tun.c

   1 /*
   2  * OpenConnect (SSL + DTLS) VPN client
   3  *
   4  * Copyright © 2008 Intel Corporation.
   5  *
   6  * Author: David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * version 2.1, as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to:
  19  *
  20  *   Free Software Foundation, Inc.
  21  *   51 Franklin Street, Fifth Floor,
  22  *   Boston, MA 02110-1301 USA
  23  */
  24
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <sys/socket.h>
  28 #include <sys/ioctl.h>
  29 #include <string.h>
  30 #include <signal.h>
  31 #include <fcntl.h>
  32 #include <unistd.h>
  33 #include <netdb.h>
  34 #include <netinet/in_systm.h>
  35 #include <netinet/in.h>
  36 #include <netinet/ip.h>
  37 #include <net/if.h>
  38 #include <arpa/inet.h>
  39 #include <errno.h>
  40 #if defined(__sun__)
  41 #include <net/if_tun.h>
  42 #include <stropts.h>
  43 #include <sys/sockio.h>
  44 #endif
  45
  46 #include "openconnect.h"
  47
  48 /*
  49  * If an if_tun.h include file was found anywhere (by the Makefile), it's
  50  * included. Else, we end up assuming that we have BSD-style devices such
  51  * as /dev/tun0 etc.
  52  */
  53 #ifdef IF_TUN_HDR
  54 #include IF_TUN_HDR
  55 #endif
  56
  57 /*
  58  * The OS X tun/tap driver doesn't provide a header file; you're expected
  59  * to define this for yourself.
  60  */
  61 #ifdef __APPLE__
  62 #define TUNSIFHEAD  _IOW('t', 96, int)
  63 #endif
  64
  65 /*
  66  * OpenBSD always puts the protocol family prefix onto packets. Other
  67  * systems let us enable that with the TUNSIFHEAD ioctl, and some of them
  68  * (e.g. FreeBSD) _need_ it otherwise they'll interpret IPv6 packets as IPv4.
  69  */
  70 #if defined(__OpenBSD__) || defined(TUNSIFHEAD)
  71 #define TUN_HAS_AF_PREFIX 1
  72 #endif
  73
  74 #ifdef __sun__
  75 static int local_config_tun(struct openconnect_info *vpninfo, int mtu_only)
  76 {
  77         if (!mtu_only)
  78                 vpninfo->progress(vpninfo, PRG_ERR,
  79                                   "No vpnc-script configured. Need Solaris IP-setting code\n");
  80         return 0;
  81 }
  82 #else
  83 static int local_config_tun(struct openconnect_info *vpninfo, int mtu_only)
  84 {
  85         struct ifreq ifr;
  86         int net_fd;
  87
  88         net_fd = socket(PF_INET, SOCK_DGRAM, 0);
  89         if (net_fd < 0) {
  90                 perror("open net");
  91                 return -EINVAL;
  92         }
  93         memset(&ifr, 0, sizeof(ifr));
  94         strncpy(ifr.ifr_name, vpninfo->ifname, sizeof(ifr.ifr_name) - 1);
  95
  96         if (!mtu_only) {
  97                 struct sockaddr_in addr;
  98
  99                 if (ioctl(net_fd, SIOCGIFFLAGS, &ifr) < 0)
 100                         perror("SIOCGIFFLAGS");
 101
 102                 ifr.ifr_flags |= IFF_UP | IFF_POINTOPOINT;
 103                 if (ioctl(net_fd, SIOCSIFFLAGS, &ifr) < 0)
 104                         perror("SIOCSIFFLAGS");
 105
 106                 addr.sin_family = AF_INET;
 107                 addr.sin_addr.s_addr = inet_addr(vpninfo->vpn_addr);
 108                 memcpy(&ifr.ifr_addr, &addr, sizeof(addr));
 109                 if (ioctl(net_fd, SIOCSIFADDR, &ifr) < 0)
 110                         perror("SIOCSIFADDR");
 111         }
 112
 113         ifr.ifr_mtu = vpninfo->mtu;
 114         if (ioctl(net_fd, SIOCSIFMTU, &ifr) < 0)
 115                 perror("SIOCSIFMTU");
 116
 117         close(net_fd);
 118
 119         return 0;
 120 }
 121 #endif
 122
 123 static int setenv_int(const char *opt, int value)
 124 {
 125         char buf[16];
 126         sprintf(buf, "%d", value);
 127         return setenv(opt, buf, 1);
 128 }
 129
 130 static int netmasklen(struct in_addr addr)
 131 {
 132         int masklen;
 133
 134         for (masklen = 0; masklen < 32; masklen++) {
 135                 if (ntohl(addr.s_addr) >= (0xffffffff << masklen))
 136                         break;
 137         }
 138         return 32 - masklen;
 139 }
 140
 141 static int process_split_xxclude(struct openconnect_info *vpninfo,
 142                                  char *in_ex, char *route, int *v4_incs,
 143                                  int *v6_incs)
 144 {
 145         struct in_addr addr;
 146         char envname[80];
 147         char *slash;
 148
 149         slash = strchr(route, '/');
 150         if (!slash) {
 151         badinc:
 152                 vpninfo->progress(vpninfo, PRG_ERR,
 153                                   "Discard bad split %sclude: \"%s\"\n",
 154                                   in_ex, route);
 155                 return -EINVAL;
 156         }
 157
 158         *slash = 0;
 159
 160         if (strchr(route, ':')) {
 161                 snprintf(envname, 79, "CISCO_IPV6_SPLIT_%sC_%d_ADDR", in_ex,
 162                          *v6_incs);
 163                 setenv(envname, route, 1);
 164
 165                 snprintf(envname, 79, "CISCO_IPV6_SPLIT_%sC_%d_MASKLEN", in_ex,
 166                          *v6_incs);
 167                 setenv(envname, slash+1, 1);
 168
 169                 (*v6_incs)++;
 170                 return 0;
 171         }
 172
 173         if (!inet_aton(route, &addr)) {
 174                 *slash = '/';
 175                 goto badinc;
 176         }
 177
 178         envname[79] = 0;
 179         snprintf(envname, 79, "CISCO_SPLIT_%sC_%d_ADDR", in_ex, *v4_incs);
 180         setenv(envname, route, 1);
 181
 182         /* Put it back how we found it */
 183         *slash = '/';
 184
 185         if (!inet_aton(slash+1, &addr))
 186                 goto badinc;
 187
 188         snprintf(envname, 79, "CISCO_SPLIT_%sC_%d_MASK", in_ex, *v4_incs);
 189         setenv(envname, slash+1, 1);
 190
 191         snprintf(envname, 79, "CISCO_SPLIT_%sC_%d_MASKLEN", in_ex, *v4_incs);
 192         setenv_int(envname, netmasklen(addr));
 193
 194         (*v4_incs)++;
 195         return 0;
 196 }
 197
 198 static int appendenv(const char *opt, const char *new)
 199 {
 200         char buf[1024];
 201         char *old = getenv(opt);
 202
 203         buf[1023] = 0;
 204         if (old)
 205                 snprintf(buf, 1023, "%s %s", old, new);
 206         else
 207                 snprintf(buf, 1023, "%s", new);
 208
 209         return setenv(opt, buf, 1);
 210 }
 211
 212 static void setenv_cstp_opts(struct openconnect_info *vpninfo)
 213 {
 214         char *env_buf;
 215         int buflen = 0;
 216         int bufofs = 0;
 217         struct vpn_option *opt;
 218
 219         for (opt = vpninfo->cstp_options; opt; opt = opt->next)
 220                 buflen += 2 + strlen(opt->option) + strlen(opt->value);
 221
 222         env_buf = malloc(buflen + 1);
 223         if (!env_buf)
 224                 return;
 225
 226         env_buf[buflen] = 0;
 227
 228         for (opt = vpninfo->cstp_options; opt; opt = opt->next)
 229                 bufofs += snprintf(env_buf + bufofs, buflen - bufofs,
 230                                    "%s=%s\n", opt->option, opt->value);
 231
 232         setenv("CISCO_CSTP_OPTIONS", env_buf, 1);
 233         free(env_buf);
 234 }
 235
 236 static void set_script_env(struct openconnect_info *vpninfo)
 237 {
 238         char host[80];
 239         int ret = getnameinfo(vpninfo->peer_addr, vpninfo->peer_addrlen, host,
 240                               sizeof(host), NULL, 0, NI_NUMERICHOST);
 241         if (!ret)
 242                 setenv("VPNGATEWAY", host, 1);
 243         setenv("TUNDEV", vpninfo->ifname, 1);
 244         setenv("reason", "connect", 1);
 245         unsetenv("CISCO_BANNER");
 246         unsetenv("CISCO_SPLIT_INC");
 247         unsetenv("CISCO_SPLIT_EXC");
 248
 249         setenv_int("INTERNAL_IP4_MTU", vpninfo->mtu);
 250
 251         if (vpninfo->vpn_addr) {
 252                 setenv("INTERNAL_IP4_ADDRESS", vpninfo->vpn_addr, 1);
 253                 if (vpninfo->vpn_netmask) {
 254                         struct in_addr addr;
 255                         struct in_addr mask;
 256
 257                         if (inet_aton(vpninfo->vpn_addr, &addr) &&
 258                             inet_aton(vpninfo->vpn_netmask, &mask)) {
 259                                 char *netaddr;
 260
 261                                 addr.s_addr &= mask.s_addr;
 262                                 netaddr = inet_ntoa(addr);
 263
 264                                 setenv("INTERNAL_IP4_NETADDR", netaddr, 1);
 265                                 setenv("INTERNAL_IP4_NETMASK", vpninfo->vpn_netmask, 1);
 266                                 setenv_int("INTERNAL_IP4_NETMASKLEN", netmasklen(mask));
 267                         }
 268                 }
 269         }
 270         if (vpninfo->vpn_addr6) {
 271                 setenv("INTERNAL_IP6_ADDRESS", vpninfo->vpn_addr6, 1);
 272                 setenv("INTERNAL_IP6_NETMASK", vpninfo->vpn_netmask6, 1);
 273         }
 274
 275         if (vpninfo->vpn_dns[0])
 276                 setenv("INTERNAL_IP4_DNS", vpninfo->vpn_dns[0], 1);
 277         else
 278                 unsetenv("INTERNAL_IP4_DNS");
 279         if (vpninfo->vpn_dns[1])
 280                 appendenv("INTERNAL_IP4_DNS", vpninfo->vpn_dns[1]);
 281         if (vpninfo->vpn_dns[2])
 282                 appendenv("INTERNAL_IP4_DNS", vpninfo->vpn_dns[2]);
 283
 284         if (vpninfo->vpn_nbns[0])
 285                 setenv("INTERNAL_IP4_NBNS", vpninfo->vpn_nbns[0], 1);
 286         else
 287                 unsetenv("INTERNAL_IP4_NBNS");
 288         if (vpninfo->vpn_nbns[1])
 289                 appendenv("INTERNAL_IP4_NBNS", vpninfo->vpn_nbns[1]);
 290         if (vpninfo->vpn_nbns[2])
 291                 appendenv("INTERNAL_IP4_NBNS", vpninfo->vpn_nbns[2]);
 292
 293         if (vpninfo->vpn_domain)
 294                 setenv("CISCO_DEF_DOMAIN", vpninfo->vpn_domain, 1);
 295         else unsetenv ("CISCO_DEF_DOMAIN");
 296
 297         if (vpninfo->vpn_proxy_pac)
 298                 setenv("CISCO_PROXY_PAC", vpninfo->vpn_proxy_pac, 1);
 299
 300         if (vpninfo->split_includes) {
 301                 struct split_include *this = vpninfo->split_includes;
 302                 int nr_split_includes = 0;
 303                 int nr_v6_split_includes = 0;
 304
 305                 while (this) {
 306                         process_split_xxclude(vpninfo, "IN", this->route,
 307                                               &nr_split_includes,
 308                                               &nr_v6_split_includes);
 309                         this = this->next;
 310                 }
 311                 if (nr_split_includes)
 312                         setenv_int("CISCO_SPLIT_INC", nr_split_includes);
 313                 if (nr_v6_split_includes)
 314                         setenv_int("CISCO_IPV6_SPLIT_INC", nr_v6_split_includes);
 315         }
 316         if (vpninfo->split_excludes) {
 317                 struct split_include *this = vpninfo->split_excludes;
 318                 int nr_split_excludes = 0;
 319                 int nr_v6_split_excludes = 0;
 320
 321                 while (this) {
 322                         process_split_xxclude(vpninfo, "EX", this->route,
 323                                               &nr_split_excludes,
 324                                               &nr_v6_split_excludes);
 325                         this = this->next;
 326                 }
 327                 if (nr_split_excludes)
 328                         setenv_int("CISCO_SPLIT_EXC", nr_split_excludes);
 329                 if (nr_v6_split_excludes)
 330                         setenv_int("CISCO_IPV6_SPLIT_EXC", nr_v6_split_excludes);
 331         }
 332         setenv_cstp_opts(vpninfo);
 333 }
 334
 335 static int script_config_tun(struct openconnect_info *vpninfo)
 336 {
 337         set_script_env(vpninfo);
 338
 339         system(vpninfo->vpnc_script);
 340         return 0;
 341 }
 342
 343
 344 /* Set up a tuntap device. */
 345 int setup_tun(struct openconnect_info *vpninfo)
 346 {
 347         int tun_fd;
 348
 349         if (vpninfo->script_tun) {
 350                 pid_t child;
 351                 int fds[2];
 352
 353                 if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fds)) {
 354                         perror("socketpair");
 355                         exit(1);
 356                 }
 357                 tun_fd = fds[0];
 358                 child = fork();
 359                 if (child < 0) {
 360                         perror("fork");
 361                         exit(1);
 362                 } else if (!child) {
 363                         close(tun_fd);
 364                         setenv_int("VPNFD", fds[1]);
 365                         execl("/bin/sh", "/bin/sh", "-c", vpninfo->vpnc_script, NULL);
 366                         perror("execl");
 367                         exit(1);
 368                 }
 369                 close(fds[1]);
 370                 vpninfo->script_tun = child;
 371                 vpninfo->ifname = "(script)";
 372         } else {
 373 #ifdef IFF_TUN /* Linux */
 374                 struct ifreq ifr;
 375
 376                 tun_fd = open("/dev/net/tun", O_RDWR);
 377                 if (tun_fd < 0) {
 378                         vpninfo->progress(vpninfo, PRG_ERR,
 379                                           "Failed to open tun device: %s\n",
 380                                           strerror(errno));
 381                         exit(1);
 382                 }
 383                 memset(&ifr, 0, sizeof(ifr));
 384                 ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
 385                 if (vpninfo->ifname)
 386                         strncpy(ifr.ifr_name, vpninfo->ifname,
 387                                 sizeof(ifr.ifr_name) - 1);
 388                 if (ioctl(tun_fd, TUNSETIFF, (void *) &ifr) < 0) {
 389                         vpninfo->progress(vpninfo, PRG_ERR,
 390                                           "TUNSETIFF failed: %s\n",
 391                                           strerror(errno));
 392                         exit(1);
 393                 }
 394                 if (!vpninfo->ifname)
 395                         vpninfo->ifname = strdup(ifr.ifr_name);
 396 #elif defined (__sun__)
 397                 static char tun_name[80];
 398                 int tun2_fd, ip_fd = open("/dev/ip", O_RDWR);
 399                 int unit_nr, mux_id;
 400                 struct ifreq ifr;
 401
 402                 if (ip_fd < 0) {
 403                         perror("open /dev/ip");
 404                         return -EIO;
 405                 }
 406
 407                 tun_fd = open("/dev/tun", O_RDWR);
 408                 if (tun_fd < 0) {
 409                         perror("open /dev/tun");
 410                         close(ip_fd);
 411                         return -EIO;
 412                 }
 413
 414                 unit_nr = ioctl(tun_fd, TUNNEWPPA, -1);
 415                 if (unit_nr < 0) {
 416                         perror("Failed to create new tun");
 417                         close(tun_fd);
 418                         close(ip_fd);
 419                         return -EIO;
 420                 }
 421
 422                 tun2_fd = open("/dev/tun", O_RDWR);
 423                 if (tun2_fd < 0) {
 424                         perror("open /dev/tun again");
 425                         close(tun_fd);
 426                         close(ip_fd);
 427                         return -EIO;
 428                 }
 429                 if (ioctl(tun2_fd, I_PUSH, "ip") < 0) {
 430                         perror("Can't push IP");
 431                         close(tun2_fd);
 432                         close(tun_fd);
 433                         close(ip_fd);
 434                         return -EIO;
 435                 }
 436                 if (ioctl(tun2_fd, IF_UNITSEL, &unit_nr) < 0) {
 437                         perror("Can't select unit");
 438                         close(tun2_fd);
 439                         close(tun_fd);
 440                         close(ip_fd);
 441                         return -EIO;
 442                 }
 443                 mux_id = ioctl(ip_fd, I_PLINK, tun2_fd);
 444                 if (mux_id < 0) {
 445                         perror("Can't link tun to IP");
 446                         close(tun2_fd);
 447                         close(tun_fd);
 448                         close(ip_fd);
 449                         return -EIO;
 450                 }
 451                 close(tun2_fd);
 452
 453                 sprintf(tun_name, "tun%d", unit_nr);
 454                 vpninfo->ifname = tun_name;
 455
 456                 memset(&ifr, 0, sizeof(ifr));
 457                 strcpy(ifr.ifr_name, tun_name);
 458                 ifr.ifr_ip_muxid = mux_id;
 459
 460                 if (ioctl(ip_fd, SIOCSIFMUXID, &ifr) < 0) {
 461                         perror("Set mux id");
 462                         close(tun_fd);
 463                         ioctl(ip_fd, I_PUNLINK, mux_id);
 464                         close(ip_fd);
 465                         return -EIO;
 466                 }
 467                 /* Solaris tunctl needs this in order to tear it down */
 468                 vpninfo->progress(vpninfo, PRG_DEBUG, "mux id is %d\n", mux_id);
 469                 vpninfo->tun_muxid = mux_id;
 470                 vpninfo->ip_fd = ip_fd;
 471
 472 #else /* BSD et al have /dev/tun$x devices */
 473                 static char tun_name[80];
 474                 int i;
 475                 for (i = 0; i < 255; i++) {
 476                         sprintf(tun_name, "/dev/tun%d", i);
 477                         tun_fd = open(tun_name, O_RDWR);
 478                         if (tun_fd >= 0)
 479                                 break;
 480                 }
 481                 if (tun_fd < 0) {
 482                         perror("open tun");
 483                         exit(1);
 484                 }
 485                 vpninfo->ifname = tun_name + 5;
 486 #ifdef TUNSIFHEAD
 487                 i = 1;
 488                 if (ioctl(tun_fd, TUNSIFHEAD, &i) < 0) {
 489                         perror("TUNSIFHEAD");
 490                         exit(1);
 491                 }
 492 #endif
 493 #endif
 494                 if (vpninfo->vpnc_script) {
 495                         script_config_tun(vpninfo);
 496                         /* We have to set the MTU for ourselves, because the script doesn't */
 497                         local_config_tun(vpninfo, 1);
 498                 } else
 499                         local_config_tun(vpninfo, 0);
 500         }
 501
 502         fcntl(tun_fd, F_SETFD, FD_CLOEXEC);
 503
 504         vpninfo->tun_fd = tun_fd;
 505
 506         if (vpninfo->select_nfds <= tun_fd)
 507                 vpninfo->select_nfds = tun_fd + 1;
 508
 509         FD_SET(tun_fd, &vpninfo->select_rfds);
 510
 511         fcntl(vpninfo->tun_fd, F_SETFL, fcntl(vpninfo->tun_fd, F_GETFL) | O_NONBLOCK);
 512
 513         return 0;
 514 }
 515
 516 int tun_mainloop(struct openconnect_info *vpninfo, int *timeout)
 517 {
 518         unsigned char buf[2000];
 519         int len;
 520         int work_done = 0;
 521
 522         if (FD_ISSET(vpninfo->tun_fd, &vpninfo->select_rfds)) {
 523                 while ((len = read(vpninfo->tun_fd, buf, sizeof(buf))) > 0) {
 524                         unsigned char *pkt = buf;
 525 #ifdef TUN_HAS_AF_PREFIX
 526                         pkt += 4;
 527                         len -= 4;
 528 #endif
 529                         if (queue_new_packet(&vpninfo->outgoing_queue, pkt,
 530                                              len))
 531                                 break;
 532
 533                         work_done = 1;
 534                         vpninfo->outgoing_qlen++;
 535                         if (vpninfo->outgoing_qlen == vpninfo->max_qlen) {
 536                                 FD_CLR(vpninfo->tun_fd, &vpninfo->select_rfds);
 537                                 break;
 538                         }
 539                 }
 540         } else if (vpninfo->outgoing_qlen < vpninfo->max_qlen) {
 541                 FD_SET(vpninfo->tun_fd, &vpninfo->select_rfds);
 542         }
 543
 544         /* The kernel returns -ENOMEM when the queue is full, so theoretically
 545            we could handle that and retry... but it doesn't let us poll() for
 546            the no-longer-full situation, so let's not bother. */
 547         while (vpninfo->incoming_queue) {
 548                 struct pkt *this = vpninfo->incoming_queue;
 549                 unsigned char *data = this->data;
 550                 int len = this->len;
 551
 552 #ifdef TUN_HAS_AF_PREFIX
 553                 struct ip *iph = (void *)data;
 554                 int type;
 555
 556                 if (iph->ip_v == 6)
 557                         type = AF_INET6;
 558                 else if (iph->ip_v == 4)
 559                         type = AF_INET;
 560                 else {
 561                         static int complained = 0;
 562                         if (!complained) {
 563                                 complained = 1;
 564                                 vpninfo->progress(vpninfo, PRG_ERR,
 565                                                   "Unknown packet (len %d) received: %02x %02x %02x %02x...\n",
 566                                                   len, data[0], data[1], data[2], data[3]);
 567                         }
 568                         free(this);
 569                         continue;
 570                 }
 571                 data -= 4;
 572                 len += 4;
 573                 *(int *)data = htonl(type);
 574 #endif
 575                 vpninfo->incoming_queue = this->next;
 576
 577                 if (write(vpninfo->tun_fd, data, len) < 0 &&
 578                     errno == ENOTCONN) {
 579                         vpninfo->quit_reason = "Client connection terminated";
 580                         return 1;
 581                 }
 582                 free(this);
 583         }
 584         /* Work is not done if we just got rid of packets off the queue */
 585         return work_done;
 586 }
 587
 588 void shutdown_tun(struct openconnect_info *vpninfo)
 589 {
 590         if (vpninfo->script_tun) {
 591                 kill(vpninfo->script_tun, SIGHUP);
 592         } else {
 593                 if (vpninfo->vpnc_script) {
 594                         setenv("TUNDEV", vpninfo->ifname, 1);
 595                         setenv("reason", "disconnect", 1);
 596                         system(vpninfo->vpnc_script);
 597                 }
 598 #ifdef __sun__
 599                 if (ioctl(vpninfo->ip_fd, I_PUNLINK, vpninfo->tun_muxid) < 0)
 600                         perror("ioctl(I_PUNLINK)");
 601
 602                 close(vpninfo->ip_fd);
 603                 vpninfo->ip_fd = -1;
 604 #endif
 605         }
 606
 607         close(vpninfo->tun_fd);
 608         vpninfo->tun_fd = -1;
 609 }