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