net: ip, ipv6: handle gso skbs in forwarding path

[pandora-kernel.git] / net / ipv4 / ip_forward.c

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index e9f1217..f3869c1 100644 (file)
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -39,6 +39,71 @@
 #include <net/route.h>
 #include <net/xfrm.h>
 
+static bool ip_may_fragment(const struct sk_buff *skb)
+{
+       return unlikely((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0) ||
+              !skb->local_df;
+}
+
+static bool ip_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
+{
+       if (skb->len <= mtu || skb->local_df)
+               return false;
+
+       if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
+               return false;
+
+       return true;
+}
+
+static bool ip_gso_exceeds_dst_mtu(const struct sk_buff *skb)
+{
+       unsigned int mtu;
+
+       if (skb->local_df || !skb_is_gso(skb))
+               return false;
+
+       mtu = ip_dst_mtu_maybe_forward(skb_dst(skb), true);
+
+       /* if seglen > mtu, do software segmentation for IP fragmentation on
+        * output.  DF bit cannot be set since ip_forward would have sent
+        * icmp error.
+        */
+       return skb_gso_network_seglen(skb) > mtu;
+}
+
+/* called if GSO skb needs to be fragmented on forward */
+static int ip_forward_finish_gso(struct sk_buff *skb)
+{
+       struct dst_entry *dst = skb_dst(skb);
+       netdev_features_t features;
+       struct sk_buff *segs;
+       int ret = 0;
+
+       features = netif_skb_dev_features(skb, dst->dev);
+       segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+       if (IS_ERR(segs)) {
+               kfree_skb(skb);
+               return -ENOMEM;
+       }
+
+       consume_skb(skb);
+
+       do {
+               struct sk_buff *nskb = segs->next;
+               int err;
+
+               segs->next = NULL;
+               err = dst_output(segs);
+
+               if (err && ret == 0)
+                       ret = err;
+               segs = nskb;
+       } while (segs);
+
+       return ret;
+}
+
 static int ip_forward_finish(struct sk_buff *skb)
 {
        struct ip_options *opt  = &(IPCB(skb)->opt);
@@ -49,6 +114,9 @@ static int ip_forward_finish(struct sk_buff *skb)
        if (unlikely(opt->optlen))
                ip_forward_options(skb);
 
+       if (ip_gso_exceeds_dst_mtu(skb))
+               return ip_forward_finish_gso(skb);
+
        return dst_output(skb);
 }
 
@@ -91,8 +159,7 @@ int ip_forward(struct sk_buff *skb)
 
        IPCB(skb)->flags |= IPSKB_FORWARDED;
        mtu = ip_dst_mtu_maybe_forward(&rt->dst, true);
-       if (unlikely(skb->len > mtu && !skb_is_gso(skb) &&
-                    (ip_hdr(skb)->frag_off & htons(IP_DF))) && !skb->local_df) {
+       if (!ip_may_fragment(skb) && ip_exceeds_mtu(skb, mtu)) {
                IP_INC_STATS(dev_net(rt->dst.dev), IPSTATS_MIB_FRAGFAILS);
                icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
                          htonl(mtu));