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 <fcntl.h>
  22 #include <linux/if_tun.h>
  23 #include <net/if.h>
  24 #include <netinet/if_ether.h>
  25 #include <sys/ioctl.h>
  26 #include <sys/stat.h>
  27 #include <sys/types.h>
  28
  29 #include "alloc-util.h"
  30 #include "fd-util.h"
  31 #include "netdev/tuntap.h"
  32 #include "user-util.h"
  33
  34 #define TUN_DEV "/dev/net/tun"
  35
  36 static int netdev_fill_tuntap_message(NetDev *netdev, struct ifreq *ifr) {
  37         TunTap *t;
  38
  39         assert(netdev);
  40         assert(netdev->ifname);
  41         assert(ifr);
  42
  43         if (netdev->kind == NETDEV_KIND_TAP) {
  44                 t = TAP(netdev);
  45                 ifr->ifr_flags |= IFF_TAP;
  46         } else {
  47                 t = TUN(netdev);
  48                 ifr->ifr_flags |= IFF_TUN;
  49         }
  50
  51         if (!t->packet_info)
  52                 ifr->ifr_flags |= IFF_NO_PI;
  53
  54         if (t->one_queue)
  55                 ifr->ifr_flags |= IFF_ONE_QUEUE;
  56
  57         if (t->multi_queue)
  58                 ifr->ifr_flags |= IFF_MULTI_QUEUE;
  59
  60         if (t->vnet_hdr)
  61                 ifr->ifr_flags |= IFF_VNET_HDR;
  62
  63         strncpy(ifr->ifr_name, netdev->ifname, IFNAMSIZ-1);
  64
  65         return 0;
  66 }
  67
  68 static int netdev_tuntap_add(NetDev *netdev, struct ifreq *ifr) {
  69         _cleanup_close_ int fd;
  70         TunTap *t = NULL;
  71         const char *user;
  72         const char *group;
  73         uid_t uid;
  74         gid_t gid;
  75         int r;
  76
  77         assert(netdev);
  78         assert(ifr);
  79
  80         fd = open(TUN_DEV, O_RDWR);
  81         if (fd < 0)
  82                 return log_netdev_error_errno(netdev, -errno,  "Failed to open tun dev: %m");
  83
  84         r = ioctl(fd, TUNSETIFF, ifr);
  85         if (r < 0)
  86                 return log_netdev_error_errno(netdev, -errno, "TUNSETIFF failed on tun dev: %m");
  87
  88         if (netdev->kind == NETDEV_KIND_TAP)
  89                 t = TAP(netdev);
  90         else
  91                 t = TUN(netdev);
  92
  93         assert(t);
  94
  95         if (t->user_name) {
  96
  97                 user = t->user_name;
  98
  99                 r = get_user_creds(&user, &uid, NULL, NULL, NULL);
 100                 if (r < 0)
 101                         return log_netdev_error_errno(netdev, r, "Cannot resolve user name %s: %m", t->user_name);
 102
 103                 r = ioctl(fd, TUNSETOWNER, uid);
 104                 if (r < 0)
 105                         return log_netdev_error_errno(netdev, -errno, "TUNSETOWNER failed on tun dev: %m");
 106         }
 107
 108         if (t->group_name) {
 109
 110                 group = t->group_name;
 111
 112                 r = get_group_creds(&group, &gid);
 113                 if (r < 0)
 114                         return log_netdev_error_errno(netdev, r, "Cannot resolve group name %s: %m", t->group_name);
 115
 116                 r = ioctl(fd, TUNSETGROUP, gid);
 117                 if (r < 0)
 118                         return log_netdev_error_errno(netdev, -errno, "TUNSETGROUP failed on tun dev: %m");
 119
 120         }
 121
 122         r = ioctl(fd, TUNSETPERSIST, 1);
 123         if (r < 0)
 124                 return log_netdev_error_errno(netdev, -errno, "TUNSETPERSIST failed on tun dev: %m");
 125
 126         return 0;
 127 }
 128
 129 static int netdev_create_tuntap(NetDev *netdev) {
 130         struct ifreq ifr = {};
 131         int r;
 132
 133         r = netdev_fill_tuntap_message(netdev, &ifr);
 134         if (r < 0)
 135                 return r;
 136
 137         return netdev_tuntap_add(netdev, &ifr);
 138 }
 139
 140 static void tuntap_done(NetDev *netdev) {
 141         TunTap *t = NULL;
 142
 143         assert(netdev);
 144
 145         if (netdev->kind == NETDEV_KIND_TUN)
 146                 t = TUN(netdev);
 147         else
 148                 t = TAP(netdev);
 149
 150         assert(t);
 151
 152         t->user_name = mfree(t->user_name);
 153         t->group_name = mfree(t->group_name);
 154 }
 155
 156 static int tuntap_verify(NetDev *netdev, const char *filename) {
 157         assert(netdev);
 158
 159         if (netdev->mtu)
 160                 log_netdev_warning(netdev, "MTU configured for %s, ignoring", netdev_kind_to_string(netdev->kind));
 161
 162         if (netdev->mac)
 163                 log_netdev_warning(netdev, "MAC configured for %s, ignoring", netdev_kind_to_string(netdev->kind));
 164
 165         return 0;
 166 }
 167
 168 const NetDevVTable tun_vtable = {
 169         .object_size = sizeof(TunTap),
 170         .sections = "Match\0NetDev\0Tun\0",
 171         .config_verify = tuntap_verify,
 172         .done = tuntap_done,
 173         .create = netdev_create_tuntap,
 174         .create_type = NETDEV_CREATE_INDEPENDENT,
 175 };
 176
 177 const NetDevVTable tap_vtable = {
 178         .object_size = sizeof(TunTap),
 179         .sections = "Match\0NetDev\0Tap\0",
 180         .config_verify = tuntap_verify,
 181         .done = tuntap_done,
 182         .create = netdev_create_tuntap,
 183         .create_type = NETDEV_CREATE_INDEPENDENT,
 184 };