xref: /freebsd/crypto/openssh/auth-options.c (revision ae83180158c4c937f170e31eff311b18c0286a93)
1 /*
2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4  *                    All rights reserved
5  * As far as I am concerned, the code I have written for this software
6  * can be used freely for any purpose.  Any derived versions of this
7  * software must be clearly marked as such, and if the derived work is
8  * incompatible with the protocol description in the RFC file, it must be
9  * called by a name other than "ssh" or "Secure Shell".
10  */
11 
12 #include "includes.h"
13 RCSID("$OpenBSD: auth-options.c,v 1.24 2002/05/13 20:44:58 markus Exp $");
14 
15 #include "packet.h"
16 #include "xmalloc.h"
17 #include "match.h"
18 #include "log.h"
19 #include "canohost.h"
20 #include "channels.h"
21 #include "auth-options.h"
22 #include "servconf.h"
23 #include "bufaux.h"
24 #include "misc.h"
25 #include "monitor_wrap.h"
26 #include "auth.h"
27 
28 /* Flags set authorized_keys flags */
29 int no_port_forwarding_flag = 0;
30 int no_agent_forwarding_flag = 0;
31 int no_x11_forwarding_flag = 0;
32 int no_pty_flag = 0;
33 
34 /* "command=" option. */
35 char *forced_command = NULL;
36 
37 /* "environment=" options. */
38 struct envstring *custom_environment = NULL;
39 
40 extern ServerOptions options;
41 
42 void
43 auth_clear_options(void)
44 {
45 	no_agent_forwarding_flag = 0;
46 	no_port_forwarding_flag = 0;
47 	no_pty_flag = 0;
48 	no_x11_forwarding_flag = 0;
49 	while (custom_environment) {
50 		struct envstring *ce = custom_environment;
51 		custom_environment = ce->next;
52 		xfree(ce->s);
53 		xfree(ce);
54 	}
55 	if (forced_command) {
56 		xfree(forced_command);
57 		forced_command = NULL;
58 	}
59 	channel_clear_permitted_opens();
60 	auth_debug_reset();
61 }
62 
63 /*
64  * return 1 if access is granted, 0 if not.
65  * side effect: sets key option flags
66  */
67 int
68 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
69 {
70 	const char *cp;
71 	int i;
72 
73 	/* reset options */
74 	auth_clear_options();
75 
76 	if (!opts)
77 		return 1;
78 
79 	while (*opts && *opts != ' ' && *opts != '\t') {
80 		cp = "no-port-forwarding";
81 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
82 			auth_debug_add("Port forwarding disabled.");
83 			no_port_forwarding_flag = 1;
84 			opts += strlen(cp);
85 			goto next_option;
86 		}
87 		cp = "no-agent-forwarding";
88 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
89 			auth_debug_add("Agent forwarding disabled.");
90 			no_agent_forwarding_flag = 1;
91 			opts += strlen(cp);
92 			goto next_option;
93 		}
94 		cp = "no-X11-forwarding";
95 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
96 			auth_debug_add("X11 forwarding disabled.");
97 			no_x11_forwarding_flag = 1;
98 			opts += strlen(cp);
99 			goto next_option;
100 		}
101 		cp = "no-pty";
102 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
103 			auth_debug_add("Pty allocation disabled.");
104 			no_pty_flag = 1;
105 			opts += strlen(cp);
106 			goto next_option;
107 		}
108 		cp = "command=\"";
109 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
110 			opts += strlen(cp);
111 			forced_command = xmalloc(strlen(opts) + 1);
112 			i = 0;
113 			while (*opts) {
114 				if (*opts == '"')
115 					break;
116 				if (*opts == '\\' && opts[1] == '"') {
117 					opts += 2;
118 					forced_command[i++] = '"';
119 					continue;
120 				}
121 				forced_command[i++] = *opts++;
122 			}
123 			if (!*opts) {
124 				debug("%.100s, line %lu: missing end quote",
125 				    file, linenum);
126 				auth_debug_add("%.100s, line %lu: missing end quote",
127 				    file, linenum);
128 				xfree(forced_command);
129 				forced_command = NULL;
130 				goto bad_option;
131 			}
132 			forced_command[i] = 0;
133 			auth_debug_add("Forced command: %.900s", forced_command);
134 			opts++;
135 			goto next_option;
136 		}
137 		cp = "environment=\"";
138 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
139 			char *s;
140 			struct envstring *new_envstring;
141 
142 			opts += strlen(cp);
143 			s = xmalloc(strlen(opts) + 1);
144 			i = 0;
145 			while (*opts) {
146 				if (*opts == '"')
147 					break;
148 				if (*opts == '\\' && opts[1] == '"') {
149 					opts += 2;
150 					s[i++] = '"';
151 					continue;
152 				}
153 				s[i++] = *opts++;
154 			}
155 			if (!*opts) {
156 				debug("%.100s, line %lu: missing end quote",
157 				    file, linenum);
158 				auth_debug_add("%.100s, line %lu: missing end quote",
159 				    file, linenum);
160 				xfree(s);
161 				goto bad_option;
162 			}
163 			s[i] = 0;
164 			auth_debug_add("Adding to environment: %.900s", s);
165 			debug("Adding to environment: %.900s", s);
166 			opts++;
167 			new_envstring = xmalloc(sizeof(struct envstring));
168 			new_envstring->s = s;
169 			new_envstring->next = custom_environment;
170 			custom_environment = new_envstring;
171 			goto next_option;
172 		}
173 		cp = "from=\"";
174 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
175 			const char *remote_ip = get_remote_ipaddr();
176 			const char *remote_host = get_canonical_hostname(
177 			    options.verify_reverse_mapping);
178 			char *patterns = xmalloc(strlen(opts) + 1);
179 
180 			opts += strlen(cp);
181 			i = 0;
182 			while (*opts) {
183 				if (*opts == '"')
184 					break;
185 				if (*opts == '\\' && opts[1] == '"') {
186 					opts += 2;
187 					patterns[i++] = '"';
188 					continue;
189 				}
190 				patterns[i++] = *opts++;
191 			}
192 			if (!*opts) {
193 				debug("%.100s, line %lu: missing end quote",
194 				    file, linenum);
195 				auth_debug_add("%.100s, line %lu: missing end quote",
196 				    file, linenum);
197 				xfree(patterns);
198 				goto bad_option;
199 			}
200 			patterns[i] = 0;
201 			opts++;
202 			if (match_host_and_ip(remote_host, remote_ip,
203 			    patterns) != 1) {
204 				xfree(patterns);
205 				log("Authentication tried for %.100s with "
206 				    "correct key but not from a permitted "
207 				    "host (host=%.200s, ip=%.200s).",
208 				    pw->pw_name, remote_host, remote_ip);
209 				auth_debug_add("Your host '%.200s' is not "
210 				    "permitted to use this key for login.",
211 				    remote_host);
212 				/* deny access */
213 				return 0;
214 			}
215 			xfree(patterns);
216 			/* Host name matches. */
217 			goto next_option;
218 		}
219 		cp = "permitopen=\"";
220 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
221 			char host[256], sport[6];
222 			u_short port;
223 			char *patterns = xmalloc(strlen(opts) + 1);
224 
225 			opts += strlen(cp);
226 			i = 0;
227 			while (*opts) {
228 				if (*opts == '"')
229 					break;
230 				if (*opts == '\\' && opts[1] == '"') {
231 					opts += 2;
232 					patterns[i++] = '"';
233 					continue;
234 				}
235 				patterns[i++] = *opts++;
236 			}
237 			if (!*opts) {
238 				debug("%.100s, line %lu: missing end quote",
239 				    file, linenum);
240 				auth_debug_add("%.100s, line %lu: missing end quote",
241 				    file, linenum);
242 				xfree(patterns);
243 				goto bad_option;
244 			}
245 			patterns[i] = 0;
246 			opts++;
247 			if (sscanf(patterns, "%255[^:]:%5[0-9]", host, sport) != 2 &&
248 			    sscanf(patterns, "%255[^/]/%5[0-9]", host, sport) != 2) {
249 				debug("%.100s, line %lu: Bad permitopen specification "
250 				    "<%.100s>", file, linenum, patterns);
251 				auth_debug_add("%.100s, line %lu: "
252 				    "Bad permitopen specification", file, linenum);
253 				xfree(patterns);
254 				goto bad_option;
255 			}
256 			if ((port = a2port(sport)) == 0) {
257 				debug("%.100s, line %lu: Bad permitopen port <%.100s>",
258 				    file, linenum, sport);
259 				auth_debug_add("%.100s, line %lu: "
260 				    "Bad permitopen port", file, linenum);
261 				xfree(patterns);
262 				goto bad_option;
263 			}
264 			if (options.allow_tcp_forwarding)
265 				channel_add_permitted_opens(host, port);
266 			xfree(patterns);
267 			goto next_option;
268 		}
269 next_option:
270 		/*
271 		 * Skip the comma, and move to the next option
272 		 * (or break out if there are no more).
273 		 */
274 		if (!*opts)
275 			fatal("Bugs in auth-options.c option processing.");
276 		if (*opts == ' ' || *opts == '\t')
277 			break;		/* End of options. */
278 		if (*opts != ',')
279 			goto bad_option;
280 		opts++;
281 		/* Process the next option. */
282 	}
283 
284 	if (!use_privsep)
285 		auth_debug_send();
286 
287 	/* grant access */
288 	return 1;
289 
290 bad_option:
291 	log("Bad options in %.100s file, line %lu: %.50s",
292 	    file, linenum, opts);
293 	auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
294 	    file, linenum, opts);
295 
296 	if (!use_privsep)
297 		auth_debug_send();
298 
299 	/* deny access */
300 	return 0;
301 }
302