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e2fsck: check journal superblock checksum prior to recovery 

Ensure that the journal superblock passes checksum before recovering the
filesystem.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
pu
Darrick J. Wong 2012-08-02 20:47:45 -04:00 committed by Theodore Ts'o
parent 382fad03a2
commit b279594950
1 changed files with 59 additions and 0 deletions
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59
e2fsck/journal.c
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@ -40,6 +40,53 @@ static int bh_count = 0;
*/
#undef USE_INODE_IO
/* Checksumming functions */
int e2fsck_journal_verify_csum_type(journal_t *j, journal_superblock_t *jsb)
{
if (!JFS_HAS_INCOMPAT_FEATURE(j, JFS_FEATURE_INCOMPAT_CSUM_V2))
return 1;
return jsb->s_checksum_type == JBD2_CRC32C_CHKSUM;
}
static __u32 e2fsck_journal_sb_csum(journal_t *j, journal_superblock_t *jsb)
{
__u32 crc, old_crc;
old_crc = jsb->s_checksum;
jsb->s_checksum = 0;
crc = ext2fs_crc32c_le(~0, (unsigned char *)jsb,
sizeof(journal_superblock_t));
jsb->s_checksum = old_crc;
return crc;
}
int e2fsck_journal_sb_csum_verify(journal_t *j, journal_superblock_t *jsb)
{
__u32 provided, calculated;
if (!JFS_HAS_INCOMPAT_FEATURE(j, JFS_FEATURE_INCOMPAT_CSUM_V2))
return 1;
provided = ext2fs_be32_to_cpu(jsb->s_checksum);
calculated = e2fsck_journal_sb_csum(j, jsb);
return provided == calculated;
}
errcode_t e2fsck_journal_sb_csum_set(journal_t *j, journal_superblock_t *jsb)
{
__u32 crc;
if (!JFS_HAS_INCOMPAT_FEATURE(j, JFS_FEATURE_INCOMPAT_CSUM_V2))
return 0;
crc = e2fsck_journal_sb_csum(j, jsb);
jsb->s_checksum = ext2fs_cpu_to_be32(crc);
return 0;
}
/* Kernel compatibility functions for handling the journal. These allow us
* to use the recovery.c file virtually unchanged from the kernel, so we
* don't have to do much to keep kernel and user recovery in sync.
@ -561,6 +608,15 @@ static errcode_t e2fsck_journal_load(journal_t *journal)
if (JFS_HAS_RO_COMPAT_FEATURE(journal, ~JFS_KNOWN_ROCOMPAT_FEATURES))
return EXT2_ET_RO_UNSUPP_FEATURE;
/* Checksum v1 and v2 are mutually exclusive features. */
if (JFS_HAS_INCOMPAT_FEATURE(journal, JFS_FEATURE_INCOMPAT_CSUM_V2) &&
JFS_HAS_COMPAT_FEATURE(journal, JFS_FEATURE_COMPAT_CHECKSUM))
return EXT2_ET_CORRUPT_SUPERBLOCK;
if (!e2fsck_journal_verify_csum_type(journal, jsb) ||
!e2fsck_journal_sb_csum_verify(journal, jsb))
return EXT2_ET_CORRUPT_SUPERBLOCK;
/* We have now checked whether we know enough about the journal
* format to be able to proceed safely, so any other checks that
* fail we should attempt to recover from. */
@ -628,6 +684,7 @@ static void e2fsck_journal_reset_super(e2fsck_t ctx, journal_superblock_t *jsb,
for (i = 0; i < 4; i ++)
new_seq ^= u.val[i];
jsb->s_sequence = htonl(new_seq);
e2fsck_journal_sb_csum_set(journal, jsb);
mark_buffer_dirty(journal->j_sb_buffer);
ll_rw_block(WRITE, 1, &journal->j_sb_buffer);
@ -668,6 +725,7 @@ static void e2fsck_journal_release(e2fsck_t ctx, journal_t *journal,
jsb->s_sequence = htonl(journal->j_transaction_sequence);
if (reset)
jsb->s_start = 0; /* this marks the journal as empty */
e2fsck_journal_sb_csum_set(journal, jsb);
mark_buffer_dirty(journal->j_sb_buffer);
}
brelse(journal->j_sb_buffer);
@ -813,6 +871,7 @@ no_has_journal:
ctx->fs->super->s_state |= EXT2_ERROR_FS;
ext2fs_mark_super_dirty(ctx->fs);
journal->j_superblock->s_errno = 0;
e2fsck_journal_sb_csum_set(journal, journal->j_superblock);
mark_buffer_dirty(journal->j_sb_buffer);
}