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>

1 files changed, 17 insertions, 6 deletions

diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 9f29066..b78fd28 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -103,16 +103,27 @@ errout:
 
 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 {
+	struct fib_result *result = (struct fib_result *) arg->result;
+	struct net_device *dev = result->fi->fib_dev;
+
 	/* do not accept result if the route does
 	 * not meet the required prefix length
 	 */
-	struct fib_result *result = (struct fib_result *) arg->result;
-	if (result->prefixlen < rule->table_prefixlen_min) {
-		if (!(arg->flags & FIB_LOOKUP_NOREF))
-			fib_info_put(result->fi);
-		return true;
-	}
+	if (result->prefixlen < rule->table_prefixlen_min)
+		goto suppress_route;
+
+	/* do not accept result if the route uses a device
+	 * belonging to a forbidden interface group
+	 */
+	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
+		goto suppress_route;
+
 	return false;
+
+suppress_route:
+	if (!(arg->flags & FIB_LOOKUP_NOREF))
+		fib_info_put(result->fi);
+	return true;
 }
 
 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)