From d024206133ce21936b3d5780359afc00247655b7 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Wed, 15 Jan 2014 18:15:52 +0100 Subject: [PATCH] btrfs: restrict snapshotting to own subvolumes Currently, any user can snapshot any subvolume if the path is accessible and thus indirectly create and keep files he does not own under his direcotries. This is not possible with traditional directories. In security context, a user can snapshot root filesystem and pin any potentially buggy binaries, even if the updates are applied. All the snapshots are visible to the administrator, so it's possible to verify if there are suspicious snapshots. Another more practical problem is that any user can pin the space used by eg. root and cause ENOSPC. Original report: https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/484786 CC: stable@vger.kernel.org Signed-off-by: David Sterba Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 829999d..8d4457f 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1574,6 +1574,12 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file, btrfs_info(BTRFS_I(src_inode)->root->fs_info, "Snapshot src from another FS"); ret = -EINVAL; + } else if (!inode_owner_or_capable(src_inode)) { + /* + * Subvolume creation is not restricted, but snapshots + * are limited to own subvolumes only + */ + ret = -EPERM; } else { ret = btrfs_mksubvol(&file->f_path, name, namelen, BTRFS_I(src_inode)->root, -- 2.7.4