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 }
 135
 136 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 137 {
 138         struct sock *sk = (struct sock *) chan->private;
 139         struct pppox_sock *po = pppox_sk(sk);
 140         struct net *net = sock_net(sk);
 141         struct pptp_opt *opt = &po->proto.pptp;
 142         struct pptp_gre_header *hdr;
 143         unsigned int header_len = sizeof(*hdr);
 144         struct flowi4 fl4;
 145         int islcp;
 146         int len;
 147         unsigned char *data;
 148         __u32 seq_recv;
 149
 150
 151         struct rtable *rt;
 152         struct net_device *tdev;
 153         struct iphdr  *iph;
 154         int    max_headroom;
 155
 156         if (sk_pppox(po)->sk_state & PPPOX_DEAD)
 157                 goto tx_error;
 158
 159         rt = ip_route_output_ports(net, &fl4, NULL,
 160                                    opt->dst_addr.sin_addr.s_addr,
 161                                    opt->src_addr.sin_addr.s_addr,
 162                                    0, 0, IPPROTO_GRE,
 163                                    RT_TOS(0), 0);
 164         if (IS_ERR(rt))
 165                 goto tx_error;
 166
 167         tdev = rt->dst.dev;
 168
 169         max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
 170
 171         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 172                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 173                 if (!new_skb) {
 174                         ip_rt_put(rt);
 175                         goto tx_error;
 176                 }
 177                 if (skb->sk)
 178                         skb_set_owner_w(new_skb, skb->sk);
 179                 consume_skb(skb);
 180                 skb = new_skb;
 181         }
 182
 183         data = skb->data;
 184         islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
 185
 186         /* compress protocol field */
 187         if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
 188                 skb_pull(skb, 1);
 189
 190         /* Put in the address/control bytes if necessary */
 191         if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
 192                 data = skb_push(skb, 2);
 193                 data[0] = PPP_ALLSTATIONS;
 194                 data[1] = PPP_UI;
 195         }
 196
 197         len = skb->len;
 198
 199         seq_recv = opt->seq_recv;
 200
 201         if (opt->ack_sent == seq_recv)
 202                 header_len -= sizeof(hdr->ack);
 203
 204         /* Push down and install GRE header */
 205         skb_push(skb, header_len);
 206         hdr = (struct pptp_gre_header *)(skb->data);
 207
 208         hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
 209         hdr->gre_hd.protocol = GRE_PROTO_PPP;
 210         hdr->call_id = htons(opt->dst_addr.call_id);
 211
 212         hdr->seq = htonl(++opt->seq_sent);
 213         if (opt->ack_sent != seq_recv)  {
 214                 /* send ack with this message */
 215                 hdr->gre_hd.flags |= GRE_ACK;
 216                 hdr->ack  = htonl(seq_recv);
 217                 opt->ack_sent = seq_recv;
 218         }
 219         hdr->payload_len = htons(len);
 220
 221         /*      Push down and install the IP header. */
 222
 223         skb_reset_transport_header(skb);
 224         skb_push(skb, sizeof(*iph));
 225         skb_reset_network_header(skb);
 226         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 227         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
 228
 229         iph =   ip_hdr(skb);
 230         iph->version =  4;
 231         iph->ihl =      sizeof(struct iphdr) >> 2;
 232         if (ip_dont_fragment(sk, &rt->dst))
 233                 iph->frag_off   =       htons(IP_DF);
 234         else
 235                 iph->frag_off   =       0;
 236         iph->protocol = IPPROTO_GRE;
 237         iph->tos      = 0;
 238         iph->daddr    = fl4.daddr;
 239         iph->saddr    = fl4.saddr;
 240         iph->ttl      = ip4_dst_hoplimit(&rt->dst);
 241         iph->tot_len  = htons(skb->len);
 242
 243         skb_dst_drop(skb);
 244         skb_dst_set(skb, &rt->dst);
 245
 246         nf_reset(skb);
 247
 248         skb->ip_summed = CHECKSUM_NONE;
 249         ip_select_ident(net, skb, NULL);
 250         ip_send_check(iph);
 251
 252         ip_local_out(net, skb->sk, skb);
 253         return 1;
 254
 255 tx_error:
 256         kfree_skb(skb);
 257         return 1;
 258 }
 259
 260 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
 261 {
 262         struct pppox_sock *po = pppox_sk(sk);
 263         struct pptp_opt *opt = &po->proto.pptp;
 264         int headersize, payload_len, seq;
 265         __u8 *payload;
 266         struct pptp_gre_header *header;
 267
 268         if (!(sk->sk_state & PPPOX_CONNECTED)) {
 269                 if (sock_queue_rcv_skb(sk, skb))
 270                         goto drop;
 271                 return NET_RX_SUCCESS;
 272         }
 273
 274         header = (struct pptp_gre_header *)(skb->data);
 275         headersize  = sizeof(*header);
 276
 277         /* test if acknowledgement present */
 278         if (GRE_IS_ACK(header->gre_hd.flags)) {
 279                 __u32 ack;
 280
 281                 if (!pskb_may_pull(skb, headersize))
 282                         goto drop;
 283                 header = (struct pptp_gre_header *)(skb->data);
 284
 285                 /* ack in different place if S = 0 */
 286                 ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
 287
 288                 ack = ntohl(ack);
 289
 290                 if (ack > opt->ack_recv)
 291                         opt->ack_recv = ack;
 292                 /* also handle sequence number wrap-around  */
 293                 if (WRAPPED(ack, opt->ack_recv))
 294                         opt->ack_recv = ack;
 295         } else {
 296                 headersize -= sizeof(header->ack);
 297         }
 298         /* test if payload present */
 299         if (!GRE_IS_SEQ(header->gre_hd.flags))
 300                 goto drop;
 301
 302         payload_len = ntohs(header->payload_len);
 303         seq         = ntohl(header->seq);
 304
 305         /* check for incomplete packet (length smaller than expected) */
 306         if (!pskb_may_pull(skb, headersize + payload_len))
 307                 goto drop;
 308
 309         payload = skb->data + headersize;
 310         /* check for expected sequence number */
 311         if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
 312                 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
 313                                 (PPP_PROTOCOL(payload) == PPP_LCP) &&
 314                                 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
 315                         goto allow_packet;
 316         } else {
 317                 opt->seq_recv = seq;
 318 allow_packet:
 319                 skb_pull(skb, headersize);
 320
 321                 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
 322                         /* chop off address/control */
 323                         if (skb->len < 3)
 324                                 goto drop;
 325                         skb_pull(skb, 2);
 326                 }
 327
 328                 skb->ip_summed = CHECKSUM_NONE;
 329                 skb_set_network_header(skb, skb->head-skb->data);
 330                 ppp_input(&po->chan, skb);
 331
 332                 return NET_RX_SUCCESS;
 333         }
 334 drop:
 335         kfree_skb(skb);
 336         return NET_RX_DROP;
 337 }
 338
 339 static int pptp_rcv(struct sk_buff *skb)
 340 {
 341         struct pppox_sock *po;
 342         struct pptp_gre_header *header;
 343         struct iphdr *iph;
 344
 345         if (skb->pkt_type != PACKET_HOST)
 346                 goto drop;
 347
 348         if (!pskb_may_pull(skb, 12))
 349                 goto drop;
 350
 351         iph = ip_hdr(skb);
 352
 353         header = (struct pptp_gre_header *)skb->data;
 354
 355         if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
 356                 GRE_IS_CSUM(header->gre_hd.flags) ||    /* flag CSUM should be clear */
 357                 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
 358                 !GRE_IS_KEY(header->gre_hd.flags) ||    /* flag KEY should be set */
 359                 (header->gre_hd.flags & GRE_FLAGS))     /* flag Recursion Ctrl should be clear */
 360                 /* if invalid, discard this packet */
 361                 goto drop;
 362
 363         po = lookup_chan(htons(header->call_id), iph->saddr);
 364         if (po) {
 365                 skb_dst_drop(skb);
 366                 nf_reset(skb);
 367                 return sk_receive_skb(sk_pppox(po), skb, 0);
 368         }
 369 drop:
 370         kfree_skb(skb);
 371         return NET_RX_DROP;
 372 }
 373
 374 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
 375         int sockaddr_len)
 376 {
 377         struct sock *sk = sock->sk;
 378         struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
 379         struct pppox_sock *po = pppox_sk(sk);
 380         int error = 0;
 381
 382         if (sockaddr_len < sizeof(struct sockaddr_pppox))
 383                 return -EINVAL;
 384
 385         lock_sock(sk);
 386
 387         if (sk->sk_state & PPPOX_DEAD) {
 388                 error = -EALREADY;
 389                 goto out;
 390         }
 391
 392         if (sk->sk_state & PPPOX_BOUND) {
 393                 error = -EBUSY;
 394                 goto out;
 395         }
 396
 397         if (add_chan(po, &sp->sa_addr.pptp))
 398                 error = -EBUSY;
 399         else
 400                 sk->sk_state |= PPPOX_BOUND;
 401
 402 out:
 403         release_sock(sk);
 404         return error;
 405 }
 406
 407 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
 408         int sockaddr_len, int flags)
 409 {
 410         struct sock *sk = sock->sk;
 411         struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
 412         struct pppox_sock *po = pppox_sk(sk);
 413         struct pptp_opt *opt = &po->proto.pptp;
 414         struct rtable *rt;
 415         struct flowi4 fl4;
 416         int error = 0;
 417
 418         if (sockaddr_len < sizeof(struct sockaddr_pppox))
 419                 return -EINVAL;
 420
 421         if (sp->sa_protocol != PX_PROTO_PPTP)
 422                 return -EINVAL;
 423
 424         if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
 425                 return -EALREADY;
 426
 427         lock_sock(sk);
 428         /* Check for already bound sockets */
 429         if (sk->sk_state & PPPOX_CONNECTED) {
 430                 error = -EBUSY;
 431                 goto end;
 432         }
 433
 434         /* Check for already disconnected sockets, on attempts to disconnect */
 435         if (sk->sk_state & PPPOX_DEAD) {
 436                 error = -EALREADY;
 437                 goto end;
 438         }
 439
 440         if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
 441                 error = -EINVAL;
 442                 goto end;
 443         }
 444
 445         po->chan.private = sk;
 446         po->chan.ops = &pptp_chan_ops;
 447
 448         rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
 449                                    opt->dst_addr.sin_addr.s_addr,
 450                                    opt->src_addr.sin_addr.s_addr,
 451                                    0, 0,
 452                                    IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
 453         if (IS_ERR(rt)) {
 454                 error = -EHOSTUNREACH;
 455                 goto end;
 456         }
 457         sk_setup_caps(sk, &rt->dst);
 458
 459         po->chan.mtu = dst_mtu(&rt->dst);
 460         if (!po->chan.mtu)
 461                 po->chan.mtu = PPP_MRU;
 462         po->chan.mtu -= PPTP_HEADER_OVERHEAD;
 463
 464         po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
 465         error = ppp_register_channel(&po->chan);
 466         if (error) {
 467                 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
 468                 goto end;
 469         }
 470
 471         opt->dst_addr = sp->sa_addr.pptp;
 472         sk->sk_state |= PPPOX_CONNECTED;
 473
 474  end:
 475         release_sock(sk);
 476         return error;
 477 }
 478
 479 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
 480         int peer)
 481 {
 482         int len = sizeof(struct sockaddr_pppox);
 483         struct sockaddr_pppox sp;
 484
 485         memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
 486
 487         sp.sa_family    = AF_PPPOX;
 488         sp.sa_protocol  = PX_PROTO_PPTP;
 489         sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
 490
 491         memcpy(uaddr, &sp, len);
 492
 493         return len;
 494 }
 495
 496 static int pptp_release(struct socket *sock)
 497 {
 498         struct sock *sk = sock->sk;
 499         struct pppox_sock *po;
 500         int error = 0;
 501
 502         if (!sk)
 503                 return 0;
 504
 505         lock_sock(sk);
 506
 507         if (sock_flag(sk, SOCK_DEAD)) {
 508                 release_sock(sk);
 509                 return -EBADF;
 510         }
 511
 512         po = pppox_sk(sk);
 513         del_chan(po);
 514         synchronize_rcu();
 515
 516         pppox_unbind_sock(sk);
 517         sk->sk_state = PPPOX_DEAD;
 518
 519         sock_orphan(sk);
 520         sock->sk = NULL;
 521
 522         release_sock(sk);
 523         sock_put(sk);
 524
 525         return error;
 526 }
 527
 528 static void pptp_sock_destruct(struct sock *sk)
 529 {
 530         if (!(sk->sk_state & PPPOX_DEAD)) {
 531                 del_chan(pppox_sk(sk));
 532                 pppox_unbind_sock(sk);
 533         }
 534         skb_queue_purge(&sk->sk_receive_queue);
 535 }
 536
 537 static int pptp_create(struct net *net, struct socket *sock, int kern)
 538 {
 539         int error = -ENOMEM;
 540         struct sock *sk;
 541         struct pppox_sock *po;
 542         struct pptp_opt *opt;
 543
 544         sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
 545         if (!sk)
 546                 goto out;
 547
 548         sock_init_data(sock, sk);
 549
 550         sock->state = SS_UNCONNECTED;
 551         sock->ops   = &pptp_ops;
 552
 553         sk->sk_backlog_rcv = pptp_rcv_core;
 554         sk->sk_state       = PPPOX_NONE;
 555         sk->sk_type        = SOCK_STREAM;
 556         sk->sk_family      = PF_PPPOX;
 557         sk->sk_protocol    = PX_PROTO_PPTP;
 558         sk->sk_destruct    = pptp_sock_destruct;
 559
 560         po = pppox_sk(sk);
 561         opt = &po->proto.pptp;
 562
 563         opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
 564         opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
 565
 566         error = 0;
 567 out:
 568         return error;
 569 }
 570
 571 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
 572         unsigned long arg)
 573 {
 574         struct sock *sk = (struct sock *) chan->private;
 575         struct pppox_sock *po = pppox_sk(sk);
 576         struct pptp_opt *opt = &po->proto.pptp;
 577         void __user *argp = (void __user *)arg;
 578         int __user *p = argp;
 579         int err, val;
 580
 581         err = -EFAULT;
 582         switch (cmd) {
 583         case PPPIOCGFLAGS:
 584                 val = opt->ppp_flags;
 585                 if (put_user(val, p))
 586                         break;
 587                 err = 0;
 588                 break;
 589         case PPPIOCSFLAGS:
 590                 if (get_user(val, p))
 591                         break;
 592                 opt->ppp_flags = val & ~SC_RCV_BITS;
 593                 err = 0;
 594                 break;
 595         default:
 596                 err = -ENOTTY;
 597         }
 598
 599         return err;
 600 }
 601
 602 static const struct ppp_channel_ops pptp_chan_ops = {
 603         .start_xmit = pptp_xmit,
 604         .ioctl      = pptp_ppp_ioctl,
 605 };
 606
 607 static struct proto pptp_sk_proto __read_mostly = {
 608         .name     = "PPTP",
 609         .owner    = THIS_MODULE,
 610         .obj_size = sizeof(struct pppox_sock),
 611 };
 612
 613 static const struct proto_ops pptp_ops = {
 614         .family     = AF_PPPOX,
 615         .owner      = THIS_MODULE,
 616         .release    = pptp_release,
 617         .bind       = pptp_bind,
 618         .connect    = pptp_connect,
 619         .socketpair = sock_no_socketpair,
 620         .accept     = sock_no_accept,
 621         .getname    = pptp_getname,
 622         .listen     = sock_no_listen,
 623         .shutdown   = sock_no_shutdown,
 624         .setsockopt = sock_no_setsockopt,
 625         .getsockopt = sock_no_getsockopt,
 626         .sendmsg    = sock_no_sendmsg,
 627         .recvmsg    = sock_no_recvmsg,
 628         .mmap       = sock_no_mmap,
 629         .ioctl      = pppox_ioctl,
 630 };
 631
 632 static const struct pppox_proto pppox_pptp_proto = {
 633         .create = pptp_create,
 634         .owner  = THIS_MODULE,
 635 };
 636
 637 static const struct gre_protocol gre_pptp_protocol = {
 638         .handler = pptp_rcv,
 639 };
 640
 641 static int __init pptp_init_module(void)
 642 {
 643         int err = 0;
 644         pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
 645
 646         callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
 647         if (!callid_sock)
 648                 return -ENOMEM;
 649
 650         err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
 651         if (err) {
 652                 pr_err("PPTP: can't add gre protocol\n");
 653                 goto out_mem_free;
 654         }
 655
 656         err = proto_register(&pptp_sk_proto, 0);
 657         if (err) {
 658                 pr_err("PPTP: can't register sk_proto\n");
 659                 goto out_gre_del_protocol;
 660         }
 661
 662         err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
 663         if (err) {
 664                 pr_err("PPTP: can't register pppox_proto\n");
 665                 goto out_unregister_sk_proto;
 666         }
 667
 668         return 0;
 669
 670 out_unregister_sk_proto:
 671         proto_unregister(&pptp_sk_proto);
 672 out_gre_del_protocol:
 673         gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
 674 out_mem_free:
 675         vfree(callid_sock);
 676
 677         return err;
 678 }
 679
 680 static void __exit pptp_exit_module(void)
 681 {
 682         unregister_pppox_proto(PX_PROTO_PPTP);
 683         proto_unregister(&pptp_sk_proto);
 684         gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
 685         vfree(callid_sock);
 686 }
 687
 688 module_init(pptp_init_module);
 689 module_exit(pptp_exit_module);
 690
 691 MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
 692 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
 693 MODULE_LICENSE("GPL");
 694 MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);