From 2164def67ce8d50a204dfd8bb14d345a8168c127 Mon Sep 17 00:00:00 2001
From: "Andrey V. Elsukov" <ae@FreeBSD.org>
Date: Mon, 29 Jan 2018 11:03:29 +0000
Subject: [PATCH] Do not skip scope zone violation check, when mbuf has
 M_FASTFWD_OURS flag.

When mbuf has M_FASTFWD_OURS flag, this means that a destination address
is our local, but we still need to pass scope zone violation check,
because protocol level expects that IPv6 link-local addresses have
embedded scope zone indexes. This should fix the problem, when ipfw is
used to forward packets to local address and source address of a packet
is IPv6 LLA.

Reported by:	sbruno
MFC after:	3 weeks
---
 sys/netinet6/ip6_input.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/sys/netinet6/ip6_input.c b/sys/netinet6/ip6_input.c
index ec492031c01..bec519de435 100644
--- a/sys/netinet6/ip6_input.c
+++ b/sys/netinet6/ip6_input.c
@@ -573,10 +573,8 @@ ip6_input(struct mbuf *m)
 		/*
 		 * Firewall changed destination to local.
 		 */
-		m->m_flags &= ~M_FASTFWD_OURS;
-		ours = 1;
 		ip6 = mtod(m, struct ip6_hdr *);
-		goto hbhcheck;
+		goto passin;
 	}
 
 	/*
@@ -737,10 +735,8 @@ ip6_input(struct mbuf *m)
 		if ((m = ip6_tryforward(m)) == NULL)
 			return;
 		if (m->m_flags & M_FASTFWD_OURS) {
-			m->m_flags &= ~M_FASTFWD_OURS;
-			ours = 1;
 			ip6 = mtod(m, struct ip6_hdr *);
-			goto hbhcheck;
+			goto passin;
 		}
 	}
 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
@@ -771,13 +767,7 @@ ip6_input(struct mbuf *m)
 		return;
 	ip6 = mtod(m, struct ip6_hdr *);
 	srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
-
-	if (m->m_flags & M_FASTFWD_OURS) {
-		m->m_flags &= ~M_FASTFWD_OURS;
-		ours = 1;
-		goto hbhcheck;
-	}
-	if ((m->m_flags & M_IP6_NEXTHOP) &&
+	if ((m->m_flags & (M_IP6_NEXTHOP | M_FASTFWD_OURS)) == M_IP6_NEXTHOP &&
 	    m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
 		/*
 		 * Directly ship the packet on.  This allows forwarding
@@ -808,6 +798,11 @@ passin:
 		IP6STAT_INC(ip6s_badscope);
 		goto bad;
 	}
+	if (m->m_flags & M_FASTFWD_OURS) {
+		m->m_flags &= ~M_FASTFWD_OURS;
+		ours = 1;
+		goto hbhcheck;
+	}
 	/*
 	 * Multicast check. Assume packet is for us to avoid
 	 * prematurely taking locks.