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
57int
58sys_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
117int
118sys_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
204int
205sys_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
249u_char *
250sys_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 */
274