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13#include <linux/string.h>
14#include <linux/module.h>
15#include <linux/kernel.h>
16#include <linux/slab.h>
17#include <linux/errno.h>
18#include <linux/netdevice.h>
19#include <linux/net.h>
20#include <linux/skbuff.h>
21#include <linux/vmalloc.h>
22#include <linux/init.h>
23#include <linux/ppp_channel.h>
24#include <linux/ppp_defs.h>
25#include <linux/if_pppox.h>
26#include <linux/if_ppp.h>
27#include <linux/notifier.h>
28#include <linux/file.h>
29#include <linux/in.h>
30#include <linux/ip.h>
31#include <linux/netfilter.h>
32#include <linux/netfilter_ipv4.h>
33#include <linux/version.h>
34#include <linux/rcupdate.h>
35#include <linux/spinlock.h>
36
37#include <net/sock.h>
38#include <net/protocol.h>
39#include <net/ip.h>
40#include <net/icmp.h>
41#include <net/route.h>
42#include <net/gre.h>
43
44#include <linux/uaccess.h>
45
46#define PPTP_DRIVER_VERSION "0.8.5"
47
48#define MAX_CALLID 65535
49
50static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
51static struct pppox_sock **callid_sock;
52
53static DEFINE_SPINLOCK(chan_lock);
54
55static struct proto pptp_sk_proto __read_mostly;
56static const struct ppp_channel_ops pptp_chan_ops;
57static const struct proto_ops pptp_ops;
58
59#define PPP_LCP_ECHOREQ 0x09
60#define PPP_LCP_ECHOREP 0x0A
61#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
62
63#define MISSING_WINDOW 20
64#define WRAPPED(curseq, lastseq)\
65 ((((curseq) & 0xffffff00) == 0) &&\
66 (((lastseq) & 0xffffff00) == 0xffffff00))
67
68#define PPTP_GRE_PROTO 0x880B
69#define PPTP_GRE_VER 0x1
70
71#define PPTP_GRE_FLAG_C 0x80
72#define PPTP_GRE_FLAG_R 0x40
73#define PPTP_GRE_FLAG_K 0x20
74#define PPTP_GRE_FLAG_S 0x10
75#define PPTP_GRE_FLAG_A 0x80
76
77#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
78#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
79#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
80#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
81#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)
82
83#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
84struct pptp_gre_header {
85 u8 flags;
86 u8 ver;
87 u16 protocol;
88 u16 payload_len;
89 u16 call_id;
90 u32 seq;
91 u32 ack;
92} __packed;
93
94static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
95{
96 struct pppox_sock *sock;
97 struct pptp_opt *opt;
98
99 rcu_read_lock();
100 sock = rcu_dereference(callid_sock[call_id]);
101 if (sock) {
102 opt = &sock->proto.pptp;
103 if (opt->dst_addr.sin_addr.s_addr != s_addr)
104 sock = NULL;
105 else
106 sock_hold(sk_pppox(sock));
107 }
108 rcu_read_unlock();
109
110 return sock;
111}
112
113static int lookup_chan_dst(u16 call_id, __be32 d_addr)
114{
115 struct pppox_sock *sock;
116 struct pptp_opt *opt;
117 int i;
118
119 rcu_read_lock();
120 for (i = find_next_bit(callid_bitmap, MAX_CALLID, 1); i < MAX_CALLID;
121 i = find_next_bit(callid_bitmap, MAX_CALLID, i + 1)) {
122 sock = rcu_dereference(callid_sock[i]);
123 if (!sock)
124 continue;
125 opt = &sock->proto.pptp;
126 if (opt->dst_addr.call_id == call_id &&
127 opt->dst_addr.sin_addr.s_addr == d_addr)
128 break;
129 }
130 rcu_read_unlock();
131
132 return i < MAX_CALLID;
133}
134
135static int add_chan(struct pppox_sock *sock)
136{
137 static int call_id;
138
139 spin_lock(&chan_lock);
140 if (!sock->proto.pptp.src_addr.call_id) {
141 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
142 if (call_id == MAX_CALLID) {
143 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
144 if (call_id == MAX_CALLID)
145 goto out_err;
146 }
147 sock->proto.pptp.src_addr.call_id = call_id;
148 } else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap))
149 goto out_err;
150
151 set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
152 rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], sock);
153 spin_unlock(&chan_lock);
154
155 return 0;
156
157out_err:
158 spin_unlock(&chan_lock);
159 return -1;
160}
161
162static void del_chan(struct pppox_sock *sock)
163{
164 spin_lock(&chan_lock);
165 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
166 rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
167 spin_unlock(&chan_lock);
168 synchronize_rcu();
169}
170
171static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
172{
173 struct sock *sk = (struct sock *) chan->private;
174 struct pppox_sock *po = pppox_sk(sk);
175 struct pptp_opt *opt = &po->proto.pptp;
176 struct pptp_gre_header *hdr;
177 unsigned int header_len = sizeof(*hdr);
178 int err = 0;
179 int islcp;
180 int len;
181 unsigned char *data;
182 __u32 seq_recv;
183
184
185 struct rtable *rt;
186 struct net_device *tdev;
187 struct iphdr *iph;
188 int max_headroom;
189
190 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
191 goto tx_error;
192
193 {
194 struct flowi fl = { .oif = 0,
195 .nl_u = {
196 .ip4_u = {
197 .daddr = opt->dst_addr.sin_addr.s_addr,
198 .saddr = opt->src_addr.sin_addr.s_addr,
199 .tos = RT_TOS(0) } },
200 .proto = IPPROTO_GRE };
201 err = ip_route_output_key(&init_net, &rt, &fl);
202 if (err)
203 goto tx_error;
204 }
205 tdev = rt->dst.dev;
206
207 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
208
209 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
210 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
211 if (!new_skb) {
212 ip_rt_put(rt);
213 goto tx_error;
214 }
215 if (skb->sk)
216 skb_set_owner_w(new_skb, skb->sk);
217 kfree_skb(skb);
218 skb = new_skb;
219 }
220
221 data = skb->data;
222 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
223
224
225 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
226 skb_pull(skb, 1);
227
228
229 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
230 data = skb_push(skb, 2);
231 data[0] = PPP_ALLSTATIONS;
232 data[1] = PPP_UI;
233 }
234
235 len = skb->len;
236
237 seq_recv = opt->seq_recv;
238
239 if (opt->ack_sent == seq_recv)
240 header_len -= sizeof(hdr->ack);
241
242
243 skb_push(skb, header_len);
244 hdr = (struct pptp_gre_header *)(skb->data);
245
246 hdr->flags = PPTP_GRE_FLAG_K;
247 hdr->ver = PPTP_GRE_VER;
248 hdr->protocol = htons(PPTP_GRE_PROTO);
249 hdr->call_id = htons(opt->dst_addr.call_id);
250
251 hdr->flags |= PPTP_GRE_FLAG_S;
252 hdr->seq = htonl(++opt->seq_sent);
253 if (opt->ack_sent != seq_recv) {
254
255 hdr->ver |= PPTP_GRE_FLAG_A;
256 hdr->ack = htonl(seq_recv);
257 opt->ack_sent = seq_recv;
258 }
259 hdr->payload_len = htons(len);
260
261
262
263 skb_reset_transport_header(skb);
264 skb_push(skb, sizeof(*iph));
265 skb_reset_network_header(skb);
266 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
267 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
268
269 iph = ip_hdr(skb);
270 iph->version = 4;
271 iph->ihl = sizeof(struct iphdr) >> 2;
272 if (ip_dont_fragment(sk, &rt->dst))
273 iph->frag_off = htons(IP_DF);
274 else
275 iph->frag_off = 0;
276 iph->protocol = IPPROTO_GRE;
277 iph->tos = 0;
278 iph->daddr = rt->rt_dst;
279 iph->saddr = rt->rt_src;
280 iph->ttl = ip4_dst_hoplimit(&rt->dst);
281 iph->tot_len = htons(skb->len);
282
283 skb_dst_drop(skb);
284 skb_dst_set(skb, &rt->dst);
285
286 nf_reset(skb);
287
288 skb->ip_summed = CHECKSUM_NONE;
289 ip_select_ident(iph, &rt->dst, NULL);
290 ip_send_check(iph);
291
292 ip_local_out(skb);
293
294tx_error:
295 return 1;
296}
297
298static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
299{
300 struct pppox_sock *po = pppox_sk(sk);
301 struct pptp_opt *opt = &po->proto.pptp;
302 int headersize, payload_len, seq;
303 __u8 *payload;
304 struct pptp_gre_header *header;
305
306 if (!(sk->sk_state & PPPOX_CONNECTED)) {
307 if (sock_queue_rcv_skb(sk, skb))
308 goto drop;
309 return NET_RX_SUCCESS;
310 }
311
312 header = (struct pptp_gre_header *)(skb->data);
313
314
315 if (PPTP_GRE_IS_A(header->ver)) {
316 __u32 ack = (PPTP_GRE_IS_S(header->flags)) ?
317 header->ack : header->seq;
318
319 ack = ntohl(ack);
320
321 if (ack > opt->ack_recv)
322 opt->ack_recv = ack;
323
324 if (WRAPPED(ack, opt->ack_recv))
325 opt->ack_recv = ack;
326 }
327
328
329 if (!PPTP_GRE_IS_S(header->flags))
330 goto drop;
331
332 headersize = sizeof(*header);
333 payload_len = ntohs(header->payload_len);
334 seq = ntohl(header->seq);
335
336
337 if (!PPTP_GRE_IS_A(header->ver))
338 headersize -= sizeof(header->ack);
339
340 if (skb->len - headersize < payload_len)
341 goto drop;
342
343 payload = skb->data + headersize;
344
345 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
346 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
347 (PPP_PROTOCOL(payload) == PPP_LCP) &&
348 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
349 goto allow_packet;
350 } else {
351 opt->seq_recv = seq;
352allow_packet:
353 skb_pull(skb, headersize);
354
355 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
356
357 if (skb->len < 3)
358 goto drop;
359 skb_pull(skb, 2);
360 }
361
362 if ((*skb->data) & 1) {
363
364 skb_push(skb, 1)[0] = 0;
365 }
366
367 skb->ip_summed = CHECKSUM_NONE;
368 skb_set_network_header(skb, skb->head-skb->data);
369 ppp_input(&po->chan, skb);
370
371 return NET_RX_SUCCESS;
372 }
373drop:
374 kfree_skb(skb);
375 return NET_RX_DROP;
376}
377
378static int pptp_rcv(struct sk_buff *skb)
379{
380 struct pppox_sock *po;
381 struct pptp_gre_header *header;
382 struct iphdr *iph;
383
384 if (skb->pkt_type != PACKET_HOST)
385 goto drop;
386
387 if (!pskb_may_pull(skb, 12))
388 goto drop;
389
390 iph = ip_hdr(skb);
391
392 header = (struct pptp_gre_header *)skb->data;
393
394 if (ntohs(header->protocol) != PPTP_GRE_PROTO ||
395 PPTP_GRE_IS_C(header->flags) ||
396 PPTP_GRE_IS_R(header->flags) ||
397 !PPTP_GRE_IS_K(header->flags) ||
398 (header->flags&0xF) != 0)
399
400 goto drop;
401
402 po = lookup_chan(htons(header->call_id), iph->saddr);
403 if (po) {
404 skb_dst_drop(skb);
405 nf_reset(skb);
406 return sk_receive_skb(sk_pppox(po), skb, 0);
407 }
408drop:
409 kfree_skb(skb);
410 return NET_RX_DROP;
411}
412
413static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
414 int sockaddr_len)
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 int error = 0;
421
422 lock_sock(sk);
423
424 opt->src_addr = sp->sa_addr.pptp;
425 if (add_chan(po)) {
426 release_sock(sk);
427 error = -EBUSY;
428 }
429
430 release_sock(sk);
431 return error;
432}
433
434static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
435 int sockaddr_len, int flags)
436{
437 struct sock *sk = sock->sk;
438 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
439 struct pppox_sock *po = pppox_sk(sk);
440 struct pptp_opt *opt = &po->proto.pptp;
441 struct rtable *rt;
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
452 if (sk->sk_state & PPPOX_CONNECTED) {
453 error = -EBUSY;
454 goto end;
455 }
456
457
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 {
472 struct flowi fl = {
473 .nl_u = {
474 .ip4_u = {
475 .daddr = opt->dst_addr.sin_addr.s_addr,
476 .saddr = opt->src_addr.sin_addr.s_addr,
477 .tos = RT_CONN_FLAGS(sk) } },
478 .proto = IPPROTO_GRE };
479 security_sk_classify_flow(sk, &fl);
480 if (ip_route_output_key(&init_net, &rt, &fl)) {
481 error = -EHOSTUNREACH;
482 goto end;
483 }
484 sk_setup_caps(sk, &rt->dst);
485 }
486 po->chan.mtu = dst_mtu(&rt->dst);
487 if (!po->chan.mtu)
488 po->chan.mtu = PPP_MTU;
489 ip_rt_put(rt);
490 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
491
492 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
493 error = ppp_register_channel(&po->chan);
494 if (error) {
495 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
496 goto end;
497 }
498
499 opt->dst_addr = sp->sa_addr.pptp;
500 sk->sk_state = PPPOX_CONNECTED;
501
502 end:
503 release_sock(sk);
504 return error;
505}
506
507static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
508 int *usockaddr_len, int peer)
509{
510 int len = sizeof(struct sockaddr_pppox);
511 struct sockaddr_pppox sp;
512
513 sp.sa_family = AF_PPPOX;
514 sp.sa_protocol = PX_PROTO_PPTP;
515 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
516
517 memcpy(uaddr, &sp, len);
518
519 *usockaddr_len = len;
520
521 return 0;
522}
523
524static int pptp_release(struct socket *sock)
525{
526 struct sock *sk = sock->sk;
527 struct pppox_sock *po;
528 struct pptp_opt *opt;
529 int error = 0;
530
531 if (!sk)
532 return 0;
533
534 lock_sock(sk);
535
536 if (sock_flag(sk, SOCK_DEAD)) {
537 release_sock(sk);
538 return -EBADF;
539 }
540
541 po = pppox_sk(sk);
542 opt = &po->proto.pptp;
543 del_chan(po);
544
545 pppox_unbind_sock(sk);
546 sk->sk_state = PPPOX_DEAD;
547
548 sock_orphan(sk);
549 sock->sk = NULL;
550
551 release_sock(sk);
552 sock_put(sk);
553
554 return error;
555}
556
557static void pptp_sock_destruct(struct sock *sk)
558{
559 if (!(sk->sk_state & PPPOX_DEAD)) {
560 del_chan(pppox_sk(sk));
561 pppox_unbind_sock(sk);
562 }
563 skb_queue_purge(&sk->sk_receive_queue);
564}
565
566static int pptp_create(struct net *net, struct socket *sock)
567{
568 int error = -ENOMEM;
569 struct sock *sk;
570 struct pppox_sock *po;
571 struct pptp_opt *opt;
572
573 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto);
574 if (!sk)
575 goto out;
576
577 sock_init_data(sock, sk);
578
579 sock->state = SS_UNCONNECTED;
580 sock->ops = &pptp_ops;
581
582 sk->sk_backlog_rcv = pptp_rcv_core;
583 sk->sk_state = PPPOX_NONE;
584 sk->sk_type = SOCK_STREAM;
585 sk->sk_family = PF_PPPOX;
586 sk->sk_protocol = PX_PROTO_PPTP;
587 sk->sk_destruct = pptp_sock_destruct;
588
589 po = pppox_sk(sk);
590 opt = &po->proto.pptp;
591
592 opt->seq_sent = 0; opt->seq_recv = 0;
593 opt->ack_recv = 0; opt->ack_sent = 0;
594
595 error = 0;
596out:
597 return error;
598}
599
600static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
601 unsigned long arg)
602{
603 struct sock *sk = (struct sock *) chan->private;
604 struct pppox_sock *po = pppox_sk(sk);
605 struct pptp_opt *opt = &po->proto.pptp;
606 void __user *argp = (void __user *)arg;
607 int __user *p = argp;
608 int err, val;
609
610 err = -EFAULT;
611 switch (cmd) {
612 case PPPIOCGFLAGS:
613 val = opt->ppp_flags;
614 if (put_user(val, p))
615 break;
616 err = 0;
617 break;
618 case PPPIOCSFLAGS:
619 if (get_user(val, p))
620 break;
621 opt->ppp_flags = val & ~SC_RCV_BITS;
622 err = 0;
623 break;
624 default:
625 err = -ENOTTY;
626 }
627
628 return err;
629}
630
631static const struct ppp_channel_ops pptp_chan_ops = {
632 .start_xmit = pptp_xmit,
633 .ioctl = pptp_ppp_ioctl,
634};
635
636static struct proto pptp_sk_proto __read_mostly = {
637 .name = "PPTP",
638 .owner = THIS_MODULE,
639 .obj_size = sizeof(struct pppox_sock),
640};
641
642static const struct proto_ops pptp_ops = {
643 .family = AF_PPPOX,
644 .owner = THIS_MODULE,
645 .release = pptp_release,
646 .bind = pptp_bind,
647 .connect = pptp_connect,
648 .socketpair = sock_no_socketpair,
649 .accept = sock_no_accept,
650 .getname = pptp_getname,
651 .poll = sock_no_poll,
652 .listen = sock_no_listen,
653 .shutdown = sock_no_shutdown,
654 .setsockopt = sock_no_setsockopt,
655 .getsockopt = sock_no_getsockopt,
656 .sendmsg = sock_no_sendmsg,
657 .recvmsg = sock_no_recvmsg,
658 .mmap = sock_no_mmap,
659 .ioctl = pppox_ioctl,
660};
661
662static const struct pppox_proto pppox_pptp_proto = {
663 .create = pptp_create,
664 .owner = THIS_MODULE,
665};
666
667static const struct gre_protocol gre_pptp_protocol = {
668 .handler = pptp_rcv,
669};
670
671static int __init pptp_init_module(void)
672{
673 int err = 0;
674 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
675
676 callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
677 if (!callid_sock) {
678 pr_err("PPTP: cann't allocate memory\n");
679 return -ENOMEM;
680 }
681
682 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
683 if (err) {
684 pr_err("PPTP: can't add gre protocol\n");
685 goto out_mem_free;
686 }
687
688 err = proto_register(&pptp_sk_proto, 0);
689 if (err) {
690 pr_err("PPTP: can't register sk_proto\n");
691 goto out_gre_del_protocol;
692 }
693
694 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
695 if (err) {
696 pr_err("PPTP: can't register pppox_proto\n");
697 goto out_unregister_sk_proto;
698 }
699
700 return 0;
701
702out_unregister_sk_proto:
703 proto_unregister(&pptp_sk_proto);
704out_gre_del_protocol:
705 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
706out_mem_free:
707 vfree(callid_sock);
708
709 return err;
710}
711
712static void __exit pptp_exit_module(void)
713{
714 unregister_pppox_proto(PX_PROTO_PPTP);
715 proto_unregister(&pptp_sk_proto);
716 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
717 vfree(callid_sock);
718}
719
720module_init(pptp_init_module);
721module_exit(pptp_exit_module);
722
723MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
724MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
725MODULE_LICENSE("GPL");
726
