jbd2: checksum descriptor blocks
Calculate and verify a checksum of each descriptor block.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 728ecd0..066ee60 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -174,6 +174,25 @@
return 0;
}
+static int jbd2_descr_block_csum_verify(journal_t *j,
+ void *buf)
+{
+ struct jbd2_journal_block_tail *tail;
+ __u32 provided, calculated;
+
+ if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+ return 1;
+
+ tail = (struct jbd2_journal_block_tail *)(buf + j->j_blocksize -
+ sizeof(struct jbd2_journal_block_tail));
+ provided = tail->t_checksum;
+ tail->t_checksum = 0;
+ calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
+ tail->t_checksum = provided;
+
+ provided = be32_to_cpu(provided);
+ return provided == calculated;
+}
/*
* Count the number of in-use tags in a journal descriptor block.
@@ -186,6 +205,9 @@
int nr = 0, size = journal->j_blocksize;
int tag_bytes = journal_tag_bytes(journal);
+ if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+ size -= sizeof(struct jbd2_journal_block_tail);
+
tagp = &bh->b_data[sizeof(journal_header_t)];
while ((tagp - bh->b_data + tag_bytes) <= size) {
@@ -366,6 +388,7 @@
int blocktype;
int tag_bytes = journal_tag_bytes(journal);
__u32 crc32_sum = ~0; /* Transactional Checksums */
+ int descr_csum_size = 0;
/*
* First thing is to establish what we expect to find in the log
@@ -451,6 +474,18 @@
switch(blocktype) {
case JBD2_DESCRIPTOR_BLOCK:
+ /* Verify checksum first */
+ if (JBD2_HAS_INCOMPAT_FEATURE(journal,
+ JBD2_FEATURE_INCOMPAT_CSUM_V2))
+ descr_csum_size =
+ sizeof(struct jbd2_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,
@@ -481,7 +516,7 @@
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 io_block;
tag = (journal_block_tag_t *) tagp;