src/network/netdev/tuntap.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3     This file is part of systemd.
   4
   5     Copyright 2014 Susant Sahani <susant@redhat.com>
   6
   7     systemd is free software; you can redistribute it and/or modify it
   8     under the terms of the GNU Lesser General Public License as published by
   9     the Free Software Foundation; either version 2.1 of the License, or
  10     (at your option) any later version.
  11
  12     systemd is distributed in the hope that it will be useful, but
  13     WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15     Lesser General Public License for more details.
  16
  17     You should have received a copy of the GNU Lesser General Public License
  18     along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <linux/if_tun.h>
  24 #include <net/if.h>
  25 #include <netinet/if_ether.h>
  26 #include <sys/ioctl.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29
  30 #include "alloc-util.h"
  31 #include "fd-util.h"
  32 #include "netdev/tuntap.h"
  33 #include "user-util.h"
  34
  35 #define TUN_DEV "/dev/net/tun"
  36
  37 static int netdev_fill_tuntap_message(NetDev *netdev, struct ifreq *ifr) {
  38         TunTap *t;
  39
  40         assert(netdev);
  41         assert(netdev->ifname);
  42         assert(ifr);
  43
  44         if (netdev->kind == NETDEV_KIND_TAP) {
  45                 t = TAP(netdev);
  46                 ifr->ifr_flags |= IFF_TAP;
  47         } else {
  48                 t = TUN(netdev);
  49                 ifr->ifr_flags |= IFF_TUN;
  50         }
  51
  52         if (!t->packet_info)
  53                 ifr->ifr_flags |= IFF_NO_PI;
  54
  55         if (t->one_queue)
  56                 ifr->ifr_flags |= IFF_ONE_QUEUE;
  57
  58         if (t->multi_queue)
  59                 ifr->ifr_flags |= IFF_MULTI_QUEUE;
  60
  61         if (t->vnet_hdr)
  62                 ifr->ifr_flags |= IFF_VNET_HDR;
  63
  64         strncpy(ifr->ifr_name, netdev->ifname, IFNAMSIZ-1);
  65
  66         return 0;
  67 }
  68
  69 static int netdev_tuntap_add(NetDev *netdev, struct ifreq *ifr) {
  70         _cleanup_close_ int fd;
  71         TunTap *t = NULL;
  72         const char *user;
  73         const char *group;
  74         uid_t uid;
  75         gid_t gid;
  76         int r;
  77
  78         assert(netdev);
  79         assert(ifr);
  80
  81         fd = open(TUN_DEV, O_RDWR);
  82         if (fd < 0)
  83                 return log_netdev_error_errno(netdev, -errno,  "Failed to open tun dev: %m");
  84
  85         r = ioctl(fd, TUNSETIFF, ifr);
  86         if (r < 0)
  87                 return log_netdev_error_errno(netdev, -errno, "TUNSETIFF failed on tun dev: %m");
  88
  89         if (netdev->kind == NETDEV_KIND_TAP)
  90                 t = TAP(netdev);
  91         else
  92                 t = TUN(netdev);
  93
  94         assert(t);
  95
  96         if (t->user_name) {
  97
  98                 user = t->user_name;
  99
 100                 r = get_user_creds(&user, &uid, NULL, NULL, NULL);
 101                 if (r < 0)
 102                         return log_netdev_error_errno(netdev, r, "Cannot resolve user name %s: %m", t->user_name);
 103
 104                 r = ioctl(fd, TUNSETOWNER, uid);
 105                 if (r < 0)
 106                         return log_netdev_error_errno(netdev, -errno, "TUNSETOWNER failed on tun dev: %m");
 107         }
 108
 109         if (t->group_name) {
 110
 111                 group = t->group_name;
 112
 113                 r = get_group_creds(&group, &gid);
 114                 if (r < 0)
 115                         return log_netdev_error_errno(netdev, r, "Cannot resolve group name %s: %m", t->group_name);
 116
 117                 r = ioctl(fd, TUNSETGROUP, gid);
 118                 if (r < 0)
 119                         return log_netdev_error_errno(netdev, -errno, "TUNSETGROUP failed on tun dev: %m");
 120
 121         }
 122
 123         r = ioctl(fd, TUNSETPERSIST, 1);
 124         if (r < 0)
 125                 return log_netdev_error_errno(netdev, -errno, "TUNSETPERSIST failed on tun dev: %m");
 126
 127         return 0;
 128 }
 129
 130 static int netdev_create_tuntap(NetDev *netdev) {
 131         struct ifreq ifr = {};
 132         int r;
 133
 134         r = netdev_fill_tuntap_message(netdev, &ifr);
 135         if (r < 0)
 136                 return r;
 137
 138         return netdev_tuntap_add(netdev, &ifr);
 139 }
 140
 141 static void tuntap_done(NetDev *netdev) {
 142         TunTap *t = NULL;
 143
 144         assert(netdev);
 145
 146         if (netdev->kind == NETDEV_KIND_TUN)
 147                 t = TUN(netdev);
 148         else
 149                 t = TAP(netdev);
 150
 151         assert(t);
 152
 153         t->user_name = mfree(t->user_name);
 154         t->group_name = mfree(t->group_name);
 155 }
 156
 157 static int tuntap_verify(NetDev *netdev, const char *filename) {
 158         assert(netdev);
 159
 160         if (netdev->mtu)
 161                 log_netdev_warning(netdev, "MTU configured for %s, ignoring", netdev_kind_to_string(netdev->kind));
 162
 163         if (netdev->mac)
 164                 log_netdev_warning(netdev, "MAC configured for %s, ignoring", netdev_kind_to_string(netdev->kind));
 165
 166         return 0;
 167 }
 168
 169 const NetDevVTable tun_vtable = {
 170         .object_size = sizeof(TunTap),
 171         .sections = "Match\0NetDev\0Tun\0",
 172         .config_verify = tuntap_verify,
 173         .done = tuntap_done,
 174         .create = netdev_create_tuntap,
 175         .create_type = NETDEV_CREATE_INDEPENDENT,
 176 };
 177
 178 const NetDevVTable tap_vtable = {
 179         .object_size = sizeof(TunTap),
 180         .sections = "Match\0NetDev\0Tap\0",
 181         .config_verify = tuntap_verify,
 182         .done = tuntap_done,
 183         .create = netdev_create_tuntap,
 184         .create_type = NETDEV_CREATE_INDEPENDENT,
 185 };