udp: use sk_filter_trim_cap for udp{,6}_queue_rcv_skb

borkmann · davem330 · commit ba66bbe5480a · 2016-07-25T21:40:33.000-07:00
After a612769 ("udp: prevent bugcheck if filter truncates packet too much"), there followed various other fixes for similar cases such as f4979fc ("rose: limit sk_filter trim to payload"). Latter introduced a new helper sk_filter_trim_cap(), where we can pass the trim limit directly to the socket filter handling. Make use of it here as well with sizeof(struct udphdr) as lower cap limit and drop the extra skb->len test in UDP's input path. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Willem de Bruijn <willemb@google.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
@@ -1581,9 +1581,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	    udp_lib_checksum_complete(skb))
 			goto csum_error;
 
-	if (sk_filter(sk, skb))
-		goto drop;
-	if (unlikely(skb->len < sizeof(struct udphdr)))
+	if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr)))
 		goto drop;
 
 	udp_csum_pull_header(skb);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
@@ -618,9 +618,7 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	    udp_lib_checksum_complete(skb))
 		goto csum_error;
 
-	if (sk_filter(sk, skb))
-		goto drop;
-	if (unlikely(skb->len < sizeof(struct udphdr)))
+	if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr)))
 		goto drop;
 
 	udp_csum_pull_header(skb);
