fib_rules: add route suppression based on ifgroup

This change adds the ability to suppress a routing decision based upon the
interface group the selected interface belongs to. This allows it to
exclude specific devices from a routing decision.

Signed-off-by: Stefan Tomanek <stefan.tomanek@wertarbyte.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 2ef5040..5040a61 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -343,6 +343,9 @@
 	if (tb[FRA_TABLE_PREFIXLEN_MIN])
 		rule->table_prefixlen_min = nla_get_u8(tb[FRA_TABLE_PREFIXLEN_MIN]);
 
+	if (tb[FRA_SUPPRESS_IFGROUP])
+		rule->suppress_ifgroup = nla_get_u32(tb[FRA_SUPPRESS_IFGROUP]);
+
 	if (!tb[FRA_PRIORITY] && ops->default_pref)
 		rule->pref = ops->default_pref(ops);
 
@@ -529,6 +532,7 @@
 			 + nla_total_size(4) /* FRA_PRIORITY */
 			 + nla_total_size(4) /* FRA_TABLE */
 			 + nla_total_size(1) /* FRA_TABLE_PREFIXLEN_MIN */
+			 + nla_total_size(4) /* FRA_SUPPRESS_IFGROUP */
 			 + nla_total_size(4) /* FRA_FWMARK */
 			 + nla_total_size(4); /* FRA_FWMASK */
 
@@ -588,6 +592,12 @@
 	    (rule->target &&
 	     nla_put_u32(skb, FRA_GOTO, rule->target)))
 		goto nla_put_failure;
+
+	if (rule->suppress_ifgroup != -1) {
+		if (nla_put_u32(skb, FRA_SUPPRESS_IFGROUP, rule->suppress_ifgroup))
+			goto nla_put_failure;
+	}
+
 	if (ops->fill(rule, skb, frh) < 0)
 		goto nla_put_failure;