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3c0ef626 | 1 | /* |
2 | * Copyright (c) 2000 Damien Miller. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | ||
27 | #ifdef USE_PAM | |
3c0ef626 | 28 | #include "xmalloc.h" |
29 | #include "log.h" | |
350391c5 | 30 | #include "auth.h" |
d03f4262 | 31 | #include "auth-options.h" |
3c0ef626 | 32 | #include "auth-pam.h" |
33 | #include "servconf.h" | |
34 | #include "canohost.h" | |
35 | #include "readpass.h" | |
36 | ||
37 | extern char *__progname; | |
38 | ||
d03f4262 | 39 | extern int use_privsep; |
40 | ||
3c0ef626 | 41 | RCSID("$Id$"); |
42 | ||
43 | #define NEW_AUTHTOK_MSG \ | |
d03f4262 | 44 | "Warning: Your password has expired, please change it now." |
45 | #define NEW_AUTHTOK_MSG_PRIVSEP \ | |
46 | "Your password has expired, the session cannot proceed." | |
3c0ef626 | 47 | |
48 | static int do_pam_conversation(int num_msg, const struct pam_message **msg, | |
49 | struct pam_response **resp, void *appdata_ptr); | |
50 | ||
51 | /* module-local variables */ | |
52 | static struct pam_conv conv = { | |
d03f4262 | 53 | (int (*)())do_pam_conversation, |
3c0ef626 | 54 | NULL |
55 | }; | |
56 | static char *__pam_msg = NULL; | |
57 | static pam_handle_t *__pamh = NULL; | |
58 | static const char *__pampasswd = NULL; | |
59 | ||
60 | /* states for do_pam_conversation() */ | |
61 | enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN; | |
d03f4262 | 62 | /* remember whether pam_acct_mgmt() returned PAM_NEW_AUTHTOK_REQD */ |
3c0ef626 | 63 | static int password_change_required = 0; |
64 | /* remember whether the last pam_authenticate() succeeded or not */ | |
65 | static int was_authenticated = 0; | |
66 | ||
67 | /* Remember what has been initialised */ | |
68 | static int session_opened = 0; | |
69 | static int creds_set = 0; | |
70 | ||
71 | /* accessor which allows us to switch conversation structs according to | |
72 | * the authentication method being used */ | |
73 | void do_pam_set_conv(struct pam_conv *conv) | |
74 | { | |
75 | pam_set_item(__pamh, PAM_CONV, conv); | |
76 | } | |
77 | ||
78 | /* start an authentication run */ | |
79 | int do_pam_authenticate(int flags) | |
80 | { | |
81 | int retval = pam_authenticate(__pamh, flags); | |
82 | was_authenticated = (retval == PAM_SUCCESS); | |
83 | return retval; | |
84 | } | |
85 | ||
86 | /* | |
87 | * PAM conversation function. | |
88 | * There are two states this can run in. | |
89 | * | |
90 | * INITIAL_LOGIN mode simply feeds the password from the client into | |
91 | * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output | |
92 | * messages with into __pam_msg. This is used during initial | |
93 | * authentication to bypass the normal PAM password prompt. | |
94 | * | |
95 | * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase() | |
96 | * and outputs messages to stderr. This mode is used if pam_chauthtok() | |
97 | * is called to update expired passwords. | |
98 | */ | |
99 | static int do_pam_conversation(int num_msg, const struct pam_message **msg, | |
100 | struct pam_response **resp, void *appdata_ptr) | |
101 | { | |
102 | struct pam_response *reply; | |
103 | int count; | |
104 | char buf[1024]; | |
105 | ||
106 | /* PAM will free this later */ | |
d03f4262 | 107 | reply = xmalloc(num_msg * sizeof(*reply)); |
3c0ef626 | 108 | |
109 | for (count = 0; count < num_msg; count++) { | |
110 | if (pamstate == INITIAL_LOGIN) { | |
111 | /* | |
112 | * We can't use stdio yet, queue messages for | |
113 | * printing later | |
114 | */ | |
115 | switch(PAM_MSG_MEMBER(msg, count, msg_style)) { | |
116 | case PAM_PROMPT_ECHO_ON: | |
d03f4262 | 117 | xfree(reply); |
3c0ef626 | 118 | return PAM_CONV_ERR; |
119 | case PAM_PROMPT_ECHO_OFF: | |
120 | if (__pampasswd == NULL) { | |
d03f4262 | 121 | xfree(reply); |
3c0ef626 | 122 | return PAM_CONV_ERR; |
123 | } | |
124 | reply[count].resp = xstrdup(__pampasswd); | |
125 | reply[count].resp_retcode = PAM_SUCCESS; | |
126 | break; | |
127 | case PAM_ERROR_MSG: | |
128 | case PAM_TEXT_INFO: | |
d03f4262 | 129 | if (PAM_MSG_MEMBER(msg, count, msg) != NULL) { |
3c0ef626 | 130 | message_cat(&__pam_msg, |
131 | PAM_MSG_MEMBER(msg, count, msg)); | |
132 | } | |
133 | reply[count].resp = xstrdup(""); | |
134 | reply[count].resp_retcode = PAM_SUCCESS; | |
135 | break; | |
136 | default: | |
d03f4262 | 137 | xfree(reply); |
3c0ef626 | 138 | return PAM_CONV_ERR; |
139 | } | |
140 | } else { | |
141 | /* | |
142 | * stdio is connected, so interact directly | |
143 | */ | |
144 | switch(PAM_MSG_MEMBER(msg, count, msg_style)) { | |
145 | case PAM_PROMPT_ECHO_ON: | |
146 | fputs(PAM_MSG_MEMBER(msg, count, msg), stderr); | |
147 | fgets(buf, sizeof(buf), stdin); | |
148 | reply[count].resp = xstrdup(buf); | |
149 | reply[count].resp_retcode = PAM_SUCCESS; | |
150 | break; | |
151 | case PAM_PROMPT_ECHO_OFF: | |
152 | reply[count].resp = | |
153 | read_passphrase(PAM_MSG_MEMBER(msg, count, | |
154 | msg), RP_ALLOW_STDIN); | |
155 | reply[count].resp_retcode = PAM_SUCCESS; | |
156 | break; | |
157 | case PAM_ERROR_MSG: | |
158 | case PAM_TEXT_INFO: | |
d03f4262 | 159 | if (PAM_MSG_MEMBER(msg, count, msg) != NULL) |
3c0ef626 | 160 | fprintf(stderr, "%s\n", |
161 | PAM_MSG_MEMBER(msg, count, msg)); | |
162 | reply[count].resp = xstrdup(""); | |
163 | reply[count].resp_retcode = PAM_SUCCESS; | |
164 | break; | |
165 | default: | |
d03f4262 | 166 | xfree(reply); |
3c0ef626 | 167 | return PAM_CONV_ERR; |
168 | } | |
169 | } | |
170 | } | |
171 | ||
172 | *resp = reply; | |
173 | ||
174 | return PAM_SUCCESS; | |
175 | } | |
176 | ||
177 | /* Called at exit to cleanly shutdown PAM */ | |
178 | void do_pam_cleanup_proc(void *context) | |
179 | { | |
180 | int pam_retval = PAM_SUCCESS; | |
181 | ||
182 | if (__pamh && session_opened) { | |
183 | pam_retval = pam_close_session(__pamh, 0); | |
184 | if (pam_retval != PAM_SUCCESS) | |
185 | log("Cannot close PAM session[%d]: %.200s", | |
186 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
187 | } | |
188 | ||
189 | if (__pamh && creds_set) { | |
190 | pam_retval = pam_setcred(__pamh, PAM_DELETE_CRED); | |
191 | if (pam_retval != PAM_SUCCESS) | |
192 | debug("Cannot delete credentials[%d]: %.200s", | |
193 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
194 | } | |
195 | ||
196 | if (__pamh) { | |
197 | pam_retval = pam_end(__pamh, pam_retval); | |
198 | if (pam_retval != PAM_SUCCESS) | |
199 | log("Cannot release PAM authentication[%d]: %.200s", | |
200 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
201 | } | |
202 | } | |
203 | ||
256cb466 | 204 | /* Attempt password authentication using PAM */ |
350391c5 | 205 | int auth_pam_password(Authctxt *authctxt, const char *password) |
3c0ef626 | 206 | { |
207 | extern ServerOptions options; | |
208 | int pam_retval; | |
350391c5 | 209 | struct passwd *pw = authctxt->pw; |
3c0ef626 | 210 | |
211 | do_pam_set_conv(&conv); | |
212 | ||
3c0ef626 | 213 | __pampasswd = password; |
214 | ||
215 | pamstate = INITIAL_LOGIN; | |
216 | pam_retval = do_pam_authenticate( | |
217 | options.permit_empty_passwd == 0 ? PAM_DISALLOW_NULL_AUTHTOK : 0); | |
256cb466 | 218 | if (pam_retval == PAM_SUCCESS && pw) { |
219 | debug("PAM password authentication accepted for " | |
220 | "%.100s", pw->pw_name); | |
3c0ef626 | 221 | return 1; |
222 | } else { | |
256cb466 | 223 | debug("PAM password authentication failed for " |
224 | "%.100s: %s", pw ? pw->pw_name : "an illegal user", | |
3c0ef626 | 225 | PAM_STRERROR(__pamh, pam_retval)); |
226 | return 0; | |
227 | } | |
228 | } | |
229 | ||
230 | /* Do account management using PAM */ | |
231 | int do_pam_account(char *username, char *remote_user) | |
232 | { | |
233 | int pam_retval; | |
234 | ||
235 | do_pam_set_conv(&conv); | |
236 | ||
237 | if (remote_user) { | |
238 | debug("PAM setting ruser to \"%.200s\"", remote_user); | |
239 | pam_retval = pam_set_item(__pamh, PAM_RUSER, remote_user); | |
240 | if (pam_retval != PAM_SUCCESS) | |
241 | fatal("PAM set ruser failed[%d]: %.200s", pam_retval, | |
242 | PAM_STRERROR(__pamh, pam_retval)); | |
243 | } | |
244 | ||
245 | pam_retval = pam_acct_mgmt(__pamh, 0); | |
350391c5 | 246 | debug2("pam_acct_mgmt() = %d", pam_retval); |
3c0ef626 | 247 | switch (pam_retval) { |
248 | case PAM_SUCCESS: | |
249 | /* This is what we want */ | |
250 | break; | |
350391c5 | 251 | #if 0 |
3c0ef626 | 252 | case PAM_NEW_AUTHTOK_REQD: |
d03f4262 | 253 | message_cat(&__pam_msg, use_privsep ? |
254 | NEW_AUTHTOK_MSG_PRIVSEP : NEW_AUTHTOK_MSG); | |
3c0ef626 | 255 | /* flag that password change is necessary */ |
256 | password_change_required = 1; | |
d03f4262 | 257 | /* disallow other functionality for now */ |
258 | no_port_forwarding_flag |= 2; | |
259 | no_agent_forwarding_flag |= 2; | |
260 | no_x11_forwarding_flag |= 2; | |
3c0ef626 | 261 | break; |
350391c5 | 262 | #endif |
3c0ef626 | 263 | default: |
264 | log("PAM rejected by account configuration[%d]: " | |
265 | "%.200s", pam_retval, PAM_STRERROR(__pamh, | |
266 | pam_retval)); | |
267 | return(0); | |
268 | } | |
269 | ||
270 | return(1); | |
271 | } | |
272 | ||
273 | /* Do PAM-specific session initialisation */ | |
274 | void do_pam_session(char *username, const char *ttyname) | |
275 | { | |
276 | int pam_retval; | |
277 | ||
278 | do_pam_set_conv(&conv); | |
279 | ||
280 | if (ttyname != NULL) { | |
281 | debug("PAM setting tty to \"%.200s\"", ttyname); | |
282 | pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname); | |
283 | if (pam_retval != PAM_SUCCESS) | |
284 | fatal("PAM set tty failed[%d]: %.200s", | |
285 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
286 | } | |
287 | ||
288 | pam_retval = pam_open_session(__pamh, 0); | |
289 | if (pam_retval != PAM_SUCCESS) | |
290 | fatal("PAM session setup failed[%d]: %.200s", | |
291 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
292 | ||
293 | session_opened = 1; | |
294 | } | |
295 | ||
296 | /* Set PAM credentials */ | |
297 | void do_pam_setcred(int init) | |
298 | { | |
299 | int pam_retval; | |
300 | ||
350391c5 | 301 | if (__pamh == NULL) |
302 | return; | |
303 | ||
3c0ef626 | 304 | do_pam_set_conv(&conv); |
305 | ||
306 | debug("PAM establishing creds"); | |
307 | pam_retval = pam_setcred(__pamh, | |
308 | init ? PAM_ESTABLISH_CRED : PAM_REINITIALIZE_CRED); | |
309 | if (pam_retval != PAM_SUCCESS) { | |
310 | if (was_authenticated) | |
311 | fatal("PAM setcred failed[%d]: %.200s", | |
312 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
313 | else | |
314 | debug("PAM setcred failed[%d]: %.200s", | |
315 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
316 | } else | |
317 | creds_set = 1; | |
318 | } | |
319 | ||
320 | /* accessor function for file scope static variable */ | |
321 | int is_pam_password_change_required(void) | |
322 | { | |
323 | return password_change_required; | |
324 | } | |
325 | ||
326 | /* | |
327 | * Have user change authentication token if pam_acct_mgmt() indicated | |
328 | * it was expired. This needs to be called after an interactive | |
329 | * session is established and the user's pty is connected to | |
d03f4262 | 330 | * stdin/stdout/stderr. |
3c0ef626 | 331 | */ |
332 | void do_pam_chauthtok(void) | |
333 | { | |
334 | int pam_retval; | |
335 | ||
336 | do_pam_set_conv(&conv); | |
337 | ||
338 | if (password_change_required) { | |
d03f4262 | 339 | if (use_privsep) |
340 | fatal("Password changing is currently unsupported" | |
341 | " with privilege separation"); | |
3c0ef626 | 342 | pamstate = OTHER; |
343 | pam_retval = pam_chauthtok(__pamh, PAM_CHANGE_EXPIRED_AUTHTOK); | |
344 | if (pam_retval != PAM_SUCCESS) | |
345 | fatal("PAM pam_chauthtok failed[%d]: %.200s", | |
346 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
d03f4262 | 347 | #if 0 |
348 | /* XXX: This would need to be done in the parent process, | |
349 | * but there's currently no way to pass such request. */ | |
350 | no_port_forwarding_flag &= ~2; | |
351 | no_agent_forwarding_flag &= ~2; | |
352 | no_x11_forwarding_flag &= ~2; | |
353 | if (!no_port_forwarding_flag && options.allow_tcp_forwarding) | |
354 | channel_permit_all_opens(); | |
355 | #endif | |
3c0ef626 | 356 | } |
357 | } | |
358 | ||
359 | /* Cleanly shutdown PAM */ | |
360 | void finish_pam(void) | |
361 | { | |
362 | do_pam_cleanup_proc(NULL); | |
363 | fatal_remove_cleanup(&do_pam_cleanup_proc, NULL); | |
364 | } | |
365 | ||
366 | /* Start PAM authentication for specified account */ | |
367 | void start_pam(const char *user) | |
368 | { | |
369 | int pam_retval; | |
370 | extern ServerOptions options; | |
371 | extern u_int utmp_len; | |
372 | const char *rhost; | |
373 | ||
374 | debug("Starting up PAM with username \"%.200s\"", user); | |
375 | ||
376 | pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh); | |
377 | ||
378 | if (pam_retval != PAM_SUCCESS) | |
379 | fatal("PAM initialisation failed[%d]: %.200s", | |
380 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
381 | ||
e9702f7d | 382 | rhost = get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping); |
3c0ef626 | 383 | debug("PAM setting rhost to \"%.200s\"", rhost); |
384 | ||
385 | pam_retval = pam_set_item(__pamh, PAM_RHOST, rhost); | |
386 | if (pam_retval != PAM_SUCCESS) | |
387 | fatal("PAM set rhost failed[%d]: %.200s", pam_retval, | |
388 | PAM_STRERROR(__pamh, pam_retval)); | |
389 | #ifdef PAM_TTY_KLUDGE | |
390 | /* | |
391 | * Some PAM modules (e.g. pam_time) require a TTY to operate, | |
392 | * and will fail in various stupid ways if they don't get one. | |
393 | * sshd doesn't set the tty until too late in the auth process and may | |
394 | * not even need one (for tty-less connections) | |
395 | * Kludge: Set a fake PAM_TTY | |
396 | */ | |
397 | pam_retval = pam_set_item(__pamh, PAM_TTY, "NODEVssh"); | |
398 | if (pam_retval != PAM_SUCCESS) | |
399 | fatal("PAM set tty failed[%d]: %.200s", | |
400 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); | |
401 | #endif /* PAM_TTY_KLUDGE */ | |
402 | ||
403 | fatal_add_cleanup(&do_pam_cleanup_proc, NULL); | |
404 | } | |
405 | ||
d03f4262 | 406 | /* Return list of PAM environment strings */ |
3c0ef626 | 407 | char **fetch_pam_environment(void) |
408 | { | |
409 | #ifdef HAVE_PAM_GETENVLIST | |
410 | return(pam_getenvlist(__pamh)); | |
411 | #else /* HAVE_PAM_GETENVLIST */ | |
412 | return(NULL); | |
413 | #endif /* HAVE_PAM_GETENVLIST */ | |
414 | } | |
415 | ||
23987cb8 | 416 | void free_pam_environment(char **env) |
417 | { | |
418 | int i; | |
419 | ||
420 | if (env != NULL) { | |
421 | for (i = 0; env[i] != NULL; i++) | |
422 | xfree(env[i]); | |
423 | } | |
424 | } | |
425 | ||
5598e598 | 426 | /* Set a PAM environment string. We need to do this so that the session |
427 | * modules can handle things like Kerberos/GSI credentials that appear | |
428 | * during the ssh authentication process. | |
429 | */ | |
430 | ||
431 | int do_pam_putenv(char *name, char *value) { | |
432 | char *compound; | |
433 | int ret=1; | |
905081a4 | 434 | |
435 | #ifdef HAVE_PAM_PUTENV | |
5598e598 | 436 | compound=xmalloc(strlen(name)+strlen(value)+2); |
437 | if (compound) { | |
438 | sprintf(compound,"%s=%s",name,value); | |
439 | ret=pam_putenv(__pamh,compound); | |
440 | xfree(compound); | |
441 | } | |
905081a4 | 442 | #endif |
5598e598 | 443 | return(ret); |
444 | } | |
445 | ||
3c0ef626 | 446 | /* Print any messages that have been generated during authentication */ |
447 | /* or account checking to stderr */ | |
448 | void print_pam_messages(void) | |
449 | { | |
450 | if (__pam_msg != NULL) | |
451 | fputs(__pam_msg, stderr); | |
452 | } | |
453 | ||
454 | /* Append a message to buffer */ | |
455 | void message_cat(char **p, const char *a) | |
456 | { | |
457 | char *cp; | |
458 | size_t new_len; | |
459 | ||
460 | new_len = strlen(a); | |
461 | ||
462 | if (*p) { | |
463 | size_t len = strlen(*p); | |
464 | ||
465 | *p = xrealloc(*p, new_len + len + 2); | |
466 | cp = *p + len; | |
467 | } else | |
468 | *p = cp = xmalloc(new_len + 2); | |
469 | ||
470 | memcpy(cp, a, new_len); | |
471 | cp[new_len] = '\n'; | |
472 | cp[new_len + 1] = '\0'; | |
473 | } | |
474 | ||
475 | #endif /* USE_PAM */ |