From: Eric Snowberg eric.snowberg@oracle.com
[ 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@oracle.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 ae1058fbfb5b2..8c60da7b4afd8 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -2052,7 +2052,7 @@ 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);