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, 44 deletions

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 4ff9af628e72..0ee553354ed5 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -65,24 +65,6 @@ struct ip6frag_skb_cb
 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
 
 
-/*
- *      Equivalent of ipv4 struct ipq
- */
-
-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;
-};
-
 static struct inet_frags ip6_frags;
 
 int ip6_frag_nqueues(struct net *net)
@@ -159,21 +141,6 @@ void ip6_frag_init(struct inet_frag_queue *q, void *a)
 }
 EXPORT_SYMBOL(ip6_frag_init);
 
-/* Destruction primitives. */
-
-static __inline__ void fq_put(struct frag_queue *fq)
-{
-        inet_frag_put(&fq->q, &ip6_frags);
-}
-
-/* Kill fq entry. It is not destroyed immediately,
- * because caller (and someone more) holds reference count.
- */
-static __inline__ void fq_kill(struct frag_queue *fq)
-{
-        inet_frag_kill(&fq->q, &ip6_frags);
-}
-
 static void ip6_evictor(struct net *net, struct inet6_dev *idev)
 {
         int evicted;
@@ -183,22 +150,18 @@ static void ip6_evictor(struct net *net, struct inet6_dev *idev)
                 IP6_ADD_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS, evicted);
 }
 
-static void ip6_frag_expire(unsigned long data)
+void ip6_expire_frag_queue(struct net *net, struct frag_queue *fq,
+                           struct inet_frags *frags)
 {
-        struct frag_queue *fq;
         struct net_device *dev = NULL;
-        struct net *net;
-
-        fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
 
         spin_lock(&fq->q.lock);
 
         if (fq->q.last_in & INET_FRAG_COMPLETE)
                 goto out;
 
-        fq_kill(fq);
+        inet_frag_kill(&fq->q, frags);
 
-        net = container_of(fq->q.net, struct net, ipv6.frags);
         rcu_read_lock();
         dev = dev_get_by_index_rcu(net, fq->iif);
         if (!dev)
@@ -222,7 +185,19 @@ out_rcu_unlock:
         rcu_read_unlock();
 out:
         spin_unlock(&fq->q.lock);
-        fq_put(fq);
+        inet_frag_put(&fq->q, frags);
+}
+EXPORT_SYMBOL(ip6_expire_frag_queue);
+
+static void ip6_frag_expire(unsigned long data)
+{
+        struct frag_queue *fq;
+        struct net *net;
+
+        fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
+        net = container_of(fq->q.net, struct net, ipv6.frags);
+
+        ip6_expire_frag_queue(net, fq, &ip6_frags);
 }
 
 static __inline__ struct frag_queue *
@@ -391,7 +366,7 @@ found:
         return -1;
 
 discard_fq:
-        fq_kill(fq);
+        inet_frag_kill(&fq->q, &ip6_frags);
 err:
         IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
                       IPSTATS_MIB_REASMFAILS);
@@ -417,7 +392,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
         unsigned int nhoff;
         int sum_truesize;
 
-        fq_kill(fq);
+        inet_frag_kill(&fq->q, &ip6_frags);
 
         /* Make the one we just received the head. */
         if (prev) {
@@ -586,7 +561,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
                 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 
                 spin_unlock(&fq->q.lock);
-                fq_put(fq);
+                inet_frag_put(&fq->q, &ip6_frags);
                 return ret;
         }