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)
49 char *
sys_get_rdomain(int fd)50 sys_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
64 int
sys_set_rdomain(int fd,const char * name)65 sys_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
76 int
sys_valid_rdomain(const char * name)77 sys_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 */
98 char *
sys_get_rdomain(int fd)99 sys_get_rdomain(int fd)
100 {
101 return NULL;
102 }
103
104 int
sys_set_rdomain(int fd,const char * name)105 sys_set_rdomain(int fd, const char *name)
106 {
107 return -1;
108 }
109
110 int
valid_rdomain(const char * name)111 valid_rdomain(const char *name)
112 {
113 return 0;
114 }
115
116 void
sys_set_process_rdomain(const char * name)117 sys_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 #define TUN_CTRL_DEV "/dev/net/tun"
141
142 int
sys_tun_open(int tun,int mode,char ** ifname)143 sys_tun_open(int tun, int mode, char **ifname)
144 {
145 struct ifreq ifr;
146 int fd = -1;
147 const char *name = NULL;
148
149 if (ifname != NULL)
150 *ifname = NULL;
151 if ((fd = open(TUN_CTRL_DEV, O_RDWR)) == -1) {
152 debug("%s: failed to open tunnel control device \"%s\": %s",
153 __func__, TUN_CTRL_DEV, 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
207 int
sys_tun_open(int tun,int mode,char ** ifname)208 sys_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
304 int
sys_tun_infilter(struct ssh * ssh,struct Channel * c,char * buf,int _len)305 sys_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
348 u_char *
sys_tun_outfilter(struct ssh * ssh,struct Channel * c,u_char ** data,size_t * dlen)349 sys_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