Change 4000258 by mbligh@mbligh-src1 on 2006/09/28 13:32:25

	NOTE: The routing cache has to be cleared after enabling/disabling
	this tunable for it to take effect.
	
--- a/2.6.18/include/linux/sysctl.h
+++ b/2.6.18/include/linux/sysctl.h
@@ -462,6 +462,7 @@ enum {
 	NET_IPV4_ROUTE_MIN_ADVMSS=17,
 	NET_IPV4_ROUTE_SECRET_INTERVAL=18,
 	NET_IPV4_ROUTE_GC_MIN_INTERVAL_MS=19,
+	NET_IPV4_ROUTE_NO_LOCAL_LOOPBACK=GOOGLE_SYSCTL(1),
 };
 
 enum
--- a/2.6.18/include/net/ip_fib.h
+++ b/2.6.18/include/net/ip_fib.h
@@ -192,6 +192,13 @@ static inline int fib_lookup(const struc
 	return 0;
 }
 
+static inline int fib_lookup_nolocal(const struct flowi *flp, struct fib_result *res)
+{
+	if (ip_fib_main_table->tb_lookup(ip_fib_main_table, flp, res))
+		return -ENETUNREACH;
+	return 0;
+}
+
 static inline void fib_select_default(const struct flowi *flp, struct fib_result *res)
 {
 	if (FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK)
--- a/2.6.18/net/ipv4/route.c
+++ b/2.6.18/net/ipv4/route.c
@@ -132,6 +132,7 @@ static int ip_rt_mtu_expires		= 10 * 60 
 static int ip_rt_min_pmtu		= 512 + 20 + 20;
 static int ip_rt_min_advmss		= 256;
 static int ip_rt_secret_interval	= 10 * 60 * HZ;
+int ip_rt_no_local_loopback		= 0;
 static unsigned long rt_deadline;
 
 #define RTprint(a...)	printk(KERN_DEBUG a)
@@ -1968,7 +1969,7 @@ static int ip_route_input_slow(struct sk
 		result = fib_validate_source(saddr, daddr, tos,
 					     loopback_dev.ifindex,
 					     dev, &spec_dst, &itag);
-		if (result < 0)
+		if (result < 0 && (!ip_rt_no_local_loopback))
 			goto martian_source;
 		if (result)
 			flags |= RTCF_DIRECTSRC;
@@ -2484,7 +2485,8 @@ static int ip_route_output_slow(struct r
 		goto make_route;
 	}
 
-	if (fib_lookup(&fl, &res)) {
+	if (ip_rt_no_local_loopback?fib_lookup_nolocal(&fl, &res):
+	                            fib_lookup(&fl, &res)) {
 		res.fi = NULL;
 		if (oldflp->oif) {
 			/* Apparently, routing tables are wrong. Assume,
@@ -3057,6 +3059,14 @@ ctl_table ipv4_route_table[] = {
 		.proc_handler	= &proc_dointvec_jiffies,
 		.strategy	= &sysctl_jiffies,
 	},
+	{
+		.ctl_name	= NET_IPV4_ROUTE_NO_LOCAL_LOOPBACK,
+		.procname	= "no_local_loopback",
+		.data		= &ip_rt_no_local_loopback,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 	{ .ctl_name = 0 }
 };
 #endif
--- a/2.6.18/net/ipv4/tcp_input.c
+++ b/2.6.18/net/ipv4/tcp_input.c
@@ -94,6 +94,8 @@ int sysctl_tcp_nometrics_save;
 int sysctl_tcp_moderate_rcvbuf = 1;
 int sysctl_tcp_abc;
 
+extern int ip_rt_no_local_loopback;
+
 #define FLAG_DATA		0x01 /* Incoming frame contained data.		*/
 #define FLAG_WIN_UPDATE		0x02 /* Incoming ACK was a window update.	*/
 #define FLAG_DATA_ACKED		0x04 /* This ACK acknowledged new data.		*/
@@ -2561,7 +2563,7 @@ static int tcp_ack(struct sock *sk, stru
 	sk->sk_err_soft = 0;
 
 	/* we have just done some useful work. Kick the watchdog. */
-	if ((inet->rcv_saddr != inet->daddr  &&
+	if (((inet->rcv_saddr != inet->daddr || ip_rt_no_local_loopback )  &&
 		(ntohl(inet->rcv_saddr) & 0xff000000) != 0x7f000000 &&
 		(ntohl(inet->daddr) & 0xff000000) != 0x7f000000)||
 		(skb->dev &&  !(skb->dev->flags & IFF_LOOPBACK))) {