[PATCH] nfnetlink_log mac address for 6in4 tunnels

[Bob Hockney <bhockney@ix.netcom.com>]

For tunnelled ipv6in4 packets, the LOG target (xt_LOG.c) adjusts the start of the mac field to start at the ethernet header instead of the ipv4 header for the tunnel.  This patch conforms what is passed by the NFLOG target through nfnetlink to what the LOG target does.  Code borrowed from xt_LOG.c.

===
--- a/net/netfilter/nfnetlink_log.c        2012-11-28 17:11:02.285514325 -0700
+++ b/net/netfilter/nfnetlink_log.c 2012-11-28 17:10:38.551830948 -0700
@@ -382,6 +382,7 @@
        struct nfgenmsg *nfmsg;
        sk_buff_data_t old_tail = inst->skb->tail;
        struct sock *sk;
+       const unsigned char *hwhdrp;

        nlh = nlmsg_put(inst->skb, 0, 0,
                        NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET,
@@ -483,9 +484,16 @@
        if (indev && skb_mac_header_was_set(skb)) {
                if (nla_put_be16(inst->skb, NFULA_HWTYPE, htons(skb->dev->type)) ||
                    nla_put_be16(inst->skb, NFULA_HWLEN,
-                                htons(skb->dev->hard_header_len)) ||
-                   nla_put(inst->skb, NFULA_HWHEADER, skb->dev->hard_header_len,
-                           skb_mac_header(skb)))
+                                htons(skb->dev->hard_header_len)))
+                       goto nla_put_failure;
+
+               hwhdrp = skb_mac_header(skb);
+
+               if (skb->dev->type == ARPHRD_SIT)
+                       hwhdrp -= ETH_HLEN;
+
+               if (!(hwhdrp < skb->head) && nla_put(inst->skb, NFULA_HWHEADER,
+                           skb->dev->hard_header_len, hwhdrp))
                        goto nla_put_failure;
        }