From 3377413b2b5aaca180b68a20738e0f16f54b3c52 Mon Sep 17 00:00:00 2001
From: jca <jca@openbsd.org>
Date: Tue, 28 Jun 2016 16:59:14 +0000
Subject: [PATCH] Use IPV6_MINHOPCOUNT to finish implementing ttl-security for
 IPv6.

ok renato@ deraadt@
---
 usr.sbin/bgpd/bgpd.conf.5 |  8 ++------
 usr.sbin/bgpd/session.c   | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/usr.sbin/bgpd/bgpd.conf.5 b/usr.sbin/bgpd/bgpd.conf.5
index 3cd14e0d261..09161d6a4fb 100644
--- a/usr.sbin/bgpd/bgpd.conf.5
+++ b/usr.sbin/bgpd/bgpd.conf.5
@@ -1,4 +1,4 @@
-.\" $OpenBSD: bgpd.conf.5,v 1.143 2016/06/11 11:43:02 tobias Exp $
+.\" $OpenBSD: bgpd.conf.5,v 1.144 2016/06/28 16:59:14 jca Exp $
 .\"
 .\" Copyright (c) 2004 Claudio Jeker <claudio@openbsd.org>
 .\" Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -16,7 +16,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: June 11 2016 $
+.Dd $Mdocdate: June 28 2016 $
 .Dt BGPD.CONF 5
 .Os
 .Sh NAME
@@ -972,10 +972,6 @@ incoming packets are required to have a TTL of 256 minus multihop distance,
 ensuring they have not passed through more than the expected number of hops.
 The default is
 .Ic no .
-.Pp
-There is currently only partial support for ttl-security with IPv6:
-the TTL of outgoing packets is set,
-but no check is made for the TTL of incoming packets.
 .El
 .Sh FILTER
 .Xr bgpd 8
diff --git a/usr.sbin/bgpd/session.c b/usr.sbin/bgpd/session.c
index a71339e8da2..545347a546d 100644
--- a/usr.sbin/bgpd/session.c
+++ b/usr.sbin/bgpd/session.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: session.c,v 1.348 2016/06/06 15:59:10 benno Exp $ */
+/*	$OpenBSD: session.c,v 1.349 2016/06/28 16:59:14 jca Exp $ */
 
 /*
  * Copyright (c) 2003, 2004, 2005 Henning Brauer <henning@openbsd.org>
@@ -1201,12 +1201,15 @@ session_setup_socket(struct peer *p)
 			/* set hoplimit to foreign router's distance
 			   1=direct n=multihop with ttlsec, we always use 255 */
 			if (p->conf.ttlsec) {
-			/*
-			 * XXX Kernel has no ip6 equivalent of MINTTL yet so
-			 * we can't check incoming packets, but we can at least
-			 * set the outgoing TTL to allow sessions configured
-			 * with ttl-security to come up.
-			 */
+				ttl = 256 - p->conf.distance;
+				if (setsockopt(p->fd, IPPROTO_IPV6,
+				    IPV6_MINHOPCOUNT, &ttl, sizeof(ttl))
+				    == -1) {
+					log_peer_warn(&p->conf,
+					    "session_setup_socket: "
+					    "setsockopt MINHOPCOUNT");
+					return (-1);
+				}
 				ttl = 255;
 			}
 			if (setsockopt(p->fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS,
-- 
2.20.1