From 4d7caa4ba281e345208cddd64d363f86268bf145 Mon Sep 17 00:00:00 2001
From: bluhm <bluhm@openbsd.org>
Date: Fri, 16 Jun 2023 19:18:56 +0000
Subject: [PATCH] If TSO is enabled, fix the IPv6 forward counters and icmp6
 redirect.

First try to send with TSO.  The goto senderr handles icmp6 redirect
and other errors.  If TSO is not necessary and the interface MTU
fits, just send the packet.  Again goto senderr handles icmp6.
Finally care about icmp6 packet too big.

tested and OK jan@
---
 sys/netinet6/ip6_forward.c | 42 +++++++++++++++++---------------------
 1 file changed, 19 insertions(+), 23 deletions(-)

diff --git a/sys/netinet6/ip6_forward.c b/sys/netinet6/ip6_forward.c
index 85a7e913406..db68b32eca8 100644
--- a/sys/netinet6/ip6_forward.c
+++ b/sys/netinet6/ip6_forward.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_forward.c,v 1.110 2023/06/01 09:05:33 jan Exp $	*/
+/*	$OpenBSD: ip6_forward.c,v 1.111 2023/06/16 19:18:56 bluhm Exp $	*/
 /*	$KAME: ip6_forward.c,v 1.75 2001/06/29 12:42:13 jinmei Exp $	*/
 
 /*
@@ -321,35 +321,30 @@ reroute:
 
 	error = tcp_if_output_tso(ifp, &m, sin6tosa(sin6), rt, IFCAP_TSOv6,
 	    ifp->if_mtu);
+	if (error)
+		ip6stat_inc(ip6s_cantforward);
+	else if (m == NULL)
+		ip6stat_inc(ip6s_forward);
 	if (error || m == NULL)
-		goto freecopy;
+		goto senderr;
 
 	/* Check the size after pf_test to give pf a chance to refragment. */
-	if (m->m_pkthdr.len > ifp->if_mtu) {
-		if (mcopy)
-			icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0,
-			    ifp->if_mtu);
-		m_freem(m);
-		goto out;
+	if (m->m_pkthdr.len <= ifp->if_mtu) {
+		in6_proto_cksum_out(m, ifp);
+		error = ifp->if_output(ifp, m, sin6tosa(sin6), rt);
+		if (error)
+			ip6stat_inc(ip6s_cantforward);
+		else
+			ip6stat_inc(ip6s_forward);
+		goto senderr;
 	}
 
-	in6_proto_cksum_out(m, ifp);
-	error = ifp->if_output(ifp, m, sin6tosa(sin6), rt);
-	if (error) {
-		ip6stat_inc(ip6s_cantforward);
-	} else {
-		ip6stat_inc(ip6s_forward);
-		if (type)
-			ip6stat_inc(ip6s_redirectsent);
-		else {
-			if (mcopy)
-				goto freecopy;
-		}
-	}
+	if (mcopy != NULL)
+		icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, ifp->if_mtu);
+	m_freem(m);
+	goto out;
 
-#if NPF > 0 || defined(IPSEC)
 senderr:
-#endif
 	if (mcopy == NULL)
 		goto out;
 
@@ -357,6 +352,7 @@ senderr:
 	case 0:
 		if (type == ND_REDIRECT) {
 			icmp6_redirect_output(mcopy, rt);
+			ip6stat_inc(ip6s_redirectsent);
 			goto out;
 		}
 		goto freecopy;
-- 
2.20.1