drivers/net/ppp/pptp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Point-to-Point Tunneling Protocol for Linux
   4  *
   5  *      Authors: Dmitry Kozlov <xeb@mail.ru>
   6  */
   7
   8 #include <linux/string.h>
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/errno.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/net.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/init.h>
  18 #include <linux/ppp_channel.h>
  19 #include <linux/ppp_defs.h>
  20 #include <linux/if_pppox.h>
  21 #include <linux/ppp-ioctl.h>
  22 #include <linux/notifier.h>
  23 #include <linux/file.h>
  24 #include <linux/in.h>
  25 #include <linux/ip.h>
  26 #include <linux/rcupdate.h>
  27 #include <linux/spinlock.h>
  28
  29 #include <net/sock.h>
  30 #include <net/protocol.h>
  31 #include <net/ip.h>
  32 #include <net/icmp.h>
  33 #include <net/route.h>
  34 #include <net/gre.h>
  35 #include <net/pptp.h>
  36
  37 #include <linux/uaccess.h>
  38
  39 #define PPTP_DRIVER_VERSION "0.8.5"
  40
  41 #define MAX_CALLID 65535
  42
  43 static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
  44 static struct pppox_sock __rcu **callid_sock;
  45
  46 static DEFINE_SPINLOCK(chan_lock);
  47
  48 static struct proto pptp_sk_proto __read_mostly;
  49 static const struct ppp_channel_ops pptp_chan_ops;
  50 static const struct proto_ops pptp_ops;
  51
  52 static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
  53 {
  54         struct pppox_sock *sock;
  55         struct pptp_opt *opt;
  56
  57         rcu_read_lock();
  58         sock = rcu_dereference(callid_sock[call_id]);
  59         if (sock) {
  60                 opt = &sock->proto.pptp;
  61                 if (opt->dst_addr.sin_addr.s_addr != s_addr)
  62                         sock = NULL;
  63                 else
  64                         sock_hold(sk_pppox(sock));
  65         }
  66         rcu_read_unlock();
  67
  68         return sock;
  69 }
  70
  71 static int lookup_chan_dst(u16 call_id, __be32 d_addr)
  72 {
  73         struct pppox_sock *sock;
  74         struct pptp_opt *opt;
  75         int i;
  76
  77         rcu_read_lock();
  78         i = 1;
  79         for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
  80                 sock = rcu_dereference(callid_sock[i]);
  81                 if (!sock)
  82                         continue;
  83                 opt = &sock->proto.pptp;
  84                 if (opt->dst_addr.call_id == call_id &&
  85                           opt->dst_addr.sin_addr.s_addr == d_addr)
  86                         break;
  87         }
  88         rcu_read_unlock();
  89
  90         return i < MAX_CALLID;
  91 }
  92
  93 static int add_chan(struct pppox_sock *sock,
  94                     struct pptp_addr *sa)
  95 {
  96         static int call_id;
  97
  98         spin_lock(&chan_lock);
  99         if (!sa->call_id)       {
 100                 call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
 101                 if (call_id == MAX_CALLID) {
 102                         call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
 103                         if (call_id == MAX_CALLID)
 104                                 goto out_err;
 105                 }
 106                 sa->call_id = call_id;
 107         } else if (test_bit(sa->call_id, callid_bitmap)) {
 108                 goto out_err;
 109         }
 110
 111         sock->proto.pptp.src_addr = *sa;
 112         set_bit(sa->call_id, callid_bitmap);
 113         rcu_assign_pointer(callid_sock[sa->call_id], sock);
 114         spin_unlock(&chan_lock);
 115
 116         return 0;
 117
 118 out_err:
 119         spin_unlock(&chan_lock);
 120         return -1;
 121 }
 122
 123 static void del_chan(struct pppox_sock *sock)
 124 {
 125         spin_lock(&chan_lock);
 126         clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
 127         RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
 128         spin_unlock(&chan_lock);
 129 }
 130
 131 static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 132 {
 133         struct sock *sk = (struct sock *) chan->private;
 134         struct pppox_sock *po = pppox_sk(sk);
 135         struct net *net = sock_net(sk);
 136         struct pptp_opt *opt = &po->proto.pptp;
 137         struct pptp_gre_header *hdr;
 138         unsigned int header_len = sizeof(*hdr);
 139         struct flowi4 fl4;
 140         int islcp;
 141         int len;
 142         unsigned char *data;
 143         __u32 seq_recv;
 144
 145
 146         struct rtable *rt;
 147         struct net_device *tdev;
 148         struct iphdr  *iph;
 149         int    max_headroom;
 150
 151         if (sk_pppox(po)->sk_state & PPPOX_DEAD)
 152                 goto tx_error;
 153
 154         rt = ip_route_output_ports(net, &fl4, NULL,
 155                                    opt->dst_addr.sin_addr.s_addr,
 156                                    opt->src_addr.sin_addr.s_addr,
 157                                    0, 0, IPPROTO_GRE,
 158                                    RT_TOS(0), sk->sk_bound_dev_if);
 159         if (IS_ERR(rt))
 160                 goto tx_error;
 161
 162         tdev = rt->dst.dev;
 163
 164         max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
 165
 166         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 167                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 168                 if (!new_skb) {
 169                         ip_rt_put(rt);
 170                         goto tx_error;
 171                 }
 172                 if (skb->sk)
 173                         skb_set_owner_w(new_skb, skb->sk);
 174                 consume_skb(skb);
 175                 skb = new_skb;
 176         }
 177
 178         data = skb->data;
 179         islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
 180
 181         /* compress protocol field */
 182         if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
 183                 skb_pull(skb, 1);
 184
 185         /* Put in the address/control bytes if necessary */
 186         if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
 187                 data = skb_push(skb, 2);
 188                 data[0] = PPP_ALLSTATIONS;
 189                 data[1] = PPP_UI;
 190         }
 191
 192         len = skb->len;
 193
 194         seq_recv = opt->seq_recv;
 195
 196         if (opt->ack_sent == seq_recv)
 197                 header_len -= sizeof(hdr->ack);
 198
 199         /* Push down and install GRE header */
 200         skb_push(skb, header_len);
 201         hdr = (struct pptp_gre_header *)(skb->data);
 202
 203         hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
 204         hdr->gre_hd.protocol = GRE_PROTO_PPP;
 205         hdr->call_id = htons(opt->dst_addr.call_id);
 206
 207         hdr->seq = htonl(++opt->seq_sent);
 208         if (opt->ack_sent != seq_recv)  {
 209                 /* send ack with this message */
 210                 hdr->gre_hd.flags |= GRE_ACK;
 211                 hdr->ack  = htonl(seq_recv);
 212                 opt->ack_sent = seq_recv;
 213         }
 214         hdr->payload_len = htons(len);
 215
 216         /*      Push down and install the IP header. */
 217
 218         skb_reset_transport_header(skb);
 219         skb_push(skb, sizeof(*iph));
 220         skb_reset_network_header(skb);
 221         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 222         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
 223
 224         iph =   ip_hdr(skb);
 225         iph->version =  4;
 226         iph->ihl =      sizeof(struct iphdr) >> 2;
 227         if (ip_dont_fragment(sk, &rt->dst))
 228                 iph->frag_off   =       htons(IP_DF);
 229         else
 230                 iph->frag_off   =       0;
 231         iph->protocol = IPPROTO_GRE;
 232         iph->tos      = 0;
 233         iph->daddr    = fl4.daddr;
 234         iph->saddr    = fl4.saddr;
 235         iph->ttl      = ip4_dst_hoplimit(&rt->dst);
 236         iph->tot_len  = htons(skb->len);
 237
 238         skb_dst_drop(skb);
 239         skb_dst_set(skb, &rt->dst);
 240
 241         nf_reset_ct(skb);
 242
 243         skb->ip_summed = CHECKSUM_NONE;
 244         ip_select_ident(net, skb, NULL);
 245         ip_send_check(iph);
 246
 247         ip_local_out(net, skb->sk, skb);
 248         return 1;
 249
 250 tx_error:
 251         kfree_skb(skb);
 252         return 1;
 253 }
 254
 255 static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
 256 {
 257         struct pppox_sock *po = pppox_sk(sk);
 258         struct pptp_opt *opt = &po->proto.pptp;
 259         int headersize, payload_len, seq;
 260         __u8 *payload;
 261         struct pptp_gre_header *header;
 262
 263         if (!(sk->sk_state & PPPOX_CONNECTED)) {
 264                 if (sock_queue_rcv_skb(sk, skb))
 265                         goto drop;
 266                 return NET_RX_SUCCESS;
 267         }
 268
 269         header = (struct pptp_gre_header *)(skb->data);
 270         headersize  = sizeof(*header);
 271
 272         /* test if acknowledgement present */
 273         if (GRE_IS_ACK(header->gre_hd.flags)) {
 274                 __u32 ack;
 275
 276                 if (!pskb_may_pull(skb, headersize))
 277                         goto drop;
 278                 header = (struct pptp_gre_header *)(skb->data);
 279
 280                 /* ack in different place if S = 0 */
 281                 ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
 282
 283                 ack = ntohl(ack);
 284
 285                 if (ack > opt->ack_recv)
 286                         opt->ack_recv = ack;
 287                 /* also handle sequence number wrap-around  */
 288                 if (WRAPPED(ack, opt->ack_recv))
 289                         opt->ack_recv = ack;
 290         } else {
 291                 headersize -= sizeof(header->ack);
 292         }
 293         /* test if payload present */
 294         if (!GRE_IS_SEQ(header->gre_hd.flags))
 295                 goto drop;
 296
 297         payload_len = ntohs(header->payload_len);
 298         seq         = ntohl(header->seq);
 299
 300         /* check for incomplete packet (length smaller than expected) */
 301         if (!pskb_may_pull(skb, headersize + payload_len))
 302                 goto drop;
 303
 304         payload = skb->data + headersize;
 305         /* check for expected sequence number */
 306         if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
 307                 if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
 308                                 (PPP_PROTOCOL(payload) == PPP_LCP) &&
 309                                 ((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
 310                         goto allow_packet;
 311         } else {
 312                 opt->seq_recv = seq;
 313 allow_packet:
 314                 skb_pull(skb, headersize);
 315
 316                 if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
 317                         /* chop off address/control */
 318                         if (skb->len < 3)
 319                                 goto drop;
 320                         skb_pull(skb, 2);
 321                 }
 322
 323                 skb->ip_summed = CHECKSUM_NONE;
 324                 skb_set_network_header(skb, skb->head-skb->data);
 325                 ppp_input(&po->chan, skb);
 326
 327                 return NET_RX_SUCCESS;
 328         }
 329 drop:
 330         kfree_skb(skb);
 331         return NET_RX_DROP;
 332 }
 333
 334 static int pptp_rcv(struct sk_buff *skb)
 335 {
 336         struct pppox_sock *po;
 337         struct pptp_gre_header *header;
 338         struct iphdr *iph;
 339
 340         if (skb->pkt_type != PACKET_HOST)
 341                 goto drop;
 342
 343         if (!pskb_may_pull(skb, 12))
 344                 goto drop;
 345
 346         iph = ip_hdr(skb);
 347
 348         header = (struct pptp_gre_header *)skb->data;
 349
 350         if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
 351                 GRE_IS_CSUM(header->gre_hd.flags) ||    /* flag CSUM should be clear */
 352                 GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
 353                 !GRE_IS_KEY(header->gre_hd.flags) ||    /* flag KEY should be set */
 354                 (header->gre_hd.flags & GRE_FLAGS))     /* flag Recursion Ctrl should be clear */
 355                 /* if invalid, discard this packet */
 356                 goto drop;
 357
 358         po = lookup_chan(htons(header->call_id), iph->saddr);
 359         if (po) {
 360                 skb_dst_drop(skb);
 361                 nf_reset_ct(skb);
 362                 return sk_receive_skb(sk_pppox(po), skb, 0);
 363         }
 364 drop:
 365         kfree_skb(skb);
 366         return NET_RX_DROP;
 367 }
 368
 369 static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
 370         int sockaddr_len)
 371 {
 372         struct sock *sk = sock->sk;
 373         struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
 374         struct pppox_sock *po = pppox_sk(sk);
 375         int error = 0;
 376
 377         if (sockaddr_len < sizeof(struct sockaddr_pppox))
 378                 return -EINVAL;
 379
 380         lock_sock(sk);
 381
 382         if (sk->sk_state & PPPOX_DEAD) {
 383                 error = -EALREADY;
 384                 goto out;
 385         }
 386
 387         if (sk->sk_state & PPPOX_BOUND) {
 388                 error = -EBUSY;
 389                 goto out;
 390         }
 391
 392         if (add_chan(po, &sp->sa_addr.pptp))
 393                 error = -EBUSY;
 394         else
 395                 sk->sk_state |= PPPOX_BOUND;
 396
 397 out:
 398         release_sock(sk);
 399         return error;
 400 }
 401
 402 static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
 403         int sockaddr_len, int flags)
 404 {
 405         struct sock *sk = sock->sk;
 406         struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
 407         struct pppox_sock *po = pppox_sk(sk);
 408         struct pptp_opt *opt = &po->proto.pptp;
 409         struct rtable *rt;
 410         struct flowi4 fl4;
 411         int error = 0;
 412
 413         if (sockaddr_len < sizeof(struct sockaddr_pppox))
 414                 return -EINVAL;
 415
 416         if (sp->sa_protocol != PX_PROTO_PPTP)
 417                 return -EINVAL;
 418
 419         if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
 420                 return -EALREADY;
 421
 422         lock_sock(sk);
 423         /* Check for already bound sockets */
 424         if (sk->sk_state & PPPOX_CONNECTED) {
 425                 error = -EBUSY;
 426                 goto end;
 427         }
 428
 429         /* Check for already disconnected sockets, on attempts to disconnect */
 430         if (sk->sk_state & PPPOX_DEAD) {
 431                 error = -EALREADY;
 432                 goto end;
 433         }
 434
 435         if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
 436                 error = -EINVAL;
 437                 goto end;
 438         }
 439
 440         po->chan.private = sk;
 441         po->chan.ops = &pptp_chan_ops;
 442
 443         rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
 444                                    opt->dst_addr.sin_addr.s_addr,
 445                                    opt->src_addr.sin_addr.s_addr,
 446                                    0, 0,
 447                                    IPPROTO_GRE, RT_CONN_FLAGS(sk),
 448                                    sk->sk_bound_dev_if);
 449         if (IS_ERR(rt)) {
 450                 error = -EHOSTUNREACH;
 451                 goto end;
 452         }
 453         sk_setup_caps(sk, &rt->dst);
 454
 455         po->chan.mtu = dst_mtu(&rt->dst);
 456         if (!po->chan.mtu)
 457                 po->chan.mtu = PPP_MRU;
 458         po->chan.mtu -= PPTP_HEADER_OVERHEAD;
 459
 460         po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
 461         error = ppp_register_channel(&po->chan);
 462         if (error) {
 463                 pr_err("PPTP: failed to register PPP channel (%d)\n", error);
 464                 goto end;
 465         }
 466
 467         opt->dst_addr = sp->sa_addr.pptp;
 468         sk->sk_state |= PPPOX_CONNECTED;
 469
 470  end:
 471         release_sock(sk);
 472         return error;
 473 }
 474
 475 static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
 476         int peer)
 477 {
 478         int len = sizeof(struct sockaddr_pppox);
 479         struct sockaddr_pppox sp;
 480
 481         memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
 482
 483         sp.sa_family    = AF_PPPOX;
 484         sp.sa_protocol  = PX_PROTO_PPTP;
 485         sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
 486
 487         memcpy(uaddr, &sp, len);
 488
 489         return len;
 490 }
 491
 492 static int pptp_release(struct socket *sock)
 493 {
 494         struct sock *sk = sock->sk;
 495         struct pppox_sock *po;
 496         int error = 0;
 497
 498         if (!sk)
 499                 return 0;
 500
 501         lock_sock(sk);
 502
 503         if (sock_flag(sk, SOCK_DEAD)) {
 504                 release_sock(sk);
 505                 return -EBADF;
 506         }
 507
 508         po = pppox_sk(sk);
 509         del_chan(po);
 510         synchronize_rcu();
 511
 512         pppox_unbind_sock(sk);
 513         sk->sk_state = PPPOX_DEAD;
 514
 515         sock_orphan(sk);
 516         sock->sk = NULL;
 517
 518         release_sock(sk);
 519         sock_put(sk);
 520
 521         return error;
 522 }
 523
 524 static void pptp_sock_destruct(struct sock *sk)
 525 {
 526         if (!(sk->sk_state & PPPOX_DEAD)) {
 527                 del_chan(pppox_sk(sk));
 528                 pppox_unbind_sock(sk);
 529         }
 530         skb_queue_purge(&sk->sk_receive_queue);
 531         dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
 532 }
 533
 534 static int pptp_create(struct net *net, struct socket *sock, int kern)
 535 {
 536         int error = -ENOMEM;
 537         struct sock *sk;
 538         struct pppox_sock *po;
 539         struct pptp_opt *opt;
 540
 541         sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
 542         if (!sk)
 543                 goto out;
 544
 545         sock_init_data(sock, sk);
 546
 547         sock->state = SS_UNCONNECTED;
 548         sock->ops   = &pptp_ops;
 549
 550         sk->sk_backlog_rcv = pptp_rcv_core;
 551         sk->sk_state       = PPPOX_NONE;
 552         sk->sk_type        = SOCK_STREAM;
 553         sk->sk_family      = PF_PPPOX;
 554         sk->sk_protocol    = PX_PROTO_PPTP;
 555         sk->sk_destruct    = pptp_sock_destruct;
 556
 557         po = pppox_sk(sk);
 558         opt = &po->proto.pptp;
 559
 560         opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
 561         opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
 562
 563         error = 0;
 564 out:
 565         return error;
 566 }
 567
 568 static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
 569         unsigned long arg)
 570 {
 571         struct sock *sk = (struct sock *) chan->private;
 572         struct pppox_sock *po = pppox_sk(sk);
 573         struct pptp_opt *opt = &po->proto.pptp;
 574         void __user *argp = (void __user *)arg;
 575         int __user *p = argp;
 576         int err, val;
 577
 578         err = -EFAULT;
 579         switch (cmd) {
 580         case PPPIOCGFLAGS:
 581                 val = opt->ppp_flags;
 582                 if (put_user(val, p))
 583                         break;
 584                 err = 0;
 585                 break;
 586         case PPPIOCSFLAGS:
 587                 if (get_user(val, p))
 588                         break;
 589                 opt->ppp_flags = val & ~SC_RCV_BITS;
 590                 err = 0;
 591                 break;
 592         default:
 593                 err = -ENOTTY;
 594         }
 595
 596         return err;
 597 }
 598
 599 static const struct ppp_channel_ops pptp_chan_ops = {
 600         .start_xmit = pptp_xmit,
 601         .ioctl      = pptp_ppp_ioctl,
 602 };
 603
 604 static struct proto pptp_sk_proto __read_mostly = {
 605         .name     = "PPTP",
 606         .owner    = THIS_MODULE,
 607         .obj_size = sizeof(struct pppox_sock),
 608 };
 609
 610 static const struct proto_ops pptp_ops = {
 611         .family     = AF_PPPOX,
 612         .owner      = THIS_MODULE,
 613         .release    = pptp_release,
 614         .bind       = pptp_bind,
 615         .connect    = pptp_connect,
 616         .socketpair = sock_no_socketpair,
 617         .accept     = sock_no_accept,
 618         .getname    = pptp_getname,
 619         .listen     = sock_no_listen,
 620         .shutdown   = sock_no_shutdown,
 621         .setsockopt = sock_no_setsockopt,
 622         .getsockopt = sock_no_getsockopt,
 623         .sendmsg    = sock_no_sendmsg,
 624         .recvmsg    = sock_no_recvmsg,
 625         .mmap       = sock_no_mmap,
 626         .ioctl      = pppox_ioctl,
 627 #ifdef CONFIG_COMPAT
 628         .compat_ioctl = pppox_compat_ioctl,
 629 #endif
 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);