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