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
57 int
sys_tun_open(int tun,int mode)58 sys_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
117 int
sys_tun_open(int tun,int mode)118 sys_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
204 int
sys_tun_infilter(struct Channel * c,char * buf,int len)205 sys_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
249 u_char *
sys_tun_outfilter(struct Channel * c,u_char ** data,u_int * dlen)250 sys_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