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 <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index a4e37d7..aa1a9d4 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -495,52 +495,6 @@
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 @@
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 @@
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));