e2fsck: check descriptor block checksum when recovering journal

Verify the descriptor block checksum when recovering a journal.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/e2fsck/recovery.c b/e2fsck/recovery.c
index 8bf4401..208e1cb 100644 (file)
--- a/e2fsck/recovery.c
+++ b/e2fsck/recovery.c
@@ -174,6 +174,27 @@ static int jread(struct buffer_head **bhp, journal_t *journal,
        return 0;
 }
 
+static int jbd2_descr_block_csum_verify(journal_t *j,
+                                       void *buf)
+{
+       struct journal_block_tail *tail;
+       __u32 provided, calculated;
+
+       if (!JFS_HAS_INCOMPAT_FEATURE(j, JFS_FEATURE_INCOMPAT_CSUM_V2))
+               return 1;
+
+       tail = (struct journal_block_tail *)(buf + j->j_blocksize -
+                       sizeof(struct journal_block_tail));
+       provided = tail->t_checksum;
+       tail->t_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->t_checksum = provided;
+
+       provided = ext2fs_be32_to_cpu(provided);
+       return provided == calculated;
+}
 
 /*
  * Count the number of in-use tags in a journal descriptor block.
@@ -186,6 +207,9 @@ static int count_tags(journal_t *journal, struct buffer_head *bh)
        int                     nr = 0, size = journal->j_blocksize;
        int                     tag_bytes = journal_tag_bytes(journal);
 
+       if (JFS_HAS_INCOMPAT_FEATURE(journal, JFS_FEATURE_INCOMPAT_CSUM_V2))
+               size -= sizeof(struct journal_block_tail);
+
        tagp = &bh->b_data[sizeof(journal_header_t)];
 
        while ((tagp - bh->b_data + tag_bytes) <= size) {
@@ -362,6 +386,7 @@ static int do_one_pass(journal_t *journal,
        int                     blocktype;
        int                     tag_bytes = journal_tag_bytes(journal);
        __u32                   crc32_sum = ~0; /* Transactional Checksums */
+       int                     descr_csum_size = 0;
 
        /* Precompute the maximum metadata descriptors in a descriptor block */
        int                     MAX_BLOCKS_PER_DESC;
@@ -452,6 +477,18 @@ static int do_one_pass(journal_t *journal,
 
                switch(blocktype) {
                case JFS_DESCRIPTOR_BLOCK:
+                       /* Verify checksum first */
+                       if (JFS_HAS_INCOMPAT_FEATURE(journal,
+                                       JFS_FEATURE_INCOMPAT_CSUM_V2))
+                               descr_csum_size =
+                                       sizeof(struct journal_block_tail);
+                       if (descr_csum_size > 0 &&
+                           !jbd2_descr_block_csum_verify(journal,
+                                                         bh->b_data)) {
+                               err = -EIO;
+                               goto failed;
+                       }
+
                        /* If it is a valid descriptor block, replay it
                         * in pass REPLAY; if journal_checksums enabled, then
                         * calculate checksums in PASS_SCAN, otherwise,
@@ -482,7 +519,7 @@ static int do_one_pass(journal_t *journal,
 
                        tagp = &bh->b_data[sizeof(journal_header_t)];
                        while ((tagp - bh->b_data + tag_bytes)
-                              <= journal->j_blocksize) {
+                              <= journal->j_blocksize - descr_csum_size) {
                                unsigned long long io_block;
 
                                tag = (journal_block_tag_t *) tagp;