIFS_CH_SZ)
86 		return SCANNED_GARBAGE;
87 
88 	dbg_scan("scanning %s at LEB %d:%d",
89 		 dbg_ntype(ch->node_type), lnum, offs);
90 
91 	if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
92 		return SCANNED_A_CORRUPT_NODE;
93 
94 	if (ch->node_type == UBIFS_PAD_NODE) {
95 		struct ubifs_pad_node *pad = buf;
96 		int pad_len = le32_to_cpu(pad->pad_len);
97 		int node_len = le32_to_cpu(ch->len);
98 
99 		/* Validate the padding node */
100 		if (pad_len < 0 ||
101 		    offs + node_len + pad_len > c->leb_size) {
102 			if (!quiet) {
103 				ubifs_err(c, "bad pad node at LEB %d:%d",
104 					  lnum, offs);
105 				ubifs_dump_node(c, pad);
106 			}
107 			return SCANNED_A_BAD_PAD_NODE;
108 		}
109 
110 		/* Make the node pads to 8-byte boundary */
111 		if ((node_len + pad_len) & 7) {
112 			if (!quiet)
113 				ubifs_err(c, "bad padding length %d - %d",
114 					  offs, offs + node_len + pad_len);
115 			return SCANNED_A_BAD_PAD_NODE;
116 		}
117 
118 		dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
119 			 lnum, offs, ALIGN(offs + node_len + pad_len, 8));
120 
121 		return node_len + pad_len;
122 	}
123 
124 	return SCANNED_A_NODE;
125 }
126 
127 /**
128  * ubifs_start_scan - create LEB scanning information at start of scan.
129  * @c: UBIFS file-system description object
130  * @lnum: logical eraseblock number
131  * @offs: offset to start at (usually zero)
132  * @sbuf: scan buffer (must be c->leb_size)
133  *
134  * This function returns the scanned information on success and a negative error
135  * code on failure.
136  */
ubifs_start_scan(const struct ubifs_info * c,int lnum,int offs,void * sbuf)137 struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
138 					int offs, void *sbuf)
139 {
140 	struct ubifs_scan_leb *sleb;
141 	int err;
142 
143 	dbg_scan("scan LEB %d:%d", lnum, offs);
144 
145 	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
146 	if (!sleb)
147 		return ERR_PTR(-ENOMEM);
148 
149 	sleb->lnum = lnum;
150 	INIT_LIST_HEAD(&sleb->nodes);
151 	sleb->buf = sbuf;
152 
153 	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
154 	if (err && err != -EBADMSG) {
155 		ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
156 			  c->leb_size - offs, lnum, offs, err);
157 		kfree(sleb);
158 		return ERR_PTR(err);
159 	}
160 
161 	/*
162 	 * Note, we ignore integrity errors (EBASMSG) because all the nodes are
163 	 * protected by CRC checksums.
164 	 */
165 	return sleb;
166 }
167 
168 /**
169  * ubifs_end_scan - update LEB scanning information at end of scan.
170  * @c: UBIFS file-system description object
171  * @sleb: scanning information
172  * @lnum: logical eraseblock number
173  * @offs: offset to start at (usually zero)
174  */
ubifs_end_scan(const struct ubifs_info * c,struct ubifs_scan_leb * sleb,int lnum,int offs)175 void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
176 		    int lnum, int offs)
177 {
178 	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
179 	ubifs_assert(c, offs % c->min_io_size == 0);
180 
181 	sleb->endpt = ALIGN(offs, c->min_io_size);
182 }
183 
184 /**
185  * ubifs_add_snod - add a scanned node to LEB scanning information.
186  * @c: UBIFS file-system description object
187  * @sleb: scanning information
188  * @buf: buffer containing node
189  * @offs: offset of node on flash
190  *
191  * This function returns %0 on success and a negative error code on failure.
192  */
ubifs_add_snod(const struct ubifs_info * c,struct ubifs_scan_leb * sleb,void * buf,int offs)193 int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
194 		   void *buf, int offs)
195 {
196 	struct ubifs_ch *ch = buf;
197 	struct ubifs_ino_node *ino = buf;
198 	struct ubifs_scan_node *snod;
199 
200 	snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
201 	if (!snod)
202 		return -ENOMEM;
203 
204 	snod->sqnum = le64_to_cpu(ch->sqnum);
205 	snod->type = ch->node_type;
206 	snod->offs = offs;
207 	snod->len = le32_to_cpu(ch->len);
208 	snod->node = buf;
209 
210 	switch (ch->node_type) {
211 	case UBIFS_INO_NODE:
212 	case UBIFS_DENT_NODE:
213 	case UBIFS_XENT_NODE:
214 	case UBIFS_DATA_NODE:
215 		/*
216 		 * The key is in the same place in all keyed
217 		 * nodes.
218 		 */
219 		key_read(c, &ino->key, &snod->key);
220 		break;
221 	default:
222 		invalid_key_init(c, &snod->key);
223 		break;
224 	}
225 	list_add_tail(&snod->list, &sleb->nodes);
226 	sleb->nodes_cnt += 1;
227 	return 0;
228 }
229 
230 /**
231  * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
232  * @c: UBIFS file-system description object
233  * @lnum: LEB number of corruption
234  * @offs: offset of corruption
235  * @buf: buffer containing corruption
236  */
ubifs_scanned_corruption(const struct ubifs_info * c,int lnum,int offs,void * buf)237 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
238 			      void *buf)
239 {
240 	int len;
241 
242 	ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
243 	len = c->leb_size - offs;
244 	if (len > 8192)
245 		len = 8192;
246 	ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
247 	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
248 }
249 
250 /**
251  * ubifs_scan - scan a logical eraseblock.
252  * @c: UBIFS file-system description object
253  * @lnum: logical eraseblock number
254  * @offs: offset to start at (usually zero)
255  * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
256  * @quiet: print no messages
257  *
258  * This function scans LEB number @lnum and returns complete information about
259  * its contents. Returns the scanned information in case of success and,
260  * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
261  * of failure.
262  *
263  * If @quiet is non-zero, this function does not print large and scary
264  * error messages and flash dumps in case of errors.
265  */
ubifs_scan(const struct ubifs_info * c,int lnum,int offs,void * sbuf,int quiet)266 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
267 				  int offs, void *sbuf, int quiet)
268 {
269 	void *buf = sbuf + offs;
270 	int err, len = c->leb_size - offs;
271 	struct ubifs_scan_leb *sleb;
272 
273 	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
274 	if (IS_ERR(sleb))
275 		return sleb;
276 
277 	while (len >= 8) {
278 		struct ubifs_ch *ch = buf;
279 		int node_len, ret;
280 
281 		dbg_scan("look at LEB %d:%d (%d bytes left)",
282 			 lnum, offs, len);
283 
284 		cond_resched();
285 
286 		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
287 		if (ret > 0) {
288 			/* Padding bytes or a valid padding node */
289 			offs += ret;
290 			buf += ret;
291 			len -= ret;
292 			continue;
293 		}
294 
295 		if (ret == SCANNED_EMPTY_SPACE)
296 			/* Empty space is checked later */
297 			break;
298 
299 		switch (ret) {
300 		case SCANNED_GARBAGE:
301 			ubifs_err(c, "garbage");
302 			goto corrupted;
303 		case SCANNED_A_NODE:
304 			break;
305 		case SCANNED_A_CORRUPT_NODE:
306 		case SCANNED_A_BAD_PAD_NODE:
307 			ubifs_err(c, "bad node");
308 			goto corrupted;
309 		default:
310 			ubifs_err(c, "unknown");
311 			err = -EINVAL;
312 			goto error;
313 		}
314 
315 		err = ubifs_add_snod(c, sleb, buf, offs);
316 		if (err)
317 			goto error;
318 
319 		node_len = ALIGN(le32_to_cpu(ch->len), 8);
320 		offs += node_len;
321 		buf += node_len;
322 		len -= node_len;
323 	}
324 
325 	if (offs % c->min_io_size) {
326 		if (!quiet)
327 			ubifs_err(c, "empty space starts at non-aligned offset %d",
328 				  offs);
329 		goto corrupted;
330 	}
331 
332 	ubifs_end_scan(c, sleb, lnum, offs);
333 
334 	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
335 		if (*(uint32_t *)buf != 0xffffffff)
336 			break;
337 	for (; len; offs++, buf++, len--)
338 		if (*(uint8_t *)buf != 0xff) {
339 			if (!quiet)
340 				ubifs_err(c, "corrupt empty space at LEB %d:%d",
341 					  lnum, offs);
342 			goto corrupted;
343 		}
344 
345 	return sleb;
346 
347 corrupted:
348 	if (!quiet) {
349 		ubifs_scanned_corruption(c, lnum, offs, buf);
350 		ubifs_err(c, "LEB %d scanning failed", lnum);
351 	}
352 	err = -EUCLEAN;
353 	ubifs_scan_destroy(sleb);
354 	return ERR_PTR(err);
355 
356 error:
357 	ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
358 	ubifs_scan_destroy(sleb);
359 	return ERR_PTR(err);
360 }
361 
362 /**
363  * ubifs_scan_destroy - destroy LEB scanning information.
364  * @sleb: scanning information to free
365  */
ubifs_scan_destroy(struct ubifs_scan_leb * sleb)366 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
367 {
368 	struct ubifs_scan_node *node;
369 	struct list_head *head;
370 
371 	head = &sleb->nodes;
372 	while (!list_empty(head)) {
373 		node = list_entry(head->next, struct ubifs_scan_node, list);
374 		list_del(&node->list);
375 		kfree(node);
376 	}
377 	kfree(sleb);
378 }
379