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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/security.h>
28#include <linux/spinlock.h>
29
30#include <net/sock.h>
31#include <net/protocol.h>
32#include <net/ip.h>
33#include <net/icmp.h>
34#include <net/route.h>
35#include <net/gre.h>
36#include <net/pptp.h>
37
38#include <linux/uaccess.h>
39
40#define PPTP_DRIVER_VERSION "0.8.5"
41
42#define MAX_CALLID 65535
43
44static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
45static struct pppox_sock __rcu **callid_sock;
46
47static DEFINE_SPINLOCK(chan_lock);
48
49static struct proto pptp_sk_proto __read_mostly;
50static const struct ppp_channel_ops pptp_chan_ops;
51static const struct proto_ops pptp_ops;
52
53static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
54{
55 struct pppox_sock *sock;
56 struct pptp_opt *opt;
57
58 rcu_read_lock();
59 sock = rcu_dereference(callid_sock[call_id]);
60 if (sock) {
61 opt = &sock->proto.pptp;
62 if (opt->dst_addr.sin_addr.s_addr != s_addr)
63 sock = NULL;
64 else
65 sock_hold(sk_pppox(sock));
66 }
67 rcu_read_unlock();
68
69 return sock;
70}
71
72static int lookup_chan_dst(u16 call_id, __be32 d_addr)
73{
74 struct pppox_sock *sock;
75 struct pptp_opt *opt;
76 int i;
77
78 rcu_read_lock();
79 i = 1;
80 for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
81 sock = rcu_dereference(callid_sock[i]);
82 if (!sock)
83 continue;
84 opt = &sock->proto.pptp;
85 if (opt->dst_addr.call_id == call_id &&
86 opt->dst_addr.sin_addr.s_addr == d_addr)
87 break;
88 }
89 rcu_read_unlock();
90
91 return i < MAX_CALLID;
92}
93
94static int add_chan(struct pppox_sock *sock,
95 struct pptp_addr *sa)
96{
97 static int call_id;
98
99 spin_lock(&chan_lock);
100 if (!sa->call_id) {
101 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
102 if (call_id == MAX_CALLID) {
103 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
104 if (call_id == MAX_CALLID)
105 goto out_err;
106 }
107 sa->call_id = call_id;
108 } else if (test_bit(sa->call_id, callid_bitmap)) {
109 goto out_err;
110 }
111
112 sock->proto.pptp.src_addr = *sa;
113 set_bit(sa->call_id, callid_bitmap);
114 rcu_assign_pointer(callid_sock[sa->call_id], sock);
115 spin_unlock(&chan_lock);
116
117 return 0;
118
119out_err:
120 spin_unlock(&chan_lock);
121 return -1;
122}
123
124static void del_chan(struct pppox_sock *sock)
125{
126 spin_lock(&chan_lock);
127 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
128 RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
129 spin_unlock(&chan_lock);
130}
131
132static struct rtable *pptp_route_output(const struct pppox_sock *po,
133 struct flowi4 *fl4)
134{
135 const struct sock *sk = &po->sk;
136 struct net *net;
137
138 net = sock_net(sk);
139 flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark, 0,
140 RT_SCOPE_UNIVERSE, IPPROTO_GRE, 0,
141 po->proto.pptp.dst_addr.sin_addr.s_addr,
142 po->proto.pptp.src_addr.sin_addr.s_addr,
143 0, 0, sock_net_uid(net, sk));
144 security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
145
146 return ip_route_output_flow(net, fl4, sk);
147}
148
149static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
150{
151 struct sock *sk = chan->private;
152 struct pppox_sock *po = pppox_sk(sk);
153 struct net *net = sock_net(sk);
154 struct pptp_opt *opt = &po->proto.pptp;
155 struct pptp_gre_header *hdr;
156 unsigned int header_len = sizeof(*hdr);
157 struct flowi4 fl4;
158 int islcp;
159 int len;
160 unsigned char *data;
161 __u32 seq_recv;
162
163
164 struct rtable *rt;
165 struct net_device *tdev;
166 struct iphdr *iph;
167 int max_headroom;
168
169 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
170 goto tx_error;
171
172 rt = pptp_route_output(po, &fl4);
173 if (IS_ERR(rt))
174 goto tx_error;
175
176 tdev = rt->dst.dev;
177
178 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
179
180 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
181 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
182 if (!new_skb) {
183 ip_rt_put(rt);
184 goto tx_error;
185 }
186 if (skb->sk)
187 skb_set_owner_w(new_skb, skb->sk);
188 consume_skb(skb);
189 skb = new_skb;
190 }
191
192 data = skb->data;
193 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
194
195 /* compress protocol field */
196 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
197 skb_pull(skb, 1);
198
199 /* Put in the address/control bytes if necessary */
200 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
201 data = skb_push(skb, 2);
202 data[0] = PPP_ALLSTATIONS;
203 data[1] = PPP_UI;
204 }
205
206 len = skb->len;
207
208 seq_recv = opt->seq_recv;
209
210 if (opt->ack_sent == seq_recv)
211 header_len -= sizeof(hdr->ack);
212
213 /* Push down and install GRE header */
214 skb_push(skb, header_len);
215 hdr = (struct pptp_gre_header *)(skb->data);
216
217 hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
218 hdr->gre_hd.protocol = GRE_PROTO_PPP;
219 hdr->call_id = htons(opt->dst_addr.call_id);
220
221 hdr->seq = htonl(++opt->seq_sent);
222 if (opt->ack_sent != seq_recv) {
223 /* send ack with this message */
224 hdr->gre_hd.flags |= GRE_ACK;
225 hdr->ack = htonl(seq_recv);
226 opt->ack_sent = seq_recv;
227 }
228 hdr->payload_len = htons(len);
229
230 /* Push down and install the IP header. */
231
232 skb_reset_transport_header(skb);
233 skb_push(skb, sizeof(*iph));
234 skb_reset_network_header(skb);
235 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
236 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
237
238 iph = ip_hdr(skb);
239 iph->version = 4;
240 iph->ihl = sizeof(struct iphdr) >> 2;
241 if (ip_dont_fragment(sk, &rt->dst))
242 iph->frag_off = htons(IP_DF);
243 else
244 iph->frag_off = 0;
245 iph->protocol = IPPROTO_GRE;
246 iph->tos = 0;
247 iph->daddr = fl4.daddr;
248 iph->saddr = fl4.saddr;
249 iph->ttl = ip4_dst_hoplimit(&rt->dst);
250 iph->tot_len = htons(skb->len);
251
252 skb_dst_drop(skb);
253 skb_dst_set(skb, &rt->dst);
254
255 nf_reset_ct(skb);
256
257 skb->ip_summed = CHECKSUM_NONE;
258 ip_select_ident(net, skb, NULL);
259 ip_send_check(iph);
260
261 ip_local_out(net, skb->sk, skb);
262 return 1;
263
264tx_error:
265 kfree_skb(skb);
266 return 1;
267}
268
269static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
270{
271 struct pppox_sock *po = pppox_sk(sk);
272 struct pptp_opt *opt = &po->proto.pptp;
273 int headersize, payload_len, seq;
274 __u8 *payload;
275 struct pptp_gre_header *header;
276
277 if (!(sk->sk_state & PPPOX_CONNECTED)) {
278 if (sock_queue_rcv_skb(sk, skb))
279 goto drop;
280 return NET_RX_SUCCESS;
281 }
282
283 header = (struct pptp_gre_header *)(skb->data);
284 headersize = sizeof(*header);
285
286 /* test if acknowledgement present */
287 if (GRE_IS_ACK(header->gre_hd.flags)) {
288 __u32 ack;
289
290 if (!pskb_may_pull(skb, headersize))
291 goto drop;
292 header = (struct pptp_gre_header *)(skb->data);
293
294 /* ack in different place if S = 0 */
295 ack = GRE_IS_SEQ(header->gre_hd.flags) ? ntohl(header->ack) :
296 ntohl(header->seq);
297 if (ack > opt->ack_recv)
298 opt->ack_recv = ack;
299 /* also handle sequence number wrap-around */
300 if (WRAPPED(ack, opt->ack_recv))
301 opt->ack_recv = ack;
302 } else {
303 headersize -= sizeof(header->ack);
304 }
305 /* test if payload present */
306 if (!GRE_IS_SEQ(header->gre_hd.flags))
307 goto drop;
308
309 payload_len = ntohs(header->payload_len);
310 seq = ntohl(header->seq);
311
312 /* check for incomplete packet (length smaller than expected) */
313 if (!pskb_may_pull(skb, headersize + payload_len))
314 goto drop;
315
316 payload = skb->data + headersize;
317 /* check for expected sequence number */
318 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
319 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
320 (PPP_PROTOCOL(payload) == PPP_LCP) &&
321 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
322 goto allow_packet;
323 } else {
324 opt->seq_recv = seq;
325allow_packet:
326 skb_pull(skb, headersize);
327
328 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
329 /* chop off address/control */
330 if (skb->len < 3)
331 goto drop;
332 skb_pull(skb, 2);
333 }
334
335 skb->ip_summed = CHECKSUM_NONE;
336 skb_set_network_header(skb, skb->head-skb->data);
337 ppp_input(&po->chan, skb);
338
339 return NET_RX_SUCCESS;
340 }
341drop:
342 kfree_skb(skb);
343 return NET_RX_DROP;
344}
345
346static int pptp_rcv(struct sk_buff *skb)
347{
348 struct pppox_sock *po;
349 struct pptp_gre_header *header;
350 struct iphdr *iph;
351
352 if (skb->pkt_type != PACKET_HOST)
353 goto drop;
354
355 if (!pskb_may_pull(skb, 12))
356 goto drop;
357
358 iph = ip_hdr(skb);
359
360 header = (struct pptp_gre_header *)skb->data;
361
362 if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
363 GRE_IS_CSUM(header->gre_hd.flags) || /* flag CSUM should be clear */
364 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
365 !GRE_IS_KEY(header->gre_hd.flags) || /* flag KEY should be set */
366 (header->gre_hd.flags & GRE_FLAGS)) /* flag Recursion Ctrl should be clear */
367 /* if invalid, discard this packet */
368 goto drop;
369
370 po = lookup_chan(ntohs(header->call_id), iph->saddr);
371 if (po) {
372 skb_dst_drop(skb);
373 nf_reset_ct(skb);
374 return sk_receive_skb(sk_pppox(po), skb, 0);
375 }
376drop:
377 kfree_skb(skb);
378 return NET_RX_DROP;
379}
380
381static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
382 int sockaddr_len)
383{
384 struct sock *sk = sock->sk;
385 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
386 struct pppox_sock *po = pppox_sk(sk);
387 int error = 0;
388
389 if (sockaddr_len < sizeof(struct sockaddr_pppox))
390 return -EINVAL;
391
392 lock_sock(sk);
393
394 if (sk->sk_state & PPPOX_DEAD) {
395 error = -EALREADY;
396 goto out;
397 }
398
399 if (sk->sk_state & PPPOX_BOUND) {
400 error = -EBUSY;
401 goto out;
402 }
403
404 if (add_chan(po, &sp->sa_addr.pptp))
405 error = -EBUSY;
406 else
407 sk->sk_state |= PPPOX_BOUND;
408
409out:
410 release_sock(sk);
411 return error;
412}
413
414static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
415 int sockaddr_len, int flags)
416{
417 struct sock *sk = sock->sk;
418 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
419 struct pppox_sock *po = pppox_sk(sk);
420 struct pptp_opt *opt = &po->proto.pptp;
421 struct rtable *rt;
422 struct flowi4 fl4;
423 int error = 0;
424
425 if (sockaddr_len < sizeof(struct sockaddr_pppox))
426 return -EINVAL;
427
428 if (sp->sa_protocol != PX_PROTO_PPTP)
429 return -EINVAL;
430
431 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
432 return -EALREADY;
433
434 lock_sock(sk);
435 /* Check for already bound sockets */
436 if (sk->sk_state & PPPOX_CONNECTED) {
437 error = -EBUSY;
438 goto end;
439 }
440
441 /* Check for already disconnected sockets, on attempts to disconnect */
442 if (sk->sk_state & PPPOX_DEAD) {
443 error = -EALREADY;
444 goto end;
445 }
446
447 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
448 error = -EINVAL;
449 goto end;
450 }
451
452 po->chan.private = sk;
453 po->chan.ops = &pptp_chan_ops;
454
455 rt = pptp_route_output(po, &fl4);
456 if (IS_ERR(rt)) {
457 error = -EHOSTUNREACH;
458 goto end;
459 }
460 sk_setup_caps(sk, &rt->dst);
461
462 po->chan.mtu = dst_mtu(&rt->dst);
463 if (!po->chan.mtu)
464 po->chan.mtu = PPP_MRU;
465 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
466
467 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
468 error = ppp_register_channel(&po->chan);
469 if (error) {
470 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
471 goto end;
472 }
473
474 opt->dst_addr = sp->sa_addr.pptp;
475 sk->sk_state |= PPPOX_CONNECTED;
476
477 end:
478 release_sock(sk);
479 return error;
480}
481
482static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
483 int peer)
484{
485 int len = sizeof(struct sockaddr_pppox);
486 struct sockaddr_pppox sp;
487
488 memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
489
490 sp.sa_family = AF_PPPOX;
491 sp.sa_protocol = PX_PROTO_PPTP;
492 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
493
494 memcpy(uaddr, &sp, len);
495
496 return len;
497}
498
499static int pptp_release(struct socket *sock)
500{
501 struct sock *sk = sock->sk;
502 struct pppox_sock *po;
503 int error = 0;
504
505 if (!sk)
506 return 0;
507
508 lock_sock(sk);
509
510 if (sock_flag(sk, SOCK_DEAD)) {
511 release_sock(sk);
512 return -EBADF;
513 }
514
515 po = pppox_sk(sk);
516 del_chan(po);
517 synchronize_rcu();
518
519 pppox_unbind_sock(sk);
520 sk->sk_state = PPPOX_DEAD;
521
522 sock_orphan(sk);
523 sock->sk = NULL;
524
525 release_sock(sk);
526 sock_put(sk);
527
528 return error;
529}
530
531static void pptp_sock_destruct(struct sock *sk)
532{
533 if (!(sk->sk_state & PPPOX_DEAD)) {
534 del_chan(pppox_sk(sk));
535 pppox_unbind_sock(sk);
536 }
537 skb_queue_purge(&sk->sk_receive_queue);
538 dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
539}
540
541static int pptp_create(struct net *net, struct socket *sock, int kern)
542{
543 int error = -ENOMEM;
544 struct sock *sk;
545 struct pppox_sock *po;
546 struct pptp_opt *opt;
547
548 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
549 if (!sk)
550 goto out;
551
552 sock_init_data(sock, sk);
553
554 sock->state = SS_UNCONNECTED;
555 sock->ops = &pptp_ops;
556
557 sk->sk_backlog_rcv = pptp_rcv_core;
558 sk->sk_state = PPPOX_NONE;
559 sk->sk_type = SOCK_STREAM;
560 sk->sk_family = PF_PPPOX;
561 sk->sk_protocol = PX_PROTO_PPTP;
562 sk->sk_destruct = pptp_sock_destruct;
563
564 po = pppox_sk(sk);
565 opt = &po->proto.pptp;
566
567 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
568 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
569
570 error = 0;
571out:
572 return error;
573}
574
575static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
576 unsigned long arg)
577{
578 struct sock *sk = chan->private;
579 struct pppox_sock *po = pppox_sk(sk);
580 struct pptp_opt *opt = &po->proto.pptp;
581 void __user *argp = (void __user *)arg;
582 int __user *p = argp;
583 int err, val;
584
585 err = -EFAULT;
586 switch (cmd) {
587 case PPPIOCGFLAGS:
588 val = opt->ppp_flags;
589 if (put_user(val, p))
590 break;
591 err = 0;
592 break;
593 case PPPIOCSFLAGS:
594 if (get_user(val, p))
595 break;
596 opt->ppp_flags = val & ~SC_RCV_BITS;
597 err = 0;
598 break;
599 default:
600 err = -ENOTTY;
601 }
602
603 return err;
604}
605
606static const struct ppp_channel_ops pptp_chan_ops = {
607 .start_xmit = pptp_xmit,
608 .ioctl = pptp_ppp_ioctl,
609};
610
611static struct proto pptp_sk_proto __read_mostly = {
612 .name = "PPTP",
613 .owner = THIS_MODULE,
614 .obj_size = sizeof(struct pppox_sock),
615};
616
617static const struct proto_ops pptp_ops = {
618 .family = AF_PPPOX,
619 .owner = THIS_MODULE,
620 .release = pptp_release,
621 .bind = pptp_bind,
622 .connect = pptp_connect,
623 .socketpair = sock_no_socketpair,
624 .accept = sock_no_accept,
625 .getname = pptp_getname,
626 .listen = sock_no_listen,
627 .shutdown = sock_no_shutdown,
628 .sendmsg = sock_no_sendmsg,
629 .recvmsg = sock_no_recvmsg,
630 .mmap = sock_no_mmap,
631 .ioctl = pppox_ioctl,
632#ifdef CONFIG_COMPAT
633 .compat_ioctl = pppox_compat_ioctl,
634#endif
635};
636
637static const struct pppox_proto pppox_pptp_proto = {
638 .create = pptp_create,
639 .owner = THIS_MODULE,
640};
641
642static const struct gre_protocol gre_pptp_protocol = {
643 .handler = pptp_rcv,
644};
645
646static int __init pptp_init_module(void)
647{
648 int err = 0;
649 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
650
651 callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
652 if (!callid_sock)
653 return -ENOMEM;
654
655 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
656 if (err) {
657 pr_err("PPTP: can't add gre protocol\n");
658 goto out_mem_free;
659 }
660
661 err = proto_register(&pptp_sk_proto, 0);
662 if (err) {
663 pr_err("PPTP: can't register sk_proto\n");
664 goto out_gre_del_protocol;
665 }
666
667 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
668 if (err) {
669 pr_err("PPTP: can't register pppox_proto\n");
670 goto out_unregister_sk_proto;
671 }
672
673 return 0;
674
675out_unregister_sk_proto:
676 proto_unregister(&pptp_sk_proto);
677out_gre_del_protocol:
678 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
679out_mem_free:
680 vfree(callid_sock);
681
682 return err;
683}
684
685static void __exit pptp_exit_module(void)
686{
687 unregister_pppox_proto(PX_PROTO_PPTP);
688 proto_unregister(&pptp_sk_proto);
689 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
690 vfree(callid_sock);
691}
692
693module_init(pptp_init_module);
694module_exit(pptp_exit_module);
695
696MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
697MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
698MODULE_LICENSE("GPL");
699MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);
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/netfilter.h>
32#include <linux/netfilter_ipv4.h>
33#include <linux/rcupdate.h>
34#include <linux/spinlock.h>
35
36#include <net/sock.h>
37#include <net/protocol.h>
38#include <net/ip.h>
39#include <net/icmp.h>
40#include <net/route.h>
41#include <net/gre.h>
42
43#include <linux/uaccess.h>
44
45#define PPTP_DRIVER_VERSION "0.8.5"
46
47#define MAX_CALLID 65535
48
49static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
50static struct pppox_sock __rcu **callid_sock;
51
52static DEFINE_SPINLOCK(chan_lock);
53
54static struct proto pptp_sk_proto __read_mostly;
55static const struct ppp_channel_ops pptp_chan_ops;
56static const struct proto_ops pptp_ops;
57
58#define PPP_LCP_ECHOREQ 0x09
59#define PPP_LCP_ECHOREP 0x0A
60#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
61
62#define MISSING_WINDOW 20
63#define WRAPPED(curseq, lastseq)\
64 ((((curseq) & 0xffffff00) == 0) &&\
65 (((lastseq) & 0xffffff00) == 0xffffff00))
66
67#define PPTP_GRE_PROTO 0x880B
68#define PPTP_GRE_VER 0x1
69
70#define PPTP_GRE_FLAG_C 0x80
71#define PPTP_GRE_FLAG_R 0x40
72#define PPTP_GRE_FLAG_K 0x20
73#define PPTP_GRE_FLAG_S 0x10
74#define PPTP_GRE_FLAG_A 0x80
75
76#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
77#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
78#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
79#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
80#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)
81
82#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
83struct pptp_gre_header {
84 u8 flags;
85 u8 ver;
86 __be16 protocol;
87 __be16 payload_len;
88 __be16 call_id;
89 __be32 seq;
90 __be32 ack;
91} __packed;
92
93static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
94{
95 struct pppox_sock *sock;
96 struct pptp_opt *opt;
97
98 rcu_read_lock();
99 sock = rcu_dereference(callid_sock[call_id]);
100 if (sock) {
101 opt = &sock->proto.pptp;
102 if (opt->dst_addr.sin_addr.s_addr != s_addr)
103 sock = NULL;
104 else
105 sock_hold(sk_pppox(sock));
106 }
107 rcu_read_unlock();
108
109 return sock;
110}
111
112static int lookup_chan_dst(u16 call_id, __be32 d_addr)
113{
114 struct pppox_sock *sock;
115 struct pptp_opt *opt;
116 int i;
117
118 rcu_read_lock();
119 i = 1;
120 for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
121 sock = rcu_dereference(callid_sock[i]);
122 if (!sock)
123 continue;
124 opt = &sock->proto.pptp;
125 if (opt->dst_addr.call_id == call_id &&
126 opt->dst_addr.sin_addr.s_addr == d_addr)
127 break;
128 }
129 rcu_read_unlock();
130
131 return i < MAX_CALLID;
132}
133
134static int add_chan(struct pppox_sock *sock)
135{
136 static int call_id;
137
138 spin_lock(&chan_lock);
139 if (!sock->proto.pptp.src_addr.call_id) {
140 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
141 if (call_id == MAX_CALLID) {
142 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
143 if (call_id == MAX_CALLID)
144 goto out_err;
145 }
146 sock->proto.pptp.src_addr.call_id = call_id;
147 } else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap))
148 goto out_err;
149
150 set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
151 rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], sock);
152 spin_unlock(&chan_lock);
153
154 return 0;
155
156out_err:
157 spin_unlock(&chan_lock);
158 return -1;
159}
160
161static void del_chan(struct pppox_sock *sock)
162{
163 spin_lock(&chan_lock);
164 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
165 RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
166 spin_unlock(&chan_lock);
167 synchronize_rcu();
168}
169
170static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
171{
172 struct sock *sk = (struct sock *) chan->private;
173 struct pppox_sock *po = pppox_sk(sk);
174 struct pptp_opt *opt = &po->proto.pptp;
175 struct pptp_gre_header *hdr;
176 unsigned int header_len = sizeof(*hdr);
177 struct flowi4 fl4;
178 int islcp;
179 int len;
180 unsigned char *data;
181 __u32 seq_recv;
182
183
184 struct rtable *rt;
185 struct net_device *tdev;
186 struct iphdr *iph;
187 int max_headroom;
188
189 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
190 goto tx_error;
191
192 rt = ip_route_output_ports(sock_net(sk), &fl4, NULL,
193 opt->dst_addr.sin_addr.s_addr,
194 opt->src_addr.sin_addr.s_addr,
195 0, 0, IPPROTO_GRE,
196 RT_TOS(0), 0);
197 if (IS_ERR(rt))
198 goto tx_error;
199
200 tdev = rt->dst.dev;
201
202 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
203
204 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
205 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
206 if (!new_skb) {
207 ip_rt_put(rt);
208 goto tx_error;
209 }
210 if (skb->sk)
211 skb_set_owner_w(new_skb, skb->sk);
212 consume_skb(skb);
213 skb = new_skb;
214 }
215
216 data = skb->data;
217 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
218
219 /* compress protocol field */
220 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
221 skb_pull(skb, 1);
222
223 /* Put in the address/control bytes if necessary */
224 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
225 data = skb_push(skb, 2);
226 data[0] = PPP_ALLSTATIONS;
227 data[1] = PPP_UI;
228 }
229
230 len = skb->len;
231
232 seq_recv = opt->seq_recv;
233
234 if (opt->ack_sent == seq_recv)
235 header_len -= sizeof(hdr->ack);
236
237 /* Push down and install GRE header */
238 skb_push(skb, header_len);
239 hdr = (struct pptp_gre_header *)(skb->data);
240
241 hdr->flags = PPTP_GRE_FLAG_K;
242 hdr->ver = PPTP_GRE_VER;
243 hdr->protocol = htons(PPTP_GRE_PROTO);
244 hdr->call_id = htons(opt->dst_addr.call_id);
245
246 hdr->flags |= PPTP_GRE_FLAG_S;
247 hdr->seq = htonl(++opt->seq_sent);
248 if (opt->ack_sent != seq_recv) {
249 /* send ack with this message */
250 hdr->ver |= PPTP_GRE_FLAG_A;
251 hdr->ack = htonl(seq_recv);
252 opt->ack_sent = seq_recv;
253 }
254 hdr->payload_len = htons(len);
255
256 /* Push down and install the IP header. */
257
258 skb_reset_transport_header(skb);
259 skb_push(skb, sizeof(*iph));
260 skb_reset_network_header(skb);
261 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
262 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
263
264 iph = ip_hdr(skb);
265 iph->version = 4;
266 iph->ihl = sizeof(struct iphdr) >> 2;
267 if (ip_dont_fragment(sk, &rt->dst))
268 iph->frag_off = htons(IP_DF);
269 else
270 iph->frag_off = 0;
271 iph->protocol = IPPROTO_GRE;
272 iph->tos = 0;
273 iph->daddr = fl4.daddr;
274 iph->saddr = fl4.saddr;
275 iph->ttl = ip4_dst_hoplimit(&rt->dst);
276 iph->tot_len = htons(skb->len);
277
278 skb_dst_drop(skb);
279 skb_dst_set(skb, &rt->dst);
280
281 nf_reset(skb);
282
283 skb->ip_summed = CHECKSUM_NONE;
284 ip_select_ident(skb, &rt->dst, NULL);
285 ip_send_check(iph);
286
287 ip_local_out(skb);
288 return 1;
289
290tx_error:
291 kfree_skb(skb);
292 return 1;
293}
294
295static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
296{
297 struct pppox_sock *po = pppox_sk(sk);
298 struct pptp_opt *opt = &po->proto.pptp;
299 int headersize, payload_len, seq;
300 __u8 *payload;
301 struct pptp_gre_header *header;
302
303 if (!(sk->sk_state & PPPOX_CONNECTED)) {
304 if (sock_queue_rcv_skb(sk, skb))
305 goto drop;
306 return NET_RX_SUCCESS;
307 }
308
309 header = (struct pptp_gre_header *)(skb->data);
310 headersize = sizeof(*header);
311
312 /* test if acknowledgement present */
313 if (PPTP_GRE_IS_A(header->ver)) {
314 __u32 ack;
315
316 if (!pskb_may_pull(skb, headersize))
317 goto drop;
318 header = (struct pptp_gre_header *)(skb->data);
319
320 /* ack in different place if S = 0 */
321 ack = PPTP_GRE_IS_S(header->flags) ? header->ack : header->seq;
322
323 ack = ntohl(ack);
324
325 if (ack > opt->ack_recv)
326 opt->ack_recv = ack;
327 /* also handle sequence number wrap-around */
328 if (WRAPPED(ack, opt->ack_recv))
329 opt->ack_recv = ack;
330 } else {
331 headersize -= sizeof(header->ack);
332 }
333 /* test if payload present */
334 if (!PPTP_GRE_IS_S(header->flags))
335 goto drop;
336
337 payload_len = ntohs(header->payload_len);
338 seq = ntohl(header->seq);
339
340 /* check for incomplete packet (length smaller than expected) */
341 if (!pskb_may_pull(skb, headersize + payload_len))
342 goto drop;
343
344 payload = skb->data + headersize;
345 /* check for expected sequence number */
346 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
347 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
348 (PPP_PROTOCOL(payload) == PPP_LCP) &&
349 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
350 goto allow_packet;
351 } else {
352 opt->seq_recv = seq;
353allow_packet:
354 skb_pull(skb, headersize);
355
356 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
357 /* chop off address/control */
358 if (skb->len < 3)
359 goto drop;
360 skb_pull(skb, 2);
361 }
362
363 if ((*skb->data) & 1) {
364 /* protocol is compressed */
365 skb_push(skb, 1)[0] = 0;
366 }
367
368 skb->ip_summed = CHECKSUM_NONE;
369 skb_set_network_header(skb, skb->head-skb->data);
370 ppp_input(&po->chan, skb);
371
372 return NET_RX_SUCCESS;
373 }
374drop:
375 kfree_skb(skb);
376 return NET_RX_DROP;
377}
378
379static int pptp_rcv(struct sk_buff *skb)
380{
381 struct pppox_sock *po;
382 struct pptp_gre_header *header;
383 struct iphdr *iph;
384
385 if (skb->pkt_type != PACKET_HOST)
386 goto drop;
387
388 if (!pskb_may_pull(skb, 12))
389 goto drop;
390
391 iph = ip_hdr(skb);
392
393 header = (struct pptp_gre_header *)skb->data;
394
395 if (ntohs(header->protocol) != PPTP_GRE_PROTO || /* PPTP-GRE protocol for PPTP */
396 PPTP_GRE_IS_C(header->flags) || /* flag C should be clear */
397 PPTP_GRE_IS_R(header->flags) || /* flag R should be clear */
398 !PPTP_GRE_IS_K(header->flags) || /* flag K should be set */
399 (header->flags&0xF) != 0) /* routing and recursion ctrl = 0 */
400 /* if invalid, discard this packet */
401 goto drop;
402
403 po = lookup_chan(htons(header->call_id), iph->saddr);
404 if (po) {
405 skb_dst_drop(skb);
406 nf_reset(skb);
407 return sk_receive_skb(sk_pppox(po), skb, 0);
408 }
409drop:
410 kfree_skb(skb);
411 return NET_RX_DROP;
412}
413
414static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
415 int sockaddr_len)
416{
417 struct sock *sk = sock->sk;
418 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
419 struct pppox_sock *po = pppox_sk(sk);
420 struct pptp_opt *opt = &po->proto.pptp;
421 int error = 0;
422
423 lock_sock(sk);
424
425 opt->src_addr = sp->sa_addr.pptp;
426 if (add_chan(po))
427 error = -EBUSY;
428
429 release_sock(sk);
430 return error;
431}
432
433static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
434 int sockaddr_len, int flags)
435{
436 struct sock *sk = sock->sk;
437 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
438 struct pppox_sock *po = pppox_sk(sk);
439 struct pptp_opt *opt = &po->proto.pptp;
440 struct rtable *rt;
441 struct flowi4 fl4;
442 int error = 0;
443
444 if (sp->sa_protocol != PX_PROTO_PPTP)
445 return -EINVAL;
446
447 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
448 return -EALREADY;
449
450 lock_sock(sk);
451 /* Check for already bound sockets */
452 if (sk->sk_state & PPPOX_CONNECTED) {
453 error = -EBUSY;
454 goto end;
455 }
456
457 /* Check for already disconnected sockets, on attempts to disconnect */
458 if (sk->sk_state & PPPOX_DEAD) {
459 error = -EALREADY;
460 goto end;
461 }
462
463 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
464 error = -EINVAL;
465 goto end;
466 }
467
468 po->chan.private = sk;
469 po->chan.ops = &pptp_chan_ops;
470
471 rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
472 opt->dst_addr.sin_addr.s_addr,
473 opt->src_addr.sin_addr.s_addr,
474 0, 0,
475 IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
476 if (IS_ERR(rt)) {
477 error = -EHOSTUNREACH;
478 goto end;
479 }
480 sk_setup_caps(sk, &rt->dst);
481
482 po->chan.mtu = dst_mtu(&rt->dst);
483 if (!po->chan.mtu)
484 po->chan.mtu = PPP_MRU;
485 ip_rt_put(rt);
486 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
487
488 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
489 error = ppp_register_channel(&po->chan);
490 if (error) {
491 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
492 goto end;
493 }
494
495 opt->dst_addr = sp->sa_addr.pptp;
496 sk->sk_state = PPPOX_CONNECTED;
497
498 end:
499 release_sock(sk);
500 return error;
501}
502
503static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
504 int *usockaddr_len, int peer)
505{
506 int len = sizeof(struct sockaddr_pppox);
507 struct sockaddr_pppox sp;
508
509 sp.sa_family = AF_PPPOX;
510 sp.sa_protocol = PX_PROTO_PPTP;
511 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
512
513 memcpy(uaddr, &sp, len);
514
515 *usockaddr_len = len;
516
517 return 0;
518}
519
520static int pptp_release(struct socket *sock)
521{
522 struct sock *sk = sock->sk;
523 struct pppox_sock *po;
524 struct pptp_opt *opt;
525 int error = 0;
526
527 if (!sk)
528 return 0;
529
530 lock_sock(sk);
531
532 if (sock_flag(sk, SOCK_DEAD)) {
533 release_sock(sk);
534 return -EBADF;
535 }
536
537 po = pppox_sk(sk);
538 opt = &po->proto.pptp;
539 del_chan(po);
540
541 pppox_unbind_sock(sk);
542 sk->sk_state = PPPOX_DEAD;
543
544 sock_orphan(sk);
545 sock->sk = NULL;
546
547 release_sock(sk);
548 sock_put(sk);
549
550 return error;
551}
552
553static void pptp_sock_destruct(struct sock *sk)
554{
555 if (!(sk->sk_state & PPPOX_DEAD)) {
556 del_chan(pppox_sk(sk));
557 pppox_unbind_sock(sk);
558 }
559 skb_queue_purge(&sk->sk_receive_queue);
560}
561
562static int pptp_create(struct net *net, struct socket *sock)
563{
564 int error = -ENOMEM;
565 struct sock *sk;
566 struct pppox_sock *po;
567 struct pptp_opt *opt;
568
569 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto);
570 if (!sk)
571 goto out;
572
573 sock_init_data(sock, sk);
574
575 sock->state = SS_UNCONNECTED;
576 sock->ops = &pptp_ops;
577
578 sk->sk_backlog_rcv = pptp_rcv_core;
579 sk->sk_state = PPPOX_NONE;
580 sk->sk_type = SOCK_STREAM;
581 sk->sk_family = PF_PPPOX;
582 sk->sk_protocol = PX_PROTO_PPTP;
583 sk->sk_destruct = pptp_sock_destruct;
584
585 po = pppox_sk(sk);
586 opt = &po->proto.pptp;
587
588 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
589 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
590
591 error = 0;
592out:
593 return error;
594}
595
596static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
597 unsigned long arg)
598{
599 struct sock *sk = (struct sock *) chan->private;
600 struct pppox_sock *po = pppox_sk(sk);
601 struct pptp_opt *opt = &po->proto.pptp;
602 void __user *argp = (void __user *)arg;
603 int __user *p = argp;
604 int err, val;
605
606 err = -EFAULT;
607 switch (cmd) {
608 case PPPIOCGFLAGS:
609 val = opt->ppp_flags;
610 if (put_user(val, p))
611 break;
612 err = 0;
613 break;
614 case PPPIOCSFLAGS:
615 if (get_user(val, p))
616 break;
617 opt->ppp_flags = val & ~SC_RCV_BITS;
618 err = 0;
619 break;
620 default:
621 err = -ENOTTY;
622 }
623
624 return err;
625}
626
627static const struct ppp_channel_ops pptp_chan_ops = {
628 .start_xmit = pptp_xmit,
629 .ioctl = pptp_ppp_ioctl,
630};
631
632static struct proto pptp_sk_proto __read_mostly = {
633 .name = "PPTP",
634 .owner = THIS_MODULE,
635 .obj_size = sizeof(struct pppox_sock),
636};
637
638static const struct proto_ops pptp_ops = {
639 .family = AF_PPPOX,
640 .owner = THIS_MODULE,
641 .release = pptp_release,
642 .bind = pptp_bind,
643 .connect = pptp_connect,
644 .socketpair = sock_no_socketpair,
645 .accept = sock_no_accept,
646 .getname = pptp_getname,
647 .poll = sock_no_poll,
648 .listen = sock_no_listen,
649 .shutdown = sock_no_shutdown,
650 .setsockopt = sock_no_setsockopt,
651 .getsockopt = sock_no_getsockopt,
652 .sendmsg = sock_no_sendmsg,
653 .recvmsg = sock_no_recvmsg,
654 .mmap = sock_no_mmap,
655 .ioctl = pppox_ioctl,
656};
657
658static const struct pppox_proto pppox_pptp_proto = {
659 .create = pptp_create,
660 .owner = THIS_MODULE,
661};
662
663static const struct gre_protocol gre_pptp_protocol = {
664 .handler = pptp_rcv,
665};
666
667static int __init pptp_init_module(void)
668{
669 int err = 0;
670 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
671
672 callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
673 if (!callid_sock)
674 return -ENOMEM;
675
676 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
677 if (err) {
678 pr_err("PPTP: can't add gre protocol\n");
679 goto out_mem_free;
680 }
681
682 err = proto_register(&pptp_sk_proto, 0);
683 if (err) {
684 pr_err("PPTP: can't register sk_proto\n");
685 goto out_gre_del_protocol;
686 }
687
688 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
689 if (err) {
690 pr_err("PPTP: can't register pppox_proto\n");
691 goto out_unregister_sk_proto;
692 }
693
694 return 0;
695
696out_unregister_sk_proto:
697 proto_unregister(&pptp_sk_proto);
698out_gre_del_protocol:
699 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
700out_mem_free:
701 vfree(callid_sock);
702
703 return err;
704}
705
706static void __exit pptp_exit_module(void)
707{
708 unregister_pppox_proto(PX_PROTO_PPTP);
709 proto_unregister(&pptp_sk_proto);
710 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
711 vfree(callid_sock);
712}
713
714module_init(pptp_init_module);
715module_exit(pptp_exit_module);
716
717MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
718MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
719MODULE_LICENSE("GPL");