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>
41 #include <linux/uaccess.h>
43 #define PPTP_DRIVER_VERSION "0.8.5"
45 #define MAX_CALLID 65535
47 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
48 static struct pppox_sock __rcu **callid_sock;
50 static DEFINE_SPINLOCK(chan_lock);
52 static struct proto pptp_sk_proto __read_mostly;
53 static const struct ppp_channel_ops pptp_chan_ops;
54 static const struct proto_ops pptp_ops;
56 #define PPP_LCP_ECHOREQ 0x09
57 #define PPP_LCP_ECHOREP 0x0A
58 #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
60 #define MISSING_WINDOW 20
61 #define WRAPPED(curseq, lastseq)\
62 ((((curseq) & 0xffffff00) == 0) &&\
63 (((lastseq) & 0xffffff00) == 0xffffff00))
65 #define PPTP_GRE_PROTO 0x880B
66 #define PPTP_GRE_VER 0x1
68 #define PPTP_GRE_FLAG_C 0x80
69 #define PPTP_GRE_FLAG_R 0x40
70 #define PPTP_GRE_FLAG_K 0x20
71 #define PPTP_GRE_FLAG_S 0x10
72 #define PPTP_GRE_FLAG_A 0x80
74 #define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
75 #define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
76 #define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
77 #define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
78 #define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)
80 #define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
81 struct pptp_gre_header {
91 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
93 struct pppox_sock *sock;
97 sock = rcu_dereference(callid_sock[call_id]);
99 opt = &sock->proto.pptp;
100 if (opt->dst_addr.sin_addr.s_addr != s_addr)
103 sock_hold(sk_pppox(sock));
110 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
112 struct pppox_sock *sock;
113 struct pptp_opt *opt;
118 for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
119 sock = rcu_dereference(callid_sock[i]);
122 opt = &sock->proto.pptp;
123 if (opt->dst_addr.call_id == call_id &&
124 opt->dst_addr.sin_addr.s_addr == d_addr)
129 return i < MAX_CALLID;
132 static int add_chan(struct pppox_sock *sock)
136 spin_lock(&chan_lock);
137 if (!sock->proto.pptp.src_addr.call_id) {
138 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
139 if (call_id == MAX_CALLID) {
140 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
141 if (call_id == MAX_CALLID)
144 sock->proto.pptp.src_addr.call_id = call_id;
145 } else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap))
148 set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
149 rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], sock);
150 spin_unlock(&chan_lock);
155 spin_unlock(&chan_lock);
159 static void del_chan(struct pppox_sock *sock)
161 spin_lock(&chan_lock);
162 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
163 RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
164 spin_unlock(&chan_lock);
168 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
170 struct sock *sk = (struct sock *) chan->private;
171 struct pppox_sock *po = pppox_sk(sk);
172 struct net *net = sock_net(sk);
173 struct pptp_opt *opt = &po->proto.pptp;
174 struct pptp_gre_header *hdr;
175 unsigned int header_len = sizeof(*hdr);
184 struct net_device *tdev;
188 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
191 rt = ip_route_output_ports(net, &fl4, NULL,
192 opt->dst_addr.sin_addr.s_addr,
193 opt->src_addr.sin_addr.s_addr,
201 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
203 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
204 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
210 skb_set_owner_w(new_skb, skb->sk);
216 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
218 /* compress protocol field */
219 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
222 /* Put in the address/control bytes if necessary */
223 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
224 data = skb_push(skb, 2);
225 data[0] = PPP_ALLSTATIONS;
231 seq_recv = opt->seq_recv;
233 if (opt->ack_sent == seq_recv)
234 header_len -= sizeof(hdr->ack);
236 /* Push down and install GRE header */
237 skb_push(skb, header_len);
238 hdr = (struct pptp_gre_header *)(skb->data);
240 hdr->flags = PPTP_GRE_FLAG_K;
241 hdr->ver = PPTP_GRE_VER;
242 hdr->protocol = htons(PPTP_GRE_PROTO);
243 hdr->call_id = htons(opt->dst_addr.call_id);
245 hdr->flags |= PPTP_GRE_FLAG_S;
246 hdr->seq = htonl(++opt->seq_sent);
247 if (opt->ack_sent != seq_recv) {
248 /* send ack with this message */
249 hdr->ver |= PPTP_GRE_FLAG_A;
250 hdr->ack = htonl(seq_recv);
251 opt->ack_sent = seq_recv;
253 hdr->payload_len = htons(len);
255 /* Push down and install the IP header. */
257 skb_reset_transport_header(skb);
258 skb_push(skb, sizeof(*iph));
259 skb_reset_network_header(skb);
260 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
261 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
265 iph->ihl = sizeof(struct iphdr) >> 2;
266 if (ip_dont_fragment(sk, &rt->dst))
267 iph->frag_off = htons(IP_DF);
270 iph->protocol = IPPROTO_GRE;
272 iph->daddr = fl4.daddr;
273 iph->saddr = fl4.saddr;
274 iph->ttl = ip4_dst_hoplimit(&rt->dst);
275 iph->tot_len = htons(skb->len);
278 skb_dst_set(skb, &rt->dst);
282 skb->ip_summed = CHECKSUM_NONE;
283 ip_select_ident(net, skb, NULL);
286 ip_local_out(net, skb->sk, skb);
294 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
296 struct pppox_sock *po = pppox_sk(sk);
297 struct pptp_opt *opt = &po->proto.pptp;
298 int headersize, payload_len, seq;
300 struct pptp_gre_header *header;
302 if (!(sk->sk_state & PPPOX_CONNECTED)) {
303 if (sock_queue_rcv_skb(sk, skb))
305 return NET_RX_SUCCESS;
308 header = (struct pptp_gre_header *)(skb->data);
309 headersize = sizeof(*header);
311 /* test if acknowledgement present */
312 if (PPTP_GRE_IS_A(header->ver)) {
315 if (!pskb_may_pull(skb, headersize))
317 header = (struct pptp_gre_header *)(skb->data);
319 /* ack in different place if S = 0 */
320 ack = PPTP_GRE_IS_S(header->flags) ? header->ack : header->seq;
324 if (ack > opt->ack_recv)
326 /* also handle sequence number wrap-around */
327 if (WRAPPED(ack, opt->ack_recv))
330 headersize -= sizeof(header->ack);
332 /* test if payload present */
333 if (!PPTP_GRE_IS_S(header->flags))
336 payload_len = ntohs(header->payload_len);
337 seq = ntohl(header->seq);
339 /* check for incomplete packet (length smaller than expected) */
340 if (!pskb_may_pull(skb, headersize + payload_len))
343 payload = skb->data + headersize;
344 /* check for expected sequence number */
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)))
353 skb_pull(skb, headersize);
355 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
356 /* chop off address/control */
362 if ((*skb->data) & 1) {
363 /* protocol is compressed */
364 skb_push(skb, 1)[0] = 0;
367 skb->ip_summed = CHECKSUM_NONE;
368 skb_set_network_header(skb, skb->head-skb->data);
369 ppp_input(&po->chan, skb);
371 return NET_RX_SUCCESS;
378 static int pptp_rcv(struct sk_buff *skb)
380 struct pppox_sock *po;
381 struct pptp_gre_header *header;
384 if (skb->pkt_type != PACKET_HOST)
387 if (!pskb_may_pull(skb, 12))
392 header = (struct pptp_gre_header *)skb->data;
394 if (ntohs(header->protocol) != PPTP_GRE_PROTO || /* PPTP-GRE protocol for PPTP */
395 PPTP_GRE_IS_C(header->flags) || /* flag C should be clear */
396 PPTP_GRE_IS_R(header->flags) || /* flag R should be clear */
397 !PPTP_GRE_IS_K(header->flags) || /* flag K should be set */
398 (header->flags&0xF) != 0) /* routing and recursion ctrl = 0 */
399 /* if invalid, discard this packet */
402 po = lookup_chan(htons(header->call_id), iph->saddr);
406 return sk_receive_skb(sk_pppox(po), skb, 0);
413 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
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;
424 opt->src_addr = sp->sa_addr.pptp;
432 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
433 int sockaddr_len, int flags)
435 struct sock *sk = sock->sk;
436 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
437 struct pppox_sock *po = pppox_sk(sk);
438 struct pptp_opt *opt = &po->proto.pptp;
443 if (sp->sa_protocol != PX_PROTO_PPTP)
446 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
450 /* Check for already bound sockets */
451 if (sk->sk_state & PPPOX_CONNECTED) {
456 /* Check for already disconnected sockets, on attempts to disconnect */
457 if (sk->sk_state & PPPOX_DEAD) {
462 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
467 po->chan.private = sk;
468 po->chan.ops = &pptp_chan_ops;
470 rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
471 opt->dst_addr.sin_addr.s_addr,
472 opt->src_addr.sin_addr.s_addr,
474 IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
476 error = -EHOSTUNREACH;
479 sk_setup_caps(sk, &rt->dst);
481 po->chan.mtu = dst_mtu(&rt->dst);
483 po->chan.mtu = PPP_MRU;
485 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
487 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
488 error = ppp_register_channel(&po->chan);
490 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
494 opt->dst_addr = sp->sa_addr.pptp;
495 sk->sk_state = PPPOX_CONNECTED;
502 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
503 int *usockaddr_len, int peer)
505 int len = sizeof(struct sockaddr_pppox);
506 struct sockaddr_pppox sp;
508 memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
510 sp.sa_family = AF_PPPOX;
511 sp.sa_protocol = PX_PROTO_PPTP;
512 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
514 memcpy(uaddr, &sp, len);
516 *usockaddr_len = len;
521 static int pptp_release(struct socket *sock)
523 struct sock *sk = sock->sk;
524 struct pppox_sock *po;
525 struct pptp_opt *opt;
533 if (sock_flag(sk, SOCK_DEAD)) {
539 opt = &po->proto.pptp;
542 pppox_unbind_sock(sk);
543 sk->sk_state = PPPOX_DEAD;
554 static void pptp_sock_destruct(struct sock *sk)
556 if (!(sk->sk_state & PPPOX_DEAD)) {
557 del_chan(pppox_sk(sk));
558 pppox_unbind_sock(sk);
560 skb_queue_purge(&sk->sk_receive_queue);
563 static int pptp_create(struct net *net, struct socket *sock, int kern)
567 struct pppox_sock *po;
568 struct pptp_opt *opt;
570 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
574 sock_init_data(sock, sk);
576 sock->state = SS_UNCONNECTED;
577 sock->ops = &pptp_ops;
579 sk->sk_backlog_rcv = pptp_rcv_core;
580 sk->sk_state = PPPOX_NONE;
581 sk->sk_type = SOCK_STREAM;
582 sk->sk_family = PF_PPPOX;
583 sk->sk_protocol = PX_PROTO_PPTP;
584 sk->sk_destruct = pptp_sock_destruct;
587 opt = &po->proto.pptp;
589 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
590 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
597 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
600 struct sock *sk = (struct sock *) chan->private;
601 struct pppox_sock *po = pppox_sk(sk);
602 struct pptp_opt *opt = &po->proto.pptp;
603 void __user *argp = (void __user *)arg;
604 int __user *p = argp;
610 val = opt->ppp_flags;
611 if (put_user(val, p))
616 if (get_user(val, p))
618 opt->ppp_flags = val & ~SC_RCV_BITS;
628 static const struct ppp_channel_ops pptp_chan_ops = {
629 .start_xmit = pptp_xmit,
630 .ioctl = pptp_ppp_ioctl,
633 static struct proto pptp_sk_proto __read_mostly = {
635 .owner = THIS_MODULE,
636 .obj_size = sizeof(struct pppox_sock),
639 static const struct proto_ops pptp_ops = {
641 .owner = THIS_MODULE,
642 .release = pptp_release,
644 .connect = pptp_connect,
645 .socketpair = sock_no_socketpair,
646 .accept = sock_no_accept,
647 .getname = pptp_getname,
648 .poll = sock_no_poll,
649 .listen = sock_no_listen,
650 .shutdown = sock_no_shutdown,
651 .setsockopt = sock_no_setsockopt,
652 .getsockopt = sock_no_getsockopt,
653 .sendmsg = sock_no_sendmsg,
654 .recvmsg = sock_no_recvmsg,
655 .mmap = sock_no_mmap,
656 .ioctl = pppox_ioctl,
659 static const struct pppox_proto pppox_pptp_proto = {
660 .create = pptp_create,
661 .owner = THIS_MODULE,
664 static const struct gre_protocol gre_pptp_protocol = {
668 static int __init pptp_init_module(void)
671 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
673 callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
677 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
679 pr_err("PPTP: can't add gre protocol\n");
683 err = proto_register(&pptp_sk_proto, 0);
685 pr_err("PPTP: can't register sk_proto\n");
686 goto out_gre_del_protocol;
689 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
691 pr_err("PPTP: can't register pppox_proto\n");
692 goto out_unregister_sk_proto;
697 out_unregister_sk_proto:
698 proto_unregister(&pptp_sk_proto);
699 out_gre_del_protocol:
700 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
707 static void __exit pptp_exit_module(void)
709 unregister_pppox_proto(PX_PROTO_PPTP);
710 proto_unregister(&pptp_sk_proto);
711 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
715 module_init(pptp_init_module);
716 module_exit(pptp_exit_module);
718 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
719 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
720 MODULE_LICENSE("GPL");