crypto/openssh/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 "sshbuf.h"
  36 #include "channels.h"
  37 #include "ssherr.h"
  38
  39 /*
  40  * This is the portable version of the SSH tunnel forwarding, it
  41  * uses some preprocessor definitions for various platform-specific
  42  * settings.
  43  *
  44  * SSH_TUN_LINUX        Use the (newer) Linux tun/tap device
  45  * SSH_TUN_FREEBSD      Use the FreeBSD tun/tap device
  46  * SSH_TUN_COMPAT_AF    Translate the OpenBSD address family
  47  * SSH_TUN_PREPEND_AF   Prepend/remove the address family
  48  */
  49
  50 /*
  51  * System-specific tunnel open function
  52  */
  53
  54 #if defined(SSH_TUN_LINUX)
  55 #include <linux/if.h>
  56 #include <linux/if_tun.h>
  57
  58 int
  59 sys_tun_open(int tun, int mode)
  60 {
  61         struct ifreq ifr;
  62         int fd = -1;
  63         const char *name = NULL;
  64
  65         if ((fd = open("/dev/net/tun", O_RDWR)) == -1) {
  66                 debug("%s: failed to open tunnel control interface: %s",
  67                     __func__, strerror(errno));
  68                 return (-1);
  69         }
  70
  71         bzero(&ifr, sizeof(ifr));
  72
  73         if (mode == SSH_TUNMODE_ETHERNET) {
  74                 ifr.ifr_flags = IFF_TAP;
  75                 name = "tap%d";
  76         } else {
  77                 ifr.ifr_flags = IFF_TUN;
  78                 name = "tun%d";
  79         }
  80         ifr.ifr_flags |= IFF_NO_PI;
  81
  82         if (tun != SSH_TUNID_ANY) {
  83                 if (tun > SSH_TUNID_MAX) {
  84                         debug("%s: invalid tunnel id %x: %s", __func__,
  85                             tun, strerror(errno));
  86                         goto failed;
  87                 }
  88                 snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun);
  89         }
  90
  91         if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
  92                 debug("%s: failed to configure tunnel (mode %d): %s", __func__,
  93                     mode, strerror(errno));
  94                 goto failed;
  95         }
  96
  97         if (tun == SSH_TUNID_ANY)
  98                 debug("%s: tunnel mode %d fd %d", __func__, mode, fd);
  99         else
 100                 debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);
 101
 102         return (fd);
 103
 104  failed:
 105         close(fd);
 106         return (-1);
 107 }
 108 #endif /* SSH_TUN_LINUX */
 109
 110 #ifdef SSH_TUN_FREEBSD
 111 #include <sys/socket.h>
 112 #include <net/if.h>
 113
 114 #ifdef HAVE_NET_IF_TUN_H
 115 #include <net/tun/if_tun.h>
 116 #endif
 117
 118 int
 119 sys_tun_open(int tun, int mode)
 120 {
 121         struct ifreq ifr;
 122         char name[100];
 123         int fd = -1, sock, flag;
 124         const char *tunbase = "tun";
 125
 126         if (mode == SSH_TUNMODE_ETHERNET) {
 127 #ifdef SSH_TUN_NO_L2
 128                 debug("%s: no layer 2 tunnelling support", __func__);
 129                 return (-1);
 130 #else
 131                 tunbase = "tap";
 132 #endif
 133         }
 134
 135         /* Open the tunnel device */
 136         if (tun <= SSH_TUNID_MAX) {
 137                 snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
 138                 fd = open(name, O_RDWR);
 139         } else if (tun == SSH_TUNID_ANY) {
 140                 for (tun = 100; tun >= 0; tun--) {
 141                         snprintf(name, sizeof(name), "/dev/%s%d",
 142                             tunbase, tun);
 143                         if ((fd = open(name, O_RDWR)) >= 0)
 144                                 break;
 145                 }
 146         } else {
 147                 debug("%s: invalid tunnel %u\n", __func__, tun);
 148                 return (-1);
 149         }
 150
 151         if (fd < 0) {
 152                 debug("%s: %s open failed: %s", __func__, name,
 153                     strerror(errno));
 154                 return (-1);
 155         }
 156
 157         /* Turn on tunnel headers */
 158         flag = 1;
 159 #if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
 160         if (mode != SSH_TUNMODE_ETHERNET &&
 161             ioctl(fd, TUNSIFHEAD, &flag) == -1) {
 162                 debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd,
 163                     strerror(errno));
 164                 close(fd);
 165         }
 166 #endif
 167
 168         debug("%s: %s mode %d fd %d", __func__, name, mode, fd);
 169
 170         /* Set the tunnel device operation mode */
 171         snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
 172         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
 173                 goto failed;
 174
 175         if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
 176                 goto failed;
 177         if ((ifr.ifr_flags & IFF_UP) == 0) {
 178                 ifr.ifr_flags |= IFF_UP;
 179                 if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
 180                         goto failed;
 181         }
 182
 183         close(sock);
 184         return (fd);
 185
 186  failed:
 187         if (fd >= 0)
 188                 close(fd);
 189         if (sock >= 0)
 190                 close(sock);
 191         debug("%s: failed to set %s mode %d: %s", __func__, name,
 192             mode, strerror(errno));
 193         return (-1);
 194 }
 195 #endif /* SSH_TUN_FREEBSD */
 196
 197 /*
 198  * System-specific channel filters
 199  */
 200
 201 #if defined(SSH_TUN_FILTER)
 202 #define OPENBSD_AF_INET         2
 203 #define OPENBSD_AF_INET6        24
 204
 205 int
 206 sys_tun_infilter(struct Channel *c, char *buf, int len)
 207 {
 208 #if defined(SSH_TUN_PREPEND_AF)
 209         char rbuf[CHAN_RBUF];
 210         struct ip *iph;
 211 #endif
 212         u_int32_t *af;
 213         char *ptr = buf;
 214         int r;
 215
 216 #if defined(SSH_TUN_PREPEND_AF)
 217         if (len <= 0 || len > (int)(sizeof(rbuf) - sizeof(*af)))
 218                 return (-1);
 219         ptr = (char *)&rbuf[0];
 220         bcopy(buf, ptr + sizeof(u_int32_t), len);
 221         len += sizeof(u_int32_t);
 222         af = (u_int32_t *)ptr;
 223
 224         iph = (struct ip *)(ptr + sizeof(u_int32_t));
 225         switch (iph->ip_v) {
 226         case 6:
 227                 *af = AF_INET6;
 228                 break;
 229         case 4:
 230         default:
 231                 *af = AF_INET;
 232                 break;
 233         }
 234 #endif
 235
 236 #if defined(SSH_TUN_COMPAT_AF)
 237         if (len < (int)sizeof(u_int32_t))
 238                 return (-1);
 239
 240         af = (u_int32_t *)ptr;
 241         if (*af == htonl(AF_INET6))
 242                 *af = htonl(OPENBSD_AF_INET6);
 243         else
 244                 *af = htonl(OPENBSD_AF_INET);
 245 #endif
 246
 247         if ((r = sshbuf_put_string(&c->input, ptr, len)) != 0)
 248                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 249         return (0);
 250 }
 251
 252 u_char *
 253 sys_tun_outfilter(struct Channel *c, u_char **data, u_int *dlen)
 254 {
 255         u_char *buf;
 256         u_int32_t *af;
 257         int r;
 258         size_t xxx_dlen;
 259
 260         /* XXX new API is incompatible with this signature. */
 261         if ((r = sshbuf_get_string(&c->output, data, &xxx_dlen)) != 0)
 262                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 263         if (dlen != NULL)
 264                 *dlen = xxx_dlen;
 265         if (*dlen < sizeof(*af))
 266                 return (NULL);
 267         buf = *data;
 268
 269 #if defined(SSH_TUN_PREPEND_AF)
 270         *dlen -= sizeof(u_int32_t);
 271         buf = *data + sizeof(u_int32_t);
 272 #elif defined(SSH_TUN_COMPAT_AF)
 273         af = ntohl(*(u_int32_t *)buf);
 274         if (*af == OPENBSD_AF_INET6)
 275                 *af = htonl(AF_INET6);
 276         else
 277                 *af = htonl(AF_INET);
 278 #endif
 279
 280         return (buf);
 281 }
 282 #endif /* SSH_TUN_FILTER */