pam_systemd.c revision f9e4283df30ad8916878396da449b2e38656b6f7
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <security/_pam_macros.h>
#include <security/pam_ext.h>
#include <security/pam_misc.h>
#include <security/pam_modules.h>
#include <security/pam_modutil.h>
#include <sys/file.h>
#include "alloc-util.h"
#include "audit-util.h"
#include "bus-common-errors.h"
#include "bus-error.h"
#include "bus-util.h"
#include "def.h"
#include "fd-util.h"
#include "fileio.h"
#include "formats-util.h"
#include "hostname-util.h"
#include "login-util.h"
#include "macro.h"
#include "parse-util.h"
#include "socket-util.h"
#include "strv.h"
#include "terminal-util.h"
#include "util.h"
static int parse_argv(
pam_handle_t *handle,
int argc, const char **argv,
const char **class,
const char **type,
bool *debug) {
unsigned i;
assert(argc >= 0);
assert(argc == 0 || argv);
for (i = 0; i < (unsigned) argc; i++) {
if (startswith(argv[i], "class=")) {
if (class)
*class = argv[i] + 6;
} else if (startswith(argv[i], "type=")) {
if (type)
*type = argv[i] + 5;
} else if (streq(argv[i], "debug")) {
if (debug)
*debug = true;
} else if (startswith(argv[i], "debug=")) {
int k;
k = parse_boolean(argv[i] + 6);
if (k < 0)
pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
else if (debug)
*debug = k;
} else
pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
}
return 0;
}
static int get_user_data(
pam_handle_t *handle,
const char **ret_username,
struct passwd **ret_pw) {
const char *username = NULL;
struct passwd *pw = NULL;
int r;
assert(handle);
assert(ret_username);
assert(ret_pw);
r = pam_get_user(handle, &username, NULL);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to get user name.");
return r;
}
if (isempty(username)) {
pam_syslog(handle, LOG_ERR, "User name not valid.");
return PAM_AUTH_ERR;
}
pw = pam_modutil_getpwnam(handle, username);
if (!pw) {
pam_syslog(handle, LOG_ERR, "Failed to get user data.");
return PAM_USER_UNKNOWN;
}
*ret_pw = pw;
*ret_username = username;
return PAM_SUCCESS;
}
static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
};
_cleanup_free_ char *p = NULL, *tty = NULL;
_cleanup_close_ int fd = -1;
struct ucred ucred;
int v, r;
assert(display);
assert(vtnr);
/* We deduce the X11 socket from the display name, then use
* SO_PEERCRED to determine the X11 server process, ask for
* the controlling tty of that and if it's a VC then we know
* the seat and the virtual terminal. Sounds ugly, is only
* semi-ugly. */
r = socket_from_display(display, &p);
if (r < 0)
return r;
strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1);
fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (fd < 0)
return -errno;
if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0)
return -errno;
r = getpeercred(fd, &ucred);
if (r < 0)
return r;
r = get_ctty(ucred.pid, NULL, &tty);
if (r < 0)
return r;
v = vtnr_from_tty(tty);
if (v < 0)
return v;
else if (v == 0)
return -ENOENT;
if (seat)
*seat = "seat0";
*vtnr = (uint32_t) v;
return 0;
}
static int export_legacy_dbus_address(
pam_handle_t *handle,
uid_t uid,
const char *runtime) {
_cleanup_free_ char *s = NULL;
int r = PAM_BUF_ERR;
if (is_kdbus_available()) {
if (asprintf(&s, KERNEL_USER_BUS_ADDRESS_FMT ";" UNIX_USER_BUS_ADDRESS_FMT, uid, runtime) < 0)
goto error;
} else {
/* FIXME: We *really* should move the access() check into the
* daemons that spawn dbus-daemon, instead of forcing
* DBUS_SESSION_BUS_ADDRESS= here. */
s = strjoin(runtime, "/bus", NULL);
if (!s)
goto error;
if (access(s, F_OK) < 0)
return PAM_SUCCESS;
s = mfree(s);
if (asprintf(&s, UNIX_USER_BUS_ADDRESS_FMT, runtime) < 0)
goto error;
}
r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0);
if (r != PAM_SUCCESS)
goto error;
return PAM_SUCCESS;
error:
pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
return r;
}
_public_ PAM_EXTERN int pam_sm_open_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
const char
*username, *id, *object_path, *runtime_path,
*service = NULL,
*tty = NULL, *display = NULL,
*remote_user = NULL, *remote_host = NULL,
*seat = NULL,
*type = NULL, *class = NULL,
*class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL;
_cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
int session_fd = -1, existing, r;
bool debug = false, remote;
struct passwd *pw;
uint32_t vtnr = 0;
uid_t original_uid;
assert(handle);
/* Make this a NOP on non-logind systems */
if (!logind_running())
return PAM_SUCCESS;
if (parse_argv(handle,
argc, argv,
&class_pam,
&type_pam,
&debug) < 0)
return PAM_SESSION_ERR;
if (debug)
pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
r = get_user_data(handle, &username, &pw);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to get user data.");
return r;
}
/* Make sure we don't enter a loop by talking to
* systemd-logind when it is actually waiting for the
* background to finish start-up. If the service is
* "systemd-user" we simply set XDG_RUNTIME_DIR and
* leave. */
pam_get_item(handle, PAM_SERVICE, (const void**) &service);
if (streq_ptr(service, "systemd-user")) {
_cleanup_free_ char *rt = NULL;
if (asprintf(&rt, "/run/user/"UID_FMT, pw->pw_uid) < 0)
return PAM_BUF_ERR;
r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
return r;
}
r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
if (r != PAM_SUCCESS)
return r;
return PAM_SUCCESS;
}
/* Otherwise, we ask logind to create a session for us */
pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
pam_get_item(handle, PAM_TTY, (const void**) &tty);
pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
seat = pam_getenv(handle, "XDG_SEAT");
if (isempty(seat))
seat = getenv("XDG_SEAT");
cvtnr = pam_getenv(handle, "XDG_VTNR");
if (isempty(cvtnr))
cvtnr = getenv("XDG_VTNR");
type = pam_getenv(handle, "XDG_SESSION_TYPE");
if (isempty(type))
type = getenv("XDG_SESSION_TYPE");
if (isempty(type))
type = type_pam;
class = pam_getenv(handle, "XDG_SESSION_CLASS");
if (isempty(class))
class = getenv("XDG_SESSION_CLASS");
if (isempty(class))
class = class_pam;
desktop = pam_getenv(handle, "XDG_SESSION_DESKTOP");
if (isempty(desktop))
desktop = getenv("XDG_SESSION_DESKTOP");
tty = strempty(tty);
if (strchr(tty, ':')) {
/* A tty with a colon is usually an X11 display,
* placed there to show up in utmp. We rearrange
* things and don't pretend that an X display was a
* tty. */
if (isempty(display))
display = tty;
tty = NULL;
} else if (streq(tty, "cron")) {
/* cron has been setting PAM_TTY to "cron" for a very
* long time and it probably shouldn't stop doing that
* for compatibility reasons. */
type = "unspecified";
class = "background";
tty = NULL;
} else if (streq(tty, "ssh")) {
/* ssh has been setting PAM_TTY to "ssh" for a very
* long time and probably shouldn't stop doing that
* for compatibility reasons. */
type ="tty";
class = "user";
tty = NULL;
}
/* If this fails vtnr will be 0, that's intended */
if (!isempty(cvtnr))
(void) safe_atou32(cvtnr, &vtnr);
if (!isempty(display) && !vtnr) {
if (isempty(seat))
get_seat_from_display(display, &seat, &vtnr);
else if (streq(seat, "seat0"))
get_seat_from_display(display, NULL, &vtnr);
}
if (seat && !streq(seat, "seat0") && vtnr != 0) {
pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
vtnr = 0;
}
if (isempty(type))
type = !isempty(display) ? "x11" :
!isempty(tty) ? "tty" : "unspecified";
if (isempty(class))
class = streq(type, "unspecified") ? "background" : "user";
remote = !isempty(remote_host) && !is_localhost(remote_host);
/* Talk to logind over the message bus */
r = sd_bus_open_system(&bus);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
return PAM_SESSION_ERR;
}
if (debug)
pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
"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",
pw->pw_uid, getpid(),
strempty(service),
type, class, strempty(desktop),
strempty(seat), vtnr, strempty(tty), strempty(display),
yes_no(remote), strempty(remote_user), strempty(remote_host));
r = sd_bus_call_method(bus,
"org.freedesktop.login1",
"/org/freedesktop/login1",
"org.freedesktop.login1.Manager",
"CreateSession",
&error,
&reply,
"uusssssussbssa(sv)",
(uint32_t) pw->pw_uid,
(uint32_t) getpid(),
service,
type,
class,
desktop,
seat,
vtnr,
tty,
display,
remote,
remote_user,
remote_host,
0);
if (r < 0) {
if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
pam_syslog(handle, LOG_DEBUG, "Cannot create session: %s", bus_error_message(&error, r));
return PAM_SUCCESS;
} else {
pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
return PAM_SYSTEM_ERR;
}
}
r = sd_bus_message_read(reply,
"soshusub",
&id,
&object_path,
&runtime_path,
&session_fd,
&original_uid,
&seat,
&vtnr,
&existing);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r));
return PAM_SESSION_ERR;
}
if (debug)
pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
"id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set session id.");
return r;
}
if (original_uid == pw->pw_uid) {
/* Don't set $XDG_RUNTIME_DIR if the user we now
* authenticated for does not match the original user
* of the session. We do this in order not to result
* in privileged apps clobbering the runtime directory
* unnecessarily. */
r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
return r;
}
r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
if (r != PAM_SUCCESS)
return r;
}
if (!isempty(seat)) {
r = pam_misc_setenv(handle, "XDG_SEAT", seat, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set seat.");
return r;
}
}
if (vtnr > 0) {
char buf[DECIMAL_STR_MAX(vtnr)];
sprintf(buf, "%u", vtnr);
r = pam_misc_setenv(handle, "XDG_VTNR", buf, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set virtual terminal number.");
return r;
}
}
r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
return r;
}
if (session_fd >= 0) {
session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
if (session_fd < 0) {
pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
return PAM_SESSION_ERR;
}
r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
safe_close(session_fd);
return r;
}
}
return PAM_SUCCESS;
}
_public_ PAM_EXTERN int pam_sm_close_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
const void *existing = NULL;
const char *id;
int r;
assert(handle);
/* Only release session if it wasn't pre-existing when we
* tried to create it */
pam_get_data(handle, "systemd.existing", &existing);
id = pam_getenv(handle, "XDG_SESSION_ID");
if (id && !existing) {
/* Before we go and close the FIFO we need to tell
* logind that this is a clean session shutdown, so
* that it doesn't just go and slaughter us
* immediately after closing the fd */
r = sd_bus_open_system(&bus);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
return PAM_SESSION_ERR;
}
r = sd_bus_call_method(bus,
"org.freedesktop.login1",
"/org/freedesktop/login1",
"org.freedesktop.login1.Manager",
"ReleaseSession",
&error,
NULL,
"s",
id);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
return PAM_SESSION_ERR;
}
}
/* Note that we are knowingly leaking the FIFO fd here. This
* way, logind can watch us die. If we closed it here it would
* not have any clue when that is completed. Given that one
* cannot really have multiple PAM sessions open from the same
* process this means we will leak one FD at max. */
return PAM_SUCCESS;
}