[linux.git] / drivers / net / pptp.c

/*
 *  Point-to-Point Tunneling Protocol for Linux
 *
 *	Authors: Dmitry Kozlov <[email protected]>
 *
 *	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/string.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/ppp_channel.h>
#include <linux/ppp_defs.h>
#include <linux/if_pppox.h>
#include <linux/if_ppp.h>
#include <linux/notifier.h>
#include <linux/file.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/version.h>
#include <linux/rcupdate.h>
#include <linux/spinlock.h>

#include <net/sock.h>
#include <net/protocol.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/gre.h>

#include <linux/uaccess.h>

#define PPTP_DRIVER_VERSION "0.8.5"

#define MAX_CALLID 65535

static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
static struct pppox_sock **callid_sock;

static DEFINE_SPINLOCK(chan_lock);

static struct proto pptp_sk_proto __read_mostly;
static const struct ppp_channel_ops pptp_chan_ops;
static const struct proto_ops pptp_ops;

#define PPP_LCP_ECHOREQ 0x09
#define PPP_LCP_ECHOREP 0x0A
#define SC_RCV_BITS	(SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)

#define MISSING_WINDOW 20
#define WRAPPED(curseq, lastseq)\
	((((curseq) & 0xffffff00) == 0) &&\
	(((lastseq) & 0xffffff00) == 0xffffff00))

#define PPTP_GRE_PROTO  0x880B
#define PPTP_GRE_VER    0x1

#define PPTP_GRE_FLAG_C	0x80
#define PPTP_GRE_FLAG_R	0x40
#define PPTP_GRE_FLAG_K	0x20
#define PPTP_GRE_FLAG_S	0x10
#define PPTP_GRE_FLAG_A	0x80

#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)

#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
struct pptp_gre_header {
	u8  flags;
	u8  ver;
	u16 protocol;
	u16 payload_len;
	u16 call_id;
	u32 seq;
	u32 ack;
} __packed;

static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
{
	struct pppox_sock *sock;
	struct pptp_opt *opt;

	rcu_read_lock();
	sock = rcu_dereference(callid_sock[call_id]);
	if (sock) {
		opt = &sock->proto.pptp;
		if (opt->dst_addr.sin_addr.s_addr != s_addr)
			sock = NULL;
		else
			sock_hold(sk_pppox(sock));
	}
	rcu_read_unlock();

	return sock;
}

static int lookup_chan_dst(u16 call_id, __be32 d_addr)
{
	struct pppox_sock *sock;
	struct pptp_opt *opt;
	int i;

	rcu_read_lock();
	for (i = find_next_bit(callid_bitmap, MAX_CALLID, 1); i < MAX_CALLID;
	     i = find_next_bit(callid_bitmap, MAX_CALLID, i + 1)) {
		sock = rcu_dereference(callid_sock[i]);
		if (!sock)
			continue;
		opt = &sock->proto.pptp;
		if (opt->dst_addr.call_id == call_id &&
			  opt->dst_addr.sin_addr.s_addr == d_addr)
			break;
	}
	rcu_read_unlock();

	return i < MAX_CALLID;
}

static int add_chan(struct pppox_sock *sock)
{
	static int call_id;

	spin_lock(&chan_lock);
	if (!sock->proto.pptp.src_addr.call_id)	{
		call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
		if (call_id == MAX_CALLID) {
			call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
			if (call_id == MAX_CALLID)
				goto out_err;
		}
		sock->proto.pptp.src_addr.call_id = call_id;
	} else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap))
		goto out_err;

	set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
	rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], sock);
	spin_unlock(&chan_lock);

	return 0;

out_err:
	spin_unlock(&chan_lock);
	return -1;
}

static void del_chan(struct pppox_sock *sock)
{
	spin_lock(&chan_lock);
	clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
	rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
	spin_unlock(&chan_lock);
	synchronize_rcu();
}

static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
{
	struct sock *sk = (struct sock *) chan->private;
	struct pppox_sock *po = pppox_sk(sk);
	struct pptp_opt *opt = &po->proto.pptp;
	struct pptp_gre_header *hdr;
	unsigned int header_len = sizeof(*hdr);
	int islcp;
	int len;
	unsigned char *data;
	__u32 seq_recv;


	struct rtable *rt;
	struct net_device *tdev;
	struct iphdr  *iph;
	int    max_headroom;

	if (sk_pppox(po)->sk_state & PPPOX_DEAD)
		goto tx_error;

	rt = ip_route_output_ports(&init_net, NULL,
				   opt->dst_addr.sin_addr.s_addr,
				   opt->src_addr.sin_addr.s_addr,
				   0, 0, IPPROTO_GRE,
				   RT_TOS(0), 0);
	if (IS_ERR(rt))
		goto tx_error;

	tdev = rt->dst.dev;

	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;

	if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
		if (!new_skb) {
			ip_rt_put(rt);
			goto tx_error;
		}
		if (skb->sk)
			skb_set_owner_w(new_skb, skb->sk);
		kfree_skb(skb);
		skb = new_skb;
	}

	data = skb->data;
	islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;

	/* compress protocol field */
	if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
		skb_pull(skb, 1);

	/* Put in the address/control bytes if necessary */
	if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
		data = skb_push(skb, 2);
		data[0] = PPP_ALLSTATIONS;
		data[1] = PPP_UI;
	}

	len = skb->len;

	seq_recv = opt->seq_recv;

	if (opt->ack_sent == seq_recv)
		header_len -= sizeof(hdr->ack);

	/* Push down and install GRE header */
	skb_push(skb, header_len);
	hdr = (struct pptp_gre_header *)(skb->data);

	hdr->flags       = PPTP_GRE_FLAG_K;
	hdr->ver         = PPTP_GRE_VER;
	hdr->protocol    = htons(PPTP_GRE_PROTO);
	hdr->call_id     = htons(opt->dst_addr.call_id);

	hdr->flags      |= PPTP_GRE_FLAG_S;
	hdr->seq         = htonl(++opt->seq_sent);
	if (opt->ack_sent != seq_recv)	{
		/* send ack with this message */
		hdr->ver |= PPTP_GRE_FLAG_A;
		hdr->ack  = htonl(seq_recv);
		opt->ack_sent = seq_recv;
	}
	hdr->payload_len = htons(len);

	/*	Push down and install the IP header. */

	skb_reset_transport_header(skb);
	skb_push(skb, sizeof(*iph));
	skb_reset_network_header(skb);
	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);

	iph =	ip_hdr(skb);
	iph->version =	4;
	iph->ihl =	sizeof(struct iphdr) >> 2;
	if (ip_dont_fragment(sk, &rt->dst))
		iph->frag_off	=	htons(IP_DF);
	else
		iph->frag_off	=	0;
	iph->protocol = IPPROTO_GRE;
	iph->tos      = 0;
	iph->daddr    = rt->rt_dst;
	iph->saddr    = rt->rt_src;
	iph->ttl      = ip4_dst_hoplimit(&rt->dst);
	iph->tot_len  = htons(skb->len);

	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);

	nf_reset(skb);

	skb->ip_summed = CHECKSUM_NONE;
	ip_select_ident(iph, &rt->dst, NULL);
	ip_send_check(iph);

	ip_local_out(skb);

tx_error:
	return 1;
}

static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
{
	struct pppox_sock *po = pppox_sk(sk);
	struct pptp_opt *opt = &po->proto.pptp;
	int headersize, payload_len, seq;
	__u8 *payload;
	struct pptp_gre_header *header;

	if (!(sk->sk_state & PPPOX_CONNECTED)) {
		if (sock_queue_rcv_skb(sk, skb))
			goto drop;
		return NET_RX_SUCCESS;
	}

	header = (struct pptp_gre_header *)(skb->data);

	/* test if acknowledgement present */
	if (PPTP_GRE_IS_A(header->ver)) {
		__u32 ack = (PPTP_GRE_IS_S(header->flags)) ?
				header->ack : header->seq; /* ack in different place if S = 0 */

		ack = ntohl(ack);

		if (ack > opt->ack_recv)
			opt->ack_recv = ack;
		/* also handle sequence number wrap-around  */
		if (WRAPPED(ack, opt->ack_recv))
			opt->ack_recv = ack;
	}

	/* test if payload present */
	if (!PPTP_GRE_IS_S(header->flags))
		goto drop;

	headersize  = sizeof(*header);
	payload_len = ntohs(header->payload_len);
	seq         = ntohl(header->seq);

	/* no ack present? */
	if (!PPTP_GRE_IS_A(header->ver))
		headersize -= sizeof(header->ack);
	/* check for incomplete packet (length smaller than expected) */
	if (skb->len - headersize < payload_len)
		goto drop;

	payload = skb->data + headersize;
	/* check for expected sequence number */
	if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
		if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
				(PPP_PROTOCOL(payload) == PPP_LCP) &&
				((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
			goto allow_packet;
	} else {
		opt->seq_recv = seq;
allow_packet:
		skb_pull(skb, headersize);

		if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
			/* chop off address/control */
			if (skb->len < 3)
				goto drop;
			skb_pull(skb, 2);
		}

		if ((*skb->data) & 1) {
			/* protocol is compressed */
			skb_push(skb, 1)[0] = 0;
		}

		skb->ip_summed = CHECKSUM_NONE;
		skb_set_network_header(skb, skb->head-skb->data);
		ppp_input(&po->chan, skb);

		return NET_RX_SUCCESS;
	}
drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

static int pptp_rcv(struct sk_buff *skb)
{
	struct pppox_sock *po;
	struct pptp_gre_header *header;
	struct iphdr *iph;

	if (skb->pkt_type != PACKET_HOST)
		goto drop;

	if (!pskb_may_pull(skb, 12))
		goto drop;

	iph = ip_hdr(skb);

	header = (struct pptp_gre_header *)skb->data;

	if (ntohs(header->protocol) != PPTP_GRE_PROTO || /* PPTP-GRE protocol for PPTP */
		PPTP_GRE_IS_C(header->flags) ||                /* flag C should be clear */
		PPTP_GRE_IS_R(header->flags) ||                /* flag R should be clear */
		!PPTP_GRE_IS_K(header->flags) ||               /* flag K should be set */
		(header->flags&0xF) != 0)                      /* routing and recursion ctrl = 0 */
		/* if invalid, discard this packet */
		goto drop;

	po = lookup_chan(htons(header->call_id), iph->saddr);
	if (po) {
		skb_dst_drop(skb);
		nf_reset(skb);
		return sk_receive_skb(sk_pppox(po), skb, 0);
	}
drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
	int sockaddr_len)
{
	struct sock *sk = sock->sk;
	struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
	struct pppox_sock *po = pppox_sk(sk);
	struct pptp_opt *opt = &po->proto.pptp;
	int error = 0;

	lock_sock(sk);

	opt->src_addr = sp->sa_addr.pptp;
	if (add_chan(po)) {
		release_sock(sk);
		error = -EBUSY;
	}

	release_sock(sk);
	return error;
}

static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
	int sockaddr_len, int flags)
{
	struct sock *sk = sock->sk;
	struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
	struct pppox_sock *po = pppox_sk(sk);
	struct pptp_opt *opt = &po->proto.pptp;
	struct rtable *rt;
	int error = 0;

	if (sp->sa_protocol != PX_PROTO_PPTP)
		return -EINVAL;

	if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
		return -EALREADY;

	lock_sock(sk);
	/* Check for already bound sockets */
	if (sk->sk_state & PPPOX_CONNECTED) {
		error = -EBUSY;
		goto end;
	}

	/* Check for already disconnected sockets, on attempts to disconnect */
	if (sk->sk_state & PPPOX_DEAD) {
		error = -EALREADY;
		goto end;
	}

	if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
		error = -EINVAL;
		goto end;
	}

	po->chan.private = sk;
	po->chan.ops = &pptp_chan_ops;

	rt = ip_route_output_ports(&init_net, sk,
				   opt->dst_addr.sin_addr.s_addr,
				   opt->src_addr.sin_addr.s_addr,
				   0, 0,
				   IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
	if (IS_ERR(rt)) {
		error = -EHOSTUNREACH;
		goto end;
	}
	sk_setup_caps(sk, &rt->dst);

	po->chan.mtu = dst_mtu(&rt->dst);
	if (!po->chan.mtu)
		po->chan.mtu = PPP_MTU;
	ip_rt_put(rt);
	po->chan.mtu -= PPTP_HEADER_OVERHEAD;

	po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
	error = ppp_register_channel(&po->chan);
	if (error) {
		pr_err("PPTP: failed to register PPP channel (%d)\n", error);
		goto end;
	}

	opt->dst_addr = sp->sa_addr.pptp;
	sk->sk_state = PPPOX_CONNECTED;

 end:
	release_sock(sk);
	return error;
}

static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
	int *usockaddr_len, int peer)
{
	int len = sizeof(struct sockaddr_pppox);
	struct sockaddr_pppox sp;

	sp.sa_family	  = AF_PPPOX;
	sp.sa_protocol  = PX_PROTO_PPTP;
	sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;

	memcpy(uaddr, &sp, len);

	*usockaddr_len = len;

	return 0;
}

static int pptp_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct pppox_sock *po;
	struct pptp_opt *opt;
	int error = 0;

	if (!sk)
		return 0;

	lock_sock(sk);

	if (sock_flag(sk, SOCK_DEAD)) {
		release_sock(sk);
		return -EBADF;
	}

	po = pppox_sk(sk);
	opt = &po->proto.pptp;
	del_chan(po);

	pppox_unbind_sock(sk);
	sk->sk_state = PPPOX_DEAD;

	sock_orphan(sk);
	sock->sk = NULL;

	release_sock(sk);
	sock_put(sk);

	return error;
}

static void pptp_sock_destruct(struct sock *sk)
{
	if (!(sk->sk_state & PPPOX_DEAD)) {
		del_chan(pppox_sk(sk));
		pppox_unbind_sock(sk);
	}
	skb_queue_purge(&sk->sk_receive_queue);
}

static int pptp_create(struct net *net, struct socket *sock)
{
	int error = -ENOMEM;
	struct sock *sk;
	struct pppox_sock *po;
	struct pptp_opt *opt;

	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto);
	if (!sk)
		goto out;

	sock_init_data(sock, sk);

	sock->state = SS_UNCONNECTED;
	sock->ops   = &pptp_ops;

	sk->sk_backlog_rcv = pptp_rcv_core;
	sk->sk_state       = PPPOX_NONE;
	sk->sk_type        = SOCK_STREAM;
	sk->sk_family      = PF_PPPOX;
	sk->sk_protocol    = PX_PROTO_PPTP;
	sk->sk_destruct    = pptp_sock_destruct;

	po = pppox_sk(sk);
	opt = &po->proto.pptp;

	opt->seq_sent = 0; opt->seq_recv = 0;
	opt->ack_recv = 0; opt->ack_sent = 0;

	error = 0;
out:
	return error;
}

static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
	unsigned long arg)
{
	struct sock *sk = (struct sock *) chan->private;
	struct pppox_sock *po = pppox_sk(sk);
	struct pptp_opt *opt = &po->proto.pptp;
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	int err, val;

	err = -EFAULT;
	switch (cmd) {
	case PPPIOCGFLAGS:
		val = opt->ppp_flags;
		if (put_user(val, p))
			break;
		err = 0;
		break;
	case PPPIOCSFLAGS:
		if (get_user(val, p))
			break;
		opt->ppp_flags = val & ~SC_RCV_BITS;
		err = 0;
		break;
	default:
		err = -ENOTTY;
	}

	return err;
}

static const struct ppp_channel_ops pptp_chan_ops = {
	.start_xmit = pptp_xmit,
	.ioctl      = pptp_ppp_ioctl,
};

static struct proto pptp_sk_proto __read_mostly = {
	.name     = "PPTP",
	.owner    = THIS_MODULE,
	.obj_size = sizeof(struct pppox_sock),
};

static const struct proto_ops pptp_ops = {
	.family     = AF_PPPOX,
	.owner      = THIS_MODULE,
	.release    = pptp_release,
	.bind       = pptp_bind,
	.connect    = pptp_connect,
	.socketpair = sock_no_socketpair,
	.accept     = sock_no_accept,
	.getname    = pptp_getname,
	.poll       = sock_no_poll,
	.listen     = sock_no_listen,
	.shutdown   = sock_no_shutdown,
	.setsockopt = sock_no_setsockopt,
	.getsockopt = sock_no_getsockopt,
	.sendmsg    = sock_no_sendmsg,
	.recvmsg    = sock_no_recvmsg,
	.mmap       = sock_no_mmap,
	.ioctl      = pppox_ioctl,
};

static const struct pppox_proto pppox_pptp_proto = {
	.create = pptp_create,
	.owner  = THIS_MODULE,
};

static const struct gre_protocol gre_pptp_protocol = {
	.handler = pptp_rcv,
};

static int __init pptp_init_module(void)
{
	int err = 0;
	pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");

	callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
	if (!callid_sock) {
		pr_err("PPTP: cann't allocate memory\n");
		return -ENOMEM;
	}

	err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	if (err) {
		pr_err("PPTP: can't add gre protocol\n");
		goto out_mem_free;
	}

	err = proto_register(&pptp_sk_proto, 0);
	if (err) {
		pr_err("PPTP: can't register sk_proto\n");
		goto out_gre_del_protocol;
	}

	err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
	if (err) {
		pr_err("PPTP: can't register pppox_proto\n");
		goto out_unregister_sk_proto;
	}

	return 0;

out_unregister_sk_proto:
	proto_unregister(&pptp_sk_proto);
out_gre_del_protocol:
	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
out_mem_free:
	vfree(callid_sock);

	return err;
}

static void __exit pptp_exit_module(void)
{
	unregister_pppox_proto(PX_PROTO_PPTP);
	proto_unregister(&pptp_sk_proto);
	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	vfree(callid_sock);
}

module_init(pptp_init_module);
module_exit(pptp_exit_module);

MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
MODULE_AUTHOR("D. Kozlov ([email protected])");
MODULE_LICENSE("GPL");
Commit	Line	Data
00959ade DK	1	/*
	2	* Point-to-Point Tunneling Protocol for Linux
	3	*
	4	* Authors: Dmitry Kozlov <[email protected]>
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*
	11	*/
	12
	13	#include <linux/string.h>
	14	#include <linux/module.h>
	15	#include <linux/kernel.h>
	16	#include <linux/slab.h>
	17	#include <linux/errno.h>
	18	#include <linux/netdevice.h>
	19	#include <linux/net.h>
	20	#include <linux/skbuff.h>
	21	#include <linux/vmalloc.h>
	22	#include <linux/init.h>
	23	#include <linux/ppp_channel.h>
	24	#include <linux/ppp_defs.h>
	25	#include <linux/if_pppox.h>
	26	#include <linux/if_ppp.h>
	27	#include <linux/notifier.h>
	28	#include <linux/file.h>
	29	#include <linux/in.h>
	30	#include <linux/ip.h>
	31	#include <linux/netfilter.h>
	32	#include <linux/netfilter_ipv4.h>
	33	#include <linux/version.h>
	34	#include <linux/rcupdate.h>
	35	#include <linux/spinlock.h>
	36
	37	#include <net/sock.h>
	38	#include <net/protocol.h>
	39	#include <net/ip.h>
	40	#include <net/icmp.h>
	41	#include <net/route.h>
	42	#include <net/gre.h>
	43
	44	#include <linux/uaccess.h>
	45
	46	#define PPTP_DRIVER_VERSION "0.8.5"
	47
	48	#define MAX_CALLID 65535
	49
	50	static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
	51	static struct pppox_sock **callid_sock;
	52
	53	static DEFINE_SPINLOCK(chan_lock);
	54
	55	static struct proto pptp_sk_proto __read_mostly;
756e64a0	56	static const struct ppp_channel_ops pptp_chan_ops;
00959ade DK	57	static const struct proto_ops pptp_ops;
	58
	59	#define PPP_LCP_ECHOREQ 0x09
	60	#define PPP_LCP_ECHOREP 0x0A
	61	#define SC_RCV_BITS (SC_RCV_B7_1\|SC_RCV_B7_0\|SC_RCV_ODDP\|SC_RCV_EVNP)
	62
	63	#define MISSING_WINDOW 20
	64	#define WRAPPED(curseq, lastseq)\
	65	((((curseq) & 0xffffff00) == 0) &&\
	66	(((lastseq) & 0xffffff00) == 0xffffff00))
	67
	68	#define PPTP_GRE_PROTO 0x880B
	69	#define PPTP_GRE_VER 0x1
	70
	71	#define PPTP_GRE_FLAG_C 0x80
	72	#define PPTP_GRE_FLAG_R 0x40
	73	#define PPTP_GRE_FLAG_K 0x20
	74	#define PPTP_GRE_FLAG_S 0x10
	75	#define PPTP_GRE_FLAG_A 0x80
	76
	77	#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
	78	#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
	79	#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
	80	#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
	81	#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)
	82
	83	#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
	84	struct pptp_gre_header {
	85	u8 flags;
	86	u8 ver;
	87	u16 protocol;
	88	u16 payload_len;
	89	u16 call_id;
	90	u32 seq;
	91	u32 ack;
	92	} __packed;
	93
	94	static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
	95	{
	96	struct pppox_sock *sock;
	97	struct pptp_opt *opt;
	98
	99	rcu_read_lock();
	100	sock = rcu_dereference(callid_sock[call_id]);
	101	if (sock) {
	102	opt = &sock->proto.pptp;
	103	if (opt->dst_addr.sin_addr.s_addr != s_addr)
	104	sock = NULL;
	105	else
	106	sock_hold(sk_pppox(sock));
	107	}
	108	rcu_read_unlock();
	109
	110	return sock;
	111	}
	112
	113	static int lookup_chan_dst(u16 call_id, __be32 d_addr)
	114	{
	115	struct pppox_sock *sock;
	116	struct pptp_opt *opt;
	117	int i;
	118
	119	rcu_read_lock();
	120	for (i = find_next_bit(callid_bitmap, MAX_CALLID, 1); i < MAX_CALLID;
121	i = find_next_bit(callid_bitmap, MAX_CALLID, i + 1)) {
122	sock = rcu_dereference(callid_sock[i]);
123	if (!sock)
124	continue;
125	opt = &sock->proto.pptp;
126	if (opt->dst_addr.call_id == call_id &&
127	opt->dst_addr.sin_addr.s_addr == d_addr)
128	break;
129	}
130	rcu_read_unlock();
131
132	return i < MAX_CALLID;
133	}
134
135	static int add_chan(struct pppox_sock *sock)
136	{
137	static int call_id;
138
139	spin_lock(&chan_lock);
140	if (!sock->proto.pptp.src_addr.call_id) {
141	call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
142	if (call_id == MAX_CALLID) {
143	call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
144	if (call_id == MAX_CALLID)
145	goto out_err;
146	}
147	sock->proto.pptp.src_addr.call_id = call_id;
148	} else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap))
149	goto out_err;
150
151	set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
152	rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], sock);
153	spin_unlock(&chan_lock);
154
155	return 0;
156
157	out_err:
158	spin_unlock(&chan_lock);
159	return -1;
160	}
161
162	static void del_chan(struct pppox_sock *sock)
163	{
164	spin_lock(&chan_lock);
165	clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
166	rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
167	spin_unlock(&chan_lock);
168	synchronize_rcu();
169	}
170
171	static int pptp_xmit(struct ppp_channel chan, struct sk_buff skb)
172	{
173	struct sock sk = (struct sock ) chan->private;
174	struct pppox_sock *po = pppox_sk(sk);
175	struct pptp_opt *opt = &po->proto.pptp;
176	struct pptp_gre_header *hdr;
177	unsigned int header_len = sizeof(*hdr);
00959ade DK	178	int islcp;
	179	int len;
	180	unsigned char *data;
	181	__u32 seq_recv;
	182
	183
	184	struct rtable *rt;
	185	struct net_device *tdev;
	186	struct iphdr *iph;
	187	int max_headroom;
	188
	189	if (sk_pppox(po)->sk_state & PPPOX_DEAD)
	190	goto tx_error;
	191
78fbfd8a DM	192	rt = ip_route_output_ports(&init_net, NULL,
	193	opt->dst_addr.sin_addr.s_addr,
	194	opt->src_addr.sin_addr.s_addr,
	195	0, 0, IPPROTO_GRE,
	196	RT_TOS(0), 0);
	197	if (IS_ERR(rt))
	198	goto tx_error;
	199
00959ade DK	200	tdev = rt->dst.dev;
	201
	202	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(iph) + sizeof(hdr) + 2;
	203
	204	if (skb_headroom(skb) < max_headroom \|\| skb_cloned(skb) \|\| skb_shared(skb)) {
	205	struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
	206	if (!new_skb) {
	207	ip_rt_put(rt);
	208	goto tx_error;
	209	}
	210	if (skb->sk)
	211	skb_set_owner_w(new_skb, skb->sk);
	212	kfree_skb(skb);
	213	skb = new_skb;
	214	}
	215
	216	data = skb->data;
	217	islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
	218
	219	/* compress protocol field */
	220	if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
	221	skb_pull(skb, 1);
	222
	223	/* Put in the address/control bytes if necessary */
	224	if ((opt->ppp_flags & SC_COMP_AC) == 0 \|\| islcp) {
	225	data = skb_push(skb, 2);
	226	data[0] = PPP_ALLSTATIONS;
	227	data[1] = PPP_UI;
	228	}
	229
	230	len = skb->len;
	231
	232	seq_recv = opt->seq_recv;
	233
	234	if (opt->ack_sent == seq_recv)
	235	header_len -= sizeof(hdr->ack);
	236
	237	/* Push down and install GRE header */
	238	skb_push(skb, header_len);
	239	hdr = (struct pptp_gre_header *)(skb->data);
	240
	241	hdr->flags = PPTP_GRE_FLAG_K;
	242	hdr->ver = PPTP_GRE_VER;
	243	hdr->protocol = htons(PPTP_GRE_PROTO);
	244	hdr->call_id = htons(opt->dst_addr.call_id);
	245
	246	hdr->flags \|= PPTP_GRE_FLAG_S;
	247	hdr->seq = htonl(++opt->seq_sent);
	248	if (opt->ack_sent != seq_recv) {
	249	/* send ack with this message */
	250	hdr->ver \|= PPTP_GRE_FLAG_A;
	251	hdr->ack = htonl(seq_recv);
	252	opt->ack_sent = seq_recv;
	253	}
	254	hdr->payload_len = htons(len);
	255
	256	/* Push down and install the IP header. */
	257
	258	skb_reset_transport_header(skb);
	259	skb_push(skb, sizeof(*iph));
	260	skb_reset_network_header(skb);
	261	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
	262	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE \| IPSKB_XFRM_TRANSFORMED \| IPSKB_REROUTED);
	263
264	iph = ip_hdr(skb);
265	iph->version = 4;
266	iph->ihl = sizeof(struct iphdr) >> 2;
267	if (ip_dont_fragment(sk, &rt->dst))
268	iph->frag_off = htons(IP_DF);
269	else
270	iph->frag_off = 0;
271	iph->protocol = IPPROTO_GRE;
272	iph->tos = 0;
273	iph->daddr = rt->rt_dst;
274	iph->saddr = rt->rt_src;
323e126f	275	iph->ttl = ip4_dst_hoplimit(&rt->dst);
00959ade DK	276	iph->tot_len = htons(skb->len);
	277
	278	skb_dst_drop(skb);
	279	skb_dst_set(skb, &rt->dst);
	280
	281	nf_reset(skb);
	282
	283	skb->ip_summed = CHECKSUM_NONE;
	284	ip_select_ident(iph, &rt->dst, NULL);
	285	ip_send_check(iph);
	286
	287	ip_local_out(skb);
	288
	289	tx_error:
	290	return 1;
	291	}
	292
	293	static int pptp_rcv_core(struct sock sk, struct sk_buff skb)
	294	{
	295	struct pppox_sock *po = pppox_sk(sk);
	296	struct pptp_opt *opt = &po->proto.pptp;
	297	int headersize, payload_len, seq;
	298	__u8 *payload;
	299	struct pptp_gre_header *header;
	300
	301	if (!(sk->sk_state & PPPOX_CONNECTED)) {
	302	if (sock_queue_rcv_skb(sk, skb))
	303	goto drop;
	304	return NET_RX_SUCCESS;
	305	}
	306
	307	header = (struct pptp_gre_header *)(skb->data);
	308
	309	/* test if acknowledgement present */
	310	if (PPTP_GRE_IS_A(header->ver)) {
	311	__u32 ack = (PPTP_GRE_IS_S(header->flags)) ?
	312	header->ack : header->seq; /* ack in different place if S = 0 */
	313
	314	ack = ntohl(ack);
	315
	316	if (ack > opt->ack_recv)
	317	opt->ack_recv = ack;
	318	/* also handle sequence number wrap-around */
	319	if (WRAPPED(ack, opt->ack_recv))
	320	opt->ack_recv = ack;
	321	}
	322
	323	/* test if payload present */
	324	if (!PPTP_GRE_IS_S(header->flags))
	325	goto drop;
	326
	327	headersize = sizeof(*header);
	328	payload_len = ntohs(header->payload_len);
	329	seq = ntohl(header->seq);
	330
	331	/* no ack present? */
	332	if (!PPTP_GRE_IS_A(header->ver))
	333	headersize -= sizeof(header->ack);
	334	/* check for incomplete packet (length smaller than expected) */
	335	if (skb->len - headersize < payload_len)
	336	goto drop;
	337
	338	payload = skb->data + headersize;
	339	/* check for expected sequence number */
340	if (seq < opt->seq_recv + 1 \|\| WRAPPED(opt->seq_recv, seq)) {
341	if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
342	(PPP_PROTOCOL(payload) == PPP_LCP) &&
343	((payload[4] == PPP_LCP_ECHOREQ) \|\| (payload[4] == PPP_LCP_ECHOREP)))
344	goto allow_packet;
345	} else {
346	opt->seq_recv = seq;
347	allow_packet:
348	skb_pull(skb, headersize);
349
350	if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
351	/* chop off address/control */
352	if (skb->len < 3)
353	goto drop;
354	skb_pull(skb, 2);
355	}
356
357	if ((*skb->data) & 1) {
358	/* protocol is compressed */
359	skb_push(skb, 1)[0] = 0;
360	}
361
362	skb->ip_summed = CHECKSUM_NONE;
363	skb_set_network_header(skb, skb->head-skb->data);
364	ppp_input(&po->chan, skb);
365
366	return NET_RX_SUCCESS;
367	}
368	drop:
369	kfree_skb(skb);
370	return NET_RX_DROP;
371	}
372
373	static int pptp_rcv(struct sk_buff *skb)
374	{
375	struct pppox_sock *po;
376	struct pptp_gre_header *header;
377	struct iphdr *iph;
378
379	if (skb->pkt_type != PACKET_HOST)
380	goto drop;
381
382	if (!pskb_may_pull(skb, 12))
383	goto drop;
384
385	iph = ip_hdr(skb);
386
387	header = (struct pptp_gre_header *)skb->data;
388
389	if (ntohs(header->protocol) != PPTP_GRE_PROTO \|\| /* PPTP-GRE protocol for PPTP */
390	PPTP_GRE_IS_C(header->flags) \|\| /* flag C should be clear */
391	PPTP_GRE_IS_R(header->flags) \|\| /* flag R should be clear */
392	!PPTP_GRE_IS_K(header->flags) \|\| /* flag K should be set */
393	(header->flags&0xF) != 0) /* routing and recursion ctrl = 0 */
394	/* if invalid, discard this packet */
395	goto drop;
396
397	po = lookup_chan(htons(header->call_id), iph->saddr);
398	if (po) {
399	skb_dst_drop(skb);
400	nf_reset(skb);
401	return sk_receive_skb(sk_pppox(po), skb, 0);
402	}
403	drop:
404	kfree_skb(skb);
405	return NET_RX_DROP;
406	}
407
408	static int pptp_bind(struct socket sock, struct sockaddr uservaddr,
409	int sockaddr_len)
410	{
411	struct sock *sk = sock->sk;
412	struct sockaddr_pppox sp = (struct sockaddr_pppox ) uservaddr;
413	struct pppox_sock *po = pppox_sk(sk);
414	struct pptp_opt *opt = &po->proto.pptp;
415	int error = 0;
416
417	lock_sock(sk);
418
419	opt->src_addr = sp->sa_addr.pptp;
420	if (add_chan(po)) {
421	release_sock(sk);
422	error = -EBUSY;
423	}
424
425	release_sock(sk);
426	return error;
427	}
428
429	static int pptp_connect(struct socket sock, struct sockaddr uservaddr,
430	int sockaddr_len, int flags)
431	{
432	struct sock *sk = sock->sk;
433	struct sockaddr_pppox sp = (struct sockaddr_pppox ) uservaddr;
434	struct pppox_sock *po = pppox_sk(sk);
435	struct pptp_opt *opt = &po->proto.pptp;
436	struct rtable *rt;
437	int error = 0;
438
439	if (sp->sa_protocol != PX_PROTO_PPTP)
440	return -EINVAL;
441
442	if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
443	return -EALREADY;
444
445	lock_sock(sk);
446	/* Check for already bound sockets */
447	if (sk->sk_state & PPPOX_CONNECTED) {
448	error = -EBUSY;
449	goto end;
450	}
451
452	/* Check for already disconnected sockets, on attempts to disconnect */
453	if (sk->sk_state & PPPOX_DEAD) {
454	error = -EALREADY;
455	goto end;
456	}
457
458	if (!opt->src_addr.sin_addr.s_addr \|\| !sp->sa_addr.pptp.sin_addr.s_addr) {
459	error = -EINVAL;
460	goto end;
461	}
462
463	po->chan.private = sk;
464	po->chan.ops = &pptp_chan_ops;
465
78fbfd8a DM	466	rt = ip_route_output_ports(&init_net, sk,
	467	opt->dst_addr.sin_addr.s_addr,
	468	opt->src_addr.sin_addr.s_addr,
	469	0, 0,
	470	IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
	471	if (IS_ERR(rt)) {
	472	error = -EHOSTUNREACH;
	473	goto end;
00959ade	474	}
78fbfd8a DM	475	sk_setup_caps(sk, &rt->dst);
78fbfd8a DM	476
00959ade DK	477	po->chan.mtu = dst_mtu(&rt->dst);
	478	if (!po->chan.mtu)
	479	po->chan.mtu = PPP_MTU;
	480	ip_rt_put(rt);
	481	po->chan.mtu -= PPTP_HEADER_OVERHEAD;
	482
	483	po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
	484	error = ppp_register_channel(&po->chan);
	485	if (error) {
	486	pr_err("PPTP: failed to register PPP channel (%d)\n", error);
	487	goto end;
	488	}
	489
	490	opt->dst_addr = sp->sa_addr.pptp;
	491	sk->sk_state = PPPOX_CONNECTED;
	492
	493	end:
	494	release_sock(sk);
	495	return error;
	496	}
	497
	498	static int pptp_getname(struct socket sock, struct sockaddr uaddr,
	499	int *usockaddr_len, int peer)
	500	{
	501	int len = sizeof(struct sockaddr_pppox);
	502	struct sockaddr_pppox sp;
	503
	504	sp.sa_family = AF_PPPOX;
	505	sp.sa_protocol = PX_PROTO_PPTP;
	506	sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
	507
	508	memcpy(uaddr, &sp, len);
	509
	510	*usockaddr_len = len;
	511
	512	return 0;
	513	}
	514
	515	static int pptp_release(struct socket *sock)
	516	{
	517	struct sock *sk = sock->sk;
	518	struct pppox_sock *po;
	519	struct pptp_opt *opt;
	520	int error = 0;
	521
	522	if (!sk)
	523	return 0;
	524
	525	lock_sock(sk);
	526
	527	if (sock_flag(sk, SOCK_DEAD)) {
	528	release_sock(sk);
	529	return -EBADF;
	530	}
	531
	532	po = pppox_sk(sk);
	533	opt = &po->proto.pptp;
	534	del_chan(po);
	535
	536	pppox_unbind_sock(sk);
	537	sk->sk_state = PPPOX_DEAD;
	538
	539	sock_orphan(sk);
	540	sock->sk = NULL;
541
542	release_sock(sk);
543	sock_put(sk);
544
545	return error;
546	}
547
548	static void pptp_sock_destruct(struct sock *sk)
549	{
550	if (!(sk->sk_state & PPPOX_DEAD)) {
551	del_chan(pppox_sk(sk));
552	pppox_unbind_sock(sk);
553	}
554	skb_queue_purge(&sk->sk_receive_queue);
555	}
556
557	static int pptp_create(struct net net, struct socket sock)
558	{
559	int error = -ENOMEM;
560	struct sock *sk;
561	struct pppox_sock *po;
562	struct pptp_opt *opt;
563
564	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto);
565	if (!sk)
566	goto out;
567
568	sock_init_data(sock, sk);
569
570	sock->state = SS_UNCONNECTED;
571	sock->ops = &pptp_ops;
572
573	sk->sk_backlog_rcv = pptp_rcv_core;
574	sk->sk_state = PPPOX_NONE;
575	sk->sk_type = SOCK_STREAM;
576	sk->sk_family = PF_PPPOX;
577	sk->sk_protocol = PX_PROTO_PPTP;
578	sk->sk_destruct = pptp_sock_destruct;
579
580	po = pppox_sk(sk);
581	opt = &po->proto.pptp;
582
583	opt->seq_sent = 0; opt->seq_recv = 0;
584	opt->ack_recv = 0; opt->ack_sent = 0;
585
586	error = 0;
587	out:
588	return error;
589	}
590
591	static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
592	unsigned long arg)
593	{
594	struct sock sk = (struct sock ) chan->private;
595	struct pppox_sock *po = pppox_sk(sk);
596	struct pptp_opt *opt = &po->proto.pptp;
597	void __user argp = (void __user )arg;
598	int __user *p = argp;
599	int err, val;
600
601	err = -EFAULT;
602	switch (cmd) {
603	case PPPIOCGFLAGS:
604	val = opt->ppp_flags;
605	if (put_user(val, p))
606	break;
607	err = 0;
608	break;
609	case PPPIOCSFLAGS:
610	if (get_user(val, p))
611	break;
612	opt->ppp_flags = val & ~SC_RCV_BITS;
613	err = 0;
614	break;
615	default:
616	err = -ENOTTY;
617	}
618
619	return err;
620	}
621
756e64a0	622	static const struct ppp_channel_ops pptp_chan_ops = {
00959ade DK	623	.start_xmit = pptp_xmit,
	624	.ioctl = pptp_ppp_ioctl,
	625	};
	626
	627	static struct proto pptp_sk_proto __read_mostly = {
	628	.name = "PPTP",
	629	.owner = THIS_MODULE,
	630	.obj_size = sizeof(struct pppox_sock),
	631	};
	632
	633	static const struct proto_ops pptp_ops = {
	634	.family = AF_PPPOX,
	635	.owner = THIS_MODULE,
	636	.release = pptp_release,
	637	.bind = pptp_bind,
	638	.connect = pptp_connect,
	639	.socketpair = sock_no_socketpair,
	640	.accept = sock_no_accept,
	641	.getname = pptp_getname,
	642	.poll = sock_no_poll,
	643	.listen = sock_no_listen,
	644	.shutdown = sock_no_shutdown,
	645	.setsockopt = sock_no_setsockopt,
	646	.getsockopt = sock_no_getsockopt,
	647	.sendmsg = sock_no_sendmsg,
	648	.recvmsg = sock_no_recvmsg,
	649	.mmap = sock_no_mmap,
	650	.ioctl = pppox_ioctl,
	651	};
	652
756e64a0	653	static const struct pppox_proto pppox_pptp_proto = {
00959ade DK	654	.create = pptp_create,
	655	.owner = THIS_MODULE,
	656	};
	657
756e64a0	658	static const struct gre_protocol gre_pptp_protocol = {
00959ade DK	659	.handler = pptp_rcv,
	660	};
	661
	662	static int __init pptp_init_module(void)
	663	{
	664	int err = 0;
	665	pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
	666
89bf67f1	667	callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
00959ade DK	668	if (!callid_sock) {
	669	pr_err("PPTP: cann't allocate memory\n");
	670	return -ENOMEM;
	671	}
	672
	673	err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	674	if (err) {
	675	pr_err("PPTP: can't add gre protocol\n");
	676	goto out_mem_free;
	677	}
	678
	679	err = proto_register(&pptp_sk_proto, 0);
	680	if (err) {
	681	pr_err("PPTP: can't register sk_proto\n");
	682	goto out_gre_del_protocol;
	683	}
	684
	685	err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
	686	if (err) {
	687	pr_err("PPTP: can't register pppox_proto\n");
	688	goto out_unregister_sk_proto;
	689	}
	690
	691	return 0;
	692
	693	out_unregister_sk_proto:
	694	proto_unregister(&pptp_sk_proto);
	695	out_gre_del_protocol:
	696	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	697	out_mem_free:
	698	vfree(callid_sock);
	699
	700	return err;
	701	}
	702
	703	static void __exit pptp_exit_module(void)
	704	{
	705	unregister_pppox_proto(PX_PROTO_PPTP);
	706	proto_unregister(&pptp_sk_proto);
	707	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	708	vfree(callid_sock);
	709	}
	710
	711	module_init(pptp_init_module);
	712	module_exit(pptp_exit_module);
	713
	714	MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
	715	MODULE_AUTHOR("D. Kozlov ([email protected])");
	716	MODULE_LICENSE("GPL");