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1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ | |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <errno.h> | |
23 | #include <fcntl.h> | |
24 | #include <sys/file.h> | |
25 | #include <pwd.h> | |
26 | #include <endian.h> | |
27 | #include <sys/capability.h> | |
28 | ||
29 | #include <security/pam_modules.h> | |
30 | #include <security/_pam_macros.h> | |
31 | #include <security/pam_modutil.h> | |
32 | #include <security/pam_ext.h> | |
33 | #include <security/pam_misc.h> | |
34 | ||
35 | #include "util.h" | |
36 | #include "audit.h" | |
37 | #include "macro.h" | |
38 | #include "strv.h" | |
39 | #include "bus-util.h" | |
40 | #include "def.h" | |
41 | #include "socket-util.h" | |
42 | #include "fileio.h" | |
43 | #include "bus-error.h" | |
44 | ||
45 | static int parse_argv( | |
46 | pam_handle_t *handle, | |
47 | int argc, const char **argv, | |
48 | const char **class, | |
49 | const char **type, | |
50 | bool *debug) { | |
51 | ||
52 | unsigned i; | |
53 | ||
54 | assert(argc >= 0); | |
55 | assert(argc == 0 || argv); | |
56 | ||
57 | for (i = 0; i < (unsigned) argc; i++) { | |
58 | if (startswith(argv[i], "class=")) { | |
59 | if (class) | |
60 | *class = argv[i] + 6; | |
61 | ||
62 | } else if (startswith(argv[i], "type=")) { | |
63 | if (type) | |
64 | *type = argv[i] + 5; | |
65 | ||
66 | } else if (streq(argv[i], "debug")) { | |
67 | if (debug) | |
68 | *debug = true; | |
69 | ||
70 | } else if (startswith(argv[i], "debug=")) { | |
71 | int k; | |
72 | ||
73 | k = parse_boolean(argv[i] + 6); | |
74 | if (k < 0) | |
75 | pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring."); | |
76 | else if (debug) | |
77 | *debug = k; | |
78 | ||
79 | } else | |
80 | pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]); | |
81 | } | |
82 | ||
83 | return 0; | |
84 | } | |
85 | ||
86 | static int get_user_data( | |
87 | pam_handle_t *handle, | |
88 | const char **ret_username, | |
89 | struct passwd **ret_pw) { | |
90 | ||
91 | const char *username = NULL; | |
92 | struct passwd *pw = NULL; | |
93 | int r; | |
94 | ||
95 | assert(handle); | |
96 | assert(ret_username); | |
97 | assert(ret_pw); | |
98 | ||
99 | r = pam_get_user(handle, &username, NULL); | |
100 | if (r != PAM_SUCCESS) { | |
101 | pam_syslog(handle, LOG_ERR, "Failed to get user name."); | |
102 | return r; | |
103 | } | |
104 | ||
105 | if (isempty(username)) { | |
106 | pam_syslog(handle, LOG_ERR, "User name not valid."); | |
107 | return PAM_AUTH_ERR; | |
108 | } | |
109 | ||
110 | pw = pam_modutil_getpwnam(handle, username); | |
111 | if (!pw) { | |
112 | pam_syslog(handle, LOG_ERR, "Failed to get user data."); | |
113 | return PAM_USER_UNKNOWN; | |
114 | } | |
115 | ||
116 | *ret_pw = pw; | |
117 | *ret_username = username ? username : pw->pw_name; | |
118 | ||
119 | return PAM_SUCCESS; | |
120 | } | |
121 | ||
122 | static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) { | |
123 | union sockaddr_union sa = { | |
124 | .un.sun_family = AF_UNIX, | |
125 | }; | |
126 | _cleanup_free_ char *p = NULL, *tty = NULL; | |
127 | _cleanup_close_ int fd = -1; | |
128 | struct ucred ucred; | |
129 | int v, r; | |
130 | ||
131 | assert(display); | |
132 | assert(vtnr); | |
133 | ||
134 | /* We deduce the X11 socket from the display name, then use | |
135 | * SO_PEERCRED to determine the X11 server process, ask for | |
136 | * the controlling tty of that and if it's a VC then we know | |
137 | * the seat and the virtual terminal. Sounds ugly, is only | |
138 | * semi-ugly. */ | |
139 | ||
140 | r = socket_from_display(display, &p); | |
141 | if (r < 0) | |
142 | return r; | |
143 | strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1); | |
144 | ||
145 | fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0); | |
146 | if (fd < 0) | |
147 | return -errno; | |
148 | ||
149 | if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) | |
150 | return -errno; | |
151 | ||
152 | r = getpeercred(fd, &ucred); | |
153 | if (r < 0) | |
154 | return r; | |
155 | ||
156 | r = get_ctty(ucred.pid, NULL, &tty); | |
157 | if (r < 0) | |
158 | return r; | |
159 | ||
160 | v = vtnr_from_tty(tty); | |
161 | if (v < 0) | |
162 | return v; | |
163 | else if (v == 0) | |
164 | return -ENOENT; | |
165 | ||
166 | if (seat) | |
167 | *seat = "seat0"; | |
168 | *vtnr = (uint32_t) v; | |
169 | ||
170 | return 0; | |
171 | } | |
172 | ||
173 | static int export_legacy_dbus_address( | |
174 | pam_handle_t *handle, | |
175 | uid_t uid, | |
176 | const char *runtime) { | |
177 | ||
178 | #ifdef ENABLE_KDBUS | |
179 | _cleanup_free_ char *s = NULL; | |
180 | int r; | |
181 | ||
182 | /* skip export if kdbus is not active */ | |
183 | if (access("/dev/kdbus", F_OK) < 0) | |
184 | return PAM_SUCCESS; | |
185 | ||
186 | if (asprintf(&s, KERNEL_USER_BUS_FMT ";" UNIX_USER_BUS_FMT, | |
187 | (unsigned long) uid, runtime) < 0) { | |
188 | pam_syslog(handle, LOG_ERR, "Failed to set bus variable."); | |
189 | return PAM_BUF_ERR; | |
190 | } | |
191 | ||
192 | r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0); | |
193 | if (r != PAM_SUCCESS) { | |
194 | pam_syslog(handle, LOG_ERR, "Failed to set bus variable."); | |
195 | return r; | |
196 | } | |
197 | #endif | |
198 | return PAM_SUCCESS; | |
199 | } | |
200 | ||
201 | _public_ PAM_EXTERN int pam_sm_open_session( | |
202 | pam_handle_t *handle, | |
203 | int flags, | |
204 | int argc, const char **argv) { | |
205 | ||
206 | _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; | |
207 | _cleanup_bus_message_unref_ sd_bus_message *reply = NULL; | |
208 | const char | |
209 | *username, *id, *object_path, *runtime_path, | |
210 | *service = NULL, | |
211 | *tty = NULL, *display = NULL, | |
212 | *remote_user = NULL, *remote_host = NULL, | |
213 | *seat = NULL, | |
214 | *type = NULL, *class = NULL, | |
215 | *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL; | |
216 | _cleanup_bus_unref_ sd_bus *bus = NULL; | |
217 | int session_fd = -1, existing, r; | |
218 | bool debug = false, remote; | |
219 | struct passwd *pw; | |
220 | uint32_t vtnr = 0; | |
221 | uid_t original_uid; | |
222 | ||
223 | assert(handle); | |
224 | ||
225 | /* Make this a NOP on non-logind systems */ | |
226 | if (!logind_running()) | |
227 | return PAM_SUCCESS; | |
228 | ||
229 | if (parse_argv(handle, | |
230 | argc, argv, | |
231 | &class_pam, | |
232 | &type_pam, | |
233 | &debug) < 0) | |
234 | return PAM_SESSION_ERR; | |
235 | ||
236 | if (debug) | |
237 | pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing"); | |
238 | ||
239 | r = get_user_data(handle, &username, &pw); | |
240 | if (r != PAM_SUCCESS) { | |
241 | pam_syslog(handle, LOG_ERR, "Failed to get user data."); | |
242 | return r; | |
243 | } | |
244 | ||
245 | /* Make sure we don't enter a loop by talking to | |
246 | * systemd-logind when it is actually waiting for the | |
247 | * background to finish start-up. If the service is | |
248 | * "systemd-user" we simply set XDG_RUNTIME_DIR and | |
249 | * leave. */ | |
250 | ||
251 | pam_get_item(handle, PAM_SERVICE, (const void**) &service); | |
252 | if (streq_ptr(service, "systemd-user")) { | |
253 | _cleanup_free_ char *p = NULL, *rt = NULL; | |
254 | ||
255 | if (asprintf(&p, "/run/systemd/users/%lu", (unsigned long) pw->pw_uid) < 0) | |
256 | return PAM_BUF_ERR; | |
257 | ||
258 | r = parse_env_file(p, NEWLINE, | |
259 | "RUNTIME", &rt, | |
260 | NULL); | |
261 | if (r < 0 && r != -ENOENT) | |
262 | return PAM_SESSION_ERR; | |
263 | ||
264 | if (rt) { | |
265 | r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0); | |
266 | if (r != PAM_SUCCESS) { | |
267 | pam_syslog(handle, LOG_ERR, "Failed to set runtime dir."); | |
268 | return r; | |
269 | } | |
270 | ||
271 | r = export_legacy_dbus_address(handle, pw->pw_uid, rt); | |
272 | if (r != PAM_SUCCESS) | |
273 | return r; | |
274 | } | |
275 | ||
276 | return PAM_SUCCESS; | |
277 | } | |
278 | ||
279 | /* Otherwise, we ask logind to create a session for us */ | |
280 | ||
281 | pam_get_item(handle, PAM_XDISPLAY, (const void**) &display); | |
282 | pam_get_item(handle, PAM_TTY, (const void**) &tty); | |
283 | pam_get_item(handle, PAM_RUSER, (const void**) &remote_user); | |
284 | pam_get_item(handle, PAM_RHOST, (const void**) &remote_host); | |
285 | ||
286 | seat = pam_getenv(handle, "XDG_SEAT"); | |
287 | if (isempty(seat)) | |
288 | seat = getenv("XDG_SEAT"); | |
289 | ||
290 | cvtnr = pam_getenv(handle, "XDG_VTNR"); | |
291 | if (isempty(cvtnr)) | |
292 | cvtnr = getenv("XDG_VTNR"); | |
293 | ||
294 | type = pam_getenv(handle, "XDG_SESSION_TYPE"); | |
295 | if (isempty(type)) | |
296 | type = getenv("XDG_SESSION_TYPE"); | |
297 | if (isempty(type)) | |
298 | type = type_pam; | |
299 | ||
300 | class = pam_getenv(handle, "XDG_SESSION_CLASS"); | |
301 | if (isempty(class)) | |
302 | class = getenv("XDG_SESSION_CLASS"); | |
303 | if (isempty(class)) | |
304 | class = class_pam; | |
305 | ||
306 | desktop = pam_getenv(handle, "XDG_SESSION_DESKTOP"); | |
307 | if (isempty(desktop)) | |
308 | desktop = getenv("XDG_SESSION_DESKTOP"); | |
309 | ||
310 | tty = strempty(tty); | |
311 | ||
312 | if (strchr(tty, ':')) { | |
313 | /* A tty with a colon is usually an X11 display, | |
314 | * placed there to show up in utmp. We rearrange | |
315 | * things and don't pretend that an X display was a | |
316 | * tty. */ | |
317 | ||
318 | if (isempty(display)) | |
319 | display = tty; | |
320 | tty = NULL; | |
321 | } else if (streq(tty, "cron")) { | |
322 | /* cron has been setting PAM_TTY to "cron" for a very | |
323 | * long time and it probably shouldn't stop doing that | |
324 | * for compatibility reasons. */ | |
325 | type = "unspecified"; | |
326 | class = "background"; | |
327 | tty = NULL; | |
328 | } else if (streq(tty, "ssh")) { | |
329 | /* ssh has been setting PAM_TTY to "ssh" for a very | |
330 | * long time and probably shouldn't stop doing that | |
331 | * for compatibility reasons. */ | |
332 | type ="tty"; | |
333 | class = "user"; | |
334 | tty = NULL; | |
335 | } | |
336 | ||
337 | /* If this fails vtnr will be 0, that's intended */ | |
338 | if (!isempty(cvtnr)) | |
339 | safe_atou32(cvtnr, &vtnr); | |
340 | ||
341 | if (!isempty(display) && !vtnr) { | |
342 | if (isempty(seat)) | |
343 | get_seat_from_display(display, &seat, &vtnr); | |
344 | else if (streq(seat, "seat0")) | |
345 | get_seat_from_display(display, NULL, &vtnr); | |
346 | } | |
347 | ||
348 | if (seat && !streq(seat, "seat0") && vtnr != 0) { | |
349 | pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %d for %s which is not seat0", vtnr, seat); | |
350 | vtnr = 0; | |
351 | } | |
352 | ||
353 | if (isempty(type)) | |
354 | type = !isempty(display) ? "x11" : | |
355 | !isempty(tty) ? "tty" : "unspecified"; | |
356 | ||
357 | if (isempty(class)) | |
358 | class = streq(type, "unspecified") ? "background" : "user"; | |
359 | ||
360 | remote = !isempty(remote_host) && | |
361 | !streq_ptr(remote_host, "localhost") && | |
362 | !streq_ptr(remote_host, "localhost.localdomain"); | |
363 | ||
364 | /* Talk to logind over the message bus */ | |
365 | ||
366 | r = sd_bus_open_system(&bus); | |
367 | if (r < 0) { | |
368 | pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r)); | |
369 | return PAM_SESSION_ERR; | |
370 | } | |
371 | ||
372 | if (debug) | |
373 | pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: " | |
374 | "uid=%u pid=%u service=%s type=%s class=%s desktop=%s seat=%s vtnr=%u tty=%s display=%s remote=%s remote_user=%s remote_host=%s", | |
375 | pw->pw_uid, getpid(), | |
376 | strempty(service), | |
377 | type, class, strempty(desktop), | |
378 | strempty(seat), vtnr, strempty(tty), strempty(display), | |
379 | yes_no(remote), strempty(remote_user), strempty(remote_host)); | |
380 | ||
381 | r = sd_bus_call_method(bus, | |
382 | "org.freedesktop.login1", | |
383 | "/org/freedesktop/login1", | |
384 | "org.freedesktop.login1.Manager", | |
385 | "CreateSession", | |
386 | &error, | |
387 | &reply, | |
388 | "uusssssussbssa(sv)", | |
389 | (uint32_t) pw->pw_uid, | |
390 | (uint32_t) getpid(), | |
391 | service, | |
392 | type, | |
393 | class, | |
394 | desktop, | |
395 | seat, | |
396 | vtnr, | |
397 | tty, | |
398 | display, | |
399 | remote, | |
400 | remote_user, | |
401 | remote_host, | |
402 | 0); | |
403 | if (r < 0) { | |
404 | pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r)); | |
405 | return PAM_SYSTEM_ERR; | |
406 | } | |
407 | ||
408 | r = sd_bus_message_read(reply, | |
409 | "soshusub", | |
410 | &id, | |
411 | &object_path, | |
412 | &runtime_path, | |
413 | &session_fd, | |
414 | &original_uid, | |
415 | &seat, | |
416 | &vtnr, | |
417 | &existing); | |
418 | if (r < 0) { | |
419 | pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r)); | |
420 | return PAM_SESSION_ERR; | |
421 | } | |
422 | ||
423 | if (debug) | |
424 | pam_syslog(handle, LOG_DEBUG, "Reply from logind: " | |
425 | "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u", | |
426 | id, object_path, runtime_path, session_fd, seat, vtnr, original_uid); | |
427 | ||
428 | r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0); | |
429 | if (r != PAM_SUCCESS) { | |
430 | pam_syslog(handle, LOG_ERR, "Failed to set session id."); | |
431 | return r; | |
432 | } | |
433 | ||
434 | if (original_uid == pw->pw_uid) { | |
435 | /* Don't set $XDG_RUNTIME_DIR if the user we now | |
436 | * authenticated for does not match the original user | |
437 | * of the session. We do this in order not to result | |
438 | * in privileged apps clobbering the runtime directory | |
439 | * unnecessarily. */ | |
440 | ||
441 | r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0); | |
442 | if (r != PAM_SUCCESS) { | |
443 | pam_syslog(handle, LOG_ERR, "Failed to set runtime dir."); | |
444 | return r; | |
445 | } | |
446 | ||
447 | r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path); | |
448 | if (r != PAM_SUCCESS) | |
449 | return r; | |
450 | } | |
451 | ||
452 | if (!isempty(seat)) { | |
453 | r = pam_misc_setenv(handle, "XDG_SEAT", seat, 0); | |
454 | if (r != PAM_SUCCESS) { | |
455 | pam_syslog(handle, LOG_ERR, "Failed to set seat."); | |
456 | return r; | |
457 | } | |
458 | } | |
459 | ||
460 | if (vtnr > 0) { | |
461 | char buf[DECIMAL_STR_MAX(vtnr)]; | |
462 | sprintf(buf, "%u", vtnr); | |
463 | ||
464 | r = pam_misc_setenv(handle, "XDG_VTNR", buf, 0); | |
465 | if (r != PAM_SUCCESS) { | |
466 | pam_syslog(handle, LOG_ERR, "Failed to set virtual terminal number."); | |
467 | return r; | |
468 | } | |
469 | } | |
470 | ||
471 | r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL); | |
472 | if (r != PAM_SUCCESS) { | |
473 | pam_syslog(handle, LOG_ERR, "Failed to install existing flag."); | |
474 | return r; | |
475 | } | |
476 | ||
477 | if (session_fd >= 0) { | |
478 | session_fd = dup(session_fd); | |
479 | if (session_fd < 0) { | |
480 | pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m"); | |
481 | return PAM_SESSION_ERR; | |
482 | } | |
483 | ||
484 | r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL); | |
485 | if (r != PAM_SUCCESS) { | |
486 | pam_syslog(handle, LOG_ERR, "Failed to install session fd."); | |
487 | close_nointr_nofail(session_fd); | |
488 | return r; | |
489 | } | |
490 | } | |
491 | ||
492 | return PAM_SUCCESS; | |
493 | } | |
494 | ||
495 | _public_ PAM_EXTERN int pam_sm_close_session( | |
496 | pam_handle_t *handle, | |
497 | int flags, | |
498 | int argc, const char **argv) { | |
499 | ||
500 | _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; | |
501 | _cleanup_bus_unref_ sd_bus *bus = NULL; | |
502 | const void *existing = NULL; | |
503 | const char *id; | |
504 | int r; | |
505 | ||
506 | assert(handle); | |
507 | ||
508 | /* Only release session if it wasn't pre-existing when we | |
509 | * tried to create it */ | |
510 | pam_get_data(handle, "systemd.existing", &existing); | |
511 | ||
512 | id = pam_getenv(handle, "XDG_SESSION_ID"); | |
513 | if (id && !existing) { | |
514 | ||
515 | /* Before we go and close the FIFO we need to tell | |
516 | * logind that this is a clean session shutdown, so | |
517 | * that it doesn't just go and slaughter us | |
518 | * immediately after closing the fd */ | |
519 | ||
520 | r = sd_bus_open_system(&bus); | |
521 | if (r < 0) { | |
522 | pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r)); | |
523 | return PAM_SESSION_ERR; | |
524 | } | |
525 | ||
526 | r = sd_bus_call_method(bus, | |
527 | "org.freedesktop.login1", | |
528 | "/org/freedesktop/login1", | |
529 | "org.freedesktop.login1.Manager", | |
530 | "ReleaseSession", | |
531 | &error, | |
532 | NULL, | |
533 | "s", | |
534 | id); | |
535 | if (r < 0) { | |
536 | pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r)); | |
537 | return PAM_SESSION_ERR; | |
538 | } | |
539 | } | |
540 | ||
541 | /* Note that we are knowingly leaking the FIFO fd here. This | |
542 | * way, logind can watch us die. If we closed it here it would | |
543 | * not have any clue when that is completed. Given that one | |
544 | * cannot really have multiple PAM sessions open from the same | |
545 | * process this means we will leak one FD at max. */ | |
546 | ||
547 | return PAM_SUCCESS; | |
548 | } |