Import a fix for and old security issue (CVE-2010-3830) in pf which
was not relevant to FreeBSD as only root could open /dev/pf by default.
With VIMAGE this is will longer be the case. As pf(4) starts to
be supported with VNETs 3rd party users may open /dev/pf inside the
virtual jail instance; thus we need to address this issue after all.
While OpenBSD largely rewrote code parts for the fix [1], and it's
unclear what Apple [3] did, import the minimal fix from NetBSD [2].

[1] http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/net/pf_ioctl.c.diff?r1=1.235&r2=1.236
[2] http://mail-index.netbsd.org/source-changes/2011/01/19/msg017518.html
[3] https://support.apple.com/en-gb/HT202154

Obtained from: http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/dist/pf/net/pf_ioctl.c.diff?r1=1.42&r2=1.43&only_with_tag=MAIN
MFC After: 2 weeks
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Security: CVE-2010-3830