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