networking/tunctl.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * tun devices controller
   4  *
   5  * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
   6  *
   7  * Original code:
   8  *      Jeff Dike
   9  *
  10  * Licensed under GPLv2, see file LICENSE in this source tree.
  11  */
  12
  13 //usage:#define tunctl_trivial_usage
  14 //usage:       "[-f device] ([-t name] | -d name)" IF_FEATURE_TUNCTL_UG(" [-u owner] [-g group] [-b]")
  15 //usage:#define tunctl_full_usage "\n\n"
  16 //usage:       "Create or delete tun interfaces\n"
  17 //usage:     "\n        -f name         tun device (/dev/net/tun)"
  18 //usage:     "\n        -t name         Create iface 'name'"
  19 //usage:     "\n        -d name         Delete iface 'name'"
  20 //usage:        IF_FEATURE_TUNCTL_UG(
  21 //usage:     "\n        -u owner        Set iface owner"
  22 //usage:     "\n        -g group        Set iface group"
  23 //usage:     "\n        -b              Brief output"
  24 //usage:        )
  25 //usage:
  26 //usage:#define tunctl_example_usage
  27 //usage:       "# tunctl\n"
  28 //usage:       "# tunctl -d tun0\n"
  29
  30 #include <netinet/in.h>
  31 #include <net/if.h>
  32 #include <linux/if_tun.h>
  33 #include "libbb.h"
  34
  35 /* TUNSETGROUP appeared in 2.6.23 */
  36 #ifndef TUNSETGROUP
  37 #define TUNSETGROUP _IOW('T', 206, int)
  38 #endif
  39
  40 #define IOCTL(a, b, c) ioctl_or_perror_and_die(a, b, c, NULL)
  41
  42 #if 1
  43
  44 int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  45 int tunctl_main(int argc UNUSED_PARAM, char **argv)
  46 {
  47         struct ifreq ifr;
  48         int fd;
  49         const char *opt_name = "tap%d";
  50         const char *opt_device = "/dev/net/tun";
  51 #if ENABLE_FEATURE_TUNCTL_UG
  52         const char *opt_user, *opt_group;
  53         long user = -1, group = -1;
  54 #endif
  55         unsigned opts;
  56
  57         enum {
  58                 OPT_f = 1 << 0, // control device name (/dev/net/tun)
  59                 OPT_t = 1 << 1, // create named interface
  60                 OPT_d = 1 << 2, // delete named interface
  61 #if ENABLE_FEATURE_TUNCTL_UG
  62                 OPT_u = 1 << 3, // set new interface owner
  63                 OPT_g = 1 << 4, // set new interface group
  64                 OPT_b = 1 << 5, // brief output
  65 #endif
  66         };
  67
  68         opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
  69         opts = getopt32(argv, "f:t:d:" IF_FEATURE_TUNCTL_UG("u:g:b"),
  70                         &opt_device, &opt_name, &opt_name
  71                         IF_FEATURE_TUNCTL_UG(, &opt_user, &opt_group));
  72
  73         // select device
  74         memset(&ifr, 0, sizeof(ifr));
  75         ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  76         strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
  77
  78         // open device
  79         fd = xopen(opt_device, O_RDWR);
  80         IOCTL(fd, TUNSETIFF, (void *)&ifr);
  81
  82         // delete?
  83         if (opts & OPT_d) {
  84                 IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)0);
  85                 bb_info_msg("Set '%s' %spersistent", ifr.ifr_name, "non");
  86                 return EXIT_SUCCESS;
  87         }
  88
  89         // create
  90 #if ENABLE_FEATURE_TUNCTL_UG
  91         if (opts & OPT_g) {
  92                 group = xgroup2gid(opt_group);
  93                 IOCTL(fd, TUNSETGROUP, (void *)(uintptr_t)group);
  94         } else
  95                 user = geteuid();
  96         if (opts & OPT_u)
  97                 user = xuname2uid(opt_user);
  98         IOCTL(fd, TUNSETOWNER, (void *)(uintptr_t)user);
  99 #endif
 100         IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)1);
 101
 102         // show info
 103 #if ENABLE_FEATURE_TUNCTL_UG
 104         if (opts & OPT_b) {
 105                 puts(ifr.ifr_name);
 106         } else {
 107                 printf("Set '%s' %spersistent", ifr.ifr_name, "");
 108                 printf(" and owned by uid %ld", user);
 109                 if (group != -1)
 110                         printf(" gid %ld", group);
 111                 bb_putchar('\n');
 112         }
 113 #else
 114         puts(ifr.ifr_name);
 115 #endif
 116         return EXIT_SUCCESS;
 117 }
 118
 119 #else
 120
 121 /* -210 bytes: */
 122
 123 int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 124 int tunctl_main(int argc UNUSED_PARAM, char **argv)
 125 {
 126         struct ifreq ifr;
 127         int fd;
 128         const char *opt_name = "tap%d";
 129         const char *opt_device = "/dev/net/tun";
 130         unsigned opts;
 131
 132         enum {
 133                 OPT_f = 1 << 0, // control device name (/dev/net/tun)
 134                 OPT_t = 1 << 1, // create named interface
 135                 OPT_d = 1 << 2, // delete named interface
 136         };
 137
 138         opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
 139         opts = getopt32(argv, "f:t:d:u:g:b", // u, g, b accepted and ignored
 140                         &opt_device, &opt_name, &opt_name, NULL, NULL);
 141
 142         // set interface name
 143         memset(&ifr, 0, sizeof(ifr));
 144         ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
 145         strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
 146
 147         // open device
 148         fd = xopen(opt_device, O_RDWR);
 149         IOCTL(fd, TUNSETIFF, (void *)&ifr);
 150
 151         // create or delete interface
 152         IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)(0 == (opts & OPT_d)));
 153
 154         return EXIT_SUCCESS;
 155 }
 156
 157 #endif