Loading...
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/ppp-ioctl.h>
27#include <linux/notifier.h>
28#include <linux/file.h>
29#include <linux/in.h>
30#include <linux/ip.h>
31#include <linux/rcupdate.h>
32#include <linux/spinlock.h>
33
34#include <net/sock.h>
35#include <net/protocol.h>
36#include <net/ip.h>
37#include <net/icmp.h>
38#include <net/route.h>
39#include <net/gre.h>
40#include <net/pptp.h>
41
42#include <linux/uaccess.h>
43
44#define PPTP_DRIVER_VERSION "0.8.5"
45
46#define MAX_CALLID 65535
47
48static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
49static struct pppox_sock __rcu **callid_sock;
50
51static DEFINE_SPINLOCK(chan_lock);
52
53static struct proto pptp_sk_proto __read_mostly;
54static const struct ppp_channel_ops pptp_chan_ops;
55static const struct proto_ops pptp_ops;
56
57static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
58{
59 struct pppox_sock *sock;
60 struct pptp_opt *opt;
61
62 rcu_read_lock();
63 sock = rcu_dereference(callid_sock[call_id]);
64 if (sock) {
65 opt = &sock->proto.pptp;
66 if (opt->dst_addr.sin_addr.s_addr != s_addr)
67 sock = NULL;
68 else
69 sock_hold(sk_pppox(sock));
70 }
71 rcu_read_unlock();
72
73 return sock;
74}
75
76static int lookup_chan_dst(u16 call_id, __be32 d_addr)
77{
78 struct pppox_sock *sock;
79 struct pptp_opt *opt;
80 int i;
81
82 rcu_read_lock();
83 i = 1;
84 for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
85 sock = rcu_dereference(callid_sock[i]);
86 if (!sock)
87 continue;
88 opt = &sock->proto.pptp;
89 if (opt->dst_addr.call_id == call_id &&
90 opt->dst_addr.sin_addr.s_addr == d_addr)
91 break;
92 }
93 rcu_read_unlock();
94
95 return i < MAX_CALLID;
96}
97
98static int add_chan(struct pppox_sock *sock,
99 struct pptp_addr *sa)
100{
101 static int call_id;
102
103 spin_lock(&chan_lock);
104 if (!sa->call_id) {
105 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
106 if (call_id == MAX_CALLID) {
107 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
108 if (call_id == MAX_CALLID)
109 goto out_err;
110 }
111 sa->call_id = call_id;
112 } else if (test_bit(sa->call_id, callid_bitmap)) {
113 goto out_err;
114 }
115
116 sock->proto.pptp.src_addr = *sa;
117 set_bit(sa->call_id, callid_bitmap);
118 rcu_assign_pointer(callid_sock[sa->call_id], sock);
119 spin_unlock(&chan_lock);
120
121 return 0;
122
123out_err:
124 spin_unlock(&chan_lock);
125 return -1;
126}
127
128static void del_chan(struct pppox_sock *sock)
129{
130 spin_lock(&chan_lock);
131 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
132 RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
133 spin_unlock(&chan_lock);
134}
135
136static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
137{
138 struct sock *sk = (struct sock *) chan->private;
139 struct pppox_sock *po = pppox_sk(sk);
140 struct net *net = sock_net(sk);
141 struct pptp_opt *opt = &po->proto.pptp;
142 struct pptp_gre_header *hdr;
143 unsigned int header_len = sizeof(*hdr);
144 struct flowi4 fl4;
145 int islcp;
146 int len;
147 unsigned char *data;
148 __u32 seq_recv;
149
150
151 struct rtable *rt;
152 struct net_device *tdev;
153 struct iphdr *iph;
154 int max_headroom;
155
156 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
157 goto tx_error;
158
159 rt = ip_route_output_ports(net, &fl4, NULL,
160 opt->dst_addr.sin_addr.s_addr,
161 opt->src_addr.sin_addr.s_addr,
162 0, 0, IPPROTO_GRE,
163 RT_TOS(0), 0);
164 if (IS_ERR(rt))
165 goto tx_error;
166
167 tdev = rt->dst.dev;
168
169 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
170
171 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
172 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
173 if (!new_skb) {
174 ip_rt_put(rt);
175 goto tx_error;
176 }
177 if (skb->sk)
178 skb_set_owner_w(new_skb, skb->sk);
179 consume_skb(skb);
180 skb = new_skb;
181 }
182
183 data = skb->data;
184 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
185
186 /* compress protocol field */
187 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
188 skb_pull(skb, 1);
189
190 /* Put in the address/control bytes if necessary */
191 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
192 data = skb_push(skb, 2);
193 data[0] = PPP_ALLSTATIONS;
194 data[1] = PPP_UI;
195 }
196
197 len = skb->len;
198
199 seq_recv = opt->seq_recv;
200
201 if (opt->ack_sent == seq_recv)
202 header_len -= sizeof(hdr->ack);
203
204 /* Push down and install GRE header */
205 skb_push(skb, header_len);
206 hdr = (struct pptp_gre_header *)(skb->data);
207
208 hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
209 hdr->gre_hd.protocol = GRE_PROTO_PPP;
210 hdr->call_id = htons(opt->dst_addr.call_id);
211
212 hdr->seq = htonl(++opt->seq_sent);
213 if (opt->ack_sent != seq_recv) {
214 /* send ack with this message */
215 hdr->gre_hd.flags |= GRE_ACK;
216 hdr->ack = htonl(seq_recv);
217 opt->ack_sent = seq_recv;
218 }
219 hdr->payload_len = htons(len);
220
221 /* Push down and install the IP header. */
222
223 skb_reset_transport_header(skb);
224 skb_push(skb, sizeof(*iph));
225 skb_reset_network_header(skb);
226 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
227 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
228
229 iph = ip_hdr(skb);
230 iph->version = 4;
231 iph->ihl = sizeof(struct iphdr) >> 2;
232 if (ip_dont_fragment(sk, &rt->dst))
233 iph->frag_off = htons(IP_DF);
234 else
235 iph->frag_off = 0;
236 iph->protocol = IPPROTO_GRE;
237 iph->tos = 0;
238 iph->daddr = fl4.daddr;
239 iph->saddr = fl4.saddr;
240 iph->ttl = ip4_dst_hoplimit(&rt->dst);
241 iph->tot_len = htons(skb->len);
242
243 skb_dst_drop(skb);
244 skb_dst_set(skb, &rt->dst);
245
246 nf_reset(skb);
247
248 skb->ip_summed = CHECKSUM_NONE;
249 ip_select_ident(net, skb, NULL);
250 ip_send_check(iph);
251
252 ip_local_out(net, skb->sk, skb);
253 return 1;
254
255tx_error:
256 kfree_skb(skb);
257 return 1;
258}
259
260static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
261{
262 struct pppox_sock *po = pppox_sk(sk);
263 struct pptp_opt *opt = &po->proto.pptp;
264 int headersize, payload_len, seq;
265 __u8 *payload;
266 struct pptp_gre_header *header;
267
268 if (!(sk->sk_state & PPPOX_CONNECTED)) {
269 if (sock_queue_rcv_skb(sk, skb))
270 goto drop;
271 return NET_RX_SUCCESS;
272 }
273
274 header = (struct pptp_gre_header *)(skb->data);
275 headersize = sizeof(*header);
276
277 /* test if acknowledgement present */
278 if (GRE_IS_ACK(header->gre_hd.flags)) {
279 __u32 ack;
280
281 if (!pskb_may_pull(skb, headersize))
282 goto drop;
283 header = (struct pptp_gre_header *)(skb->data);
284
285 /* ack in different place if S = 0 */
286 ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
287
288 ack = ntohl(ack);
289
290 if (ack > opt->ack_recv)
291 opt->ack_recv = ack;
292 /* also handle sequence number wrap-around */
293 if (WRAPPED(ack, opt->ack_recv))
294 opt->ack_recv = ack;
295 } else {
296 headersize -= sizeof(header->ack);
297 }
298 /* test if payload present */
299 if (!GRE_IS_SEQ(header->gre_hd.flags))
300 goto drop;
301
302 payload_len = ntohs(header->payload_len);
303 seq = ntohl(header->seq);
304
305 /* check for incomplete packet (length smaller than expected) */
306 if (!pskb_may_pull(skb, headersize + payload_len))
307 goto drop;
308
309 payload = skb->data + headersize;
310 /* check for expected sequence number */
311 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
312 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
313 (PPP_PROTOCOL(payload) == PPP_LCP) &&
314 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
315 goto allow_packet;
316 } else {
317 opt->seq_recv = seq;
318allow_packet:
319 skb_pull(skb, headersize);
320
321 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
322 /* chop off address/control */
323 if (skb->len < 3)
324 goto drop;
325 skb_pull(skb, 2);
326 }
327
328 if ((*skb->data) & 1) {
329 /* protocol is compressed */
330 *(u8 *)skb_push(skb, 1) = 0;
331 }
332
333 skb->ip_summed = CHECKSUM_NONE;
334 skb_set_network_header(skb, skb->head-skb->data);
335 ppp_input(&po->chan, skb);
336
337 return NET_RX_SUCCESS;
338 }
339drop:
340 kfree_skb(skb);
341 return NET_RX_DROP;
342}
343
344static int pptp_rcv(struct sk_buff *skb)
345{
346 struct pppox_sock *po;
347 struct pptp_gre_header *header;
348 struct iphdr *iph;
349
350 if (skb->pkt_type != PACKET_HOST)
351 goto drop;
352
353 if (!pskb_may_pull(skb, 12))
354 goto drop;
355
356 iph = ip_hdr(skb);
357
358 header = (struct pptp_gre_header *)skb->data;
359
360 if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
361 GRE_IS_CSUM(header->gre_hd.flags) || /* flag CSUM should be clear */
362 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
363 !GRE_IS_KEY(header->gre_hd.flags) || /* flag KEY should be set */
364 (header->gre_hd.flags & GRE_FLAGS)) /* flag Recursion Ctrl should be clear */
365 /* if invalid, discard this packet */
366 goto drop;
367
368 po = lookup_chan(htons(header->call_id), iph->saddr);
369 if (po) {
370 skb_dst_drop(skb);
371 nf_reset(skb);
372 return sk_receive_skb(sk_pppox(po), skb, 0);
373 }
374drop:
375 kfree_skb(skb);
376 return NET_RX_DROP;
377}
378
379static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
380 int sockaddr_len)
381{
382 struct sock *sk = sock->sk;
383 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
384 struct pppox_sock *po = pppox_sk(sk);
385 int error = 0;
386
387 if (sockaddr_len < sizeof(struct sockaddr_pppox))
388 return -EINVAL;
389
390 lock_sock(sk);
391
392 if (sk->sk_state & PPPOX_DEAD) {
393 error = -EALREADY;
394 goto out;
395 }
396
397 if (sk->sk_state & PPPOX_BOUND) {
398 error = -EBUSY;
399 goto out;
400 }
401
402 if (add_chan(po, &sp->sa_addr.pptp))
403 error = -EBUSY;
404 else
405 sk->sk_state |= PPPOX_BOUND;
406
407out:
408 release_sock(sk);
409 return error;
410}
411
412static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
413 int sockaddr_len, int flags)
414{
415 struct sock *sk = sock->sk;
416 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
417 struct pppox_sock *po = pppox_sk(sk);
418 struct pptp_opt *opt = &po->proto.pptp;
419 struct rtable *rt;
420 struct flowi4 fl4;
421 int error = 0;
422
423 if (sockaddr_len < sizeof(struct sockaddr_pppox))
424 return -EINVAL;
425
426 if (sp->sa_protocol != PX_PROTO_PPTP)
427 return -EINVAL;
428
429 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
430 return -EALREADY;
431
432 lock_sock(sk);
433 /* Check for already bound sockets */
434 if (sk->sk_state & PPPOX_CONNECTED) {
435 error = -EBUSY;
436 goto end;
437 }
438
439 /* Check for already disconnected sockets, on attempts to disconnect */
440 if (sk->sk_state & PPPOX_DEAD) {
441 error = -EALREADY;
442 goto end;
443 }
444
445 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
446 error = -EINVAL;
447 goto end;
448 }
449
450 po->chan.private = sk;
451 po->chan.ops = &pptp_chan_ops;
452
453 rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
454 opt->dst_addr.sin_addr.s_addr,
455 opt->src_addr.sin_addr.s_addr,
456 0, 0,
457 IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
458 if (IS_ERR(rt)) {
459 error = -EHOSTUNREACH;
460 goto end;
461 }
462 sk_setup_caps(sk, &rt->dst);
463
464 po->chan.mtu = dst_mtu(&rt->dst);
465 if (!po->chan.mtu)
466 po->chan.mtu = PPP_MRU;
467 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
468
469 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
470 error = ppp_register_channel(&po->chan);
471 if (error) {
472 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
473 goto end;
474 }
475
476 opt->dst_addr = sp->sa_addr.pptp;
477 sk->sk_state |= PPPOX_CONNECTED;
478
479 end:
480 release_sock(sk);
481 return error;
482}
483
484static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
485 int peer)
486{
487 int len = sizeof(struct sockaddr_pppox);
488 struct sockaddr_pppox sp;
489
490 memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
491
492 sp.sa_family = AF_PPPOX;
493 sp.sa_protocol = PX_PROTO_PPTP;
494 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
495
496 memcpy(uaddr, &sp, len);
497
498 return len;
499}
500
501static int pptp_release(struct socket *sock)
502{
503 struct sock *sk = sock->sk;
504 struct pppox_sock *po;
505 int error = 0;
506
507 if (!sk)
508 return 0;
509
510 lock_sock(sk);
511
512 if (sock_flag(sk, SOCK_DEAD)) {
513 release_sock(sk);
514 return -EBADF;
515 }
516
517 po = pppox_sk(sk);
518 del_chan(po);
519 synchronize_rcu();
520
521 pppox_unbind_sock(sk);
522 sk->sk_state = PPPOX_DEAD;
523
524 sock_orphan(sk);
525 sock->sk = NULL;
526
527 release_sock(sk);
528 sock_put(sk);
529
530 return error;
531}
532
533static void pptp_sock_destruct(struct sock *sk)
534{
535 if (!(sk->sk_state & PPPOX_DEAD)) {
536 del_chan(pppox_sk(sk));
537 pppox_unbind_sock(sk);
538 }
539 skb_queue_purge(&sk->sk_receive_queue);
540}
541
542static int pptp_create(struct net *net, struct socket *sock, int kern)
543{
544 int error = -ENOMEM;
545 struct sock *sk;
546 struct pppox_sock *po;
547 struct pptp_opt *opt;
548
549 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
550 if (!sk)
551 goto out;
552
553 sock_init_data(sock, sk);
554
555 sock->state = SS_UNCONNECTED;
556 sock->ops = &pptp_ops;
557
558 sk->sk_backlog_rcv = pptp_rcv_core;
559 sk->sk_state = PPPOX_NONE;
560 sk->sk_type = SOCK_STREAM;
561 sk->sk_family = PF_PPPOX;
562 sk->sk_protocol = PX_PROTO_PPTP;
563 sk->sk_destruct = pptp_sock_destruct;
564
565 po = pppox_sk(sk);
566 opt = &po->proto.pptp;
567
568 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
569 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
570
571 error = 0;
572out:
573 return error;
574}
575
576static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
577 unsigned long arg)
578{
579 struct sock *sk = (struct sock *) chan->private;
580 struct pppox_sock *po = pppox_sk(sk);
581 struct pptp_opt *opt = &po->proto.pptp;
582 void __user *argp = (void __user *)arg;
583 int __user *p = argp;
584 int err, val;
585
586 err = -EFAULT;
587 switch (cmd) {
588 case PPPIOCGFLAGS:
589 val = opt->ppp_flags;
590 if (put_user(val, p))
591 break;
592 err = 0;
593 break;
594 case PPPIOCSFLAGS:
595 if (get_user(val, p))
596 break;
597 opt->ppp_flags = val & ~SC_RCV_BITS;
598 err = 0;
599 break;
600 default:
601 err = -ENOTTY;
602 }
603
604 return err;
605}
606
607static const struct ppp_channel_ops pptp_chan_ops = {
608 .start_xmit = pptp_xmit,
609 .ioctl = pptp_ppp_ioctl,
610};
611
612static struct proto pptp_sk_proto __read_mostly = {
613 .name = "PPTP",
614 .owner = THIS_MODULE,
615 .obj_size = sizeof(struct pppox_sock),
616};
617
618static const struct proto_ops pptp_ops = {
619 .family = AF_PPPOX,
620 .owner = THIS_MODULE,
621 .release = pptp_release,
622 .bind = pptp_bind,
623 .connect = pptp_connect,
624 .socketpair = sock_no_socketpair,
625 .accept = sock_no_accept,
626 .getname = pptp_getname,
627 .poll = sock_no_poll,
628 .listen = sock_no_listen,
629 .shutdown = sock_no_shutdown,
630 .setsockopt = sock_no_setsockopt,
631 .getsockopt = sock_no_getsockopt,
632 .sendmsg = sock_no_sendmsg,
633 .recvmsg = sock_no_recvmsg,
634 .mmap = sock_no_mmap,
635 .ioctl = pppox_ioctl,
636};
637
638static const struct pppox_proto pppox_pptp_proto = {
639 .create = pptp_create,
640 .owner = THIS_MODULE,
641};
642
643static const struct gre_protocol gre_pptp_protocol = {
644 .handler = pptp_rcv,
645};
646
647static int __init pptp_init_module(void)
648{
649 int err = 0;
650 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
651
652 callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
653 if (!callid_sock)
654 return -ENOMEM;
655
656 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
657 if (err) {
658 pr_err("PPTP: can't add gre protocol\n");
659 goto out_mem_free;
660 }
661
662 err = proto_register(&pptp_sk_proto, 0);
663 if (err) {
664 pr_err("PPTP: can't register sk_proto\n");
665 goto out_gre_del_protocol;
666 }
667
668 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
669 if (err) {
670 pr_err("PPTP: can't register pppox_proto\n");
671 goto out_unregister_sk_proto;
672 }
673
674 return 0;
675
676out_unregister_sk_proto:
677 proto_unregister(&pptp_sk_proto);
678out_gre_del_protocol:
679 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
680out_mem_free:
681 vfree(callid_sock);
682
683 return err;
684}
685
686static void __exit pptp_exit_module(void)
687{
688 unregister_pppox_proto(PX_PROTO_PPTP);
689 proto_unregister(&pptp_sk_proto);
690 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
691 vfree(callid_sock);
692}
693
694module_init(pptp_init_module);
695module_exit(pptp_exit_module);
696
697MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
698MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
699MODULE_LICENSE("GPL");
700MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);
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
43static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
44static struct pppox_sock __rcu **callid_sock;
45
46static DEFINE_SPINLOCK(chan_lock);
47
48static struct proto pptp_sk_proto __read_mostly;
49static const struct ppp_channel_ops pptp_chan_ops;
50static const struct proto_ops pptp_ops;
51
52static 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
71static 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
93static 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
118out_err:
119 spin_unlock(&chan_lock);
120 return -1;
121}
122
123static 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
131static 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), sk->sk_bound_dev_if);
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_ct(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
250tx_error:
251 kfree_skb(skb);
252 return 1;
253}
254
255static 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) ? ntohl(header->ack) :
282 ntohl(header->seq);
283 if (ack > opt->ack_recv)
284 opt->ack_recv = ack;
285 /* also handle sequence number wrap-around */
286 if (WRAPPED(ack, opt->ack_recv))
287 opt->ack_recv = ack;
288 } else {
289 headersize -= sizeof(header->ack);
290 }
291 /* test if payload present */
292 if (!GRE_IS_SEQ(header->gre_hd.flags))
293 goto drop;
294
295 payload_len = ntohs(header->payload_len);
296 seq = ntohl(header->seq);
297
298 /* check for incomplete packet (length smaller than expected) */
299 if (!pskb_may_pull(skb, headersize + payload_len))
300 goto drop;
301
302 payload = skb->data + headersize;
303 /* check for expected sequence number */
304 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
305 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
306 (PPP_PROTOCOL(payload) == PPP_LCP) &&
307 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
308 goto allow_packet;
309 } else {
310 opt->seq_recv = seq;
311allow_packet:
312 skb_pull(skb, headersize);
313
314 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
315 /* chop off address/control */
316 if (skb->len < 3)
317 goto drop;
318 skb_pull(skb, 2);
319 }
320
321 skb->ip_summed = CHECKSUM_NONE;
322 skb_set_network_header(skb, skb->head-skb->data);
323 ppp_input(&po->chan, skb);
324
325 return NET_RX_SUCCESS;
326 }
327drop:
328 kfree_skb(skb);
329 return NET_RX_DROP;
330}
331
332static int pptp_rcv(struct sk_buff *skb)
333{
334 struct pppox_sock *po;
335 struct pptp_gre_header *header;
336 struct iphdr *iph;
337
338 if (skb->pkt_type != PACKET_HOST)
339 goto drop;
340
341 if (!pskb_may_pull(skb, 12))
342 goto drop;
343
344 iph = ip_hdr(skb);
345
346 header = (struct pptp_gre_header *)skb->data;
347
348 if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
349 GRE_IS_CSUM(header->gre_hd.flags) || /* flag CSUM should be clear */
350 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
351 !GRE_IS_KEY(header->gre_hd.flags) || /* flag KEY should be set */
352 (header->gre_hd.flags & GRE_FLAGS)) /* flag Recursion Ctrl should be clear */
353 /* if invalid, discard this packet */
354 goto drop;
355
356 po = lookup_chan(ntohs(header->call_id), iph->saddr);
357 if (po) {
358 skb_dst_drop(skb);
359 nf_reset_ct(skb);
360 return sk_receive_skb(sk_pppox(po), skb, 0);
361 }
362drop:
363 kfree_skb(skb);
364 return NET_RX_DROP;
365}
366
367static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
368 int sockaddr_len)
369{
370 struct sock *sk = sock->sk;
371 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
372 struct pppox_sock *po = pppox_sk(sk);
373 int error = 0;
374
375 if (sockaddr_len < sizeof(struct sockaddr_pppox))
376 return -EINVAL;
377
378 lock_sock(sk);
379
380 if (sk->sk_state & PPPOX_DEAD) {
381 error = -EALREADY;
382 goto out;
383 }
384
385 if (sk->sk_state & PPPOX_BOUND) {
386 error = -EBUSY;
387 goto out;
388 }
389
390 if (add_chan(po, &sp->sa_addr.pptp))
391 error = -EBUSY;
392 else
393 sk->sk_state |= PPPOX_BOUND;
394
395out:
396 release_sock(sk);
397 return error;
398}
399
400static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
401 int sockaddr_len, int flags)
402{
403 struct sock *sk = sock->sk;
404 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
405 struct pppox_sock *po = pppox_sk(sk);
406 struct pptp_opt *opt = &po->proto.pptp;
407 struct rtable *rt;
408 struct flowi4 fl4;
409 int error = 0;
410
411 if (sockaddr_len < sizeof(struct sockaddr_pppox))
412 return -EINVAL;
413
414 if (sp->sa_protocol != PX_PROTO_PPTP)
415 return -EINVAL;
416
417 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
418 return -EALREADY;
419
420 lock_sock(sk);
421 /* Check for already bound sockets */
422 if (sk->sk_state & PPPOX_CONNECTED) {
423 error = -EBUSY;
424 goto end;
425 }
426
427 /* Check for already disconnected sockets, on attempts to disconnect */
428 if (sk->sk_state & PPPOX_DEAD) {
429 error = -EALREADY;
430 goto end;
431 }
432
433 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
434 error = -EINVAL;
435 goto end;
436 }
437
438 po->chan.private = sk;
439 po->chan.ops = &pptp_chan_ops;
440
441 rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
442 opt->dst_addr.sin_addr.s_addr,
443 opt->src_addr.sin_addr.s_addr,
444 0, 0,
445 IPPROTO_GRE, RT_CONN_FLAGS(sk),
446 sk->sk_bound_dev_if);
447 if (IS_ERR(rt)) {
448 error = -EHOSTUNREACH;
449 goto end;
450 }
451 sk_setup_caps(sk, &rt->dst);
452
453 po->chan.mtu = dst_mtu(&rt->dst);
454 if (!po->chan.mtu)
455 po->chan.mtu = PPP_MRU;
456 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
457
458 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
459 error = ppp_register_channel(&po->chan);
460 if (error) {
461 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
462 goto end;
463 }
464
465 opt->dst_addr = sp->sa_addr.pptp;
466 sk->sk_state |= PPPOX_CONNECTED;
467
468 end:
469 release_sock(sk);
470 return error;
471}
472
473static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
474 int peer)
475{
476 int len = sizeof(struct sockaddr_pppox);
477 struct sockaddr_pppox sp;
478
479 memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
480
481 sp.sa_family = AF_PPPOX;
482 sp.sa_protocol = PX_PROTO_PPTP;
483 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
484
485 memcpy(uaddr, &sp, len);
486
487 return len;
488}
489
490static int pptp_release(struct socket *sock)
491{
492 struct sock *sk = sock->sk;
493 struct pppox_sock *po;
494 int error = 0;
495
496 if (!sk)
497 return 0;
498
499 lock_sock(sk);
500
501 if (sock_flag(sk, SOCK_DEAD)) {
502 release_sock(sk);
503 return -EBADF;
504 }
505
506 po = pppox_sk(sk);
507 del_chan(po);
508 synchronize_rcu();
509
510 pppox_unbind_sock(sk);
511 sk->sk_state = PPPOX_DEAD;
512
513 sock_orphan(sk);
514 sock->sk = NULL;
515
516 release_sock(sk);
517 sock_put(sk);
518
519 return error;
520}
521
522static void pptp_sock_destruct(struct sock *sk)
523{
524 if (!(sk->sk_state & PPPOX_DEAD)) {
525 del_chan(pppox_sk(sk));
526 pppox_unbind_sock(sk);
527 }
528 skb_queue_purge(&sk->sk_receive_queue);
529 dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
530}
531
532static int pptp_create(struct net *net, struct socket *sock, int kern)
533{
534 int error = -ENOMEM;
535 struct sock *sk;
536 struct pppox_sock *po;
537 struct pptp_opt *opt;
538
539 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
540 if (!sk)
541 goto out;
542
543 sock_init_data(sock, sk);
544
545 sock->state = SS_UNCONNECTED;
546 sock->ops = &pptp_ops;
547
548 sk->sk_backlog_rcv = pptp_rcv_core;
549 sk->sk_state = PPPOX_NONE;
550 sk->sk_type = SOCK_STREAM;
551 sk->sk_family = PF_PPPOX;
552 sk->sk_protocol = PX_PROTO_PPTP;
553 sk->sk_destruct = pptp_sock_destruct;
554
555 po = pppox_sk(sk);
556 opt = &po->proto.pptp;
557
558 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
559 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
560
561 error = 0;
562out:
563 return error;
564}
565
566static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
567 unsigned long arg)
568{
569 struct sock *sk = (struct sock *) chan->private;
570 struct pppox_sock *po = pppox_sk(sk);
571 struct pptp_opt *opt = &po->proto.pptp;
572 void __user *argp = (void __user *)arg;
573 int __user *p = argp;
574 int err, val;
575
576 err = -EFAULT;
577 switch (cmd) {
578 case PPPIOCGFLAGS:
579 val = opt->ppp_flags;
580 if (put_user(val, p))
581 break;
582 err = 0;
583 break;
584 case PPPIOCSFLAGS:
585 if (get_user(val, p))
586 break;
587 opt->ppp_flags = val & ~SC_RCV_BITS;
588 err = 0;
589 break;
590 default:
591 err = -ENOTTY;
592 }
593
594 return err;
595}
596
597static const struct ppp_channel_ops pptp_chan_ops = {
598 .start_xmit = pptp_xmit,
599 .ioctl = pptp_ppp_ioctl,
600};
601
602static struct proto pptp_sk_proto __read_mostly = {
603 .name = "PPTP",
604 .owner = THIS_MODULE,
605 .obj_size = sizeof(struct pppox_sock),
606};
607
608static const struct proto_ops pptp_ops = {
609 .family = AF_PPPOX,
610 .owner = THIS_MODULE,
611 .release = pptp_release,
612 .bind = pptp_bind,
613 .connect = pptp_connect,
614 .socketpair = sock_no_socketpair,
615 .accept = sock_no_accept,
616 .getname = pptp_getname,
617 .listen = sock_no_listen,
618 .shutdown = sock_no_shutdown,
619 .sendmsg = sock_no_sendmsg,
620 .recvmsg = sock_no_recvmsg,
621 .mmap = sock_no_mmap,
622 .ioctl = pppox_ioctl,
623#ifdef CONFIG_COMPAT
624 .compat_ioctl = pppox_compat_ioctl,
625#endif
626};
627
628static const struct pppox_proto pppox_pptp_proto = {
629 .create = pptp_create,
630 .owner = THIS_MODULE,
631};
632
633static const struct gre_protocol gre_pptp_protocol = {
634 .handler = pptp_rcv,
635};
636
637static int __init pptp_init_module(void)
638{
639 int err = 0;
640 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
641
642 callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
643 if (!callid_sock)
644 return -ENOMEM;
645
646 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
647 if (err) {
648 pr_err("PPTP: can't add gre protocol\n");
649 goto out_mem_free;
650 }
651
652 err = proto_register(&pptp_sk_proto, 0);
653 if (err) {
654 pr_err("PPTP: can't register sk_proto\n");
655 goto out_gre_del_protocol;
656 }
657
658 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
659 if (err) {
660 pr_err("PPTP: can't register pppox_proto\n");
661 goto out_unregister_sk_proto;
662 }
663
664 return 0;
665
666out_unregister_sk_proto:
667 proto_unregister(&pptp_sk_proto);
668out_gre_del_protocol:
669 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
670out_mem_free:
671 vfree(callid_sock);
672
673 return err;
674}
675
676static void __exit pptp_exit_module(void)
677{
678 unregister_pppox_proto(PX_PROTO_PPTP);
679 proto_unregister(&pptp_sk_proto);
680 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
681 vfree(callid_sock);
682}
683
684module_init(pptp_init_module);
685module_exit(pptp_exit_module);
686
687MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
688MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
689MODULE_LICENSE("GPL");
690MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);