xfs: verify btree blocks as they are read from disk

Add an btree block verify callback function and pass it into the
buffer read functions. Because each different btree block type
requires different verification, add a function to the ops structure
that is called from the generic code.

Also, propagate the verification callback functions through the
readahead functions, and into the external bmap and bulkstat inode
readahead code that uses the generic btree buffer read functions.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Phil White <pwhite@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index 862084a47a7e..bddca9b92869 100644
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -36,6 +36,7 @@
 #include "xfs_bmap.h"
 #include "xfs_error.h"
 #include "xfs_quota.h"
+#include "xfs_trace.h"
 
 /*
  * Determine the extent state.
@@ -707,6 +708,51 @@ xfs_bmbt_key_diff(
                                       cur->bc_rec.b.br_startoff;
 }
 
+void
+xfs_bmbt_read_verify(
+        struct xfs_buf          *bp)
+{
+        struct xfs_mount        *mp = bp->b_target->bt_mount;
+        struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
+        unsigned int            level;
+        int                     lblock_ok; /* block passes checks */
+
+        /* magic number and level verification.
+         *
+         * We don't know waht fork we belong to, so just verify that the level
+         * is less than the maximum of the two. Later checks will be more
+         * precise.
+         */
+        level = be16_to_cpu(block->bb_level);
+        lblock_ok = block->bb_magic == cpu_to_be32(XFS_BMAP_MAGIC) &&
+                    level < max(mp->m_bm_maxlevels[0], mp->m_bm_maxlevels[1]);
+
+        /* numrecs verification */
+        lblock_ok = lblock_ok &&
+                be16_to_cpu(block->bb_numrecs) <= mp->m_bmap_dmxr[level != 0];
+
+        /* sibling pointer verification */
+        lblock_ok = lblock_ok &&
+                block->bb_u.l.bb_leftsib &&
+                (block->bb_u.l.bb_leftsib == cpu_to_be64(NULLDFSBNO) ||
+                 XFS_FSB_SANITY_CHECK(mp,
+                        be64_to_cpu(block->bb_u.l.bb_leftsib))) &&
+                block->bb_u.l.bb_rightsib &&
+                (block->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO) ||
+                 XFS_FSB_SANITY_CHECK(mp,
+                        be64_to_cpu(block->bb_u.l.bb_rightsib)));
+
+        if (!lblock_ok) {
+                trace_xfs_btree_corrupt(bp, _RET_IP_);
+                XFS_CORRUPTION_ERROR("xfs_bmbt_read_verify",
+                                        XFS_ERRLEVEL_LOW, mp, block);
+                xfs_buf_ioerror(bp, EFSCORRUPTED);
+        }
+
+        bp->b_iodone = NULL;
+        xfs_buf_ioend(bp, 0);
+}
+
 #ifdef DEBUG
 STATIC int
 xfs_bmbt_keys_inorder(
@@ -746,6 +792,7 @@ static const struct xfs_btree_ops xfs_bmbt_ops = {
         .init_rec_from_cur      = xfs_bmbt_init_rec_from_cur,
         .init_ptr_from_cur      = xfs_bmbt_init_ptr_from_cur,
         .key_diff               = xfs_bmbt_key_diff,
+        .read_verify            = xfs_bmbt_read_verify,
 #ifdef DEBUG
         .keys_inorder           = xfs_bmbt_keys_inorder,
         .recs_inorder           = xfs_bmbt_recs_inorder,