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/ppp-ioctl.h>
27 #include <linux/notifier.h>
28 #include <linux/file.h>
31 #include <linux/rcupdate.h>
32 #include <linux/spinlock.h>
35 #include <net/protocol.h>
38 #include <net/route.h>
42 #include <linux/uaccess.h>
44 #define PPTP_DRIVER_VERSION "0.8.5"
46 #define MAX_CALLID 65535
48 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
49 static struct pppox_sock __rcu **callid_sock;
51 static DEFINE_SPINLOCK(chan_lock);
53 static struct proto pptp_sk_proto __read_mostly;
54 static const struct ppp_channel_ops pptp_chan_ops;
55 static const struct proto_ops pptp_ops;
57 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
59 struct pppox_sock *sock;
63 sock = rcu_dereference(callid_sock[call_id]);
65 opt = &sock->proto.pptp;
66 if (opt->dst_addr.sin_addr.s_addr != s_addr)
69 sock_hold(sk_pppox(sock));
76 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
78 struct pppox_sock *sock;
84 for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
85 sock = rcu_dereference(callid_sock[i]);
88 opt = &sock->proto.pptp;
89 if (opt->dst_addr.call_id == call_id &&
90 opt->dst_addr.sin_addr.s_addr == d_addr)
95 return i < MAX_CALLID;
98 static int add_chan(struct pppox_sock *sock,
103 spin_lock(&chan_lock);
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)
111 sa->call_id = call_id;
112 } else if (test_bit(sa->call_id, callid_bitmap)) {
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);
124 spin_unlock(&chan_lock);
128 static void del_chan(struct pppox_sock *sock)
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);
136 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
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);
152 struct net_device *tdev;
156 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
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,
169 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
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);
178 skb_set_owner_w(new_skb, skb->sk);
184 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
186 /* compress protocol field */
187 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
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;
199 seq_recv = opt->seq_recv;
201 if (opt->ack_sent == seq_recv)
202 header_len -= sizeof(hdr->ack);
204 /* Push down and install GRE header */
205 skb_push(skb, header_len);
206 hdr = (struct pptp_gre_header *)(skb->data);
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);
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;
219 hdr->payload_len = htons(len);
221 /* Push down and install the IP header. */
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);
231 iph->ihl = sizeof(struct iphdr) >> 2;
232 if (ip_dont_fragment(sk, &rt->dst))
233 iph->frag_off = htons(IP_DF);
236 iph->protocol = IPPROTO_GRE;
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);
244 skb_dst_set(skb, &rt->dst);
248 skb->ip_summed = CHECKSUM_NONE;
249 ip_select_ident(net, skb, NULL);
252 ip_local_out(net, skb->sk, skb);
260 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
262 struct pppox_sock *po = pppox_sk(sk);
263 struct pptp_opt *opt = &po->proto.pptp;
264 int headersize, payload_len, seq;
266 struct pptp_gre_header *header;
268 if (!(sk->sk_state & PPPOX_CONNECTED)) {
269 if (sock_queue_rcv_skb(sk, skb))
271 return NET_RX_SUCCESS;
274 header = (struct pptp_gre_header *)(skb->data);
275 headersize = sizeof(*header);
277 /* test if acknowledgement present */
278 if (GRE_IS_ACK(header->gre_hd.flags)) {
281 if (!pskb_may_pull(skb, headersize))
283 header = (struct pptp_gre_header *)(skb->data);
285 /* ack in different place if S = 0 */
286 ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
290 if (ack > opt->ack_recv)
292 /* also handle sequence number wrap-around */
293 if (WRAPPED(ack, opt->ack_recv))
296 headersize -= sizeof(header->ack);
298 /* test if payload present */
299 if (!GRE_IS_SEQ(header->gre_hd.flags))
302 payload_len = ntohs(header->payload_len);
303 seq = ntohl(header->seq);
305 /* check for incomplete packet (length smaller than expected) */
306 if (!pskb_may_pull(skb, headersize + payload_len))
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)))
319 skb_pull(skb, headersize);
321 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
322 /* chop off address/control */
328 if ((*skb->data) & 1) {
329 /* protocol is compressed */
330 *(u8 *)skb_push(skb, 1) = 0;
333 skb->ip_summed = CHECKSUM_NONE;
334 skb_set_network_header(skb, skb->head-skb->data);
335 ppp_input(&po->chan, skb);
337 return NET_RX_SUCCESS;
344 static int pptp_rcv(struct sk_buff *skb)
346 struct pppox_sock *po;
347 struct pptp_gre_header *header;
350 if (skb->pkt_type != PACKET_HOST)
353 if (!pskb_may_pull(skb, 12))
358 header = (struct pptp_gre_header *)skb->data;
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 */
368 po = lookup_chan(htons(header->call_id), iph->saddr);
372 return sk_receive_skb(sk_pppox(po), skb, 0);
379 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
382 struct sock *sk = sock->sk;
383 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
384 struct pppox_sock *po = pppox_sk(sk);
387 if (sockaddr_len < sizeof(struct sockaddr_pppox))
392 if (sk->sk_state & PPPOX_DEAD) {
397 if (sk->sk_state & PPPOX_BOUND) {
402 if (add_chan(po, &sp->sa_addr.pptp))
405 sk->sk_state |= PPPOX_BOUND;
412 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
413 int sockaddr_len, int flags)
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;
423 if (sockaddr_len < sizeof(struct sockaddr_pppox))
426 if (sp->sa_protocol != PX_PROTO_PPTP)
429 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
433 /* Check for already bound sockets */
434 if (sk->sk_state & PPPOX_CONNECTED) {
439 /* Check for already disconnected sockets, on attempts to disconnect */
440 if (sk->sk_state & PPPOX_DEAD) {
445 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
450 po->chan.private = sk;
451 po->chan.ops = &pptp_chan_ops;
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,
457 IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
459 error = -EHOSTUNREACH;
462 sk_setup_caps(sk, &rt->dst);
464 po->chan.mtu = dst_mtu(&rt->dst);
466 po->chan.mtu = PPP_MRU;
467 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
469 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
470 error = ppp_register_channel(&po->chan);
472 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
476 opt->dst_addr = sp->sa_addr.pptp;
477 sk->sk_state |= PPPOX_CONNECTED;
484 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
487 int len = sizeof(struct sockaddr_pppox);
488 struct sockaddr_pppox sp;
490 memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
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;
496 memcpy(uaddr, &sp, len);
501 static int pptp_release(struct socket *sock)
503 struct sock *sk = sock->sk;
504 struct pppox_sock *po;
512 if (sock_flag(sk, SOCK_DEAD)) {
521 pppox_unbind_sock(sk);
522 sk->sk_state = PPPOX_DEAD;
533 static void pptp_sock_destruct(struct sock *sk)
535 if (!(sk->sk_state & PPPOX_DEAD)) {
536 del_chan(pppox_sk(sk));
537 pppox_unbind_sock(sk);
539 skb_queue_purge(&sk->sk_receive_queue);
542 static int pptp_create(struct net *net, struct socket *sock, int kern)
546 struct pppox_sock *po;
547 struct pptp_opt *opt;
549 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
553 sock_init_data(sock, sk);
555 sock->state = SS_UNCONNECTED;
556 sock->ops = &pptp_ops;
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;
566 opt = &po->proto.pptp;
568 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
569 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
576 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
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;
589 val = opt->ppp_flags;
590 if (put_user(val, p))
595 if (get_user(val, p))
597 opt->ppp_flags = val & ~SC_RCV_BITS;
607 static const struct ppp_channel_ops pptp_chan_ops = {
608 .start_xmit = pptp_xmit,
609 .ioctl = pptp_ppp_ioctl,
612 static struct proto pptp_sk_proto __read_mostly = {
614 .owner = THIS_MODULE,
615 .obj_size = sizeof(struct pppox_sock),
618 static const struct proto_ops pptp_ops = {
620 .owner = THIS_MODULE,
621 .release = pptp_release,
623 .connect = pptp_connect,
624 .socketpair = sock_no_socketpair,
625 .accept = sock_no_accept,
626 .getname = pptp_getname,
627 .listen = sock_no_listen,
628 .shutdown = sock_no_shutdown,
629 .setsockopt = sock_no_setsockopt,
630 .getsockopt = sock_no_getsockopt,
631 .sendmsg = sock_no_sendmsg,
632 .recvmsg = sock_no_recvmsg,
633 .mmap = sock_no_mmap,
634 .ioctl = pppox_ioctl,
637 static const struct pppox_proto pppox_pptp_proto = {
638 .create = pptp_create,
639 .owner = THIS_MODULE,
642 static const struct gre_protocol gre_pptp_protocol = {
646 static int __init pptp_init_module(void)
649 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
651 callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
655 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
657 pr_err("PPTP: can't add gre protocol\n");
661 err = proto_register(&pptp_sk_proto, 0);
663 pr_err("PPTP: can't register sk_proto\n");
664 goto out_gre_del_protocol;
667 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
669 pr_err("PPTP: can't register pppox_proto\n");
670 goto out_unregister_sk_proto;
675 out_unregister_sk_proto:
676 proto_unregister(&pptp_sk_proto);
677 out_gre_del_protocol:
678 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
685 static void __exit pptp_exit_module(void)
687 unregister_pppox_proto(PX_PROTO_PPTP);
688 proto_unregister(&pptp_sk_proto);
689 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
693 module_init(pptp_init_module);
694 module_exit(pptp_exit_module);
696 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
697 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
698 MODULE_LICENSE("GPL");
699 MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);