From 9efb069de4ba748d284f6129e71de239f801053a Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 28 Jan 2021 10:22:48 +0100 Subject: [PATCH] ovl: add warning on user_ns mismatch Currently there's no way to create an overlay filesystem outside of the current user namespace. Make sure that if this assumption changes it doesn't go unnoticed. Reported-by: "Eric W. Biederman" Signed-off-by: Miklos Szeredi --- fs/overlayfs/super.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 2bd570c..82cd6d5 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1923,6 +1923,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) unsigned int numlower; int err; + err = -EIO; + if (WARN_ON(sb->s_user_ns != current_user_ns())) + goto out; + sb->s_d_op = &ovl_dentry_operations; err = -ENOMEM; -- 2.7.4