net: ip: make ip_route_input_noref() return drop reasons

In this commit, we make ip_route_input_noref() return drop reasons, which
come from ip_route_input_rcu().

We need adjust the callers of ip_route_input_noref() to make sure the
return value of ip_route_input_noref() is used properly.

The errno that ip_route_input_noref() returns comes from ip_route_input
and bpf_lwt_input_reroute in the origin logic, and we make them return
-EINVAL on error instead. In the following patch, we will make
ip_route_input() returns drop reasons too.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index c40a26972884..513eb0c6435a 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -362,10 +362,11 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
 	 *	how the packet travels inside Linux networking.
 	 */
 	if (!skb_valid_dst(skb)) {
-		err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
-					   ip4h_dscp(iph), dev);
-		if (unlikely(err))
+		drop_reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+						   ip4h_dscp(iph), dev);
+		if (unlikely(drop_reason))
 			goto drop_error;
+		drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	} else {
 		struct in_device *in_dev = __in_dev_get_rcu(dev);