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 file contains various portability code for network support,
41 * including tun/tap forwarding and routing domains.
42 */
43
44#if defined(SYS_RDOMAIN_LINUX) || defined(SSH_TUN_LINUX)
45#include <linux/if.h>
46#endif
47
48#if defined(SYS_RDOMAIN_LINUX)
49char *
50sys_get_rdomain(int fd)
51{
52	char dev[IFNAMSIZ + 1];
53	socklen_t len = sizeof(dev) - 1;
54
55	if (getsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, dev, &len) == -1) {
56		error("%s: cannot determine VRF for fd=%d : %s",
57		    __func__, fd, strerror(errno));
58		return NULL;
59	}
60	dev[len] = '\0';
61	return strdup(dev);
62}
63
64int
65sys_set_rdomain(int fd, const char *name)
66{
67	if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE,
68	    name, strlen(name)) == -1) {
69		error("%s: setsockopt(%d, SO_BINDTODEVICE, %s): %s",
70		      __func__, fd, name, strerror(errno));
71		return -1;
72	}
73	return 0;
74}
75
76int
77sys_valid_rdomain(const char *name)
78{
79	int fd;
80
81	/*
82	 * This is a pretty crappy way to test. It would be better to
83	 * check whether "name" represents a VRF device, but apparently
84	 * that requires an rtnetlink transaction.
85	 */
86	if ((fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
87		return 0;
88	if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE,
89	    name, strlen(name)) == -1) {
90		close(fd);
91		return 0;
92	}
93	close(fd);
94	return 1;
95}
96#elif defined(SYS_RDOMAIN_XXX)
97/* XXX examples */
98char *
99sys_get_rdomain(int fd)
100{
101	return NULL;
102}
103
104int
105sys_set_rdomain(int fd, const char *name)
106{
107	return -1;
108}
109
110int
111valid_rdomain(const char *name)
112{
113	return 0;
114}
115
116void
117sys_set_process_rdomain(const char *name)
118{
119	fatal("%s: not supported", __func__);
120}
121#endif /* defined(SYS_RDOMAIN_XXX) */
122
123/*
124 * This is the portable version of the SSH tunnel forwarding, it
125 * uses some preprocessor definitions for various platform-specific
126 * settings.
127 *
128 * SSH_TUN_LINUX	Use the (newer) Linux tun/tap device
129 * SSH_TUN_FREEBSD	Use the FreeBSD tun/tap device
130 * SSH_TUN_COMPAT_AF	Translate the OpenBSD address family
131 * SSH_TUN_PREPEND_AF	Prepend/remove the address family
132 */
133
134/*
135 * System-specific tunnel open function
136 */
137
138#if defined(SSH_TUN_LINUX)
139#include <linux/if_tun.h>
140
141int
142sys_tun_open(int tun, int mode, char **ifname)
143{
144	struct ifreq ifr;
145	int fd = -1;
146	const char *name = NULL;
147
148	if (ifname != NULL)
149		*ifname = NULL;
150
151	if ((fd = open("/dev/net/tun", O_RDWR)) == -1) {
152		debug("%s: failed to open tunnel control interface: %s",
153		    __func__, strerror(errno));
154		return (-1);
155	}
156
157	bzero(&ifr, sizeof(ifr));
158
159	if (mode == SSH_TUNMODE_ETHERNET) {
160		ifr.ifr_flags = IFF_TAP;
161		name = "tap%d";
162	} else {
163		ifr.ifr_flags = IFF_TUN;
164		name = "tun%d";
165	}
166	ifr.ifr_flags |= IFF_NO_PI;
167
168	if (tun != SSH_TUNID_ANY) {
169		if (tun > SSH_TUNID_MAX) {
170			debug("%s: invalid tunnel id %x: %s", __func__,
171			    tun, strerror(errno));
172			goto failed;
173		}
174		snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun);
175	}
176
177	if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
178		debug("%s: failed to configure tunnel (mode %d): %s", __func__,
179		    mode, strerror(errno));
180		goto failed;
181	}
182
183	if (tun == SSH_TUNID_ANY)
184		debug("%s: tunnel mode %d fd %d", __func__, mode, fd);
185	else
186		debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);
187
188	if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)) == NULL)
189		goto failed;
190
191	return (fd);
192
193 failed:
194	close(fd);
195	return (-1);
196}
197#endif /* SSH_TUN_LINUX */
198
199#ifdef SSH_TUN_FREEBSD
200#include <sys/socket.h>
201#include <net/if.h>
202
203#ifdef HAVE_NET_IF_TUN_H
204#include <net/if_tun.h>
205#endif
206
207int
208sys_tun_open(int tun, int mode, char **ifname)
209{
210	struct ifreq ifr;
211	char name[100];
212	int fd = -1, sock, flag;
213	const char *tunbase = "tun";
214
215	if (ifname != NULL)
216		*ifname = NULL;
217
218	if (mode == SSH_TUNMODE_ETHERNET) {
219#ifdef SSH_TUN_NO_L2
220		debug("%s: no layer 2 tunnelling support", __func__);
221		return (-1);
222#else
223		tunbase = "tap";
224#endif
225	}
226
227	/* Open the tunnel device */
228	if (tun <= SSH_TUNID_MAX) {
229		snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
230		fd = open(name, O_RDWR);
231	} else if (tun == SSH_TUNID_ANY) {
232		for (tun = 100; tun >= 0; tun--) {
233			snprintf(name, sizeof(name), "/dev/%s%d",
234			    tunbase, tun);
235			if ((fd = open(name, O_RDWR)) >= 0)
236				break;
237		}
238	} else {
239		debug("%s: invalid tunnel %u\n", __func__, tun);
240		return (-1);
241	}
242
243	if (fd < 0) {
244		debug("%s: %s open failed: %s", __func__, name,
245		    strerror(errno));
246		return (-1);
247	}
248
249	/* Turn on tunnel headers */
250	flag = 1;
251#if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
252	if (mode != SSH_TUNMODE_ETHERNET &&
253	    ioctl(fd, TUNSIFHEAD, &flag) == -1) {
254		debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd,
255		    strerror(errno));
256		close(fd);
257	}
258#endif
259
260	debug("%s: %s mode %d fd %d", __func__, name, mode, fd);
261
262	/* Set the tunnel device operation mode */
263	snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
264	if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
265		goto failed;
266
267	if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
268		goto failed;
269	if ((ifr.ifr_flags & IFF_UP) == 0) {
270		ifr.ifr_flags |= IFF_UP;
271		if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
272			goto failed;
273	}
274
275	if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)) == NULL)
276		goto failed;
277
278	close(sock);
279	return (fd);
280
281 failed:
282	if (fd >= 0)
283		close(fd);
284	if (sock >= 0)
285		close(sock);
286	debug("%s: failed to set %s mode %d: %s", __func__, name,
287	    mode, strerror(errno));
288	return (-1);
289}
290#endif /* SSH_TUN_FREEBSD */
291
292/*
293 * System-specific channel filters
294 */
295
296#if defined(SSH_TUN_FILTER)
297/*
298 * The tunnel forwarding protocol prepends the address family of forwarded
299 * IP packets using OpenBSD's numbers.
300 */
301#define OPENBSD_AF_INET		2
302#define OPENBSD_AF_INET6	24
303
304int
305sys_tun_infilter(struct ssh *ssh, struct Channel *c, char *buf, int _len)
306{
307	int r;
308	size_t len;
309	char *ptr = buf;
310#if defined(SSH_TUN_PREPEND_AF)
311	char rbuf[CHAN_RBUF];
312	struct ip iph;
313#endif
314#if defined(SSH_TUN_PREPEND_AF) || defined(SSH_TUN_COMPAT_AF)
315	u_int32_t af;
316#endif
317
318	/* XXX update channel input filter API to use unsigned length */
319	if (_len < 0)
320		return -1;
321	len = _len;
322
323#if defined(SSH_TUN_PREPEND_AF)
324	if (len <= sizeof(iph) || len > sizeof(rbuf) - 4)
325		return -1;
326	/* Determine address family from packet IP header. */
327	memcpy(&iph, buf, sizeof(iph));
328	af = iph.ip_v == 6 ? OPENBSD_AF_INET6 : OPENBSD_AF_INET;
329	/* Prepend address family to packet using OpenBSD constants */
330	memcpy(rbuf + 4, buf, len);
331	len += 4;
332	POKE_U32(rbuf, af);
333	ptr = rbuf;
334#elif defined(SSH_TUN_COMPAT_AF)
335	/* Convert existing address family header to OpenBSD value */
336	if (len <= 4)
337		return -1;
338	af = PEEK_U32(buf);
339	/* Put it back */
340	POKE_U32(buf, af == AF_INET6 ? OPENBSD_AF_INET6 : OPENBSD_AF_INET);
341#endif
342
343	if ((r = sshbuf_put_string(c->input, ptr, len)) != 0)
344		fatal("%s: buffer error: %s", __func__, ssh_err(r));
345	return (0);
346}
347
348u_char *
349sys_tun_outfilter(struct ssh *ssh, struct Channel *c,
350    u_char **data, size_t *dlen)
351{
352	u_char *buf;
353	u_int32_t af;
354	int r;
355
356	/* XXX new API is incompatible with this signature. */
357	if ((r = sshbuf_get_string(c->output, data, dlen)) != 0)
358		fatal("%s: buffer error: %s", __func__, ssh_err(r));
359	if (*dlen < sizeof(af))
360		return (NULL);
361	buf = *data;
362
363#if defined(SSH_TUN_PREPEND_AF)
364	/* skip address family */
365	*dlen -= sizeof(af);
366	buf = *data + sizeof(af);
367#elif defined(SSH_TUN_COMPAT_AF)
368	/* translate address family */
369	af = (PEEK_U32(buf) == OPENBSD_AF_INET6) ? AF_INET6 : AF_INET;
370	POKE_U32(buf, af);
371#endif
372	return (buf);
373}
374#endif /* SSH_TUN_FILTER */
375