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30460aeb | 1 | /* $OpenBSD: auth2.c,v 1.113 2006/08/03 03:34:41 deraadt Exp $ */ |
3c0ef626 | 2 | /* |
3 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * | |
14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
24 | */ | |
25 | ||
26 | #include "includes.h" | |
3c0ef626 | 27 | |
30460aeb | 28 | #include <sys/types.h> |
29 | ||
30 | #include <pwd.h> | |
31 | #include <stdarg.h> | |
32 | #include <string.h> | |
33 | ||
3c0ef626 | 34 | #include "xmalloc.h" |
30460aeb | 35 | #include "ssh2.h" |
3c0ef626 | 36 | #include "packet.h" |
3c0ef626 | 37 | #include "log.h" |
30460aeb | 38 | #include "buffer.h" |
3c0ef626 | 39 | #include "servconf.h" |
bddc9ab0 | 40 | #include "compat.h" |
30460aeb | 41 | #include "key.h" |
42 | #include "hostfile.h" | |
3c0ef626 | 43 | #include "auth.h" |
3c0ef626 | 44 | #include "dispatch.h" |
3c0ef626 | 45 | #include "pathnames.h" |
dfddba3d | 46 | #include "buffer.h" |
3c0ef626 | 47 | |
5598e598 | 48 | #ifdef GSSAPI |
49 | #include "ssh-gss.h" | |
50 | #endif | |
30460aeb | 51 | #include "monitor_wrap.h" |
5598e598 | 52 | |
3c0ef626 | 53 | /* import */ |
54 | extern ServerOptions options; | |
55 | extern u_char *session_id2; | |
7cac2b65 | 56 | extern u_int session_id2_len; |
dfddba3d | 57 | extern Buffer loginmsg; |
3c0ef626 | 58 | |
44a053a3 | 59 | /* methods */ |
60 | ||
61 | extern Authmethod method_none; | |
44a053a3 | 62 | extern Authmethod method_pubkey; |
63 | extern Authmethod method_passwd; | |
64 | extern Authmethod method_kbdint; | |
65 | extern Authmethod method_hostbased; | |
db870295 | 66 | #ifdef GSSAPI |
67 | extern Authmethod method_external; | |
fe4ad273 | 68 | extern Authmethod method_gsskeyex; |
db870295 | 69 | extern Authmethod method_gssapi; |
540d72c3 | 70 | extern Authmethod method_gssapi_compat; |
db870295 | 71 | #endif |
44a053a3 | 72 | |
73 | Authmethod *authmethods[] = { | |
74 | &method_none, | |
44a053a3 | 75 | &method_pubkey, |
7cac2b65 | 76 | #ifdef GSSAPI |
fe4ad273 | 77 | &method_gsskeyex, |
540d72c3 | 78 | &method_external, |
7cac2b65 | 79 | &method_gssapi, |
540d72c3 | 80 | &method_gssapi_compat, |
7cac2b65 | 81 | #endif |
44a053a3 | 82 | &method_passwd, |
83 | &method_kbdint, | |
84 | &method_hostbased, | |
85 | NULL | |
3c0ef626 | 86 | }; |
87 | ||
88 | /* protocol */ | |
89 | ||
1e608e42 | 90 | static void input_service_request(int, u_int32_t, void *); |
91 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 92 | |
93 | /* helper */ | |
94 | static Authmethod *authmethod_lookup(const char *); | |
95 | static char *authmethods_get(void); | |
510132b6 | 96 | int user_key_allowed(struct passwd *, Key *); |
3c0ef626 | 97 | |
3c0ef626 | 98 | /* |
99 | * loop until authctxt->success == TRUE | |
100 | */ | |
101 | ||
540d72c3 | 102 | void |
103 | do_authentication2(Authctxt *authctxt) | |
3c0ef626 | 104 | { |
3c0ef626 | 105 | /* challenge-response is implemented via keyboard interactive */ |
106 | if (options.challenge_response_authentication) | |
107 | options.kbd_interactive_authentication = 1; | |
3c0ef626 | 108 | |
1e608e42 | 109 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 110 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
111 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
3c0ef626 | 112 | } |
113 | ||
30460aeb | 114 | /*ARGSUSED*/ |
3c0ef626 | 115 | static void |
1e608e42 | 116 | input_service_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 117 | { |
118 | Authctxt *authctxt = ctxt; | |
119 | u_int len; | |
d03f4262 | 120 | int acceptit = 0; |
3c0ef626 | 121 | char *service = packet_get_string(&len); |
1e608e42 | 122 | packet_check_eom(); |
3c0ef626 | 123 | |
124 | if (authctxt == NULL) | |
125 | fatal("input_service_request: no authctxt"); | |
126 | ||
127 | if (strcmp(service, "ssh-userauth") == 0) { | |
128 | if (!authctxt->success) { | |
d03f4262 | 129 | acceptit = 1; |
3c0ef626 | 130 | /* now we can handle user-auth requests */ |
131 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
132 | } | |
133 | } | |
134 | /* XXX all other service requests are denied */ | |
135 | ||
d03f4262 | 136 | if (acceptit) { |
3c0ef626 | 137 | packet_start(SSH2_MSG_SERVICE_ACCEPT); |
138 | packet_put_cstring(service); | |
139 | packet_send(); | |
140 | packet_write_wait(); | |
141 | } else { | |
142 | debug("bad service request %s", service); | |
143 | packet_disconnect("bad service request %s", service); | |
144 | } | |
145 | xfree(service); | |
146 | } | |
147 | ||
30460aeb | 148 | /*ARGSUSED*/ |
3c0ef626 | 149 | static void |
1e608e42 | 150 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 151 | { |
152 | Authctxt *authctxt = ctxt; | |
153 | Authmethod *m = NULL; | |
154 | char *user, *service, *method, *style = NULL; | |
155 | int authenticated = 0; | |
156 | ||
157 | if (authctxt == NULL) | |
158 | fatal("input_userauth_request: no authctxt"); | |
159 | ||
160 | user = packet_get_string(NULL); | |
161 | service = packet_get_string(NULL); | |
162 | method = packet_get_string(NULL); | |
73a68d83 | 163 | |
305d07c0 | 164 | #ifdef GSSAPI |
8f3eb4db | 165 | if (user[0] == '\0') { |
b8e8844a | 166 | debug("received empty username for %s", method); |
fe4ad273 | 167 | if (strcmp(method, "external-keyx") == 0 || |
168 | strcmp(method, "gssapi-keyex") == 0) { | |
b8e8844a | 169 | char *lname = NULL; |
170 | PRIVSEP(ssh_gssapi_localname(&lname)); | |
171 | if (lname && lname[0] != '\0') { | |
172 | xfree(user); | |
173 | user = lname; | |
174 | debug("set username to %s from gssapi context", user); | |
9ec9d5ad | 175 | } else { |
b8e8844a | 176 | debug("failed to set username from gssapi context"); |
d9e17760 | 177 | packet_send_debug("failed to set username from gssapi context"); |
b8e8844a | 178 | } |
b59afbfe | 179 | } |
180 | } | |
181 | #endif | |
73a68d83 | 182 | |
b8e8844a | 183 | debug("userauth-request for user %s service %s method %s", |
8f3eb4db | 184 | user[0] ? user : "<implicit>", service, method); |
3c0ef626 | 185 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); |
186 | ||
187 | if ((style = strchr(user, ':')) != NULL) | |
188 | *style++ = 0; | |
189 | ||
781f72b9 | 190 | /* If first time or username changed or implicit username, |
191 | setup/reset authentication context. */ | |
192 | if ((authctxt->attempt++ == 0) || | |
193 | (strcmp(user, authctxt->user) != 0) || | |
194 | (strcmp(user, "") == 0)) { | |
b59afbfe | 195 | if (authctxt->user) { |
196 | xfree(authctxt->user); | |
197 | authctxt->user = NULL; | |
198 | } | |
b809a58e | 199 | authctxt->valid = 0; |
b8e8844a | 200 | #ifdef GSSAPI |
9ec9d5ad | 201 | /* If we're going to set the username based on the |
202 | GSSAPI context later, then wait until then to | |
8f3eb4db | 203 | verify it. Just put in placeholders for now. */ |
204 | if ((strcmp(user, "") == 0) && | |
205 | ((strcmp(method, "gssapi") == 0) || | |
206 | (strcmp(method, "gssapi-with-mic") == 0))) { | |
207 | authctxt->pw = fakepw(); | |
208 | authctxt->user = xstrdup(user); | |
209 | } else { | |
b8e8844a | 210 | #endif |
510132b6 | 211 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
12a403af | 212 | authctxt->user = xstrdup(user); |
510132b6 | 213 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { |
3c0ef626 | 214 | authctxt->valid = 1; |
215 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
3c0ef626 | 216 | } else { |
7e82606e | 217 | logit("input_userauth_request: invalid user %s", user); |
7cac2b65 | 218 | authctxt->pw = fakepw(); |
dfddba3d | 219 | #ifdef SSH_AUDIT_EVENTS |
220 | PRIVSEP(audit_event(SSH_INVALID_USER)); | |
3c0ef626 | 221 | #endif |
222 | } | |
b8e8844a | 223 | #ifdef GSSAPI |
9ec9d5ad | 224 | } /* endif for setting username based on GSSAPI context */ |
08822d99 | 225 | #endif |
226 | #ifdef USE_PAM | |
227 | if (options.use_pam) | |
228 | PRIVSEP(start_pam(authctxt)); | |
b8e8844a | 229 | #endif |
7e82606e | 230 | setproctitle("%s%s", authctxt->valid ? user : "unknown", |
510132b6 | 231 | use_privsep ? " [net]" : ""); |
b809a58e | 232 | #ifdef GSSAPI |
88ca8dfd | 233 | if (authctxt->attempt == 1) { |
b809a58e | 234 | #endif |
235 | authctxt->service = xstrdup(service); | |
236 | authctxt->style = style ? xstrdup(style) : NULL; | |
237 | if (use_privsep) | |
510132b6 | 238 | mm_inform_authserv(service, style); |
b809a58e | 239 | #ifdef GSSAPI |
240 | } /* if (authctxt->attempt == 1) */ | |
241 | #endif | |
885ffc2b | 242 | } |
243 | if (strcmp(service, authctxt->service) != 0) { | |
67b84e65 | 244 | packet_disconnect("Change of service not allowed: " |
245 | "(%s,%s) -> (%s,%s)", | |
246 | authctxt->user, authctxt->service, user, service); | |
3c0ef626 | 247 | } |
248 | /* reset state */ | |
1e608e42 | 249 | auth2_challenge_stop(authctxt); |
5598e598 | 250 | |
251 | #ifdef GSSAPI | |
1e608e42 | 252 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
253 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
5598e598 | 254 | #endif |
255 | ||
3c0ef626 | 256 | authctxt->postponed = 0; |
fe4ad273 | 257 | authctxt->server_caused_failure = 0; |
3c0ef626 | 258 | |
259 | /* try to authenticate user */ | |
260 | m = authmethod_lookup(method); | |
261 | if (m != NULL) { | |
262 | debug2("input_userauth_request: try method %s", method); | |
263 | authenticated = m->userauth(authctxt); | |
264 | } | |
265 | userauth_finish(authctxt, authenticated, method); | |
266 | ||
267 | xfree(service); | |
268 | xfree(user); | |
269 | xfree(method); | |
270 | } | |
271 | ||
272 | void | |
273 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
274 | { | |
275 | char *methods; | |
276 | ||
277 | if (!authctxt->valid && authenticated) | |
278 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
279 | authctxt->user); | |
280 | ||
281 | /* Special handling for root */ | |
bfe49944 | 282 | if (authenticated && authctxt->pw->pw_uid == 0 && |
dfddba3d | 283 | !auth_root_allowed(method)) { |
3c0ef626 | 284 | authenticated = 0; |
dfddba3d | 285 | #ifdef SSH_AUDIT_EVENTS |
286 | PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); | |
287 | #endif | |
288 | } | |
3c0ef626 | 289 | |
290 | #ifdef USE_PAM | |
dfddba3d | 291 | if (options.use_pam && authenticated) { |
292 | if (!PRIVSEP(do_pam_account())) { | |
293 | /* if PAM returned a message, send it to the user */ | |
294 | if (buffer_len(&loginmsg) > 0) { | |
295 | buffer_append(&loginmsg, "\0", 1); | |
296 | userauth_send_banner(buffer_ptr(&loginmsg)); | |
297 | packet_write_wait(); | |
298 | } | |
299 | fatal("Access denied for user %s by PAM account " | |
2ce0bfe4 | 300 | "configuration", authctxt->user); |
dfddba3d | 301 | } |
302 | } | |
7cac2b65 | 303 | #endif |
3c0ef626 | 304 | |
d03f4262 | 305 | #ifdef _UNICOS |
306 | if (authenticated && cray_access_denied(authctxt->user)) { | |
307 | authenticated = 0; | |
308 | fatal("Access denied for user %s.",authctxt->user); | |
309 | } | |
310 | #endif /* _UNICOS */ | |
311 | ||
3c0ef626 | 312 | /* Log before sending the reply */ |
313 | auth_log(authctxt, authenticated, method, " ssh2"); | |
314 | ||
315 | if (authctxt->postponed) | |
316 | return; | |
317 | ||
318 | /* XXX todo: check if multiple auth methods are needed */ | |
319 | if (authenticated == 1) { | |
320 | /* turn off userauth */ | |
1e608e42 | 321 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
3c0ef626 | 322 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
323 | packet_send(); | |
324 | packet_write_wait(); | |
325 | /* now we can break out */ | |
326 | authctxt->success = 1; | |
327 | } else { | |
fe4ad273 | 328 | /* Dont count server configuration issues against the client */ |
329 | if (!authctxt->server_caused_failure && | |
330 | authctxt->failures++ > options.max_authtries) { | |
dfddba3d | 331 | #ifdef SSH_AUDIT_EVENTS |
332 | PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); | |
333 | #endif | |
3c0ef626 | 334 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
dfddba3d | 335 | } |
3c0ef626 | 336 | methods = authmethods_get(); |
337 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
338 | packet_put_cstring(methods); | |
339 | packet_put_char(0); /* XXX partial success, unused */ | |
340 | packet_send(); | |
341 | packet_write_wait(); | |
342 | xfree(methods); | |
343 | } | |
344 | } | |
345 | ||
3c0ef626 | 346 | #define DELIM "," |
347 | ||
348 | static char * | |
349 | authmethods_get(void) | |
350 | { | |
1e608e42 | 351 | Buffer b; |
3c0ef626 | 352 | char *list; |
44a053a3 | 353 | int i; |
3c0ef626 | 354 | |
1e608e42 | 355 | buffer_init(&b); |
44a053a3 | 356 | for (i = 0; authmethods[i] != NULL; i++) { |
357 | if (strcmp(authmethods[i]->name, "none") == 0) | |
3c0ef626 | 358 | continue; |
44a053a3 | 359 | if (authmethods[i]->enabled != NULL && |
360 | *(authmethods[i]->enabled) != 0) { | |
1e608e42 | 361 | if (buffer_len(&b) > 0) |
362 | buffer_append(&b, ",", 1); | |
44a053a3 | 363 | buffer_append(&b, authmethods[i]->name, |
364 | strlen(authmethods[i]->name)); | |
3c0ef626 | 365 | } |
366 | } | |
1e608e42 | 367 | buffer_append(&b, "\0", 1); |
368 | list = xstrdup(buffer_ptr(&b)); | |
369 | buffer_free(&b); | |
3c0ef626 | 370 | return list; |
371 | } | |
372 | ||
373 | static Authmethod * | |
374 | authmethod_lookup(const char *name) | |
375 | { | |
44a053a3 | 376 | int i; |
377 | ||
3c0ef626 | 378 | if (name != NULL) |
44a053a3 | 379 | for (i = 0; authmethods[i] != NULL; i++) |
380 | if (authmethods[i]->enabled != NULL && | |
381 | *(authmethods[i]->enabled) != 0 && | |
382 | strcmp(name, authmethods[i]->name) == 0) | |
383 | return authmethods[i]; | |
384 | debug2("Unrecognized authentication method name: %s", | |
385 | name ? name : "NULL"); | |
3c0ef626 | 386 | return NULL; |
387 | } |