1 /*
2 * Dropbear SSH
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * Copyright (c) 2004 by Mihnea Stoenescu
6 * All rights reserved.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24 * SOFTWARE. */
25
26 #include "includes.h"
27 #include "ssh.h"
28 #include "tcpfwd.h"
29 #include "dbutil.h"
30 #include "session.h"
31 #include "buffer.h"
32 #include "packet.h"
33 #include "listener.h"
34 #include "runopts.h"
35
36 #ifdef ENABLE_SVR_REMOTETCPFWD
37
38 static void send_msg_request_success();
39 static void send_msg_request_failure();
40 static int svr_cancelremotetcp();
41 static int svr_remotetcpreq();
42 static int newtcpdirect(struct Channel * channel);
43
44
45 const struct ChanType svr_chan_tcpdirect = {
46 1, /* sepfds */
47 "direct-tcpip",
48 newtcpdirect, /* init */
49 NULL, /* checkclose */
50 NULL, /* reqhandler */
51 NULL /* closehandler */
52 };
53
54 static const struct ChanType svr_chan_tcpremote = {
55 1, /* sepfds */
56 "forwarded-tcpip",
57 NULL,
58 NULL,
59 NULL,
60 NULL
61 };
62
63 /* At the moment this is completely used for tcp code (with the name reflecting
64 * that). If new request types are added, this should be replaced with code
65 * similar to the request-switching in chansession.c */
recv_msg_global_request_remotetcp()66 void recv_msg_global_request_remotetcp() {
67
68 unsigned char* reqname = NULL;
69 unsigned int namelen;
70 unsigned int wantreply = 0;
71 int ret = DROPBEAR_FAILURE;
72
73 TRACE(("enter recv_msg_global_request_remotetcp"))
74
75 if (svr_opts.noremotetcp) {
76 TRACE(("leave recv_msg_global_request_remotetcp: remote tcp forwarding disabled"))
77 goto out;
78 }
79
80 reqname = buf_getstring(ses.payload, &namelen);
81 wantreply = buf_getbool(ses.payload);
82
83 if (namelen > MAX_NAME_LEN) {
84 TRACE(("name len is wrong: %d", namelen))
85 goto out;
86 }
87
88 if (strcmp("tcpip-forward", reqname) == 0) {
89 ret = svr_remotetcpreq();
90 } else if (strcmp("cancel-tcpip-forward", reqname) == 0) {
91 ret = svr_cancelremotetcp();
92 } else {
93 TRACE(("reqname isn't tcpip-forward: '%s'", reqname))
94 }
95
96 out:
97 if (wantreply) {
98 if (ret == DROPBEAR_SUCCESS) {
99 send_msg_request_success();
100 } else {
101 send_msg_request_failure();
102 }
103 }
104
105 m_free(reqname);
106
107 TRACE(("leave recv_msg_global_request"))
108 }
109
110
send_msg_request_success()111 static void send_msg_request_success() {
112
113 CHECKCLEARTOWRITE();
114 buf_putbyte(ses.writepayload, SSH_MSG_REQUEST_SUCCESS);
115 encrypt_packet();
116
117 }
118
send_msg_request_failure()119 static void send_msg_request_failure() {
120
121 CHECKCLEARTOWRITE();
122 buf_putbyte(ses.writepayload, SSH_MSG_REQUEST_FAILURE);
123 encrypt_packet();
124
125 }
126
matchtcp(void * typedata1,void * typedata2)127 static int matchtcp(void* typedata1, void* typedata2) {
128
129 const struct TCPListener *info1 = (struct TCPListener*)typedata1;
130 const struct TCPListener *info2 = (struct TCPListener*)typedata2;
131
132 return (info1->listenport == info2->listenport)
133 && (info1->chantype == info2->chantype)
134 && (strcmp(info1->listenaddr, info2->listenaddr) == 0);
135 }
136
svr_cancelremotetcp()137 static int svr_cancelremotetcp() {
138
139 int ret = DROPBEAR_FAILURE;
140 unsigned char * bindaddr = NULL;
141 unsigned int addrlen;
142 unsigned int port;
143 struct Listener * listener = NULL;
144 struct TCPListener tcpinfo;
145
146 TRACE(("enter cancelremotetcp"))
147
148 bindaddr = buf_getstring(ses.payload, &addrlen);
149 if (addrlen > MAX_IP_LEN) {
150 TRACE(("addr len too long: %d", addrlen))
151 goto out;
152 }
153
154 port = buf_getint(ses.payload);
155
156 tcpinfo.sendaddr = NULL;
157 tcpinfo.sendport = 0;
158 tcpinfo.listenaddr = bindaddr;
159 tcpinfo.listenport = port;
160 listener = get_listener(CHANNEL_ID_TCPFORWARDED, &tcpinfo, matchtcp);
161 if (listener) {
162 remove_listener( listener );
163 ret = DROPBEAR_SUCCESS;
164 }
165
166 out:
167 m_free(bindaddr);
168 TRACE(("leave cancelremotetcp"))
169 return ret;
170 }
171
svr_remotetcpreq()172 static int svr_remotetcpreq() {
173
174 int ret = DROPBEAR_FAILURE;
175 unsigned char * bindaddr = NULL;
176 unsigned int addrlen;
177 struct TCPListener *tcpinfo = NULL;
178 unsigned int port;
179
180 TRACE(("enter remotetcpreq"))
181
182 bindaddr = buf_getstring(ses.payload, &addrlen);
183 if (addrlen > MAX_IP_LEN) {
184 TRACE(("addr len too long: %d", addrlen))
185 goto out;
186 }
187
188 port = buf_getint(ses.payload);
189
190 if (port == 0) {
191 dropbear_log(LOG_INFO, "Server chosen tcpfwd ports are unsupported");
192 goto out;
193 }
194
195 if (port < 1 || port > 65535) {
196 TRACE(("invalid port: %d", port))
197 goto out;
198 }
199
200 if (!ses.allowprivport && port < IPPORT_RESERVED) {
201 TRACE(("can't assign port < 1024 for non-root"))
202 goto out;
203 }
204
205 tcpinfo = (struct TCPListener*)m_malloc(sizeof(struct TCPListener));
206 tcpinfo->sendaddr = NULL;
207 tcpinfo->sendport = 0;
208 tcpinfo->listenaddr = bindaddr;
209 tcpinfo->listenport = port;
210 tcpinfo->chantype = &svr_chan_tcpremote;
211 tcpinfo->tcp_type = forwarded;
212
213 ret = listen_tcpfwd(tcpinfo);
214
215 out:
216 if (ret == DROPBEAR_FAILURE) {
217 /* we only free it if a listener wasn't created, since the listener
218 * has to remember it if it's to be cancelled */
219 m_free(bindaddr);
220 m_free(tcpinfo);
221 }
222 TRACE(("leave remotetcpreq"))
223 return ret;
224 }
225
226 /* Called upon creating a new direct tcp channel (ie we connect out to an
227 * address */
newtcpdirect(struct Channel * channel)228 static int newtcpdirect(struct Channel * channel) {
229
230 unsigned char* desthost = NULL;
231 unsigned int destport;
232 unsigned char* orighost = NULL;
233 unsigned int origport;
234 char portstring[NI_MAXSERV];
235 int sock;
236 int len;
237 int err = SSH_OPEN_ADMINISTRATIVELY_PROHIBITED;
238
239 if (svr_opts.nolocaltcp) {
240 TRACE(("leave newtcpdirect: local tcp forwarding disabled"))
241 goto out;
242 }
243
244 desthost = buf_getstring(ses.payload, &len);
245 if (len > MAX_HOST_LEN) {
246 TRACE(("leave newtcpdirect: desthost too long"))
247 goto out;
248 }
249
250 destport = buf_getint(ses.payload);
251
252 orighost = buf_getstring(ses.payload, &len);
253 if (len > MAX_HOST_LEN) {
254 TRACE(("leave newtcpdirect: orighost too long"))
255 goto out;
256 }
257
258 origport = buf_getint(ses.payload);
259
260 /* best be sure */
261 if (origport > 65535 || destport > 65535) {
262 TRACE(("leave newtcpdirect: port > 65535"))
263 goto out;
264 }
265
266 snprintf(portstring, sizeof(portstring), "%d", destport);
267 sock = connect_remote(desthost, portstring, 1, NULL);
268 if (sock < 0) {
269 err = SSH_OPEN_CONNECT_FAILED;
270 TRACE(("leave newtcpdirect: sock failed"))
271 goto out;
272 }
273
274 ses.maxfd = MAX(ses.maxfd, sock);
275
276 /* We don't set readfd, that will get set after the connection's
277 * progress succeeds */
278 channel->writefd = sock;
279 channel->initconn = 1;
280
281 err = SSH_OPEN_IN_PROGRESS;
282
283 out:
284 m_free(desthost);
285 m_free(orighost);
286 TRACE(("leave newtcpdirect: err %d", err))
287 return err;
288 }
289
290 #endif
291