2 * Point-to-Point Tunneling Protocol for Linux
4 * Authors: Dmitry Kozlov <xeb@mail.ru>
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.
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>
31 #include <linux/netfilter.h>
32 #include <linux/netfilter_ipv4.h>
33 #include <linux/rcupdate.h>
34 #include <linux/spinlock.h>
37 #include <net/protocol.h>
40 #include <net/route.h>
43 #include <linux/uaccess.h>
45 #define PPTP_DRIVER_VERSION "0.8.5"
47 #define MAX_CALLID 65535
49 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
50 static struct pppox_sock **callid_sock;
52 static DEFINE_SPINLOCK(chan_lock);
54 static struct proto pptp_sk_proto __read_mostly;
55 static const struct ppp_channel_ops pptp_chan_ops;
56 static const struct proto_ops pptp_ops;
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)
62 #define MISSING_WINDOW 20
63 #define WRAPPED(curseq, lastseq)\
64 ((((curseq) & 0xffffff00) == 0) &&\
65 (((lastseq) & 0xffffff00) == 0xffffff00))
67 #define PPTP_GRE_PROTO 0x880B
68 #define PPTP_GRE_VER 0x1
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
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)
82 #define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
83 struct pptp_gre_header {
93 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
95 struct pppox_sock *sock;
99 sock = rcu_dereference(callid_sock[call_id]);
101 opt = &sock->proto.pptp;
102 if (opt->dst_addr.sin_addr.s_addr != s_addr)
105 sock_hold(sk_pppox(sock));
112 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
114 struct pppox_sock *sock;
115 struct pptp_opt *opt;
119 for (i = find_next_bit(callid_bitmap, MAX_CALLID, 1); i < MAX_CALLID;
120 i = find_next_bit(callid_bitmap, MAX_CALLID, i + 1)) {
121 sock = rcu_dereference(callid_sock[i]);
124 opt = &sock->proto.pptp;
125 if (opt->dst_addr.call_id == call_id &&
126 opt->dst_addr.sin_addr.s_addr == d_addr)
131 return i < MAX_CALLID;
134 static int add_chan(struct pppox_sock *sock,
135 struct pptp_addr *sa)
139 spin_lock(&chan_lock);
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)
147 sa->call_id = call_id;
148 } else if (test_bit(sa->call_id, callid_bitmap)) {
152 sock->proto.pptp.src_addr = *sa;
153 set_bit(sa->call_id, callid_bitmap);
154 rcu_assign_pointer(callid_sock[sa->call_id], sock);
155 spin_unlock(&chan_lock);
160 spin_unlock(&chan_lock);
164 static void del_chan(struct pppox_sock *sock)
166 spin_lock(&chan_lock);
167 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
168 rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
169 spin_unlock(&chan_lock);
173 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
175 struct sock *sk = (struct sock *) chan->private;
176 struct pppox_sock *po = pppox_sk(sk);
177 struct pptp_opt *opt = &po->proto.pptp;
178 struct pptp_gre_header *hdr;
179 unsigned int header_len = sizeof(*hdr);
188 struct net_device *tdev;
192 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
195 rt = ip_route_output_ports(sock_net(sk), &fl4, NULL,
196 opt->dst_addr.sin_addr.s_addr,
197 opt->src_addr.sin_addr.s_addr,
205 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
207 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
208 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
214 skb_set_owner_w(new_skb, skb->sk);
220 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
222 /* compress protocol field */
223 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
226 /* Put in the address/control bytes if necessary */
227 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
228 data = skb_push(skb, 2);
229 data[0] = PPP_ALLSTATIONS;
235 seq_recv = opt->seq_recv;
237 if (opt->ack_sent == seq_recv)
238 header_len -= sizeof(hdr->ack);
240 /* Push down and install GRE header */
241 skb_push(skb, header_len);
242 hdr = (struct pptp_gre_header *)(skb->data);
244 hdr->flags = PPTP_GRE_FLAG_K;
245 hdr->ver = PPTP_GRE_VER;
246 hdr->protocol = htons(PPTP_GRE_PROTO);
247 hdr->call_id = htons(opt->dst_addr.call_id);
249 hdr->flags |= PPTP_GRE_FLAG_S;
250 hdr->seq = htonl(++opt->seq_sent);
251 if (opt->ack_sent != seq_recv) {
252 /* send ack with this message */
253 hdr->ver |= PPTP_GRE_FLAG_A;
254 hdr->ack = htonl(seq_recv);
255 opt->ack_sent = seq_recv;
257 hdr->payload_len = htons(len);
259 /* Push down and install the IP header. */
261 skb_reset_transport_header(skb);
262 skb_push(skb, sizeof(*iph));
263 skb_reset_network_header(skb);
264 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
265 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
269 iph->ihl = sizeof(struct iphdr) >> 2;
270 if (ip_dont_fragment(sk, &rt->dst))
271 iph->frag_off = htons(IP_DF);
274 iph->protocol = IPPROTO_GRE;
276 iph->daddr = fl4.daddr;
277 iph->saddr = fl4.saddr;
278 iph->ttl = ip4_dst_hoplimit(&rt->dst);
279 iph->tot_len = htons(skb->len);
282 skb_dst_set(skb, &rt->dst);
286 skb->ip_summed = CHECKSUM_NONE;
287 ip_select_ident(skb, NULL);
298 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
300 struct pppox_sock *po = pppox_sk(sk);
301 struct pptp_opt *opt = &po->proto.pptp;
302 int headersize, payload_len, seq;
304 struct pptp_gre_header *header;
306 if (!(sk->sk_state & PPPOX_CONNECTED)) {
307 if (sock_queue_rcv_skb(sk, skb))
309 return NET_RX_SUCCESS;
312 header = (struct pptp_gre_header *)(skb->data);
313 headersize = sizeof(*header);
315 /* test if acknowledgement present */
316 if (PPTP_GRE_IS_A(header->ver)) {
319 if (!pskb_may_pull(skb, headersize))
321 header = (struct pptp_gre_header *)(skb->data);
323 /* ack in different place if S = 0 */
324 ack = PPTP_GRE_IS_S(header->flags) ? header->ack : header->seq;
328 if (ack > opt->ack_recv)
330 /* also handle sequence number wrap-around */
331 if (WRAPPED(ack, opt->ack_recv))
334 headersize -= sizeof(header->ack);
336 /* test if payload present */
337 if (!PPTP_GRE_IS_S(header->flags))
340 payload_len = ntohs(header->payload_len);
341 seq = ntohl(header->seq);
343 /* check for incomplete packet (length smaller than expected) */
344 if (!pskb_may_pull(skb, headersize + payload_len))
347 payload = skb->data + headersize;
348 /* check for expected sequence number */
349 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
350 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
351 (PPP_PROTOCOL(payload) == PPP_LCP) &&
352 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
357 skb_pull(skb, headersize);
359 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
360 /* chop off address/control */
366 if ((*skb->data) & 1) {
367 /* protocol is compressed */
368 skb_push(skb, 1)[0] = 0;
371 skb->ip_summed = CHECKSUM_NONE;
372 skb_set_network_header(skb, skb->head-skb->data);
373 ppp_input(&po->chan, skb);
375 return NET_RX_SUCCESS;
382 static int pptp_rcv(struct sk_buff *skb)
384 struct pppox_sock *po;
385 struct pptp_gre_header *header;
388 if (skb->pkt_type != PACKET_HOST)
391 if (!pskb_may_pull(skb, 12))
396 header = (struct pptp_gre_header *)skb->data;
398 if (ntohs(header->protocol) != PPTP_GRE_PROTO || /* PPTP-GRE protocol for PPTP */
399 PPTP_GRE_IS_C(header->flags) || /* flag C should be clear */
400 PPTP_GRE_IS_R(header->flags) || /* flag R should be clear */
401 !PPTP_GRE_IS_K(header->flags) || /* flag K should be set */
402 (header->flags&0xF) != 0) /* routing and recursion ctrl = 0 */
403 /* if invalid, discard this packet */
406 po = lookup_chan(htons(header->call_id), iph->saddr);
410 return sk_receive_skb(sk_pppox(po), skb, 0);
417 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
420 struct sock *sk = sock->sk;
421 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
422 struct pppox_sock *po = pppox_sk(sk);
425 if (sockaddr_len < sizeof(struct sockaddr_pppox))
430 if (sk->sk_state & PPPOX_DEAD) {
435 if (sk->sk_state & PPPOX_BOUND) {
440 if (add_chan(po, &sp->sa_addr.pptp))
443 sk->sk_state |= PPPOX_BOUND;
450 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
451 int sockaddr_len, int flags)
453 struct sock *sk = sock->sk;
454 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
455 struct pppox_sock *po = pppox_sk(sk);
456 struct pptp_opt *opt = &po->proto.pptp;
461 if (sockaddr_len < sizeof(struct sockaddr_pppox))
464 if (sp->sa_protocol != PX_PROTO_PPTP)
467 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
471 /* Check for already bound sockets */
472 if (sk->sk_state & PPPOX_CONNECTED) {
477 /* Check for already disconnected sockets, on attempts to disconnect */
478 if (sk->sk_state & PPPOX_DEAD) {
483 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
488 po->chan.private = sk;
489 po->chan.ops = &pptp_chan_ops;
491 rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
492 opt->dst_addr.sin_addr.s_addr,
493 opt->src_addr.sin_addr.s_addr,
495 IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
497 error = -EHOSTUNREACH;
500 sk_setup_caps(sk, &rt->dst);
502 po->chan.mtu = dst_mtu(&rt->dst);
504 po->chan.mtu = PPP_MTU;
506 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
508 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
509 error = ppp_register_channel(&po->chan);
511 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
515 opt->dst_addr = sp->sa_addr.pptp;
516 sk->sk_state |= PPPOX_CONNECTED;
523 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
524 int *usockaddr_len, int peer)
526 int len = sizeof(struct sockaddr_pppox);
527 struct sockaddr_pppox sp;
529 sp.sa_family = AF_PPPOX;
530 sp.sa_protocol = PX_PROTO_PPTP;
531 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
533 memcpy(uaddr, &sp, len);
535 *usockaddr_len = len;
540 static int pptp_release(struct socket *sock)
542 struct sock *sk = sock->sk;
543 struct pppox_sock *po;
544 struct pptp_opt *opt;
552 if (sock_flag(sk, SOCK_DEAD)) {
558 opt = &po->proto.pptp;
561 pppox_unbind_sock(sk);
562 sk->sk_state = PPPOX_DEAD;
573 static void pptp_sock_destruct(struct sock *sk)
575 if (!(sk->sk_state & PPPOX_DEAD)) {
576 del_chan(pppox_sk(sk));
577 pppox_unbind_sock(sk);
579 skb_queue_purge(&sk->sk_receive_queue);
582 static int pptp_create(struct net *net, struct socket *sock)
586 struct pppox_sock *po;
587 struct pptp_opt *opt;
589 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto);
593 sock_init_data(sock, sk);
595 sock->state = SS_UNCONNECTED;
596 sock->ops = &pptp_ops;
598 sk->sk_backlog_rcv = pptp_rcv_core;
599 sk->sk_state = PPPOX_NONE;
600 sk->sk_type = SOCK_STREAM;
601 sk->sk_family = PF_PPPOX;
602 sk->sk_protocol = PX_PROTO_PPTP;
603 sk->sk_destruct = pptp_sock_destruct;
606 opt = &po->proto.pptp;
608 opt->seq_sent = 0; opt->seq_recv = 0;
609 opt->ack_recv = 0; opt->ack_sent = 0;
616 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
619 struct sock *sk = (struct sock *) chan->private;
620 struct pppox_sock *po = pppox_sk(sk);
621 struct pptp_opt *opt = &po->proto.pptp;
622 void __user *argp = (void __user *)arg;
623 int __user *p = argp;
629 val = opt->ppp_flags;
630 if (put_user(val, p))
635 if (get_user(val, p))
637 opt->ppp_flags = val & ~SC_RCV_BITS;
647 static const struct ppp_channel_ops pptp_chan_ops = {
648 .start_xmit = pptp_xmit,
649 .ioctl = pptp_ppp_ioctl,
652 static struct proto pptp_sk_proto __read_mostly = {
654 .owner = THIS_MODULE,
655 .obj_size = sizeof(struct pppox_sock),
658 static const struct proto_ops pptp_ops = {
660 .owner = THIS_MODULE,
661 .release = pptp_release,
663 .connect = pptp_connect,
664 .socketpair = sock_no_socketpair,
665 .accept = sock_no_accept,
666 .getname = pptp_getname,
667 .poll = sock_no_poll,
668 .listen = sock_no_listen,
669 .shutdown = sock_no_shutdown,
670 .setsockopt = sock_no_setsockopt,
671 .getsockopt = sock_no_getsockopt,
672 .sendmsg = sock_no_sendmsg,
673 .recvmsg = sock_no_recvmsg,
674 .mmap = sock_no_mmap,
675 .ioctl = pppox_ioctl,
678 static const struct pppox_proto pppox_pptp_proto = {
679 .create = pptp_create,
680 .owner = THIS_MODULE,
683 static const struct gre_protocol gre_pptp_protocol = {
687 static int __init pptp_init_module(void)
690 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
692 callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
694 pr_err("PPTP: cann't allocate memory\n");
698 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
700 pr_err("PPTP: can't add gre protocol\n");
704 err = proto_register(&pptp_sk_proto, 0);
706 pr_err("PPTP: can't register sk_proto\n");
707 goto out_gre_del_protocol;
710 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
712 pr_err("PPTP: can't register pppox_proto\n");
713 goto out_unregister_sk_proto;
718 out_unregister_sk_proto:
719 proto_unregister(&pptp_sk_proto);
720 out_gre_del_protocol:
721 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
728 static void __exit pptp_exit_module(void)
730 unregister_pppox_proto(PX_PROTO_PPTP);
731 proto_unregister(&pptp_sk_proto);
732 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
736 module_init(pptp_init_module);
737 module_exit(pptp_exit_module);
739 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
740 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
741 MODULE_LICENSE("GPL");