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/rcupdate.h>
34 #include <linux/spinlock.h>
37 #include <net/protocol.h>
40 #include <net/route.h>
43 #include <linux/uaccess.h>
45 #define PPTP_DRIVER_VERSION "0.8.5"
47 #define MAX_CALLID 65535
49 static DECLARE_BITMAP(callid_bitmap
, MAX_CALLID
+ 1);
50 static struct pppox_sock
**callid_sock
;
52 static DEFINE_SPINLOCK(chan_lock
);
54 static struct proto pptp_sk_proto __read_mostly
;
55 static const struct ppp_channel_ops pptp_chan_ops
;
56 static const struct proto_ops pptp_ops
;
58 #define PPP_LCP_ECHOREQ 0x09
59 #define PPP_LCP_ECHOREP 0x0A
60 #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
62 #define MISSING_WINDOW 20
63 #define WRAPPED(curseq, lastseq)\
64 ((((curseq) & 0xffffff00) == 0) &&\
65 (((lastseq) & 0xffffff00) == 0xffffff00))
67 #define PPTP_GRE_PROTO 0x880B
68 #define PPTP_GRE_VER 0x1
70 #define PPTP_GRE_FLAG_C 0x80
71 #define PPTP_GRE_FLAG_R 0x40
72 #define PPTP_GRE_FLAG_K 0x20
73 #define PPTP_GRE_FLAG_S 0x10
74 #define PPTP_GRE_FLAG_A 0x80
76 #define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
77 #define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
78 #define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
79 #define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
80 #define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)
82 #define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
83 struct pptp_gre_header
{
93 static struct pppox_sock
*lookup_chan(u16 call_id
, __be32 s_addr
)
95 struct pppox_sock
*sock
;
99 sock
= rcu_dereference(callid_sock
[call_id
]);
101 opt
= &sock
->proto
.pptp
;
102 if (opt
->dst_addr
.sin_addr
.s_addr
!= s_addr
)
105 sock_hold(sk_pppox(sock
));
112 static int lookup_chan_dst(u16 call_id
, __be32 d_addr
)
114 struct pppox_sock
*sock
;
115 struct pptp_opt
*opt
;
119 for (i
= find_next_bit(callid_bitmap
, MAX_CALLID
, 1); i
< MAX_CALLID
;
120 i
= find_next_bit(callid_bitmap
, MAX_CALLID
, i
+ 1)) {
121 sock
= rcu_dereference(callid_sock
[i
]);
124 opt
= &sock
->proto
.pptp
;
125 if (opt
->dst_addr
.call_id
== call_id
&&
126 opt
->dst_addr
.sin_addr
.s_addr
== d_addr
)
131 return i
< MAX_CALLID
;
134 static int add_chan(struct pppox_sock
*sock
)
138 spin_lock(&chan_lock
);
139 if (!sock
->proto
.pptp
.src_addr
.call_id
) {
140 call_id
= find_next_zero_bit(callid_bitmap
, MAX_CALLID
, call_id
+ 1);
141 if (call_id
== MAX_CALLID
) {
142 call_id
= find_next_zero_bit(callid_bitmap
, MAX_CALLID
, 1);
143 if (call_id
== MAX_CALLID
)
146 sock
->proto
.pptp
.src_addr
.call_id
= call_id
;
147 } else if (test_bit(sock
->proto
.pptp
.src_addr
.call_id
, callid_bitmap
))
150 set_bit(sock
->proto
.pptp
.src_addr
.call_id
, callid_bitmap
);
151 rcu_assign_pointer(callid_sock
[sock
->proto
.pptp
.src_addr
.call_id
], sock
);
152 spin_unlock(&chan_lock
);
157 spin_unlock(&chan_lock
);
161 static void del_chan(struct pppox_sock
*sock
)
163 spin_lock(&chan_lock
);
164 clear_bit(sock
->proto
.pptp
.src_addr
.call_id
, callid_bitmap
);
165 rcu_assign_pointer(callid_sock
[sock
->proto
.pptp
.src_addr
.call_id
], NULL
);
166 spin_unlock(&chan_lock
);
170 static int pptp_xmit(struct ppp_channel
*chan
, struct sk_buff
*skb
)
172 struct sock
*sk
= (struct sock
*) chan
->private;
173 struct pppox_sock
*po
= pppox_sk(sk
);
174 struct pptp_opt
*opt
= &po
->proto
.pptp
;
175 struct pptp_gre_header
*hdr
;
176 unsigned int header_len
= sizeof(*hdr
);
185 struct net_device
*tdev
;
189 if (sk_pppox(po
)->sk_state
& PPPOX_DEAD
)
192 rt
= ip_route_output_ports(&init_net
, &fl4
, NULL
,
193 opt
->dst_addr
.sin_addr
.s_addr
,
194 opt
->src_addr
.sin_addr
.s_addr
,
202 max_headroom
= LL_RESERVED_SPACE(tdev
) + sizeof(*iph
) + sizeof(*hdr
) + 2;
204 if (skb_headroom(skb
) < max_headroom
|| skb_cloned(skb
) || skb_shared(skb
)) {
205 struct sk_buff
*new_skb
= skb_realloc_headroom(skb
, max_headroom
);
211 skb_set_owner_w(new_skb
, skb
->sk
);
217 islcp
= ((data
[0] << 8) + data
[1]) == PPP_LCP
&& 1 <= data
[2] && data
[2] <= 7;
219 /* compress protocol field */
220 if ((opt
->ppp_flags
& SC_COMP_PROT
) && data
[0] == 0 && !islcp
)
223 /* Put in the address/control bytes if necessary */
224 if ((opt
->ppp_flags
& SC_COMP_AC
) == 0 || islcp
) {
225 data
= skb_push(skb
, 2);
226 data
[0] = PPP_ALLSTATIONS
;
232 seq_recv
= opt
->seq_recv
;
234 if (opt
->ack_sent
== seq_recv
)
235 header_len
-= sizeof(hdr
->ack
);
237 /* Push down and install GRE header */
238 skb_push(skb
, header_len
);
239 hdr
= (struct pptp_gre_header
*)(skb
->data
);
241 hdr
->flags
= PPTP_GRE_FLAG_K
;
242 hdr
->ver
= PPTP_GRE_VER
;
243 hdr
->protocol
= htons(PPTP_GRE_PROTO
);
244 hdr
->call_id
= htons(opt
->dst_addr
.call_id
);
246 hdr
->flags
|= PPTP_GRE_FLAG_S
;
247 hdr
->seq
= htonl(++opt
->seq_sent
);
248 if (opt
->ack_sent
!= seq_recv
) {
249 /* send ack with this message */
250 hdr
->ver
|= PPTP_GRE_FLAG_A
;
251 hdr
->ack
= htonl(seq_recv
);
252 opt
->ack_sent
= seq_recv
;
254 hdr
->payload_len
= htons(len
);
256 /* Push down and install the IP header. */
258 skb_reset_transport_header(skb
);
259 skb_push(skb
, sizeof(*iph
));
260 skb_reset_network_header(skb
);
261 memset(&(IPCB(skb
)->opt
), 0, sizeof(IPCB(skb
)->opt
));
262 IPCB(skb
)->flags
&= ~(IPSKB_XFRM_TUNNEL_SIZE
| IPSKB_XFRM_TRANSFORMED
| IPSKB_REROUTED
);
266 iph
->ihl
= sizeof(struct iphdr
) >> 2;
267 if (ip_dont_fragment(sk
, &rt
->dst
))
268 iph
->frag_off
= htons(IP_DF
);
271 iph
->protocol
= IPPROTO_GRE
;
273 iph
->daddr
= fl4
.daddr
;
274 iph
->saddr
= fl4
.saddr
;
275 iph
->ttl
= ip4_dst_hoplimit(&rt
->dst
);
276 iph
->tot_len
= htons(skb
->len
);
279 skb_dst_set(skb
, &rt
->dst
);
283 skb
->ip_summed
= CHECKSUM_NONE
;
284 ip_select_ident(iph
, &rt
->dst
, NULL
);
295 static int pptp_rcv_core(struct sock
*sk
, struct sk_buff
*skb
)
297 struct pppox_sock
*po
= pppox_sk(sk
);
298 struct pptp_opt
*opt
= &po
->proto
.pptp
;
299 int headersize
, payload_len
, seq
;
301 struct pptp_gre_header
*header
;
303 if (!(sk
->sk_state
& PPPOX_CONNECTED
)) {
304 if (sock_queue_rcv_skb(sk
, skb
))
306 return NET_RX_SUCCESS
;
309 header
= (struct pptp_gre_header
*)(skb
->data
);
311 /* test if acknowledgement present */
312 if (PPTP_GRE_IS_A(header
->ver
)) {
313 __u32 ack
= (PPTP_GRE_IS_S(header
->flags
)) ?
314 header
->ack
: header
->seq
; /* ack in different place if S = 0 */
318 if (ack
> opt
->ack_recv
)
320 /* also handle sequence number wrap-around */
321 if (WRAPPED(ack
, opt
->ack_recv
))
325 /* test if payload present */
326 if (!PPTP_GRE_IS_S(header
->flags
))
329 headersize
= sizeof(*header
);
330 payload_len
= ntohs(header
->payload_len
);
331 seq
= ntohl(header
->seq
);
333 /* no ack present? */
334 if (!PPTP_GRE_IS_A(header
->ver
))
335 headersize
-= sizeof(header
->ack
);
336 /* check for incomplete packet (length smaller than expected) */
337 if (skb
->len
- headersize
< payload_len
)
340 payload
= skb
->data
+ headersize
;
341 /* check for expected sequence number */
342 if (seq
< opt
->seq_recv
+ 1 || WRAPPED(opt
->seq_recv
, seq
)) {
343 if ((payload
[0] == PPP_ALLSTATIONS
) && (payload
[1] == PPP_UI
) &&
344 (PPP_PROTOCOL(payload
) == PPP_LCP
) &&
345 ((payload
[4] == PPP_LCP_ECHOREQ
) || (payload
[4] == PPP_LCP_ECHOREP
)))
350 skb_pull(skb
, headersize
);
352 if (payload
[0] == PPP_ALLSTATIONS
&& payload
[1] == PPP_UI
) {
353 /* chop off address/control */
359 if ((*skb
->data
) & 1) {
360 /* protocol is compressed */
361 skb_push(skb
, 1)[0] = 0;
364 skb
->ip_summed
= CHECKSUM_NONE
;
365 skb_set_network_header(skb
, skb
->head
-skb
->data
);
366 ppp_input(&po
->chan
, skb
);
368 return NET_RX_SUCCESS
;
375 static int pptp_rcv(struct sk_buff
*skb
)
377 struct pppox_sock
*po
;
378 struct pptp_gre_header
*header
;
381 if (skb
->pkt_type
!= PACKET_HOST
)
384 if (!pskb_may_pull(skb
, 12))
389 header
= (struct pptp_gre_header
*)skb
->data
;
391 if (ntohs(header
->protocol
) != PPTP_GRE_PROTO
|| /* PPTP-GRE protocol for PPTP */
392 PPTP_GRE_IS_C(header
->flags
) || /* flag C should be clear */
393 PPTP_GRE_IS_R(header
->flags
) || /* flag R should be clear */
394 !PPTP_GRE_IS_K(header
->flags
) || /* flag K should be set */
395 (header
->flags
&0xF) != 0) /* routing and recursion ctrl = 0 */
396 /* if invalid, discard this packet */
399 po
= lookup_chan(htons(header
->call_id
), iph
->saddr
);
403 return sk_receive_skb(sk_pppox(po
), skb
, 0);
410 static int pptp_bind(struct socket
*sock
, struct sockaddr
*uservaddr
,
413 struct sock
*sk
= sock
->sk
;
414 struct sockaddr_pppox
*sp
= (struct sockaddr_pppox
*) uservaddr
;
415 struct pppox_sock
*po
= pppox_sk(sk
);
416 struct pptp_opt
*opt
= &po
->proto
.pptp
;
421 opt
->src_addr
= sp
->sa_addr
.pptp
;
431 static int pptp_connect(struct socket
*sock
, struct sockaddr
*uservaddr
,
432 int sockaddr_len
, int flags
)
434 struct sock
*sk
= sock
->sk
;
435 struct sockaddr_pppox
*sp
= (struct sockaddr_pppox
*) uservaddr
;
436 struct pppox_sock
*po
= pppox_sk(sk
);
437 struct pptp_opt
*opt
= &po
->proto
.pptp
;
442 if (sp
->sa_protocol
!= PX_PROTO_PPTP
)
445 if (lookup_chan_dst(sp
->sa_addr
.pptp
.call_id
, sp
->sa_addr
.pptp
.sin_addr
.s_addr
))
449 /* Check for already bound sockets */
450 if (sk
->sk_state
& PPPOX_CONNECTED
) {
455 /* Check for already disconnected sockets, on attempts to disconnect */
456 if (sk
->sk_state
& PPPOX_DEAD
) {
461 if (!opt
->src_addr
.sin_addr
.s_addr
|| !sp
->sa_addr
.pptp
.sin_addr
.s_addr
) {
466 po
->chan
.private = sk
;
467 po
->chan
.ops
= &pptp_chan_ops
;
469 rt
= ip_route_output_ports(&init_net
, &fl4
, sk
,
470 opt
->dst_addr
.sin_addr
.s_addr
,
471 opt
->src_addr
.sin_addr
.s_addr
,
473 IPPROTO_GRE
, RT_CONN_FLAGS(sk
), 0);
475 error
= -EHOSTUNREACH
;
478 sk_setup_caps(sk
, &rt
->dst
);
480 po
->chan
.mtu
= dst_mtu(&rt
->dst
);
482 po
->chan
.mtu
= PPP_MTU
;
484 po
->chan
.mtu
-= PPTP_HEADER_OVERHEAD
;
486 po
->chan
.hdrlen
= 2 + sizeof(struct pptp_gre_header
);
487 error
= ppp_register_channel(&po
->chan
);
489 pr_err("PPTP: failed to register PPP channel (%d)\n", error
);
493 opt
->dst_addr
= sp
->sa_addr
.pptp
;
494 sk
->sk_state
= PPPOX_CONNECTED
;
501 static int pptp_getname(struct socket
*sock
, struct sockaddr
*uaddr
,
502 int *usockaddr_len
, int peer
)
504 int len
= sizeof(struct sockaddr_pppox
);
505 struct sockaddr_pppox sp
;
507 sp
.sa_family
= AF_PPPOX
;
508 sp
.sa_protocol
= PX_PROTO_PPTP
;
509 sp
.sa_addr
.pptp
= pppox_sk(sock
->sk
)->proto
.pptp
.src_addr
;
511 memcpy(uaddr
, &sp
, len
);
513 *usockaddr_len
= len
;
518 static int pptp_release(struct socket
*sock
)
520 struct sock
*sk
= sock
->sk
;
521 struct pppox_sock
*po
;
522 struct pptp_opt
*opt
;
530 if (sock_flag(sk
, SOCK_DEAD
)) {
536 opt
= &po
->proto
.pptp
;
539 pppox_unbind_sock(sk
);
540 sk
->sk_state
= PPPOX_DEAD
;
551 static void pptp_sock_destruct(struct sock
*sk
)
553 if (!(sk
->sk_state
& PPPOX_DEAD
)) {
554 del_chan(pppox_sk(sk
));
555 pppox_unbind_sock(sk
);
557 skb_queue_purge(&sk
->sk_receive_queue
);
560 static int pptp_create(struct net
*net
, struct socket
*sock
)
564 struct pppox_sock
*po
;
565 struct pptp_opt
*opt
;
567 sk
= sk_alloc(net
, PF_PPPOX
, GFP_KERNEL
, &pptp_sk_proto
);
571 sock_init_data(sock
, sk
);
573 sock
->state
= SS_UNCONNECTED
;
574 sock
->ops
= &pptp_ops
;
576 sk
->sk_backlog_rcv
= pptp_rcv_core
;
577 sk
->sk_state
= PPPOX_NONE
;
578 sk
->sk_type
= SOCK_STREAM
;
579 sk
->sk_family
= PF_PPPOX
;
580 sk
->sk_protocol
= PX_PROTO_PPTP
;
581 sk
->sk_destruct
= pptp_sock_destruct
;
584 opt
= &po
->proto
.pptp
;
586 opt
->seq_sent
= 0; opt
->seq_recv
= 0;
587 opt
->ack_recv
= 0; opt
->ack_sent
= 0;
594 static int pptp_ppp_ioctl(struct ppp_channel
*chan
, unsigned int cmd
,
597 struct sock
*sk
= (struct sock
*) chan
->private;
598 struct pppox_sock
*po
= pppox_sk(sk
);
599 struct pptp_opt
*opt
= &po
->proto
.pptp
;
600 void __user
*argp
= (void __user
*)arg
;
601 int __user
*p
= argp
;
607 val
= opt
->ppp_flags
;
608 if (put_user(val
, p
))
613 if (get_user(val
, p
))
615 opt
->ppp_flags
= val
& ~SC_RCV_BITS
;
625 static const struct ppp_channel_ops pptp_chan_ops
= {
626 .start_xmit
= pptp_xmit
,
627 .ioctl
= pptp_ppp_ioctl
,
630 static struct proto pptp_sk_proto __read_mostly
= {
632 .owner
= THIS_MODULE
,
633 .obj_size
= sizeof(struct pppox_sock
),
636 static const struct proto_ops pptp_ops
= {
638 .owner
= THIS_MODULE
,
639 .release
= pptp_release
,
641 .connect
= pptp_connect
,
642 .socketpair
= sock_no_socketpair
,
643 .accept
= sock_no_accept
,
644 .getname
= pptp_getname
,
645 .poll
= sock_no_poll
,
646 .listen
= sock_no_listen
,
647 .shutdown
= sock_no_shutdown
,
648 .setsockopt
= sock_no_setsockopt
,
649 .getsockopt
= sock_no_getsockopt
,
650 .sendmsg
= sock_no_sendmsg
,
651 .recvmsg
= sock_no_recvmsg
,
652 .mmap
= sock_no_mmap
,
653 .ioctl
= pppox_ioctl
,
656 static const struct pppox_proto pppox_pptp_proto
= {
657 .create
= pptp_create
,
658 .owner
= THIS_MODULE
,
661 static const struct gre_protocol gre_pptp_protocol
= {
665 static int __init
pptp_init_module(void)
668 pr_info("PPTP driver version " PPTP_DRIVER_VERSION
"\n");
670 callid_sock
= vzalloc((MAX_CALLID
+ 1) * sizeof(void *));
672 pr_err("PPTP: cann't allocate memory\n");
676 err
= gre_add_protocol(&gre_pptp_protocol
, GREPROTO_PPTP
);
678 pr_err("PPTP: can't add gre protocol\n");
682 err
= proto_register(&pptp_sk_proto
, 0);
684 pr_err("PPTP: can't register sk_proto\n");
685 goto out_gre_del_protocol
;
688 err
= register_pppox_proto(PX_PROTO_PPTP
, &pppox_pptp_proto
);
690 pr_err("PPTP: can't register pppox_proto\n");
691 goto out_unregister_sk_proto
;
696 out_unregister_sk_proto
:
697 proto_unregister(&pptp_sk_proto
);
698 out_gre_del_protocol
:
699 gre_del_protocol(&gre_pptp_protocol
, GREPROTO_PPTP
);
706 static void __exit
pptp_exit_module(void)
708 unregister_pppox_proto(PX_PROTO_PPTP
);
709 proto_unregister(&pptp_sk_proto
);
710 gre_del_protocol(&gre_pptp_protocol
, GREPROTO_PPTP
);
714 module_init(pptp_init_module
);
715 module_exit(pptp_exit_module
);
717 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
718 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
719 MODULE_LICENSE("GPL");