netfilter: nf_conntrack: properly account terminating packets

Currently the last packet of a connection isn't accounted when its causing
abnormal termination.

Introduces nf_ct_kill_acct() which increments the accounting counters on
conntrack kill. The new function was necessary, because there are calls
to nf_ct_kill() which don't need accounting:

nf_conntrack_proto_tcp.c line ~847:
Kills ct and returns NF_REPEAT. We don't want to count twice.

nf_conntrack_proto_tcp.c line ~880:
Kills ct and returns NF_DROP. I think we don't want to count dropped
packets.

nf_conntrack_netlink.c line ~824:
As far as I can see ctnetlink_del_conntrack() is used to destroy a
conntrack on behalf of the user. There is an sk_buff, but I don't think
this is an actual packet. Incrementing counters here is therefore not
desired.

Signed-off-by: Fabian Hugelshofer <[e-mail]>
Signed-off-by: Patrick McHardy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/netfilter/nf_conntrack.h

···
 	__nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, 0);
 }
 
-extern void nf_ct_kill(struct nf_conn *ct);
+extern void __nf_ct_kill_acct(struct nf_conn *ct,
+				enum ip_conntrack_info ctinfo,
+				const struct sk_buff *skb,
+				int do_acct);
+
+/* kill conntrack and do accounting */
+static inline void nf_ct_kill_acct(struct nf_conn *ct,
+				enum ip_conntrack_info ctinfo,
+				const struct sk_buff *skb)
+{
+	__nf_ct_kill_acct(ct, ctinfo, skb, 1);
+}
+
+/* kill conntrack without accounting */
+static inline void nf_ct_kill(struct nf_conn *ct)
+{
+	__nf_ct_kill_acct(ct, 0, NULL, 0);
+}
 
 /* These are for NAT.  Icky. */
 /* Update TCP window tracking data when NAT mangles the packet */

net/ipv4/netfilter/nf_conntrack_proto_icmp.c

···
 	   (theoretically possible with SMP) */
 	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 		if (atomic_dec_and_test(&ct->proto.icmp.count))
-			nf_ct_kill(ct);
+			nf_ct_kill_acct(ct, ctinfo, skb);
 	} else {
 		atomic_inc(&ct->proto.icmp.count);
 		nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);

net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c

···
 	   (theoretically possible with SMP) */
 	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 		if (atomic_dec_and_test(&ct->proto.icmp.count))
-			nf_ct_kill(ct);
+			nf_ct_kill_acct(ct, ctinfo, skb);
 	} else {
 		atomic_inc(&ct->proto.icmp.count);
 		nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);

net/netfilter/nf_conntrack_core.c

···
 }
 EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
 
-void nf_ct_kill(struct nf_conn *ct)
+void __nf_ct_kill_acct(struct nf_conn *ct,
+		enum ip_conntrack_info ctinfo,
+		const struct sk_buff *skb,
+		int do_acct)
 {
+#ifdef CONFIG_NF_CT_ACCT
+	if (do_acct) {
+		spin_lock_bh(&nf_conntrack_lock);
+		ct->counters[CTINFO2DIR(ctinfo)].packets++;
+		ct->counters[CTINFO2DIR(ctinfo)].bytes +=
+			skb->len - skb_network_offset(skb);
+		spin_unlock_bh(&nf_conntrack_lock);
+	}
+#endif
 	if (del_timer(&ct->timeout))
 		ct->timeout.function((unsigned long)ct);
 }
-EXPORT_SYMBOL_GPL(nf_ct_kill);
+EXPORT_SYMBOL_GPL(__nf_ct_kill_acct);
 
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 

net/netfilter/nf_conntrack_proto_dccp.c

···
 	if (type == DCCP_PKT_RESET &&
 	    !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 		/* Tear down connection immediately if only reply is a RESET */
-		nf_ct_kill(ct);
+		nf_ct_kill_acct(ct, ctinfo, skb);
 		return NF_ACCEPT;
 	}
 

net/netfilter/nf_conntrack_proto_tcp.c

···
 		   problem case, so we can delete the conntrack
 		   immediately.  --RR */
 		if (th->rst) {
-			nf_ct_kill(ct);
+			nf_ct_kill_acct(ct, ctinfo, skb);
 			return NF_ACCEPT;
 		}
 	} else if (!test_bit(IPS_ASSURED_BIT, &ct->status)