ipv4: support sport, dport and ip_proto in RTM_GETROUTE

This is a followup to fib rules sport, dport and ipproto
match support. Only supports tcp, udp and icmp for ipproto.
Used by fib rule self tests.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netlink.c b/net/ipv4/netlink.c
new file mode 100644
index 0000000..f86bb4f
--- /dev/null
+++ b/net/ipv4/netlink.c
@@ -0,0 +1,23 @@
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/types.h>
+#include <net/net_namespace.h>
+#include <net/netlink.h>
+#include <net/ip.h>
+
+int rtm_getroute_parse_ip_proto(struct nlattr *attr, u8 *ip_proto,
+				struct netlink_ext_ack *extack)
+{
+	*ip_proto = nla_get_u8(attr);
+
+	switch (*ip_proto) {
+	case IPPROTO_TCP:
+	case IPPROTO_UDP:
+	case IPPROTO_ICMP:
+		return 0;
+	default:
+		NL_SET_ERR_MSG(extack, "Unsupported ip proto");
+		return -EOPNOTSUPP;
+	}
+}
+EXPORT_SYMBOL_GPL(rtm_getroute_parse_ip_proto);