/*
* L2TPv3 IP encapsulation support
*
* Copyright (c) 2008,2009,2010 Katalix Systems Ltd
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/icmp.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/random.h>
#include <linux/socket.h>
#include <linux/l2tp.h>
#include <linux/in.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/tcp_states.h>
#include <net/protocol.h>
#include <net/xfrm.h>
#include "l2tp_core.h"
struct l2tp_ip_sock {
/* inet_sock has to be the first member of l2tp_ip_sock */
struct inet_sock inet;
__u32 conn_id;
__u32 peer_conn_id;
__u64 tx_packets;
__u64 tx_bytes;
__u64 tx_errors;
__u64 rx_packets;
__u64 rx_bytes;
__u64 rx_errors;
};
static DEFINE_RWLOCK(l2tp_ip_lock);
static struct hlist_head l2tp_ip_table;
static struct hlist_head l2tp_ip_bind_table;
static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
{
return (struct l2tp_ip_sock *)sk;
}
static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
{
struct hlist_node *node;
struct sock *sk;
sk_for_each_bound(sk, node, &l2tp_ip_bind_table) {
struct inet_sock *inet = inet_sk(sk);
struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
if (l2tp == NULL)
continue;
if ((l2tp->conn_id == tunnel_id) &&
#ifdef CONFIG_NET_NS
(sk->sk_net == net) &&
#endif
!(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) &&
!(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
goto found;
}
sk = NULL;
found:
return sk;
}
static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
{
struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
if (sk)
sock_hold(sk);
return sk;
}
/* When processing receive frames, there are two cases to
* consider. Data frames consist of a non-zero session-id and an
* optional cookie. Control frames consist of a regular L2TP header
* preceded by 32-bits of zeros.
*
* L2TPv3 Session Header Over IP
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Session ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Cookie (optional, maximum 64 bits)...
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* L2TPv3 Control Message Header Over IP
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | (32 bits of zeros) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Control Connection ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Ns | Nr |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* All control frames are passed to userspace.
*/
static int l2tp_ip_recv(struct sk_buff *skb)
{
struct sock *sk;
u32 session_id;
u32 tunnel_id;
unsigned char *ptr, *optr;
struct l2tp_session *session;
struct l2tp_tunnel *tunnel = NULL;
int length;
int offset;
/* Point to L2TP header */
optr = ptr = skb->data;
if (!pskb_may_pull(skb, 4))
goto discard;
session_id = ntohl(*((__be32 *) ptr));
ptr += 4;
/* RFC3931: L2TP/IP packets have the first 4 bytes containing
* the session_id. If it is 0, the packet is a L2TP control
* frame and the session_id value can be discarded.
*/
if (session_id == 0) {
__skb_pull(skb, 4);
goto pass_up;
}
/* Ok, this is a data packet. Lookup the session. */
session = l2tp_session_find(&init_net, NULL, session_id);
if (session == NULL)
goto discard;
tunnel = session->tunnel;
if (tunnel == NULL)
goto discard;
/* Trace packet contents, if enabled */
if (tunnel->debug & L2TP_MSG_DATA) {
length = min(32u, skb->len);
if (!pskb_may_pull(skb, length))
goto discard;
printk(KERN_DEBUG "%s: ip recv: ", tunnel->name);
offset = 0;
do {
printk(" %02X", ptr[offset]);
} while (++offset < length);
printk("\n");
}
l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
return 0;
pass_up:
/* Get the tunnel_id from the L2TP header */
if (!pskb_may_pull(skb, 12))
goto discard;
if ((skb->data[0] & 0xc0) != 0xc0)
goto discard;
tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
if (tunnel != NULL)
sk = tunnel->sock;
else {
struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
read_lock_bh(&l2tp_ip_lock);
sk = __l2tp_ip_bind_lookup(&init_net, iph->daddr, 0, tunnel_id);
read_unlock_bh(&l2tp_ip_lock);
}
if (sk == NULL)
goto discard;
sock_hold(sk);
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_put;
nf_reset(skb);
return sk_receive_skb(sk, skb, 1);
discard_put:
sock_put(sk);
discard:
kfree_skb(skb);
return 0;
}
static int l2tp_ip_open(struct sock *sk)
{
/* Prevent autobind. We don't have ports. */
inet_sk(sk)->inet_num = IPPROTO_L2TP;
write_lock_bh(&l2tp_ip_lock);
sk_add_node(sk, &l2tp_ip_table);
write_unlock_bh(&l2tp_ip_lock);
return 0;
}
static void l2tp_ip_close(struct sock *sk, long timeout)
{
write_lock_bh(&l2tp_ip_lock);
hlist_del_init(&sk->sk_bind_node);
hlist_del_init(&sk->sk_node);
write_unlock_bh(&l2tp_ip_lock);
sk_common_release(sk);
}
static void l2tp_ip_destroy_sock(struct sock *sk)
{
struct sk_buff *skb;
while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
kfree_skb(skb);
sk_refcnt_debug_dec(sk);
}
static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
struct inet_sock *inet = inet_sk(sk);
struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
int ret = -EINVAL;
int chk_addr_ret;
ret = -EADDRINUSE;
read_lock_bh(&l2tp_ip_lock);
if (__l2tp_ip_bind_lookup(&init_net, addr->l2tp_addr.s_addr, sk->sk_bound_dev_if, addr->l2tp_conn_id))
goto out_in_use;
read_unlock_bh(&l2tp_ip_lock);
lock_sock(sk);
if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
goto out;
chk_addr_ret = inet_addr_type(&init_net, addr->l2tp_addr.s_addr);
ret = -EADDRNOTAVAIL;
if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
goto out;
inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
inet->inet_saddr = 0; /* Use device */
sk_dst_reset(sk);
l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
write_lock_bh(&l2tp_ip_lock);
sk_add_bind_node(sk, &l2tp_ip_bind_table);
sk_del_node_init(sk);
write_unlock_bh(&l2tp_ip_lock);
ret = 0;
out:
release_sock(sk);
return ret;
out_in_use:
read_unlock_bh(&l2tp_ip_lock);
return ret;
}
static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
int rc;
struct inet_sock *inet = inet_sk(sk);
struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
struct rtable *rt;
__be32 saddr;
int oif;
rc = -EINVAL;
if (addr_len < sizeof(*lsa))
goto out;
rc = -EAFNOSUPPORT;
if (lsa->l2tp_family != AF_INET)
goto out;
sk_dst_reset(sk);
oif = sk->sk_bound_dev_if;
saddr = inet->inet_saddr;
rc = -EINVAL;
if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
goto out;
rc = ip_route_connect(&rt, lsa->l2tp_addr.s_addr, saddr,
RT_CONN_FLAGS(sk), oif,
IPPROTO_L2TP,
0, 0, sk, 1);
if (rc) {
if (rc == -ENETUNREACH)
IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES);
goto out;
}
rc = -ENETUNREACH;
if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
ip_rt_put(rt);
goto out;
}
l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
if (!inet->inet_saddr)
inet->inet_saddr = rt->rt_src;
if (!inet->inet_rcv_saddr)
inet->inet_rcv_saddr = rt->rt_src;
inet->inet_daddr = rt->rt_dst;
sk->sk_state = TCP_ESTABLISHED;
inet->inet_id = jiffies;
sk_dst_set(sk, &rt->dst);
write_lock_bh(&l2tp_ip_lock);
hlist_del_init(&sk->sk_bind_node);
sk_add_bind_node(sk, &l2tp_ip_bind_table);
write_unlock_bh(&l2tp_ip_lock);
rc = 0;
out:
return rc;
}
static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
int *uaddr_len, int peer)
{
struct sock *sk = sock->sk;
struct inet_sock *inet = inet_sk(sk);
struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
memset(lsa, 0, sizeof(*lsa));
lsa->l2tp_family = AF_INET;
if (peer) {
if (!inet->inet_dport)
return -ENOTCONN;
lsa->l2tp_conn_id = lsk->peer_conn_id;
lsa->l2tp_addr.s_addr = inet->inet_daddr;
} else {
__be32 addr = inet->inet_rcv_saddr;
if (!addr)
addr = inet->inet_saddr;
lsa->l2tp_conn_id = lsk->conn_id;
lsa->l2tp_addr.s_addr = addr;
}
*uaddr_len = sizeof(*lsa);
return 0;
}
static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
{
int rc;
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
goto drop;
nf_reset(skb);
/* Charge it to the socket, dropping if the queue is full. */
rc = sock_queue_rcv_skb(sk, skb);
if (rc < 0)
goto drop;
return 0;
drop:
IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
kfree_skb(skb);
return -1;
}
/* Userspace will call sendmsg() on the tunnel socket to send L2TP
* control frames.
*/
static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
{
struct sk_buff *skb;
int rc;
struct l2tp_ip_sock *lsa = l2tp_ip_sk(sk);
struct inet_sock *inet = inet_sk(sk);
struct ip_options *opt = inet->opt;
struct rtable *rt = NULL;
int connected = 0;
__be32 daddr;
if (sock_flag(sk, SOCK_DEAD))
return -ENOTCONN;
/* Get and verify the address. */
if (msg->msg_name) {
struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name;
if (msg->msg_namelen < sizeof(*lip))
return -EINVAL;
if (lip->l2tp_family != AF_INET) {
if (lip->l2tp_family != AF_UNSPEC)
return -EAFNOSUPPORT;
}
daddr = lip->l2tp_addr.s_addr;
} else {
if (sk->sk_state != TCP_ESTABLISHED)
return -EDESTADDRREQ;
daddr = inet->inet_daddr;
connected = 1;
}
/* Allocate a socket buffer */
rc = -ENOMEM;
skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
4 + len, 0, GFP_KERNEL);
if (!skb)
goto error;
/* Reserve space for headers, putting IP header on 4-byte boundary. */
skb_reserve(skb, 2 + NET_SKB_PAD);
skb_reset_network_header(skb);
skb_reserve(skb, sizeof(struct iphdr));
skb_reset_transport_header(skb);
/* Insert 0 session_id */
*((__be32 *) skb_put(skb, 4)) = 0;
/* Copy user data into skb */
rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
if (rc < 0) {
kfree_skb(skb);
goto error;
}
if (connected)
rt = (struct rtable *) __sk_dst_check(sk, 0);
if (rt == NULL) {
/* Use correct destination address if we have options. */
if (opt && opt->srr)
daddr = opt->faddr;
{
struct flowi fl = { .oif = sk->sk_bound_dev_if,
.nl_u = { .ip4_u = {
.daddr = daddr,
.saddr = inet->inet_saddr,
.tos = RT_CONN_FLAGS(sk) } },
.proto = sk->sk_protocol,
.flags = inet_sk_flowi_flags(sk),
.uli_u = { .ports = {
.sport = inet->inet_sport,
.dport = inet->inet_dport } } };
/* If this fails, retransmit mechanism of transport layer will
* keep trying until route appears or the connection times
* itself out.
*/
security_sk_classify_flow(sk, &fl);
if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0))
goto no_route;
}
sk_setup_caps(sk, &rt->dst);
}
skb_dst_set(skb, dst_clone(&rt->dst));
/* Queue the packet to IP for output */
rc = ip_queue_xmit(skb);
error:
/* Update stats */
if (rc >= 0) {
lsa->tx_packets++;
lsa->tx_bytes += len;
rc = len;
} else {
lsa->tx_errors++;
}
return rc;
no_route:
IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
kfree_skb(skb);
return -EHOSTUNREACH;
}
static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t len, int noblock, int flags, int *addr_len)
{
struct inet_sock *inet = inet_sk(sk);
struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
size_t copied = 0;
int err = -EOPNOTSUPP;
struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
struct sk_buff *skb;
if (flags & MSG_OOB)
goto out;
if (addr_len)
*addr_len = sizeof(*sin);
skb = skb_recv_datagram(sk, flags, noblock, &err);
if (!skb)
goto out;
copied = skb->len;
if (len < copied) {
msg->msg_flags |= MSG_TRUNC;
copied = len;
}
err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
if (err)
goto done;
sock_recv_timestamp(msg, sk, skb);
/* Copy the address. */
if (sin) {
sin->sin_family = AF_INET;
sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
sin->sin_port = 0;
memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
}
if (inet->cmsg_flags)
ip_cmsg_recv(msg, skb);
if (flags & MSG_TRUNC)
copied = skb->len;
done:
skb_free_datagram(sk, skb);
out:
if (err) {
lsk->rx_errors++;
return err;
}
lsk->rx_packets++;
lsk->rx_bytes += copied;
return copied;
}
struct proto l2tp_ip_prot = {
.name = "L2TP/IP",
.owner = THIS_MODULE,
.init = l2tp_ip_open,
.close = l2tp_ip_close,
.bind = l2tp_ip_bind,
.connect = l2tp_ip_connect,
.disconnect = udp_disconnect,
.ioctl = udp_ioctl,
.destroy = l2tp_ip_destroy_sock,
.setsockopt = ip_setsockopt,
.getsockopt = ip_getsockopt,
.sendmsg = l2tp_ip_sendmsg,
.recvmsg = l2tp_ip_recvmsg,
.backlog_rcv = l2tp_ip_backlog_recv,
.hash = inet_hash,
.unhash = inet_unhash,
.obj_size = sizeof(struct l2tp_ip_sock),
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_ip_setsockopt,
.compat_getsockopt = compat_ip_getsockopt,
#endif
};
static const struct proto_ops l2tp_ip_ops = {
.family = PF_INET,
.owner = THIS_MODULE,
.release = inet_release,
.bind = inet_bind,
.connect = inet_dgram_connect,
.socketpair = sock_no_socketpair,
.accept = sock_no_accept,
.getname = l2tp_ip_getname,
.poll = datagram_poll,
.ioctl = inet_ioctl,
.listen = sock_no_listen,
.shutdown = inet_shutdown,
.setsockopt = sock_common_setsockopt,
.getsockopt = sock_common_getsockopt,
.sendmsg = inet_sendmsg,
.recvmsg = sock_common_recvmsg,
.mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_sock_common_setsockopt,
.compat_getsockopt = compat_sock_common_getsockopt,
#endif
};
static struct inet_protosw l2tp_ip_protosw = {
.type = SOCK_DGRAM,
.protocol = IPPROTO_L2TP,
.prot = &l2tp_ip_prot,
.ops = &l2tp_ip_ops,
.no_check = 0,
};
static struct net_protocol l2tp_ip_protocol __read_mostly = {
.handler = l2tp_ip_recv,
};
static int __init l2tp_ip_init(void)
{
int err;
printk(KERN_INFO "L2TP IP encapsulation support (L2TPv3)\n");
err = proto_register(&l2tp_ip_prot, 1);
if (err != 0)
goto out;
err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
if (err)
goto out1;
inet_register_protosw(&l2tp_ip_protosw);
return 0;
out1:
proto_unregister(&l2tp_ip_prot);
out:
return err;
}
static void __exit l2tp_ip_exit(void)
{
inet_unregister_protosw(&l2tp_ip_protosw);
inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
proto_unregister(&l2tp_ip_prot);
}
module_init(l2tp_ip_init);
module_exit(l2tp_ip_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("L2TP over IP");
MODULE_VERSION("1.0");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, SOCK_DGRAM, IPPROTO_L2TP);
