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jbd2: checksum journal superblock 

Calculate and verify a checksum covering the journal superblock.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong 2012-05-27 08:08:22 -04:00 committed by Theodore Ts'o
parent 01b5adcebb
commit 4fd5ea43bc
2 changed files with 50 additions and 0 deletions
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47
fs/jbd2/journal.c
View File

@ -106,6 +106,34 @@ int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
}
static __u32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
{
__u32 csum, old_csum;
old_csum = sb->s_checksum;
sb->s_checksum = 0;
csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t));
sb->s_checksum = old_csum;
return cpu_to_be32(csum);
}
int jbd2_superblock_csum_verify(journal_t *j, journal_superblock_t *sb)
{
if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
return 1;
return sb->s_checksum == jbd2_superblock_csum(j, sb);
}
void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb)
{
if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
return;
sb->s_checksum = jbd2_superblock_csum(j, sb);
}
/*
* Helper function used to manage commit timeouts
*/
@ -1357,6 +1385,7 @@ static void jbd2_journal_update_sb_errno(journal_t *journal)
jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
journal->j_errno);
sb->s_errno = cpu_to_be32(journal->j_errno);
jbd2_superblock_csum_set(journal, sb);
read_unlock(&journal->j_state_lock);
jbd2_write_superblock(journal, WRITE_SYNC);
@ -1449,6 +1478,17 @@ static int journal_get_superblock(journal_t *journal)
}
}
/* Check superblock checksum */
if (!jbd2_superblock_csum_verify(journal, sb)) {
printk(KERN_ERR "JBD: journal checksum error\n");
goto out;
}
/* Precompute checksum seed for all metadata */
if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
sizeof(sb->s_uuid));
set_buffer_verified(bh);
return 0;
@ -1732,6 +1772,13 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
return 0;
}
}
/* Precompute checksum seed for all metadata */
if (JBD2_HAS_INCOMPAT_FEATURE(journal,
JBD2_FEATURE_INCOMPAT_CSUM_V2))
journal->j_csum_seed = jbd2_chksum(journal, ~0,
sb->s_uuid,
sizeof(sb->s_uuid));
}
/* If enabling v1 checksums, downgrade superblock */

3
include/linux/jbd2.h
View File

@ -969,6 +969,9 @@ struct journal_s
/* Reference to checksum algorithm driver via cryptoapi */
struct crypto_shash *j_chksum_driver;
/* Precomputed journal UUID checksum for seeding other checksums */
__u32 j_csum_seed;
};
/*