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 <netinet/in_systm.h>
  34 #include <netinet/in.h>
  35 #include <netinet/ip.h>
  36 #include <net/if.h>
  37 #include <arpa/inet.h>
  38 #include <errno.h>
  39 #if defined(__sun__)
  40 #include <net/if_tun.h>
  41 #include <stropts.h>
  42 #include <sys/sockio.h>
  43 #endif
  44
  45 #include "openconnect.h"
  46
  47 /*
  48  * If an if_tun.h include file was found anywhere (by the Makefile), it's
  49  * included. Else, we end up assuming that we have BSD-style devices such
  50  * as /dev/tun0 etc.
  51  */
  52 #ifdef IF_TUN_HDR
  53 #include IF_TUN_HDR
  54 #endif
  55
  56 /*
  57  * The OS X tun/tap driver doesn't provide a header file; you're expected
  58  * to define this for yourself.
  59  */
  60 #ifdef __APPLE__
  61 #define TUNSIFHEAD  _IOW('t', 96, int)
  62 #endif
  63
  64 /*
  65  * OpenBSD always puts the protocol family prefix onto packets. Other
  66  * systems let us enable that with the TUNSIFHEAD ioctl, and some of them
  67  * (e.g. FreeBSD) _need_ it otherwise they'll interpret IPv6 packets as IPv4.
  68  */
  69 #if defined(__OpenBSD__) || defined(TUNSIFHEAD)
  70 #define TUN_HAS_AF_PREFIX 1
  71 #endif
  72
  73 #ifdef __sun__
  74 static int local_config_tun(struct openconnect_info *vpninfo, int mtu_only)
  75 {
  76         if (!mtu_only)
  77                 vpninfo->progress(vpninfo, PRG_ERR,
  78                                   "No vpnc-script configured. Need Solaris IP-setting code\n");
  79         return 0;
  80 }
  81 #else
  82 static int local_config_tun(struct openconnect_info *vpninfo, int mtu_only)
  83 {
  84         struct ifreq ifr;
  85         int net_fd;
  86
  87         net_fd = socket(PF_INET, SOCK_DGRAM, 0);
  88         if (net_fd < 0) {
  89                 perror("open net");
  90                 return -EINVAL;
  91         }
  92         memset(&ifr, 0, sizeof(ifr));
  93         strncpy(ifr.ifr_name, vpninfo->ifname, sizeof(ifr.ifr_name) - 1);
  94
  95         if (!mtu_only) {
  96                 struct sockaddr_in addr;
  97
  98                 if (ioctl(net_fd, SIOCGIFFLAGS, &ifr) < 0)
  99                         perror("SIOCGIFFLAGS");
 100
 101                 ifr.ifr_flags |= IFF_UP | IFF_POINTOPOINT;
 102                 if (ioctl(net_fd, SIOCSIFFLAGS, &ifr) < 0)
 103                         perror("SIOCSIFFLAGS");
 104
 105                 addr.sin_family = AF_INET;
 106                 addr.sin_addr.s_addr = inet_addr(vpninfo->vpn_addr);
 107                 memcpy(&ifr.ifr_addr, &addr, sizeof(addr));
 108                 if (ioctl(net_fd, SIOCSIFADDR, &ifr) < 0)
 109                         perror("SIOCSIFADDR");
 110         }
 111
 112         ifr.ifr_mtu = vpninfo->mtu;
 113         if (ioctl(net_fd, SIOCSIFMTU, &ifr) < 0)
 114                 perror("SIOCSIFMTU");
 115
 116         close(net_fd);
 117
 118         return 0;
 119 }
 120 #endif
 121
 122 static int setenv_int(const char *opt, int value)
 123 {
 124         char buf[16];
 125         sprintf(buf, "%d", value);
 126         return setenv(opt, buf, 1);
 127 }
 128
 129 static int netmasklen(struct in_addr addr)
 130 {
 131         int masklen;
 132
 133         for (masklen = 0; masklen < 32; masklen++) {
 134                 if (ntohl(addr.s_addr) >= (0xffffffff << masklen))
 135                         break;
 136         }
 137         return 32 - masklen;
 138 }
 139
 140 static int process_split_xxclude(struct openconnect_info *vpninfo,
 141                                  char *in_ex, char *route, int *v4_incs,
 142                                  int *v6_incs)
 143 {
 144         struct in_addr addr;
 145         char envname[80];
 146         char *slash;
 147
 148         slash = strchr(route, '/');
 149         if (!slash) {
 150         badinc:
 151                 vpninfo->progress(vpninfo, PRG_ERR,
 152                                   "Discard bad split %sclude: \"%s\"\n",
 153                                   in_ex, route);
 154                 return -EINVAL;
 155         }
 156
 157         *slash = 0;
 158
 159         if (strchr(route, ':')) {
 160                 snprintf(envname, 79, "CISCO_IPV6_SPLIT_%sC_%d_ADDR", in_ex,
 161                          *v6_incs);
 162                 setenv(envname, route, 1);
 163
 164                 snprintf(envname, 79, "CISCO_IPV6_SPLIT_%sC_%d_MASKLEN", in_ex,
 165                          *v6_incs);
 166                 setenv(envname, slash+1, 1);
 167
 168                 (*v6_incs)++;
 169                 return 0;
 170         }
 171
 172         if (!inet_aton(route, &addr)) {
 173                 *slash = '/';
 174                 goto badinc;
 175         }
 176
 177         envname[79] = 0;
 178         snprintf(envname, 79, "CISCO_SPLIT_%sC_%d_ADDR", in_ex, *v4_incs);
 179         setenv(envname, route, 1);
 180
 181         /* Put it back how we found it */
 182         *slash = '/';
 183
 184         if (!inet_aton(slash+1, &addr))
 185                 goto badinc;
 186
 187         snprintf(envname, 79, "CISCO_SPLIT_%sC_%d_MASK", in_ex, *v4_incs);
 188         setenv(envname, slash+1, 1);
 189
 190         snprintf(envname, 79, "CISCO_SPLIT_%sC_%d_MASKLEN", in_ex, *v4_incs);
 191         setenv_int(envname, netmasklen(addr));
 192
 193         (*v4_incs)++;
 194         return 0;
 195 }
 196
 197 static int appendenv(const char *opt, const char *new)
 198 {
 199         char buf[1024];
 200         char *old = getenv(opt);
 201
 202         buf[1023] = 0;
 203         if (old)
 204                 snprintf(buf, 1023, "%s %s", old, new);
 205         else
 206                 snprintf(buf, 1023, "%s", new);
 207
 208         return setenv(opt, buf, 1);
 209 }
 210
 211 static void setenv_cstp_opts(struct openconnect_info *vpninfo)
 212 {
 213         char *env_buf;
 214         int buflen = 0;
 215         int bufofs = 0;
 216         struct vpn_option *opt;
 217
 218         for (opt = vpninfo->cstp_options; opt; opt = opt->next)
 219                 buflen += 2 + strlen(opt->option) + strlen(opt->value);
 220
 221         env_buf = malloc(buflen + 1);
 222         if (!env_buf)
 223                 return;
 224
 225         env_buf[buflen] = 0;
 226
 227         for (opt = vpninfo->cstp_options; opt; opt = opt->next)
 228                 bufofs += snprintf(env_buf + bufofs, buflen - bufofs,
 229                                    "%s=%s\n", opt->option, opt->value);
 230
 231         setenv("CISCO_CSTP_OPTIONS", env_buf, 1);
 232         free(env_buf);
 233 }
 234
 235 static void set_script_env(struct openconnect_info *vpninfo)
 236 {
 237         struct sockaddr_in *sin = (void *)vpninfo->peer_addr;
 238
 239         setenv("VPNGATEWAY", inet_ntoa(sin->sin_addr), 1);
 240         setenv("TUNDEV", vpninfo->ifname, 1);
 241         setenv("reason", "connect", 1);
 242         unsetenv("CISCO_BANNER");
 243         unsetenv("CISCO_SPLIT_INC");
 244         unsetenv("CISCO_SPLIT_EXC");
 245
 246         setenv_int("INTERNAL_IP4_MTU", vpninfo->mtu);
 247
 248         if (vpninfo->vpn_addr) {
 249                 setenv("INTERNAL_IP4_ADDRESS", vpninfo->vpn_addr, 1);
 250                 if (vpninfo->vpn_netmask) {
 251                         struct in_addr addr;
 252                         struct in_addr mask;
 253
 254                         if (inet_aton(vpninfo->vpn_addr, &addr) &&
 255                             inet_aton(vpninfo->vpn_netmask, &mask)) {
 256                                 char *netaddr;
 257
 258                                 addr.s_addr &= mask.s_addr;
 259                                 netaddr = inet_ntoa(addr);
 260
 261                                 setenv("INTERNAL_IP4_NETADDR", netaddr, 1);
 262                                 setenv("INTERNAL_IP4_NETMASK", vpninfo->vpn_netmask, 1);
 263                                 setenv_int("INTERNAL_IP4_NETMASKLEN", netmasklen(mask));
 264                         }
 265                 }
 266         }
 267         if (vpninfo->vpn_addr6) {
 268                 setenv("INTERNAL_IP6_ADDRESS", vpninfo->vpn_addr6, 1);
 269                 setenv("INTERNAL_IP6_NETMASK", vpninfo->vpn_netmask6, 1);
 270         }
 271
 272         if (vpninfo->vpn_dns[0])
 273                 setenv("INTERNAL_IP4_DNS", vpninfo->vpn_dns[0], 1);
 274         else
 275                 unsetenv("INTERNAL_IP4_DNS");
 276         if (vpninfo->vpn_dns[1])
 277                 appendenv("INTERNAL_IP4_DNS", vpninfo->vpn_dns[1]);
 278         if (vpninfo->vpn_dns[2])
 279                 appendenv("INTERNAL_IP4_DNS", vpninfo->vpn_dns[2]);
 280
 281         if (vpninfo->vpn_nbns[0])
 282                 setenv("INTERNAL_IP4_NBNS", vpninfo->vpn_nbns[0], 1);
 283         else
 284                 unsetenv("INTERNAL_IP4_NBNS");
 285         if (vpninfo->vpn_nbns[1])
 286                 appendenv("INTERNAL_IP4_NBNS", vpninfo->vpn_nbns[1]);
 287         if (vpninfo->vpn_nbns[2])
 288                 appendenv("INTERNAL_IP4_NBNS", vpninfo->vpn_nbns[2]);
 289
 290         if (vpninfo->vpn_domain)
 291                 setenv("CISCO_DEF_DOMAIN", vpninfo->vpn_domain, 1);
 292         else unsetenv ("CISCO_DEF_DOMAIN");
 293
 294         if (vpninfo->vpn_proxy_pac)
 295                 setenv("CISCO_PROXY_PAC", vpninfo->vpn_proxy_pac, 1);
 296
 297         if (vpninfo->split_includes) {
 298                 struct split_include *this = vpninfo->split_includes;
 299                 int nr_split_includes = 0;
 300                 int nr_v6_split_includes = 0;
 301
 302                 while (this) {
 303                         process_split_xxclude(vpninfo, "IN", this->route,
 304                                               &nr_split_includes,
 305                                               &nr_v6_split_includes);
 306                         this = this->next;
 307                 }
 308                 if (nr_split_includes)
 309                         setenv_int("CISCO_SPLIT_INC", nr_split_includes);
 310                 if (nr_v6_split_includes)
 311                         setenv_int("CISCO_IPV6_SPLIT_INC", nr_v6_split_includes);
 312         }
 313         if (vpninfo->split_excludes) {
 314                 struct split_include *this = vpninfo->split_excludes;
 315                 int nr_split_excludes = 0;
 316                 int nr_v6_split_excludes = 0;
 317
 318                 while (this) {
 319                         process_split_xxclude(vpninfo, "EX", this->route,
 320                                               &nr_split_excludes,
 321                                               &nr_v6_split_excludes);
 322                         this = this->next;
 323                 }
 324                 if (nr_split_excludes)
 325                         setenv_int("CISCO_SPLIT_EXC", nr_split_excludes);
 326                 if (nr_v6_split_excludes)
 327                         setenv_int("CISCO_IPV6_SPLIT_EXC", nr_v6_split_excludes);
 328         }
 329         setenv_cstp_opts(vpninfo);
 330 }
 331
 332 static int script_config_tun(struct openconnect_info *vpninfo)
 333 {
 334         if (vpninfo->peer_addr->sa_family != AF_INET || !vpninfo->vpn_addr) {
 335                 vpninfo->progress(vpninfo, PRG_ERR,
 336                                   "Script can only handle Legacy IP\n");
 337                 return -EINVAL;
 338         }
 339
 340         set_script_env(vpninfo);
 341
 342         system(vpninfo->vpnc_script);
 343         return 0;
 344 }
 345
 346
 347 /* Set up a tuntap device. */
 348 int setup_tun(struct openconnect_info *vpninfo)
 349 {
 350         int tun_fd;
 351
 352         if (vpninfo->script_tun) {
 353                 pid_t child;
 354                 int fds[2];
 355
 356                 if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fds)) {
 357                         perror("socketpair");
 358                         exit(1);
 359                 }
 360                 tun_fd = fds[0];
 361                 child = fork();
 362                 if (child < 0) {
 363                         perror("fork");
 364                         exit(1);
 365                 } else if (!child) {
 366                         close(tun_fd);
 367                         setenv_int("VPNFD", fds[1]);
 368                         execl("/bin/sh", "/bin/sh", "-c", vpninfo->vpnc_script, NULL);
 369                         perror("execl");
 370                         exit(1);
 371                 }
 372                 close(fds[1]);
 373                 vpninfo->script_tun = child;
 374                 vpninfo->ifname = "(script)";
 375         } else {
 376 #ifdef IFF_TUN /* Linux */
 377                 struct ifreq ifr;
 378
 379                 tun_fd = open("/dev/net/tun", O_RDWR);
 380                 if (tun_fd < 0) {
 381                         vpninfo->progress(vpninfo, PRG_ERR,
 382                                           "Failed to open tun device: %s\n",
 383                                           strerror(errno));
 384                         exit(1);
 385                 }
 386                 memset(&ifr, 0, sizeof(ifr));
 387                 ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
 388                 if (vpninfo->ifname)
 389                         strncpy(ifr.ifr_name, vpninfo->ifname,
 390                                 sizeof(ifr.ifr_name) - 1);
 391                 if (ioctl(tun_fd, TUNSETIFF, (void *) &ifr) < 0) {
 392                         vpninfo->progress(vpninfo, PRG_ERR,
 393                                           "TUNSETIFF failed: %s\n",
 394                                           strerror(errno));
 395                         exit(1);
 396                 }
 397                 if (!vpninfo->ifname)
 398                         vpninfo->ifname = strdup(ifr.ifr_name);
 399 #elif defined (__sun__)
 400                 static char tun_name[80];
 401                 int tun2_fd, ip_fd = open("/dev/ip", O_RDWR);
 402                 int unit_nr, mux_id;
 403                 struct ifreq ifr;
 404
 405                 if (ip_fd < 0) {
 406                         perror("open /dev/ip");
 407                         return -EIO;
 408                 }
 409
 410                 tun_fd = open("/dev/tun", O_RDWR);
 411                 if (tun_fd < 0) {
 412                         perror("open /dev/tun");
 413                         close(ip_fd);
 414                         return -EIO;
 415                 }
 416
 417                 unit_nr = ioctl(tun_fd, TUNNEWPPA, -1);
 418                 if (unit_nr < 0) {
 419                         perror("Failed to create new tun");
 420                         close(tun_fd);
 421                         close(ip_fd);
 422                         return -EIO;
 423                 }
 424
 425                 tun2_fd = open("/dev/tun", O_RDWR);
 426                 if (tun2_fd < 0) {
 427                         perror("open /dev/tun again");
 428                         close(tun_fd);
 429                         close(ip_fd);
 430                         return -EIO;
 431                 }
 432                 if (ioctl(tun2_fd, I_PUSH, "ip") < 0) {
 433                         perror("Can't push IP");
 434                         close(tun2_fd);
 435                         close(tun_fd);
 436                         close(ip_fd);
 437                         return -EIO;
 438                 }
 439                 if (ioctl(tun2_fd, IF_UNITSEL, &unit_nr) < 0) {
 440                         perror("Can't select unit");
 441                         close(tun2_fd);
 442                         close(tun_fd);
 443                         close(ip_fd);
 444                         return -EIO;
 445                 }
 446                 mux_id = ioctl(ip_fd, I_PLINK, tun2_fd);
 447                 if (mux_id < 0) {
 448                         perror("Can't link tun to IP");
 449                         close(tun2_fd);
 450                         close(tun_fd);
 451                         close(ip_fd);
 452                         return -EIO;
 453                 }
 454                 close(tun2_fd);
 455
 456                 sprintf(tun_name, "tun%d", unit_nr);
 457                 vpninfo->ifname = tun_name;
 458
 459                 memset(&ifr, 0, sizeof(ifr));
 460                 strcpy(ifr.ifr_name, tun_name);
 461                 ifr.ifr_ip_muxid = mux_id;
 462
 463                 if (ioctl(ip_fd, SIOCSIFMUXID, &ifr) < 0) {
 464                         perror("Set mux id");
 465                         close(tun_fd);
 466                         ioctl(ip_fd, I_PUNLINK, mux_id);
 467                         close(ip_fd);
 468                         return -EIO;
 469                 }
 470                 /* Solaris tunctl needs this in order to tear it down */
 471                 vpninfo->progress(vpninfo, PRG_DEBUG, "mux id is %d\n", mux_id);
 472                 vpninfo->tun_muxid = mux_id;
 473                 vpninfo->ip_fd = ip_fd;
 474
 475 #else /* BSD et al have /dev/tun$x devices */
 476                 static char tun_name[80];
 477                 int i;
 478                 for (i = 0; i < 255; i++) {
 479                         sprintf(tun_name, "/dev/tun%d", i);
 480                         tun_fd = open(tun_name, O_RDWR);
 481                         if (tun_fd >= 0)
 482                                 break;
 483                 }
 484                 if (tun_fd < 0) {
 485                         perror("open tun");
 486                         exit(1);
 487                 }
 488                 vpninfo->ifname = tun_name + 5;
 489 #ifdef TUNSIFHEAD
 490                 i = 1;
 491                 if (ioctl(tun_fd, TUNSIFHEAD, &i) < 0) {
 492                         perror("TUNSIFHEAD");
 493                         exit(1);
 494                 }
 495 #endif
 496 #endif
 497                 if (vpninfo->vpnc_script) {
 498                         script_config_tun(vpninfo);
 499                         /* We have to set the MTU for ourselves, because the script doesn't */
 500                         local_config_tun(vpninfo, 1);
 501                 } else
 502                         local_config_tun(vpninfo, 0);
 503         }
 504
 505         fcntl(tun_fd, F_SETFD, FD_CLOEXEC);
 506
 507         vpninfo->tun_fd = tun_fd;
 508
 509         if (vpninfo->select_nfds <= tun_fd)
 510                 vpninfo->select_nfds = tun_fd + 1;
 511
 512         FD_SET(tun_fd, &vpninfo->select_rfds);
 513
 514         fcntl(vpninfo->tun_fd, F_SETFL, fcntl(vpninfo->tun_fd, F_GETFL) | O_NONBLOCK);
 515
 516         return 0;
 517 }
 518
 519 int tun_mainloop(struct openconnect_info *vpninfo, int *timeout)
 520 {
 521         unsigned char buf[2000];
 522         int len;
 523         int work_done = 0;
 524
 525         if (FD_ISSET(vpninfo->tun_fd, &vpninfo->select_rfds)) {
 526                 while ((len = read(vpninfo->tun_fd, buf, sizeof(buf))) > 0) {
 527                         unsigned char *pkt = buf;
 528 #ifdef TUN_HAS_AF_PREFIX
 529                         pkt += 4;
 530                         len -= 4;
 531 #endif
 532                         if (queue_new_packet(&vpninfo->outgoing_queue, pkt,
 533                                              len))
 534                                 break;
 535
 536                         work_done = 1;
 537                         vpninfo->outgoing_qlen++;
 538                         if (vpninfo->outgoing_qlen == vpninfo->max_qlen) {
 539                                 FD_CLR(vpninfo->tun_fd, &vpninfo->select_rfds);
 540                                 break;
 541                         }
 542                 }
 543         } else if (vpninfo->outgoing_qlen < vpninfo->max_qlen) {
 544                 FD_SET(vpninfo->tun_fd, &vpninfo->select_rfds);
 545         }
 546
 547         /* The kernel returns -ENOMEM when the queue is full, so theoretically
 548            we could handle that and retry... but it doesn't let us poll() for
 549            the no-longer-full situation, so let's not bother. */
 550         while (vpninfo->incoming_queue) {
 551                 struct pkt *this = vpninfo->incoming_queue;
 552                 unsigned char *data = this->data;
 553                 int len = this->len;
 554
 555 #ifdef TUN_HAS_AF_PREFIX
 556                 struct ip *iph = (void *)data;
 557                 int type;
 558
 559                 if (iph->ip_v == 6)
 560                         type = AF_INET6;
 561                 else if (iph->ip_v == 4)
 562                         type = AF_INET;
 563                 else {
 564                         static int complained = 0;
 565                         if (!complained) {
 566                                 complained = 1;
 567                                 vpninfo->progress(vpninfo, PRG_ERR,
 568                                                   "Unknown packet (len %d) received: %02x %02x %02x %02x...\n",
 569                                                   len, data[0], data[1], data[2], data[3]);
 570                         }
 571                         free(this);
 572                         continue;
 573                 }
 574                 data -= 4;
 575                 len += 4;
 576                 *(int *)data = htonl(type);
 577 #endif
 578                 vpninfo->incoming_queue = this->next;
 579
 580                 if (write(vpninfo->tun_fd, data, len) < 0 &&
 581                     errno == ENOTCONN) {
 582                         vpninfo->quit_reason = "Client connection terminated";
 583                         return 1;
 584                 }
 585                 free(this);
 586         }
 587         /* Work is not done if we just got rid of packets off the queue */
 588         return work_done;
 589 }
 590
 591 void shutdown_tun(struct openconnect_info *vpninfo)
 592 {
 593         if (vpninfo->script_tun) {
 594                 kill(vpninfo->script_tun, SIGHUP);
 595         } else {
 596                 if (vpninfo->vpnc_script) {
 597                         setenv("TUNDEV", vpninfo->ifname, 1);
 598                         setenv("reason", "disconnect", 1);
 599                         system(vpninfo->vpnc_script);
 600                 }
 601 #ifdef __sun__
 602                 if (ioctl(vpninfo->ip_fd, I_PUNLINK, vpninfo->tun_muxid) < 0)
 603                         perror("ioctl(I_PUNLINK)");
 604
 605                 close(vpninfo->ip_fd);
 606                 vpninfo->ip_fd = -1;
 607 #endif
 608         }
 609
 610         close(vpninfo->tun_fd);
 611         vpninfo->tun_fd = -1;
 612 }