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>

diff --git a/e2fsck/journal.c b/e2fsck/journal.c
index 767ea10..59ccc0e 100644 (file)
--- a/e2fsck/journal.c
+++ b/e2fsck/journal.c
@@ -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);
        }