From 58d6085c14f5db61c092c90b59813397bc771417 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Wed, 7 May 2014 16:52:48 -0700 Subject: [PATCH] l2tp: Remove UDP checksum verification Validating the UDP checksum is now done in UDP before handing packets to the encapsulation layer. Note that this also eliminates the "feature" where L2TP can ignore a non-zero UDP checksum (doing this was contrary to RFC 1122). Signed-off-by: Tom Herbert Signed-off-by: David S. Miller --- net/l2tp/l2tp_core.c | 57 +------------------------------------------- 1 file changed, 1 insertion(+), 56 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index a4e37d7158dc..aa1a9d44c107 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -495,52 +495,6 @@ out: spin_unlock_bh(&session->reorder_q.lock); } -static inline int l2tp_verify_udp_checksum(struct sock *sk, - struct sk_buff *skb) -{ - struct udphdr *uh = udp_hdr(skb); - u16 ulen = ntohs(uh->len); - __wsum psum; - - if (sk->sk_no_check || skb_csum_unnecessary(skb)) - return 0; - -#if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family == PF_INET6 && !l2tp_tunnel(sk)->v4mapped) { - if (!uh->check) { - LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n"); - return 1; - } - if ((skb->ip_summed == CHECKSUM_COMPLETE) && - !csum_ipv6_magic(&ipv6_hdr(skb)->saddr, - &ipv6_hdr(skb)->daddr, ulen, - IPPROTO_UDP, skb->csum)) { - skb->ip_summed = CHECKSUM_UNNECESSARY; - return 0; - } - skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr, - &ipv6_hdr(skb)->daddr, - skb->len, IPPROTO_UDP, - 0)); - } else -#endif - { - struct inet_sock *inet; - if (!uh->check) - return 0; - inet = inet_sk(sk); - psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, - ulen, IPPROTO_UDP, 0); - - if ((skb->ip_summed == CHECKSUM_COMPLETE) && - !csum_fold(csum_add(psum, skb->csum))) - return 0; - skb->csum = psum; - } - - return __skb_checksum_complete(skb); -} - static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) { u32 nws; @@ -895,8 +849,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, u16 version; int length; - if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb)) - goto discard_bad_csum; + /* UDP has verifed checksum */ /* UDP always verifies the packet length. */ __skb_pull(skb, sizeof(struct udphdr)); @@ -979,14 +932,6 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, return 0; -discard_bad_csum: - LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name); - UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0); - atomic_long_inc(&tunnel->stats.rx_errors); - kfree_skb(skb); - - return 0; - error: /* Put UDP header back */ __skb_push(skb, sizeof(struct udphdr)); -- 2.20.1