ipv6: unify conntrack reassembly expire code with standard one

Two years ago, Shan Wei tried to fix this:
http://patchwork.ozlabs.org/patch/43905/

The problem is that RFC2460 requires an ICMP Time
Exceeded -- Fragment Reassembly Time Exceeded message should be
sent to the source of that fragment, if the defragmentation
times out.

"
   If insufficient fragments are received to complete reassembly of a
   packet within 60 seconds of the reception of the first-arriving
   fragment of that packet, reassembly of that packet must be
   abandoned and all the fragments that have been received for that
   packet must be discarded.  If the first fragment (i.e., the one
   with a Fragment Offset of zero) has been received, an ICMP Time
   Exceeded -- Fragment Reassembly Time Exceeded message should be
   sent to the source of that fragment.
"

As Herbert suggested, we could actually use the standard IPv6
reassembly code which follows RFC2460.

With this patch applied, I can see ICMP Time Exceeded sent
from the receiver when the sender sent out 3/4 fragmented
IPv6 UDP packet.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michal Kubeček <mkubecek@suse.cz>
Cc: David Miller <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: netfilter-devel@vger.kernel.org
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 9bed5d483405..81d4455f6e14 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -411,6 +411,25 @@ struct ip6_create_arg {
 void ip6_frag_init(struct inet_frag_queue *q, void *a);
 bool ip6_frag_match(struct inet_frag_queue *q, void *a);
 
+/*
+ *      Equivalent of ipv4 struct ip
+ */
+struct frag_queue {
+        struct inet_frag_queue  q;
+
+        __be32                  id;             /* fragment id          */
+        u32                     user;
+        struct in6_addr         saddr;
+        struct in6_addr         daddr;
+
+        int                     iif;
+        unsigned int            csum;
+        __u16                   nhoffset;
+};
+
+void ip6_expire_frag_queue(struct net *net, struct frag_queue *fq,
+                           struct inet_frags *frags);
+
 static inline bool ipv6_addr_any(const struct in6_addr *a)
 {
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64