ipv6: drop packets with multiple fragmentation headers

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>

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 850e95bc766c8504d4fbc2c592c1327ef5994431..b8b7dc755752d8cfe6337ca92062b196cd19f073 100644 (file)
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -101,6 +101,7 @@ struct inet6_skb_parm {
 #define IP6SKB_FORWARDED       2
 #define IP6SKB_REROUTED                4
 #define IP6SKB_ROUTERALERT     8
+#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 790d9f4b8b0b21c1d4dd4577ee6a472bd96fd729..1aeb473b2cc695d8d2b0a3696972ec9228455d14 100644 (file)
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -490,6 +490,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
        ipv6_hdr(head)->payload_len = htons(payload_len);
        ipv6_change_dsfield(ipv6_hdr(head), 0xff, ecn);
        IP6CB(head)->nhoff = nhoff;
+       IP6CB(head)->flags |= IP6SKB_FRAGMENTED;
 
        /* Yes, and fold redundant checksum back. 8) */
        if (head->ip_summed == CHECKSUM_COMPLETE)
@@ -524,6 +525,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
        struct net *net = dev_net(skb_dst(skb)->dev);
        int evicted;
 
+       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 */
@@ -544,6 +548,7 @@ 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;
        }