1 /* drivers/net/pppolac.c
3 * Driver for PPP on L2TP Access Concentrator / PPPoLAC Socket (RFC 2661)
5 * Copyright (C) 2009 Google, Inc.
7 * This software is licensed under the terms of the GNU General Public
8 * License version 2, as published by the Free Software Foundation, and
9 * may be copied, distributed, and modified under those terms.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
17 /* This driver handles L2TP data packets between a UDP socket and a PPP channel.
18 * To keep things simple, only one session per socket is permitted. Packets are
19 * sent via the socket, so it must keep connected to the same address. One must
20 * not set sequencing in ICCN but let LNS controll it. Currently this driver
21 * only works on IPv4 due to the lack of UDP encapsulation support in IPv6. */
23 #include <linux/module.h>
24 #include <linux/workqueue.h>
25 #include <linux/skbuff.h>
26 #include <linux/file.h>
27 #include <linux/netdevice.h>
28 #include <linux/net.h>
29 #include <linux/udp.h>
30 #include <linux/ppp_defs.h>
31 #include <linux/if_ppp.h>
32 #include <linux/if_pppox.h>
33 #include <linux/ppp_channel.h>
34 #include <net/tcp_states.h>
35 #include <asm/uaccess.h>
37 #define L2TP_CONTROL_BIT 0x80
38 #define L2TP_LENGTH_BIT 0x40
39 #define L2TP_SEQUENCE_BIT 0x08
40 #define L2TP_OFFSET_BIT 0x02
41 #define L2TP_VERSION 0x02
42 #define L2TP_VERSION_MASK 0x0F
49 } __attribute__((packed));
51 static inline union unaligned *unaligned(void *ptr)
53 return (union unaligned *)ptr;
56 static int pppolac_recv_core(struct sock *sk_udp, struct sk_buff *skb)
58 struct sock *sk = (struct sock *)sk_udp->sk_user_data;
59 struct pppolac_opt *opt = &pppox_sk(sk)->proto.lac;
63 /* Drop the packet if it is too short. */
64 if (skb->len < sizeof(struct udphdr) + 6)
67 /* Put it back if it is a control packet. */
68 if (skb->data[sizeof(struct udphdr)] & L2TP_CONTROL_BIT)
69 return opt->backlog_rcv(sk_udp, skb);
71 /* Skip UDP header. */
72 skb_pull(skb, sizeof(struct udphdr));
74 /* Check the version. */
75 if ((skb->data[1] & L2TP_VERSION_MASK) != L2TP_VERSION)
80 /* Check the length if it is present. */
81 if (bits & L2TP_LENGTH_BIT) {
82 if ((ptr[0] << 8 | ptr[1]) != skb->len)
87 /* Skip all fields including optional ones. */
88 if (!skb_pull(skb, 6 + (bits & L2TP_SEQUENCE_BIT ? 4 : 0) +
89 (bits & L2TP_LENGTH_BIT ? 2 : 0) +
90 (bits & L2TP_OFFSET_BIT ? 2 : 0)))
93 /* Skip the offset padding if it is present. */
94 if (bits & L2TP_OFFSET_BIT &&
95 !skb_pull(skb, skb->data[-2] << 8 | skb->data[-1]))
98 /* Check the tunnel and the session. */
99 if (unaligned(ptr)->u32 != opt->local)
102 /* Check the sequence if it is present. According to RFC 2661 section
103 * 5.4, the only thing to do is to update opt->sequencing. */
104 opt->sequencing = bits & L2TP_SEQUENCE_BIT;
106 /* Skip PPP address and control if they are present. */
107 if (skb->len >= 2 && skb->data[0] == PPP_ADDR &&
108 skb->data[1] == PPP_CTRL)
111 /* Fix PPP protocol if it is compressed. */
112 if (skb->len >= 1 && skb->data[0] & 1)
113 skb_push(skb, 1)[0] = 0;
115 /* Finally, deliver the packet to PPP channel. */
117 ppp_input(&pppox_sk(sk)->chan, skb);
118 return NET_RX_SUCCESS;
124 static int pppolac_recv(struct sock *sk_udp, struct sk_buff *skb)
127 sk_receive_skb(sk_udp, skb, 0);
131 static struct sk_buff_head delivery_queue;
133 static void pppolac_xmit_core(struct work_struct *delivery_work)
135 mm_segment_t old_fs = get_fs();
139 while ((skb = skb_dequeue(&delivery_queue))) {
140 struct sock *sk_udp = skb->sk;
141 struct kvec iov = {.iov_base = skb->data, .iov_len = skb->len};
142 struct msghdr msg = {
143 .msg_iov = (struct iovec *)&iov,
145 .msg_flags = MSG_NOSIGNAL | MSG_DONTWAIT,
147 sk_udp->sk_prot->sendmsg(NULL, sk_udp, &msg, skb->len);
153 static DECLARE_WORK(delivery_work, pppolac_xmit_core);
155 static int pppolac_xmit(struct ppp_channel *chan, struct sk_buff *skb)
157 struct sock *sk_udp = (struct sock *)chan->private;
158 struct pppolac_opt *opt = &pppox_sk(sk_udp->sk_user_data)->proto.lac;
160 /* Install PPP address and control. */
162 skb->data[0] = PPP_ADDR;
163 skb->data[1] = PPP_CTRL;
165 /* Install L2TP header. */
166 if (opt->sequencing) {
168 skb->data[0] = L2TP_SEQUENCE_BIT;
169 skb->data[6] = opt->sequence >> 8;
170 skb->data[7] = opt->sequence;
178 skb->data[1] = L2TP_VERSION;
179 unaligned(&skb->data[2])->u32 = opt->remote;
181 /* Now send the packet via the delivery queue. */
182 skb_set_owner_w(skb, sk_udp);
183 skb_queue_tail(&delivery_queue, skb);
184 schedule_work(&delivery_work);
188 /******************************************************************************/
190 static struct ppp_channel_ops pppolac_channel_ops = {
191 .start_xmit = pppolac_xmit,
194 static int pppolac_connect(struct socket *sock, struct sockaddr *useraddr,
195 int addrlen, int flags)
197 struct sock *sk = sock->sk;
198 struct pppox_sock *po = pppox_sk(sk);
199 struct sockaddr_pppolac *addr = (struct sockaddr_pppolac *)useraddr;
200 struct socket *sock_udp = NULL;
204 if (addrlen != sizeof(struct sockaddr_pppolac) ||
205 !addr->local.tunnel || !addr->local.session ||
206 !addr->remote.tunnel || !addr->remote.session) {
212 if (sk->sk_state != PPPOX_NONE)
215 sock_udp = sockfd_lookup(addr->udp_socket, &error);
218 sk_udp = sock_udp->sk;
221 /* Remove this check when IPv6 supports UDP encapsulation. */
222 error = -EAFNOSUPPORT;
223 if (sk_udp->sk_family != AF_INET)
225 error = -EPROTONOSUPPORT;
226 if (sk_udp->sk_protocol != IPPROTO_UDP)
228 error = -EDESTADDRREQ;
229 if (sk_udp->sk_state != TCP_ESTABLISHED)
232 if (udp_sk(sk_udp)->encap_type || sk_udp->sk_user_data)
234 if (!sk_udp->sk_bound_dev_if) {
235 struct dst_entry *dst = sk_dst_get(sk_udp);
239 sk_udp->sk_bound_dev_if = dst->dev->ifindex;
243 po->chan.hdrlen = 12;
244 po->chan.private = sk_udp;
245 po->chan.ops = &pppolac_channel_ops;
246 po->chan.mtu = PPP_MTU - 80;
247 po->proto.lac.local = unaligned(&addr->local)->u32;
248 po->proto.lac.remote = unaligned(&addr->remote)->u32;
249 po->proto.lac.backlog_rcv = sk_udp->sk_backlog_rcv;
251 error = ppp_register_channel(&po->chan);
255 sk->sk_state = PPPOX_CONNECTED;
256 udp_sk(sk_udp)->encap_type = UDP_ENCAP_L2TPINUDP;
257 udp_sk(sk_udp)->encap_rcv = pppolac_recv;
258 sk_udp->sk_backlog_rcv = pppolac_recv_core;
259 sk_udp->sk_user_data = sk;
262 release_sock(sk_udp);
264 sockfd_put(sock_udp);
270 static int pppolac_release(struct socket *sock)
272 struct sock *sk = sock->sk;
278 if (sock_flag(sk, SOCK_DEAD)) {
283 if (sk->sk_state != PPPOX_NONE) {
284 struct sock *sk_udp = (struct sock *)pppox_sk(sk)->chan.private;
286 pppox_unbind_sock(sk);
287 udp_sk(sk_udp)->encap_type = 0;
288 udp_sk(sk_udp)->encap_rcv = NULL;
289 sk_udp->sk_backlog_rcv = pppox_sk(sk)->proto.lac.backlog_rcv;
290 sk_udp->sk_user_data = NULL;
291 release_sock(sk_udp);
292 sockfd_put(sk_udp->sk_socket);
302 /******************************************************************************/
304 static struct proto pppolac_proto = {
306 .owner = THIS_MODULE,
307 .obj_size = sizeof(struct pppox_sock),
310 static struct proto_ops pppolac_proto_ops = {
312 .owner = THIS_MODULE,
313 .release = pppolac_release,
314 .bind = sock_no_bind,
315 .connect = pppolac_connect,
316 .socketpair = sock_no_socketpair,
317 .accept = sock_no_accept,
318 .getname = sock_no_getname,
319 .poll = sock_no_poll,
320 .ioctl = pppox_ioctl,
321 .listen = sock_no_listen,
322 .shutdown = sock_no_shutdown,
323 .setsockopt = sock_no_setsockopt,
324 .getsockopt = sock_no_getsockopt,
325 .sendmsg = sock_no_sendmsg,
326 .recvmsg = sock_no_recvmsg,
327 .mmap = sock_no_mmap,
330 static int pppolac_create(struct net *net, struct socket *sock)
334 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppolac_proto);
338 sock_init_data(sock, sk);
339 sock->state = SS_UNCONNECTED;
340 sock->ops = &pppolac_proto_ops;
341 sk->sk_protocol = PX_PROTO_OLAC;
342 sk->sk_state = PPPOX_NONE;
346 /******************************************************************************/
348 static struct pppox_proto pppolac_pppox_proto = {
349 .create = pppolac_create,
350 .owner = THIS_MODULE,
353 static int __init pppolac_init(void)
357 error = proto_register(&pppolac_proto, 0);
361 error = register_pppox_proto(PX_PROTO_OLAC, &pppolac_pppox_proto);
363 proto_unregister(&pppolac_proto);
365 skb_queue_head_init(&delivery_queue);
369 static void __exit pppolac_exit(void)
371 unregister_pppox_proto(PX_PROTO_OLAC);
372 proto_unregister(&pppolac_proto);
375 module_init(pppolac_init);
376 module_exit(pppolac_exit);
378 MODULE_DESCRIPTION("PPP on L2TP Access Concentrator (PPPoLAC)");
379 MODULE_AUTHOR("Chia-chi Yeh <chiachi@android.com>");
380 MODULE_LICENSE("GPL");