root/fs/ubifs/scan.c

DEFINITIONS

1. scan_padding_bytes
2. ubifs_scan_a_node
3. ubifs_start_scan
4. ubifs_end_scan
5. ubifs_add_snod
6. ubifs_scanned_corruption
7. ubifs_scan_destroy

   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, 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);
  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 }