1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Point-to-Point Tunneling Protocol for Linux
5 * Authors: Dmitry Kozlov <xeb@mail.ru>
8 #include <linux/string.h>
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/errno.h>
13 #include <linux/netdevice.h>
14 #include <linux/net.h>
15 #include <linux/skbuff.h>
16 #include <linux/vmalloc.h>
17 #include <linux/init.h>
18 #include <linux/ppp_channel.h>
19 #include <linux/ppp_defs.h>
20 #include <linux/if_pppox.h>
21 #include <linux/ppp-ioctl.h>
22 #include <linux/notifier.h>
23 #include <linux/file.h>
26 #include <linux/rcupdate.h>
27 #include <linux/spinlock.h>
30 #include <net/protocol.h>
33 #include <net/route.h>
37 #include <linux/uaccess.h>
39 #define PPTP_DRIVER_VERSION "0.8.5"
41 #define MAX_CALLID 65535
43 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
44 static struct pppox_sock __rcu **callid_sock;
46 static DEFINE_SPINLOCK(chan_lock);
48 static struct proto pptp_sk_proto __read_mostly;
49 static const struct ppp_channel_ops pptp_chan_ops;
50 static const struct proto_ops pptp_ops;
52 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
54 struct pppox_sock *sock;
58 sock = rcu_dereference(callid_sock[call_id]);
60 opt = &sock->proto.pptp;
61 if (opt->dst_addr.sin_addr.s_addr != s_addr)
64 sock_hold(sk_pppox(sock));
71 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
73 struct pppox_sock *sock;
79 for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
80 sock = rcu_dereference(callid_sock[i]);
83 opt = &sock->proto.pptp;
84 if (opt->dst_addr.call_id == call_id &&
85 opt->dst_addr.sin_addr.s_addr == d_addr)
90 return i < MAX_CALLID;
93 static int add_chan(struct pppox_sock *sock,
98 spin_lock(&chan_lock);
100 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
101 if (call_id == MAX_CALLID) {
102 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
103 if (call_id == MAX_CALLID)
106 sa->call_id = call_id;
107 } else if (test_bit(sa->call_id, callid_bitmap)) {
111 sock->proto.pptp.src_addr = *sa;
112 set_bit(sa->call_id, callid_bitmap);
113 rcu_assign_pointer(callid_sock[sa->call_id], sock);
114 spin_unlock(&chan_lock);
119 spin_unlock(&chan_lock);
123 static void del_chan(struct pppox_sock *sock)
125 spin_lock(&chan_lock);
126 clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
127 RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
128 spin_unlock(&chan_lock);
131 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
133 struct sock *sk = (struct sock *) chan->private;
134 struct pppox_sock *po = pppox_sk(sk);
135 struct net *net = sock_net(sk);
136 struct pptp_opt *opt = &po->proto.pptp;
137 struct pptp_gre_header *hdr;
138 unsigned int header_len = sizeof(*hdr);
147 struct net_device *tdev;
151 if (sk_pppox(po)->sk_state & PPPOX_DEAD)
154 rt = ip_route_output_ports(net, &fl4, NULL,
155 opt->dst_addr.sin_addr.s_addr,
156 opt->src_addr.sin_addr.s_addr,
164 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
166 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
167 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
173 skb_set_owner_w(new_skb, skb->sk);
179 islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
181 /* compress protocol field */
182 if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
185 /* Put in the address/control bytes if necessary */
186 if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
187 data = skb_push(skb, 2);
188 data[0] = PPP_ALLSTATIONS;
194 seq_recv = opt->seq_recv;
196 if (opt->ack_sent == seq_recv)
197 header_len -= sizeof(hdr->ack);
199 /* Push down and install GRE header */
200 skb_push(skb, header_len);
201 hdr = (struct pptp_gre_header *)(skb->data);
203 hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
204 hdr->gre_hd.protocol = GRE_PROTO_PPP;
205 hdr->call_id = htons(opt->dst_addr.call_id);
207 hdr->seq = htonl(++opt->seq_sent);
208 if (opt->ack_sent != seq_recv) {
209 /* send ack with this message */
210 hdr->gre_hd.flags |= GRE_ACK;
211 hdr->ack = htonl(seq_recv);
212 opt->ack_sent = seq_recv;
214 hdr->payload_len = htons(len);
216 /* Push down and install the IP header. */
218 skb_reset_transport_header(skb);
219 skb_push(skb, sizeof(*iph));
220 skb_reset_network_header(skb);
221 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
222 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
226 iph->ihl = sizeof(struct iphdr) >> 2;
227 if (ip_dont_fragment(sk, &rt->dst))
228 iph->frag_off = htons(IP_DF);
231 iph->protocol = IPPROTO_GRE;
233 iph->daddr = fl4.daddr;
234 iph->saddr = fl4.saddr;
235 iph->ttl = ip4_dst_hoplimit(&rt->dst);
236 iph->tot_len = htons(skb->len);
239 skb_dst_set(skb, &rt->dst);
243 skb->ip_summed = CHECKSUM_NONE;
244 ip_select_ident(net, skb, NULL);
247 ip_local_out(net, skb->sk, skb);
255 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
257 struct pppox_sock *po = pppox_sk(sk);
258 struct pptp_opt *opt = &po->proto.pptp;
259 int headersize, payload_len, seq;
261 struct pptp_gre_header *header;
263 if (!(sk->sk_state & PPPOX_CONNECTED)) {
264 if (sock_queue_rcv_skb(sk, skb))
266 return NET_RX_SUCCESS;
269 header = (struct pptp_gre_header *)(skb->data);
270 headersize = sizeof(*header);
272 /* test if acknowledgement present */
273 if (GRE_IS_ACK(header->gre_hd.flags)) {
276 if (!pskb_may_pull(skb, headersize))
278 header = (struct pptp_gre_header *)(skb->data);
280 /* ack in different place if S = 0 */
281 ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
285 if (ack > opt->ack_recv)
287 /* also handle sequence number wrap-around */
288 if (WRAPPED(ack, opt->ack_recv))
291 headersize -= sizeof(header->ack);
293 /* test if payload present */
294 if (!GRE_IS_SEQ(header->gre_hd.flags))
297 payload_len = ntohs(header->payload_len);
298 seq = ntohl(header->seq);
300 /* check for incomplete packet (length smaller than expected) */
301 if (!pskb_may_pull(skb, headersize + payload_len))
304 payload = skb->data + headersize;
305 /* check for expected sequence number */
306 if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
307 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
308 (PPP_PROTOCOL(payload) == PPP_LCP) &&
309 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
314 skb_pull(skb, headersize);
316 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
317 /* chop off address/control */
323 skb->ip_summed = CHECKSUM_NONE;
324 skb_set_network_header(skb, skb->head-skb->data);
325 ppp_input(&po->chan, skb);
327 return NET_RX_SUCCESS;
334 static int pptp_rcv(struct sk_buff *skb)
336 struct pppox_sock *po;
337 struct pptp_gre_header *header;
340 if (skb->pkt_type != PACKET_HOST)
343 if (!pskb_may_pull(skb, 12))
348 header = (struct pptp_gre_header *)skb->data;
350 if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
351 GRE_IS_CSUM(header->gre_hd.flags) || /* flag CSUM should be clear */
352 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
353 !GRE_IS_KEY(header->gre_hd.flags) || /* flag KEY should be set */
354 (header->gre_hd.flags & GRE_FLAGS)) /* flag Recursion Ctrl should be clear */
355 /* if invalid, discard this packet */
358 po = lookup_chan(htons(header->call_id), iph->saddr);
362 return sk_receive_skb(sk_pppox(po), skb, 0);
369 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
372 struct sock *sk = sock->sk;
373 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
374 struct pppox_sock *po = pppox_sk(sk);
377 if (sockaddr_len < sizeof(struct sockaddr_pppox))
382 if (sk->sk_state & PPPOX_DEAD) {
387 if (sk->sk_state & PPPOX_BOUND) {
392 if (add_chan(po, &sp->sa_addr.pptp))
395 sk->sk_state |= PPPOX_BOUND;
402 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
403 int sockaddr_len, int flags)
405 struct sock *sk = sock->sk;
406 struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
407 struct pppox_sock *po = pppox_sk(sk);
408 struct pptp_opt *opt = &po->proto.pptp;
413 if (sockaddr_len < sizeof(struct sockaddr_pppox))
416 if (sp->sa_protocol != PX_PROTO_PPTP)
419 if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
423 /* Check for already bound sockets */
424 if (sk->sk_state & PPPOX_CONNECTED) {
429 /* Check for already disconnected sockets, on attempts to disconnect */
430 if (sk->sk_state & PPPOX_DEAD) {
435 if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
440 po->chan.private = sk;
441 po->chan.ops = &pptp_chan_ops;
443 rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
444 opt->dst_addr.sin_addr.s_addr,
445 opt->src_addr.sin_addr.s_addr,
447 IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
449 error = -EHOSTUNREACH;
452 sk_setup_caps(sk, &rt->dst);
454 po->chan.mtu = dst_mtu(&rt->dst);
456 po->chan.mtu = PPP_MRU;
457 po->chan.mtu -= PPTP_HEADER_OVERHEAD;
459 po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
460 error = ppp_register_channel(&po->chan);
462 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
466 opt->dst_addr = sp->sa_addr.pptp;
467 sk->sk_state |= PPPOX_CONNECTED;
474 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
477 int len = sizeof(struct sockaddr_pppox);
478 struct sockaddr_pppox sp;
480 memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
482 sp.sa_family = AF_PPPOX;
483 sp.sa_protocol = PX_PROTO_PPTP;
484 sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
486 memcpy(uaddr, &sp, len);
491 static int pptp_release(struct socket *sock)
493 struct sock *sk = sock->sk;
494 struct pppox_sock *po;
502 if (sock_flag(sk, SOCK_DEAD)) {
511 pppox_unbind_sock(sk);
512 sk->sk_state = PPPOX_DEAD;
523 static void pptp_sock_destruct(struct sock *sk)
525 if (!(sk->sk_state & PPPOX_DEAD)) {
526 del_chan(pppox_sk(sk));
527 pppox_unbind_sock(sk);
529 skb_queue_purge(&sk->sk_receive_queue);
530 dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
533 static int pptp_create(struct net *net, struct socket *sock, int kern)
537 struct pppox_sock *po;
538 struct pptp_opt *opt;
540 sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
544 sock_init_data(sock, sk);
546 sock->state = SS_UNCONNECTED;
547 sock->ops = &pptp_ops;
549 sk->sk_backlog_rcv = pptp_rcv_core;
550 sk->sk_state = PPPOX_NONE;
551 sk->sk_type = SOCK_STREAM;
552 sk->sk_family = PF_PPPOX;
553 sk->sk_protocol = PX_PROTO_PPTP;
554 sk->sk_destruct = pptp_sock_destruct;
557 opt = &po->proto.pptp;
559 opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
560 opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
567 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
570 struct sock *sk = (struct sock *) chan->private;
571 struct pppox_sock *po = pppox_sk(sk);
572 struct pptp_opt *opt = &po->proto.pptp;
573 void __user *argp = (void __user *)arg;
574 int __user *p = argp;
580 val = opt->ppp_flags;
581 if (put_user(val, p))
586 if (get_user(val, p))
588 opt->ppp_flags = val & ~SC_RCV_BITS;
598 static const struct ppp_channel_ops pptp_chan_ops = {
599 .start_xmit = pptp_xmit,
600 .ioctl = pptp_ppp_ioctl,
603 static struct proto pptp_sk_proto __read_mostly = {
605 .owner = THIS_MODULE,
606 .obj_size = sizeof(struct pppox_sock),
609 static const struct proto_ops pptp_ops = {
611 .owner = THIS_MODULE,
612 .release = pptp_release,
614 .connect = pptp_connect,
615 .socketpair = sock_no_socketpair,
616 .accept = sock_no_accept,
617 .getname = pptp_getname,
618 .listen = sock_no_listen,
619 .shutdown = sock_no_shutdown,
620 .setsockopt = sock_no_setsockopt,
621 .getsockopt = sock_no_getsockopt,
622 .sendmsg = sock_no_sendmsg,
623 .recvmsg = sock_no_recvmsg,
624 .mmap = sock_no_mmap,
625 .ioctl = pppox_ioctl,
627 .compat_ioctl = pppox_compat_ioctl,
631 static const struct pppox_proto pppox_pptp_proto = {
632 .create = pptp_create,
633 .owner = THIS_MODULE,
636 static const struct gre_protocol gre_pptp_protocol = {
640 static int __init pptp_init_module(void)
643 pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
645 callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
649 err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
651 pr_err("PPTP: can't add gre protocol\n");
655 err = proto_register(&pptp_sk_proto, 0);
657 pr_err("PPTP: can't register sk_proto\n");
658 goto out_gre_del_protocol;
661 err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
663 pr_err("PPTP: can't register pppox_proto\n");
664 goto out_unregister_sk_proto;
669 out_unregister_sk_proto:
670 proto_unregister(&pptp_sk_proto);
671 out_gre_del_protocol:
672 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
679 static void __exit pptp_exit_module(void)
681 unregister_pppox_proto(PX_PROTO_PPTP);
682 proto_unregister(&pptp_sk_proto);
683 gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
687 module_init(pptp_init_module);
688 module_exit(pptp_exit_module);
690 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
691 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
692 MODULE_LICENSE("GPL");
693 MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);