src/linux/device.c

   1 /*
   2     device.c -- Interaction with Linux ethertap and tun/tap device
   3     Copyright (C) 2001-2005 Ivo Timmermans,
   4                   2001-2013 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 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         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  63 #ifdef HAVE_LINUX_IF_TUN_H
  64                 if (netname != NULL)
  65                         iface = xstrdup(netname);
  66 #else
  67                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
  68 #endif
  69         device_fd = open(device, O_RDWR | O_NONBLOCK);
  70
  71         if(device_fd < 0) {
  72                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  73                 return false;
  74         }
  75
  76 #ifdef FD_CLOEXEC
  77         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
  78 #endif
  79
  80 #ifdef HAVE_LINUX_IF_TUN_H
  81         /* Ok now check if this is an old ethertap or a new tun/tap thingie */
  82
  83         memset(&ifr, 0, sizeof(ifr));
  84
  85         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
  86
  87         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
  88                 logger(LOG_ERR, "Unknown device type %s!", type);
  89                 return false;
  90         }
  91
  92         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
  93                 ifr.ifr_flags = IFF_TUN;
  94                 device_type = DEVICE_TYPE_TUN;
  95                 device_info = "Linux tun/tap device (tun mode)";
  96         } else {
  97                 if (routing_mode == RMODE_ROUTER)
  98                         overwrite_mac = true;
  99                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
 100                 device_type = DEVICE_TYPE_TAP;
 101                 device_info = "Linux tun/tap device (tap mode)";
 102         }
 103
 104 #ifdef IFF_ONE_QUEUE
 105         /* Set IFF_ONE_QUEUE flag... */
 106         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q)
 107                 ifr.ifr_flags |= IFF_ONE_QUEUE;
 108 #endif
 109
 110         if(iface)
 111                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
 112
 113         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
 114                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 115                 if(iface) free(iface);
 116                 iface = xstrdup(ifrname);
 117         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
 118                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
 119                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 120                 if(iface) free(iface);
 121                 iface = xstrdup(ifrname);
 122         } else
 123 #endif
 124         {
 125                 if(routing_mode == RMODE_ROUTER)
 126                         overwrite_mac = true;
 127                 device_info = "Linux ethertap device";
 128                 device_type = DEVICE_TYPE_ETHERTAP;
 129                 if(iface)
 130                         free(iface);
 131                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
 132         }
 133
 134         logger(LOG_INFO, "%s is a %s", device, device_info);
 135
 136         return true;
 137 }
 138
 139 static void close_device(void) {
 140         close(device_fd);
 141
 142         free(type);
 143         free(device);
 144         free(iface);
 145 }
 146
 147 static bool read_packet(vpn_packet_t *packet) {
 148         int lenin;
 149
 150         switch(device_type) {
 151                 case DEVICE_TYPE_TUN:
 152                         lenin = read(device_fd, packet->data + 10, MTU - 10);
 153
 154                         if(lenin <= 0) {
 155                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 156                                            device_info, device, strerror(errno));
 157                                 return false;
 158                         }
 159
 160                         memset(packet->data, 0, 12);
 161                         packet->len = lenin + 10;
 162                         break;
 163                 case DEVICE_TYPE_TAP:
 164                         lenin = read(device_fd, packet->data, MTU);
 165
 166                         if(lenin <= 0) {
 167                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 168                                            device_info, device, strerror(errno));
 169                                 return false;
 170                         }
 171
 172                         packet->len = lenin;
 173                         break;
 174                 case DEVICE_TYPE_ETHERTAP:
 175                         lenin = read(device_fd, packet->data - 2, MTU + 2);
 176
 177                         if(lenin <= 0) {
 178                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 179                                            device_info, device, strerror(errno));
 180                                 return false;
 181                         }
 182
 183                         packet->len = lenin - 2;
 184                         break;
 185         }
 186
 187         device_total_in += packet->len;
 188
 189         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 190                            device_info);
 191
 192         return true;
 193 }
 194
 195 static bool write_packet(vpn_packet_t *packet) {
 196         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
 197                            packet->len, device_info);
 198
 199         switch(device_type) {
 200                 case DEVICE_TYPE_TUN:
 201                         packet->data[10] = packet->data[11] = 0;
 202                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
 203                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 204                                            strerror(errno));
 205                                 return false;
 206                         }
 207                         break;
 208                 case DEVICE_TYPE_TAP:
 209                         if(write(device_fd, packet->data, packet->len) < 0) {
 210                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 211                                            strerror(errno));
 212                                 return false;
 213                         }
 214                         break;
 215                 case DEVICE_TYPE_ETHERTAP:
 216                         memcpy(packet->data - 2, &packet->len, 2);
 217
 218                         if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
 219                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 220                                            strerror(errno));
 221                                 return false;
 222                         }
 223                         break;
 224         }
 225
 226         device_total_out += packet->len;
 227
 228         return true;
 229 }
 230
 231 static void dump_device_stats(void) {
 232         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
 233         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_total_in);
 234         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
 235 }
 236
 237 const devops_t os_devops = {
 238         .setup = setup_device,
 239         .close = close_device,
 240         .read = read_packet,
 241         .write = write_packet,
 242         .dump_stats = dump_device_stats,
 243 };