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 |
---|
28 | #include "ssh.h" |
---|
29 | #include "xmalloc.h" |
---|
30 | #include "log.h" |
---|
31 | #include "auth-pam.h" |
---|
32 | #include "servconf.h" |
---|
33 | #include "canohost.h" |
---|
34 | #include "readpass.h" |
---|
35 | |
---|
36 | extern char *__progname; |
---|
37 | |
---|
38 | RCSID("$Id: auth-pam.c,v 1.2 2002-02-15 19:46:58 zacheiss Exp $"); |
---|
39 | |
---|
40 | #define NEW_AUTHTOK_MSG \ |
---|
41 | "Warning: Your password has expired, please change it now" |
---|
42 | |
---|
43 | static int do_pam_conversation(int num_msg, const struct pam_message **msg, |
---|
44 | struct pam_response **resp, void *appdata_ptr); |
---|
45 | |
---|
46 | /* module-local variables */ |
---|
47 | static struct pam_conv conv = { |
---|
48 | do_pam_conversation, |
---|
49 | NULL |
---|
50 | }; |
---|
51 | static char *__pam_msg = NULL; |
---|
52 | static pam_handle_t *__pamh = NULL; |
---|
53 | static const char *__pampasswd = NULL; |
---|
54 | |
---|
55 | /* states for do_pam_conversation() */ |
---|
56 | enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN; |
---|
57 | /* remember whether pam_acct_mgmt() returned PAM_NEWAUTHTOK_REQD */ |
---|
58 | static int password_change_required = 0; |
---|
59 | /* remember whether the last pam_authenticate() succeeded or not */ |
---|
60 | static int was_authenticated = 0; |
---|
61 | |
---|
62 | /* Remember what has been initialised */ |
---|
63 | static int session_opened = 0; |
---|
64 | static int creds_set = 0; |
---|
65 | |
---|
66 | /* accessor which allows us to switch conversation structs according to |
---|
67 | * the authentication method being used */ |
---|
68 | void do_pam_set_conv(struct pam_conv *conv) |
---|
69 | { |
---|
70 | pam_set_item(__pamh, PAM_CONV, conv); |
---|
71 | } |
---|
72 | |
---|
73 | /* start an authentication run */ |
---|
74 | int do_pam_authenticate(int flags) |
---|
75 | { |
---|
76 | int retval = pam_authenticate(__pamh, flags); |
---|
77 | was_authenticated = (retval == PAM_SUCCESS); |
---|
78 | return retval; |
---|
79 | } |
---|
80 | |
---|
81 | /* |
---|
82 | * PAM conversation function. |
---|
83 | * There are two states this can run in. |
---|
84 | * |
---|
85 | * INITIAL_LOGIN mode simply feeds the password from the client into |
---|
86 | * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output |
---|
87 | * messages with into __pam_msg. This is used during initial |
---|
88 | * authentication to bypass the normal PAM password prompt. |
---|
89 | * |
---|
90 | * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase() |
---|
91 | * and outputs messages to stderr. This mode is used if pam_chauthtok() |
---|
92 | * is called to update expired passwords. |
---|
93 | */ |
---|
94 | static int do_pam_conversation(int num_msg, const struct pam_message **msg, |
---|
95 | struct pam_response **resp, void *appdata_ptr) |
---|
96 | { |
---|
97 | struct pam_response *reply; |
---|
98 | int count; |
---|
99 | char buf[1024]; |
---|
100 | |
---|
101 | /* PAM will free this later */ |
---|
102 | reply = malloc(num_msg * sizeof(*reply)); |
---|
103 | if (reply == NULL) |
---|
104 | return PAM_CONV_ERR; |
---|
105 | |
---|
106 | for (count = 0; count < num_msg; count++) { |
---|
107 | if (pamstate == INITIAL_LOGIN) { |
---|
108 | /* |
---|
109 | * We can't use stdio yet, queue messages for |
---|
110 | * printing later |
---|
111 | */ |
---|
112 | switch(PAM_MSG_MEMBER(msg, count, msg_style)) { |
---|
113 | case PAM_PROMPT_ECHO_ON: |
---|
114 | free(reply); |
---|
115 | return PAM_CONV_ERR; |
---|
116 | case PAM_PROMPT_ECHO_OFF: |
---|
117 | if (__pampasswd == NULL) { |
---|
118 | free(reply); |
---|
119 | return PAM_CONV_ERR; |
---|
120 | } |
---|
121 | reply[count].resp = xstrdup(__pampasswd); |
---|
122 | reply[count].resp_retcode = PAM_SUCCESS; |
---|
123 | break; |
---|
124 | case PAM_ERROR_MSG: |
---|
125 | case PAM_TEXT_INFO: |
---|
126 | if ((*msg)[count].msg != NULL) { |
---|
127 | message_cat(&__pam_msg, |
---|
128 | PAM_MSG_MEMBER(msg, count, msg)); |
---|
129 | } |
---|
130 | reply[count].resp = xstrdup(""); |
---|
131 | reply[count].resp_retcode = PAM_SUCCESS; |
---|
132 | break; |
---|
133 | default: |
---|
134 | free(reply); |
---|
135 | return PAM_CONV_ERR; |
---|
136 | } |
---|
137 | } else { |
---|
138 | /* |
---|
139 | * stdio is connected, so interact directly |
---|
140 | */ |
---|
141 | switch(PAM_MSG_MEMBER(msg, count, msg_style)) { |
---|
142 | case PAM_PROMPT_ECHO_ON: |
---|
143 | fputs(PAM_MSG_MEMBER(msg, count, msg), stderr); |
---|
144 | fgets(buf, sizeof(buf), stdin); |
---|
145 | reply[count].resp = xstrdup(buf); |
---|
146 | reply[count].resp_retcode = PAM_SUCCESS; |
---|
147 | break; |
---|
148 | case PAM_PROMPT_ECHO_OFF: |
---|
149 | reply[count].resp = |
---|
150 | read_passphrase(PAM_MSG_MEMBER(msg, count, |
---|
151 | msg), RP_ALLOW_STDIN); |
---|
152 | reply[count].resp_retcode = PAM_SUCCESS; |
---|
153 | break; |
---|
154 | case PAM_ERROR_MSG: |
---|
155 | case PAM_TEXT_INFO: |
---|
156 | if ((*msg)[count].msg != NULL) |
---|
157 | fprintf(stderr, "%s\n", |
---|
158 | PAM_MSG_MEMBER(msg, count, msg)); |
---|
159 | reply[count].resp = xstrdup(""); |
---|
160 | reply[count].resp_retcode = PAM_SUCCESS; |
---|
161 | break; |
---|
162 | default: |
---|
163 | free(reply); |
---|
164 | return PAM_CONV_ERR; |
---|
165 | } |
---|
166 | } |
---|
167 | } |
---|
168 | |
---|
169 | *resp = reply; |
---|
170 | |
---|
171 | return PAM_SUCCESS; |
---|
172 | } |
---|
173 | |
---|
174 | /* Called at exit to cleanly shutdown PAM */ |
---|
175 | void do_pam_cleanup_proc(void *context) |
---|
176 | { |
---|
177 | int pam_retval = PAM_SUCCESS; |
---|
178 | |
---|
179 | if (__pamh && session_opened) { |
---|
180 | pam_retval = pam_close_session(__pamh, 0); |
---|
181 | if (pam_retval != PAM_SUCCESS) |
---|
182 | log("Cannot close PAM session[%d]: %.200s", |
---|
183 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
184 | } |
---|
185 | |
---|
186 | if (__pamh && creds_set) { |
---|
187 | pam_retval = pam_setcred(__pamh, PAM_DELETE_CRED); |
---|
188 | if (pam_retval != PAM_SUCCESS) |
---|
189 | debug("Cannot delete credentials[%d]: %.200s", |
---|
190 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
191 | } |
---|
192 | |
---|
193 | if (__pamh) { |
---|
194 | pam_retval = pam_end(__pamh, pam_retval); |
---|
195 | if (pam_retval != PAM_SUCCESS) |
---|
196 | log("Cannot release PAM authentication[%d]: %.200s", |
---|
197 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
198 | } |
---|
199 | } |
---|
200 | |
---|
201 | /* Attempt password authentation using PAM */ |
---|
202 | int auth_pam_password(struct passwd *pw, const char *password) |
---|
203 | { |
---|
204 | extern ServerOptions options; |
---|
205 | int pam_retval; |
---|
206 | |
---|
207 | do_pam_set_conv(&conv); |
---|
208 | |
---|
209 | /* deny if no user. */ |
---|
210 | if (pw == NULL) |
---|
211 | return 0; |
---|
212 | if (pw->pw_uid == 0 && options.permit_root_login == PERMIT_NO_PASSWD) |
---|
213 | return 0; |
---|
214 | if (*password == '\0' && options.permit_empty_passwd == 0) |
---|
215 | return 0; |
---|
216 | |
---|
217 | __pampasswd = password; |
---|
218 | |
---|
219 | pamstate = INITIAL_LOGIN; |
---|
220 | pam_retval = do_pam_authenticate( |
---|
221 | options.permit_empty_passwd == 0 ? PAM_DISALLOW_NULL_AUTHTOK : 0); |
---|
222 | if (pam_retval == PAM_SUCCESS) { |
---|
223 | debug("PAM Password authentication accepted for " |
---|
224 | "user \"%.100s\"", pw->pw_name); |
---|
225 | return 1; |
---|
226 | } else { |
---|
227 | debug("PAM Password authentication for \"%.100s\" " |
---|
228 | "failed[%d]: %s", pw->pw_name, pam_retval, |
---|
229 | PAM_STRERROR(__pamh, pam_retval)); |
---|
230 | return 0; |
---|
231 | } |
---|
232 | } |
---|
233 | |
---|
234 | /* Do account management using PAM */ |
---|
235 | int do_pam_account(char *username, char *remote_user) |
---|
236 | { |
---|
237 | int pam_retval; |
---|
238 | |
---|
239 | do_pam_set_conv(&conv); |
---|
240 | |
---|
241 | if (remote_user) { |
---|
242 | debug("PAM setting ruser to \"%.200s\"", remote_user); |
---|
243 | pam_retval = pam_set_item(__pamh, PAM_RUSER, remote_user); |
---|
244 | if (pam_retval != PAM_SUCCESS) |
---|
245 | fatal("PAM set ruser failed[%d]: %.200s", pam_retval, |
---|
246 | PAM_STRERROR(__pamh, pam_retval)); |
---|
247 | } |
---|
248 | |
---|
249 | pam_retval = pam_acct_mgmt(__pamh, 0); |
---|
250 | switch (pam_retval) { |
---|
251 | case PAM_SUCCESS: |
---|
252 | /* This is what we want */ |
---|
253 | break; |
---|
254 | case PAM_NEW_AUTHTOK_REQD: |
---|
255 | message_cat(&__pam_msg, NEW_AUTHTOK_MSG); |
---|
256 | /* flag that password change is necessary */ |
---|
257 | password_change_required = 1; |
---|
258 | break; |
---|
259 | default: |
---|
260 | log("PAM rejected by account configuration[%d]: " |
---|
261 | "%.200s", pam_retval, PAM_STRERROR(__pamh, |
---|
262 | pam_retval)); |
---|
263 | return(0); |
---|
264 | } |
---|
265 | |
---|
266 | return(1); |
---|
267 | } |
---|
268 | |
---|
269 | /* Do PAM-specific session initialisation */ |
---|
270 | void do_pam_session(char *username, const char *ttyname) |
---|
271 | { |
---|
272 | int pam_retval; |
---|
273 | |
---|
274 | do_pam_set_conv(&conv); |
---|
275 | |
---|
276 | if (ttyname != NULL) { |
---|
277 | debug("PAM setting tty to \"%.200s\"", ttyname); |
---|
278 | pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname); |
---|
279 | if (pam_retval != PAM_SUCCESS) |
---|
280 | fatal("PAM set tty failed[%d]: %.200s", |
---|
281 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
282 | } |
---|
283 | |
---|
284 | pam_retval = pam_open_session(__pamh, 0); |
---|
285 | if (pam_retval != PAM_SUCCESS) |
---|
286 | fatal("PAM session setup failed[%d]: %.200s", |
---|
287 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
288 | |
---|
289 | session_opened = 1; |
---|
290 | } |
---|
291 | |
---|
292 | /* Set PAM credentials */ |
---|
293 | void do_pam_setcred(int init) |
---|
294 | { |
---|
295 | int pam_retval; |
---|
296 | |
---|
297 | do_pam_set_conv(&conv); |
---|
298 | |
---|
299 | debug("PAM establishing creds"); |
---|
300 | pam_retval = pam_setcred(__pamh, |
---|
301 | init ? PAM_ESTABLISH_CRED : PAM_REINITIALIZE_CRED); |
---|
302 | if (pam_retval != PAM_SUCCESS) { |
---|
303 | if (was_authenticated) |
---|
304 | fatal("PAM setcred failed[%d]: %.200s", |
---|
305 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
306 | else |
---|
307 | debug("PAM setcred failed[%d]: %.200s", |
---|
308 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
309 | } else |
---|
310 | creds_set = 1; |
---|
311 | } |
---|
312 | |
---|
313 | /* accessor function for file scope static variable */ |
---|
314 | int is_pam_password_change_required(void) |
---|
315 | { |
---|
316 | return password_change_required; |
---|
317 | } |
---|
318 | |
---|
319 | /* |
---|
320 | * Have user change authentication token if pam_acct_mgmt() indicated |
---|
321 | * it was expired. This needs to be called after an interactive |
---|
322 | * session is established and the user's pty is connected to |
---|
323 | * stdin/stout/stderr. |
---|
324 | */ |
---|
325 | void do_pam_chauthtok(void) |
---|
326 | { |
---|
327 | int pam_retval; |
---|
328 | |
---|
329 | do_pam_set_conv(&conv); |
---|
330 | |
---|
331 | if (password_change_required) { |
---|
332 | pamstate = OTHER; |
---|
333 | pam_retval = pam_chauthtok(__pamh, PAM_CHANGE_EXPIRED_AUTHTOK); |
---|
334 | if (pam_retval != PAM_SUCCESS) |
---|
335 | fatal("PAM pam_chauthtok failed[%d]: %.200s", |
---|
336 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
337 | } |
---|
338 | } |
---|
339 | |
---|
340 | /* Cleanly shutdown PAM */ |
---|
341 | void finish_pam(void) |
---|
342 | { |
---|
343 | do_pam_cleanup_proc(NULL); |
---|
344 | fatal_remove_cleanup(&do_pam_cleanup_proc, NULL); |
---|
345 | } |
---|
346 | |
---|
347 | /* Start PAM authentication for specified account */ |
---|
348 | void start_pam(const char *user) |
---|
349 | { |
---|
350 | int pam_retval; |
---|
351 | extern ServerOptions options; |
---|
352 | extern u_int utmp_len; |
---|
353 | const char *rhost; |
---|
354 | |
---|
355 | debug("Starting up PAM with username \"%.200s\"", user); |
---|
356 | |
---|
357 | pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh); |
---|
358 | |
---|
359 | if (pam_retval != PAM_SUCCESS) |
---|
360 | fatal("PAM initialisation failed[%d]: %.200s", |
---|
361 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
362 | |
---|
363 | rhost = get_remote_name_or_ip(utmp_len, options.reverse_mapping_check); |
---|
364 | debug("PAM setting rhost to \"%.200s\"", rhost); |
---|
365 | |
---|
366 | pam_retval = pam_set_item(__pamh, PAM_RHOST, rhost); |
---|
367 | if (pam_retval != PAM_SUCCESS) |
---|
368 | fatal("PAM set rhost failed[%d]: %.200s", pam_retval, |
---|
369 | PAM_STRERROR(__pamh, pam_retval)); |
---|
370 | #ifdef PAM_TTY_KLUDGE |
---|
371 | /* |
---|
372 | * Some PAM modules (e.g. pam_time) require a TTY to operate, |
---|
373 | * and will fail in various stupid ways if they don't get one. |
---|
374 | * sshd doesn't set the tty until too late in the auth process and may |
---|
375 | * not even need one (for tty-less connections) |
---|
376 | * Kludge: Set a fake PAM_TTY |
---|
377 | */ |
---|
378 | pam_retval = pam_set_item(__pamh, PAM_TTY, "NODEVssh"); |
---|
379 | if (pam_retval != PAM_SUCCESS) |
---|
380 | fatal("PAM set tty failed[%d]: %.200s", |
---|
381 | pam_retval, PAM_STRERROR(__pamh, pam_retval)); |
---|
382 | #endif /* PAM_TTY_KLUDGE */ |
---|
383 | |
---|
384 | fatal_add_cleanup(&do_pam_cleanup_proc, NULL); |
---|
385 | } |
---|
386 | |
---|
387 | /* Return list of PAM enviornment strings */ |
---|
388 | char **fetch_pam_environment(void) |
---|
389 | { |
---|
390 | #ifdef HAVE_PAM_GETENVLIST |
---|
391 | return(pam_getenvlist(__pamh)); |
---|
392 | #else /* HAVE_PAM_GETENVLIST */ |
---|
393 | return(NULL); |
---|
394 | #endif /* HAVE_PAM_GETENVLIST */ |
---|
395 | } |
---|
396 | |
---|
397 | /* Set a PAM environment string. We need to do this so that the session |
---|
398 | * modules can handle things like Kerberos/GSI credentials that appear |
---|
399 | * during the ssh authentication process. |
---|
400 | */ |
---|
401 | |
---|
402 | int do_pam_putenv(char *name, char *value) { |
---|
403 | char *compound; |
---|
404 | int ret=1; |
---|
405 | |
---|
406 | compound=xmalloc(strlen(name)+strlen(value)+2); |
---|
407 | if (compound) { |
---|
408 | sprintf(compound,"%s=%s",name,value); |
---|
409 | ret=pam_putenv(__pamh,compound); |
---|
410 | xfree(compound); |
---|
411 | } |
---|
412 | return(ret); |
---|
413 | } |
---|
414 | |
---|
415 | /* Print any messages that have been generated during authentication */ |
---|
416 | /* or account checking to stderr */ |
---|
417 | void print_pam_messages(void) |
---|
418 | { |
---|
419 | if (__pam_msg != NULL) |
---|
420 | fputs(__pam_msg, stderr); |
---|
421 | } |
---|
422 | |
---|
423 | /* Append a message to buffer */ |
---|
424 | void message_cat(char **p, const char *a) |
---|
425 | { |
---|
426 | char *cp; |
---|
427 | size_t new_len; |
---|
428 | |
---|
429 | new_len = strlen(a); |
---|
430 | |
---|
431 | if (*p) { |
---|
432 | size_t len = strlen(*p); |
---|
433 | |
---|
434 | *p = xrealloc(*p, new_len + len + 2); |
---|
435 | cp = *p + len; |
---|
436 | } else |
---|
437 | *p = cp = xmalloc(new_len + 2); |
---|
438 | |
---|
439 | memcpy(cp, a, new_len); |
---|
440 | cp[new_len] = '\n'; |
---|
441 | cp[new_len + 1] = '\0'; |
---|
442 | } |
---|
443 | |
---|
444 | #endif /* USE_PAM */ |
---|