2 * Copyright (c) 2000 Damien Miller. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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.
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.
38 #define NEW_AUTHTOK_MSG \
39 "Warning: Your password has expired, please change it now"
41 static int do_pam_conversation(int num_msg, const struct pam_message **msg,
42 struct pam_response **resp, void *appdata_ptr);
44 /* module-local variables */
45 static struct pam_conv conv = {
49 static char *__pam_msg = NULL;
50 static pam_handle_t *__pamh = NULL;
51 static const char *__pampasswd = NULL;
53 /* states for do_pam_conversation() */
54 enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN;
55 /* remember whether pam_acct_mgmt() returned PAM_NEWAUTHTOK_REQD */
56 static int password_change_required = 0;
57 /* remember whether the last pam_authenticate() succeeded or not */
58 static int was_authenticated = 0;
60 /* Remember what has been initialised */
61 static int session_opened = 0;
62 static int creds_set = 0;
64 /* accessor which allows us to switch conversation structs according to
65 * the authentication method being used */
66 void do_pam_set_conv(struct pam_conv *conv)
68 pam_set_item(__pamh, PAM_CONV, conv);
71 /* start an authentication run */
72 int do_pam_authenticate(int flags)
74 int retval = pam_authenticate(__pamh, flags);
75 was_authenticated = (retval == PAM_SUCCESS);
80 * PAM conversation function.
81 * There are two states this can run in.
83 * INITIAL_LOGIN mode simply feeds the password from the client into
84 * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output
85 * messages with into __pam_msg. This is used during initial
86 * authentication to bypass the normal PAM password prompt.
88 * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase(prompt, 1)
89 * and outputs messages to stderr. This mode is used if pam_chauthtok()
90 * is called to update expired passwords.
92 static int do_pam_conversation(int num_msg, const struct pam_message **msg,
93 struct pam_response **resp, void *appdata_ptr)
95 struct pam_response *reply;
99 /* PAM will free this later */
100 reply = malloc(num_msg * sizeof(*reply));
104 for (count = 0; count < num_msg; count++) {
105 if (pamstate == INITIAL_LOGIN) {
107 * We can't use stdio yet, queue messages for
110 switch(PAM_MSG_MEMBER(msg, count, msg_style)) {
111 case PAM_PROMPT_ECHO_ON:
114 case PAM_PROMPT_ECHO_OFF:
115 if (__pampasswd == NULL) {
119 reply[count].resp = xstrdup(__pampasswd);
120 reply[count].resp_retcode = PAM_SUCCESS;
124 if ((*msg)[count].msg != NULL) {
125 message_cat(&__pam_msg,
126 PAM_MSG_MEMBER(msg, count, msg));
128 reply[count].resp = xstrdup("");
129 reply[count].resp_retcode = PAM_SUCCESS;
137 * stdio is connected, so interact directly
139 switch(PAM_MSG_MEMBER(msg, count, msg_style)) {
140 case PAM_PROMPT_ECHO_ON:
141 fputs(PAM_MSG_MEMBER(msg, count, msg), stderr);
142 fgets(buf, sizeof(buf), stdin);
143 reply[count].resp = xstrdup(buf);
144 reply[count].resp_retcode = PAM_SUCCESS;
146 case PAM_PROMPT_ECHO_OFF:
147 reply[count].resp = xstrdup(
148 read_passphrase(PAM_MSG_MEMBER(msg, count,
150 reply[count].resp_retcode = PAM_SUCCESS;
154 if ((*msg)[count].msg != NULL)
155 fprintf(stderr, "%s\n",
156 PAM_MSG_MEMBER(msg, count, msg));
157 reply[count].resp = xstrdup("");
158 reply[count].resp_retcode = PAM_SUCCESS;
172 /* Called at exit to cleanly shutdown PAM */
173 void do_pam_cleanup_proc(void *context)
177 if (__pamh && session_opened) {
178 pam_retval = pam_close_session(__pamh, 0);
179 if (pam_retval != PAM_SUCCESS)
180 log("Cannot close PAM session[%d]: %.200s",
181 pam_retval, PAM_STRERROR(__pamh, pam_retval));
184 if (__pamh && creds_set) {
185 pam_retval = pam_setcred(__pamh, PAM_DELETE_CRED);
186 if (pam_retval != PAM_SUCCESS)
187 debug("Cannot delete credentials[%d]: %.200s",
188 pam_retval, PAM_STRERROR(__pamh, pam_retval));
192 pam_retval = pam_end(__pamh, pam_retval);
193 if (pam_retval != PAM_SUCCESS)
194 log("Cannot release PAM authentication[%d]: %.200s",
195 pam_retval, PAM_STRERROR(__pamh, pam_retval));
199 /* Attempt password authentation using PAM */
200 int auth_pam_password(struct passwd *pw, const char *password)
202 extern ServerOptions options;
205 do_pam_set_conv(&conv);
207 /* deny if no user. */
210 if (pw->pw_uid == 0 && options.permit_root_login == 2)
212 if (*password == '\0' && options.permit_empty_passwd == 0)
215 __pampasswd = password;
217 pamstate = INITIAL_LOGIN;
218 pam_retval = do_pam_authenticate(0);
219 if (pam_retval == PAM_SUCCESS) {
220 debug("PAM Password authentication accepted for "
221 "user \"%.100s\"", pw->pw_name);
224 debug("PAM Password authentication for \"%.100s\" "
225 "failed[%d]: %s", pw->pw_name, pam_retval,
226 PAM_STRERROR(__pamh, pam_retval));
231 /* Do account management using PAM */
232 int do_pam_account(char *username, char *remote_user)
236 do_pam_set_conv(&conv);
239 debug("PAM setting ruser to \"%.200s\"", remote_user);
240 pam_retval = pam_set_item(__pamh, PAM_RUSER, remote_user);
241 if (pam_retval != PAM_SUCCESS)
242 fatal("PAM set ruser failed[%d]: %.200s", pam_retval,
243 PAM_STRERROR(__pamh, pam_retval));
246 pam_retval = pam_acct_mgmt(__pamh, 0);
247 switch (pam_retval) {
249 /* This is what we want */
251 case PAM_NEW_AUTHTOK_REQD:
252 message_cat(&__pam_msg, NEW_AUTHTOK_MSG);
253 /* flag that password change is necessary */
254 password_change_required = 1;
257 log("PAM rejected by account configuration[%d]: "
258 "%.200s", pam_retval, PAM_STRERROR(__pamh,
266 /* Do PAM-specific session initialisation */
267 void do_pam_session(char *username, const char *ttyname)
271 do_pam_set_conv(&conv);
273 if (ttyname != NULL) {
274 debug("PAM setting tty to \"%.200s\"", ttyname);
275 pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname);
276 if (pam_retval != PAM_SUCCESS)
277 fatal("PAM set tty failed[%d]: %.200s",
278 pam_retval, PAM_STRERROR(__pamh, pam_retval));
281 pam_retval = pam_open_session(__pamh, 0);
282 if (pam_retval != PAM_SUCCESS)
283 fatal("PAM session setup failed[%d]: %.200s",
284 pam_retval, PAM_STRERROR(__pamh, pam_retval));
289 /* Set PAM credentials */
290 void do_pam_setcred(void)
294 do_pam_set_conv(&conv);
296 debug("PAM establishing creds");
297 pam_retval = pam_setcred(__pamh, PAM_ESTABLISH_CRED);
298 if (pam_retval != PAM_SUCCESS) {
299 if (was_authenticated)
300 fatal("PAM setcred failed[%d]: %.200s",
301 pam_retval, PAM_STRERROR(__pamh, pam_retval));
303 debug("PAM setcred failed[%d]: %.200s",
304 pam_retval, PAM_STRERROR(__pamh, pam_retval));
309 /* accessor function for file scope static variable */
310 int is_pam_password_change_required(void)
312 return password_change_required;
316 * Have user change authentication token if pam_acct_mgmt() indicated
317 * it was expired. This needs to be called after an interactive
318 * session is established and the user's pty is connected to
319 * stdin/stout/stderr.
321 void do_pam_chauthtok(void)
325 do_pam_set_conv(&conv);
327 if (password_change_required) {
329 /* XXX: should we really loop forever? */
331 pam_retval = pam_chauthtok(__pamh,
332 PAM_CHANGE_EXPIRED_AUTHTOK);
333 if (pam_retval != PAM_SUCCESS)
334 log("PAM pam_chauthtok failed[%d]: %.200s",
335 pam_retval, PAM_STRERROR(__pamh, pam_retval));
336 } while (pam_retval != PAM_SUCCESS);
340 /* Cleanly shutdown PAM */
341 void finish_pam(void)
343 do_pam_cleanup_proc(NULL);
344 fatal_remove_cleanup(&do_pam_cleanup_proc, NULL);
347 /* Start PAM authentication for specified account */
348 void start_pam(const char *user)
351 extern ServerOptions options;
353 debug("Starting up PAM with username \"%.200s\"", user);
355 pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh);
357 if (pam_retval != PAM_SUCCESS)
358 fatal("PAM initialisation failed[%d]: %.200s",
359 pam_retval, PAM_STRERROR(__pamh, pam_retval));
361 debug("PAM setting rhost to \"%.200s\"",
362 get_canonical_hostname(options.reverse_mapping_check));
363 pam_retval = pam_set_item(__pamh, PAM_RHOST,
364 get_canonical_hostname(options.reverse_mapping_check));
365 if (pam_retval != PAM_SUCCESS)
366 fatal("PAM set rhost failed[%d]: %.200s", pam_retval,
367 PAM_STRERROR(__pamh, pam_retval));
368 #ifdef PAM_TTY_KLUDGE
370 * Some PAM modules (e.g. pam_time) require a TTY to operate,
371 * and will fail in various stupid ways if they don't get one.
372 * sshd doesn't set the tty until too late in the auth process and may
373 * not even need one (for tty-less connections)
374 * Kludge: Set a fake PAM_TTY
376 pam_retval = pam_set_item(__pamh, PAM_TTY, "ssh");
377 if (pam_retval != PAM_SUCCESS)
378 fatal("PAM set tty failed[%d]: %.200s",
379 pam_retval, PAM_STRERROR(__pamh, pam_retval));
380 #endif /* PAM_TTY_KLUDGE */
382 fatal_add_cleanup(&do_pam_cleanup_proc, NULL);
385 /* Return list of PAM enviornment strings */
386 char **fetch_pam_environment(void)
388 #ifdef HAVE_PAM_GETENVLIST
389 return(pam_getenvlist(__pamh));
390 #else /* HAVE_PAM_GETENVLIST */
392 #endif /* HAVE_PAM_GETENVLIST */
395 /* Print any messages that have been generated during authentication */
396 /* or account checking to stderr */
397 void print_pam_messages(void)
399 if (__pam_msg != NULL)
400 fputs(__pam_msg, stderr);
403 /* Append a message to buffer */
404 void message_cat(char **p, const char *a)
412 size_t len = strlen(*p);
414 *p = xrealloc(*p, new_len + len + 2);
417 *p = cp = xmalloc(new_len + 2);
419 memcpy(cp, a, new_len);
421 cp[new_len + 1] = '\0';