IPv6 routing, NLM_F_* flag support: warn if new route is created without NLM_F_CREATE

The support for NLM_F_* flags at IPv6 routing requests.

Warn if NLM_F_CREATE flag is not defined for RTM_NEWROUTE request,
creating new table. Later NLM_F_CREATE may be required for
new route creation.

Patch created against linux-3.2-rc1
Signed-off-by: NMatti Vaittinen <Mazziesaccount@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -1230,9 +1230,18 @@ int ip6_route_add(struct fib6_config *cfg)
 	if (cfg->fc_metric == 0)
 		cfg->fc_metric = IP6_RT_PRIO_USER;
 
-	table = fib6_new_table(net, cfg->fc_table);
+	err = -ENOBUFS;
+	if (NULL != cfg->fc_nlinfo.nlh &&
+	    !(cfg->fc_nlinfo.nlh->nlmsg_flags&NLM_F_CREATE)) {
+		table = fib6_get_table(net, cfg->fc_table);
+		if (table == NULL) {
+			printk(KERN_WARNING "IPv6: NLM_F_CREATE should be specified when creating new route\n");
+			table = fib6_new_table(net, cfg->fc_table);
+		}
+	} else {
+		table = fib6_new_table(net, cfg->fc_table);
+	}
 	if (table == NULL) {
-		err = -ENOBUFS;
 		goto out;
 	}