From 100c1c44df3cd909c8b593d49b33038001210b40 Mon Sep 17 00:00:00 2001
From: Hasso Tepper <hasso@dragonflybsd.org>
Date: Fri, 3 Oct 2008 07:59:20 +0000
Subject: [PATCH] If a neighbor solictation or neighbor advertisement isn't
 from the unspecified address, make sure that the source address matches one
 of the interfaces address prefixes.

CVE-2008-2476

Obtained-from: NetBSD with modifications
---
 sys/netinet6/in6.c     | 30 +++++++++++++++++++++++++++++-
 sys/netinet6/in6_var.h |  4 +++-
 sys/netinet6/nd6_nbr.c | 22 +++++++++++++++++++---
 3 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index c29085b845..71316a30db 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -1,5 +1,5 @@
 /*	$FreeBSD: src/sys/netinet6/in6.c,v 1.7.2.9 2002/04/28 05:40:26 suz Exp $	*/
-/*	$DragonFly: src/sys/netinet6/in6.c,v 1.29 2008/04/20 13:44:26 swildner Exp $	*/
+/*	$DragonFly: src/sys/netinet6/in6.c,v 1.30 2008/10/03 07:59:20 hasso Exp $	*/
 /*	$KAME: in6.c,v 1.259 2002/01/21 11:37:50 keiichi Exp $	*/
 
 /*
@@ -1783,6 +1783,34 @@ in6ifa_ifpwithaddr(struct ifnet *ifp, struct in6_addr *addr)
 		return (NULL);
 }
 
+/*
+ * find the internet address on a given interface corresponding to a neighbor's
+ * address.
+ */
+struct in6_ifaddr *
+in6ifa_ifplocaladdr(const struct ifnet *ifp, const struct in6_addr *addr)
+{
+	struct ifaddr *ifa;
+	struct in6_ifaddr *ia;
+	struct ifaddr_container *ifac;
+
+	TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
+		ifa = ifac->ifa;
+
+		if (ifa->ifa_addr == NULL)
+			continue;	/* just for safety */
+		if (ifa->ifa_addr->sa_family != AF_INET6)
+			continue;
+		ia = (struct in6_ifaddr *)ifa;
+		if (IN6_ARE_MASKED_ADDR_EQUAL(addr,
+				&ia->ia_addr.sin6_addr,
+				&ia->ia_prefixmask.sin6_addr))
+			return ia;
+	}
+
+	return NULL;
+}
+
 /*
  * Convert IP6 address to printable (loggable) representation.
  */
diff --git a/sys/netinet6/in6_var.h b/sys/netinet6/in6_var.h
index ee47cf8c1a..68ca18d33c 100644
--- a/sys/netinet6/in6_var.h
+++ b/sys/netinet6/in6_var.h
@@ -1,5 +1,5 @@
 /*	$FreeBSD: src/sys/netinet6/in6_var.h,v 1.3.2.3 2002/04/28 05:40:27 suz Exp $	*/
-/*	$DragonFly: src/sys/netinet6/in6_var.h,v 1.9 2008/03/07 11:34:21 sephe Exp $	*/
+/*	$DragonFly: src/sys/netinet6/in6_var.h,v 1.10 2008/10/03 07:59:20 hasso Exp $	*/
 /*	$KAME: in6_var.h,v 1.56 2001/03/29 05:34:31 itojun Exp $	*/
 
 /*
@@ -607,6 +607,8 @@ void	in6_purgemkludge (struct ifnet *);
 struct in6_ifaddr *in6ifa_ifpforlinklocal (struct ifnet *, int);
 struct in6_ifaddr *in6ifa_ifpwithaddr (struct ifnet *,
 					     struct in6_addr *);
+struct in6_ifaddr *in6ifa_ifplocaladdr(const struct ifnet *,
+					const struct in6_addr *);
 char	*ip6_sprintf (const struct in6_addr *);
 int	in6_addr2scopeid (struct ifnet *, struct in6_addr *);
 int	in6_matchlen (struct in6_addr *, struct in6_addr *);
diff --git a/sys/netinet6/nd6_nbr.c b/sys/netinet6/nd6_nbr.c
index 5aff021ce7..2c4a8e301b 100644
--- a/sys/netinet6/nd6_nbr.c
+++ b/sys/netinet6/nd6_nbr.c
@@ -1,5 +1,5 @@
 /*	$FreeBSD: src/sys/netinet6/nd6_nbr.c,v 1.4.2.6 2003/01/23 21:06:47 sam Exp $	*/
-/*	$DragonFly: src/sys/netinet6/nd6_nbr.c,v 1.23 2008/03/07 11:34:21 sephe Exp $	*/
+/*	$DragonFly: src/sys/netinet6/nd6_nbr.c,v 1.24 2008/10/03 07:59:20 hasso Exp $	*/
 /*	$KAME: nd6_nbr.c,v 1.86 2002/01/21 02:33:04 jinmei Exp $	*/
 
 /*
@@ -149,6 +149,15 @@ nd6_ns_input(struct mbuf *m, int off, int icmp6len)
 				"(wrong ip6 dst)\n"));
 			goto bad;
 		}
+	} else {
+		/*
+		 * Make sure the source address is from a neighbor's address.
+		 */
+		if (in6ifa_ifplocaladdr(ifp, &saddr6) == NULL) {
+			nd6log((LOG_INFO, "nd6_ns_input: "
+			    "NS packet from non-neighbor\n"));
+			goto bad;
+		}
 	}
 
 	if (IN6_IS_ADDR_MULTICAST(&taddr6)) {
@@ -532,9 +541,7 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 	struct ifnet *ifp = m->m_pkthdr.rcvif;
 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 	struct nd_neighbor_advert *nd_na;
-#if 0
 	struct in6_addr saddr6 = ip6->ip6_src;
-#endif
 	struct in6_addr daddr6 = ip6->ip6_dst;
 	struct in6_addr taddr6;
 	int flags;
@@ -628,6 +635,15 @@ nd6_na_input(struct mbuf *m, int off, int icmp6len)
 		goto freeit;
 	}
 
+	/*
+	 * Make sure the source address is from a neighbor's address.
+	 */
+	if (in6ifa_ifplocaladdr(ifp, &saddr6) == NULL) {
+		nd6log((LOG_INFO, "nd6_na_input: "
+		    "NA packet from non-neighbor\n"));
+		goto bad;
+	}
+
 	if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
 		nd6log((LOG_INFO,
 		    "nd6_na_input: lladdrlen mismatch for %s "
-- 
2.41.0