Re: mount_nullfs inside a jail

On Mon, 23 Jul 2007 15:33:33 +0200 Pawel Jakub Dawidek wrote:
On Sun, Jul 22, 2007 at 04:18:06AM +0400, Boris Samorodov wrote:

Is it possible to use mount_nullfs inside a jail?

With amd64-current:
# sysctl security.jail
security.jail.jailed: 1
security.jail.mount_allowed: 1
security.jail.chflags_allowed: 1
security.jail.allow_raw_sockets: 0
security.jail.enforce_statfs: 2
security.jail.sysvipc_allowed: 1
security.jail.socket_unixiproute_only: 1
security.jail.set_hostname_allowed: 1
# mount_nullfs /usr/ports /mnt
mount_nullfs: Operation not permitted

It is not possible. From jail(8):

This MIB entry determines if a privileged user inside a jail will be
able to mount and unmount file system types marked as jail-friendly.
The lsvfs(1) command can be used to find file system types available
for mount from within a jail. This functionality is disabled by
default, but can be enabled by setting this MIB entry to 1.

# lsvfs
Filesystem Refs Flags
-------------------------------- ----- ---------------
zfs 0 jail
nullfs 0 loopback

Thanks, Pavel. Somehow I failed to do RTFM.

As you can see, nullfs doesn't have 'jail' flag. The only jail-friendly
file system currently is ZFS. Nullfs is a good candidate for a
jail-friendly file system, but is not marked as such yet.

Does somebody know if only a flag is missing or not?

Boris Samorodov (bsam)
Research Engineer, Telephone & Internet SP
FreeBSD committer, The Power To Serve
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