Continuing efforts to provide hardening of FFS. This change adds a

check hash to the filesystem inodes. Access attempts to files
associated with an inode with an invalid check hash will fail with
EINVAL (Invalid argument). Access is reestablished after an fsck
is run to find and validate the inodes with invalid check-hashes.
This check avoids a class of filesystem panics related to corrupted
inodes. The hash is done using crc32c.

Note this check-hash is for the inode itself and not any of its
indirect blocks. Check-hash validation may be extended to also
cover indirect block pointers, but that will be a separate (and
more costly) feature.

Check hashes are added only to UFS2 and not to UFS1 as UFS1 is
primarily used in embedded systems with small memories and low-powered
processors which need as light-weight a filesystem as possible.

Reviewed by:  kib
Tested by:    Peter Holm
Sponsored by: Netflix

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/libufs/libufs.h b/lib/libufs/libufs.h
index 9d1e7355c2f7..44eaed83ccbd 100644
--- a/lib/libufs/libufs.h
+++ b/lib/libufs/libufs.h
@@ -116,6 +116,8 @@ int	ffs_sbget(void *, struct fs **, off_t, char *,
 	    int (*)(void *, off_t, void **, int));
 int	ffs_sbput(void *, struct fs *, off_t,
 	    int (*)(void *, off_t, void *, int));
+void	ffs_update_dinode_ckhash(struct fs *, struct ufs2_dinode *);
+int	ffs_verify_dinode_ckhash(struct fs *, struct ufs2_dinode *);
 
 /*
  * Request standard superblock location in ffs_sbget