ipv4: raw: check sk->sk_rcvbuf earlier

There is no point cloning an skb and having to free the clone
if the receive queue of the raw socket is full.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240307163020.2524409-1-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/raw.c

@@ -175,6 +175,13 @@ static int raw_v4_input(struct net *net, struct sk_buff *skb,
 		if (!raw_v4_match(net, sk, iph->protocol,
 				  iph->saddr, iph->daddr, dif, sdif))
 			continue;
+
+		if (atomic_read(&sk->sk_rmem_alloc) >=
+		    READ_ONCE(sk->sk_rcvbuf)) {
+			atomic_inc(&sk->sk_drops);
+			continue;
+		}
+
 		delivered = 1;
 		if ((iph->protocol != IPPROTO_ICMP || !icmp_filter(sk, skb)) &&
 		    ip_mc_sf_allow(sk, iph->daddr, iph->saddr,