ipv6: distinguish frag queues by device for multicast and link-local packets

commit 264640fc upstream.

If a fragmented multicast packet is received on an ethernet device which
has an active macvlan on top of it, each fragment is duplicated and
received both on the underlying device and the macvlan. If some
fragments for macvlan are processed before the whole packet for the
underlying device is reassembled, the "overlapping fragments" test in
ip6_frag_queue() discards the whole fragment queue.

To resolve this, add device ifindex to the search key and require it to
match reassembling multicast packets and packets to link-local
addresses.

Note: similar patch has been already submitted by Yoshifuji Hideaki in

  http://patchwork.ozlabs.org/patch/220979/

but got lost and forgotten for some reason.
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

include/net/ipv6.h

@@ -492,6 +492,7 @@ struct ip6_create_arg {
 	u32 user;
 	const struct in6_addr *src;
 	const struct in6_addr *dst;
+	int iif;
 	u8 ecn;
 };
 

net/ipv6/netfilter/nf_conntrack_reasm.c

@@ -184,7 +184,7 @@ static void nf_ct_frag6_expire(unsigned long data)
 /* Creation primitives. */
 static inline struct frag_queue *fq_find(struct net *net, __be32 id,
 					 u32 user, struct in6_addr *src,
-					 struct in6_addr *dst, u8 ecn)
+					 struct in6_addr *dst, int iif, u8 ecn)
 {
 	struct inet_frag_queue *q;
 	struct ip6_create_arg arg;
@@ -194,6 +194,7 @@ static inline struct frag_queue *fq_find(struct net *net, __be32 id,
 	arg.user = user;
 	arg.src = src;
 	arg.dst = dst;
+	arg.iif = iif;
 	arg.ecn = ecn;
 
 	read_lock_bh(&nf_frags.lock);
@@ -602,7 +603,7 @@ struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb, u32 user)
 	local_bh_enable();
 
 	fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr,
-		     ip6_frag_ecn(hdr));
+		     skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr));
 	if (fq == NULL) {
 		pr_debug("Can't find and can't create new queue\n");
 		goto ret_orig;

net/ipv6/reassembly.c

@@ -111,7 +111,10 @@ bool ip6_frag_match(struct inet_frag_queue *q, void *a)
 	return	fq->id == arg->id &&
 		fq->user == arg->user &&
 		ipv6_addr_equal(&fq->saddr, arg->src) &&
-		ipv6_addr_equal(&fq->daddr, arg->dst);
+		ipv6_addr_equal(&fq->daddr, arg->dst) &&
+		(arg->iif == fq->iif ||
+		 !(ipv6_addr_type(arg->dst) & (IPV6_ADDR_MULTICAST |
+					       IPV6_ADDR_LINKLOCAL)));
 }
 EXPORT_SYMBOL(ip6_frag_match);
 
@@ -180,7 +183,7 @@ static void ip6_frag_expire(unsigned long data)
 
 static __inline__ struct frag_queue *
 fq_find(struct net *net, __be32 id, const struct in6_addr *src,
-	const struct in6_addr *dst, u8 ecn)
+	const struct in6_addr *dst, int iif, u8 ecn)
 {
 	struct inet_frag_queue *q;
 	struct ip6_create_arg arg;
@@ -190,6 +193,7 @@ fq_find(struct net *net, __be32 id, const struct in6_addr *src,
 	arg.user = IP6_DEFRAG_LOCAL_DELIVER;
 	arg.src = src;
 	arg.dst = dst;
+	arg.iif = iif;
 	arg.ecn = ecn;
 
 	read_lock(&ip6_frags.lock);
@@ -558,7 +562,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 				 IPSTATS_MIB_REASMFAILS, evicted);
 
 	fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr,
-		     ip6_frag_ecn(hdr));
+		     skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr));
 	if (fq != NULL) {
 		int ret;