mdw@git.distorted.org.uk Git - tripe/blob - server/tun-linux.c

   1 /* -*-c-*-
   2  *
   3  * Tunnel interface based on Linux TUN/TAP driver
   4  *
   5  * (c) 2003 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #define TUN_INTERNALS
  30
  31 #include "tripe.h"
  32
  33 #ifdef TUN_LINUX
  34 #  include <sys/ioctl.h>
  35 #  include <linux/if.h>
  36 #  include <linux/if_tun.h>
  37 #endif
  38
  39 /*----- Main code ---------------------------------------------------------*/
  40
  41 #ifdef TUN_LINUX
  42
  43 struct tunnel {
  44   const tunnel_ops *ops;                /* Pointer to operations */
  45   sel_file f;                           /* Selector for TUN/TAP device */
  46   struct peer *p;                       /* Pointer to my peer */
  47 };
  48
  49 /* --- @t_read@ --- *
  50  *
  51  * Arguments:   @int fd@ = file descriptor to read
  52  *              @unsigned mode@ = what's happened
  53  *              @void *v@ = pointer to tunnel block
  54  *
  55  * Returns:     ---
  56  *
  57  * Use:         Reads data from the tunnel.
  58  */
  59
  60 static void t_read(int fd, unsigned mode, void *v)
  61 {
  62   tunnel *t = v;
  63   ssize_t n;
  64   buf b;
  65
  66   n = read(fd, buf_i, sizeof(buf_i));
  67   if (n < 0) {
  68     a_warn("TUN", "%s", p_ifname(t->p), "read-error", "?ERRNO", A_END);
  69     return;
  70   }
  71   IF_TRACING(T_TUNNEL, {
  72     trace(T_TUNNEL, "tun-linux: packet arrived");
  73     trace_block(T_PACKET, "tun-linux: packet contents", buf_i, n);
  74   })
  75   buf_init(&b, buf_i, n);
  76   p_tun(t->p, &b);
  77 }
  78
  79 /* --- @t_init@ --- *
  80  *
  81  * Arguments:   ---
  82  *
  83  * Returns:     ---
  84  *
  85  * Use:         Initializes the tunneling system.  Maybe this will require
  86  *              opening file descriptors or something.
  87  */
  88
  89 static void t_init(void) { return; }
  90
  91 /* --- @t_open@ --- *
  92  *
  93  * Arguments:   @char **ifn@ = where to put the interface name
  94  *
  95  * Returns:     A file descriptor, or @-1@ on failure.
  96  *
  97  * Use:         Opens a tunnel device.  This will run with root privileges
  98  *              even if the rest of the server has dropped them.
  99  */
 100
 101 static int t_open(char **ifn)
 102 {
 103   int fd;
 104   struct ifreq iff;
 105
 106   if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
 107     a_warn("TUN", "-", "linux",
 108            "open-error", "/dev/net/tun", "?ERRNO",
 109            A_END);
 110     return (-1);
 111   }
 112   memset(&iff, 0, sizeof(iff));
 113   iff.ifr_name[0] = 0;
 114   iff.ifr_flags = IFF_TUN | IFF_NO_PI;
 115   if (ioctl(fd, TUNSETIFF, &iff) < 0) {
 116     a_warn("TUN", "-", "linux", "config-error", "?ERRNO", A_END);
 117     close(fd);
 118     return (-1);
 119   }
 120   iff.ifr_name[IFNAMSIZ - 1] = 0;
 121   *ifn = xstrdup(iff.ifr_name);
 122   return (fd);
 123 }
 124
 125 /* --- @t_create@ --- *
 126  *
 127  * Arguments:   @peer *p@ = pointer to peer block
 128  *              @int fd@ = file descriptor of tunnel device
 129  *              @char **ifn@ = where to put the interface name
 130  *
 131  * Returns:     A tunnel block if it worked, or null on failure.
 132  *
 133  * Use:         Initializes a new tunnel.
 134  */
 135
 136 static tunnel *t_create(peer *p, int fd, char **ifn)
 137 {
 138   tunnel *t;
 139
 140   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 141   t = CREATE(tunnel);
 142   t->ops = &tun_linux;
 143   t->p = p;
 144   sel_initfile(&sel, &t->f, fd, SEL_READ, t_read, t);
 145   sel_addfile(&t->f);
 146   return (t);
 147 }
 148
 149 /* --- @t_inject@ --- *
 150  *
 151  * Arguments:   @tunnel *t@ = pointer to tunnel block
 152  *              @buf *b@ = buffer to send
 153  *
 154  * Returns:     ---
 155  *
 156  * Use:         Injects a packet into the local network stack.
 157  */
 158
 159 static void t_inject(tunnel *t, buf *b)
 160 {
 161   IF_TRACING(T_TUNNEL, {
 162     trace(T_TUNNEL, "tun-linux: inject decrypted packet");
 163     trace_block(T_PACKET, "tunnel: packet contents", BBASE(b), BLEN(b));
 164   })
 165   write(t->f.fd, BBASE(b), BLEN(b));
 166 }
 167
 168 /* --- @t_destroy@ --- *
 169  *
 170  * Arguments:   @tunnel *t@ = pointer to tunnel block
 171  *
 172  * Returns:     ---
 173  *
 174  * Use:         Destroys a tunnel.
 175  */
 176
 177 static void t_destroy(tunnel *t)
 178   { sel_rmfile(&t->f); close(t->f.fd); DESTROY(t); }
 179
 180 const tunnel_ops tun_linux = {
 181   "linux",
 182   t_init,
 183   t_open,
 184   t_create,
 185   0,
 186   t_inject,
 187   t_destroy
 188 };
 189
 190 #endif
 191
 192 /*----- That's all, folks -------------------------------------------------*/