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a5c9cd31 | 1 | /* |
09564242 | 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. | |
09564242 | 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. | |
a5c9cd31 | 23 | */ |
24 | ||
25 | #include "includes.h" | |
26 | ||
27 | #ifdef USE_PAM | |
28 | #include "ssh.h" | |
29 | #include "xmalloc.h" | |
42f11eb2 | 30 | #include "log.h" |
a5c9cd31 | 31 | #include "servconf.h" |
42f11eb2 | 32 | #include "canohost.h" |
33 | #include "readpass.h" | |
a5c9cd31 | 34 | |
35 | RCSID("$Id$"); | |
36 | ||
5daf7064 | 37 | #define NEW_AUTHTOK_MSG \ |
ad55cd03 | 38 | "Warning: Your password has expired, please change it now" |
5daf7064 | 39 | |
a5c9cd31 | 40 | /* Callbacks */ |
41 | static int pamconv(int num_msg, const struct pam_message **msg, | |
42 | struct pam_response **resp, void *appdata_ptr); | |
43 | void pam_cleanup_proc(void *context); | |
5daf7064 | 44 | void pam_msg_cat(const char *msg); |
a5c9cd31 | 45 | |
46 | /* module-local variables */ | |
47 | static struct pam_conv conv = { | |
48 | pamconv, | |
49 | NULL | |
50 | }; | |
ad55cd03 | 51 | static pam_handle_t *pamh = NULL; |
a5c9cd31 | 52 | static const char *pampasswd = NULL; |
5daf7064 | 53 | static char *pam_msg = NULL; |
a5c9cd31 | 54 | |
ad55cd03 | 55 | /* states for pamconv() */ |
8c9fe09e | 56 | enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN; |
ad55cd03 | 57 | /* remember whether pam_acct_mgmt() returned PAM_NEWAUTHTOK_REQD */ |
58 | static int password_change_required = 0; | |
8c9fe09e | 59 | /* remember whether the last pam_authenticate() succeeded or not */ |
60 | static int was_authenticated = 0; | |
61 | ||
62 | /* accessor which allows us to switch conversation structs according to | |
63 | * the authentication method being used */ | |
64 | void pam_set_conv(struct pam_conv *conv) | |
65 | { | |
66 | pam_set_item(pamh, PAM_CONV, conv); | |
67 | } | |
68 | ||
69 | /* start an authentication run */ | |
70 | int do_pam_authenticate(int flags) | |
71 | { | |
72 | int retval = pam_authenticate(pamh, flags); | |
73 | was_authenticated = (retval == PAM_SUCCESS); | |
74 | return retval; | |
75 | } | |
ad55cd03 | 76 | |
77 | /* | |
78 | * PAM conversation function. | |
79 | * There are two states this can run in. | |
80 | * | |
81 | * INITIAL_LOGIN mode simply feeds the password from the client into | |
82 | * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output | |
83 | * messages with pam_msg_cat(). This is used during initial | |
84 | * authentication to bypass the normal PAM password prompt. | |
85 | * | |
86 | * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase(prompt, 1) | |
87 | * and outputs messages to stderr. This mode is used if pam_chauthtok() | |
88 | * is called to update expired passwords. | |
89 | */ | |
a5c9cd31 | 90 | static int pamconv(int num_msg, const struct pam_message **msg, |
91 | struct pam_response **resp, void *appdata_ptr) | |
92 | { | |
93 | struct pam_response *reply; | |
94 | int count; | |
ad55cd03 | 95 | char buf[1024]; |
a5c9cd31 | 96 | |
97 | /* PAM will free this later */ | |
98 | reply = malloc(num_msg * sizeof(*reply)); | |
99 | if (reply == NULL) | |
100 | return PAM_CONV_ERR; | |
101 | ||
ad55cd03 | 102 | for (count = 0; count < num_msg; count++) { |
adeebd37 | 103 | switch(PAM_MSG_MEMBER(msg, count, msg_style)) { |
ad55cd03 | 104 | case PAM_PROMPT_ECHO_ON: |
71dfaf1c | 105 | if (pamstate == INITIAL_LOGIN) { |
106 | free(reply); | |
107 | return PAM_CONV_ERR; | |
108 | } else { | |
adeebd37 | 109 | fputs(PAM_MSG_MEMBER(msg, count, msg), stderr); |
71dfaf1c | 110 | fgets(buf, sizeof(buf), stdin); |
111 | reply[count].resp = xstrdup(buf); | |
112 | reply[count].resp_retcode = PAM_SUCCESS; | |
113 | break; | |
114 | } | |
a5c9cd31 | 115 | case PAM_PROMPT_ECHO_OFF: |
ad55cd03 | 116 | if (pamstate == INITIAL_LOGIN) { |
117 | if (pampasswd == NULL) { | |
118 | free(reply); | |
119 | return PAM_CONV_ERR; | |
120 | } | |
121 | reply[count].resp = xstrdup(pampasswd); | |
71dfaf1c | 122 | } else { |
123 | reply[count].resp = | |
adeebd37 | 124 | xstrdup(read_passphrase(PAM_MSG_MEMBER(msg, count, msg), 1)); |
71dfaf1c | 125 | } |
a5c9cd31 | 126 | reply[count].resp_retcode = PAM_SUCCESS; |
a5c9cd31 | 127 | break; |
ad55cd03 | 128 | case PAM_ERROR_MSG: |
a5c9cd31 | 129 | case PAM_TEXT_INFO: |
ad55cd03 | 130 | if ((*msg)[count].msg != NULL) { |
131 | if (pamstate == INITIAL_LOGIN) | |
adeebd37 | 132 | pam_msg_cat(PAM_MSG_MEMBER(msg, count, msg)); |
ad55cd03 | 133 | else { |
adeebd37 | 134 | fputs(PAM_MSG_MEMBER(msg, count, msg), stderr); |
ad55cd03 | 135 | fputs("\n", stderr); |
136 | } | |
137 | } | |
a5c9cd31 | 138 | reply[count].resp = xstrdup(""); |
ad55cd03 | 139 | reply[count].resp_retcode = PAM_SUCCESS; |
a5c9cd31 | 140 | break; |
a5c9cd31 | 141 | default: |
142 | free(reply); | |
143 | return PAM_CONV_ERR; | |
144 | } | |
145 | } | |
146 | ||
147 | *resp = reply; | |
148 | ||
149 | return PAM_SUCCESS; | |
150 | } | |
151 | ||
152 | /* Called at exit to cleanly shutdown PAM */ | |
153 | void pam_cleanup_proc(void *context) | |
154 | { | |
155 | int pam_retval; | |
156 | ||
157 | if (pamh != NULL) | |
158 | { | |
ad55cd03 | 159 | pam_retval = pam_close_session(pamh, 0); |
a5c9cd31 | 160 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 161 | log("Cannot close PAM session[%d]: %.200s", |
162 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
a5c9cd31 | 163 | } |
164 | ||
ad55cd03 | 165 | pam_retval = pam_setcred(pamh, PAM_DELETE_CRED); |
a5c9cd31 | 166 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 167 | debug("Cannot delete credentials[%d]: %.200s", |
168 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
a5c9cd31 | 169 | } |
170 | ||
ad55cd03 | 171 | pam_retval = pam_end(pamh, pam_retval); |
a5c9cd31 | 172 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 173 | log("Cannot release PAM authentication[%d]: %.200s", |
174 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
a5c9cd31 | 175 | } |
176 | } | |
177 | } | |
178 | ||
179 | /* Attempt password authentation using PAM */ | |
180 | int auth_pam_password(struct passwd *pw, const char *password) | |
181 | { | |
182 | extern ServerOptions options; | |
183 | int pam_retval; | |
184 | ||
8c9fe09e | 185 | pam_set_conv(&conv); |
186 | ||
a5c9cd31 | 187 | /* deny if no user. */ |
188 | if (pw == NULL) | |
189 | return 0; | |
190 | if (pw->pw_uid == 0 && options.permit_root_login == 2) | |
191 | return 0; | |
192 | if (*password == '\0' && options.permit_empty_passwd == 0) | |
193 | return 0; | |
194 | ||
195 | pampasswd = password; | |
196 | ||
ad55cd03 | 197 | pamstate = INITIAL_LOGIN; |
8c9fe09e | 198 | pam_retval = do_pam_authenticate(0); |
a5c9cd31 | 199 | if (pam_retval == PAM_SUCCESS) { |
5daf7064 | 200 | debug("PAM Password authentication accepted for user \"%.100s\"", |
201 | pw->pw_name); | |
a5c9cd31 | 202 | return 1; |
203 | } else { | |
ebd782f7 | 204 | debug("PAM Password authentication for \"%.100s\" failed[%d]: %s", |
205 | pw->pw_name, pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
a5c9cd31 | 206 | return 0; |
207 | } | |
208 | } | |
209 | ||
210 | /* Do account management using PAM */ | |
211 | int do_pam_account(char *username, char *remote_user) | |
212 | { | |
213 | int pam_retval; | |
5daf7064 | 214 | |
a5c9cd31 | 215 | debug("PAM setting rhost to \"%.200s\"", get_canonical_hostname()); |
ad55cd03 | 216 | pam_retval = pam_set_item(pamh, PAM_RHOST, |
a5c9cd31 | 217 | get_canonical_hostname()); |
218 | if (pam_retval != PAM_SUCCESS) { | |
ebd782f7 | 219 | fatal("PAM set rhost failed[%d]: %.200s", |
220 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
a5c9cd31 | 221 | } |
222 | ||
223 | if (remote_user != NULL) { | |
224 | debug("PAM setting ruser to \"%.200s\"", remote_user); | |
ad55cd03 | 225 | pam_retval = pam_set_item(pamh, PAM_RUSER, remote_user); |
a5c9cd31 | 226 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 227 | fatal("PAM set ruser failed[%d]: %.200s", |
228 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
a5c9cd31 | 229 | } |
230 | } | |
231 | ||
ad55cd03 | 232 | pam_retval = pam_acct_mgmt(pamh, 0); |
5daf7064 | 233 | switch (pam_retval) { |
234 | case PAM_SUCCESS: | |
235 | /* This is what we want */ | |
236 | break; | |
237 | case PAM_NEW_AUTHTOK_REQD: | |
238 | pam_msg_cat(NEW_AUTHTOK_MSG); | |
ad55cd03 | 239 | /* flag that password change is necessary */ |
240 | password_change_required = 1; | |
5daf7064 | 241 | break; |
242 | default: | |
ebd782f7 | 243 | log("PAM rejected by account configuration[%d]: %.200s", |
244 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
5daf7064 | 245 | return(0); |
a5c9cd31 | 246 | } |
247 | ||
248 | return(1); | |
249 | } | |
250 | ||
251 | /* Do PAM-specific session initialisation */ | |
fd094f49 | 252 | void do_pam_session(char *username, const char *ttyname) |
a5c9cd31 | 253 | { |
254 | int pam_retval; | |
255 | ||
256 | if (ttyname != NULL) { | |
257 | debug("PAM setting tty to \"%.200s\"", ttyname); | |
ad55cd03 | 258 | pam_retval = pam_set_item(pamh, PAM_TTY, ttyname); |
5daf7064 | 259 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 260 | fatal("PAM set tty failed[%d]: %.200s", |
261 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
5daf7064 | 262 | } |
a5c9cd31 | 263 | } |
264 | ||
ad55cd03 | 265 | pam_retval = pam_open_session(pamh, 0); |
5daf7064 | 266 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 267 | fatal("PAM session setup failed[%d]: %.200s", |
268 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
5daf7064 | 269 | } |
a5c9cd31 | 270 | } |
271 | ||
272 | /* Set PAM credentials */ | |
a815d7a3 | 273 | void do_pam_setcred(void) |
a5c9cd31 | 274 | { |
275 | int pam_retval; | |
276 | ||
277 | debug("PAM establishing creds"); | |
ad55cd03 | 278 | pam_retval = pam_setcred(pamh, PAM_ESTABLISH_CRED); |
5daf7064 | 279 | if (pam_retval != PAM_SUCCESS) { |
8c9fe09e | 280 | if(was_authenticated) { |
281 | fatal("PAM setcred failed[%d]: %.200s", | |
282 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
283 | } else { | |
284 | debug("PAM setcred failed[%d]: %.200s", | |
285 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
286 | } | |
ad55cd03 | 287 | } |
288 | } | |
289 | ||
2919e060 | 290 | /* accessor function for file scope static variable */ |
291 | int pam_password_change_required(void) | |
292 | { | |
293 | return password_change_required; | |
294 | } | |
295 | ||
ad55cd03 | 296 | /* |
297 | * Have user change authentication token if pam_acct_mgmt() indicated | |
298 | * it was expired. This needs to be called after an interactive | |
299 | * session is established and the user's pty is connected to | |
300 | * stdin/stout/stderr. | |
301 | */ | |
a815d7a3 | 302 | void do_pam_chauthtok(void) |
ad55cd03 | 303 | { |
304 | int pam_retval; | |
305 | ||
306 | if (password_change_required) { | |
307 | pamstate = OTHER; | |
ebd782f7 | 308 | /* |
309 | * XXX: should we really loop forever? | |
310 | */ | |
ad55cd03 | 311 | do { |
312 | pam_retval = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK); | |
ebd782f7 | 313 | if (pam_retval != PAM_SUCCESS) { |
314 | log("PAM pam_chauthtok failed[%d]: %.200s", | |
315 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
316 | } | |
ad55cd03 | 317 | } while (pam_retval != PAM_SUCCESS); |
5daf7064 | 318 | } |
a5c9cd31 | 319 | } |
320 | ||
321 | /* Cleanly shutdown PAM */ | |
322 | void finish_pam(void) | |
323 | { | |
324 | pam_cleanup_proc(NULL); | |
325 | fatal_remove_cleanup(&pam_cleanup_proc, NULL); | |
326 | } | |
327 | ||
328 | /* Start PAM authentication for specified account */ | |
04fc7a67 | 329 | void start_pam(const char *user) |
a5c9cd31 | 330 | { |
331 | int pam_retval; | |
332 | ||
04fc7a67 | 333 | debug("Starting up PAM with username \"%.200s\"", user); |
a5c9cd31 | 334 | |
04fc7a67 | 335 | pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &pamh); |
a5c9cd31 | 336 | |
5daf7064 | 337 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 338 | fatal("PAM initialisation failed[%d]: %.200s", |
339 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
5daf7064 | 340 | } |
ae543aaa | 341 | |
a8545c6c | 342 | #ifdef PAM_TTY_KLUDGE |
ae543aaa | 343 | /* |
344 | * Some PAM modules (e.g. pam_time) require a TTY to operate, | |
345 | * and will fail in various stupid ways if they don't get one. | |
346 | * sshd doesn't set the tty until too late in the auth process and may | |
347 | * not even need one (for tty-less connections) | |
348 | * Kludge: Set a fake PAM_TTY | |
349 | */ | |
ad55cd03 | 350 | pam_retval = pam_set_item(pamh, PAM_TTY, "ssh"); |
cbd7492e | 351 | if (pam_retval != PAM_SUCCESS) { |
ebd782f7 | 352 | fatal("PAM set tty failed[%d]: %.200s", |
353 | pam_retval, PAM_STRERROR(pamh, pam_retval)); | |
cbd7492e | 354 | } |
a8545c6c | 355 | #endif /* PAM_TTY_KLUDGE */ |
cbd7492e | 356 | |
a5c9cd31 | 357 | fatal_add_cleanup(&pam_cleanup_proc, NULL); |
358 | } | |
359 | ||
360 | /* Return list of PAM enviornment strings */ | |
361 | char **fetch_pam_environment(void) | |
362 | { | |
2b763e31 | 363 | #ifdef HAVE_PAM_GETENVLIST |
ad55cd03 | 364 | return(pam_getenvlist(pamh)); |
2b763e31 | 365 | #else /* HAVE_PAM_GETENVLIST */ |
366 | return(NULL); | |
367 | #endif /* HAVE_PAM_GETENVLIST */ | |
a5c9cd31 | 368 | } |
369 | ||
370 | /* Print any messages that have been generated during authentication */ | |
371 | /* or account checking to stderr */ | |
372 | void print_pam_messages(void) | |
373 | { | |
5daf7064 | 374 | if (pam_msg != NULL) |
264dce47 | 375 | fputs(pam_msg, stderr); |
5daf7064 | 376 | } |
377 | ||
378 | /* Append a message to the PAM message buffer */ | |
379 | void pam_msg_cat(const char *msg) | |
380 | { | |
381 | char *p; | |
382 | size_t new_msg_len; | |
383 | size_t pam_msg_len; | |
384 | ||
385 | new_msg_len = strlen(msg); | |
386 | ||
387 | if (pam_msg) { | |
388 | pam_msg_len = strlen(pam_msg); | |
389 | pam_msg = xrealloc(pam_msg, new_msg_len + pam_msg_len + 2); | |
390 | p = pam_msg + pam_msg_len; | |
391 | } else { | |
392 | pam_msg = p = xmalloc(new_msg_len + 2); | |
393 | } | |
394 | ||
395 | memcpy(p, msg, new_msg_len); | |
396 | p[new_msg_len] = '\n'; | |
397 | p[new_msg_len + 1] = '\0'; | |
a5c9cd31 | 398 | } |
399 | ||
400 | #endif /* USE_PAM */ |