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