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