pppd/plugins/pppol2tp/pppol2tp.c

   1 /* pppol2tp.c - pppd plugin to implement PPPoL2TP protocol
   2  *   for Linux using kernel pppol2tp support.
   3  *
   4  * Requires kernel pppol2tp driver which is integrated into the kernel
   5  * from 2.6.23 onwards. For earlier kernels, a version can be obtained
   6  * from the OpenL2TP project at
   7  * http://www.sourceforge.net/projects/openl2tp/
   8  *
   9  * Original by Martijn van Oosterhout <kleptog@svana.org>
  10  * Modified by jchapman@katalix.com
  11  *
  12  * Heavily based upon pppoatm.c: original notice follows
  13  *
  14  * Copyright 2000 Mitchell Blank Jr.
  15  * Based in part on work from Jens Axboe and Paul Mackerras.
  16  * Updated to ppp-2.4.1 by Bernhard Kaindl
  17  *
  18  *  This program is free software; you can redistribute it and/or
  19  *  modify it under the terms of the GNU General Public License
  20  *  as published by the Free Software Foundation; either version
  21  *  2 of the License, or (at your option) any later version.
  22  */
  23 #include <unistd.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <errno.h>
  27 #include "pppd.h"
  28 #include "pathnames.h"
  29 #include "fsm.h"
  30 #include "lcp.h"
  31 #include "ccp.h"
  32 #include "ipcp.h"
  33 #include <sys/stat.h>
  34 #include <net/if.h>
  35 #include <sys/ioctl.h>
  36 #include <sys/socket.h>
  37 #include <netinet/in.h>
  38 #include <signal.h>
  39 #include <linux/version.h>
  40 #include <linux/sockios.h>
  41 #ifndef aligned_u64
  42 /* should be defined in sys/types.h */
  43 #define aligned_u64 unsigned long long __attribute__((aligned(8)))
  44 #endif
  45 #include <linux/types.h>
  46 #include <linux/if_ether.h>
  47 #include <linux/ppp_defs.h>
  48 #include <linux/if_ppp.h>
  49 #include <linux/if_pppox.h>
  50 #include <linux/if_pppol2tp.h>
  51
  52 /* should be added to system's socket.h... */
  53 #ifndef SOL_PPPOL2TP
  54 #define SOL_PPPOL2TP    273
  55 #endif
  56
  57 const char pppd_version[] = VERSION;
  58
  59 static int setdevname_pppol2tp(char **argv);
  60
  61 static int pppol2tp_fd = -1;
  62 static char *pppol2tp_fd_str;
  63 static bool pppol2tp_lns_mode = 0;
  64 static bool pppol2tp_recv_seq = 0;
  65 static bool pppol2tp_send_seq = 0;
  66 static int pppol2tp_debug_mask = 0;
  67 static int pppol2tp_reorder_timeout = 0;
  68 static char pppol2tp_ifname[32] = { 0, };
  69 int pppol2tp_tunnel_id = 0;
  70 int pppol2tp_session_id = 0;
  71
  72 static int device_got_set = 0;
  73 struct channel pppol2tp_channel;
  74
  75 static void (*old_snoop_recv_hook)(unsigned char *p, int len) = NULL;
  76 static void (*old_snoop_send_hook)(unsigned char *p, int len) = NULL;
  77
  78 /* Hook provided to allow other plugins to handle ACCM changes */
  79 void (*pppol2tp_send_accm_hook)(int tunnel_id, int session_id,
  80                                 uint32_t send_accm, uint32_t recv_accm) = NULL;
  81
  82 /* Hook provided to allow other plugins to handle IP up/down */
  83 void (*pppol2tp_ip_updown_hook)(int tunnel_id, int session_id, int up) = NULL;
  84
  85 static option_t pppol2tp_options[] = {
  86         { "pppol2tp", o_special, &setdevname_pppol2tp,
  87           "FD for PPPoL2TP socket", OPT_DEVNAM | OPT_A2STRVAL,
  88           &pppol2tp_fd_str },
  89         { "pppol2tp_lns_mode", o_bool, &pppol2tp_lns_mode,
  90           "PPPoL2TP LNS behavior. Default off.",
  91           OPT_PRIO | OPRIO_CFGFILE },
  92         { "pppol2tp_send_seq", o_bool, &pppol2tp_send_seq,
  93           "PPPoL2TP enable sequence numbers in transmitted data packets. "
  94           "Default off.",
  95           OPT_PRIO | OPRIO_CFGFILE },
  96         { "pppol2tp_recv_seq", o_bool, &pppol2tp_recv_seq,
  97           "PPPoL2TP enforce sequence numbers in received data packets. "
  98           "Default off.",
  99           OPT_PRIO | OPRIO_CFGFILE },
 100         { "pppol2tp_reorderto", o_int, &pppol2tp_reorder_timeout,
 101           "PPPoL2TP data packet reorder timeout. Default 0 (no reordering).",
 102           OPT_PRIO },
 103         { "pppol2tp_debug_mask", o_int, &pppol2tp_debug_mask,
 104           "PPPoL2TP debug mask. Default: no debug.",
 105           OPT_PRIO },
 106         { "pppol2tp_ifname", o_string, &pppol2tp_ifname,
 107           "Set interface name of PPP interface",
 108           OPT_PRIO | OPT_PRIV | OPT_STATIC, NULL, 16 },
 109         { "pppol2tp_tunnel_id", o_int, &pppol2tp_tunnel_id,
 110           "PPPoL2TP tunnel_id.",
 111           OPT_PRIO },
 112         { "pppol2tp_session_id", o_int, &pppol2tp_session_id,
 113           "PPPoL2TP session_id.",
 114           OPT_PRIO },
 115         { NULL }
 116 };
 117
 118 static int setdevname_pppol2tp(char **argv)
 119 {
 120         union {
 121                 char buffer[128];
 122                 struct sockaddr pppol2tp;
 123         } s;
 124         int len = sizeof(s);
 125         char **a;
 126         int tmp;
 127         int tmp_len = sizeof(tmp);
 128
 129         if (device_got_set)
 130                 return 0;
 131
 132         if (!int_option(*argv, &pppol2tp_fd))
 133                 return 0;
 134
 135         if(getsockname(pppol2tp_fd, (struct sockaddr *)&s, &len) < 0) {
 136                 fatal("Given FD for PPPoL2TP socket invalid (%s)",
 137                       strerror(errno));
 138         }
 139         if(s.pppol2tp.sa_family != AF_PPPOX) {
 140                 fatal("Socket of not a PPPoX socket");
 141         }
 142
 143         /* Do a test getsockopt() to ensure that the kernel has the necessary
 144          * feature available.
 145          */
 146         if (getsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_DEBUG,
 147                        &tmp, &tmp_len) < 0) {
 148                 fatal("PPPoL2TP kernel driver not installed");
 149         }
 150
 151         /* Setup option defaults. Compression options are disabled! */
 152
 153         modem = 0;
 154
 155         lcp_allowoptions[0].neg_accompression = 1;
 156         lcp_wantoptions[0].neg_accompression = 0;
 157
 158         lcp_allowoptions[0].neg_pcompression = 1;
 159         lcp_wantoptions[0].neg_pcompression = 0;
 160
 161         ccp_allowoptions[0].deflate = 0;
 162         ccp_wantoptions[0].deflate = 0;
 163
 164         ipcp_allowoptions[0].neg_vj = 0;
 165         ipcp_wantoptions[0].neg_vj = 0;
 166
 167         ccp_allowoptions[0].bsd_compress = 0;
 168         ccp_wantoptions[0].bsd_compress = 0;
 169
 170         the_channel = &pppol2tp_channel;
 171         device_got_set = 1;
 172
 173         return 1;
 174 }
 175
 176 static int connect_pppol2tp(void)
 177 {
 178         if(pppol2tp_fd == -1) {
 179                 fatal("No PPPoL2TP FD specified");
 180         }
 181
 182         return pppol2tp_fd;
 183 }
 184
 185 static void disconnect_pppol2tp(void)
 186 {
 187         if (pppol2tp_fd >= 0) {
 188                 close(pppol2tp_fd);
 189                 pppol2tp_fd = -1;
 190         }
 191 }
 192
 193 static void send_config_pppol2tp(int mtu,
 194                               u_int32_t asyncmap,
 195                               int pcomp,
 196                               int accomp)
 197 {
 198         struct ifreq ifr;
 199         int on = 1;
 200         int fd;
 201         char reorderto[16];
 202         char tid[8];
 203         char sid[8];
 204
 205         if (pppol2tp_ifname[0]) {
 206                 struct ifreq ifr;
 207                 int fd;
 208
 209                 fd = socket(AF_INET, SOCK_DGRAM, 0);
 210                 if (fd >= 0) {
 211                         memset (&ifr, '\0', sizeof (ifr));
 212                         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 213                         strlcpy(ifr.ifr_newname, pppol2tp_ifname,
 214                                 sizeof(ifr.ifr_name));
 215                         ioctl(fd, SIOCSIFNAME, (caddr_t) &ifr);
 216                         strlcpy(ifname, pppol2tp_ifname, 32);
 217                         if (pppol2tp_debug_mask & PPPOL2TP_MSG_CONTROL) {
 218                                 dbglog("ppp%d: interface name %s",
 219                                        ifunit, ifname);
 220                         }
 221                 }
 222                 close(fd);
 223         }
 224
 225         if ((lcp_allowoptions[0].mru > 0) && (mtu > lcp_allowoptions[0].mru)) {
 226                 warn("Overriding mtu %d to %d", mtu, lcp_allowoptions[0].mru);
 227                 mtu = lcp_allowoptions[0].mru;
 228         }
 229         netif_set_mtu(ifunit, mtu);
 230
 231         reorderto[0] = '\0';
 232         if (pppol2tp_reorder_timeout > 0)
 233                 sprintf(&reorderto[0], "%d ", pppol2tp_reorder_timeout);
 234         tid[0] = '\0';
 235         if (pppol2tp_tunnel_id > 0)
 236                 sprintf(&tid[0], "%hu ", pppol2tp_tunnel_id);
 237         sid[0] = '\0';
 238         if (pppol2tp_session_id > 0)
 239                 sprintf(&sid[0], "%hu ", pppol2tp_session_id);
 240
 241         dbglog("PPPoL2TP options: %s%s%s%s%s%s%s%s%sdebugmask %d",
 242                pppol2tp_recv_seq ? "recvseq " : "",
 243                pppol2tp_send_seq ? "sendseq " : "",
 244                pppol2tp_lns_mode ? "lnsmode " : "",
 245                pppol2tp_reorder_timeout ? "reorderto " : "", reorderto,
 246                pppol2tp_tunnel_id ? "tid " : "", tid,
 247                pppol2tp_session_id ? "sid " : "", sid,
 248                pppol2tp_debug_mask);
 249
 250         if (pppol2tp_recv_seq)
 251                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_RECVSEQ,
 252                                &on, sizeof(on)) < 0)
 253                         fatal("setsockopt(PPPOL2TP_RECVSEQ): %m");
 254         if (pppol2tp_send_seq)
 255                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_SENDSEQ,
 256                                &on, sizeof(on)) < 0)
 257                         fatal("setsockopt(PPPOL2TP_SENDSEQ): %m");
 258         if (pppol2tp_lns_mode)
 259                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_LNSMODE,
 260                                &on, sizeof(on)) < 0)
 261                         fatal("setsockopt(PPPOL2TP_LNSMODE): %m");
 262         if (pppol2tp_reorder_timeout)
 263                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_REORDERTO,
 264                                &pppol2tp_reorder_timeout,
 265                                sizeof(pppol2tp_reorder_timeout)) < 0)
 266                         fatal("setsockopt(PPPOL2TP_REORDERTO): %m");
 267         if (pppol2tp_debug_mask)
 268                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_DEBUG,
 269                                &pppol2tp_debug_mask, sizeof(pppol2tp_debug_mask)) < 0)
 270                         fatal("setsockopt(PPPOL2TP_DEBUG): %m");
 271 }
 272
 273 static void recv_config_pppol2tp(int mru,
 274                               u_int32_t asyncmap,
 275                               int pcomp,
 276                               int accomp)
 277 {
 278         if ((lcp_allowoptions[0].mru > 0) && (mru > lcp_allowoptions[0].mru)) {
 279                 warn("Overriding mru %d to mtu value %d", mru,
 280                      lcp_allowoptions[0].mru);
 281                 mru = lcp_allowoptions[0].mru;
 282         }
 283         if ((ifunit >= 0) && ioctl(pppol2tp_fd, PPPIOCSMRU, (caddr_t) &mru) < 0)
 284                 error("Couldn't set PPP MRU: %m");
 285 }
 286
 287 /*****************************************************************************
 288  * Snoop LCP message exchanges to capture negotiated ACCM values.
 289  * When asyncmap values have been seen from both sides, give the values to
 290  * L2TP.
 291  * This code is derived from Roaring Penguin L2TP.
 292  *****************************************************************************/
 293
 294 static void pppol2tp_lcp_snoop(unsigned char *buf, int len, int incoming)
 295 {
 296         static bool got_send_accm = 0;
 297         static bool got_recv_accm = 0;
 298         static uint32_t recv_accm = 0xffffffff;
 299         static uint32_t send_accm = 0xffffffff;
 300         static bool snooping = 1;
 301
 302         uint16_t protocol;
 303         uint16_t lcp_pkt_len;
 304         int opt, opt_len;
 305         int reject;
 306         unsigned char const *opt_data;
 307         uint32_t accm;
 308
 309         /* Skip HDLC header */
 310         buf += 2;
 311         len -= 2;
 312
 313         /* Unreasonably short frame?? */
 314         if (len <= 0) return;
 315
 316         /* Get protocol */
 317         if (buf[0] & 0x01) {
 318                 /* Compressed protcol field */
 319                 protocol = buf[0];
 320         } else {
 321                 protocol = ((unsigned int) buf[0]) * 256 + buf[1];
 322         }
 323
 324         /* If it's a network protocol, stop snooping */
 325         if (protocol <= 0x3fff) {
 326                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DEBUG) {
 327                         dbglog("Turning off snooping: "
 328                                "Network protocol %04x found.",
 329                                protocol);
 330                 }
 331                 snooping = 0;
 332                 return;
 333         }
 334
 335         /* If it's not LCP, do not snoop */
 336         if (protocol != 0xc021) {
 337                 return;
 338         }
 339
 340         /* Skip protocol; go to packet data */
 341         buf += 2;
 342         len -= 2;
 343
 344         /* Unreasonably short frame?? */
 345         if (len <= 0) return;
 346
 347         /* Look for Configure-Ack or Configure-Reject code */
 348         if (buf[0] != CONFACK && buf[0] != CONFREJ) return;
 349
 350         reject = (buf[0] == CONFREJ);
 351
 352         lcp_pkt_len = ((unsigned int) buf[2]) * 256 + buf[3];
 353
 354         /* Something fishy with length field? */
 355         if (lcp_pkt_len > len) return;
 356
 357         /* Skip to options */
 358         len = lcp_pkt_len - 4;
 359         buf += 4;
 360
 361         while (len > 0) {
 362                 /* Pull off an option */
 363                 opt = buf[0];
 364                 opt_len = buf[1];
 365                 opt_data = &buf[2];
 366                 if (opt_len > len || opt_len < 2) break;
 367                 len -= opt_len;
 368                 buf += opt_len;
 369                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DEBUG) {
 370                         dbglog("Found option type %02x; len %d", opt, opt_len);
 371                 }
 372
 373                 /* We are specifically interested in ACCM */
 374                 if (opt == CI_ASYNCMAP && opt_len == 0x06) {
 375                         if (reject) {
 376                                 /* ACCM negotiation REJECTED; use default */
 377                                 accm = 0xffffffff;
 378                                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DATA) {
 379                                         dbglog("Rejected ACCM negotiation; "
 380                                                "defaulting (%s)",
 381                                                incoming ? "incoming" : "outgoing");
 382                                 }
 383                                 recv_accm = accm;
 384                                 send_accm = accm;
 385                                 got_recv_accm = 1;
 386                                 got_send_accm = 1;
 387                         } else {
 388                                 memcpy(&accm, opt_data, sizeof(accm));
 389                                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DATA) {
 390                                         dbglog("Found ACCM of %08x (%s)", accm,
 391                                                incoming ? "incoming" : "outgoing");
 392                                 }
 393                                 if (incoming) {
 394                                         recv_accm = accm;
 395                                         got_recv_accm = 1;
 396                                 } else {
 397                                         send_accm = accm;
 398                                         got_send_accm = 1;
 399                                 }
 400                         }
 401
 402                         if (got_recv_accm && got_send_accm) {
 403                                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_CONTROL) {
 404                                         dbglog("Telling L2TP: Send ACCM = %08x; "
 405                                                "Receive ACCM = %08x", send_accm, recv_accm);
 406                                 }
 407                                 if (pppol2tp_send_accm_hook != NULL) {
 408                                         (*pppol2tp_send_accm_hook)(pppol2tp_tunnel_id,
 409                                                                    pppol2tp_session_id,
 410                                                                    send_accm, recv_accm);
 411                                 }
 412                                 got_recv_accm = 0;
 413                                 got_send_accm = 0;
 414                         }
 415                 }
 416         }
 417 }
 418
 419 static void pppol2tp_lcp_snoop_recv(unsigned char *p, int len)
 420 {
 421         if (old_snoop_recv_hook != NULL)
 422                 (*old_snoop_recv_hook)(p, len);
 423         pppol2tp_lcp_snoop(p, len, 1);
 424 }
 425
 426 static void pppol2tp_lcp_snoop_send(unsigned char *p, int len)
 427 {
 428         if (old_snoop_send_hook != NULL)
 429                 (*old_snoop_send_hook)(p, len);
 430         pppol2tp_lcp_snoop(p, len, 0);
 431 }
 432
 433 /*****************************************************************************
 434  * Interface up/down events
 435  *****************************************************************************/
 436
 437 static void pppol2tp_ip_up(void *opaque, int arg)
 438 {
 439         /* may get called twice (for IPv4 and IPv6) but the hook handles that well */
 440         if (pppol2tp_ip_updown_hook != NULL) {
 441                 (*pppol2tp_ip_updown_hook)(pppol2tp_tunnel_id,
 442                                            pppol2tp_session_id, 1);
 443         }
 444 }
 445
 446 static void pppol2tp_ip_down(void *opaque, int arg)
 447 {
 448         /* may get called twice (for IPv4 and IPv6) but the hook handles that well */
 449         if (pppol2tp_ip_updown_hook != NULL) {
 450                 (*pppol2tp_ip_updown_hook)(pppol2tp_tunnel_id,
 451                                            pppol2tp_session_id, 0);
 452         }
 453 }
 454
 455 /*****************************************************************************
 456  * Application init
 457  *****************************************************************************/
 458
 459 static void pppol2tp_check_options(void)
 460 {
 461         /* Enable LCP snooping for ACCM options only for LNS */
 462         if (pppol2tp_lns_mode) {
 463                 if ((pppol2tp_tunnel_id == 0) || (pppol2tp_session_id == 0)) {
 464                         fatal("tunnel_id/session_id values not specified");
 465                 }
 466                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_CONTROL) {
 467                         dbglog("Enabling LCP snooping");
 468                 }
 469                 old_snoop_recv_hook = snoop_recv_hook;
 470                 old_snoop_send_hook = snoop_send_hook;
 471
 472                 snoop_recv_hook = pppol2tp_lcp_snoop_recv;
 473                 snoop_send_hook = pppol2tp_lcp_snoop_send;
 474         }
 475 }
 476
 477 /* Called just before pppd exits.
 478  */
 479 static void pppol2tp_cleanup(void)
 480 {
 481         if (pppol2tp_debug_mask & PPPOL2TP_MSG_DEBUG) {
 482                 dbglog("pppol2tp: exiting.");
 483         }
 484         disconnect_pppol2tp();
 485 }
 486
 487 void plugin_init(void)
 488 {
 489 #if defined(__linux__)
 490         extern int new_style_driver;    /* From sys-linux.c */
 491         if (!ppp_available() && !new_style_driver)
 492                 fatal("Kernel doesn't support ppp_generic - "
 493                     "needed for PPPoL2TP");
 494 #else
 495         fatal("No PPPoL2TP support on this OS");
 496 #endif
 497         add_options(pppol2tp_options);
 498
 499         /* Hook up ip up/down notifiers to send indicator to openl2tpd
 500          * that the link is up
 501          */
 502         add_notifier(&ip_up_notifier, pppol2tp_ip_up, NULL);
 503         add_notifier(&ip_down_notifier, pppol2tp_ip_down, NULL);
 504         add_notifier(&ipv6_up_notifier, pppol2tp_ip_up, NULL);
 505         add_notifier(&ipv6_down_notifier, pppol2tp_ip_down, NULL);
 506 }
 507
 508 struct channel pppol2tp_channel = {
 509     options: pppol2tp_options,
 510     process_extra_options: NULL,
 511     check_options: &pppol2tp_check_options,
 512     connect: &connect_pppol2tp,
 513     disconnect: &disconnect_pppol2tp,
 514     establish_ppp: &generic_establish_ppp,
 515     disestablish_ppp: &generic_disestablish_ppp,
 516     send_config: &send_config_pppol2tp,
 517     recv_config: &recv_config_pppol2tp,
 518     close: NULL,
 519     cleanup: NULL
 520 };