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
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <linux/if_tun.h>
  11 #include <net/if.h>
  12 #include <netinet/if_ether.h>
  13 #include <sys/ioctl.h>
  14 #include <sys/stat.h>
  15 #include <sys/types.h>
  16
  17 #include "alloc-util.h"
  18 #include "fd-util.h"
  19 #include "netdev/tuntap.h"
  20 #include "user-util.h"
  21
  22 #define TUN_DEV "/dev/net/tun"
  23
  24 static int netdev_fill_tuntap_message(NetDev *netdev, struct ifreq *ifr) {
  25         TunTap *t;
  26
  27         assert(netdev);
  28         assert(netdev->ifname);
  29         assert(ifr);
  30
  31         if (netdev->kind == NETDEV_KIND_TAP) {
  32                 t = TAP(netdev);
  33                 ifr->ifr_flags |= IFF_TAP;
  34         } else {
  35                 t = TUN(netdev);
  36                 ifr->ifr_flags |= IFF_TUN;
  37         }
  38
  39         if (!t->packet_info)
  40                 ifr->ifr_flags |= IFF_NO_PI;
  41
  42         if (t->one_queue)
  43                 ifr->ifr_flags |= IFF_ONE_QUEUE;
  44
  45         if (t->multi_queue)
  46                 ifr->ifr_flags |= IFF_MULTI_QUEUE;
  47
  48         if (t->vnet_hdr)
  49                 ifr->ifr_flags |= IFF_VNET_HDR;
  50
  51         strncpy(ifr->ifr_name, netdev->ifname, IFNAMSIZ-1);
  52
  53         return 0;
  54 }
  55
  56 static int netdev_tuntap_add(NetDev *netdev, struct ifreq *ifr) {
  57         _cleanup_close_ int fd;
  58         TunTap *t = NULL;
  59         const char *user;
  60         const char *group;
  61         uid_t uid;
  62         gid_t gid;
  63         int r;
  64
  65         assert(netdev);
  66         assert(ifr);
  67
  68         fd = open(TUN_DEV, O_RDWR);
  69         if (fd < 0)
  70                 return log_netdev_error_errno(netdev, -errno,  "Failed to open tun dev: %m");
  71
  72         r = ioctl(fd, TUNSETIFF, ifr);
  73         if (r < 0)
  74                 return log_netdev_error_errno(netdev, -errno, "TUNSETIFF failed on tun dev: %m");
  75
  76         if (netdev->kind == NETDEV_KIND_TAP)
  77                 t = TAP(netdev);
  78         else
  79                 t = TUN(netdev);
  80
  81         assert(t);
  82
  83         if (t->user_name) {
  84
  85                 user = t->user_name;
  86
  87                 r = get_user_creds(&user, &uid, NULL, NULL, NULL);
  88                 if (r < 0)
  89                         return log_netdev_error_errno(netdev, r, "Cannot resolve user name %s: %m", t->user_name);
  90
  91                 r = ioctl(fd, TUNSETOWNER, uid);
  92                 if (r < 0)
  93                         return log_netdev_error_errno(netdev, -errno, "TUNSETOWNER failed on tun dev: %m");
  94         }
  95
  96         if (t->group_name) {
  97
  98                 group = t->group_name;
  99
 100                 r = get_group_creds(&group, &gid);
 101                 if (r < 0)
 102                         return log_netdev_error_errno(netdev, r, "Cannot resolve group name %s: %m", t->group_name);
 103
 104                 r = ioctl(fd, TUNSETGROUP, gid);
 105                 if (r < 0)
 106                         return log_netdev_error_errno(netdev, -errno, "TUNSETGROUP failed on tun dev: %m");
 107
 108         }
 109
 110         r = ioctl(fd, TUNSETPERSIST, 1);
 111         if (r < 0)
 112                 return log_netdev_error_errno(netdev, -errno, "TUNSETPERSIST failed on tun dev: %m");
 113
 114         return 0;
 115 }
 116
 117 static int netdev_create_tuntap(NetDev *netdev) {
 118         struct ifreq ifr = {};
 119         int r;
 120
 121         r = netdev_fill_tuntap_message(netdev, &ifr);
 122         if (r < 0)
 123                 return r;
 124
 125         return netdev_tuntap_add(netdev, &ifr);
 126 }
 127
 128 static void tuntap_done(NetDev *netdev) {
 129         TunTap *t = NULL;
 130
 131         assert(netdev);
 132
 133         if (netdev->kind == NETDEV_KIND_TUN)
 134                 t = TUN(netdev);
 135         else
 136                 t = TAP(netdev);
 137
 138         assert(t);
 139
 140         t->user_name = mfree(t->user_name);
 141         t->group_name = mfree(t->group_name);
 142 }
 143
 144 static int tuntap_verify(NetDev *netdev, const char *filename) {
 145         assert(netdev);
 146
 147         if (netdev->mtu)
 148                 log_netdev_warning(netdev, "MTU configured for %s, ignoring", netdev_kind_to_string(netdev->kind));
 149
 150         if (netdev->mac)
 151                 log_netdev_warning(netdev, "MAC configured for %s, ignoring", netdev_kind_to_string(netdev->kind));
 152
 153         return 0;
 154 }
 155
 156 const NetDevVTable tun_vtable = {
 157         .object_size = sizeof(TunTap),
 158         .sections = "Match\0NetDev\0Tun\0",
 159         .config_verify = tuntap_verify,
 160         .done = tuntap_done,
 161         .create = netdev_create_tuntap,
 162         .create_type = NETDEV_CREATE_INDEPENDENT,
 163 };
 164
 165 const NetDevVTable tap_vtable = {
 166         .object_size = sizeof(TunTap),
 167         .sections = "Match\0NetDev\0Tap\0",
 168         .config_verify = tuntap_verify,
 169         .done = tuntap_done,
 170         .create = netdev_create_tuntap,
 171         .create_type = NETDEV_CREATE_INDEPENDENT,
 172 };