From: dlg <dlg@openbsd.org>
Date: Sun, 11 Feb 2018 00:24:13 +0000 (+0000)
Subject: add an ipv6 "don't fragment" flag to mbufs for ip6_output to use.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=45ad364f7d01c9de832747f18d3161506cc558ea;p=openbsd

add an ipv6 "don't fragment" flag to mbufs for ip6_output to use.

if you need to send an ipv6 packet with ip6_send(), there's no DF
bit in an ipv6 packet and no way to pass the ip6 options to ip6_output
to tell it to not allow fragmentation. this adds an M_IPV6_DF_OUT
"checksum" flag so something creating ipv6 packets a long way from
ip6_output can easily tell it to not allow fragmentation.

grumbling and ok claudio@
---

diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index 03fc4fae449..4818d7cb441 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_output.c,v 1.232 2017/09/01 15:05:31 mpi Exp $	*/
+/*	$OpenBSD: ip6_output.c,v 1.233 2018/02/11 00:24:13 dlg Exp $	*/
 /*	$KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $	*/
 
 /*
@@ -656,7 +656,10 @@ reroute:
 	 */
 	tlen = m->m_pkthdr.len;
 
-	if (opt && (opt->ip6po_flags & IP6PO_DONTFRAG))
+	if (ISSET(m->m_pkthdr.csum_flags, M_IPV6_DF_OUT)) {
+		CLR(m->m_pkthdr.csum_flags, M_IPV6_DF_OUT);
+		dontfrag = 1;
+	} else if (opt && ISSET(opt->ip6po_flags, IP6PO_DONTFRAG))
 		dontfrag = 1;
 	else
 		dontfrag = 0;
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 825cc801843..14a43b44585 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mbuf.h,v 1.234 2018/02/09 02:26:33 patrick Exp $	*/
+/*	$OpenBSD: mbuf.h,v 1.235 2018/02/11 00:24:13 dlg Exp $	*/
 /*	$NetBSD: mbuf.h,v 1.19 1996/02/09 18:25:14 christos Exp $	*/
 
 /*
@@ -224,12 +224,14 @@ struct mbuf {
 #define	M_ICMP_CSUM_OUT		0x0200	/* ICMP/ICMPv6 checksum needed */
 #define	M_ICMP_CSUM_IN_OK	0x0400	/* ICMP/ICMPv6 checksum verified */
 #define	M_ICMP_CSUM_IN_BAD	0x0800	/* ICMP/ICMPv6 checksum bad */
+#define	M_IPV6_DF_OUT		0x1000	/* don't fragment outgoing IPv6 */
 
 #ifdef _KERNEL
 #define MCS_BITS \
     ("\20\1IPV4_CSUM_OUT\2TCP_CSUM_OUT\3UDP_CSUM_OUT\4IPV4_CSUM_IN_OK" \
     "\5IPV4_CSUM_IN_BAD\6TCP_CSUM_IN_OK\7TCP_CSUM_IN_BAD\10UDP_CSUM_IN_OK" \
-    "\11UDP_CSUM_IN_BAD\12ICMP_CSUM_OUT\13ICMP_CSUM_IN_OK\14ICMP_CSUM_IN_BAD")
+    "\11UDP_CSUM_IN_BAD\12ICMP_CSUM_OUT\13ICMP_CSUM_IN_OK\14ICMP_CSUM_IN_BAD" \
+    "\15IPV6_NODF_OUT")
 #endif
 
 /* mbuf types */