xfs: validate metadata LSNs against log on v5 superblocks

Since the onset of v5 superblocks, the LSN of the last modification has
been included in a variety of on-disk data structures. This LSN is used
to provide log recovery ordering guarantees (e.g., to ensure an older
log recovery item is not replayed over a newer target data structure).

While this works correctly from the point a filesystem is formatted and
mounted, userspace tools have some problematic behaviors that defeat
this mechanism. For example, xfs_repair historically zeroes out the log
unconditionally (regardless of whether corruption is detected). If this
occurs, the LSN of the filesystem is reset and the log is now in a
problematic state with respect to on-disk metadata structures that might
have a larger LSN. Until either the log catches up to the highest
previously used metadata LSN or each affected data structure is modified
and written out without incident (which resets the metadata LSN), log
recovery is susceptible to filesystem corruption.

This problem is ultimately addressed and repaired in the associated
userspace tools. The kernel is still responsible to detect the problem
and notify the user that something is wrong. Check the superblock LSN at
mount time and fail the mount if it is invalid. From that point on,
trigger verifier failure on any metadata I/O where an invalid LSN is
detected. This results in a filesystem shutdown and guarantees that we
do not log metadata changes with invalid LSNs on disk. Since this is a
known issue with a known recovery path, present a warning to instruct
the user how to recover.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

11 files changed, 65 insertions, 7 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index ffad7f20342f..d39e6d8a4949 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -482,7 +482,9 @@ xfs_agfl_verify(
 		    be32_to_cpu(agfl->agfl_bno[i]) >= mp->m_sb.sb_agblocks)
 			return false;
 	}
-	return true;
+
+	return xfs_log_check_lsn(mp,
+				 be64_to_cpu(XFS_BUF_TO_AGFL(bp)->agfl_lsn));
 }
 
 static void
@@ -2259,9 +2261,13 @@ xfs_agf_verify(
  {
 	struct xfs_agf	*agf = XFS_BUF_TO_AGF(bp);
 
-	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid))
+	if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		if (!uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
+		if (!xfs_log_check_lsn(mp,
+				be64_to_cpu(XFS_BUF_TO_AGF(bp)->agf_lsn)))
+			return false;
+	}
 
 	if (!(agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
 	      XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 33df52d97ec7..aa187f7ba2dd 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -41,6 +41,7 @@
 #include "xfs_buf_item.h"
 #include "xfs_cksum.h"
 #include "xfs_dir2.h"
+#include "xfs_log.h"
 
 
 /*
@@ -266,6 +267,8 @@ xfs_attr3_leaf_verify(
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(hdr3->info.lsn)))
+			return false;
 	} else {
 		if (ichdr.magic != XFS_ATTR_LEAF_MAGIC)
 			return false;
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index f7d7ee7a2607..235d026c7f9c 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -32,6 +32,7 @@
 #include "xfs_trace.h"
 #include "xfs_cksum.h"
 #include "xfs_alloc.h"
+#include "xfs_log.h"
 
 /*
  * Cursor allocation zone.
@@ -243,8 +244,14 @@ bool
 xfs_btree_lblock_verify_crc(
 	struct xfs_buf		*bp)
 {
-	if (xfs_sb_version_hascrc(&bp->b_target->bt_mount->m_sb))
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(block->bb_u.l.bb_lsn)))
+			return false;
 		return xfs_buf_verify_cksum(bp, XFS_BTREE_LBLOCK_CRC_OFF);
+	}
 
 	return true;
 }
@@ -275,8 +282,14 @@ bool
 xfs_btree_sblock_verify_crc(
 	struct xfs_buf		*bp)
 {
-	if (xfs_sb_version_hascrc(&bp->b_target->bt_mount->m_sb))
+	struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(block->bb_u.s.bb_lsn)))
+			return false;
 		return xfs_buf_verify_cksum(bp, XFS_BTREE_SBLOCK_CRC_OFF);
+	}
 
 	return true;
 }
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index be43248a5822..e89a0f8f827c 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -39,6 +39,7 @@
 #include "xfs_trace.h"
 #include "xfs_cksum.h"
 #include "xfs_buf_item.h"
+#include "xfs_log.h"
 
 /*
  * xfs_da_btree.c
@@ -150,6 +151,8 @@ xfs_da3_node_verify(
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(hdr3->info.lsn)))
+			return false;
 	} else {
 		if (ichdr.magic != XFS_DA_NODE_MAGIC)
 			return false;
@@ -322,6 +325,7 @@ xfs_da3_node_create(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		struct xfs_da3_node_hdr *hdr3 = bp->b_addr;
 
+		memset(hdr3, 0, sizeof(struct xfs_da3_node_hdr));
 		ichdr.magic = XFS_DA3_NODE_MAGIC;
 		hdr3->info.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->info.owner = cpu_to_be64(args->dp->i_ino);
diff --git a/fs/xfs/libxfs/xfs_dir2_block.c b/fs/xfs/libxfs/xfs_dir2_block.c
index 4778d1dd511a..9c10e2b8cfcb 100644
--- a/fs/xfs/libxfs/xfs_dir2_block.c
+++ b/fs/xfs/libxfs/xfs_dir2_block.c
@@ -34,6 +34,7 @@
 #include "xfs_error.h"
 #include "xfs_trace.h"
 #include "xfs_cksum.h"
+#include "xfs_log.h"
 
 /*
  * Local function prototypes.
@@ -71,6 +72,8 @@ xfs_dir3_block_verify(
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(hdr3->lsn)))
+			return false;
 	} else {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR2_BLOCK_MAGIC))
 			return false;
diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 824131e71bc5..af71a84f343c 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -31,6 +31,7 @@
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_cksum.h"
+#include "xfs_log.h"
 
 /*
  * Check the consistency of the data block.
@@ -224,6 +225,8 @@ xfs_dir3_data_verify(
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(hdr3->lsn)))
+			return false;
 	} else {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR2_DATA_MAGIC))
 			return false;
diff --git a/fs/xfs/libxfs/xfs_dir2_leaf.c b/fs/xfs/libxfs/xfs_dir2_leaf.c
index f300240ebb8d..3923e1f94697 100644
--- a/fs/xfs/libxfs/xfs_dir2_leaf.c
+++ b/fs/xfs/libxfs/xfs_dir2_leaf.c
@@ -33,6 +33,7 @@
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_cksum.h"
+#include "xfs_log.h"
 
 /*
  * Local function declarations.
@@ -164,6 +165,8 @@ xfs_dir3_leaf_verify(
 			return false;
 		if (be64_to_cpu(leaf3->info.blkno) != bp->b_bn)
 			return false;
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(leaf3->info.lsn)))
+			return false;
 	} else {
 		if (leaf->hdr.info.magic != cpu_to_be16(magic))
 			return false;
diff --git a/fs/xfs/libxfs/xfs_dir2_node.c b/fs/xfs/libxfs/xfs_dir2_node.c
index cc28e924545b..70b0cb2fd556 100644
--- a/fs/xfs/libxfs/xfs_dir2_node.c
+++ b/fs/xfs/libxfs/xfs_dir2_node.c
@@ -33,6 +33,7 @@
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_cksum.h"
+#include "xfs_log.h"
 
 /*
  * Function declarations.
@@ -97,6 +98,8 @@ xfs_dir3_free_verify(
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;
+		if (!xfs_log_check_lsn(mp, be64_to_cpu(hdr3->lsn)))
+			return false;
 	} else {
 		if (hdr->magic != cpu_to_be32(XFS_DIR2_FREE_MAGIC))
 			return false;
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 54deb2d12ac6..70c1db99f6a7 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -38,6 +38,7 @@
 #include "xfs_icreate_item.h"
 #include "xfs_icache.h"
 #include "xfs_trace.h"
+#include "xfs_log.h"
 
 
 /*
@@ -2500,9 +2501,14 @@ xfs_agi_verify(
 	struct xfs_mount *mp = bp->b_target->bt_mount;
 	struct xfs_agi	*agi = XFS_BUF_TO_AGI(bp);
 
-	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid))
+	if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		if (!uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid))
+			return false;
+		if (!xfs_log_check_lsn(mp,
+				be64_to_cpu(XFS_BUF_TO_AGI(bp)->agi_lsn)))
 			return false;
+	}
+
 	/*
 	 * Validate the magic number of the agi block.
 	 */
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 47425140f343..a0b071d881a0 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -35,6 +35,7 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_alloc_btree.h"
 #include "xfs_ialloc_btree.h"
+#include "xfs_log.h"
 
 /*
  * Physical superblock buffer manipulations. Shared with libxfs in userspace.
@@ -163,6 +164,15 @@ xfs_mount_validate_sb(
 "Filesystem can not be safely mounted by this kernel.");
 			return -EINVAL;
 		}
+	} else if (xfs_sb_version_hascrc(sbp)) {
+		/*
+		 * We can't read verify the sb LSN because the read verifier is
+		 * called before the log is allocated and processed. We know the
+		 * log is set up before write verifier (!check_version) calls,
+		 * so just check it here.
+		 */
+		if (!xfs_log_check_lsn(mp, sbp->sb_lsn))
+			return -EFSCORRUPTED;
 	}
 
 	if (xfs_sb_version_has_pquotino(sbp)) {
diff --git a/fs/xfs/libxfs/xfs_symlink_remote.c b/fs/xfs/libxfs/xfs_symlink_remote.c
index b9884aab46d3..cb6fd20a4d3d 100644
--- a/fs/xfs/libxfs/xfs_symlink_remote.c
+++ b/fs/xfs/libxfs/xfs_symlink_remote.c
@@ -31,6 +31,7 @@
 #include "xfs_cksum.h"
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
+#include "xfs_log.h"
 
 
 /*
@@ -60,6 +61,7 @@ xfs_symlink_hdr_set(
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
 		return 0;
 
+	memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
 	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
 	dsl->sl_offset = cpu_to_be32(offset);
 	dsl->sl_bytes = cpu_to_be32(size);
@@ -116,6 +118,8 @@ xfs_symlink_verify(
 		return false;
 	if (dsl->sl_owner == 0)
 		return false;
+	if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
+		return false;
 
 	return true;
 }