drivers/net/ppp/pptp.c

   1 /*
   2  *  Point-to-Point Tunneling Protocol for Linux
   3  *
   4  *      Authors: Dmitry Kozlov <xeb@mail.ru>
   5  *
   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.
  10  *
  11  */
  12
  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>
  29 #include <linux/in.h>
  30 #include <linux/ip.h>
  31 #include <linux/rcupdate.h>
  32 #include <linux/spinlock.h>
  33
  34 #include <net/sock.h>
  35 #include <net/protocol.h>
  36 #include <net/ip.h>
  37 #include <net/icmp.h>
  38 #include <net/route.h>
  39 #include <net/gre.h>
  40 #include <net/pptp.h>
  41
  42 #include <linux/uaccess.h>
  43
  44 #define PPTP_DRIVER_VERSION "0.8.5"
  45
  46 #define MAX_CALLID 65535
  47
  48 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
  49 static struct pppox_sock __rcu **callid_sock;
  50
  51 static DEFINE_SPINLOCK(chan_lock);
  52
  53 static struct proto pptp_sk_proto __read_mostly;
  54 static const struct ppp_channel_ops pptp_chan_ops;
  55 static const struct proto_ops pptp_ops;
  56
  57 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
  58 {
  59         struct pppox_sock *sock;
  60         struct pptp_opt *opt;
  61
  62         rcu_read_lock();
  63         sock = rcu_dereference(callid_sock[call_id]);
  64         if (sock) {
  65                 opt = &sock->proto.pptp;
  66                 if (opt->dst_addr.sin_addr.s_addr != s_addr)
  67                         sock = NULL;
  68                 else
  69                         sock_hold(sk_pppox(sock));
  70         }
  71         rcu_read_unlock();
  72
  73         return sock;
  74 }
  75
  76 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
  77 {
  78         struct pppox_sock *sock;
  79         struct pptp_opt *opt;
  80         int i;
  81
  82         rcu_read_lock();
  83         i = 1;
  84         for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
  85                 sock = rcu_dereference(callid_sock[i]);
  86                 if (!sock)
  87                         continue;
  88                 opt = &sock->proto.pptp;
  89                 if (opt->dst_addr.call_id == call_id &&
  90                           opt->dst_addr.sin_addr.s_addr == d_addr)
  91                         break;
  92         }
  93         rcu_read_unlock();
  94
  95         return i < MAX_CALLID;
  96 }
  97
  98 static int add_chan(struct pppox_sock *sock,
  99                     struct pptp_addr *sa)
 100 {
 101         static int call_id;
 102
 103         spin_lock(&chan_lock);
 104         if (!sa->call_id)       {
 105                 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
 106                 if (call_id == MAX_CALLID) {
 107                         call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
 108                         if (call_id == MAX_CALLID)
 109                                 goto out_err;
 110                 }
 111                 sa->call_id = call_id;
 112         } else if (test_bit(sa->call_id, callid_bitmap)) {
 113                 goto out_err;
 114         }
 115
 116         sock->proto.pptp.src_addr = *sa;
 117         set_bit(sa->call_id, callid_bitmap);
 118         rcu_assign_pointer(callid_sock[sa->call_id], sock);
 119         spin_unlock(&chan_lock);
 120
 121         return 0;
 122
 123 out_err:
 124         spin_unlock(&chan_lock);
 125         return -1;
 126 }
 127
 128 static void del_chan(struct pppox_sock *sock)
 129 {
 130         spin_lock(&chan_lock);
 131         clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
 132         RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
 133         spin_unlock(&chan_lock);
 134         synchronize_rcu();
 135 }
 136
 137 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 138 {
 139         struct sock *sk = (struct sock *) chan->private;
 140         struct pppox_sock *po = pppox_sk(sk);
 141         struct net *net = sock_net(sk);
 142         struct pptp_opt *opt = &po->proto.pptp;
 143         struct pptp_gre_header *hdr;
 144         unsigned int header_len = sizeof(*hdr);
 145         struct flowi4 fl4;
 146         int islcp;
 147         int len;
 148         unsigned char *data;
 149         __u32 seq_recv;
 150
 151
 152         struct rtable *rt;
 153         struct net_device *tdev;
 154         struct iphdr  *iph;
 155         int    max_headroom;
 156
 157         if (sk_pppox(po)->sk_state & PPPOX_DEAD)
 158                 goto tx_error;
 159
 160         rt = ip_route_output_ports(net, &fl4, NULL,
 161                                    opt->dst_addr.sin_addr.s_addr,
 162                                    opt->src_addr.sin_addr.s_addr,
 163                                    0, 0, IPPROTO_GRE,
 164                                    RT_TOS(0), 0);
 165         if (IS_ERR(rt))
 166                 goto tx_error;
 167
 168         tdev = rt->dst.dev;
 169
 170         max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
 171
 172         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 173                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 174                 if (!new_skb) {
 175                         ip_rt_put(rt);
 176                         goto tx_error;
 177                 }
 178                 if (skb->sk)
 179                         skb_set_owner_w(new_skb, skb->sk);
 180                 consume_skb(skb);
 181                 skb = new_skb;
 182         }
 183
 184         data = skb->data;
 185         islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
 186
 187         /* compress protocol field */
 188         if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
 189                 skb_pull(skb, 1);
 190
 191         /* Put in the address/control bytes if necessary */
 192         if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
 193                 data = skb_push(skb, 2);
 194                 data[0] = PPP_ALLSTATIONS;
 195                 data[1] = PPP_UI;
 196         }
 197
 198         len = skb->len;
 199
 200         seq_recv = opt->seq_recv;
 201
 202         if (opt->ack_sent == seq_recv)
 203                 header_len -= sizeof(hdr->ack);
 204
 205         /* Push down and install GRE header */
 206         skb_push(skb, header_len);
 207         hdr = (struct pptp_gre_header *)(skb->data);
 208
 209         hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
 210         hdr->gre_hd.protocol = GRE_PROTO_PPP;
 211         hdr->call_id = htons(opt->dst_addr.call_id);
 212
 213         hdr->seq = htonl(++opt->seq_sent);
 214         if (opt->ack_sent != seq_recv)  {
 215                 /* send ack with this message */
 216                 hdr->gre_hd.flags |= GRE_ACK;
 217                 hdr->ack  = htonl(seq_recv);
 218                 opt->ack_sent = seq_recv;
 219         }
 220         hdr->payload_len = htons(len);
 221
 222         /*      Push down and install the IP header. */
 223
 224         skb_reset_transport_header(skb);
 225         skb_push(skb, sizeof(*iph));
 226         skb_reset_network_header(skb);
 227         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 228         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
 229
 230         iph =   ip_hdr(skb);
 231         iph->version =  4;
 232         iph->ihl =      sizeof(struct iphdr) >> 2;
 233         if (ip_dont_fragment(sk, &rt->dst))
 234                 iph->frag_off   =       htons(IP_DF);
 235         else
 236                 iph->frag_off   =       0;
 237         iph->protocol = IPPROTO_GRE;
 238         iph->tos      = 0;
 239         iph->daddr    = fl4.daddr;
 240         iph->saddr    = fl4.saddr;
 241         iph->ttl      = ip4_dst_hoplimit(&rt->dst);
 242         iph->tot_len  = htons(skb->len);
 243
 244         skb_dst_drop(skb);
 245         skb_dst_set(skb, &rt->dst);
 246
 247         nf_reset(skb);
 248
 249         skb->ip_summed = CHECKSUM_NONE;
 250         ip_select_ident(net, skb, NULL);
 251         ip_send_check(iph);
 252
 253         ip_local_out(net, skb->sk, skb);
 254         return 1;
 255
 256 tx_error:
 257         kfree_skb(skb);
 258         return 1;
 259 }
 260
 261 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
 262 {
 263         struct pppox_sock *po = pppox_sk(sk);
 264         struct pptp_opt *opt = &po->proto.pptp;
 265         int headersize, payload_len, seq;
 266         __u8 *payload;
 267         struct pptp_gre_header *header;
 268
 269         if (!(sk->sk_state & PPPOX_CONNECTED)) {
 270                 if (sock_queue_rcv_skb(sk, skb))
 271                         goto drop;
 272                 return NET_RX_SUCCESS;
 273         }
 274
 275         header = (struct pptp_gre_header *)(skb->data);
 276         headersize  = sizeof(*header);
 277
 278         /* test if acknowledgement present */
 279         if (GRE_IS_ACK(header->gre_hd.flags)) {
 280                 __u32 ack;
 281
 282                 if (!pskb_may_pull(skb, headersize))
 283                         goto drop;
 284                 header = (struct pptp_gre_header *)(skb->data);
 285
 286                 /* ack in different place if S = 0 */
 287                 ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
 288
 289                 ack = ntohl(ack);
 290
 291                 if (ack > opt->ack_recv)
 292                         opt->ack_recv = ack;
 293                 /* also handle sequence number wrap-around  */
 294                 if (WRAPPED(ack, opt->ack_recv))
 295                         opt->ack_recv = ack;
 296         } else {
 297                 headersize -= sizeof(header->ack);
 298         }
 299         /* test if payload present */
 300         if (!GRE_IS_SEQ(header->gre_hd.flags))
 301                 goto drop;
 302
 303         payload_len = ntohs(header->payload_len);
 304         seq         = ntohl(header->seq);
 305
 306         /* check for incomplete packet (length smaller than expected) */
 307         if (!pskb_may_pull(skb, headersize + payload_len))
 308                 goto drop;
 309
 310         payload = skb->data + headersize;
 311         /* check for expected sequence number */
 312         if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
 313                 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
 314                                 (PPP_PROTOCOL(payload) == PPP_LCP) &&
 315                                 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
 316                         goto allow_packet;
 317         } else {
 318                 opt->seq_recv = seq;
 319 allow_packet:
 320                 skb_pull(skb, headersize);
 321
 322                 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
 323                         /* chop off address/control */
 324                         if (skb->len < 3)
 325                                 goto drop;
 326                         skb_pull(skb, 2);
 327                 }
 328
 329                 if ((*skb->data) & 1) {
 330                         /* protocol is compressed */
 331                         skb_push(skb, 1)[0] = 0;
 332                 }
 333
 334                 skb->ip_summed = CHECKSUM_NONE;
 335                 skb_set_network_header(skb, skb->head-skb->data);
 336                 ppp_input(&po->chan, skb);
 337
 338                 return NET_RX_SUCCESS;
 339         }
 340 drop:
 341         kfree_skb(skb);
 342         return NET_RX_DROP;
 343 }
 344
 345 static int pptp_rcv(struct sk_buff *skb)
 346 {
 347         struct pppox_sock *po;
 348         struct pptp_gre_header *header;
 349         struct iphdr *iph;
 350
 351         if (skb->pkt_type != PACKET_HOST)
 352                 goto drop;
 353
 354         if (!pskb_may_pull(skb, 12))
 355                 goto drop;
 356
 357         iph = ip_hdr(skb);
 358
 359         header = (struct pptp_gre_header *)skb->data;
 360
 361         if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
 362                 GRE_IS_CSUM(header->gre_hd.flags) ||    /* flag CSUM should be clear */
 363                 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
 364                 !GRE_IS_KEY(header->gre_hd.flags) ||    /* flag KEY should be set */
 365                 (header->gre_hd.flags & GRE_FLAGS))     /* flag Recursion Ctrl should be clear */
 366                 /* if invalid, discard this packet */
 367                 goto drop;
 368
 369         po = lookup_chan(htons(header->call_id), iph->saddr);
 370         if (po) {
 371                 skb_dst_drop(skb);
 372                 nf_reset(skb);
 373                 return sk_receive_skb(sk_pppox(po), skb, 0);
 374         }
 375 drop:
 376         kfree_skb(skb);
 377         return NET_RX_DROP;
 378 }
 379
 380 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
 381         int sockaddr_len)
 382 {
 383         struct sock *sk = sock->sk;
 384         struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
 385         struct pppox_sock *po = pppox_sk(sk);
 386         int error = 0;
 387
 388         if (sockaddr_len < sizeof(struct sockaddr_pppox))
 389                 return -EINVAL;
 390
 391         lock_sock(sk);
 392
 393         if (sk->sk_state & PPPOX_DEAD) {
 394                 error = -EALREADY;
 395                 goto out;
 396         }
 397
 398         if (sk->sk_state & PPPOX_BOUND) {
 399                 error = -EBUSY;
 400                 goto out;
 401         }
 402
 403         if (add_chan(po, &sp->sa_addr.pptp))
 404                 error = -EBUSY;
 405         else
 406                 sk->sk_state |= PPPOX_BOUND;
 407
 408 out:
 409         release_sock(sk);
 410         return error;
 411 }
 412
 413 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
 414         int sockaddr_len, int flags)
 415 {
 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;
 420         struct rtable *rt;
 421         struct flowi4 fl4;
 422         int error = 0;
 423
 424         if (sockaddr_len < sizeof(struct sockaddr_pppox))
 425                 return -EINVAL;
 426
 427         if (sp->sa_protocol != PX_PROTO_PPTP)
 428                 return -EINVAL;
 429
 430         if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
 431                 return -EALREADY;
 432
 433         lock_sock(sk);
 434         /* Check for already bound sockets */
 435         if (sk->sk_state & PPPOX_CONNECTED) {
 436                 error = -EBUSY;
 437                 goto end;
 438         }
 439
 440         /* Check for already disconnected sockets, on attempts to disconnect */
 441         if (sk->sk_state & PPPOX_DEAD) {
 442                 error = -EALREADY;
 443                 goto end;
 444         }
 445
 446         if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
 447                 error = -EINVAL;
 448                 goto end;
 449         }
 450
 451         po->chan.private = sk;
 452         po->chan.ops = &pptp_chan_ops;
 453
 454         rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
 455                                    opt->dst_addr.sin_addr.s_addr,
 456                                    opt->src_addr.sin_addr.s_addr,
 457                                    0, 0,
 458                                    IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
 459         if (IS_ERR(rt)) {
 460                 error = -EHOSTUNREACH;
 461                 goto end;
 462         }
 463         sk_setup_caps(sk, &rt->dst);
 464
 465         po->chan.mtu = dst_mtu(&rt->dst);
 466         if (!po->chan.mtu)
 467                 po->chan.mtu = PPP_MRU;
 468         ip_rt_put(rt);
 469         po->chan.mtu -= PPTP_HEADER_OVERHEAD;
 470
 471         po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
 472         error = ppp_register_channel(&po->chan);
 473         if (error) {
 474                 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
 475                 goto end;
 476         }
 477
 478         opt->dst_addr = sp->sa_addr.pptp;
 479         sk->sk_state |= PPPOX_CONNECTED;
 480
 481  end:
 482         release_sock(sk);
 483         return error;
 484 }
 485
 486 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
 487         int *usockaddr_len, int peer)
 488 {
 489         int len = sizeof(struct sockaddr_pppox);
 490         struct sockaddr_pppox sp;
 491
 492         memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
 493
 494         sp.sa_family    = AF_PPPOX;
 495         sp.sa_protocol  = PX_PROTO_PPTP;
 496         sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
 497
 498         memcpy(uaddr, &sp, len);
 499
 500         *usockaddr_len = len;
 501
 502         return 0;
 503 }
 504
 505 static int pptp_release(struct socket *sock)
 506 {
 507         struct sock *sk = sock->sk;
 508         struct pppox_sock *po;
 509         struct pptp_opt *opt;
 510         int error = 0;
 511
 512         if (!sk)
 513                 return 0;
 514
 515         lock_sock(sk);
 516
 517         if (sock_flag(sk, SOCK_DEAD)) {
 518                 release_sock(sk);
 519                 return -EBADF;
 520         }
 521
 522         po = pppox_sk(sk);
 523         opt = &po->proto.pptp;
 524         del_chan(po);
 525
 526         pppox_unbind_sock(sk);
 527         sk->sk_state = PPPOX_DEAD;
 528
 529         sock_orphan(sk);
 530         sock->sk = NULL;
 531
 532         release_sock(sk);
 533         sock_put(sk);
 534
 535         return error;
 536 }
 537
 538 static void pptp_sock_destruct(struct sock *sk)
 539 {
 540         if (!(sk->sk_state & PPPOX_DEAD)) {
 541                 del_chan(pppox_sk(sk));
 542                 pppox_unbind_sock(sk);
 543         }
 544         skb_queue_purge(&sk->sk_receive_queue);
 545 }
 546
 547 static int pptp_create(struct net *net, struct socket *sock, int kern)
 548 {
 549         int error = -ENOMEM;
 550         struct sock *sk;
 551         struct pppox_sock *po;
 552         struct pptp_opt *opt;
 553
 554         sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
 555         if (!sk)
 556                 goto out;
 557
 558         sock_init_data(sock, sk);
 559
 560         sock->state = SS_UNCONNECTED;
 561         sock->ops   = &pptp_ops;
 562
 563         sk->sk_backlog_rcv = pptp_rcv_core;
 564         sk->sk_state       = PPPOX_NONE;
 565         sk->sk_type        = SOCK_STREAM;
 566         sk->sk_family      = PF_PPPOX;
 567         sk->sk_protocol    = PX_PROTO_PPTP;
 568         sk->sk_destruct    = pptp_sock_destruct;
 569
 570         po = pppox_sk(sk);
 571         opt = &po->proto.pptp;
 572
 573         opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
 574         opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
 575
 576         error = 0;
 577 out:
 578         return error;
 579 }
 580
 581 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
 582         unsigned long arg)
 583 {
 584         struct sock *sk = (struct sock *) chan->private;
 585         struct pppox_sock *po = pppox_sk(sk);
 586         struct pptp_opt *opt = &po->proto.pptp;
 587         void __user *argp = (void __user *)arg;
 588         int __user *p = argp;
 589         int err, val;
 590
 591         err = -EFAULT;
 592         switch (cmd) {
 593         case PPPIOCGFLAGS:
 594                 val = opt->ppp_flags;
 595                 if (put_user(val, p))
 596                         break;
 597                 err = 0;
 598                 break;
 599         case PPPIOCSFLAGS:
 600                 if (get_user(val, p))
 601                         break;
 602                 opt->ppp_flags = val & ~SC_RCV_BITS;
 603                 err = 0;
 604                 break;
 605         default:
 606                 err = -ENOTTY;
 607         }
 608
 609         return err;
 610 }
 611
 612 static const struct ppp_channel_ops pptp_chan_ops = {
 613         .start_xmit = pptp_xmit,
 614         .ioctl      = pptp_ppp_ioctl,
 615 };
 616
 617 static struct proto pptp_sk_proto __read_mostly = {
 618         .name     = "PPTP",
 619         .owner    = THIS_MODULE,
 620         .obj_size = sizeof(struct pppox_sock),
 621 };
 622
 623 static const struct proto_ops pptp_ops = {
 624         .family     = AF_PPPOX,
 625         .owner      = THIS_MODULE,
 626         .release    = pptp_release,
 627         .bind       = pptp_bind,
 628         .connect    = pptp_connect,
 629         .socketpair = sock_no_socketpair,
 630         .accept     = sock_no_accept,
 631         .getname    = pptp_getname,
 632         .poll       = sock_no_poll,
 633         .listen     = sock_no_listen,
 634         .shutdown   = sock_no_shutdown,
 635         .setsockopt = sock_no_setsockopt,
 636         .getsockopt = sock_no_getsockopt,
 637         .sendmsg    = sock_no_sendmsg,
 638         .recvmsg    = sock_no_recvmsg,
 639         .mmap       = sock_no_mmap,
 640         .ioctl      = pppox_ioctl,
 641 };
 642
 643 static const struct pppox_proto pppox_pptp_proto = {
 644         .create = pptp_create,
 645         .owner  = THIS_MODULE,
 646 };
 647
 648 static const struct gre_protocol gre_pptp_protocol = {
 649         .handler = pptp_rcv,
 650 };
 651
 652 static int __init pptp_init_module(void)
 653 {
 654         int err = 0;
 655         pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
 656
 657         callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *));
 658         if (!callid_sock)
 659                 return -ENOMEM;
 660
 661         err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
 662         if (err) {
 663                 pr_err("PPTP: can't add gre protocol\n");
 664                 goto out_mem_free;
 665         }
 666
 667         err = proto_register(&pptp_sk_proto, 0);
 668         if (err) {
 669                 pr_err("PPTP: can't register sk_proto\n");
 670                 goto out_gre_del_protocol;
 671         }
 672
 673         err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
 674         if (err) {
 675                 pr_err("PPTP: can't register pppox_proto\n");
 676                 goto out_unregister_sk_proto;
 677         }
 678
 679         return 0;
 680
 681 out_unregister_sk_proto:
 682         proto_unregister(&pptp_sk_proto);
 683 out_gre_del_protocol:
 684         gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
 685 out_mem_free:
 686         vfree(callid_sock);
 687
 688         return err;
 689 }
 690
 691 static void __exit pptp_exit_module(void)
 692 {
 693         unregister_pppox_proto(PX_PROTO_PPTP);
 694         proto_unregister(&pptp_sk_proto);
 695         gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
 696         vfree(callid_sock);
 697 }
 698
 699 module_init(pptp_init_module);
 700 module_exit(pptp_exit_module);
 701
 702 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
 703 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
 704 MODULE_LICENSE("GPL");
 705 MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);