1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Point-to-Point Tunneling Protocol for Linux
4  *
5  *	Authors: Dmitry Kozlov <xeb@mail.ru>
6  */
7 
8 #include <linux/string.h>
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/errno.h>
13 #include <linux/netdevice.h>
14 #include <linux/net.h>
15 #include <linux/skbuff.h>
16 #include <linux/vmalloc.h>
17 #include <linux/init.h>
18 #include <linux/ppp_channel.h>
19 #include <linux/ppp_defs.h>
20 #include <linux/if_pppox.h>
21 #include <linux/ppp-ioctl.h>
22 #include <linux/notifier.h>
23 #include <linux/file.h>
24 #include <linux/in.h>
25 #include <linux/ip.h>
26 #include <linux/rcupdate.h>
27 #include <linux/spinlock.h>
28 
29 #include <net/sock.h>
30 #include <net/protocol.h>
31 #include <net/ip.h>
32 #include <net/icmp.h>
33 #include <net/route.h>
34 #include <net/gre.h>
35 #include <net/pptp.h>
36 
37 #include <linux/uaccess.h>
38 
39 #define PPTP_DRIVER_VERSION "0.8.5"
40 
41 #define MAX_CALLID 65535
42 
43 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
44 static struct pppox_sock __rcu **callid_sock;
45 
46 static DEFINE_SPINLOCK(chan_lock);
47 
48 static struct proto pptp_sk_proto __read_mostly;
49 static const struct ppp_channel_ops pptp_chan_ops;
50 static const struct proto_ops pptp_ops;
51 
lookup_chan(u16 call_id,__be32 s_addr)52 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
53 {
54 	struct pppox_sock *sock;
55 	struct pptp_opt *opt;
56 
57 	rcu_read_lock();
58 	sock = rcu_dereference(callid_sock[call_id]);
59 	if (sock) {
60 		opt = &sock->proto.pptp;
61 		if (opt->dst_addr.sin_addr.s_addr != s_addr)
62 			sock = NULL;
63 		else
64 			sock_hold(sk_pppox(sock));
65 	}
66 	rcu_read_unlock();
67 
68 	return sock;
69 }
70 
lookup_chan_dst(u16 call_id,__be32 d_addr)71 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
72 {
73 	struct pppox_sock *sock;
74 	struct pptp_opt *opt;
75 	int i;
76 
77 	rcu_read_lock();
78 	i = 1;
79 	for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
80 		sock = rcu_dereference(callid_sock[i]);
81 		if (!sock)
82 			continue;
83 		opt = &sock->proto.pptp;
84 		if (opt->dst_addr.call_id == call_id &&
85 			  opt->dst_addr.sin_addr.s_addr == d_addr)
86 			break;
87 	}
88 	rcu_read_unlock();
89 
90 	return i < MAX_CALLID;
91 }
92 
add_chan(struct pppox_sock * sock,struct pptp_addr * sa)93 static int add_chan(struct pppox_sock *sock,
94 		    struct pptp_addr *sa)
95 {
96 	static int call_id;
97 
98 	spin_lock(&chan_lock);
99 	if (!sa->call_id)	{
100 		call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
101 		if (call_id == MAX_CALLID) {
102 			call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
103 			if (call_id == MAX_CALLID)
104 				goto out_err;
105 		}
106 		sa->call_id = call_id;
107 	} else if (test_bit(sa->call_id, callid_bitmap)) {
108 		goto out_err;
109 	}
110 
111 	sock->proto.pptp.src_addr = *sa;
112 	set_bit(sa->call_id, callid_bitmap);
113 	rcu_assign_pointer(callid_sock[sa->call_id], sock);
114 	spin_unlock(&chan_lock);
115 
116 	return 0;
117 
118 out_err:
119 	spin_unlock(&chan_lock);
120 	return -1;
121 }
122 
del_chan(struct pppox_sock * sock)123 static void del_chan(struct pppox_sock *sock)
124 {
125 	spin_lock(&chan_lock);
126 	clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
127 	RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
128 	spin_unlock(&chan_lock);
129 }
130 
pptp_xmit(struct ppp_channel * chan,struct sk_buff * skb)131 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
132 {
133 	struct sock *sk = (struct sock *) chan->private;
134 	struct pppox_sock *po = pppox_sk(sk);
135 	struct net *net = sock_net(sk);
136 	struct pptp_opt *opt = &po->proto.pptp;
137 	struct pptp_gre_header *hdr;
138 	unsigned int header_len = sizeof(*hdr);
139 	struct flowi4 fl4;
140 	int islcp;
141 	int len;
142 	unsigned char *data;
143 	__u32 seq_recv;
144 
145 
146 	struct rtable *rt;
147 	struct net_device *tdev;
148 	struct iphdr  *iph;
149 	int    max_headroom;
150 
151 	if (sk_pppox(po)->sk_state & PPPOX_DEAD)
152 		goto tx_error;
153 
154 	rt = ip_route_output_ports(net, &fl4, NULL,
155 				   opt->dst_addr.sin_addr.s_addr,
156 				   opt->src_addr.sin_addr.s_addr,
157 				   0, 0, IPPROTO_GRE,
158 				   RT_TOS(0), 0);
159 	if (IS_ERR(rt))
160 		goto tx_error;
161 
162 	tdev = rt->dst.dev;
163 
164 	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
165 
166 	if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
167 		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
168 		if (!new_skb) {
169 			ip_rt_put(rt);
170 			goto tx_error;
171 		}
172 		if (skb->sk)
173 			skb_set_owner_w(new_skb, skb->sk);
174 		consume_skb(skb);
175 		skb = new_skb;
176 	}
177 
178 	data = skb->data;
179 	islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
180 
181 	/* compress protocol field */
182 	if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
183 		skb_pull(skb, 1);
184 
185 	/* Put in the address/control bytes if necessary */
186 	if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
187 		data = skb_push(skb, 2);
188 		data[0] = PPP_ALLSTATIONS;
189 		data[1] = PPP_UI;
190 	}
191 
192 	len = skb->len;
193 
194 	seq_recv = opt->seq_recv;
195 
196 	if (opt->ack_sent == seq_recv)
197 		header_len -= sizeof(hdr->ack);
198 
199 	/* Push down and install GRE header */
200 	skb_push(skb, header_len);
201 	hdr = (struct pptp_gre_header *)(skb->data);
202 
203 	hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
204 	hdr->gre_hd.protocol = GRE_PROTO_PPP;
205 	hdr->call_id = htons(opt->dst_addr.call_id);
206 
207 	hdr->seq = htonl(++opt->seq_sent);
208 	if (opt->ack_sent != seq_recv)	{
209 		/* send ack with this message */
210 		hdr->gre_hd.flags |= GRE_ACK;
211 		hdr->ack  = htonl(seq_recv);
212 		opt->ack_sent = seq_recv;
213 	}
214 	hdr->payload_len = htons(len);
215 
216 	/*	Push down and install the IP header. */
217 
218 	skb_reset_transport_header(skb);
219 	skb_push(skb, sizeof(*iph));
220 	skb_reset_network_header(skb);
221 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
222 	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
223 
224 	iph =	ip_hdr(skb);
225 	iph->version =	4;
226 	iph->ihl =	sizeof(struct iphdr) >> 2;
227 	if (ip_dont_fragment(sk, &rt->dst))
228 		iph->frag_off	=	htons(IP_DF);
229 	else
230 		iph->frag_off	=	0;
231 	iph->protocol = IPPROTO_GRE;
232 	iph->tos      = 0;
233 	iph->daddr    = fl4.daddr;
234 	iph->saddr    = fl4.saddr;
235 	iph->ttl      = ip4_dst_hoplimit(&rt->dst);
236 	iph->tot_len  = htons(skb->len);
237 
238 	skb_dst_drop(skb);
239 	skb_dst_set(skb, &rt->dst);
240 
241 	nf_reset(skb);
242 
243 	skb->ip_summed = CHECKSUM_NONE;
244 	ip_select_ident(net, skb, NULL);
245 	ip_send_check(iph);
246 
247 	ip_local_out(net, skb->sk, skb);
248 	return 1;
249 
250 tx_error:
251 	kfree_skb(skb);
252 	return 1;
253 }
254 
pptp_rcv_core(struct sock * sk,struct sk_buff * skb)255 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
256 {
257 	struct pppox_sock *po = pppox_sk(sk);
258 	struct pptp_opt *opt = &po->proto.pptp;
259 	int headersize, payload_len, seq;
260 	__u8 *payload;
261 	struct pptp_gre_header *header;
262 
263 	if (!(sk->sk_state & PPPOX_CONNECTED)) {
264 		if (sock_queue_rcv_skb(sk, skb))
265 			goto drop;
266 		return NET_RX_SUCCESS;
267 	}
268 
269 	header = (struct pptp_gre_header *)(skb->data);
270 	headersize  = sizeof(*header);
271 
272 	/* test if acknowledgement present */
273 	if (GRE_IS_ACK(header->gre_hd.flags)) {
274 		__u32 ack;
275 
276 		if (!pskb_may_pull(skb, headersize))
277 			goto drop;
278 		header = (struct pptp_gre_header *)(skb->data);
279 
280 		/* ack in different place if S = 0 */
281 		ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
282 
283 		ack = ntohl(ack);
284 
285 		if (ack > opt->ack_recv)
286 			opt->ack_recv = ack;
287 		/* also handle sequence number wrap-around  */
288 		if (WRAPPED(ack, opt->ack_recv))
289 			opt->ack_recv = ack;
290 	} else {
291 		headersize -= sizeof(header->ack);
292 	}
293 	/* test if payload present */
294 	if (!GRE_IS_SEQ(header->gre_hd.flags))
295 		goto drop;
296 
297 	payload_len = ntohs(header->payload_len);
298 	seq         = ntohl(header->seq);
299 
300 	/* check for incomplete packet (length smaller than expected) */
301 	if (!pskb_may_pull(skb, headersize + payload_len))
302 		goto drop;
303 
304 	payload = skb->data + headersize;
305 	/* check for expected sequence number */
306 	if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
307 		if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
308 				(PPP_PROTOCOL(payload) == PPP_LCP) &&
309 				((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
310 			goto allow_packet;
311 	} else {
312 		opt->seq_recv = seq;
313 allow_packet:
314 		skb_pull(skb, headersize);
315 
316 		if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
317 			/* chop off address/control */
318 			if (skb->len < 3)
319 				goto drop;
320 			skb_pull(skb, 2);
321 		}
322 
323 		skb->ip_summed = CHECKSUM_NONE;
324 		skb_set_network_header(skb, skb->head-skb->data);
325 		ppp_input(&po->chan, skb);
326 
327 		return NET_RX_SUCCESS;
328 	}
329 drop:
330 	kfree_skb(skb);
331 	return NET_RX_DROP;
332 }
333 
pptp_rcv(struct sk_buff * skb)334 static int pptp_rcv(struct sk_buff *skb)
335 {
336 	struct pppox_sock *po;
337 	struct pptp_gre_header *header;
338 	struct iphdr *iph;
339 
340 	if (skb->pkt_type != PACKET_HOST)
341 		goto drop;
342 
343 	if (!pskb_may_pull(skb, 12))
344 		goto drop;
345 
346 	iph = ip_hdr(skb);
347 
348 	header = (struct pptp_gre_header *)skb->data;
349 
350 	if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
351 		GRE_IS_CSUM(header->gre_hd.flags) ||    /* flag CSUM should be clear */
352 		GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
353 		!GRE_IS_KEY(header->gre_hd.flags) ||    /* flag KEY should be set */
354 		(header->gre_hd.flags & GRE_FLAGS))     /* flag Recursion Ctrl should be clear */
355 		/* if invalid, discard this packet */
356 		goto drop;
357 
358 	po = lookup_chan(htons(header->call_id), iph->saddr);
359 	if (po) {
360 		skb_dst_drop(skb);
361 		nf_reset(skb);
362 		return sk_receive_skb(sk_pppox(po), skb, 0);
363 	}
364 drop:
365 	kfree_skb(skb);
366 	return NET_RX_DROP;
367 }
368 
pptp_bind(struct socket * sock,struct sockaddr * uservaddr,int sockaddr_len)369 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
370 	int sockaddr_len)
371 {
372 	struct sock *sk = sock->sk;
373 	struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
374 	struct pppox_sock *po = pppox_sk(sk);
375 	int error = 0;
376 
377 	if (sockaddr_len < sizeof(struct sockaddr_pppox))
378 		return -EINVAL;
379 
380 	lock_sock(sk);
381 
382 	if (sk->sk_state & PPPOX_DEAD) {
383 		error = -EALREADY;
384 		goto out;
385 	}
386 
387 	if (sk->sk_state & PPPOX_BOUND) {
388 		error = -EBUSY;
389 		goto out;
390 	}
391 
392 	if (add_chan(po, &sp->sa_addr.pptp))
393 		error = -EBUSY;
394 	else
395 		sk->sk_state |= PPPOX_BOUND;
396 
397 out:
398 	release_sock(sk);
399 	return error;
400 }
401 
pptp_connect(struct socket * sock,struct sockaddr * uservaddr,int sockaddr_len,int flags)402 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
403 	int sockaddr_len, int flags)
404 {
405 	struct sock *sk = sock->sk;
406 	struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
407 	struct pppox_sock *po = pppox_sk(sk);
408 	struct pptp_opt *opt = &po->proto.pptp;
409 	struct rtable *rt;
410 	struct flowi4 fl4;
411 	int error = 0;
412 
413 	if (sockaddr_len < sizeof(struct sockaddr_pppox))
414 		return -EINVAL;
415 
416 	if (sp->sa_protocol != PX_PROTO_PPTP)
417 		return -EINVAL;
418 
419 	if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
420 		return -EALREADY;
421 
422 	lock_sock(sk);
423 	/* Check for already bound sockets */
424 	if (sk->sk_state & PPPOX_CONNECTED) {
425 		error = -EBUSY;
426 		goto end;
427 	}
428 
429 	/* Check for already disconnected sockets, on attempts to disconnect */
430 	if (sk->sk_state & PPPOX_DEAD) {
431 		error = -EALREADY;
432 		goto end;
433 	}
434 
435 	if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
436 		error = -EINVAL;
437 		goto end;
438 	}
439 
440 	po->chan.private = sk;
441 	po->chan.ops = &pptp_chan_ops;
442 
443 	rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
444 				   opt->dst_addr.sin_addr.s_addr,
445 				   opt->src_addr.sin_addr.s_addr,
446 				   0, 0,
447 				   IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
448 	if (IS_ERR(rt)) {
449 		error = -EHOSTUNREACH;
450 		goto end;
451 	}
452 	sk_setup_caps(sk, &rt->dst);
453 
454 	po->chan.mtu = dst_mtu(&rt->dst);
455 	if (!po->chan.mtu)
456 		po->chan.mtu = PPP_MRU;
457 	po->chan.mtu -= PPTP_HEADER_OVERHEAD;
458 
459 	po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
460 	error = ppp_register_channel(&po->chan);
461 	if (error) {
462 		pr_err("PPTP: failed to register PPP channel (%d)\n", error);
463 		goto end;
464 	}
465 
466 	opt->dst_addr = sp->sa_addr.pptp;
467 	sk->sk_state |= PPPOX_CONNECTED;
468 
469  end:
470 	release_sock(sk);
471 	return error;
472 }
473 
pptp_getname(struct socket * sock,struct sockaddr * uaddr,int peer)474 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
475 	int peer)
476 {
477 	int len = sizeof(struct sockaddr_pppox);
478 	struct sockaddr_pppox sp;
479 
480 	memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
481 
482 	sp.sa_family    = AF_PPPOX;
483 	sp.sa_protocol  = PX_PROTO_PPTP;
484 	sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
485 
486 	memcpy(uaddr, &sp, len);
487 
488 	return len;
489 }
490 
pptp_release(struct socket * sock)491 static int pptp_release(struct socket *sock)
492 {
493 	struct sock *sk = sock->sk;
494 	struct pppox_sock *po;
495 	int error = 0;
496 
497 	if (!sk)
498 		return 0;
499 
500 	lock_sock(sk);
501 
502 	if (sock_flag(sk, SOCK_DEAD)) {
503 		release_sock(sk);
504 		return -EBADF;
505 	}
506 
507 	po = pppox_sk(sk);
508 	del_chan(po);
509 	synchronize_rcu();
510 
511 	pppox_unbind_sock(sk);
512 	sk->sk_state = PPPOX_DEAD;
513 
514 	sock_orphan(sk);
515 	sock->sk = NULL;
516 
517 	release_sock(sk);
518 	sock_put(sk);
519 
520 	return error;
521 }
522 
pptp_sock_destruct(struct sock * sk)523 static void pptp_sock_destruct(struct sock *sk)
524 {
525 	if (!(sk->sk_state & PPPOX_DEAD)) {
526 		del_chan(pppox_sk(sk));
527 		pppox_unbind_sock(sk);
528 	}
529 	skb_queue_purge(&sk->sk_receive_queue);
530 	dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
531 }
532 
pptp_create(struct net * net,struct socket * sock,int kern)533 static int pptp_create(struct net *net, struct socket *sock, int kern)
534 {
535 	int error = -ENOMEM;
536 	struct sock *sk;
537 	struct pppox_sock *po;
538 	struct pptp_opt *opt;
539 
540 	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
541 	if (!sk)
542 		goto out;
543 
544 	sock_init_data(sock, sk);
545 
546 	sock->state = SS_UNCONNECTED;
547 	sock->ops   = &pptp_ops;
548 
549 	sk->sk_backlog_rcv = pptp_rcv_core;
550 	sk->sk_state       = PPPOX_NONE;
551 	sk->sk_type        = SOCK_STREAM;
552 	sk->sk_family      = PF_PPPOX;
553 	sk->sk_protocol    = PX_PROTO_PPTP;
554 	sk->sk_destruct    = pptp_sock_destruct;
555 
556 	po = pppox_sk(sk);
557 	opt = &po->proto.pptp;
558 
559 	opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
560 	opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
561 
562 	error = 0;
563 out:
564 	return error;
565 }
566 
pptp_ppp_ioctl(struct ppp_channel * chan,unsigned int cmd,unsigned long arg)567 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
568 	unsigned long arg)
569 {
570 	struct sock *sk = (struct sock *) chan->private;
571 	struct pppox_sock *po = pppox_sk(sk);
572 	struct pptp_opt *opt = &po->proto.pptp;
573 	void __user *argp = (void __user *)arg;
574 	int __user *p = argp;
575 	int err, val;
576 
577 	err = -EFAULT;
578 	switch (cmd) {
579 	case PPPIOCGFLAGS:
580 		val = opt->ppp_flags;
581 		if (put_user(val, p))
582 			break;
583 		err = 0;
584 		break;
585 	case PPPIOCSFLAGS:
586 		if (get_user(val, p))
587 			break;
588 		opt->ppp_flags = val & ~SC_RCV_BITS;
589 		err = 0;
590 		break;
591 	default:
592 		err = -ENOTTY;
593 	}
594 
595 	return err;
596 }
597 
598 static const struct ppp_channel_ops pptp_chan_ops = {
599 	.start_xmit = pptp_xmit,
600 	.ioctl      = pptp_ppp_ioctl,
601 };
602 
603 static struct proto pptp_sk_proto __read_mostly = {
604 	.name     = "PPTP",
605 	.owner    = THIS_MODULE,
606 	.obj_size = sizeof(struct pppox_sock),
607 };
608 
609 static const struct proto_ops pptp_ops = {
610 	.family     = AF_PPPOX,
611 	.owner      = THIS_MODULE,
612 	.release    = pptp_release,
613 	.bind       = pptp_bind,
614 	.connect    = pptp_connect,
615 	.socketpair = sock_no_socketpair,
616 	.accept     = sock_no_accept,
617 	.getname    = pptp_getname,
618 	.listen     = sock_no_listen,
619 	.shutdown   = sock_no_shutdown,
620 	.setsockopt = sock_no_setsockopt,
621 	.getsockopt = sock_no_getsockopt,
622 	.sendmsg    = sock_no_sendmsg,
623 	.recvmsg    = sock_no_recvmsg,
624 	.mmap       = sock_no_mmap,
625 	.ioctl      = pppox_ioctl,
626 #ifdef CONFIG_COMPAT
627 	.compat_ioctl = pppox_compat_ioctl,
628 #endif
629 };
630 
631 static const struct pppox_proto pppox_pptp_proto = {
632 	.create = pptp_create,
633 	.owner  = THIS_MODULE,
634 };
635 
636 static const struct gre_protocol gre_pptp_protocol = {
637 	.handler = pptp_rcv,
638 };
639 
pptp_init_module(void)640 static int __init pptp_init_module(void)
641 {
642 	int err = 0;
643 	pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
644 
645 	callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
646 	if (!callid_sock)
647 		return -ENOMEM;
648 
649 	err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
650 	if (err) {
651 		pr_err("PPTP: can't add gre protocol\n");
652 		goto out_mem_free;
653 	}
654 
655 	err = proto_register(&pptp_sk_proto, 0);
656 	if (err) {
657 		pr_err("PPTP: can't register sk_proto\n");
658 		goto out_gre_del_protocol;
659 	}
660 
661 	err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
662 	if (err) {
663 		pr_err("PPTP: can't register pppox_proto\n");
664 		goto out_unregister_sk_proto;
665 	}
666 
667 	return 0;
668 
669 out_unregister_sk_proto:
670 	proto_unregister(&pptp_sk_proto);
671 out_gre_del_protocol:
672 	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
673 out_mem_free:
674 	vfree(callid_sock);
675 
676 	return err;
677 }
678 
pptp_exit_module(void)679 static void __exit pptp_exit_module(void)
680 {
681 	unregister_pppox_proto(PX_PROTO_PPTP);
682 	proto_unregister(&pptp_sk_proto);
683 	gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
684 	vfree(callid_sock);
685 }
686 
687 module_init(pptp_init_module);
688 module_exit(pptp_exit_module);
689 
690 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
691 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
692 MODULE_LICENSE("GPL");
693 MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);
694