From: Eric Snowberg <eric.snowberg@xxxxxxxxxx>
[ Upstream commit 18b44bc5a67275641fb26f2c54ba7eef80ac5950 ]
Commit db1d1e8b9867 ("IMA: use vfs_getattr_nosec to get the i_version")
partially closed an IMA integrity issue when directly modifying a file
on the lower filesystem. If the overlay file is first opened by a user
and later the lower backing file is modified by root, but the extended
attribute is NOT updated, the signature validation succeeds with the old
original signature.
Update the super_block s_iflags to SB_I_IMA_UNVERIFIABLE_SIGNATURE to
force signature reevaluation on every file access until a fine grained
solution can be found.
Signed-off-by: Eric Snowberg <eric.snowberg@xxxxxxxxxx>
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/overlayfs/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 5310271cf2e38..e18025b5c8872 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -2140,7 +2140,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ovl_trusted_xattr_handlers;
sb->s_fs_info = ofs;
sb->s_flags |= SB_POSIXACL;
- sb->s_iflags |= SB_I_SKIP_SYNC;
+ sb->s_iflags |= SB_I_SKIP_SYNC | SB_I_IMA_UNVERIFIABLE_SIGNATURE;
err = -ENOMEM;
root_dentry = ovl_get_root(sb, upperpath.dentry, oe);
--
2.40.1
