ipv4: do metrics match when looking up and deleting a route

Now when ipv4 route inserts a fib_info, it memcmp fib_metrics.
It means ipv4 route identifies one route also with metrics.

But when removing a route, it tries to find the route without
caring about the metrics. It will cause that the route with
right metrics can't be removed.

Thomas noticed this issue when doing the testing:

1. add:
   # ip route append 192.168.7.0/24 dev v window 1000
   # ip route append 192.168.7.0/24 dev v window 1001
   # ip route append 192.168.7.0/24 dev v window 1002
   # ip route append 192.168.7.0/24 dev v window 1003
2. delete:
   # ip route delete 192.168.7.0/24 dev v window 1002
3. show:
     192.168.7.0/24 proto boot scope link window 1001
     192.168.7.0/24 proto boot scope link window 1002
     192.168.7.0/24 proto boot scope link window 1003

The one with window 1002 wasn't deleted but the first one was.

This patch is to do metrics match when looking up and deleting
one route.
Reported-by: Thomas Haller <thaller@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/fib_lookup.h

@@ -32,6 +32,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 				 struct netlink_ext_ack *extack);
 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 		 struct netlink_ext_ack *extack);
+bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi);
 int fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event, u32 tb_id,
 		  u8 type, __be32 dst, int dst_len, u8 tos, struct fib_info *fi,
 		  unsigned int);

net/ipv4/fib_semantics.c

@@ -696,6 +696,40 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 	return 0;
 }
 
+bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
+{
+	struct nlattr *nla;
+	int remaining;
+
+	if (!cfg->fc_mx)
+		return true;
+
+	nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
+		int type = nla_type(nla);
+		u32 val;
+
+		if (!type)
+			continue;
+		if (type > RTAX_MAX)
+			return false;
+
+		if (type == RTAX_CC_ALGO) {
+			char tmp[TCP_CA_NAME_MAX];
+			bool ecn_ca = false;
+
+			nla_strlcpy(tmp, nla, sizeof(tmp));
+			val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
+		} else {
+			val = nla_get_u32(nla);
+		}
+
+		if (fi->fib_metrics->metrics[type - 1] != val)
+			return false;
+	}
+
+	return true;
+}
+
 
 /*
  * Picture

net/ipv4/fib_trie.c

@@ -1563,7 +1563,8 @@ int fib_table_delete(struct net *net, struct fib_table *tb,
 		     fi->fib_prefsrc == cfg->fc_prefsrc) &&
 		    (!cfg->fc_protocol ||
 		     fi->fib_protocol == cfg->fc_protocol) &&
-		    fib_nh_match(cfg, fi, extack) == 0) {
+		    fib_nh_match(cfg, fi, extack) == 0 &&
+		    fib_metrics_match(cfg, fi)) {
 			fa_to_delete = fa;
 			break;
 		}