ipv6: Make icmp route lookup code a bit clearer.

The route lookup code in icmpv6_send() is slightly tricky as a result of
having to handle all of the requirements of RFC 4301 host relookups.

Pull the route resolution into a seperate function, so that the error
handling and route reference counting is hopefully easier to see and
contained wholly within this new routine.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index a31d91b..e332bae 100644 (file)
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -300,6 +300,70 @@ static void mip6_addr_swap(struct sk_buff *skb)
 static inline void mip6_addr_swap(struct sk_buff *skb) {}
 #endif
 
+static struct dst_entry *icmpv6_route_lookup(struct net *net, struct sk_buff *skb,
+                                            struct sock *sk, struct flowi *fl)
+{
+       struct dst_entry *dst, *dst2;
+       struct flowi fl2;
+       int err;
+
+       err = ip6_dst_lookup(sk, &dst, fl);
+       if (err)
+               return ERR_PTR(err);
+
+       /*
+        * We won't send icmp if the destination is known
+        * anycast.
+        */
+       if (((struct rt6_info *)dst)->rt6i_flags & RTF_ANYCAST) {
+               LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: acast source\n");
+               dst_release(dst);
+               return ERR_PTR(-EINVAL);
+       }
+
+       /* No need to clone since we're just using its address. */
+       dst2 = dst;
+
+       err = xfrm_lookup(net, &dst, fl, sk, 0);
+       switch (err) {
+       case 0:
+               if (dst != dst2)
+                       return dst;
+               break;
+       case -EPERM:
+               dst = NULL;
+               break;
+       default:
+               return ERR_PTR(err);
+       }
+
+       err = xfrm_decode_session_reverse(skb, &fl2, AF_INET6);
+       if (err)
+               goto relookup_failed;
+
+       err = ip6_dst_lookup(sk, &dst2, &fl2);
+       if (err)
+               goto relookup_failed;
+
+       err = xfrm_lookup(net, &dst2, &fl2, sk, XFRM_LOOKUP_ICMP);
+       switch (err) {
+       case 0:
+               dst_release(dst);
+               dst = dst2;
+               break;
+       case -EPERM:
+               dst_release(dst);
+               return ERR_PTR(err);
+       default:
+               goto relookup_failed;
+       }
+
+relookup_failed:
+       if (dst)
+               return dst;
+       return ERR_PTR(err);
+}
+
 /*
  *     Send an ICMP message in response to a packet in error
  */
@@ -312,10 +376,8 @@ void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
        struct ipv6_pinfo *np;
        struct in6_addr *saddr = NULL;
        struct dst_entry *dst;
-       struct dst_entry *dst2;
        struct icmp6hdr tmp_hdr;
        struct flowi fl;
-       struct flowi fl2;
        struct icmpv6_msg msg;
        int iif = 0;
        int addr_type = 0;
@@ -408,57 +470,10 @@ void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
        if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
                fl.oif = np->mcast_oif;
 
-       err = ip6_dst_lookup(sk, &dst, &fl);
-       if (err)
-               goto out;
-
-       /*
-        * We won't send icmp if the destination is known
-        * anycast.
-        */
-       if (((struct rt6_info *)dst)->rt6i_flags & RTF_ANYCAST) {
-               LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: acast source\n");
-               goto out_dst_release;
-       }
-
-       /* No need to clone since we're just using its address. */
-       dst2 = dst;
-
-       err = xfrm_lookup(net, &dst, &fl, sk, 0);
-       switch (err) {
-       case 0:
-               if (dst != dst2)
-                       goto route_done;
-               break;
-       case -EPERM:
-               dst = NULL;
-               break;
-       default:
+       dst = icmpv6_route_lookup(net, skb, sk, &fl);
+       if (IS_ERR(dst))
                goto out;
-       }
-
-       if (xfrm_decode_session_reverse(skb, &fl2, AF_INET6))
-               goto relookup_failed;
-
-       if (ip6_dst_lookup(sk, &dst2, &fl2))
-               goto relookup_failed;
-
-       err = xfrm_lookup(net, &dst2, &fl2, sk, XFRM_LOOKUP_ICMP);
-       switch (err) {
-       case 0:
-               dst_release(dst);
-               dst = dst2;
-               break;
-       case -EPERM:
-               goto out_dst_release;
-       default:
-relookup_failed:
-               if (!dst)
-                       goto out;
-               break;
-       }
 
-route_done:
        if (ipv6_addr_is_multicast(&fl.fl6_dst))
                hlimit = np->mcast_hops;
        else