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/version.h>
34 #include <linux/rcupdate.h>
35 #include <linux/spinlock.h>
38 #include <net/protocol.h>
41 #include <net/route.h>
44 #include <linux/uaccess.h>
46 #define PPTP_DRIVER_VERSION "0.8.5"
48 #define MAX_CALLID 65535
50 static DECLARE_BITMAP(callid_bitmap
, MAX_CALLID
+ 1);
51 static struct pppox_sock
**callid_sock
;
53 static DEFINE_SPINLOCK(chan_lock
);
55 static struct proto pptp_sk_proto __read_mostly
;
56 static const struct ppp_channel_ops pptp_chan_ops
;
57 static const struct proto_ops pptp_ops
;
59 #define PPP_LCP_ECHOREQ 0x09
60 #define PPP_LCP_ECHOREP 0x0A
61 #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
63 #define MISSING_WINDOW 20
64 #define WRAPPED(curseq, lastseq)\
65 ((((curseq) & 0xffffff00) == 0) &&\
66 (((lastseq) & 0xffffff00) == 0xffffff00))
68 #define PPTP_GRE_PROTO 0x880B
69 #define PPTP_GRE_VER 0x1
71 #define PPTP_GRE_FLAG_C 0x80
72 #define PPTP_GRE_FLAG_R 0x40
73 #define PPTP_GRE_FLAG_K 0x20
74 #define PPTP_GRE_FLAG_S 0x10
75 #define PPTP_GRE_FLAG_A 0x80
77 #define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
78 #define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
79 #define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
80 #define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
81 #define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)
83 #define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
84 struct pptp_gre_header
{
94 static struct pppox_sock
*lookup_chan(u16 call_id
, __be32 s_addr
)
96 struct pppox_sock
*sock
;
100 sock
= rcu_dereference(callid_sock
[call_id
]);
102 opt
= &sock
->proto
.pptp
;
103 if (opt
->dst_addr
.sin_addr
.s_addr
!= s_addr
)
106 sock_hold(sk_pppox(sock
));
113 static int lookup_chan_dst(u16 call_id
, __be32 d_addr
)
115 struct pppox_sock
*sock
;
116 struct pptp_opt
*opt
;
120 for (i
= find_next_bit(callid_bitmap
, MAX_CALLID
, 1); i
< MAX_CALLID
;
121 i
= find_next_bit(callid_bitmap
, MAX_CALLID
, i
+ 1)) {
122 sock
= rcu_dereference(callid_sock
[i
]);
125 opt
= &sock
->proto
.pptp
;
126 if (opt
->dst_addr
.call_id
== call_id
&&
127 opt
->dst_addr
.sin_addr
.s_addr
== d_addr
)
132 return i
< MAX_CALLID
;
135 static int add_chan(struct pppox_sock
*sock
)
139 spin_lock(&chan_lock
);
140 if (!sock
->proto
.pptp
.src_addr
.call_id
) {
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 sock
->proto
.pptp
.src_addr
.call_id
= call_id
;
148 } else if (test_bit(sock
->proto
.pptp
.src_addr
.call_id
, callid_bitmap
))
151 set_bit(sock
->proto
.pptp
.src_addr
.call_id
, callid_bitmap
);
152 rcu_assign_pointer(callid_sock
[sock
->proto
.pptp
.src_addr
.call_id
], sock
);
153 spin_unlock(&chan_lock
);
158 spin_unlock(&chan_lock
);
162 static void del_chan(struct pppox_sock
*sock
)
164 spin_lock(&chan_lock
);
165 clear_bit(sock
->proto
.pptp
.src_addr
.call_id
, callid_bitmap
);
166 rcu_assign_pointer(callid_sock
[sock
->proto
.pptp
.src_addr
.call_id
], NULL
);
167 spin_unlock(&chan_lock
);
171 static int pptp_xmit(struct ppp_channel
*chan
, struct sk_buff
*skb
)
173 struct sock
*sk
= (struct sock
*) chan
->private;
174 struct pppox_sock
*po
= pppox_sk(sk
);
175 struct pptp_opt
*opt
= &po
->proto
.pptp
;
176 struct pptp_gre_header
*hdr
;
177 unsigned int header_len
= sizeof(*hdr
);
186 struct net_device
*tdev
;
190 if (sk_pppox(po
)->sk_state
& PPPOX_DEAD
)
194 struct flowi fl
= { .oif
= 0,
197 .daddr
= opt
->dst_addr
.sin_addr
.s_addr
,
198 .saddr
= opt
->src_addr
.sin_addr
.s_addr
,
199 .tos
= RT_TOS(0) } },
200 .proto
= IPPROTO_GRE
};
201 err
= ip_route_output_key(&init_net
, &rt
, &fl
);
207 max_headroom
= LL_RESERVED_SPACE(tdev
) + sizeof(*iph
) + sizeof(*hdr
) + 2;
209 if (skb_headroom(skb
) < max_headroom
|| skb_cloned(skb
) || skb_shared(skb
)) {
210 struct sk_buff
*new_skb
= skb_realloc_headroom(skb
, max_headroom
);
216 skb_set_owner_w(new_skb
, skb
->sk
);
222 islcp
= ((data
[0] << 8) + data
[1]) == PPP_LCP
&& 1 <= data
[2] && data
[2] <= 7;
224 /* compress protocol field */
225 if ((opt
->ppp_flags
& SC_COMP_PROT
) && data
[0] == 0 && !islcp
)
228 /* Put in the address/control bytes if necessary */
229 if ((opt
->ppp_flags
& SC_COMP_AC
) == 0 || islcp
) {
230 data
= skb_push(skb
, 2);
231 data
[0] = PPP_ALLSTATIONS
;
237 seq_recv
= opt
->seq_recv
;
239 if (opt
->ack_sent
== seq_recv
)
240 header_len
-= sizeof(hdr
->ack
);
242 /* Push down and install GRE header */
243 skb_push(skb
, header_len
);
244 hdr
= (struct pptp_gre_header
*)(skb
->data
);
246 hdr
->flags
= PPTP_GRE_FLAG_K
;
247 hdr
->ver
= PPTP_GRE_VER
;
248 hdr
->protocol
= htons(PPTP_GRE_PROTO
);
249 hdr
->call_id
= htons(opt
->dst_addr
.call_id
);
251 hdr
->flags
|= PPTP_GRE_FLAG_S
;
252 hdr
->seq
= htonl(++opt
->seq_sent
);
253 if (opt
->ack_sent
!= seq_recv
) {
254 /* send ack with this message */
255 hdr
->ver
|= PPTP_GRE_FLAG_A
;
256 hdr
->ack
= htonl(seq_recv
);
257 opt
->ack_sent
= seq_recv
;
259 hdr
->payload_len
= htons(len
);
261 /* Push down and install the IP header. */
263 skb_reset_transport_header(skb
);
264 skb_push(skb
, sizeof(*iph
));
265 skb_reset_network_header(skb
);
266 memset(&(IPCB(skb
)->opt
), 0, sizeof(IPCB(skb
)->opt
));
267 IPCB(skb
)->flags
&= ~(IPSKB_XFRM_TUNNEL_SIZE
| IPSKB_XFRM_TRANSFORMED
| IPSKB_REROUTED
);
271 iph
->ihl
= sizeof(struct iphdr
) >> 2;
272 if (ip_dont_fragment(sk
, &rt
->dst
))
273 iph
->frag_off
= htons(IP_DF
);
276 iph
->protocol
= IPPROTO_GRE
;
278 iph
->daddr
= rt
->rt_dst
;
279 iph
->saddr
= rt
->rt_src
;
280 iph
->ttl
= dst_metric(&rt
->dst
, RTAX_HOPLIMIT
);
281 iph
->tot_len
= htons(skb
->len
);
284 skb_dst_set(skb
, &rt
->dst
);
288 skb
->ip_summed
= CHECKSUM_NONE
;
289 ip_select_ident(iph
, &rt
->dst
, 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
);
314 /* test if acknowledgement present */
315 if (PPTP_GRE_IS_A(header
->ver
)) {
316 __u32 ack
= (PPTP_GRE_IS_S(header
->flags
)) ?
317 header
->ack
: header
->seq
; /* ack in different place if S = 0 */
321 if (ack
> opt
->ack_recv
)
323 /* also handle sequence number wrap-around */
324 if (WRAPPED(ack
, opt
->ack_recv
))
328 /* test if payload present */
329 if (!PPTP_GRE_IS_S(header
->flags
))
332 headersize
= sizeof(*header
);
333 payload_len
= ntohs(header
->payload_len
);
334 seq
= ntohl(header
->seq
);
336 /* no ack present? */
337 if (!PPTP_GRE_IS_A(header
->ver
))
338 headersize
-= sizeof(header
->ack
);
339 /* check for incomplete packet (length smaller than expected) */
340 if (skb
->len
- 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
;
434 static int pptp_connect(struct socket
*sock
, struct sockaddr
*uservaddr
,
435 int sockaddr_len
, int flags
)
437 struct sock
*sk
= sock
->sk
;
438 struct sockaddr_pppox
*sp
= (struct sockaddr_pppox
*) uservaddr
;
439 struct pppox_sock
*po
= pppox_sk(sk
);
440 struct pptp_opt
*opt
= &po
->proto
.pptp
;
444 if (sp
->sa_protocol
!= PX_PROTO_PPTP
)
447 if (lookup_chan_dst(sp
->sa_addr
.pptp
.call_id
, sp
->sa_addr
.pptp
.sin_addr
.s_addr
))
451 /* Check for already bound sockets */
452 if (sk
->sk_state
& PPPOX_CONNECTED
) {
457 /* Check for already disconnected sockets, on attempts to disconnect */
458 if (sk
->sk_state
& PPPOX_DEAD
) {
463 if (!opt
->src_addr
.sin_addr
.s_addr
|| !sp
->sa_addr
.pptp
.sin_addr
.s_addr
) {
468 po
->chan
.private = sk
;
469 po
->chan
.ops
= &pptp_chan_ops
;
475 .daddr
= opt
->dst_addr
.sin_addr
.s_addr
,
476 .saddr
= opt
->src_addr
.sin_addr
.s_addr
,
477 .tos
= RT_CONN_FLAGS(sk
) } },
478 .proto
= IPPROTO_GRE
};
479 security_sk_classify_flow(sk
, &fl
);
480 if (ip_route_output_key(&init_net
, &rt
, &fl
)) {
481 error
= -EHOSTUNREACH
;
484 sk_setup_caps(sk
, &rt
->dst
);
486 po
->chan
.mtu
= dst_mtu(&rt
->dst
);
488 po
->chan
.mtu
= PPP_MTU
;
490 po
->chan
.mtu
-= PPTP_HEADER_OVERHEAD
;
492 po
->chan
.hdrlen
= 2 + sizeof(struct pptp_gre_header
);
493 error
= ppp_register_channel(&po
->chan
);
495 pr_err("PPTP: failed to register PPP channel (%d)\n", error
);
499 opt
->dst_addr
= sp
->sa_addr
.pptp
;
500 sk
->sk_state
= PPPOX_CONNECTED
;
507 static int pptp_getname(struct socket
*sock
, struct sockaddr
*uaddr
,
508 int *usockaddr_len
, int peer
)
510 int len
= sizeof(struct sockaddr_pppox
);
511 struct sockaddr_pppox sp
;
513 sp
.sa_family
= AF_PPPOX
;
514 sp
.sa_protocol
= PX_PROTO_PPTP
;
515 sp
.sa_addr
.pptp
= pppox_sk(sock
->sk
)->proto
.pptp
.src_addr
;
517 memcpy(uaddr
, &sp
, len
);
519 *usockaddr_len
= len
;
524 static int pptp_release(struct socket
*sock
)
526 struct sock
*sk
= sock
->sk
;
527 struct pppox_sock
*po
;
528 struct pptp_opt
*opt
;
536 if (sock_flag(sk
, SOCK_DEAD
)) {
542 opt
= &po
->proto
.pptp
;
545 pppox_unbind_sock(sk
);
546 sk
->sk_state
= PPPOX_DEAD
;
557 static void pptp_sock_destruct(struct sock
*sk
)
559 if (!(sk
->sk_state
& PPPOX_DEAD
)) {
560 del_chan(pppox_sk(sk
));
561 pppox_unbind_sock(sk
);
563 skb_queue_purge(&sk
->sk_receive_queue
);
566 static int pptp_create(struct net
*net
, struct socket
*sock
)
570 struct pppox_sock
*po
;
571 struct pptp_opt
*opt
;
573 sk
= sk_alloc(net
, PF_PPPOX
, GFP_KERNEL
, &pptp_sk_proto
);
577 sock_init_data(sock
, sk
);
579 sock
->state
= SS_UNCONNECTED
;
580 sock
->ops
= &pptp_ops
;
582 sk
->sk_backlog_rcv
= pptp_rcv_core
;
583 sk
->sk_state
= PPPOX_NONE
;
584 sk
->sk_type
= SOCK_STREAM
;
585 sk
->sk_family
= PF_PPPOX
;
586 sk
->sk_protocol
= PX_PROTO_PPTP
;
587 sk
->sk_destruct
= pptp_sock_destruct
;
590 opt
= &po
->proto
.pptp
;
592 opt
->seq_sent
= 0; opt
->seq_recv
= 0;
593 opt
->ack_recv
= 0; opt
->ack_sent
= 0;
600 static int pptp_ppp_ioctl(struct ppp_channel
*chan
, unsigned int cmd
,
603 struct sock
*sk
= (struct sock
*) chan
->private;
604 struct pppox_sock
*po
= pppox_sk(sk
);
605 struct pptp_opt
*opt
= &po
->proto
.pptp
;
606 void __user
*argp
= (void __user
*)arg
;
607 int __user
*p
= argp
;
613 val
= opt
->ppp_flags
;
614 if (put_user(val
, p
))
619 if (get_user(val
, p
))
621 opt
->ppp_flags
= val
& ~SC_RCV_BITS
;
631 static const struct ppp_channel_ops pptp_chan_ops
= {
632 .start_xmit
= pptp_xmit
,
633 .ioctl
= pptp_ppp_ioctl
,
636 static struct proto pptp_sk_proto __read_mostly
= {
638 .owner
= THIS_MODULE
,
639 .obj_size
= sizeof(struct pppox_sock
),
642 static const struct proto_ops pptp_ops
= {
644 .owner
= THIS_MODULE
,
645 .release
= pptp_release
,
647 .connect
= pptp_connect
,
648 .socketpair
= sock_no_socketpair
,
649 .accept
= sock_no_accept
,
650 .getname
= pptp_getname
,
651 .poll
= sock_no_poll
,
652 .listen
= sock_no_listen
,
653 .shutdown
= sock_no_shutdown
,
654 .setsockopt
= sock_no_setsockopt
,
655 .getsockopt
= sock_no_getsockopt
,
656 .sendmsg
= sock_no_sendmsg
,
657 .recvmsg
= sock_no_recvmsg
,
658 .mmap
= sock_no_mmap
,
659 .ioctl
= pppox_ioctl
,
662 static const struct pppox_proto pppox_pptp_proto
= {
663 .create
= pptp_create
,
664 .owner
= THIS_MODULE
,
667 static const struct gre_protocol gre_pptp_protocol
= {
671 static int __init
pptp_init_module(void)
674 pr_info("PPTP driver version " PPTP_DRIVER_VERSION
"\n");
676 callid_sock
= __vmalloc((MAX_CALLID
+ 1) * sizeof(void *),
677 GFP_KERNEL
| __GFP_ZERO
, PAGE_KERNEL
);
679 pr_err("PPTP: cann't allocate memory\n");
683 err
= gre_add_protocol(&gre_pptp_protocol
, GREPROTO_PPTP
);
685 pr_err("PPTP: can't add gre protocol\n");
689 err
= proto_register(&pptp_sk_proto
, 0);
691 pr_err("PPTP: can't register sk_proto\n");
692 goto out_gre_del_protocol
;
695 err
= register_pppox_proto(PX_PROTO_PPTP
, &pppox_pptp_proto
);
697 pr_err("PPTP: can't register pppox_proto\n");
698 goto out_unregister_sk_proto
;
703 out_unregister_sk_proto
:
704 proto_unregister(&pptp_sk_proto
);
705 out_gre_del_protocol
:
706 gre_del_protocol(&gre_pptp_protocol
, GREPROTO_PPTP
);
713 static void __exit
pptp_exit_module(void)
715 unregister_pppox_proto(PX_PROTO_PPTP
);
716 proto_unregister(&pptp_sk_proto
);
717 gre_del_protocol(&gre_pptp_protocol
, GREPROTO_PPTP
);
721 module_init(pptp_init_module
);
722 module_exit(pptp_exit_module
);
724 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
725 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
726 MODULE_LICENSE("GPL");