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 1.26 2002/07/30 17:03:55 markus Exp $");
14
15 #pragma ident "%Z%%M% %I% %E% SMI"
16
17 #include "xmalloc.h"
18 #include "match.h"
19 #include "log.h"
20 #include "canohost.h"
21 #include "channels.h"
22 #include "auth-options.h"
23 #include "servconf.h"
24 #include "misc.h"
25 #include "auth.h"
26
27 /* Flags set authorized_keys flags */
28 int no_port_forwarding_flag = 0;
29 int no_agent_forwarding_flag = 0;
30 int no_x11_forwarding_flag = 0;
31 int no_pty_flag = 0;
32
33 /* "command=" option. */
34 char *forced_command = NULL;
35
36 /* "environment=" options. */
37 struct envstring *custom_environment = NULL;
38
39 extern ServerOptions options;
40
41 void
42 auth_clear_options(void)
43 {
44 no_agent_forwarding_flag = 0;
45 no_port_forwarding_flag = 0;
46 no_pty_flag = 0;
47 no_x11_forwarding_flag = 0;
48 while (custom_environment) {
49 struct envstring *ce = custom_environment;
50 custom_environment = ce->next;
51 xfree(ce->s);
52 xfree(ce);
53 }
54 if (forced_command) {
55 xfree(forced_command);
56 forced_command = NULL;
57 }
58 channel_clear_permitted_opens();
59 auth_debug_reset();
60 }
61
62 /*
63 * return 1 if access is granted, 0 if not.
64 * side effect: sets key option flags
65 */
66 int
67 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
68 {
69 const char *cp;
70 int i;
71
72 /* reset options */
73 auth_clear_options();
74
75 if (!opts)
76 return 1;
77
78 while (*opts && *opts != ' ' && *opts != '\t') {
79 cp = "no-port-forwarding";
80 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
81 auth_debug_add("Port forwarding disabled.");
82 no_port_forwarding_flag = 1;
83 opts += strlen(cp);
84 goto next_option;
85 }
86 cp = "no-agent-forwarding";
87 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
88 auth_debug_add("Agent forwarding disabled.");
89 no_agent_forwarding_flag = 1;
90 opts += strlen(cp);
91 goto next_option;
92 }
93 cp = "no-X11-forwarding";
94 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
95 auth_debug_add("X11 forwarding disabled.");
96 no_x11_forwarding_flag = 1;
97 opts += strlen(cp);
98 goto next_option;
99 }
100 cp = "no-pty";
101 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
102 auth_debug_add("Pty allocation disabled.");
103 no_pty_flag = 1;
104 opts += strlen(cp);
105 goto next_option;
106 }
107 cp = "command=\"";
108 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
109 opts += strlen(cp);
110 forced_command = xmalloc(strlen(opts) + 1);
111 i = 0;
112 while (*opts) {
113 if (*opts == '"')
114 break;
115 if (*opts == '\\' && opts[1] == '"') {
116 opts += 2;
117 forced_command[i++] = '"';
118 continue;
119 }
120 forced_command[i++] = *opts++;
121 }
122 if (!*opts) {
123 debug("%.100s, line %lu: missing end quote",
124 file, linenum);
125 auth_debug_add("%.100s, line %lu: missing end quote",
126 file, linenum);
127 xfree(forced_command);
128 forced_command = NULL;
129 goto bad_option;
130 }
131 forced_command[i] = 0;
132 auth_debug_add("Forced command: %.900s", forced_command);
133 opts++;
134 goto next_option;
135 }
136 cp = "environment=\"";
137 if (options.permit_user_env &&
138 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 auth_debug_send();
285
286 /* grant access */
287 return 1;
288
289 bad_option:
290 log("Bad options in %.100s file, line %lu: %.50s",
291 file, linenum, opts);
292 auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
293 file, linenum, opts);
294
295 auth_debug_send();
296
297 /* deny access */
298 return 0;
299 }