git.tinc-vpn.org Git - tinc/blob - src/linux/device.c

   1 /*
   2     device.c -- Interaction with Linux ethertap and tun/tap device
   3     Copyright (C) 2001-2005 Ivo Timmermans,
   4                   2001-2014 Guus Sliepen <guus@tinc-vpn.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "../system.h"
  22
  23 #ifdef HAVE_LINUX_IF_TUN_H
  24 #include <linux/if_tun.h>
  25 #define DEFAULT_DEVICE "/dev/net/tun"
  26 #else
  27 #define DEFAULT_DEVICE "/dev/tap0"
  28 #endif
  29
  30 #include "../conf.h"
  31 #include "../device.h"
  32 #include "../logger.h"
  33 #include "../net.h"
  34 #include "../route.h"
  35 #include "../utils.h"
  36 #include "../xalloc.h"
  37
  38 typedef enum device_type_t {
  39         DEVICE_TYPE_ETHERTAP,
  40         DEVICE_TYPE_TUN,
  41         DEVICE_TYPE_TAP,
  42 } device_type_t;
  43
  44 int device_fd = -1;
  45 static device_type_t device_type;
  46 char *device = NULL;
  47 char *iface = NULL;
  48 static char *type = NULL;
  49 static char ifrname[IFNAMSIZ];
  50 static const char *device_info;
  51
  52 static uint64_t device_total_in = 0;
  53 static uint64_t device_total_out = 0;
  54
  55 static bool setup_device(void) {
  56         struct ifreq ifr;
  57         bool t1q = false;
  58
  59         if(!get_config_string(lookup_config(config_tree, "Device"), &device)) {
  60                 device = xstrdup(DEFAULT_DEVICE);
  61         }
  62
  63         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  64 #ifdef HAVE_LINUX_IF_TUN_H
  65                 if(netname != NULL) {
  66                         iface = xstrdup(netname);
  67                 }
  68
  69 #else
  70                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
  71 #endif
  72         device_fd = open(device, O_RDWR | O_NONBLOCK);
  73
  74         if(device_fd < 0) {
  75                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  76                 return false;
  77         }
  78
  79 #ifdef FD_CLOEXEC
  80         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
  81 #endif
  82
  83 #ifdef HAVE_LINUX_IF_TUN_H
  84         /* Ok now check if this is an old ethertap or a new tun/tap thingie */
  85
  86         memset(&ifr, 0, sizeof(ifr));
  87
  88         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
  89
  90         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
  91                 logger(LOG_ERR, "Unknown device type %s!", type);
  92                 return false;
  93         }
  94
  95         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
  96                 ifr.ifr_flags = IFF_TUN;
  97                 device_type = DEVICE_TYPE_TUN;
  98                 device_info = "Linux tun/tap device (tun mode)";
  99         } else {
 100                 if(routing_mode == RMODE_ROUTER) {
 101                         overwrite_mac = true;
 102                 }
 103
 104                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
 105                 device_type = DEVICE_TYPE_TAP;
 106                 device_info = "Linux tun/tap device (tap mode)";
 107         }
 108
 109 #ifdef IFF_ONE_QUEUE
 110
 111         /* Set IFF_ONE_QUEUE flag... */
 112         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q) {
 113                 ifr.ifr_flags |= IFF_ONE_QUEUE;
 114         }
 115
 116 #endif
 117
 118         if(iface) {
 119                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
 120                 ifr.ifr_name[IFNAMSIZ - 1] = 0;
 121         }
 122
 123         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
 124                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 125                 ifrname[IFNAMSIZ - 1] = 0;
 126                 free(iface);
 127                 iface = xstrdup(ifrname);
 128         } else if(errno == EPERM || errno == EBUSY) {
 129                 logger(LOG_ERR, "Error while trying to configure %s: %s", device, strerror(errno));
 130                 return false;
 131         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
 132                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
 133                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 134                 ifrname[IFNAMSIZ - 1] = 0;
 135                 free(iface);
 136                 iface = xstrdup(ifrname);
 137         } else
 138 #endif
 139         {
 140                 if(routing_mode == RMODE_ROUTER) {
 141                         overwrite_mac = true;
 142                 }
 143
 144                 device_info = "Linux ethertap device";
 145                 device_type = DEVICE_TYPE_ETHERTAP;
 146                 free(iface);
 147                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
 148         }
 149
 150         if(overwrite_mac && !ioctl(device_fd, SIOCGIFHWADDR, &ifr)) {
 151                 memcpy(mymac.x, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
 152         }
 153
 154         logger(LOG_INFO, "%s is a %s", device, device_info);
 155
 156         return true;
 157 }
 158
 159 static void close_device(void) {
 160         close(device_fd);
 161
 162         free(type);
 163         free(device);
 164         free(iface);
 165 }
 166
 167 static bool read_packet(vpn_packet_t *packet) {
 168         int lenin;
 169
 170         switch(device_type) {
 171         case DEVICE_TYPE_TUN:
 172                 lenin = read(device_fd, packet->data + 10, MTU - 10);
 173
 174                 if(lenin <= 0) {
 175                         logger(LOG_ERR, "Error while reading from %s %s: %s",
 176                                device_info, device, strerror(errno));
 177                         return false;
 178                 }
 179
 180                 memset(packet->data, 0, 12);
 181                 packet->len = lenin + 10;
 182                 break;
 183
 184         case DEVICE_TYPE_TAP:
 185                 lenin = read(device_fd, packet->data, MTU);
 186
 187                 if(lenin <= 0) {
 188                         logger(LOG_ERR, "Error while reading from %s %s: %s",
 189                                device_info, device, strerror(errno));
 190                         return false;
 191                 }
 192
 193                 packet->len = lenin;
 194                 break;
 195
 196         case DEVICE_TYPE_ETHERTAP:
 197                 lenin = read(device_fd, packet->data - 2, MTU + 2);
 198
 199                 if(lenin <= 0) {
 200                         logger(LOG_ERR, "Error while reading from %s %s: %s",
 201                                device_info, device, strerror(errno));
 202                         return false;
 203                 }
 204
 205                 packet->len = lenin - 2;
 206                 break;
 207         }
 208
 209         device_total_in += packet->len;
 210
 211         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 212                                 device_info);
 213
 214         return true;
 215 }
 216
 217 static bool write_packet(vpn_packet_t *packet) {
 218         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
 219                                 packet->len, device_info);
 220
 221         switch(device_type) {
 222         case DEVICE_TYPE_TUN:
 223                 packet->data[10] = packet->data[11] = 0;
 224
 225                 if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
 226                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 227                                strerror(errno));
 228                         return false;
 229                 }
 230
 231                 break;
 232
 233         case DEVICE_TYPE_TAP:
 234                 if(write(device_fd, packet->data, packet->len) < 0) {
 235                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 236                                strerror(errno));
 237                         return false;
 238                 }
 239
 240                 break;
 241
 242         case DEVICE_TYPE_ETHERTAP:
 243                 memcpy(packet->data - 2, &packet->len, 2);
 244
 245                 if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
 246                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 247                                strerror(errno));
 248                         return false;
 249                 }
 250
 251                 break;
 252         }
 253
 254         device_total_out += packet->len;
 255
 256         return true;
 257 }
 258
 259 static void dump_device_stats(void) {
 260         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
 261         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_total_in);
 262         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
 263 }
 264
 265 const devops_t os_devops = {
 266         .setup = setup_device,
 267         .close = close_device,
 268         .read = read_packet,
 269         .write = write_packet,
 270         .dump_stats = dump_device_stats,
 271 };