The inode btree verifier code is shared between the inode btree and
free inode btree because the underlying metadata formats are
essentially equivalent. A side effect of this is that the verifier
cannot determine whether a particular btree block should have an
inobt or finobt magic value.
This logic allows an unfortunate xfs_repair bug to escape detection
where certain level > 0 nodes of the finobt are stamped with inobt
magic by xfs_repair finobt reconstruction. This is fortunately not a
severe problem since the inode btree magic values do not contribute
to any changes in kernel behavior, but we do need a means to detect
and prevent this problem in the future.
Add a field to xfs_buf_ops to store the v4 and v5 superblock magic
values expected by a particular verifier. Add a helper to check an
on-disk magic value against the value expected by the verifier. Call
the helper from the shared [f]inobt verifier code for magic value
verification. This ensures that the inode btree blocks each have the
appropriate magic value based on specific tree type and superblock
version.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_ialloc_btree.c | 15 ++++++---------
fs/xfs/xfs_buf.h | 19 +++++++++++++++++++
2 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 798269eb4767..c57ecb6b1255 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -260,6 +260,9 @@ xfs_inobt_verify(
xfs_failaddr_t fa;
unsigned int level;
+ if (!xfs_verify_magic(bp, block->bb_magic))
+ return __this_address;
+
/*
* During growfs operations, we can't verify the exact owner as the
* perag is not fully initialised and hence not attached to the buffer.
@@ -270,18 +273,10 @@ xfs_inobt_verify(
* but beware of the landmine (i.e. need to check pag->pagi_init) if we
* ever do.
*/
- switch (block->bb_magic) {
- case cpu_to_be32(XFS_IBT_CRC_MAGIC):
- case cpu_to_be32(XFS_FIBT_CRC_MAGIC):
+ if (xfs_sb_version_hascrc(&mp->m_sb)) {
fa = xfs_btree_sblock_v5hdr_verify(bp);
if (fa)
return fa;
- /* fall through */
- case cpu_to_be32(XFS_IBT_MAGIC):
- case cpu_to_be32(XFS_FIBT_MAGIC):
- break;
- default:
- return __this_address;
}
/* level verification */
@@ -328,6 +323,7 @@ xfs_inobt_write_verify(
const struct xfs_buf_ops xfs_inobt_buf_ops = {
.name = "xfs_inobt",
+ .magic = { XFS_IBT_MAGIC, XFS_IBT_CRC_MAGIC },
.verify_read = xfs_inobt_read_verify,
.verify_write = xfs_inobt_write_verify,
.verify_struct = xfs_inobt_verify,
@@ -335,6 +331,7 @@ const struct xfs_buf_ops xfs_inobt_buf_ops = {
const struct xfs_buf_ops xfs_finobt_buf_ops = {
.name = "xfs_finobt",
+ .magic = { XFS_FIBT_MAGIC, XFS_FIBT_CRC_MAGIC },
.verify_read = xfs_inobt_read_verify,
.verify_write = xfs_inobt_write_verify,
.verify_struct = xfs_inobt_verify,
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index b9f5511ea998..d8757eafba71 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -125,6 +125,7 @@ struct xfs_buf_map {
struct xfs_buf_ops {
char *name;
+ uint32_t magic[2];
void (*verify_read)(struct xfs_buf *);
void (*verify_write)(struct xfs_buf *);
xfs_failaddr_t (*verify_struct)(struct xfs_buf *bp);
@@ -387,4 +388,22 @@ extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
int xfs_buf_ensure_ops(struct xfs_buf *bp, const struct xfs_buf_ops *ops);
+/*
+ * Verify an on-disk magic value against the magic value specified in the
+ * verifier structure.
+ */
+static inline bool
+xfs_buf_ops_verify_magic(
+ struct xfs_buf *bp,
+ __be32 dmagic,
+ bool crc)
+{
+ if (unlikely(WARN_ON(!bp->b_ops || !bp->b_ops->magic[crc])))
+ return false;
+ return dmagic == cpu_to_be32(bp->b_ops->magic[crc]);
+}
+#define xfs_verify_magic(bp, dmagic) \
+ xfs_buf_ops_verify_magic(bp, dmagic, \
+ xfs_sb_version_hascrc(&bp->b_target->bt_mount->m_sb))
+
#endif /* __XFS_BUF_H__ */
--
2.17.2
