From 01e2145cca23fb4844c03db195dde8263846b9d4 Mon Sep 17 00:00:00 2001
From: dlg <dlg@openbsd.org>
Date: Mon, 19 Feb 2018 00:23:57 +0000
Subject: [PATCH] add support for setting and displaying whether a tunnel
 allows fragmentation

ifconfig will output "nodf" or "df" on tunnel interfaces that support
the ioctl., and accepts "tunneldf" and "-tunneldf" as options to
try and configure it.
---
 sbin/ifconfig/ifconfig.8 |  9 +++++++--
 sbin/ifconfig/ifconfig.c | 28 +++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/sbin/ifconfig/ifconfig.8 b/sbin/ifconfig/ifconfig.8
index 68f24911b85..42990ad0dd9 100644
--- a/sbin/ifconfig/ifconfig.8
+++ b/sbin/ifconfig/ifconfig.8
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ifconfig.8,v 1.299 2018/02/15 04:21:46 dlg Exp $
+.\"	$OpenBSD: ifconfig.8,v 1.300 2018/02/19 00:23:57 dlg Exp $
 .\"	$NetBSD: ifconfig.8,v 1.11 1996/01/04 21:27:29 pk Exp $
 .\"     $FreeBSD: ifconfig.8,v 1.16 1998/02/01 07:03:29 steve Exp $
 .\"
@@ -31,7 +31,7 @@
 .\"
 .\"     @(#)ifconfig.8	8.4 (Berkeley) 6/1/94
 .\"
-.Dd $Mdocdate: February 15 2018 $
+.Dd $Mdocdate: February 19 2018 $
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -1603,6 +1603,7 @@ for a complete list of the available protocols.
 .Op Oo Fl Oc Ns Cm keepalive Ar period count
 .Op Oo Fl Oc Ns Cm tunnel Ar src_address dest_address
 .Op Cm tunneldomain Ar tableid
+.Op Oo Fl Oc Ns Cm tunneldf
 .Op Cm tunnelttl Ar ttl
 .Op Oo Fl Oc Ns Cm vnetid Ar network-id
 .Ek
@@ -1654,6 +1655,10 @@ interface itself.
 .Ar tableid
 can be set to any valid routing table ID;
 the corresponding routing domain is derived from this table.
+.It Cm tunneldf
+Do not allow fragmentation of encapsulated packets.
+.It Cm -tunneldf
+Allow fragmentation of the encapsulated packets. 
 .It Cm tunnelttl Ar ttl
 Set the IP or multicast TTL of the tunnel packets.
 If supported by the tunnel protocol,
diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c
index ac5705b2651..88956f0d7ff 100644
--- a/sbin/ifconfig/ifconfig.c
+++ b/sbin/ifconfig/ifconfig.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ifconfig.c,v 1.357 2018/02/10 05:55:26 florian Exp $	*/
+/*	$OpenBSD: ifconfig.c,v 1.358 2018/02/19 00:23:57 dlg Exp $	*/
 /*	$NetBSD: ifconfig.c,v 1.40 1997/10/01 02:19:43 enami Exp $	*/
 
 /*
@@ -252,6 +252,8 @@ void	setpfsync_syncpeer(const char *, int);
 void	unsetpfsync_syncpeer(const char *, int);
 void	setpfsync_defer(const char *, int);
 void	pfsync_status(void);
+void	settunneldf(const char *, int);
+void	settunnelnodf(const char *, int);
 void	setpppoe_dev(const char *,int);
 void	setpppoe_svc(const char *,int);
 void	setpppoe_ac(const char *,int);
@@ -434,6 +436,8 @@ const struct	cmd {
 	{ "deletetunnel",  0,		0,		deletetunnel },
 	{ "tunneldomain", NEXTARG,	0,		settunnelinst },
 	{ "tunnelttl",	NEXTARG,	0,		settunnelttl },
+	{ "tunneldf",	0,		0,		settunneldf },
+	{ "-tunneldf",	0,		0,		settunnelnodf },
 	{ "pppoedev",	NEXTARG,	0,		setpppoe_dev },
 	{ "pppoesvc",	NEXTARG,	0,		setpppoe_svc },
 	{ "-pppoesvc",	1,		0,		setpppoe_svc },
@@ -2750,6 +2754,10 @@ phys_status(int force)
 		else if (ifr.ifr_ttl > 0)
 			printf(" ttl %d", ifr.ifr_ttl);
 	}
+
+	if (ioctl(s, SIOCGLIFPHYDF, (caddr_t)&ifr) == 0)
+		printf(" %s", ifr.ifr_df ? "df" : "nodf");
+
 #ifndef SMALL
 	if (ioctl(s, SIOCGLIFPHYRTABLE, (caddr_t)&ifr) == 0 &&
 	    (rdomainid != 0 || ifr.ifr_rdomainid != 0))
@@ -3285,6 +3293,24 @@ settunnelttl(const char *id, int param)
 		warn("SIOCSLIFPHYTTL");
 }
 
+void
+settunneldf(const char *ignored, int alsoignored)
+{
+	strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
+	ifr.ifr_df = 1;
+	if (ioctl(s, SIOCSLIFPHYDF, (caddr_t)&ifr) < 0)
+		warn("SIOCSLIFPHYDF");
+}
+
+void
+settunnelnodf(const char *ignored, int alsoignored)
+{
+	strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
+	ifr.ifr_df = 0;
+	if (ioctl(s, SIOCSLIFPHYDF, (caddr_t)&ifr) < 0)
+		warn("SIOCSLIFPHYDF");
+}
+
 void
 mpe_status(void)
 {
-- 
2.20.1