From 0f16ff0f545d5ec90bbd548afd2983785b546780 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:46 +0100 Subject: [PATCH] ecryptfs: do not mount on top of idmapped mounts Prevent ecryptfs from being mounted on top of idmapped mounts. Stacking filesystems need to be prevented from being mounted on top of idmapped mounts until they have have been converted to handle this. Link: https://lore.kernel.org/r/20210121131959.646623-28-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: James Morris Signed-off-by: Christian Brauner --- fs/ecryptfs/main.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c index e63259f..cdf40a5 100644 --- a/fs/ecryptfs/main.c +++ b/fs/ecryptfs/main.c @@ -531,6 +531,12 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags goto out_free; } + if (mnt_user_ns(path.mnt) != &init_user_ns) { + rc = -EINVAL; + printk(KERN_ERR "Mounting on idmapped mounts currently disallowed\n"); + goto out_free; + } + if (check_ruid && !uid_eq(d_inode(path.dentry)->i_uid, current_uid())) { rc = -EPERM; printk(KERN_ERR "Mount of device (uid: %d) not owned by " -- 2.7.4