Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Point-to-Point Tunneling Protocol for Linux
3 *
4 * Authors: Dmitry Kozlov <xeb@mail.ru>
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
50static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
51static struct pppox_sock **callid_sock;
52
53static DEFINE_SPINLOCK(chan_lock);
54
55static struct proto pptp_sk_proto __read_mostly;
56static const struct ppp_channel_ops pptp_chan_ops;
57static 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))
84struct 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
94static 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
113static 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
135static 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
157out_err:
158 spin_unlock(&chan_lock);
159 return -1;
160}
161
162static 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
171static 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);
178 struct flowi4 fl4;
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
193 rt = ip_route_output_ports(&init_net, &fl4, NULL,
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
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 = fl4.daddr;
275 iph->saddr = fl4.saddr;
276 iph->ttl = ip4_dst_hoplimit(&rt->dst);
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
290tx_error:
291 return 1;
292}
293
294static 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;
348allow_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 }
369drop:
370 kfree_skb(skb);
371 return NET_RX_DROP;
372}
373
374static 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 }
404drop:
405 kfree_skb(skb);
406 return NET_RX_DROP;
407}
408
409static 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
430static 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;
438 struct flowi4 fl4;
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
468 rt = ip_route_output_ports(&init_net, &fl4, sk,
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;
476 }
477 sk_setup_caps(sk, &rt->dst);
478
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
500static 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
517static 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
550static 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
559static 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;
589out:
590 return error;
591}
592
593static 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
624static const struct ppp_channel_ops pptp_chan_ops = {
625 .start_xmit = pptp_xmit,
626 .ioctl = pptp_ppp_ioctl,
627};
628
629static struct proto pptp_sk_proto __read_mostly = {
630 .name = "PPTP",
631 .owner = THIS_MODULE,
632 .obj_size = sizeof(struct pppox_sock),
633};
634
635static 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
655static const struct pppox_proto pppox_pptp_proto = {
656 .create = pptp_create,
657 .owner = THIS_MODULE,
658};
659
660static const struct gre_protocol gre_pptp_protocol = {
661 .handler = pptp_rcv,
662};
663
664static int __init pptp_init_module(void)
665{
666 int err = 0;
667 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
668
669 callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
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
695out_unregister_sk_proto:
696 proto_unregister(&pptp_sk_proto);
697out_gre_del_protocol:
698 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
699out_mem_free:
700 vfree(callid_sock);
701
702 return err;
703}
704
705static 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
713module_init(pptp_init_module);
714module_exit(pptp_exit_module);
715
716MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
717MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
718MODULE_LICENSE("GPL");