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l2tp: Remove UDP checksum verification

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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>
This commit is contained in:
Tom Herbert 2014-05-07 16:52:48 -07:00 committed by David S. Miller
parent 0a80966b10
commit 58d6085c14
1 changed files with 1 additions and 56 deletions
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57
net/l2tp/l2tp_core.c
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@ -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));