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 int ext2fs_inode_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
  34                                     char *bitmap, int size)
  35 {
  36         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  37                         ext2fs_group_desc(fs, fs->group_desc, group);
  38         __u32 provided, calculated;
  39
  40         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
  41                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  42                 return 1;
  43         provided = gdp->bg_inode_bitmap_csum_lo;
  44         calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
  45                                       size);
  46         if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  47                 provided |= (__u32)gdp->bg_inode_bitmap_csum_hi << 16;
  48         else
  49                 calculated &= 0xFFFF;
  50
  51         return provided == calculated;
  52 }
  53
  54 errcode_t ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
  55                                        char *bitmap, int size)
  56 {
  57         __u32 crc;
  58         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  59                         ext2fs_group_desc(fs, fs->group_desc, group);
  60
  61         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
  62                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  63                 return 0;
  64
  65         crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
  66         gdp->bg_inode_bitmap_csum_lo = crc & 0xFFFF;
  67         if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  68                 gdp->bg_inode_bitmap_csum_hi = crc >> 16;
  69
  70         return 0;
  71 }
  72
  73 int ext2fs_block_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
  74                                     char *bitmap, int size)
  75 {
  76         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  77                         ext2fs_group_desc(fs, fs->group_desc, group);
  78         __u32 provided, calculated;
  79
  80         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
  81                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  82                 return 1;
  83         provided = gdp->bg_block_bitmap_csum_lo;
  84         calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
  85                                       size);
  86         if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
  87                 provided |= (__u32)gdp->bg_block_bitmap_csum_hi << 16;
  88         else
  89                 calculated &= 0xFFFF;
  90
  91         return provided == calculated;
  92 }
  93
  94 errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
  95                                        char *bitmap, int size)
  96 {
  97         __u32 crc;
  98         struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  99                         ext2fs_group_desc(fs, fs->group_desc, group);
 100
 101         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 102                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 103                 return 0;
 104
 105         crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
 106         gdp->bg_block_bitmap_csum_lo = crc & 0xFFFF;
 107         if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
 108                 gdp->bg_block_bitmap_csum_hi = crc >> 16;
 109
 110         return 0;
 111 }
 112
 113 static errcode_t ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
 114                                struct ext2_inode_large *inode,
 115                                __u32 *crc, int has_hi)
 116 {
 117         __u32 gen;
 118         struct ext2_inode_large *desc = inode;
 119         size_t size = fs->super->s_inode_size;
 120         __u16 old_lo;
 121         __u16 old_hi = 0;
 122
 123         old_lo = inode->i_checksum_lo;
 124         inode->i_checksum_lo = 0;
 125         if (has_hi) {
 126                 old_hi = inode->i_checksum_hi;
 127                 inode->i_checksum_hi = 0;
 128         }
 129
 130         inum = ext2fs_cpu_to_le32(inum);
 131         gen = inode->i_generation;
 132         *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
 133                                 sizeof(inum));
 134         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
 135         *crc = ext2fs_crc32c_le(*crc, (unsigned char *)desc, size);
 136
 137         inode->i_checksum_lo = old_lo;
 138         if (has_hi)
 139                 inode->i_checksum_hi = old_hi;
 140         return 0;
 141 }
 142
 143 int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
 144                              struct ext2_inode_large *inode)
 145 {
 146         errcode_t retval;
 147         __u32 provided, calculated;
 148         int has_hi;
 149
 150         if (fs->super->s_creator_os != EXT2_OS_LINUX ||
 151             !EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 152                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 153                 return 1;
 154
 155         has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
 156                   inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
 157
 158         provided = ext2fs_le16_to_cpu(inode->i_checksum_lo);
 159         retval = ext2fs_inode_csum(fs, inum, inode, &calculated, has_hi);
 160         if (retval)
 161                 return 0;
 162         if (has_hi) {
 163                 __u32 hi = ext2fs_le16_to_cpu(inode->i_checksum_hi);
 164                 provided |= hi << 16;
 165         } else
 166                 calculated &= 0xFFFF;
 167
 168         return provided == calculated;
 169 }
 170
 171 errcode_t ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
 172                            struct ext2_inode_large *inode)
 173 {
 174         errcode_t retval;
 175         __u32 crc;
 176         int has_hi;
 177
 178         if (fs->super->s_creator_os != EXT2_OS_LINUX ||
 179             !EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 180                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 181                 return 0;
 182
 183         has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
 184                   inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
 185
 186         retval = ext2fs_inode_csum(fs, inum, inode, &crc, has_hi);
 187         if (retval)
 188                 return retval;
 189         inode->i_checksum_lo = ext2fs_cpu_to_le16(crc & 0xFFFF);
 190         if (has_hi)
 191                 inode->i_checksum_hi = ext2fs_cpu_to_le16(crc >> 16);
 192         return 0;
 193 }
 194
 195 __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 196 {
 197         __u16 crc = 0;
 198         struct ext2_group_desc *desc;
 199         size_t size;
 200
 201         size = fs->super->s_desc_size;
 202         if (size < EXT2_MIN_DESC_SIZE)
 203                 size = EXT2_MIN_DESC_SIZE;
 204         if (size > sizeof(struct ext4_group_desc)) {
 205                 /* This should never happen, but cap it for safety's sake */
 206                 size = sizeof(struct ext4_group_desc);
 207         }
 208
 209         desc = ext2fs_group_desc(fs, fs->group_desc, group);
 210
 211         if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
 212                 size_t offset = offsetof(struct ext2_group_desc, bg_checksum);
 213
 214 #ifdef WORDS_BIGENDIAN
 215                 struct ext4_group_desc swabdesc;
 216
 217                 /* Have to swab back to little-endian to do the checksum */
 218                 memcpy(&swabdesc, desc, size);
 219                 ext2fs_swap_group_desc2(fs,
 220                                         (struct ext2_group_desc *) &swabdesc);
 221                 desc = (struct ext2_group_desc *) &swabdesc;
 222
 223                 group = ext2fs_swab32(group);
 224 #endif
 225                 crc = ext2fs_crc16(~0, fs->super->s_uuid,
 226                                    sizeof(fs->super->s_uuid));
 227                 crc = ext2fs_crc16(crc, &group, sizeof(group));
 228                 crc = ext2fs_crc16(crc, desc, offset);
 229                 offset += sizeof(desc->bg_checksum); /* skip checksum */
 230                 /* for checksum of struct ext4_group_desc do the rest...*/
 231                 if (offset < size) {
 232                         crc = ext2fs_crc16(crc, (char *)desc + offset,
 233                                            size - offset);
 234                 }
 235         }
 236
 237         return crc;
 238 }
 239
 240 int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
 241 {
 242         if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 243                                        EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
 244             (ext2fs_bg_checksum(fs, group) !=
 245              ext2fs_group_desc_csum(fs, group)))
 246                 return 0;
 247
 248         return 1;
 249 }
 250
 251 void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
 252 {
 253         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 254                                         EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
 255                 return;
 256
 257         /* ext2fs_bg_checksum_set() sets the actual checksum field but
 258          * does not calculate the checksum itself. */
 259         ext2fs_bg_checksum_set(fs, group, ext2fs_group_desc_csum(fs, group));
 260 }
 261
 262 static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
 263                                    __u32 inodes_per_grp, dgrp_t grp_no)
 264 {
 265         ext2_ino_t i, start_ino, end_ino;
 266
 267         start_ino = grp_no * inodes_per_grp + 1;
 268         end_ino = start_ino + inodes_per_grp - 1;
 269
 270         for (i = end_ino; i >= start_ino; i--) {
 271                 if (ext2fs_fast_test_inode_bitmap2(bitmap, i))
 272                         return i - start_ino + 1;
 273         }
 274         return inodes_per_grp;
 275 }
 276
 277 /* update the bitmap flags, set the itable high watermark, and calculate
 278  * checksums for the group descriptors */
 279 errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
 280 {
 281         struct ext2_super_block *sb = fs->super;
 282         int dirty = 0;
 283         dgrp_t i;
 284
 285         if (!fs->inode_map)
 286                 return EXT2_ET_NO_INODE_BITMAP;
 287
 288         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 289                                         EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
 290                 return 0;
 291
 292         for (i = 0; i < fs->group_desc_count; i++) {
 293                 __u32 old_csum = ext2fs_bg_checksum(fs, i);
 294                 __u32 old_unused = ext2fs_bg_itable_unused(fs, i);
 295                 __u32 old_flags = ext2fs_bg_flags(fs, i);
 296                 __u32 old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i);
 297
 298                 if (old_free_inodes_count == sb->s_inodes_per_group) {
 299                         ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
 300                         ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group);
 301                 } else {
 302                         int unused =
 303                                 sb->s_inodes_per_group -
 304                                 find_last_inode_ingrp(fs->inode_map,
 305                                                       sb->s_inodes_per_group, i);
 306
 307                         ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT);
 308                         ext2fs_bg_itable_unused_set(fs, i, unused);
 309                 }
 310
 311                 ext2fs_group_desc_csum_set(fs, i);
 312                 if (old_flags != ext2fs_bg_flags(fs, i))
 313                         dirty = 1;
 314                 if (old_unused != ext2fs_bg_itable_unused(fs, i))
 315                         dirty = 1;
 316                 if (old_csum != ext2fs_bg_checksum(fs, i))
 317                         dirty = 1;
 318         }
 319         if (dirty)
 320                 ext2fs_mark_super_dirty(fs);
 321         return 0;
 322 }
 323
 324 #ifdef DEBUG
 325 #include "e2p/e2p.h"
 326
 327 void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
 328 {
 329         __u16 crc1, crc2, crc3;
 330         dgrp_t swabgroup;
 331         struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc, group);
 332         size_t size;
 333         struct ext2_super_block *sb = fs->super;
 334         int offset = offsetof(struct ext2_group_desc, bg_checksum);
 335 #ifdef WORDS_BIGENDIAN
 336         struct ext4_group_desc swabdesc;
 337 #endif
 338
 339         size = fs->super->s_desc_size;
 340         if (size < EXT2_MIN_DESC_SIZE)
 341                 size = EXT2_MIN_DESC_SIZE;
 342         if (size > sizeof(struct ext4_group_desc))
 343                 size = sizeof(struct ext4_group_desc);
 344 #ifdef WORDS_BIGENDIAN
 345         /* Have to swab back to little-endian to do the checksum */
 346         memcpy(&swabdesc, desc, size);
 347         ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
 348         desc = (struct ext2_group_desc *) &swabdesc;
 349
 350         swabgroup = ext2fs_swab32(group);
 351 #else
 352         swabgroup = group;
 353 #endif
 354
 355         crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
 356         crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
 357         crc3 = ext2fs_crc16(crc2, desc, offset);
 358         offset += sizeof(desc->bg_checksum); /* skip checksum */
 359         /* for checksum of struct ext4_group_desc do the rest...*/
 360         if (offset < size)
 361                 crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
 362
 363         printf("%s: UUID %s(%04x), grp %u(%04x): %04x=%04x\n",
 364                msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2, crc3,
 365                ext2fs_group_desc_csum(fs, group));
 366 }
 367
 368 unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
 369                               0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };
 370
 371 int main(int argc, char **argv)
 372 {
 373         struct ext2_super_block param;
 374         errcode_t               retval;
 375         ext2_filsys             fs;
 376         int                     i;
 377         __u16 csum1, csum2, csum_known = 0xd3a4;
 378
 379         memset(&param, 0, sizeof(param));
 380         ext2fs_blocks_count_set(&param, 32768);
 381
 382         retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, &param,
 383                                    test_io_manager, &fs);
 384         if (retval) {
 385                 com_err("setup", retval,
 386                         "While initializing filesystem");
 387                 exit(1);
 388         }
 389         memcpy(fs->super->s_uuid, sb_uuid, 16);
 390         fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
 391
 392         for (i=0; i < fs->group_desc_count; i++) {
 393                 ext2fs_block_bitmap_loc_set(fs, i, 124);
 394                 ext2fs_inode_bitmap_loc_set(fs, i, 125);
 395                 ext2fs_inode_table_loc_set(fs, i, 126);
 396                 ext2fs_bg_free_blocks_count_set(fs, i, 31119);
 397                 ext2fs_bg_free_inodes_count_set(fs, i, 15701);
 398                 ext2fs_bg_used_dirs_count_set(fs, i, 2);
 399                 ext2fs_bg_flags_zap(fs, i);
 400         };
 401
 402         csum1 = ext2fs_group_desc_csum(fs, 0);
 403         print_csum("csum0000", fs, 0);
 404
 405         if (csum1 != csum_known) {
 406                 printf("checksum for group 0 should be %04x\n", csum_known);
 407                 exit(1);
 408         }
 409         csum2 = ext2fs_group_desc_csum(fs, 1);
 410         print_csum("csum0001", fs, 1);
 411         if (csum1 == csum2) {
 412                 printf("checksums for different groups shouldn't match\n");
 413                 exit(1);
 414         }
 415         csum2 = ext2fs_group_desc_csum(fs, 2);
 416         print_csum("csumffff", fs, 2);
 417         if (csum1 == csum2) {
 418                 printf("checksums for different groups shouldn't match\n");
 419                 exit(1);
 420         }
 421         ext2fs_bg_checksum_set(fs, 0, csum1);
 422         csum2 = ext2fs_group_desc_csum(fs, 0);
 423         print_csum("csum_set", fs, 0);
 424         if (csum1 != csum2) {
 425                 printf("checksums should not depend on checksum field\n");
 426                 exit(1);
 427         }
 428         if (!ext2fs_group_desc_csum_verify(fs, 0)) {
 429                 printf("checksums should verify against gd_checksum\n");
 430                 exit(1);
 431         }
 432         memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
 433         print_csum("new_uuid", fs, 0);
 434         if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
 435                 printf("checksums for different filesystems shouldn't match\n");
 436                 exit(1);
 437         }
 438         csum1 = ext2fs_group_desc_csum(fs, 0);
 439         ext2fs_bg_checksum_set(fs, 0, csum1);
 440         print_csum("csum_new", fs, 0);
 441         ext2fs_bg_free_blocks_count_set(fs, 0, 1);
 442         csum2 = ext2fs_group_desc_csum(fs, 0);
 443         print_csum("csum_blk", fs, 0);
 444         if (csum1 == csum2) {
 445                 printf("checksums for different data shouldn't match\n");
 446                 exit(1);
 447         }
 448
 449         return 0;
 450 }
 451 #endif