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