[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);
	struct flowi4 fl4;
	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, &fl4, 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;
	struct flowi4 fl4;
	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, &fl4, 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);
31e4543d	178	struct flowi4 fl4;
00959ade DK	179	int islcp;
	180	int len;
	181	unsigned char *data;
	182	__u32 seq_recv;
	183
	184
	185	struct rtable *rt;
	186	struct net_device *tdev;
	187	struct iphdr *iph;
	188	int max_headroom;
	189
	190	if (sk_pppox(po)->sk_state & PPPOX_DEAD)
	191	goto tx_error;
	192
31e4543d	193	rt = ip_route_output_ports(&init_net, &fl4, NULL,
78fbfd8a DM	194	opt->dst_addr.sin_addr.s_addr,
	195	opt->src_addr.sin_addr.s_addr,
	196	0, 0, IPPROTO_GRE,
	197	RT_TOS(0), 0);
	198	if (IS_ERR(rt))
	199	goto tx_error;
	200
00959ade DK	201	tdev = rt->dst.dev;
	202
	203	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(iph) + sizeof(hdr) + 2;
	204
	205	if (skb_headroom(skb) < max_headroom \|\| skb_cloned(skb) \|\| skb_shared(skb)) {
	206	struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
	207	if (!new_skb) {
	208	ip_rt_put(rt);
	209	goto tx_error;
	210	}
	211	if (skb->sk)
	212	skb_set_owner_w(new_skb, skb->sk);
	213	kfree_skb(skb);
	214	skb = new_skb;
	215	}
	216
	217	data = skb->data;
	218	islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
	219
	220	/* compress protocol field */
	221	if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
	222	skb_pull(skb, 1);
	223
	224	/* Put in the address/control bytes if necessary */
	225	if ((opt->ppp_flags & SC_COMP_AC) == 0 \|\| islcp) {
	226	data = skb_push(skb, 2);
	227	data[0] = PPP_ALLSTATIONS;
	228	data[1] = PPP_UI;
	229	}
	230
	231	len = skb->len;
	232
	233	seq_recv = opt->seq_recv;
	234
	235	if (opt->ack_sent == seq_recv)
	236	header_len -= sizeof(hdr->ack);
	237
	238	/* Push down and install GRE header */
	239	skb_push(skb, header_len);
	240	hdr = (struct pptp_gre_header *)(skb->data);
	241
	242	hdr->flags = PPTP_GRE_FLAG_K;
	243	hdr->ver = PPTP_GRE_VER;
	244	hdr->protocol = htons(PPTP_GRE_PROTO);
	245	hdr->call_id = htons(opt->dst_addr.call_id);
	246
	247	hdr->flags \|= PPTP_GRE_FLAG_S;
	248	hdr->seq = htonl(++opt->seq_sent);
	249	if (opt->ack_sent != seq_recv) {
	250	/* send ack with this message */
	251	hdr->ver \|= PPTP_GRE_FLAG_A;
	252	hdr->ack = htonl(seq_recv);
	253	opt->ack_sent = seq_recv;
	254	}
	255	hdr->payload_len = htons(len);
	256
	257	/* Push down and install the IP header. */
	258
	259	skb_reset_transport_header(skb);
	260	skb_push(skb, sizeof(*iph));
	261	skb_reset_network_header(skb);
	262	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
	263	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE \| IPSKB_XFRM_TRANSFORMED \| IPSKB_REROUTED);
	264
265	iph = ip_hdr(skb);
266	iph->version = 4;
267	iph->ihl = sizeof(struct iphdr) >> 2;
268	if (ip_dont_fragment(sk, &rt->dst))
269	iph->frag_off = htons(IP_DF);
270	else
271	iph->frag_off = 0;
272	iph->protocol = IPPROTO_GRE;
273	iph->tos = 0;
274	iph->daddr = rt->rt_dst;
275	iph->saddr = rt->rt_src;
323e126f	276	iph->ttl = ip4_dst_hoplimit(&rt->dst);
00959ade DK	277	iph->tot_len = htons(skb->len);
	278
	279	skb_dst_drop(skb);
	280	skb_dst_set(skb, &rt->dst);
	281
	282	nf_reset(skb);
	283
	284	skb->ip_summed = CHECKSUM_NONE;
	285	ip_select_ident(iph, &rt->dst, NULL);
	286	ip_send_check(iph);
	287
	288	ip_local_out(skb);
	289
	290	tx_error:
	291	return 1;
	292	}
	293
	294	static int pptp_rcv_core(struct sock sk, struct sk_buff skb)
	295	{
	296	struct pppox_sock *po = pppox_sk(sk);
	297	struct pptp_opt *opt = &po->proto.pptp;
	298	int headersize, payload_len, seq;
	299	__u8 *payload;
	300	struct pptp_gre_header *header;
	301
	302	if (!(sk->sk_state & PPPOX_CONNECTED)) {
	303	if (sock_queue_rcv_skb(sk, skb))
	304	goto drop;
	305	return NET_RX_SUCCESS;
	306	}
	307
	308	header = (struct pptp_gre_header *)(skb->data);
	309
	310	/* test if acknowledgement present */
	311	if (PPTP_GRE_IS_A(header->ver)) {
	312	__u32 ack = (PPTP_GRE_IS_S(header->flags)) ?
	313	header->ack : header->seq; /* ack in different place if S = 0 */
	314
	315	ack = ntohl(ack);
	316
	317	if (ack > opt->ack_recv)
	318	opt->ack_recv = ack;
	319	/* also handle sequence number wrap-around */
	320	if (WRAPPED(ack, opt->ack_recv))
	321	opt->ack_recv = ack;
	322	}
	323
	324	/* test if payload present */
	325	if (!PPTP_GRE_IS_S(header->flags))
	326	goto drop;
	327
	328	headersize = sizeof(*header);
	329	payload_len = ntohs(header->payload_len);
	330	seq = ntohl(header->seq);
	331
	332	/* no ack present? */
	333	if (!PPTP_GRE_IS_A(header->ver))
	334	headersize -= sizeof(header->ack);
	335	/* check for incomplete packet (length smaller than expected) */
	336	if (skb->len - headersize < payload_len)
	337	goto drop;
	338
	339	payload = skb->data + headersize;
	340	/* check for expected sequence number */
341	if (seq < opt->seq_recv + 1 \|\| WRAPPED(opt->seq_recv, seq)) {
342	if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
343	(PPP_PROTOCOL(payload) == PPP_LCP) &&
344	((payload[4] == PPP_LCP_ECHOREQ) \|\| (payload[4] == PPP_LCP_ECHOREP)))
345	goto allow_packet;
346	} else {
347	opt->seq_recv = seq;
348	allow_packet:
349	skb_pull(skb, headersize);
350
351	if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
352	/* chop off address/control */
353	if (skb->len < 3)
354	goto drop;
355	skb_pull(skb, 2);
356	}
357
358	if ((*skb->data) & 1) {
359	/* protocol is compressed */
360	skb_push(skb, 1)[0] = 0;
361	}
362
363	skb->ip_summed = CHECKSUM_NONE;
364	skb_set_network_header(skb, skb->head-skb->data);
365	ppp_input(&po->chan, skb);
366
367	return NET_RX_SUCCESS;
368	}
369	drop:
370	kfree_skb(skb);
371	return NET_RX_DROP;
372	}
373
374	static int pptp_rcv(struct sk_buff *skb)
375	{
376	struct pppox_sock *po;
377	struct pptp_gre_header *header;
378	struct iphdr *iph;
379
380	if (skb->pkt_type != PACKET_HOST)
381	goto drop;
382
383	if (!pskb_may_pull(skb, 12))
384	goto drop;
385
386	iph = ip_hdr(skb);
387
388	header = (struct pptp_gre_header *)skb->data;
389
390	if (ntohs(header->protocol) != PPTP_GRE_PROTO \|\| /* PPTP-GRE protocol for PPTP */
391	PPTP_GRE_IS_C(header->flags) \|\| /* flag C should be clear */
392	PPTP_GRE_IS_R(header->flags) \|\| /* flag R should be clear */
393	!PPTP_GRE_IS_K(header->flags) \|\| /* flag K should be set */
394	(header->flags&0xF) != 0) /* routing and recursion ctrl = 0 */
395	/* if invalid, discard this packet */
396	goto drop;
397
398	po = lookup_chan(htons(header->call_id), iph->saddr);
399	if (po) {
400	skb_dst_drop(skb);
401	nf_reset(skb);
402	return sk_receive_skb(sk_pppox(po), skb, 0);
403	}
404	drop:
405	kfree_skb(skb);
406	return NET_RX_DROP;
407	}
408
409	static int pptp_bind(struct socket sock, struct sockaddr uservaddr,
410	int sockaddr_len)
411	{
412	struct sock *sk = sock->sk;
413	struct sockaddr_pppox sp = (struct sockaddr_pppox ) uservaddr;
414	struct pppox_sock *po = pppox_sk(sk);
415	struct pptp_opt *opt = &po->proto.pptp;
416	int error = 0;
417
418	lock_sock(sk);
419
420	opt->src_addr = sp->sa_addr.pptp;
421	if (add_chan(po)) {
422	release_sock(sk);
423	error = -EBUSY;
424	}
425
426	release_sock(sk);
427	return error;
428	}
429
430	static int pptp_connect(struct socket sock, struct sockaddr uservaddr,
431	int sockaddr_len, int flags)
432	{
433	struct sock *sk = sock->sk;
434	struct sockaddr_pppox sp = (struct sockaddr_pppox ) uservaddr;
435	struct pppox_sock *po = pppox_sk(sk);
436	struct pptp_opt *opt = &po->proto.pptp;
437	struct rtable *rt;
31e4543d	438	struct flowi4 fl4;
00959ade DK	439	int error = 0;
	440
	441	if (sp->sa_protocol != PX_PROTO_PPTP)
	442	return -EINVAL;
	443
	444	if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
	445	return -EALREADY;
	446
	447	lock_sock(sk);
	448	/* Check for already bound sockets */
	449	if (sk->sk_state & PPPOX_CONNECTED) {
	450	error = -EBUSY;
	451	goto end;
	452	}
	453
	454	/* Check for already disconnected sockets, on attempts to disconnect */
	455	if (sk->sk_state & PPPOX_DEAD) {
	456	error = -EALREADY;
	457	goto end;
	458	}
	459
	460	if (!opt->src_addr.sin_addr.s_addr \|\| !sp->sa_addr.pptp.sin_addr.s_addr) {
	461	error = -EINVAL;
	462	goto end;
	463	}
	464
	465	po->chan.private = sk;
	466	po->chan.ops = &pptp_chan_ops;
	467
31e4543d	468	rt = ip_route_output_ports(&init_net, &fl4, sk,
78fbfd8a DM	469	opt->dst_addr.sin_addr.s_addr,
	470	opt->src_addr.sin_addr.s_addr,
	471	0, 0,
	472	IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
	473	if (IS_ERR(rt)) {
	474	error = -EHOSTUNREACH;
	475	goto end;
00959ade	476	}
78fbfd8a DM	477	sk_setup_caps(sk, &rt->dst);
78fbfd8a DM	478
00959ade DK	479	po->chan.mtu = dst_mtu(&rt->dst);
	480	if (!po->chan.mtu)
	481	po->chan.mtu = PPP_MTU;
	482	ip_rt_put(rt);
	483	po->chan.mtu -= PPTP_HEADER_OVERHEAD;
	484
	485	po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
	486	error = ppp_register_channel(&po->chan);
	487	if (error) {
	488	pr_err("PPTP: failed to register PPP channel (%d)\n", error);
	489	goto end;
	490	}
	491
	492	opt->dst_addr = sp->sa_addr.pptp;
	493	sk->sk_state = PPPOX_CONNECTED;
	494
	495	end:
	496	release_sock(sk);
	497	return error;
	498	}
	499
	500	static int pptp_getname(struct socket sock, struct sockaddr uaddr,
	501	int *usockaddr_len, int peer)
	502	{
	503	int len = sizeof(struct sockaddr_pppox);
	504	struct sockaddr_pppox sp;
	505
	506	sp.sa_family = AF_PPPOX;
	507	sp.sa_protocol = PX_PROTO_PPTP;
	508	sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
	509
	510	memcpy(uaddr, &sp, len);
	511
	512	*usockaddr_len = len;
	513
	514	return 0;
	515	}
	516
	517	static int pptp_release(struct socket *sock)
	518	{
	519	struct sock *sk = sock->sk;
	520	struct pppox_sock *po;
	521	struct pptp_opt *opt;
	522	int error = 0;
	523
	524	if (!sk)
	525	return 0;
	526
	527	lock_sock(sk);
	528
	529	if (sock_flag(sk, SOCK_DEAD)) {
	530	release_sock(sk);
	531	return -EBADF;
	532	}
	533
	534	po = pppox_sk(sk);
	535	opt = &po->proto.pptp;
	536	del_chan(po);
	537
	538	pppox_unbind_sock(sk);
	539	sk->sk_state = PPPOX_DEAD;
	540
	541	sock_orphan(sk);
	542	sock->sk = NULL;
543
544	release_sock(sk);
545	sock_put(sk);
546
547	return error;
548	}
549
550	static void pptp_sock_destruct(struct sock *sk)
551	{
552	if (!(sk->sk_state & PPPOX_DEAD)) {
553	del_chan(pppox_sk(sk));
554	pppox_unbind_sock(sk);
555	}
556	skb_queue_purge(&sk->sk_receive_queue);
557	}
558
559	static int pptp_create(struct net net, struct socket sock)
560	{
561	int error = -ENOMEM;
562	struct sock *sk;
563	struct pppox_sock *po;
564	struct pptp_opt *opt;
565
566	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto);
567	if (!sk)
568	goto out;
569
570	sock_init_data(sock, sk);
571
572	sock->state = SS_UNCONNECTED;
573	sock->ops = &pptp_ops;
574
575	sk->sk_backlog_rcv = pptp_rcv_core;
576	sk->sk_state = PPPOX_NONE;
577	sk->sk_type = SOCK_STREAM;
578	sk->sk_family = PF_PPPOX;
579	sk->sk_protocol = PX_PROTO_PPTP;
580	sk->sk_destruct = pptp_sock_destruct;
581
582	po = pppox_sk(sk);
583	opt = &po->proto.pptp;
584
585	opt->seq_sent = 0; opt->seq_recv = 0;
586	opt->ack_recv = 0; opt->ack_sent = 0;
587
588	error = 0;
589	out:
590	return error;
591	}
592
593	static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
594	unsigned long arg)
595	{
596	struct sock sk = (struct sock ) chan->private;
597	struct pppox_sock *po = pppox_sk(sk);
598	struct pptp_opt *opt = &po->proto.pptp;
599	void __user argp = (void __user )arg;
600	int __user *p = argp;
601	int err, val;
602
603	err = -EFAULT;
604	switch (cmd) {
605	case PPPIOCGFLAGS:
606	val = opt->ppp_flags;
607	if (put_user(val, p))
608	break;
609	err = 0;
610	break;
611	case PPPIOCSFLAGS:
612	if (get_user(val, p))
613	break;
614	opt->ppp_flags = val & ~SC_RCV_BITS;
615	err = 0;
616	break;
617	default:
618	err = -ENOTTY;
619	}
620
621	return err;
622	}
623
756e64a0	624	static const struct ppp_channel_ops pptp_chan_ops = {
00959ade DK	625	.start_xmit = pptp_xmit,
	626	.ioctl = pptp_ppp_ioctl,
	627	};
	628
	629	static struct proto pptp_sk_proto __read_mostly = {
	630	.name = "PPTP",
	631	.owner = THIS_MODULE,
	632	.obj_size = sizeof(struct pppox_sock),
	633	};
	634
	635	static const struct proto_ops pptp_ops = {
	636	.family = AF_PPPOX,
	637	.owner = THIS_MODULE,
	638	.release = pptp_release,
	639	.bind = pptp_bind,
	640	.connect = pptp_connect,
	641	.socketpair = sock_no_socketpair,
	642	.accept = sock_no_accept,
	643	.getname = pptp_getname,
	644	.poll = sock_no_poll,
	645	.listen = sock_no_listen,
	646	.shutdown = sock_no_shutdown,
	647	.setsockopt = sock_no_setsockopt,
	648	.getsockopt = sock_no_getsockopt,
	649	.sendmsg = sock_no_sendmsg,
	650	.recvmsg = sock_no_recvmsg,
	651	.mmap = sock_no_mmap,
	652	.ioctl = pppox_ioctl,
	653	};
	654
756e64a0	655	static const struct pppox_proto pppox_pptp_proto = {
00959ade DK	656	.create = pptp_create,
	657	.owner = THIS_MODULE,
	658	};
	659
756e64a0	660	static const struct gre_protocol gre_pptp_protocol = {
00959ade DK	661	.handler = pptp_rcv,
	662	};
	663
	664	static int __init pptp_init_module(void)
	665	{
	666	int err = 0;
	667	pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
	668
89bf67f1	669	callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
00959ade DK	670	if (!callid_sock) {
	671	pr_err("PPTP: cann't allocate memory\n");
	672	return -ENOMEM;
	673	}
	674
	675	err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	676	if (err) {
	677	pr_err("PPTP: can't add gre protocol\n");
	678	goto out_mem_free;
	679	}
	680
	681	err = proto_register(&pptp_sk_proto, 0);
	682	if (err) {
	683	pr_err("PPTP: can't register sk_proto\n");
	684	goto out_gre_del_protocol;
	685	}
	686
	687	err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
	688	if (err) {
	689	pr_err("PPTP: can't register pppox_proto\n");
	690	goto out_unregister_sk_proto;
	691	}
	692
	693	return 0;
	694
	695	out_unregister_sk_proto:
	696	proto_unregister(&pptp_sk_proto);
	697	out_gre_del_protocol:
	698	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	699	out_mem_free:
	700	vfree(callid_sock);
	701
	702	return err;
	703	}
	704
	705	static void __exit pptp_exit_module(void)
	706	{
	707	unregister_pppox_proto(PX_PROTO_PPTP);
	708	proto_unregister(&pptp_sk_proto);
	709	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
	710	vfree(callid_sock);
	711	}
	712
	713	module_init(pptp_init_module);
	714	module_exit(pptp_exit_module);
	715
	716	MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
	717	MODULE_AUTHOR("D. Kozlov ([email protected])");
	718	MODULE_LICENSE("GPL");