[ 069/143] ipv6: drop packets with multiple fragmentation headers

Willy Tarreau
2014-05-12T01:43:36Z

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

[ 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@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
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 c662efa..5bf3324 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -248,6 +248,7 @@ struct inet6_skb_parm {

#define IP6SKB_XFRM_TRANSFORMED 1
#define IP6SKB_FORWARDED 2
+#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 105de22..0c09d8e 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -503,6 +503,7 @@ 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)
@@ -537,6 +538,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
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 */
@@ -557,6 +561,7 @@ 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;
}

--
1.7.12.2.21.g234cd45.dirty