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");