1 /* SPDX-License-Identifier: LGPL-2.1+ */
7 #include <security/_pam_macros.h>
8 #include <security/pam_ext.h>
9 #include <security/pam_misc.h>
10 #include <security/pam_modules.h>
11 #include <security/pam_modutil.h>
14 #include <sys/types.h>
17 #include "alloc-util.h"
18 #include "audit-util.h"
19 #include "bus-common-errors.h"
20 #include "bus-error.h"
21 #include "bus-internal.h"
23 #include "cgroup-setup.h"
24 #include "errno-util.h"
27 #include "format-util.h"
28 #include "hostname-util.h"
29 #include "login-util.h"
31 #include "parse-util.h"
32 #include "path-util.h"
33 #include "process-util.h"
34 #include "socket-util.h"
35 #include "stdio-util.h"
37 #include "terminal-util.h"
39 #define LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC (2*USEC_PER_MINUTE)
41 static int parse_argv(
43 int argc
, const char **argv
,
52 assert(argc
== 0 || argv
);
54 for (i
= 0; i
< (unsigned) argc
; i
++) {
57 if ((p
= startswith(argv
[i
], "class="))) {
61 } else if ((p
= startswith(argv
[i
], "type="))) {
65 } else if ((p
= startswith(argv
[i
], "desktop="))) {
69 } else if (streq(argv
[i
], "debug")) {
73 } else if ((p
= startswith(argv
[i
], "debug="))) {
78 pam_syslog(handle
, LOG_WARNING
, "Failed to parse debug= argument, ignoring: %s", p
);
83 pam_syslog(handle
, LOG_WARNING
, "Unknown parameter '%s', ignoring", argv
[i
]);
89 static int get_user_data(
91 const char **ret_username
,
92 struct passwd
**ret_pw
) {
94 const char *username
= NULL
;
95 struct passwd
*pw
= NULL
;
102 r
= pam_get_user(handle
, &username
, NULL
);
103 if (r
!= PAM_SUCCESS
) {
104 pam_syslog(handle
, LOG_ERR
, "Failed to get user name: %s", pam_strerror(handle
, r
));
108 if (isempty(username
)) {
109 pam_syslog(handle
, LOG_ERR
, "User name not valid.");
113 pw
= pam_modutil_getpwnam(handle
, username
);
115 pam_syslog(handle
, LOG_ERR
, "Failed to get user data.");
116 return PAM_USER_UNKNOWN
;
120 *ret_username
= username
;
125 static bool display_is_local(const char *display
) {
134 static int socket_from_display(const char *display
, char **path
) {
141 if (!display_is_local(display
))
144 k
= strspn(display
+1, "0123456789");
146 f
= new(char, STRLEN("/tmp/.X11-unix/X") + k
+ 1);
150 c
= stpcpy(f
, "/tmp/.X11-unix/X");
151 memcpy(c
, display
+1, k
);
159 static int get_seat_from_display(const char *display
, const char **seat
, uint32_t *vtnr
) {
160 union sockaddr_union sa
= {};
161 _cleanup_free_
char *p
= NULL
, *tty
= NULL
;
162 _cleanup_close_
int fd
= -1;
169 /* We deduce the X11 socket from the display name, then use
170 * SO_PEERCRED to determine the X11 server process, ask for
171 * the controlling tty of that and if it's a VC then we know
172 * the seat and the virtual terminal. Sounds ugly, is only
175 r
= socket_from_display(display
, &p
);
178 salen
= sockaddr_un_set_path(&sa
.un
, p
);
182 fd
= socket(AF_UNIX
, SOCK_STREAM
|SOCK_CLOEXEC
, 0);
186 if (connect(fd
, &sa
.sa
, salen
) < 0)
189 r
= getpeercred(fd
, &ucred
);
193 r
= get_ctty(ucred
.pid
, NULL
, &tty
);
197 v
= vtnr_from_tty(tty
);
205 *vtnr
= (uint32_t) v
;
210 static int export_legacy_dbus_address(
211 pam_handle_t
*handle
,
213 const char *runtime
) {
216 _cleanup_free_
char *t
= NULL
;
219 /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
220 * correctly to the bus without it. This setting matches what dbus.socket does for the user
221 * session using 'systemctl --user set-environment'. We want to have the same configuration
222 * in processes started from the PAM session.
224 * The setting of the address is guarded by the access() check because it is also possible to compile
225 * dbus without --enable-user-session, in which case this socket is not used, and
226 * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
227 * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
228 * expect the socket to be present by the time we do this check, so we can just as well check once
231 s
= strjoina(runtime
, "/bus");
232 if (access(s
, F_OK
) < 0)
235 if (asprintf(&t
, DEFAULT_USER_BUS_ADDRESS_FMT
, runtime
) < 0)
238 r
= pam_misc_setenv(handle
, "DBUS_SESSION_BUS_ADDRESS", t
, 0);
239 if (r
!= PAM_SUCCESS
)
245 pam_syslog(handle
, LOG_ERR
, "Failed to set bus variable.");
249 static int append_session_memory_max(pam_handle_t
*handle
, sd_bus_message
*m
, const char *limit
) {
256 if (streq(limit
, "infinity")) {
257 r
= sd_bus_message_append(m
, "(sv)", "MemoryMax", "t", (uint64_t)-1);
259 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
263 r
= parse_permille(limit
);
265 r
= sd_bus_message_append(m
, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r
* UINT32_MAX
) / 1000U));
267 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
271 r
= parse_size(limit
, 1024, &val
);
273 r
= sd_bus_message_append(m
, "(sv)", "MemoryMax", "t", val
);
275 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
279 pam_syslog(handle
, LOG_WARNING
, "Failed to parse systemd.memory_max: %s, ignoring.", limit
);
286 static int append_session_runtime_max_sec(pam_handle_t
*handle
, sd_bus_message
*m
, const char *limit
) {
290 /* No need to parse "infinity" here, it will be set by default later in scope_init() */
291 if (isempty(limit
) || streq(limit
, "infinity"))
294 r
= parse_sec(limit
, &val
);
296 r
= sd_bus_message_append(m
, "(sv)", "RuntimeMaxUSec", "t", (uint64_t) val
);
298 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
302 pam_syslog(handle
, LOG_WARNING
, "Failed to parse systemd.runtime_max_sec: %s, ignoring.", limit
);
307 static int append_session_tasks_max(pam_handle_t
*handle
, sd_bus_message
*m
, const char *limit
) {
311 /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
312 if (isempty(limit
) || streq(limit
, "infinity"))
315 r
= safe_atou64(limit
, &val
);
317 r
= sd_bus_message_append(m
, "(sv)", "TasksMax", "t", val
);
319 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
323 pam_syslog(handle
, LOG_WARNING
, "Failed to parse systemd.tasks_max: %s, ignoring.", limit
);
328 static int append_session_cg_weight(pam_handle_t
*handle
, sd_bus_message
*m
, const char *limit
, const char *field
) {
335 r
= cg_weight_parse(limit
, &val
);
337 r
= sd_bus_message_append(m
, "(sv)", field
, "t", val
);
339 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
342 } else if (streq(field
, "CPUWeight"))
343 pam_syslog(handle
, LOG_WARNING
, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit
);
345 pam_syslog(handle
, LOG_WARNING
, "Failed to parse systemd.io_weight: %s, ignoring.", limit
);
350 static const char* getenv_harder(pam_handle_t
*handle
, const char *key
, const char *fallback
) {
356 /* Looks for an environment variable, preferably in the environment block associated with the
357 * specified PAM handle, falling back to the process' block instead. Why check both? Because we want
358 * to permit configuration of session properties from unit files that invoke PAM services, so that
359 * PAM services don't have to be reworked to set systemd-specific properties, but these properties
360 * can still be set from the unit file Environment= block. */
362 v
= pam_getenv(handle
, key
);
366 /* We use secure_getenv() here, since we might get loaded into su/sudo, which are SUID. Ideally
367 * they'd clean up the environment before invoking foreign code (such as PAM modules), but alas they
368 * currently don't (to be precise, they clean up the environment they pass to their children, but
369 * not their own environ[]). */
370 v
= secure_getenv(key
);
377 static int update_environment(pam_handle_t
*handle
, const char *key
, const char *value
) {
383 /* Updates the environment, but only if there's actually a value set. Also, log about errors */
388 r
= pam_misc_setenv(handle
, key
, value
, 0);
389 if (r
!= PAM_SUCCESS
)
390 pam_syslog(handle
, LOG_ERR
, "Failed to set environment variable %s: %s", key
, pam_strerror(handle
, r
));
395 static bool validate_runtime_directory(pam_handle_t
*handle
, const char *path
, uid_t uid
) {
401 /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
402 * up properly for us. */
404 if (lstat(path
, &st
) < 0) {
405 pam_syslog(handle
, LOG_ERR
, "Failed to stat() runtime directory '%s': %s", path
, strerror_safe(errno
));
409 if (!S_ISDIR(st
.st_mode
)) {
410 pam_syslog(handle
, LOG_ERR
, "Runtime directory '%s' is not actually a directory.", path
);
414 if (st
.st_uid
!= uid
) {
415 pam_syslog(handle
, LOG_ERR
, "Runtime directory '%s' is not owned by UID " UID_FMT
", as it should.", path
, uid
);
422 pam_syslog(handle
, LOG_WARNING
, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
426 _public_ PAM_EXTERN
int pam_sm_open_session(
427 pam_handle_t
*handle
,
429 int argc
, const char **argv
) {
431 _cleanup_(sd_bus_error_free
) sd_bus_error error
= SD_BUS_ERROR_NULL
;
432 _cleanup_(sd_bus_message_unrefp
) sd_bus_message
*m
= NULL
, *reply
= NULL
;
434 *username
, *id
, *object_path
, *runtime_path
,
436 *tty
= NULL
, *display
= NULL
,
437 *remote_user
= NULL
, *remote_host
= NULL
,
439 *type
= NULL
, *class = NULL
,
440 *class_pam
= NULL
, *type_pam
= NULL
, *cvtnr
= NULL
, *desktop
= NULL
, *desktop_pam
= NULL
,
441 *memory_max
= NULL
, *tasks_max
= NULL
, *cpu_weight
= NULL
, *io_weight
= NULL
, *runtime_max_sec
= NULL
;
442 _cleanup_(sd_bus_flush_close_unrefp
) sd_bus
*bus
= NULL
;
443 int session_fd
= -1, existing
, r
;
444 bool debug
= false, remote
;
451 /* Make this a NOP on non-logind systems */
452 if (!logind_running())
455 if (parse_argv(handle
,
461 return PAM_SESSION_ERR
;
464 pam_syslog(handle
, LOG_DEBUG
, "pam-systemd initializing");
466 r
= get_user_data(handle
, &username
, &pw
);
467 if (r
!= PAM_SUCCESS
)
470 /* Make sure we don't enter a loop by talking to
471 * systemd-logind when it is actually waiting for the
472 * background to finish start-up. If the service is
473 * "systemd-user" we simply set XDG_RUNTIME_DIR and
476 (void) pam_get_item(handle
, PAM_SERVICE
, (const void**) &service
);
477 if (streq_ptr(service
, "systemd-user")) {
478 char rt
[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t
)];
480 xsprintf(rt
, "/run/user/"UID_FMT
, pw
->pw_uid
);
481 if (validate_runtime_directory(handle
, rt
, pw
->pw_uid
)) {
482 r
= pam_misc_setenv(handle
, "XDG_RUNTIME_DIR", rt
, 0);
483 if (r
!= PAM_SUCCESS
) {
484 pam_syslog(handle
, LOG_ERR
, "Failed to set runtime dir: %s", pam_strerror(handle
, r
));
489 r
= export_legacy_dbus_address(handle
, pw
->pw_uid
, rt
);
490 if (r
!= PAM_SUCCESS
)
496 /* Otherwise, we ask logind to create a session for us */
498 (void) pam_get_item(handle
, PAM_XDISPLAY
, (const void**) &display
);
499 (void) pam_get_item(handle
, PAM_TTY
, (const void**) &tty
);
500 (void) pam_get_item(handle
, PAM_RUSER
, (const void**) &remote_user
);
501 (void) pam_get_item(handle
, PAM_RHOST
, (const void**) &remote_host
);
503 seat
= getenv_harder(handle
, "XDG_SEAT", NULL
);
504 cvtnr
= getenv_harder(handle
, "XDG_VTNR", NULL
);
505 type
= getenv_harder(handle
, "XDG_SESSION_TYPE", type_pam
);
506 class = getenv_harder(handle
, "XDG_SESSION_CLASS", class_pam
);
507 desktop
= getenv_harder(handle
, "XDG_SESSION_DESKTOP", desktop_pam
);
511 if (strchr(tty
, ':')) {
512 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
513 * and don't pretend that an X display was a tty. */
514 if (isempty(display
))
518 } else if (streq(tty
, "cron")) {
519 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
520 * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
521 * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
523 type
= "unspecified";
524 class = "background";
527 } else if (streq(tty
, "ssh")) {
528 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
529 * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
532 tty
= NULL
; /* This one is particularly sad, as this means that ssh sessions — even though usually
533 * associated with a pty — won't be tracked by their tty in logind. This is because ssh
534 * does the PAM session registration early for new connections, and registers a pty only
535 * much later (this is because it doesn't know yet if it needs one at all, as whether to
536 * register a pty or not is negotiated much later in the protocol). */
539 /* Chop off leading /dev prefix that some clients specify, but others do not. */
540 tty
= skip_dev_prefix(tty
);
542 /* If this fails vtnr will be 0, that's intended */
544 (void) safe_atou32(cvtnr
, &vtnr
);
546 if (!isempty(display
) && !vtnr
) {
548 (void) get_seat_from_display(display
, &seat
, &vtnr
);
549 else if (streq(seat
, "seat0"))
550 (void) get_seat_from_display(display
, NULL
, &vtnr
);
553 if (seat
&& !streq(seat
, "seat0") && vtnr
!= 0) {
555 pam_syslog(handle
, LOG_DEBUG
, "Ignoring vtnr %"PRIu32
" for %s which is not seat0", vtnr
, seat
);
560 type
= !isempty(display
) ? "x11" :
561 !isempty(tty
) ? "tty" : "unspecified";
564 class = streq(type
, "unspecified") ? "background" : "user";
566 remote
= !isempty(remote_host
) && !is_localhost(remote_host
);
568 (void) pam_get_data(handle
, "systemd.memory_max", (const void **)&memory_max
);
569 (void) pam_get_data(handle
, "systemd.tasks_max", (const void **)&tasks_max
);
570 (void) pam_get_data(handle
, "systemd.cpu_weight", (const void **)&cpu_weight
);
571 (void) pam_get_data(handle
, "systemd.io_weight", (const void **)&io_weight
);
572 (void) pam_get_data(handle
, "systemd.runtime_max_sec", (const void **)&runtime_max_sec
);
574 /* Talk to logind over the message bus */
576 r
= sd_bus_open_system(&bus
);
578 pam_syslog(handle
, LOG_ERR
, "Failed to connect to system bus: %s", strerror_safe(r
));
579 return PAM_SESSION_ERR
;
583 pam_syslog(handle
, LOG_DEBUG
, "Asking logind to create session: "
584 "uid="UID_FMT
" pid="PID_FMT
" service=%s type=%s class=%s desktop=%s seat=%s vtnr=%"PRIu32
" tty=%s display=%s remote=%s remote_user=%s remote_host=%s",
585 pw
->pw_uid
, getpid_cached(),
587 type
, class, strempty(desktop
),
588 strempty(seat
), vtnr
, strempty(tty
), strempty(display
),
589 yes_no(remote
), strempty(remote_user
), strempty(remote_host
));
590 pam_syslog(handle
, LOG_DEBUG
, "Session limits: "
591 "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s runtime_max_sec=%s",
592 strna(memory_max
), strna(tasks_max
), strna(cpu_weight
), strna(io_weight
), strna(runtime_max_sec
));
595 r
= sd_bus_message_new_method_call(
598 "org.freedesktop.login1",
599 "/org/freedesktop/login1",
600 "org.freedesktop.login1.Manager",
603 pam_syslog(handle
, LOG_ERR
, "Failed to create CreateSession method call: %s", strerror_safe(r
));
604 return PAM_SESSION_ERR
;
607 r
= sd_bus_message_append(m
, "uusssssussbss",
608 (uint32_t) pw
->pw_uid
,
622 pam_syslog(handle
, LOG_ERR
, "Failed to append to bus message: %s", strerror_safe(r
));
623 return PAM_SESSION_ERR
;
626 r
= sd_bus_message_open_container(m
, 'a', "(sv)");
628 pam_syslog(handle
, LOG_ERR
, "Failed to open message container: %s", strerror_safe(r
));
629 return PAM_SYSTEM_ERR
;
632 r
= append_session_memory_max(handle
, m
, memory_max
);
634 return PAM_SESSION_ERR
;
636 r
= append_session_runtime_max_sec(handle
, m
, runtime_max_sec
);
638 return PAM_SESSION_ERR
;
640 r
= append_session_tasks_max(handle
, m
, tasks_max
);
642 return PAM_SESSION_ERR
;
644 r
= append_session_cg_weight(handle
, m
, cpu_weight
, "CPUWeight");
646 return PAM_SESSION_ERR
;
648 r
= append_session_cg_weight(handle
, m
, io_weight
, "IOWeight");
650 return PAM_SESSION_ERR
;
652 r
= sd_bus_message_close_container(m
);
654 pam_syslog(handle
, LOG_ERR
, "Failed to close message container: %s", strerror_safe(r
));
655 return PAM_SYSTEM_ERR
;
658 r
= sd_bus_call(bus
, m
, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC
, &error
, &reply
);
660 if (sd_bus_error_has_name(&error
, BUS_ERROR_SESSION_BUSY
)) {
662 pam_syslog(handle
, LOG_DEBUG
, "Not creating session: %s", bus_error_message(&error
, r
));
665 pam_syslog(handle
, LOG_ERR
, "Failed to create session: %s", bus_error_message(&error
, r
));
666 return PAM_SESSION_ERR
;
670 r
= sd_bus_message_read(reply
,
681 pam_syslog(handle
, LOG_ERR
, "Failed to parse message: %s", strerror_safe(r
));
682 return PAM_SESSION_ERR
;
686 pam_syslog(handle
, LOG_DEBUG
, "Reply from logind: "
687 "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
688 id
, object_path
, runtime_path
, session_fd
, seat
, vtnr
, original_uid
);
690 r
= update_environment(handle
, "XDG_SESSION_ID", id
);
691 if (r
!= PAM_SUCCESS
)
694 if (original_uid
== pw
->pw_uid
) {
695 /* Don't set $XDG_RUNTIME_DIR if the user we now
696 * authenticated for does not match the original user
697 * of the session. We do this in order not to result
698 * in privileged apps clobbering the runtime directory
701 if (validate_runtime_directory(handle
, runtime_path
, pw
->pw_uid
)) {
702 r
= update_environment(handle
, "XDG_RUNTIME_DIR", runtime_path
);
703 if (r
!= PAM_SUCCESS
)
707 r
= export_legacy_dbus_address(handle
, pw
->pw_uid
, runtime_path
);
708 if (r
!= PAM_SUCCESS
)
712 /* Most likely we got the session/type/class from environment variables, but might have gotten the data
713 * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
714 * data is inherited into the session processes, and programs can rely on them to be initialized. */
716 r
= update_environment(handle
, "XDG_SESSION_TYPE", type
);
717 if (r
!= PAM_SUCCESS
)
720 r
= update_environment(handle
, "XDG_SESSION_CLASS", class);
721 if (r
!= PAM_SUCCESS
)
724 r
= update_environment(handle
, "XDG_SESSION_DESKTOP", desktop
);
725 if (r
!= PAM_SUCCESS
)
728 r
= update_environment(handle
, "XDG_SEAT", seat
);
729 if (r
!= PAM_SUCCESS
)
733 char buf
[DECIMAL_STR_MAX(vtnr
)];
734 sprintf(buf
, "%u", vtnr
);
736 r
= update_environment(handle
, "XDG_VTNR", buf
);
737 if (r
!= PAM_SUCCESS
)
741 r
= pam_set_data(handle
, "systemd.existing", INT_TO_PTR(!!existing
), NULL
);
742 if (r
!= PAM_SUCCESS
) {
743 pam_syslog(handle
, LOG_ERR
, "Failed to install existing flag: %s", pam_strerror(handle
, r
));
747 if (session_fd
>= 0) {
748 session_fd
= fcntl(session_fd
, F_DUPFD_CLOEXEC
, 3);
749 if (session_fd
< 0) {
750 pam_syslog(handle
, LOG_ERR
, "Failed to dup session fd: %m");
751 return PAM_SESSION_ERR
;
754 r
= pam_set_data(handle
, "systemd.session-fd", FD_TO_PTR(session_fd
), NULL
);
755 if (r
!= PAM_SUCCESS
) {
756 pam_syslog(handle
, LOG_ERR
, "Failed to install session fd: %s", pam_strerror(handle
, r
));
757 safe_close(session_fd
);
765 _public_ PAM_EXTERN
int pam_sm_close_session(
766 pam_handle_t
*handle
,
768 int argc
, const char **argv
) {
770 _cleanup_(sd_bus_error_free
) sd_bus_error error
= SD_BUS_ERROR_NULL
;
771 _cleanup_(sd_bus_flush_close_unrefp
) sd_bus
*bus
= NULL
;
772 const void *existing
= NULL
;
778 /* Only release session if it wasn't pre-existing when we
779 * tried to create it */
780 (void) pam_get_data(handle
, "systemd.existing", &existing
);
782 id
= pam_getenv(handle
, "XDG_SESSION_ID");
783 if (id
&& !existing
) {
785 /* Before we go and close the FIFO we need to tell
786 * logind that this is a clean session shutdown, so
787 * that it doesn't just go and slaughter us
788 * immediately after closing the fd */
790 r
= sd_bus_open_system(&bus
);
792 pam_syslog(handle
, LOG_ERR
, "Failed to connect to system bus: %s", strerror_safe(r
));
793 return PAM_SESSION_ERR
;
796 r
= sd_bus_call_method(bus
,
797 "org.freedesktop.login1",
798 "/org/freedesktop/login1",
799 "org.freedesktop.login1.Manager",
806 pam_syslog(handle
, LOG_ERR
, "Failed to release session: %s", bus_error_message(&error
, r
));
807 return PAM_SESSION_ERR
;
811 /* Note that we are knowingly leaking the FIFO fd here. This
812 * way, logind can watch us die. If we closed it here it would
813 * not have any clue when that is completed. Given that one
814 * cannot really have multiple PAM sessions open from the same
815 * process this means we will leak one FD at max. */