[NETFILTER]: Fix ipv6 TCP/UDP matching wrt. extension headers

net/ipv6/ipv6_syms.c

@@ -46,3 +46,4 @@ EXPORT_SYMBOL(ip6_append_data);
 EXPORT_SYMBOL(ip6_flush_pending_frames);
 EXPORT_SYMBOL(ip6_push_pending_frames);
 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
+EXPORT_SYMBOL(ipv6_skip_exthdr);

net/ipv6/netfilter/ip6_tables.c

@@ -1570,8 +1570,10 @@ tcp_match(const struct sk_buff *skb,
 	  u_int16_t datalen,
 	  int *hotdrop)
 {
-	const struct tcphdr *tcp = hdr;
+	const struct tcphdr *tcp;
 	const struct ip6t_tcp *tcpinfo = matchinfo;
+	int tcpoff;
+	u8 nexthdr = skb->nh.ipv6h->nexthdr;
 
 	/* To quote Alan:
 
@@ -1592,6 +1594,24 @@ tcp_match(const struct sk_buff *skb,
 		return 0;
 	}
 
+	tcpoff = (u8*)(skb->nh.ipv6h + 1) - skb->data;
+	tcpoff = ipv6_skip_exthdr(skb, tcpoff, &nexthdr, skb->len - tcpoff);
+	if (tcpoff < 0 || tcpoff > skb->len) {
+		duprintf("tcp_match: cannot skip exthdr. Dropping.\n");
+		*hotdrop = 1;
+		return 0;
+	} else if (nexthdr == IPPROTO_FRAGMENT)
+		return 0;
+	else if (nexthdr != IPPROTO_TCP ||
+		 skb->len - tcpoff < sizeof(struct tcphdr)) {
+		/* cannot be occured */
+		duprintf("tcp_match: cannot get TCP header. Dropping.\n");
+		*hotdrop = 1;
+		return 0;
+	}
+
+	tcp = (struct tcphdr *)(skb->data + tcpoff);
+
 	/* FIXME: Try tcp doff >> packet len against various stacks --RR */
 
 #define FWINVTCP(bool,invflg) ((bool) ^ !!(tcpinfo->invflags & invflg))
@@ -1642,8 +1662,10 @@ udp_match(const struct sk_buff *skb,
 	  u_int16_t datalen,
 	  int *hotdrop)
 {
-	const struct udphdr *udp = hdr;
+	const struct udphdr *udp;
 	const struct ip6t_udp *udpinfo = matchinfo;
+	int udpoff;
+	u8 nexthdr = skb->nh.ipv6h->nexthdr;
 
 	if (offset == 0 && datalen < sizeof(struct udphdr)) {
 		/* We've been asked to examine this packet, and we
@@ -1653,6 +1675,23 @@ udp_match(const struct sk_buff *skb,
 		return 0;
 	}
 
+	udpoff = (u8*)(skb->nh.ipv6h + 1) - skb->data;
+	udpoff = ipv6_skip_exthdr(skb, udpoff, &nexthdr, skb->len - udpoff);
+	if (udpoff < 0 || udpoff > skb->len) {
+		duprintf("udp_match: cannot skip exthdr. Dropping.\n");
+		*hotdrop = 1;
+		return 0;
+	} else if (nexthdr == IPPROTO_FRAGMENT)
+		return 0;
+	else if (nexthdr != IPPROTO_UDP ||
+		 skb->len - udpoff < sizeof(struct udphdr)) {
+		duprintf("udp_match: cannot get UDP header. Dropping.\n");
+		*hotdrop = 1;
+		return 0;
+	}
+
+	udp = (struct udphdr *)(skb->data + udpoff);
+
 	/* Must not be a fragment. */
 	return !offset
 		&& port_match(udpinfo->spts[0], udpinfo->spts[1],