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/*
* Copyright (c) 2005 Reyk Floeter <reyk@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include "openbsd-compat/sys-queue.h"
#include "log.h"
#include "misc.h"
#include "sshbuf.h"
#include "channels.h"
#include "ssherr.h"
/*
* This is the portable version of the SSH tunnel forwarding, it
* uses some preprocessor definitions for various platform-specific
* settings.
*
* SSH_TUN_LINUX Use the (newer) Linux tun/tap device
* SSH_TUN_FREEBSD Use the FreeBSD tun/tap device
* SSH_TUN_COMPAT_AF Translate the OpenBSD address family
* SSH_TUN_PREPEND_AF Prepend/remove the address family
*/
/*
* System-specific tunnel open function
*/
#if defined(SSH_TUN_LINUX)
#include <linux/if.h>
#include <linux/if_tun.h>
int
sys_tun_open(int tun, int mode, char **ifname)
{
struct ifreq ifr;
int fd = -1;
const char *name = NULL;
if (ifname != NULL)
*ifname = NULL;
if ((fd = open("/dev/net/tun", O_RDWR)) == -1) {
debug("%s: failed to open tunnel control interface: %s",
__func__, strerror(errno));
return (-1);
}
bzero(&ifr, sizeof(ifr));
if (mode == SSH_TUNMODE_ETHERNET) {
ifr.ifr_flags = IFF_TAP;
name = "tap%d";
} else {
ifr.ifr_flags = IFF_TUN;
name = "tun%d";
}
ifr.ifr_flags |= IFF_NO_PI;
if (tun != SSH_TUNID_ANY) {
if (tun > SSH_TUNID_MAX) {
debug("%s: invalid tunnel id %x: %s", __func__,
tun, strerror(errno));
goto failed;
}
snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun);
}
if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
debug("%s: failed to configure tunnel (mode %d): %s", __func__,
mode, strerror(errno));
goto failed;
}
if (tun == SSH_TUNID_ANY)
debug("%s: tunnel mode %d fd %d", __func__, mode, fd);
else
debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);
if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)))
goto failed;
return (fd);
failed:
close(fd);
return (-1);
}
#endif /* SSH_TUN_LINUX */
#ifdef SSH_TUN_FREEBSD
#include <sys/socket.h>
#include <net/if.h>
#ifdef HAVE_NET_IF_TUN_H
#include <net/if_tun.h>
#endif
int
sys_tun_open(int tun, int mode, char **ifname)
{
struct ifreq ifr;
char name[100];
int fd = -1, sock, flag;
const char *tunbase = "tun";
if (ifname != NULL)
*ifname = NULL;
if (mode == SSH_TUNMODE_ETHERNET) {
#ifdef SSH_TUN_NO_L2
debug("%s: no layer 2 tunnelling support", __func__);
return (-1);
#else
tunbase = "tap";
#endif
}
/* Open the tunnel device */
if (tun <= SSH_TUNID_MAX) {
snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
fd = open(name, O_RDWR);
} else if (tun == SSH_TUNID_ANY) {
for (tun = 100; tun >= 0; tun--) {
snprintf(name, sizeof(name), "/dev/%s%d",
tunbase, tun);
if ((fd = open(name, O_RDWR)) >= 0)
break;
}
} else {
debug("%s: invalid tunnel %u\n", __func__, tun);
return (-1);
}
if (fd < 0) {
debug("%s: %s open failed: %s", __func__, name,
strerror(errno));
return (-1);
}
/* Turn on tunnel headers */
flag = 1;
#if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
if (mode != SSH_TUNMODE_ETHERNET &&
ioctl(fd, TUNSIFHEAD, &flag) == -1) {
debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd,
strerror(errno));
close(fd);
}
#endif
debug("%s: %s mode %d fd %d", __func__, name, mode, fd);
/* Set the tunnel device operation mode */
snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
goto failed;
if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
goto failed;
if ((ifr.ifr_flags & IFF_UP) == 0) {
ifr.ifr_flags |= IFF_UP;
if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
goto failed;
}
if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)))
goto failed;
close(sock);
return (fd);
failed:
if (fd >= 0)
close(fd);
if (sock >= 0)
close(sock);
debug("%s: failed to set %s mode %d: %s", __func__, name,
mode, strerror(errno));
return (-1);
}
#endif /* SSH_TUN_FREEBSD */
/*
* System-specific channel filters
*/
#if defined(SSH_TUN_FILTER)
/*
* The tunnel forwarding protocol prepends the address family of forwarded
* IP packets using OpenBSD's numbers.
*/
#define OPENBSD_AF_INET 2
#define OPENBSD_AF_INET6 24
int
sys_tun_infilter(struct ssh *ssh, struct Channel *c, char *buf, int _len)
{
int r;
size_t len;
char *ptr = buf;
#if defined(SSH_TUN_PREPEND_AF)
char rbuf[CHAN_RBUF];
struct ip iph;
#endif
#if defined(SSH_TUN_PREPEND_AF) || defined(SSH_TUN_COMPAT_AF)
u_int32_t af;
#endif
/* XXX update channel input filter API to use unsigned length */
if (_len < 0)
return -1;
len = _len;
#if defined(SSH_TUN_PREPEND_AF)
if (len <= sizeof(iph) || len > sizeof(rbuf) - 4)
return -1;
/* Determine address family from packet IP header. */
memcpy(&iph, buf, sizeof(iph));
af = iph.ip_v == 6 ? OPENBSD_AF_INET6 : OPENBSD_AF_INET;
/* Prepend address family to packet using OpenBSD constants */
memcpy(rbuf + 4, buf, len);
len += 4;
POKE_U32(rbuf, af);
ptr = rbuf;
#elif defined(SSH_TUN_COMPAT_AF)
/* Convert existing address family header to OpenBSD value */
if (len <= 4)
return -1;
af = PEEK_U32(buf);
/* Put it back */
POKE_U32(buf, af == AF_INET6 ? OPENBSD_AF_INET6 : OPENBSD_AF_INET);
#endif
if ((r = sshbuf_put_string(c->input, ptr, len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
return (0);
}
u_char *
sys_tun_outfilter(struct ssh *ssh, struct Channel *c,
u_char **data, size_t *dlen)
{
u_char *buf;
u_int32_t af;
int r;
/* XXX new API is incompatible with this signature. */
if ((r = sshbuf_get_string(c->output, data, dlen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (*dlen < sizeof(af))
return (NULL);
buf = *data;
#if defined(SSH_TUN_PREPEND_AF)
/* skip address family */
*dlen -= sizeof(af);
buf = *data + sizeof(af);
#elif defined(SSH_TUN_COMPAT_AF)
/* translate address family */
af = (PEEK_U32(buf) == OPENBSD_AF_INET6) ? AF_INET6 : AF_INET;
POKE_U32(buf, af);
#endif
return (buf);
}
#endif /* SSH_TUN_FILTER */
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