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authorDavid Sterba <dsterba@suse.cz>2014-01-15 18:15:52 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-06 11:08:18 -0800
commitf0cea52a481c749ac0ed4cf0fd8a00f90306ebd5 (patch)
tree832d5358309b32243224197980889b42620b92b1
parent5c61a3d3ff81ddb53006bbc84aca8363b4f2841b (diff)
downloadlinaro-lsk-f0cea52a481c749ac0ed4cf0fd8a00f90306ebd5.tar.gz
btrfs: restrict snapshotting to own subvolumes
commit d024206133ce21936b3d5780359afc00247655b7 upstream. 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 Signed-off-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/btrfs/ioctl.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 145b2c75ab8..783906c687b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1528,6 +1528,12 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
printk(KERN_INFO "btrfs: Snapshot src from "
"another FS\n");
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,