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