crypto/openssh-5/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 "log.h"
  33 #include "misc.h"
  34 #include "buffer.h"
  35 #include "channels.h"
  36
  37 /*
  38  * This is the portable version of the SSH tunnel forwarding, it
  39  * uses some preprocessor definitions for various platform-specific
  40  * settings.
  41  *
  42  * SSH_TUN_LINUX        Use the (newer) Linux tun/tap device
  43  * SSH_TUN_FREEBSD      Use the FreeBSD tun/tap device
  44  * SSH_TUN_COMPAT_AF    Translate the OpenBSD address family
  45  * SSH_TUN_PREPEND_AF   Prepend/remove the address family
  46  */
  47
  48 /*
  49  * System-specific tunnel open function
  50  */
  51
  52 #if defined(SSH_TUN_LINUX)
  53 #include <linux/if.h>
  54 #include <linux/if_tun.h>
  55
  56 int
  57 sys_tun_open(int tun, int mode)
  58 {
  59         struct ifreq ifr;
  60         int fd = -1;
  61         const char *name = NULL;
  62
  63         if ((fd = open("/dev/net/tun", O_RDWR)) == -1) {
  64                 debug("%s: failed to open tunnel control interface: %s",
  65                     __func__, strerror(errno));
  66                 return (-1);
  67         }
  68
  69         bzero(&ifr, sizeof(ifr));
  70
  71         if (mode == SSH_TUNMODE_ETHERNET) {
  72                 ifr.ifr_flags = IFF_TAP;
  73                 name = "tap%d";
  74         } else {
  75                 ifr.ifr_flags = IFF_TUN;
  76                 name = "tun%d";
  77         }
  78         ifr.ifr_flags |= IFF_NO_PI;
  79
  80         if (tun != SSH_TUNID_ANY) {
  81                 if (tun > SSH_TUNID_MAX) {
  82                         debug("%s: invalid tunnel id %x: %s", __func__,
  83                             tun, strerror(errno));
  84                         goto failed;
  85                 }
  86                 snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun);
  87         }
  88
  89         if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
  90                 debug("%s: failed to configure tunnel (mode %d): %s", __func__,
  91                     mode, strerror(errno));
  92                 goto failed;
  93         }
  94
  95         if (tun == SSH_TUNID_ANY)
  96                 debug("%s: tunnel mode %d fd %d", __func__, mode, fd);
  97         else
  98                 debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);
  99
 100         return (fd);
 101
 102  failed:
 103         close(fd);
 104         return (-1);
 105 }
 106 #endif /* SSH_TUN_LINUX */
 107
 108 #ifdef SSH_TUN_FREEBSD
 109 #include <sys/socket.h>
 110 #include <net/if.h>
 111
 112 #ifdef HAVE_NET_IF_TUN_H
 113 #include <net/tun/if_tun.h>
 114 #endif
 115
 116 int
 117 sys_tun_open(int tun, int mode)
 118 {
 119         struct ifreq ifr;
 120         char name[100];
 121         int fd = -1, sock, flag;
 122         const char *tunbase = "tun";
 123
 124         if (mode == SSH_TUNMODE_ETHERNET) {
 125 #ifdef SSH_TUN_NO_L2
 126                 debug("%s: no layer 2 tunnelling support", __func__);
 127                 return (-1);
 128 #else
 129                 tunbase = "tap";
 130 #endif
 131         }
 132
 133         /* Open the tunnel device */
 134         if (tun <= SSH_TUNID_MAX) {
 135                 snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
 136                 fd = open(name, O_RDWR);
 137         } else if (tun == SSH_TUNID_ANY) {
 138                 for (tun = 100; tun >= 0; tun--) {
 139                         snprintf(name, sizeof(name), "/dev/%s%d",
 140                             tunbase, tun);
 141                         if ((fd = open(name, O_RDWR)) >= 0)
 142                                 break;
 143                 }
 144         } else {
 145                 debug("%s: invalid tunnel %u\n", __func__, tun);
 146                 return (-1);
 147         }
 148
 149         if (fd < 0) {
 150                 debug("%s: %s open failed: %s", __func__, name,
 151                     strerror(errno));
 152                 return (-1);
 153         }
 154
 155         /* Turn on tunnel headers */
 156         flag = 1;
 157 #if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
 158         if (mode != SSH_TUNMODE_ETHERNET &&
 159             ioctl(fd, TUNSIFHEAD, &flag) == -1) {
 160                 debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd,
 161                     strerror(errno));
 162                 close(fd);
 163         }
 164 #endif
 165
 166         debug("%s: %s mode %d fd %d", __func__, name, mode, fd);
 167
 168         /* Set the tunnel device operation mode */
 169         snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
 170         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
 171                 goto failed;
 172
 173         if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
 174                 goto failed;
 175         ifr.ifr_flags |= IFF_UP;
 176         if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
 177                 goto failed;
 178
 179         close(sock);
 180         return (fd);
 181
 182  failed:
 183         if (fd >= 0)
 184                 close(fd);
 185         if (sock >= 0)
 186                 close(sock);
 187         debug("%s: failed to set %s mode %d: %s", __func__, name,
 188             mode, strerror(errno));
 189         return (-1);
 190 }
 191 #endif /* SSH_TUN_FREEBSD */
 192
 193 /*
 194  * System-specific channel filters
 195  */
 196
 197 #if defined(SSH_TUN_FILTER)
 198 #define OPENBSD_AF_INET         2
 199 #define OPENBSD_AF_INET6        24
 200
 201 int
 202 sys_tun_infilter(struct Channel *c, char *buf, int len)
 203 {
 204 #if defined(SSH_TUN_PREPEND_AF)
 205         char rbuf[CHAN_RBUF];
 206         struct ip *iph;
 207 #endif
 208         u_int32_t *af;
 209         char *ptr = buf;
 210
 211 #if defined(SSH_TUN_PREPEND_AF)
 212         if (len <= 0 || len > (int)(sizeof(rbuf) - sizeof(*af)))
 213                 return (-1);
 214         ptr = (char *)&rbuf[0];
 215         bcopy(buf, ptr + sizeof(u_int32_t), len);
 216         len += sizeof(u_int32_t);
 217         af = (u_int32_t *)ptr;
 218
 219         iph = (struct ip *)(ptr + sizeof(u_int32_t));
 220         switch (iph->ip_v) {
 221         case 6:
 222                 *af = AF_INET6;
 223                 break;
 224         case 4:
 225         default:
 226                 *af = AF_INET;
 227                 break;
 228         }
 229 #endif
 230
 231 #if defined(SSH_TUN_COMPAT_AF)
 232         if (len < (int)sizeof(u_int32_t))
 233                 return (-1);
 234
 235         af = (u_int32_t *)ptr;
 236         if (*af == htonl(AF_INET6))
 237                 *af = htonl(OPENBSD_AF_INET6);
 238         else
 239                 *af = htonl(OPENBSD_AF_INET);
 240 #endif
 241
 242         buffer_put_string(&c->input, ptr, len);
 243         return (0);
 244 }
 245
 246 u_char *
 247 sys_tun_outfilter(struct Channel *c, u_char **data, u_int *dlen)
 248 {
 249         u_char *buf;
 250         u_int32_t *af;
 251
 252         *data = buffer_get_string(&c->output, dlen);
 253         if (*dlen < sizeof(*af))
 254                 return (NULL);
 255         buf = *data;
 256
 257 #if defined(SSH_TUN_PREPEND_AF)
 258         *dlen -= sizeof(u_int32_t);
 259         buf = *data + sizeof(u_int32_t);
 260 #elif defined(SSH_TUN_COMPAT_AF)
 261         af = ntohl(*(u_int32_t *)buf);
 262         if (*af == OPENBSD_AF_INET6)
 263                 *af = htonl(AF_INET6);
 264         else
 265                 *af = htonl(AF_INET);
 266 #endif
 267
 268         return (buf);
 269 }
 270 #endif /* SSH_TUN_FILTER */