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 #include <linux/if_tun.h>
  24 #define DEFAULT_DEVICE "/dev/net/tun"
  25
  26 #include "../conf.h"
  27 #include "../device.h"
  28 #include "../logger.h"
  29 #include "../names.h"
  30 #include "../net.h"
  31 #include "../route.h"
  32 #include "../utils.h"
  33 #include "../xalloc.h"
  34 #include "../device.h"
  35
  36 typedef enum device_type_t {
  37         DEVICE_TYPE_TUN,
  38         DEVICE_TYPE_TAP,
  39 } device_type_t;
  40
  41 int device_fd = -1;
  42 static device_type_t device_type;
  43 char *device = NULL;
  44 char *iface = NULL;
  45 static char *type = NULL;
  46 static char ifrname[IFNAMSIZ];
  47 static const char *device_info;
  48
  49 static bool setup_device(void) {
  50         if(!get_config_string(lookup_config(config_tree, "Device"), &device)) {
  51                 device = xstrdup(DEFAULT_DEVICE);
  52         }
  53
  54         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  55                 if(netname) {
  56                         iface = xstrdup(netname);
  57                 }
  58
  59         device_fd = open(device, O_RDWR | O_NONBLOCK);
  60
  61         if(device_fd < 0) {
  62                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  63                 return false;
  64         }
  65
  66 #ifdef FD_CLOEXEC
  67         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
  68 #endif
  69
  70         struct ifreq ifr = {0};
  71
  72         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
  73
  74         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
  75                 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown device type %s!", type);
  76                 return false;
  77         }
  78
  79         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
  80                 ifr.ifr_flags = IFF_TUN;
  81                 device_type = DEVICE_TYPE_TUN;
  82                 device_info = "Linux tun/tap device (tun mode)";
  83         } else {
  84                 if(routing_mode == RMODE_ROUTER) {
  85                         overwrite_mac = true;
  86                 }
  87
  88                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  89                 device_type = DEVICE_TYPE_TAP;
  90                 device_info = "Linux tun/tap device (tap mode)";
  91         }
  92
  93 #ifdef IFF_ONE_QUEUE
  94         /* Set IFF_ONE_QUEUE flag... */
  95
  96         bool t1q = false;
  97
  98         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q) {
  99                 ifr.ifr_flags |= IFF_ONE_QUEUE;
 100         }
 101
 102 #endif
 103
 104         if(iface) {
 105                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
 106                 ifr.ifr_name[IFNAMSIZ - 1] = 0;
 107         }
 108
 109         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
 110                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 111                 ifrname[IFNAMSIZ - 1] = 0;
 112                 free(iface);
 113                 iface = xstrdup(ifrname);
 114         } else {
 115                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not create a tun/tap interface from %s: %s", device, strerror(errno));
 116                 return false;
 117         }
 118
 119         logger(DEBUG_ALWAYS, LOG_INFO, "%s is a %s", device, device_info);
 120
 121         if(ifr.ifr_flags & IFF_TAP) {
 122                 struct ifreq ifr_mac = {0};
 123
 124                 if(!ioctl(device_fd, SIOCGIFHWADDR, &ifr_mac)) {
 125                         memcpy(mymac.x, ifr_mac.ifr_hwaddr.sa_data, ETH_ALEN);
 126                 } else {
 127                         logger(DEBUG_ALWAYS, LOG_WARNING, "Could not get MAC address of %s: %s", device, strerror(errno));
 128                 }
 129         }
 130
 131         return true;
 132 }
 133
 134 static void close_device(void) {
 135         close(device_fd);
 136         device_fd = -1;
 137
 138         free(type);
 139         type = NULL;
 140         free(device);
 141         device = NULL;
 142         free(iface);
 143         iface = NULL;
 144         device_info = NULL;
 145 }
 146
 147 static bool read_packet(vpn_packet_t *packet) {
 148         int inlen;
 149
 150         switch(device_type) {
 151         case DEVICE_TYPE_TUN:
 152                 inlen = read(device_fd, DATA(packet) + 10, MTU - 10);
 153
 154                 if(inlen <= 0) {
 155                         logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
 156                                device_info, device, strerror(errno));
 157
 158                         if(errno == EBADFD) {  /* File descriptor in bad state */
 159                                 event_exit();
 160                         }
 161
 162                         return false;
 163                 }
 164
 165                 memset(DATA(packet), 0, 12);
 166                 packet->len = inlen + 10;
 167                 break;
 168
 169         case DEVICE_TYPE_TAP:
 170                 inlen = read(device_fd, DATA(packet), MTU);
 171
 172                 if(inlen <= 0) {
 173                         logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
 174                                device_info, device, strerror(errno));
 175                         return false;
 176                 }
 177
 178                 packet->len = inlen;
 179                 break;
 180
 181         default:
 182                 abort();
 183         }
 184
 185         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 186                device_info);
 187
 188         return true;
 189 }
 190
 191 static bool write_packet(vpn_packet_t *packet) {
 192         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Writing packet of %d bytes to %s",
 193                packet->len, device_info);
 194
 195         switch(device_type) {
 196         case DEVICE_TYPE_TUN:
 197                 DATA(packet)[10] = DATA(packet)[11] = 0;
 198
 199                 if(write(device_fd, DATA(packet) + 10, packet->len - 10) < 0) {
 200                         logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 201                                strerror(errno));
 202                         return false;
 203                 }
 204
 205                 break;
 206
 207         case DEVICE_TYPE_TAP:
 208                 if(write(device_fd, DATA(packet), packet->len) < 0) {
 209                         logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 210                                strerror(errno));
 211                         return false;
 212                 }
 213
 214                 break;
 215
 216         default:
 217                 abort();
 218         }
 219
 220         return true;
 221 }
 222
 223 const devops_t os_devops = {
 224         .setup = setup_device,
 225         .close = close_device,
 226         .read = read_packet,
 227         .write = write_packet,
 228 };