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