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         pppol2tp_fd_str = strdup(*argv);
 152         if (pppol2tp_fd_str == NULL)
 153                 novm("PPPoL2TP FD");
 154
 155         /* Setup option defaults. Compression options are disabled! */
 156
 157         modem = 0;
 158
 159         lcp_allowoptions[0].neg_accompression = 1;
 160         lcp_wantoptions[0].neg_accompression = 0;
 161
 162         lcp_allowoptions[0].neg_pcompression = 1;
 163         lcp_wantoptions[0].neg_pcompression = 0;
 164
 165         ccp_allowoptions[0].deflate = 0;
 166         ccp_wantoptions[0].deflate = 0;
 167
 168         ipcp_allowoptions[0].neg_vj = 0;
 169         ipcp_wantoptions[0].neg_vj = 0;
 170
 171         ccp_allowoptions[0].bsd_compress = 0;
 172         ccp_wantoptions[0].bsd_compress = 0;
 173
 174         the_channel = &pppol2tp_channel;
 175         device_got_set = 1;
 176
 177         return 1;
 178 }
 179
 180 static int connect_pppol2tp(void)
 181 {
 182         if(pppol2tp_fd == -1) {
 183                 fatal("No PPPoL2TP FD specified");
 184         }
 185
 186         return pppol2tp_fd;
 187 }
 188
 189 static void disconnect_pppol2tp(void)
 190 {
 191         if (pppol2tp_fd >= 0) {
 192                 close(pppol2tp_fd);
 193                 pppol2tp_fd = -1;
 194         }
 195 }
 196
 197 static void send_config_pppol2tp(int mtu,
 198                               u_int32_t asyncmap,
 199                               int pcomp,
 200                               int accomp)
 201 {
 202         struct ifreq ifr;
 203         int on = 1;
 204         int fd;
 205         char reorderto[16];
 206         char tid[8];
 207         char sid[8];
 208
 209         if (pppol2tp_ifname[0]) {
 210                 struct ifreq ifr;
 211                 int fd;
 212
 213                 fd = socket(AF_INET, SOCK_DGRAM, 0);
 214                 if (fd >= 0) {
 215                         memset (&ifr, '\0', sizeof (ifr));
 216                         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 217                         strlcpy(ifr.ifr_newname, pppol2tp_ifname,
 218                                 sizeof(ifr.ifr_name));
 219                         ioctl(fd, SIOCSIFNAME, (caddr_t) &ifr);
 220                         strlcpy(ifname, pppol2tp_ifname, 32);
 221                         if (pppol2tp_debug_mask & PPPOL2TP_MSG_CONTROL) {
 222                                 dbglog("ppp%d: interface name %s",
 223                                        ifunit, ifname);
 224                         }
 225                 }
 226                 close(fd);
 227         }
 228
 229         if ((lcp_allowoptions[0].mru > 0) && (mtu > lcp_allowoptions[0].mru)) {
 230                 warn("Overriding mtu %d to %d", mtu, lcp_allowoptions[0].mru);
 231                 mtu = lcp_allowoptions[0].mru;
 232         }
 233         netif_set_mtu(ifunit, mtu);
 234
 235         reorderto[0] = '\0';
 236         if (pppol2tp_reorder_timeout > 0)
 237                 sprintf(&reorderto[0], "%d ", pppol2tp_reorder_timeout);
 238         tid[0] = '\0';
 239         if (pppol2tp_tunnel_id > 0)
 240                 sprintf(&tid[0], "%hu ", pppol2tp_tunnel_id);
 241         sid[0] = '\0';
 242         if (pppol2tp_session_id > 0)
 243                 sprintf(&sid[0], "%hu ", pppol2tp_session_id);
 244
 245         dbglog("PPPoL2TP options: %s%s%s%s%s%s%s%s%sdebugmask %d",
 246                pppol2tp_recv_seq ? "recvseq " : "",
 247                pppol2tp_send_seq ? "sendseq " : "",
 248                pppol2tp_lns_mode ? "lnsmode " : "",
 249                pppol2tp_reorder_timeout ? "reorderto " : "", reorderto,
 250                pppol2tp_tunnel_id ? "tid " : "", tid,
 251                pppol2tp_session_id ? "sid " : "", sid,
 252                pppol2tp_debug_mask);
 253
 254         if (pppol2tp_recv_seq)
 255                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_RECVSEQ,
 256                                &on, sizeof(on)) < 0)
 257                         fatal("setsockopt(PPPOL2TP_RECVSEQ): %m");
 258         if (pppol2tp_send_seq)
 259                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_SENDSEQ,
 260                                &on, sizeof(on)) < 0)
 261                         fatal("setsockopt(PPPOL2TP_SENDSEQ): %m");
 262         if (pppol2tp_lns_mode)
 263                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_LNSMODE,
 264                                &on, sizeof(on)) < 0)
 265                         fatal("setsockopt(PPPOL2TP_LNSMODE): %m");
 266         if (pppol2tp_reorder_timeout)
 267                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_REORDERTO,
 268                                &pppol2tp_reorder_timeout,
 269                                sizeof(pppol2tp_reorder_timeout)) < 0)
 270                         fatal("setsockopt(PPPOL2TP_REORDERTO): %m");
 271         if (pppol2tp_debug_mask)
 272                 if (setsockopt(pppol2tp_fd, SOL_PPPOL2TP, PPPOL2TP_SO_DEBUG,
 273                                &pppol2tp_debug_mask, sizeof(pppol2tp_debug_mask)) < 0)
 274                         fatal("setsockopt(PPPOL2TP_DEBUG): %m");
 275 }
 276
 277 static void recv_config_pppol2tp(int mru,
 278                               u_int32_t asyncmap,
 279                               int pcomp,
 280                               int accomp)
 281 {
 282         if ((lcp_allowoptions[0].mru > 0) && (mru > lcp_allowoptions[0].mru)) {
 283                 warn("Overriding mru %d to mtu value %d", mru,
 284                      lcp_allowoptions[0].mru);
 285                 mru = lcp_allowoptions[0].mru;
 286         }
 287         if ((ifunit >= 0) && ioctl(pppol2tp_fd, PPPIOCSMRU, (caddr_t) &mru) < 0)
 288                 error("Couldn't set PPP MRU: %m");
 289 }
 290
 291 /*****************************************************************************
 292  * Snoop LCP message exchanges to capture negotiated ACCM values.
 293  * When asyncmap values have been seen from both sides, give the values to
 294  * L2TP.
 295  * This code is derived from Roaring Penguin L2TP.
 296  *****************************************************************************/
 297
 298 static void pppol2tp_lcp_snoop(unsigned char *buf, int len, int incoming)
 299 {
 300         static bool got_send_accm = 0;
 301         static bool got_recv_accm = 0;
 302         static uint32_t recv_accm = 0xffffffff;
 303         static uint32_t send_accm = 0xffffffff;
 304         static bool snooping = 1;
 305
 306         uint16_t protocol;
 307         uint16_t lcp_pkt_len;
 308         int opt, opt_len;
 309         int reject;
 310         unsigned char const *opt_data;
 311         uint32_t accm;
 312
 313         /* Skip HDLC header */
 314         buf += 2;
 315         len -= 2;
 316
 317         /* Unreasonably short frame?? */
 318         if (len <= 0) return;
 319
 320         /* Get protocol */
 321         if (buf[0] & 0x01) {
 322                 /* Compressed protcol field */
 323                 protocol = buf[0];
 324         } else {
 325                 protocol = ((unsigned int) buf[0]) * 256 + buf[1];
 326         }
 327
 328         /* If it's a network protocol, stop snooping */
 329         if (protocol <= 0x3fff) {
 330                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DEBUG) {
 331                         dbglog("Turning off snooping: "
 332                                "Network protocol %04x found.",
 333                                protocol);
 334                 }
 335                 snooping = 0;
 336                 return;
 337         }
 338
 339         /* If it's not LCP, do not snoop */
 340         if (protocol != 0xc021) {
 341                 return;
 342         }
 343
 344         /* Skip protocol; go to packet data */
 345         buf += 2;
 346         len -= 2;
 347
 348         /* Unreasonably short frame?? */
 349         if (len <= 0) return;
 350
 351         /* Look for Configure-Ack or Configure-Reject code */
 352         if (buf[0] != CONFACK && buf[0] != CONFREJ) return;
 353
 354         reject = (buf[0] == CONFREJ);
 355
 356         lcp_pkt_len = ((unsigned int) buf[2]) * 256 + buf[3];
 357
 358         /* Something fishy with length field? */
 359         if (lcp_pkt_len > len) return;
 360
 361         /* Skip to options */
 362         len = lcp_pkt_len - 4;
 363         buf += 4;
 364
 365         while (len > 0) {
 366                 /* Pull off an option */
 367                 opt = buf[0];
 368                 opt_len = buf[1];
 369                 opt_data = &buf[2];
 370                 if (opt_len > len || opt_len < 2) break;
 371                 len -= opt_len;
 372                 buf += opt_len;
 373                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DEBUG) {
 374                         dbglog("Found option type %02x; len %d", opt, opt_len);
 375                 }
 376
 377                 /* We are specifically interested in ACCM */
 378                 if (opt == CI_ASYNCMAP && opt_len == 0x06) {
 379                         if (reject) {
 380                                 /* ACCM negotiation REJECTED; use default */
 381                                 accm = 0xffffffff;
 382                                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DATA) {
 383                                         dbglog("Rejected ACCM negotiation; "
 384                                                "defaulting (%s)",
 385                                                incoming ? "incoming" : "outgoing");
 386                                 }
 387                                 recv_accm = accm;
 388                                 send_accm = accm;
 389                                 got_recv_accm = 1;
 390                                 got_send_accm = 1;
 391                         } else {
 392                                 memcpy(&accm, opt_data, sizeof(accm));
 393                                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_DATA) {
 394                                         dbglog("Found ACCM of %08x (%s)", accm,
 395                                                incoming ? "incoming" : "outgoing");
 396                                 }
 397                                 if (incoming) {
 398                                         recv_accm = accm;
 399                                         got_recv_accm = 1;
 400                                 } else {
 401                                         send_accm = accm;
 402                                         got_send_accm = 1;
 403                                 }
 404                         }
 405
 406                         if (got_recv_accm && got_send_accm) {
 407                                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_CONTROL) {
 408                                         dbglog("Telling L2TP: Send ACCM = %08x; "
 409                                                "Receive ACCM = %08x", send_accm, recv_accm);
 410                                 }
 411                                 if (pppol2tp_send_accm_hook != NULL) {
 412                                         (*pppol2tp_send_accm_hook)(pppol2tp_tunnel_id,
 413                                                                    pppol2tp_session_id,
 414                                                                    send_accm, recv_accm);
 415                                 }
 416                                 got_recv_accm = 0;
 417                                 got_send_accm = 0;
 418                         }
 419                 }
 420         }
 421 }
 422
 423 static void pppol2tp_lcp_snoop_recv(unsigned char *p, int len)
 424 {
 425         if (old_snoop_recv_hook != NULL)
 426                 (*old_snoop_recv_hook)(p, len);
 427         pppol2tp_lcp_snoop(p, len, 1);
 428 }
 429
 430 static void pppol2tp_lcp_snoop_send(unsigned char *p, int len)
 431 {
 432         if (old_snoop_send_hook != NULL)
 433                 (*old_snoop_send_hook)(p, len);
 434         pppol2tp_lcp_snoop(p, len, 0);
 435 }
 436
 437 /*****************************************************************************
 438  * Interface up/down events
 439  *****************************************************************************/
 440
 441 static void pppol2tp_ip_up(void *opaque, int arg)
 442 {
 443         /* may get called twice (for IPv4 and IPv6) but the hook handles that well */
 444         if (pppol2tp_ip_updown_hook != NULL) {
 445                 (*pppol2tp_ip_updown_hook)(pppol2tp_tunnel_id,
 446                                            pppol2tp_session_id, 1);
 447         }
 448 }
 449
 450 static void pppol2tp_ip_down(void *opaque, int arg)
 451 {
 452         /* may get called twice (for IPv4 and IPv6) but the hook handles that well */
 453         if (pppol2tp_ip_updown_hook != NULL) {
 454                 (*pppol2tp_ip_updown_hook)(pppol2tp_tunnel_id,
 455                                            pppol2tp_session_id, 0);
 456         }
 457 }
 458
 459 /*****************************************************************************
 460  * Application init
 461  *****************************************************************************/
 462
 463 static void pppol2tp_check_options(void)
 464 {
 465         /* Enable LCP snooping for ACCM options only for LNS */
 466         if (pppol2tp_lns_mode) {
 467                 if ((pppol2tp_tunnel_id == 0) || (pppol2tp_session_id == 0)) {
 468                         fatal("tunnel_id/session_id values not specified");
 469                 }
 470                 if (pppol2tp_debug_mask & PPPOL2TP_MSG_CONTROL) {
 471                         dbglog("Enabling LCP snooping");
 472                 }
 473                 old_snoop_recv_hook = snoop_recv_hook;
 474                 old_snoop_send_hook = snoop_send_hook;
 475
 476                 snoop_recv_hook = pppol2tp_lcp_snoop_recv;
 477                 snoop_send_hook = pppol2tp_lcp_snoop_send;
 478         }
 479 }
 480
 481 /* Called just before pppd exits.
 482  */
 483 static void pppol2tp_cleanup(void)
 484 {
 485         if (pppol2tp_debug_mask & PPPOL2TP_MSG_DEBUG) {
 486                 dbglog("pppol2tp: exiting.");
 487         }
 488         disconnect_pppol2tp();
 489 }
 490
 491 void plugin_init(void)
 492 {
 493 #if defined(__linux__)
 494         extern int new_style_driver;    /* From sys-linux.c */
 495         if (!ppp_available() && !new_style_driver)
 496                 fatal("Kernel doesn't support ppp_generic - "
 497                     "needed for PPPoL2TP");
 498 #else
 499         fatal("No PPPoL2TP support on this OS");
 500 #endif
 501         add_options(pppol2tp_options);
 502
 503         /* Hook up ip up/down notifiers to send indicator to openl2tpd
 504          * that the link is up
 505          */
 506         add_notifier(&ip_up_notifier, pppol2tp_ip_up, NULL);
 507         add_notifier(&ip_down_notifier, pppol2tp_ip_down, NULL);
 508         add_notifier(&ipv6_up_notifier, pppol2tp_ip_up, NULL);
 509         add_notifier(&ipv6_down_notifier, pppol2tp_ip_down, NULL);
 510 }
 511
 512 struct channel pppol2tp_channel = {
 513     options: pppol2tp_options,
 514     process_extra_options: NULL,
 515     check_options: &pppol2tp_check_options,
 516     connect: &connect_pppol2tp,
 517     disconnect: &disconnect_pppol2tp,
 518     establish_ppp: &generic_establish_ppp,
 519     disestablish_ppp: &generic_disestablish_ppp,
 520     send_config: &send_config_pppol2tp,
 521     recv_config: &recv_config_pppol2tp,
 522     close: NULL,
 523     cleanup: NULL
 524 };