xref: /freebsd/crypto/openssh/auth-options.c (revision 271c3a9060f2ee55607ebe146523f888e1db2654)
1 /* $OpenBSD: auth-options.c,v 1.43 2008/06/10 23:06:19 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
6  * As far as I am concerned, the code I have written for this software
7  * can be used freely for any purpose.  Any derived versions of this
8  * software must be clearly marked as such, and if the derived work is
9  * incompatible with the protocol description in the RFC file, it must be
10  * called by a name other than "ssh" or "Secure Shell".
11  */
12 
13 #include "includes.h"
14 
15 #include <sys/types.h>
16 
17 #include <netdb.h>
18 #include <pwd.h>
19 #include <string.h>
20 #include <stdio.h>
21 #include <stdarg.h>
22 
23 #include "openbsd-compat/sys-queue.h"
24 #include "xmalloc.h"
25 #include "match.h"
26 #include "log.h"
27 #include "canohost.h"
28 #include "buffer.h"
29 #include "channels.h"
30 #include "auth-options.h"
31 #include "servconf.h"
32 #include "misc.h"
33 #include "key.h"
34 #include "hostfile.h"
35 #include "auth.h"
36 #ifdef GSSAPI
37 #include "ssh-gss.h"
38 #endif
39 #include "monitor_wrap.h"
40 
41 /* Flags set authorized_keys flags */
42 int no_port_forwarding_flag = 0;
43 int no_agent_forwarding_flag = 0;
44 int no_x11_forwarding_flag = 0;
45 int no_pty_flag = 0;
46 int no_user_rc = 0;
47 
48 /* "command=" option. */
49 char *forced_command = NULL;
50 
51 /* "environment=" options. */
52 struct envstring *custom_environment = NULL;
53 
54 /* "tunnel=" option. */
55 int forced_tun_device = -1;
56 
57 extern ServerOptions options;
58 
59 void
60 auth_clear_options(void)
61 {
62 	no_agent_forwarding_flag = 0;
63 	no_port_forwarding_flag = 0;
64 	no_pty_flag = 0;
65 	no_x11_forwarding_flag = 0;
66 	no_user_rc = 0;
67 	while (custom_environment) {
68 		struct envstring *ce = custom_environment;
69 		custom_environment = ce->next;
70 		xfree(ce->s);
71 		xfree(ce);
72 	}
73 	if (forced_command) {
74 		xfree(forced_command);
75 		forced_command = NULL;
76 	}
77 	forced_tun_device = -1;
78 	channel_clear_permitted_opens();
79 	auth_debug_reset();
80 }
81 
82 /*
83  * return 1 if access is granted, 0 if not.
84  * side effect: sets key option flags
85  */
86 int
87 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
88 {
89 	const char *cp;
90 	int i;
91 
92 	/* reset options */
93 	auth_clear_options();
94 
95 	if (!opts)
96 		return 1;
97 
98 	while (*opts && *opts != ' ' && *opts != '\t') {
99 		cp = "no-port-forwarding";
100 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
101 			auth_debug_add("Port forwarding disabled.");
102 			no_port_forwarding_flag = 1;
103 			opts += strlen(cp);
104 			goto next_option;
105 		}
106 		cp = "no-agent-forwarding";
107 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
108 			auth_debug_add("Agent forwarding disabled.");
109 			no_agent_forwarding_flag = 1;
110 			opts += strlen(cp);
111 			goto next_option;
112 		}
113 		cp = "no-X11-forwarding";
114 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
115 			auth_debug_add("X11 forwarding disabled.");
116 			no_x11_forwarding_flag = 1;
117 			opts += strlen(cp);
118 			goto next_option;
119 		}
120 		cp = "no-pty";
121 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
122 			auth_debug_add("Pty allocation disabled.");
123 			no_pty_flag = 1;
124 			opts += strlen(cp);
125 			goto next_option;
126 		}
127 		cp = "no-user-rc";
128 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
129 			auth_debug_add("User rc file execution disabled.");
130 			no_user_rc = 1;
131 			opts += strlen(cp);
132 			goto next_option;
133 		}
134 		cp = "command=\"";
135 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
136 			opts += strlen(cp);
137 			forced_command = xmalloc(strlen(opts) + 1);
138 			i = 0;
139 			while (*opts) {
140 				if (*opts == '"')
141 					break;
142 				if (*opts == '\\' && opts[1] == '"') {
143 					opts += 2;
144 					forced_command[i++] = '"';
145 					continue;
146 				}
147 				forced_command[i++] = *opts++;
148 			}
149 			if (!*opts) {
150 				debug("%.100s, line %lu: missing end quote",
151 				    file, linenum);
152 				auth_debug_add("%.100s, line %lu: missing end quote",
153 				    file, linenum);
154 				xfree(forced_command);
155 				forced_command = NULL;
156 				goto bad_option;
157 			}
158 			forced_command[i] = '\0';
159 			auth_debug_add("Forced command: %.900s", forced_command);
160 			opts++;
161 			goto next_option;
162 		}
163 		cp = "environment=\"";
164 		if (options.permit_user_env &&
165 		    strncasecmp(opts, cp, strlen(cp)) == 0) {
166 			char *s;
167 			struct envstring *new_envstring;
168 
169 			opts += strlen(cp);
170 			s = xmalloc(strlen(opts) + 1);
171 			i = 0;
172 			while (*opts) {
173 				if (*opts == '"')
174 					break;
175 				if (*opts == '\\' && opts[1] == '"') {
176 					opts += 2;
177 					s[i++] = '"';
178 					continue;
179 				}
180 				s[i++] = *opts++;
181 			}
182 			if (!*opts) {
183 				debug("%.100s, line %lu: missing end quote",
184 				    file, linenum);
185 				auth_debug_add("%.100s, line %lu: missing end quote",
186 				    file, linenum);
187 				xfree(s);
188 				goto bad_option;
189 			}
190 			s[i] = '\0';
191 			auth_debug_add("Adding to environment: %.900s", s);
192 			debug("Adding to environment: %.900s", s);
193 			opts++;
194 			new_envstring = xmalloc(sizeof(struct envstring));
195 			new_envstring->s = s;
196 			new_envstring->next = custom_environment;
197 			custom_environment = new_envstring;
198 			goto next_option;
199 		}
200 		cp = "from=\"";
201 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
202 			const char *remote_ip = get_remote_ipaddr();
203 			const char *remote_host = get_canonical_hostname(
204 			    options.use_dns);
205 			char *patterns = xmalloc(strlen(opts) + 1);
206 
207 			opts += strlen(cp);
208 			i = 0;
209 			while (*opts) {
210 				if (*opts == '"')
211 					break;
212 				if (*opts == '\\' && opts[1] == '"') {
213 					opts += 2;
214 					patterns[i++] = '"';
215 					continue;
216 				}
217 				patterns[i++] = *opts++;
218 			}
219 			if (!*opts) {
220 				debug("%.100s, line %lu: missing end quote",
221 				    file, linenum);
222 				auth_debug_add("%.100s, line %lu: missing end quote",
223 				    file, linenum);
224 				xfree(patterns);
225 				goto bad_option;
226 			}
227 			patterns[i] = '\0';
228 			opts++;
229 			switch (match_host_and_ip(remote_host, remote_ip,
230 			    patterns)) {
231 			case 1:
232 				xfree(patterns);
233 				/* Host name matches. */
234 				goto next_option;
235 			case -1:
236 				debug("%.100s, line %lu: invalid criteria",
237 				    file, linenum);
238 				auth_debug_add("%.100s, line %lu: "
239 				    "invalid criteria", file, linenum);
240 				/* FALLTHROUGH */
241 			case 0:
242 				xfree(patterns);
243 				logit("Authentication tried for %.100s with "
244 				    "correct key but not from a permitted "
245 				    "host (host=%.200s, ip=%.200s).",
246 				    pw->pw_name, remote_host, remote_ip);
247 				auth_debug_add("Your host '%.200s' is not "
248 				    "permitted to use this key for login.",
249 				    remote_host);
250 				break;
251 			}
252 			/* deny access */
253 			return 0;
254 		}
255 		cp = "permitopen=\"";
256 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
257 			char *host, *p;
258 			u_short port;
259 			char *patterns = xmalloc(strlen(opts) + 1);
260 
261 			opts += strlen(cp);
262 			i = 0;
263 			while (*opts) {
264 				if (*opts == '"')
265 					break;
266 				if (*opts == '\\' && opts[1] == '"') {
267 					opts += 2;
268 					patterns[i++] = '"';
269 					continue;
270 				}
271 				patterns[i++] = *opts++;
272 			}
273 			if (!*opts) {
274 				debug("%.100s, line %lu: missing end quote",
275 				    file, linenum);
276 				auth_debug_add("%.100s, line %lu: missing "
277 				    "end quote", file, linenum);
278 				xfree(patterns);
279 				goto bad_option;
280 			}
281 			patterns[i] = '\0';
282 			opts++;
283 			p = patterns;
284 			host = hpdelim(&p);
285 			if (host == NULL || strlen(host) >= NI_MAXHOST) {
286 				debug("%.100s, line %lu: Bad permitopen "
287 				    "specification <%.100s>", file, linenum,
288 				    patterns);
289 				auth_debug_add("%.100s, line %lu: "
290 				    "Bad permitopen specification", file,
291 				    linenum);
292 				xfree(patterns);
293 				goto bad_option;
294 			}
295 			host = cleanhostname(host);
296 			if (p == NULL || (port = a2port(p)) == 0) {
297 				debug("%.100s, line %lu: Bad permitopen port "
298 				    "<%.100s>", file, linenum, p ? p : "");
299 				auth_debug_add("%.100s, line %lu: "
300 				    "Bad permitopen port", file, linenum);
301 				xfree(patterns);
302 				goto bad_option;
303 			}
304 			if (options.allow_tcp_forwarding)
305 				channel_add_permitted_opens(host, port);
306 			xfree(patterns);
307 			goto next_option;
308 		}
309 		cp = "tunnel=\"";
310 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
311 			char *tun = NULL;
312 			opts += strlen(cp);
313 			tun = xmalloc(strlen(opts) + 1);
314 			i = 0;
315 			while (*opts) {
316 				if (*opts == '"')
317 					break;
318 				tun[i++] = *opts++;
319 			}
320 			if (!*opts) {
321 				debug("%.100s, line %lu: missing end quote",
322 				    file, linenum);
323 				auth_debug_add("%.100s, line %lu: missing end quote",
324 				    file, linenum);
325 				xfree(tun);
326 				forced_tun_device = -1;
327 				goto bad_option;
328 			}
329 			tun[i] = '\0';
330 			forced_tun_device = a2tun(tun, NULL);
331 			xfree(tun);
332 			if (forced_tun_device == SSH_TUNID_ERR) {
333 				debug("%.100s, line %lu: invalid tun device",
334 				    file, linenum);
335 				auth_debug_add("%.100s, line %lu: invalid tun device",
336 				    file, linenum);
337 				forced_tun_device = -1;
338 				goto bad_option;
339 			}
340 			auth_debug_add("Forced tun device: %d", forced_tun_device);
341 			opts++;
342 			goto next_option;
343 		}
344 next_option:
345 		/*
346 		 * Skip the comma, and move to the next option
347 		 * (or break out if there are no more).
348 		 */
349 		if (!*opts)
350 			fatal("Bugs in auth-options.c option processing.");
351 		if (*opts == ' ' || *opts == '\t')
352 			break;		/* End of options. */
353 		if (*opts != ',')
354 			goto bad_option;
355 		opts++;
356 		/* Process the next option. */
357 	}
358 
359 	if (!use_privsep)
360 		auth_debug_send();
361 
362 	/* grant access */
363 	return 1;
364 
365 bad_option:
366 	logit("Bad options in %.100s file, line %lu: %.50s",
367 	    file, linenum, opts);
368 	auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
369 	    file, linenum, opts);
370 
371 	if (!use_privsep)
372 		auth_debug_send();
373 
374 	/* deny access */
375 	return 0;
376 }
377