[PATCH 5.4 11/60] ovl: perform vfs_getxattr() with mounter creds

Greg Kroah-Hartman
2021-02-15T16:00:10Z

From: Miklos Szeredi <mszeredi@redhat.com>

[ Upstream commit 554677b97257b0b69378bd74e521edb7e94769ff ]

The vfs_getxattr() in ovl_xattr_set() is used to check whether an xattr
exist on a lower layer file that is to be removed. If the xattr does not
exist, then no need to copy up the file.

This call of vfs_getxattr() wasn't wrapped in credential override, and this
is probably okay. But for consitency wrap this instance as well.

Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/overlayfs/inode.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index bb980721502dd..56b55397a7a00 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -337,7 +337,9 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
goto out;

if (!value && !upperdentry) {
+ old_cred = ovl_override_creds(dentry->d_sb);
err = vfs_getxattr(realdentry, name, NULL, 0);
+ revert_creds(old_cred);
if (err < 0)
goto out_drop_write;
}
--
2.27.0