openbsd-compat/port-tun.c

   1 /*
   2  * Copyright (c) 2005 Reyk Floeter <reyk@openbsd.org>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include "includes.h"
  18
  19 #include <sys/types.h>
  20 #include <sys/ioctl.h>
  21
  22 #include <netinet/in.h>
  23 #include <arpa/inet.h>
  24 #include <netinet/ip.h>
  25
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <stdarg.h>
  29 #include <string.h>
  30 #include <unistd.h>
  31
  32 #include "openbsd-compat/sys-queue.h"
  33 #include "log.h"
  34 #include "misc.h"
  35 #include "buffer.h"
  36 #include "channels.h"
  37
  38 /*
  39  * This is the portable version of the SSH tunnel forwarding, it
  40  * uses some preprocessor definitions for various platform-specific
  41  * settings.
  42  *
  43  * SSH_TUN_LINUX        Use the (newer) Linux tun/tap device
  44  * SSH_TUN_FREEBSD      Use the FreeBSD tun/tap device
  45  * SSH_TUN_COMPAT_AF    Translate the OpenBSD address family
  46  * SSH_TUN_PREPEND_AF   Prepend/remove the address family
  47  */
  48
  49 /*
  50  * System-specific tunnel open function
  51  */
  52
  53 #if defined(SSH_TUN_LINUX)
  54 #include <linux/if.h>
  55 #include <linux/if_tun.h>
  56
  57 int
  58 sys_tun_open(int tun, int mode)
  59 {
  60         struct ifreq ifr;
  61         int fd = -1;
  62         const char *name = NULL;
  63
  64         if ((fd = open("/dev/net/tun", O_RDWR)) == -1) {
  65                 debug("%s: failed to open tunnel control interface: %s",
  66                     __func__, strerror(errno));
  67                 return (-1);
  68         }
  69
  70         bzero(&ifr, sizeof(ifr));
  71
  72         if (mode == SSH_TUNMODE_ETHERNET) {
  73                 ifr.ifr_flags = IFF_TAP;
  74                 name = "tap%d";
  75         } else {
  76                 ifr.ifr_flags = IFF_TUN;
  77                 name = "tun%d";
  78         }
  79         ifr.ifr_flags |= IFF_NO_PI;
  80
  81         if (tun != SSH_TUNID_ANY) {
  82                 if (tun > SSH_TUNID_MAX) {
  83                         debug("%s: invalid tunnel id %x: %s", __func__,
  84                             tun, strerror(errno));
  85                         goto failed;
  86                 }
  87                 snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun);
  88         }
  89
  90         if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
  91                 debug("%s: failed to configure tunnel (mode %d): %s", __func__,
  92                     mode, strerror(errno));
  93                 goto failed;
  94         }
  95
  96         if (tun == SSH_TUNID_ANY)
  97                 debug("%s: tunnel mode %d fd %d", __func__, mode, fd);
  98         else
  99                 debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);
 100
 101         return (fd);
 102
 103  failed:
 104         close(fd);
 105         return (-1);
 106 }
 107 #endif /* SSH_TUN_LINUX */
 108
 109 #ifdef SSH_TUN_FREEBSD
 110 #include <sys/socket.h>
 111 #include <net/if.h>
 112
 113 #ifdef HAVE_NET_IF_TUN_H
 114 #include <net/if_tun.h>
 115 #endif
 116
 117 int
 118 sys_tun_open(int tun, int mode)
 119 {
 120         struct ifreq ifr;
 121         char name[100];
 122         int fd = -1, sock, flag;
 123         const char *tunbase = "tun";
 124
 125         if (mode == SSH_TUNMODE_ETHERNET) {
 126 #ifdef SSH_TUN_NO_L2
 127                 debug("%s: no layer 2 tunnelling support", __func__);
 128                 return (-1);
 129 #else
 130                 tunbase = "tap";
 131 #endif
 132         }
 133
 134         /* Open the tunnel device */
 135         if (tun <= SSH_TUNID_MAX) {
 136                 snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
 137                 fd = open(name, O_RDWR);
 138         } else if (tun == SSH_TUNID_ANY) {
 139                 for (tun = 100; tun >= 0; tun--) {
 140                         snprintf(name, sizeof(name), "/dev/%s%d",
 141                             tunbase, tun);
 142                         if ((fd = open(name, O_RDWR)) >= 0)
 143                                 break;
 144                 }
 145         } else {
 146                 debug("%s: invalid tunnel %u\n", __func__, tun);
 147                 return (-1);
 148         }
 149
 150         if (fd < 0) {
 151                 debug("%s: %s open failed: %s", __func__, name,
 152                     strerror(errno));
 153                 return (-1);
 154         }
 155
 156         /* Turn on tunnel headers */
 157         flag = 1;
 158 #if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
 159         if (mode != SSH_TUNMODE_ETHERNET &&
 160             ioctl(fd, TUNSIFHEAD, &flag) == -1) {
 161                 debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd,
 162                     strerror(errno));
 163                 close(fd);
 164         }
 165 #endif
 166
 167         debug("%s: %s mode %d fd %d", __func__, name, mode, fd);
 168
 169         /* Set the tunnel device operation mode */
 170         snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
 171         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
 172                 goto failed;
 173
 174         if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
 175                 goto failed;
 176         if ((ifr.ifr_flags & IFF_UP) == 0) {
 177                 ifr.ifr_flags |= IFF_UP;
 178                 if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
 179                         goto failed;
 180         }
 181
 182         close(sock);
 183         return (fd);
 184
 185  failed:
 186         if (fd >= 0)
 187                 close(fd);
 188         if (sock >= 0)
 189                 close(sock);
 190         debug("%s: failed to set %s mode %d: %s", __func__, name,
 191             mode, strerror(errno));
 192         return (-1);
 193 }
 194 #endif /* SSH_TUN_FREEBSD */
 195
 196 /*
 197  * System-specific channel filters
 198  */
 199
 200 #if defined(SSH_TUN_FILTER)
 201 #define OPENBSD_AF_INET         2
 202 #define OPENBSD_AF_INET6        24
 203
 204 int
 205 sys_tun_infilter(struct Channel *c, char *buf, int len)
 206 {
 207 #if defined(SSH_TUN_PREPEND_AF)
 208         char rbuf[CHAN_RBUF];
 209         struct ip *iph;
 210 #endif
 211         u_int32_t *af;
 212         char *ptr = buf;
 213
 214 #if defined(SSH_TUN_PREPEND_AF)
 215         if (len <= 0 || len > (int)(sizeof(rbuf) - sizeof(*af)))
 216                 return (-1);
 217         ptr = (char *)&rbuf[0];
 218         bcopy(buf, ptr + sizeof(u_int32_t), len);
 219         len += sizeof(u_int32_t);
 220         af = (u_int32_t *)ptr;
 221
 222         iph = (struct ip *)(ptr + sizeof(u_int32_t));
 223         switch (iph->ip_v) {
 224         case 6:
 225                 *af = AF_INET6;
 226                 break;
 227         case 4:
 228         default:
 229                 *af = AF_INET;
 230                 break;
 231         }
 232 #endif
 233
 234 #if defined(SSH_TUN_COMPAT_AF)
 235         if (len < (int)sizeof(u_int32_t))
 236                 return (-1);
 237
 238         af = (u_int32_t *)ptr;
 239         if (*af == htonl(AF_INET6))
 240                 *af = htonl(OPENBSD_AF_INET6);
 241         else
 242                 *af = htonl(OPENBSD_AF_INET);
 243 #endif
 244
 245         buffer_put_string(&c->input, ptr, len);
 246         return (0);
 247 }
 248
 249 u_char *
 250 sys_tun_outfilter(struct Channel *c, u_char **data, u_int *dlen)
 251 {
 252         u_char *buf;
 253         u_int32_t *af;
 254
 255         *data = buffer_get_string(&c->output, dlen);
 256         if (*dlen < sizeof(*af))
 257                 return (NULL);
 258         buf = *data;
 259
 260 #if defined(SSH_TUN_PREPEND_AF)
 261         *dlen -= sizeof(u_int32_t);
 262         buf = *data + sizeof(u_int32_t);
 263 #elif defined(SSH_TUN_COMPAT_AF)
 264         af = ntohl(*(u_int32_t *)buf);
 265         if (*af == OPENBSD_AF_INET6)
 266                 *af = htonl(AF_INET6);
 267         else
 268                 *af = htonl(AF_INET);
 269 #endif
 270
 271         return (buf);
 272 }
 273 #endif /* SSH_TUN_FILTER */