raw socket+prison warning

For those of you not subscribed to src-committers_at_FreeBSD.org,
cvs-src_at_FreeBSD.org or cvs-all_at_FreeBSD.org, I just committed
a warning note in jail(8) for the security.jail.allow_raw_sockets
sysctl MIB about the risks of enabling raw sockets in prisons.

Because raw sockets can be used to configure and interact
with various network subsystems, extra caution should be
used where privileged access to jails is given out to
untrusted parties. As such, by default this option is disabled.

A few others and I are currently auditing the kernel
source code to ensure that the use of raw sockets by
privledged prison users is safe.

--
Christian S.J. Peron
csjp_at_FreeBSD.org
FreeBSD committer