lib/ext2fs/csum.c

   1 /*
   2  * csum.c --- checksumming of ext3 structures
   3  *
   4  * Copyright (C) 2006 Cluster File Systems, Inc.
   5  * Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com>
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Library
   9  * General Public License, version 2.
  10  * %End-Header%
  11  */
  12
  13 #include "config.h"
  14 #if HAVE_SYS_TYPES_H
  15 #include <sys/types.h>
  16 #endif
  17
  18 #include "ext2_fs.h"
  19 #include "ext2fs.h"
  20 #include "crc16.h"
  21 #include <assert.h>
  22
  23 #ifndef offsetof
  24 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
  25 #endif
  26
  27 #ifdef DEBUG
  28 #define STATIC
  29 #else
  30 #define STATIC static
  31 #endif
  32
  33 static __u32 ext2fs_mmp_csum(ext2_filsys fs, struct mmp_struct *mmp)
  34 {
  35         int offset = offsetof(struct mmp_struct, mmp_checksum);
  36
  37         return ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)mmp, offset);
  38 }
  39
  40 int ext2fs_mmp_csum_verify(ext2_filsys fs, struct mmp_struct *mmp)
  41 {
  42         __u32 calculated;
  43
  44         if (!ext2fs_has_feature_metadata_csum(fs->super))
  45                 return 1;
  46
  47         calculated = ext2fs_mmp_csum(fs, mmp);
  48
  49         return ext2fs_le32_to_cpu(mmp->mmp_checksum) == calculated;
  50 }
  51
  52 errcode_t ext2fs_mmp_csum_set(ext2_filsys fs, struct mmp_struct *mmp)
  53 {
  54         __u32 crc;
  55
  56         if (!ext2fs_has_feature_metadata_csum(fs->super))
  57                 return 0;
  58
  59         crc = ext2fs_mmp_csum(fs, mmp);
  60         mmp->mmp_checksum = ext2fs_cpu_to_le32(crc);
  61
  62         return 0;
  63 }
  64
  65 int ext2fs_verify_csum_type(ext2_filsys fs, struct ext2_super_block *sb)
  66 {
  67         if (!ext2fs_has_feature_metadata_csum(fs->super))
  68                 return 1;
  69
  70         return sb->s_checksum_type == EXT2_CRC32C_CHKSUM;
  71 }
  72
  73 static __u32 ext2fs_superblock_csum(ext2_filsys fs EXT2FS_ATTR((unused)),
  74                                     struct ext2_super_block *sb)
  75 {
  76         int offset = offsetof(struct ext2_super_block, s_checksum);
  77
  78         return ext2fs_crc32c_le(~0, (unsigned char *)sb, offset);
  79 }
  80
  81 /* NOTE: The input to this function MUST be in LE order */
  82 int ext2fs_superblock_csum_verify(ext2_filsys fs, struct ext2_super_block *sb)
  83 {
  84         __u32 flag, calculated;
  85
  86         if (fs->flags & EXT2_FLAG_SWAP_BYTES)
  87                 flag = EXT4_FEATURE_RO_COMPAT_METADATA_CSUM;
  88         else
  89                 flag = ext2fs_cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
  90
  91         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, flag))
  92                 return 1;
  93
  94         calculated = ext2fs_superblock_csum(fs, sb);
  95
  96         return ext2fs_le32_to_cpu(sb->s_checksum) == calculated;
  97 }
  98
  99 /* NOTE: The input to this function MUST be in LE order */
 100 errcode_t ext2fs_superblock_csum_set(ext2_filsys fs,
 101                                      struct ext2_super_block *sb)
 102 {
 103         __u32 flag, crc;
 104
 105         if (fs->flags & EXT2_FLAG_SWAP_BYTES)
 106                 flag = EXT4_FEATURE_RO_COMPAT_METADATA_CSUM;
 107         else
 108                 flag = ext2fs_cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
 109
 110         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, flag))
 111                 return 0;
 112
 113         crc = ext2fs_superblock_csum(fs, sb);
 114         sb->s_checksum = ext2fs_cpu_to_le32(crc);
 115
 116         return 0;
 117 }
 118
 119 static errcode_t ext2fs_ext_attr_block_csum(ext2_filsys fs,
 120                                             ext2_ino_t inum EXT2FS_ATTR((unused)),
 121                                             blk64_t block,
 122                                             struct ext2_ext_attr_header *hdr,
 123                                             __u32 *crc)
 124 {
 125         char *buf = (char *)hdr;
 126         __u32 old_crc = hdr->h_checksum;
 127
 128         hdr->h_checksum = 0;
 129         block = ext2fs_cpu_to_le64(block);
 130         *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&block,
 131                                 sizeof(block));
 132         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, fs->blocksize);
 133         hdr->h_checksum = old_crc;
 134
 135         return 0;
 136 }
 137
 138 int ext2fs_ext_attr_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 139                                       blk64_t block,
 140                                       struct ext2_ext_attr_header *hdr)
 141 {
 142         __u32 calculated;
 143         errcode_t retval;
 144
 145         if (!ext2fs_has_feature_metadata_csum(fs->super))
 146                 return 1;
 147
 148         retval = ext2fs_ext_attr_block_csum(fs, inum, block, hdr, &calculated);
 149         if (retval)
 150                 return 0;
 151
 152         return ext2fs_le32_to_cpu(hdr->h_checksum) == calculated;
 153 }
 154
 155 errcode_t ext2fs_ext_attr_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
 156                                          blk64_t block,
 157                                          struct ext2_ext_attr_header *hdr)
 158 {
 159         errcode_t retval;
 160         __u32 crc;
 161
 162         if (!ext2fs_has_feature_metadata_csum(fs->super))
 163                 return 0;
 164
 165         retval = ext2fs_ext_attr_block_csum(fs, inum, block, hdr, &crc);
 166         if (retval)
 167                 return retval;
 168         hdr->h_checksum = ext2fs_cpu_to_le32(crc);
 169         return 0;
 170 }
 171
 172 static __u16 do_nothing16(__u16 x)
 173 {
 174         return x;
 175 }
 176
 177 static __u16 disk_to_host16(__u16 x)
 178 {
 179         return ext2fs_le16_to_cpu(x);
 180 }
 181
 182 static errcode_t __get_dx_countlimit(ext2_filsys fs,
 183                                      struct ext2_dir_entry *dirent,
 184                                      struct ext2_dx_countlimit **cc,
 185                                      int *offset,
 186                                      int need_swab)
 187 {
 188         struct ext2_dir_entry *dp;
 189         struct ext2_dx_root_info *root;
 190         struct ext2_dx_countlimit *c;
 191         int count_offset, max_sane_entries;
 192         unsigned int rec_len;
 193         __u16 (*translate)(__u16) = (need_swab ? disk_to_host16 : do_nothing16);
 194
 195         rec_len = translate(dirent->rec_len);
 196
 197         if (rec_len == fs->blocksize && translate(dirent->name_len) == 0)
 198                 count_offset = 8;
 199         else if (rec_len == 12) {
 200                 dp = (struct ext2_dir_entry *)(((char *)dirent) + rec_len);
 201                 rec_len = translate(dp->rec_len);
 202                 if (rec_len != fs->blocksize - 12)
 203                         return EXT2_ET_DB_NOT_FOUND;
 204                 root = (struct ext2_dx_root_info *)(((char *)dp + 12));
 205                 if (root->reserved_zero ||
 206                     root->info_length != sizeof(struct ext2_dx_root_info))
 207                         return EXT2_ET_DB_NOT_FOUND;
 208                 count_offset = 32;
 209         } else
 210                 return EXT2_ET_DB_NOT_FOUND;
 211
 212         c = (struct ext2_dx_countlimit *)(((char *)dirent) + count_offset);
 213         max_sane_entries = (fs->blocksize - count_offset) /
 214                            sizeof(struct ext2_dx_entry);
 215         if (ext2fs_le16_to_cpu(c->limit) > max_sane_entries ||
 216             ext2fs_le16_to_cpu(c->count) > max_sane_entries)
 217                 return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
 218
 219         if (offset)
 220                 *offset = count_offset;
 221         if (cc)
 222                 *cc = c;
 223
 224         return 0;
 225 }
 226
 227 errcode_t ext2fs_get_dx_countlimit(ext2_filsys fs,
 228                                    struct ext2_dir_entry *dirent,
 229                                    struct ext2_dx_countlimit **cc,
 230                                    int *offset)
 231 {
 232         return __get_dx_countlimit(fs, dirent, cc, offset, 0);
 233 }
 234
 235 void ext2fs_initialize_dirent_tail(ext2_filsys fs,
 236                                    struct ext2_dir_entry_tail *t)
 237 {
 238         memset(t, 0, sizeof(struct ext2_dir_entry_tail));
 239         ext2fs_set_rec_len(fs, sizeof(struct ext2_dir_entry_tail),
 240                            (struct ext2_dir_entry *)t);
 241         t->det_reserved_name_len = EXT2_DIR_NAME_LEN_CSUM;
 242 }
 243
 244 static errcode_t __get_dirent_tail(ext2_filsys fs,
 245                                    struct ext2_dir_entry *dirent,
 246                                    struct ext2_dir_entry_tail **tt,
 247                                    int need_swab)
 248 {
 249         struct ext2_dir_entry *d;
 250         void *top;
 251         struct ext2_dir_entry_tail *t;
 252         unsigned int rec_len;
 253         errcode_t retval = 0;
 254         __u16 (*translate)(__u16) = (need_swab ? disk_to_host16 : do_nothing16);
 255
 256         d = dirent;
 257         top = EXT2_DIRENT_TAIL(dirent, fs->blocksize);
 258
 259         rec_len = translate(d->rec_len);
 260         while (rec_len && !(rec_len & 0x3)) {
 261                 d = (struct ext2_dir_entry *)(((char *)d) + rec_len);
 262                 if ((void *)d >= top)
 263                         break;
 264                 rec_len = translate(d->rec_len);
 265         }
 266
 267         if (d != top)
 268                 return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
 269
 270         t = (struct ext2_dir_entry_tail *)d;
 271         if (t->det_reserved_zero1 ||
 272             translate(t->det_rec_len) != sizeof(struct ext2_dir_entry_tail) ||
 273             translate(t->det_reserved_name_len) != EXT2_DIR_NAME_LEN_CSUM)
 274                 return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
 275
 276         if (tt)
 277                 *tt = t;
 278         return retval;
 279 }
 280
 281 int ext2fs_dirent_has_tail(ext2_filsys fs, struct ext2_dir_entry *dirent)
 282 {
 283         return __get_dirent_tail(fs, dirent, NULL, 0) == 0;
 284 }
 285
 286 static errcode_t ext2fs_dirent_csum(ext2_filsys fs, ext2_ino_t inum,
 287                                     struct ext2_dir_entry *dirent, __u32 *crc,
 288                                     int size)
 289 {
 290         errcode_t retval;
 291         char *buf = (char *)dirent;
 292         __u32 gen;
 293         struct ext2_inode inode;
 294
 295         retval = ext2fs_read_inode(fs, inum, &inode);
 296         if (retval)
 297                 return retval;
 298
 299         inum = ext2fs_cpu_to_le32(inum);
 300         gen = ext2fs_cpu_to_le32(inode.i_generation);
 301         *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
 302                                 sizeof(inum));
 303         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
 304         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, size);
 305
 306         return 0;
 307 }
 308
 309 int ext2fs_dirent_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 310                               struct ext2_dir_entry *dirent)
 311 {
 312         errcode_t retval;
 313         __u32 calculated;
 314         struct ext2_dir_entry_tail *t;
 315
 316         retval = __get_dirent_tail(fs, dirent, &t, 1);
 317         if (retval)
 318                 return 1;
 319
 320         /*
 321          * The checksum field is overlaid with the dirent->name field
 322          * so the swapfs.c functions won't change the endianness.
 323          */
 324         retval = ext2fs_dirent_csum(fs, inum, dirent, &calculated,
 325                                     (char *)t - (char *)dirent);
 326         if (retval)
 327                 return 0;
 328         return ext2fs_le32_to_cpu(t->det_checksum) == calculated;
 329 }
 330
 331 static errcode_t ext2fs_dirent_csum_set(ext2_filsys fs, ext2_ino_t inum,
 332                                         struct ext2_dir_entry *dirent)
 333 {
 334         errcode_t retval;
 335         __u32 crc;
 336         struct ext2_dir_entry_tail *t;
 337
 338         retval = __get_dirent_tail(fs, dirent, &t, 1);
 339         if (retval)
 340                 return retval;
 341
 342         /* swapfs.c functions don't change the checksum endianness */
 343         retval = ext2fs_dirent_csum(fs, inum, dirent, &crc,
 344                                     (char *)t - (char *)dirent);
 345         if (retval)
 346                 return retval;
 347         t->det_checksum = ext2fs_cpu_to_le32(crc);
 348         return 0;
 349 }
 350
 351 static errcode_t ext2fs_dx_csum(ext2_filsys fs, ext2_ino_t inum,
 352                                 struct ext2_dir_entry *dirent,
 353                                 __u32 *crc, int count_offset, int count,
 354                                 struct ext2_dx_tail *t)
 355 {
 356         errcode_t retval;
 357         char *buf = (char *)dirent;
 358         int size;
 359         __u32 old_csum, gen;
 360         struct ext2_inode inode;
 361
 362         size = count_offset + (count * sizeof(struct ext2_dx_entry));
 363         old_csum = t->dt_checksum;
 364         t->dt_checksum = 0;
 365
 366         retval = ext2fs_read_inode(fs, inum, &inode);
 367         if (retval)
 368                 return retval;
 369
 370         inum = ext2fs_cpu_to_le32(inum);
 371         gen = ext2fs_cpu_to_le32(inode.i_generation);
 372         *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
 373                                 sizeof(inum));
 374         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
 375         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, size);
 376         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)t,
 377                                 sizeof(struct ext2_dx_tail));
 378         t->dt_checksum = old_csum;
 379
 380         return 0;
 381 }
 382
 383 static int ext2fs_dx_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 384                                  struct ext2_dir_entry *dirent)
 385 {
 386         __u32 calculated;
 387         errcode_t retval;
 388         struct ext2_dx_countlimit *c;
 389         struct ext2_dx_tail *t;
 390         int count_offset, limit, count;
 391
 392         retval = __get_dx_countlimit(fs, dirent, &c, &count_offset, 1);
 393         if (retval)
 394                 return 1;
 395         limit = ext2fs_le16_to_cpu(c->limit);
 396         count = ext2fs_le16_to_cpu(c->count);
 397         if (count_offset + (limit * sizeof(struct ext2_dx_entry)) >
 398             fs->blocksize - sizeof(struct ext2_dx_tail))
 399                 return 0;
 400         /* htree structs are accessed in LE order */
 401         t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);
 402         retval = ext2fs_dx_csum(fs, inum, dirent, &calculated, count_offset,
 403                                 count, t);
 404         if (retval)
 405                 return 0;
 406
 407         return ext2fs_le32_to_cpu(t->dt_checksum) == calculated;
 408 }
 409
 410 static errcode_t ext2fs_dx_csum_set(ext2_filsys fs, ext2_ino_t inum,
 411                                     struct ext2_dir_entry *dirent)
 412 {
 413         __u32 crc;
 414         errcode_t retval = 0;
 415         struct ext2_dx_countlimit *c;
 416         struct ext2_dx_tail *t;
 417         int count_offset, limit, count;
 418
 419         retval = __get_dx_countlimit(fs, dirent, &c, &count_offset, 1);
 420         if (retval)
 421                 return retval;
 422         limit = ext2fs_le16_to_cpu(c->limit);
 423         count = ext2fs_le16_to_cpu(c->count);
 424         if (count_offset + (limit * sizeof(struct ext2_dx_entry)) >
 425             fs->blocksize - sizeof(struct ext2_dx_tail))
 426                 return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
 427         t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);
 428
 429         /* htree structs are accessed in LE order */
 430         retval = ext2fs_dx_csum(fs, inum, dirent, &crc, count_offset, count, t);
 431         if (retval)
 432                 return retval;
 433         t->dt_checksum = ext2fs_cpu_to_le32(crc);
 434         return retval;
 435 }
 436
 437 int ext2fs_dir_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 438                                  struct ext2_dir_entry *dirent)
 439 {
 440         if (!ext2fs_has_feature_metadata_csum(fs->super))
 441                 return 1;
 442
 443         if (__get_dirent_tail(fs, dirent, NULL, 1) == 0)
 444                 return ext2fs_dirent_csum_verify(fs, inum, dirent);
 445         if (__get_dx_countlimit(fs, dirent, NULL, NULL, 1) == 0)
 446                 return ext2fs_dx_csum_verify(fs, inum, dirent);
 447
 448         return 0;
 449 }
 450
 451 errcode_t ext2fs_dir_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
 452                                     struct ext2_dir_entry *dirent)
 453 {
 454         if (!ext2fs_has_feature_metadata_csum(fs->super))
 455                 return 0;
 456
 457         if (__get_dirent_tail(fs, dirent, NULL, 1) == 0)
 458                 return ext2fs_dirent_csum_set(fs, inum, dirent);
 459         if (__get_dx_countlimit(fs, dirent, NULL, NULL, 1) == 0)
 460                 return ext2fs_dx_csum_set(fs, inum, dirent);
 461
 462         if (fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)
 463                 return 0;
 464         return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
 465 }
 466
 467 #define EXT3_EXTENT_TAIL_OFFSET(hdr)    (sizeof(struct ext3_extent_header) + \
 468         (sizeof(struct ext3_extent) * ext2fs_le16_to_cpu((hdr)->eh_max)))
 469
 470 static struct ext3_extent_tail *get_extent_tail(struct ext3_extent_header *h)
 471 {
 472         return (struct ext3_extent_tail *)(((char *)h) +
 473                                            EXT3_EXTENT_TAIL_OFFSET(h));
 474 }
 475
 476 static errcode_t ext2fs_extent_block_csum(ext2_filsys fs, ext2_ino_t inum,
 477                                           struct ext3_extent_header *eh,
 478                                           __u32 *crc)
 479 {
 480         int size;
 481         __u32 gen;
 482         errcode_t retval;
 483         struct ext2_inode inode;
 484
 485         size = EXT3_EXTENT_TAIL_OFFSET(eh) + offsetof(struct ext3_extent_tail,
 486                                                       et_checksum);
 487
 488         retval = ext2fs_read_inode(fs, inum, &inode);
 489         if (retval)
 490                 return retval;
 491         inum = ext2fs_cpu_to_le32(inum);
 492         gen = ext2fs_cpu_to_le32(inode.i_generation);
 493         *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
 494                                 sizeof(inum));
 495         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
 496         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)eh, size);
 497
 498         return 0;
 499 }
 500
 501 int ext2fs_extent_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 502                                     struct ext3_extent_header *eh)
 503 {
 504         errcode_t retval;
 505         __u32 provided, calculated;
 506         struct ext3_extent_tail *t = get_extent_tail(eh);
 507
 508         /*
 509          * The extent tree structures are accessed in LE order, so we must
 510          * swap the checksum bytes here.
 511          */
 512         if (!ext2fs_has_feature_metadata_csum(fs->super))
 513                 return 1;
 514
 515         provided = ext2fs_le32_to_cpu(t->et_checksum);
 516         retval = ext2fs_extent_block_csum(fs, inum, eh, &calculated);
 517         if (retval)
 518                 return 0;
 519
 520         return provided == calculated;
 521 }
 522
 523 errcode_t ext2fs_extent_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
 524                                        struct ext3_extent_header *eh)
 525 {
 526         errcode_t retval;
 527         __u32 crc;
 528         struct ext3_extent_tail *t = get_extent_tail(eh);
 529
 530         if (!ext2fs_has_feature_metadata_csum(fs->super))
 531                 return 0;
 532
 533         /*
 534          * The extent tree structures are accessed in LE order, so we must
 535          * swap the checksum bytes here.
 536          */
 537         retval = ext2fs_extent_block_csum(fs, inum, eh, &crc);
 538         if (retval)
 539                 return retval;
 540         t->et_checksum = ext2fs_cpu_to_le32(crc);
 541         return retval;
 542 }
 543
 544 int ext2fs_inode_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
 545                                     char *bitmap, int size)
 546 {
 547         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
 548                         ext2fs_group_desc(fs, fs->group_desc, group);
 549         __u32 provided, calculated;
 550
 551         if (!ext2fs_has_feature_metadata_csum(fs->super))
 552                 return 1;
 553         provided = gdp->bg_inode_bitmap_csum_lo;
 554         calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
 555                                       size);
 556         if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
 557                 provided |= (__u32)gdp->bg_inode_bitmap_csum_hi << 16;
 558         else
 559                 calculated &= 0xFFFF;
 560
 561         return provided == calculated;
 562 }
 563
 564 errcode_t ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
 565                                        char *bitmap, int size)
 566 {
 567         __u32 crc;
 568         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
 569                         ext2fs_group_desc(fs, fs->group_desc, group);
 570
 571         if (!ext2fs_has_feature_metadata_csum(fs->super))
 572                 return 0;
 573
 574         crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
 575         gdp->bg_inode_bitmap_csum_lo = crc & 0xFFFF;
 576         if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
 577                 gdp->bg_inode_bitmap_csum_hi = crc >> 16;
 578
 579         return 0;
 580 }
 581
 582 int ext2fs_block_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
 583                                     char *bitmap, int size)
 584 {
 585         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
 586                         ext2fs_group_desc(fs, fs->group_desc, group);
 587         __u32 provided, calculated;
 588
 589         if (!ext2fs_has_feature_metadata_csum(fs->super))
 590                 return 1;
 591         provided = gdp->bg_block_bitmap_csum_lo;
 592         calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
 593                                       size);
 594         if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
 595                 provided |= (__u32)gdp->bg_block_bitmap_csum_hi << 16;
 596         else
 597                 calculated &= 0xFFFF;
 598
 599         return provided == calculated;
 600 }
 601
 602 errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
 603                                        char *bitmap, int size)
 604 {
 605         __u32 crc;
 606         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
 607                         ext2fs_group_desc(fs, fs->group_desc, group);
 608
 609         if (!ext2fs_has_feature_metadata_csum(fs->super))
 610                 return 0;
 611
 612         crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
 613         gdp->bg_block_bitmap_csum_lo = crc & 0xFFFF;
 614         if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
 615                 gdp->bg_block_bitmap_csum_hi = crc >> 16;
 616
 617         return 0;
 618 }
 619
 620 static errcode_t ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
 621                                struct ext2_inode_large *inode,
 622                                __u32 *crc, int has_hi)
 623 {
 624         __u32 gen;
 625         struct ext2_inode_large *desc = inode;
 626         size_t size = fs->super->s_inode_size;
 627         __u16 old_lo;
 628         __u16 old_hi = 0;
 629
 630         old_lo = inode->i_checksum_lo;
 631         inode->i_checksum_lo = 0;
 632         if (has_hi) {
 633                 old_hi = inode->i_checksum_hi;
 634                 inode->i_checksum_hi = 0;
 635         }
 636
 637         inum = ext2fs_cpu_to_le32(inum);
 638         gen = inode->i_generation;
 639         *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
 640                                 sizeof(inum));
 641         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
 642         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)desc, size);
 643
 644         inode->i_checksum_lo = old_lo;
 645         if (has_hi)
 646                 inode->i_checksum_hi = old_hi;
 647         return 0;
 648 }
 649
 650 int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 651                              struct ext2_inode_large *inode)
 652 {
 653         errcode_t retval;
 654         __u32 provided, calculated;
 655         unsigned int i, has_hi;
 656         char *cp;
 657
 658         if (fs->super->s_creator_os != EXT2_OS_LINUX ||
 659             !ext2fs_has_feature_metadata_csum(fs->super))
 660                 return 1;
 661
 662         has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
 663                   inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
 664
 665         provided = ext2fs_le16_to_cpu(inode->i_checksum_lo);
 666         retval = ext2fs_inode_csum(fs, inum, inode, &calculated, has_hi);
 667         if (retval)
 668                 return 0;
 669         if (has_hi) {
 670                 __u32 hi = ext2fs_le16_to_cpu(inode->i_checksum_hi);
 671                 provided |= hi << 16;
 672         } else
 673                 calculated &= 0xFFFF;
 674
 675         if (provided == calculated)
 676                 return 1;
 677
 678         /*
 679          * If the checksum didn't match, it's possible it was due to
 680          * the inode being all zero's.  It's unlikely this is the
 681          * case, but it can happen.  So check for it here.  (We only
 682          * check the base inode since that's good enough, and it's not
 683          * worth the bother to figure out how much of the extended
 684          * inode, if any, is present.)
 685          */
 686         for (cp = (char *) inode, i = 0;
 687              i < sizeof(struct ext2_inode);
 688              cp++, i++)
 689                 if (*cp)
 690                         return 0;
 691         return 1;               /* Inode must have been all zero's */
 692 }
 693
 694 errcode_t ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
 695                            struct ext2_inode_large *inode)
 696 {
 697         errcode_t retval;
 698         __u32 crc;
 699         int has_hi;
 700
 701         if (fs->super->s_creator_os != EXT2_OS_LINUX ||
 702             !ext2fs_has_feature_metadata_csum(fs->super))
 703                 return 0;
 704
 705         has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
 706                   inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
 707
 708         retval = ext2fs_inode_csum(fs, inum, inode, &crc, has_hi);
 709         if (retval)
 710                 return retval;
 711         inode->i_checksum_lo = ext2fs_cpu_to_le16(crc & 0xFFFF);
 712         if (has_hi)
 713                 inode->i_checksum_hi = ext2fs_cpu_to_le16(crc >> 16);
 714         return 0;
 715 }
 716
 717 __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 718 {
 719         struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
 720                                                          group);
 721         size_t offset, size = EXT2_DESC_SIZE(fs->super);
 722         __u16 crc = 0;
 723 #ifdef WORDS_BIGENDIAN
 724         struct ext4_group_desc swabdesc;
 725         size_t save_size = size;
 726         const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
 727         struct ext2_group_desc *save_desc = desc;
 728
 729         /* Have to swab back to little-endian to do the checksum */
 730         if (size > ext4_bg_size)
 731                 size = ext4_bg_size;
 732         memcpy(&swabdesc, desc, size);
 733         ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
 734         desc = (struct ext2_group_desc *) &swabdesc;
 735         group = ext2fs_swab32(group);
 736 #endif
 737
 738         if (ext2fs_has_feature_metadata_csum(fs->super)) {
 739                 /* new metadata csum code */
 740                 __u16 old_crc;
 741                 __u32 crc32;
 742
 743                 old_crc = desc->bg_checksum;
 744                 desc->bg_checksum = 0;
 745                 crc32 = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&group,
 746                                          sizeof(group));
 747                 crc32 = ext2fs_crc32c_le(crc32, (unsigned char *)desc,
 748                                          size);
 749                 desc->bg_checksum = old_crc;
 750 #ifdef WORDS_BIGENDIAN
 751                 if (save_size > ext4_bg_size)
 752                         crc32 = ext2fs_crc32c_le(crc32,
 753                                      (unsigned char *)save_desc + ext4_bg_size,
 754                                      save_size - ext4_bg_size);
 755 #endif
 756                 crc = crc32 & 0xFFFF;
 757                 goto out;
 758         }
 759
 760         /* old crc16 code */
 761         offset = offsetof(struct ext2_group_desc, bg_checksum);
 762         crc = ext2fs_crc16(~0, fs->super->s_uuid,
 763                            sizeof(fs->super->s_uuid));
 764         crc = ext2fs_crc16(crc, &group, sizeof(group));
 765         crc = ext2fs_crc16(crc, desc, offset);
 766         offset += sizeof(desc->bg_checksum); /* skip checksum */
 767         /* for checksum of struct ext4_group_desc do the rest...*/
 768         if (offset < size) {
 769                 crc = ext2fs_crc16(crc, (char *)desc + offset,
 770                                    size - offset);
 771         }
 772 #ifdef WORDS_BIGENDIAN
 773         /*
 774          * If the size of the bg descriptor is greater than 64
 775          * bytes, which is the size of the traditional ext4 bg
 776          * descriptor, checksum the rest of the descriptor here
 777          */
 778         if (save_size > ext4_bg_size)
 779                 crc = ext2fs_crc16(crc, (char *)save_desc + ext4_bg_size,
 780                                    save_size - ext4_bg_size);
 781 #endif
 782
 783 out:
 784         return crc;
 785 }
 786
 787 int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
 788 {
 789         if (ext2fs_has_group_desc_csum(fs) &&
 790             (ext2fs_bg_checksum(fs, group) !=
 791              ext2fs_group_desc_csum(fs, group)))
 792                 return 0;
 793
 794         return 1;
 795 }
 796
 797 void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
 798 {
 799         if (!ext2fs_has_group_desc_csum(fs))
 800                 return;
 801
 802         /* ext2fs_bg_checksum_set() sets the actual checksum field but
 803          * does not calculate the checksum itself. */
 804         ext2fs_bg_checksum_set(fs, group, ext2fs_group_desc_csum(fs, group));
 805 }
 806
 807 static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
 808                                    __u32 inodes_per_grp, dgrp_t grp_no)
 809 {
 810         ext2_ino_t i, start_ino, end_ino;
 811
 812         start_ino = grp_no * inodes_per_grp + 1;
 813         end_ino = start_ino + inodes_per_grp - 1;
 814
 815         for (i = end_ino; i >= start_ino; i--) {
 816                 if (ext2fs_fast_test_inode_bitmap2(bitmap, i))
 817                         return i - start_ino + 1;
 818         }
 819         return inodes_per_grp;
 820 }
 821
 822 /* update the bitmap flags, set the itable high watermark, and calculate
 823  * checksums for the group descriptors */
 824 errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
 825 {
 826         struct ext2_super_block *sb = fs->super;
 827         int dirty = 0;
 828         dgrp_t i;
 829
 830         if (!fs->inode_map)
 831                 return EXT2_ET_NO_INODE_BITMAP;
 832
 833         if (!ext2fs_has_group_desc_csum(fs))
 834                 return 0;
 835
 836         for (i = 0; i < fs->group_desc_count; i++) {
 837                 __u32 old_csum = ext2fs_bg_checksum(fs, i);
 838                 __u32 old_unused = ext2fs_bg_itable_unused(fs, i);
 839                 __u32 old_flags = ext2fs_bg_flags(fs, i);
 840                 __u32 old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i);
 841                 __u32 old_free_blocks_count = ext2fs_bg_free_blocks_count(fs, i);
 842
 843                 if (old_free_blocks_count == sb->s_blocks_per_group &&
 844                     i != fs->group_desc_count - 1)
 845                         ext2fs_bg_flags_set(fs, i, EXT2_BG_BLOCK_UNINIT);
 846
 847                 if (old_free_inodes_count == sb->s_inodes_per_group) {
 848                         ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
 849                         ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group);
 850                 } else {
 851                         int unused =
 852                                 sb->s_inodes_per_group -
 853                                 find_last_inode_ingrp(fs->inode_map,
 854                                                       sb->s_inodes_per_group, i);
 855
 856                         ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT);
 857                         ext2fs_bg_itable_unused_set(fs, i, unused);
 858                 }
 859
 860                 ext2fs_group_desc_csum_set(fs, i);
 861                 if (old_flags != ext2fs_bg_flags(fs, i))
 862                         dirty = 1;
 863                 if (old_unused != ext2fs_bg_itable_unused(fs, i))
 864                         dirty = 1;
 865                 if (old_csum != ext2fs_bg_checksum(fs, i))
 866                         dirty = 1;
 867         }
 868         if (dirty)
 869                 ext2fs_mark_super_dirty(fs);
 870         return 0;
 871 }
 872
 873 #ifdef DEBUG
 874 #include "e2p/e2p.h"
 875
 876 void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
 877 {
 878         __u16 crc1, crc2, crc3;
 879         dgrp_t swabgroup;
 880         struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
 881                                                          group);
 882         size_t size = EXT2_DESC_SIZE(fs->super);
 883         struct ext2_super_block *sb = fs->super;
 884         int offset = offsetof(struct ext2_group_desc, bg_checksum);
 885 #ifdef WORDS_BIGENDIAN
 886         struct ext4_group_desc swabdesc;
 887         struct ext2_group_desc *save_desc = desc;
 888         const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
 889         size_t save_size = size;
 890 #endif
 891
 892 #ifdef WORDS_BIGENDIAN
 893         /* Have to swab back to little-endian to do the checksum */
 894         if (size > ext4_bg_size)
 895                 size = ext4_bg_size;
 896         memcpy(&swabdesc, desc, size);
 897         ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
 898         desc = (struct ext2_group_desc *) &swabdesc;
 899
 900         swabgroup = ext2fs_swab32(group);
 901 #else
 902         swabgroup = group;
 903 #endif
 904
 905         crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
 906         crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
 907         crc3 = ext2fs_crc16(crc2, desc, offset);
 908         offset += sizeof(desc->bg_checksum); /* skip checksum */
 909         /* for checksum of struct ext4_group_desc do the rest...*/
 910         if (offset < size)
 911                 crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
 912 #ifdef WORDS_BIGENDIAN
 913         if (save_size > ext4_bg_size)
 914                 crc3 = ext2fs_crc16(crc3, (char *)save_desc + ext4_bg_size,
 915                                     save_size - ext4_bg_size);
 916 #endif
 917
 918         printf("%s UUID %s=%04x, grp %u=%04x: %04x=%04x\n",
 919                msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2, crc3,
 920                ext2fs_group_desc_csum(fs, group));
 921 }
 922
 923 unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
 924                               0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };
 925
 926 int main(int argc, char **argv)
 927 {
 928         struct ext2_super_block param;
 929         errcode_t               retval;
 930         ext2_filsys             fs;
 931         int                     i;
 932         __u16 csum1, csum2, csum_known = 0xd3a4;
 933
 934         memset(&param, 0, sizeof(param));
 935         ext2fs_blocks_count_set(&param, 32768);
 936 #if 0
 937         param.s_feature_incompat |= EXT4_FEATURE_INCOMPAT_64BIT;
 938         param.s_desc_size = 128;
 939         csum_known = 0x5b6e;
 940 #endif
 941
 942         retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, &param,
 943                                    test_io_manager, &fs);
 944         if (retval) {
 945                 com_err("setup", retval,
 946                         "While initializing filesystem");
 947                 exit(1);
 948         }
 949         memcpy(fs->super->s_uuid, sb_uuid, 16);
 950         fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
 951
 952         for (i=0; i < fs->group_desc_count; i++) {
 953                 ext2fs_block_bitmap_loc_set(fs, i, 124);
 954                 ext2fs_inode_bitmap_loc_set(fs, i, 125);
 955                 ext2fs_inode_table_loc_set(fs, i, 126);
 956                 ext2fs_bg_free_blocks_count_set(fs, i, 31119);
 957                 ext2fs_bg_free_inodes_count_set(fs, i, 15701);
 958                 ext2fs_bg_used_dirs_count_set(fs, i, 2);
 959                 ext2fs_bg_flags_zap(fs, i);
 960         };
 961
 962         csum1 = ext2fs_group_desc_csum(fs, 0);
 963         print_csum("csum0000", fs, 0);
 964
 965         if (csum1 != csum_known) {
 966                 printf("checksum for group 0 should be %04x\n", csum_known);
 967                 exit(1);
 968         }
 969         csum2 = ext2fs_group_desc_csum(fs, 1);
 970         print_csum("csum0001", fs, 1);
 971         if (csum1 == csum2) {
 972                 printf("checksums for different groups shouldn't match\n");
 973                 exit(1);
 974         }
 975         csum2 = ext2fs_group_desc_csum(fs, 2);
 976         print_csum("csumffff", fs, 2);
 977         if (csum1 == csum2) {
 978                 printf("checksums for different groups shouldn't match\n");
 979                 exit(1);
 980         }
 981         ext2fs_bg_checksum_set(fs, 0, csum1);
 982         csum2 = ext2fs_group_desc_csum(fs, 0);
 983         print_csum("csum_set", fs, 0);
 984         if (csum1 != csum2) {
 985                 printf("checksums should not depend on checksum field\n");
 986                 exit(1);
 987         }
 988         if (!ext2fs_group_desc_csum_verify(fs, 0)) {
 989                 printf("checksums should verify against gd_checksum\n");
 990                 exit(1);
 991         }
 992         memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
 993         print_csum("new_uuid", fs, 0);
 994         if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
 995                 printf("checksums for different filesystems shouldn't match\n");
 996                 exit(1);
 997         }
 998         csum1 = ext2fs_group_desc_csum(fs, 0);
 999         ext2fs_bg_checksum_set(fs, 0, csum1);
1000         print_csum("csum_new", fs, 0);
1001         ext2fs_bg_free_blocks_count_set(fs, 0, 1);
1002         csum2 = ext2fs_group_desc_csum(fs, 0);
1003         print_csum("csum_blk", fs, 0);
1004         if (csum1 == csum2) {
1005                 printf("checksums for different data shouldn't match\n");
1006                 exit(1);
1007         }
1008
1009         return 0;
1010 }
1011 #endif