[PATCH 3.2 010/149] ipv6: drop packets with multiplefragmentation headers

[Ben Hutchings]

3.2.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit f46078cfcd77fa5165bf849f5e568a7ac5fa569c ]

It is not allowed for an ipv6 packet to contain multiple fragmentation
headers. So discard packets which were already reassembled by
fragmentation logic and send back a parameter problem icmp.

The updates for RFC 6980 will come in later, I have to do a bit more
research here.

Cc: YOSHIFUJI Hideaki <yoshfuji@xxxxxxxxxxxxxx>
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 include/linux/ipv6.h  | 1 +
 net/ipv6/reassembly.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 0c99776..84b1447 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -255,6 +255,7 @@ struct inet6_skb_parm {
 #define IP6SKB_XFRM_TRANSFORMED	1
 #define IP6SKB_FORWARDED	2
 #define IP6SKB_REROUTED		4
+#define IP6SKB_FRAGMENTED      16
 };
 
 #define IP6CB(skb)	((struct inet6_skb_parm*)((skb)->cb))
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 411fe2c..eba5deb 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -517,6 +517,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 	head->tstamp = fq->q.stamp;
 	ipv6_hdr(head)->payload_len = htons(payload_len);
 	IP6CB(head)->nhoff = nhoff;
+	IP6CB(head)->flags |= IP6SKB_FRAGMENTED;
 
 	/* Yes, and fold redundant checksum back. 8) */
 	if (head->ip_summed == CHECKSUM_COMPLETE)
@@ -552,6 +553,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 	const struct ipv6hdr *hdr = ipv6_hdr(skb);
 	struct net *net = dev_net(skb_dst(skb)->dev);
 
+	if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED)
+		goto fail_hdr;
+
 	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
 
 	/* Jumbo payload inhibits frag. header */
@@ -572,6 +576,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 				 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
 
 		IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
+		IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
 		return 1;
 	}
 

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