[PATCH 45/51] e2fsck: Check revoke block checksum during recovery

["Darrick J. Wong" <djwong@us.ibm.com>]

Verify the revoke block checksum when recovering the journal.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
 e2fsck/recovery.c |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)


diff --git a/e2fsck/recovery.c b/e2fsck/recovery.c
index b669941..60c8ceb 100644
--- a/e2fsck/recovery.c
+++ b/e2fsck/recovery.c
@@ -715,6 +715,27 @@ static int do_one_pass(journal_t *journal,
 	return err;
 }
 
+static int jbd2_revoke_block_csum_verify(journal_t *j,
+					 void *buf)
+{
+	struct journal_revoke_tail *tail;
+	__u32 provided, calculated;
+
+	if (!JFS_HAS_INCOMPAT_FEATURE(j, JFS_FEATURE_INCOMPAT_CSUM_V2))
+		return 1;
+
+	tail = (struct journal_revoke_tail *)(buf + j->j_blocksize -
+			sizeof(struct journal_revoke_tail));
+	provided = tail->r_checksum;
+	tail->r_checksum = 0;
+	calculated = ext2fs_crc32c_le(~0, j->j_superblock->s_uuid,
+				      sizeof(j->j_superblock->s_uuid));
+	calculated = ext2fs_crc32c_le(calculated, buf, j->j_blocksize);
+	tail->r_checksum = provided;
+
+	provided = ext2fs_be32_to_cpu(provided);
+	return provided == calculated;
+}
 
 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 
@@ -729,6 +750,9 @@ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 	offset = sizeof(journal_revoke_header_t);
 	max = be32_to_cpu(header->r_count);
 
+	if (!jbd2_revoke_block_csum_verify(journal, header))
+		return -EINVAL;
+
 	if (JFS_HAS_INCOMPAT_FEATURE(journal, JFS_FEATURE_INCOMPAT_64BIT))
 		record_len = 8;