From cbb9404a50521cdee71346d162b72d3cde270b9e Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Thu, 28 Jan 2021 10:22:48 +0100
Subject: [PATCH] ovl: perform vfs_getxattr() with mounter creds
[ 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 b584dca845ba..4fadafd8bdc1 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -346,7 +346,9 @@ 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;
}