ZFS Security issues with snapshots for (longer term) backups

[jamie]

It's already possible for root to mount a snapshot at any arbitrary directory. All that is needed is an option to set snapshots not to automount under .zfs/

In fact, all we need would be for the following to work:

# zfs snapshot -o canmount=noauto ZFS:0/usr@test
cannot create snapshots : this property can not be modified for snapshots