From df90e6886146dd744eb3929782e6df9749cd4a69 Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Tue, 29 Nov 2016 13:09:47 +0100 Subject: l2tp: fix lookup for sockets not bound to a device in l2tp_ip When looking up an l2tp socket, we must consider a null netdevice id as wild card. There are currently two problems caused by __l2tp_ip_bind_lookup() not considering 'dif' as wild card when set to 0: * A socket bound to a device (i.e. with sk->sk_bound_dev_if != 0) never receives any packet. Since __l2tp_ip_bind_lookup() is called with dif == 0 in l2tp_ip_recv(), sk->sk_bound_dev_if is always different from 'dif' so the socket doesn't match. * Two sockets, one bound to a device but not the other, can be bound to the same address. If the first socket binding to the address is the one that is also bound to a device, the second socket can bind to the same address without __l2tp_ip_bind_lookup() noticing the overlap. To fix this issue, we need to consider that any null device index, be it 'sk->sk_bound_dev_if' or 'dif', matches with any other value. We also need to pass the input device index to __l2tp_ip_bind_lookup() on reception so that sockets bound to a device never receive packets from other devices. This patch fixes l2tp_ip6 in the same way. Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller --- net/l2tp/l2tp_ip.c | 6 ++++-- net/l2tp/l2tp_ip6.c | 7 ++++--- 2 files changed, 8 insertions(+), 5 deletions(-) (limited to 'net/l2tp') diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index b517c3366922..8938b6ba57a0 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -61,7 +61,8 @@ static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif if ((l2tp->conn_id == tunnel_id) && net_eq(sock_net(sk), net) && !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) && - !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)) + (!sk->sk_bound_dev_if || !dif || + sk->sk_bound_dev_if == dif)) goto found; } @@ -182,7 +183,8 @@ pass_up: struct iphdr *iph = (struct iphdr *) skb_network_header(skb); read_lock_bh(&l2tp_ip_lock); - sk = __l2tp_ip_bind_lookup(net, iph->daddr, 0, tunnel_id); + sk = __l2tp_ip_bind_lookup(net, iph->daddr, inet_iif(skb), + tunnel_id); if (!sk) { read_unlock_bh(&l2tp_ip_lock); goto discard; diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index 5f2ae615c5f9..4a8644001d09 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -73,7 +73,8 @@ static struct sock *__l2tp_ip6_bind_lookup(struct net *net, if ((l2tp->conn_id == tunnel_id) && net_eq(sock_net(sk), net) && !(addr && ipv6_addr_equal(addr, laddr)) && - !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)) + (!sk->sk_bound_dev_if || !dif || + sk->sk_bound_dev_if == dif)) goto found; } @@ -196,8 +197,8 @@ pass_up: struct ipv6hdr *iph = ipv6_hdr(skb); read_lock_bh(&l2tp_ip6_lock); - sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, - 0, tunnel_id); + sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, inet6_iif(skb), + tunnel_id); if (!sk) { read_unlock_bh(&l2tp_ip6_lock); goto discard; -- cgit