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134144abc8
systemd/src/login/pam_systemd.c
Riccardo Schirone 148369deef Check return value of pam_get_item/pam_get_data functions
2021-07-27 11:59:46 +02:00

1070 lines
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#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 <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <unistd.h>
#include "alloc-util.h"
#include "audit-util.h"
#include "bus-common-errors.h"
#include "bus-error.h"
#include "bus-internal.h"
#include "bus-locator.h"
#include "cgroup-setup.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "fs-util.h"
#include "hostname-util.h"
#include "locale-util.h"
#include "login-util.h"
#include "macro.h"
#include "pam-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "percent-util.h"
#include "process-util.h"
#include "rlimit-util.h"
#include "socket-util.h"
#include "stdio-util.h"
#include "strv.h"
#include "terminal-util.h"
#include "user-util.h"
#include "userdb.h"
#define LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC (2*USEC_PER_MINUTE)
static int parse_argv(
pam_handle_t *handle,
int argc, const char **argv,
const char **class,
const char **type,
const char **desktop,
bool *debug) {
unsigned i;
assert(argc >= 0);
assert(argc == 0 || argv);
for (i = 0; i < (unsigned) argc; i++) {
const char *p;
if ((p = startswith(argv[i], "class="))) {
if (class)
*class = p;
} else if ((p = startswith(argv[i], "type="))) {
if (type)
*type = p;
} else if ((p = startswith(argv[i], "desktop="))) {
if (desktop)
*desktop = p;
} else if (streq(argv[i], "debug")) {
if (debug)
*debug = true;
} else if ((p = startswith(argv[i], "debug="))) {
int k;
k = parse_boolean(p);
if (k < 0)
pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring: %s", p);
else if (debug)
*debug = k;
} else
pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
}
return 0;
}
static int acquire_user_record(
pam_handle_t *handle,
UserRecord **ret_record) {
_cleanup_(user_record_unrefp) UserRecord *ur = NULL;
const char *username = NULL, *json = NULL;
_cleanup_free_ char *field = NULL;
int r;
assert(handle);
r = pam_get_user(handle, &username, NULL);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to get user name: %s", pam_strerror(handle, r));
return r;
}
if (isempty(username)) {
pam_syslog(handle, LOG_ERR, "User name not valid.");
return PAM_SERVICE_ERR;
}
/* If pam_systemd_homed (or some other module) already acquired the user record we can reuse it
* here. */
field = strjoin("systemd-user-record-", username);
if (!field)
return pam_log_oom(handle);
r = pam_get_data(handle, field, (const void**) &json);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM user record data: %s", pam_strerror(handle, r));
return r;
}
if (r == PAM_SUCCESS && json) {
_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
/* Parse cached record */
r = json_parse(json, JSON_PARSE_SENSITIVE, &v, NULL, NULL);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to parse JSON user record: %s", strerror_safe(r));
return PAM_SERVICE_ERR;
}
ur = user_record_new();
if (!ur)
return pam_log_oom(handle);
r = user_record_load(ur, v, USER_RECORD_LOAD_REFUSE_SECRET|USER_RECORD_PERMISSIVE);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to load user record: %s", strerror_safe(r));
return PAM_SERVICE_ERR;
}
/* Safety check if cached record actually matches what we are looking for */
if (!streq_ptr(username, ur->user_name)) {
pam_syslog(handle, LOG_ERR, "Acquired user record does not match user name.");
return PAM_SERVICE_ERR;
}
} else {
_cleanup_free_ char *formatted = NULL;
/* Request the record ourselves */
r = userdb_by_name(username, 0, &ur);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to get user record: %s", strerror_safe(r));
return PAM_USER_UNKNOWN;
}
r = json_variant_format(ur->json, 0, &formatted);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to format user JSON: %s", strerror_safe(r));
return PAM_SERVICE_ERR;
}
/* And cache it for everyone else */
r = pam_set_data(handle, field, formatted, pam_cleanup_free);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to set PAM user record data '%s': %s",
field, pam_strerror(handle, r));
return r;
}
TAKE_PTR(formatted);
}
if (!uid_is_valid(ur->uid)) {
pam_syslog(handle, LOG_ERR, "Acquired user record does not have a UID.");
return PAM_SERVICE_ERR;
}
if (ret_record)
*ret_record = TAKE_PTR(ur);
return PAM_SUCCESS;
}
static bool display_is_local(const char *display) {
assert(display);
return
display[0] == ':' &&
display[1] >= '0' &&
display[1] <= '9';
}
static int socket_from_display(const char *display, char **path) {
size_t k;
char *f, *c;
assert(display);
assert(path);
if (!display_is_local(display))
return -EINVAL;
k = strspn(display+1, "0123456789");
f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
if (!f)
return -ENOMEM;
c = stpcpy(f, "/tmp/.X11-unix/X");
memcpy(c, display+1, k);
c[k] = 0;
*path = f;
return 0;
}
static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
union sockaddr_union sa;
socklen_t sa_len;
_cleanup_free_ char *p = NULL, *sys_path = NULL, *tty = NULL;
_cleanup_close_ int fd = -1;
struct ucred ucred;
int v, r;
dev_t display_ctty;
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;
r = sockaddr_un_set_path(&sa.un, p);
if (r < 0)
return r;
sa_len = r;
fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (fd < 0)
return -errno;
if (connect(fd, &sa.sa, sa_len) < 0)
return -errno;
r = getpeercred(fd, &ucred);
if (r < 0)
return r;
r = get_ctty_devnr(ucred.pid, &display_ctty);
if (r < 0)
return r;
if (asprintf(&sys_path, "/sys/dev/char/%d:%d", major(display_ctty), minor(display_ctty)) < 0)
return -ENOMEM;
r = readlink_value(sys_path, &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,
const char *runtime) {
const char *s;
_cleanup_free_ char *t = NULL;
int r = PAM_BUF_ERR;
/* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
* correctly to the bus without it. This setting matches what dbus.socket does for the user
* session using 'systemctl --user set-environment'. We want to have the same configuration
* in processes started from the PAM session.
*
* The setting of the address is guarded by the access() check because it is also possible to compile
* dbus without --enable-user-session, in which case this socket is not used, and
* $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
* check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
* expect the socket to be present by the time we do this check, so we can just as well check once
* here. */
s = strjoina(runtime, "/bus");
if (access(s, F_OK) < 0)
return PAM_SUCCESS;
if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
return pam_log_oom(handle);
r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set bus variable: %s", pam_strerror(handle, r));
return r;
}
return PAM_SUCCESS;
}
static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
uint64_t val;
int r;
if (isempty(limit))
return PAM_SUCCESS;
if (streq(limit, "infinity")) {
r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", UINT64_MAX);
if (r < 0)
return pam_bus_log_create_error(handle, r);
return PAM_SUCCESS;
}
r = parse_permyriad(limit);
if (r >= 0) {
r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", UINT32_SCALE_FROM_PERMYRIAD(r));
if (r < 0)
return pam_bus_log_create_error(handle, r);
return PAM_SUCCESS;
}
r = parse_size(limit, 1024, &val);
if (r >= 0) {
r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
if (r < 0)
return pam_bus_log_create_error(handle, r);
return PAM_SUCCESS;
}
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max, ignoring: %s", limit);
return PAM_SUCCESS;
}
static int append_session_runtime_max_sec(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
usec_t val;
int r;
/* No need to parse "infinity" here, it will be set by default later in scope_init() */
if (isempty(limit) || streq(limit, "infinity"))
return PAM_SUCCESS;
r = parse_sec(limit, &val);
if (r >= 0) {
r = sd_bus_message_append(m, "(sv)", "RuntimeMaxUSec", "t", (uint64_t) val);
if (r < 0)
return pam_bus_log_create_error(handle, r);
} else
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.runtime_max_sec: %s, ignoring.", limit);
return PAM_SUCCESS;
}
static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
uint64_t val;
int r;
/* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
if (isempty(limit) || streq(limit, "infinity"))
return PAM_SUCCESS;
r = safe_atou64(limit, &val);
if (r >= 0) {
r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
if (r < 0)
return pam_bus_log_create_error(handle, r);
} else
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max, ignoring: %s", limit);
return PAM_SUCCESS;
}
static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
uint64_t val;
int r;
if (isempty(limit))
return PAM_SUCCESS;
r = cg_weight_parse(limit, &val);
if (r >= 0) {
r = sd_bus_message_append(m, "(sv)", field, "t", val);
if (r < 0)
return pam_bus_log_create_error(handle, r);
} else if (streq(field, "CPUWeight"))
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight, ignoring: %s", limit);
else
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight, ignoring: %s", limit);
return PAM_SUCCESS;
}
static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
const char *v;
assert(handle);
assert(key);
/* Looks for an environment variable, preferably in the environment block associated with the
* specified PAM handle, falling back to the process' block instead. Why check both? Because we want
* to permit configuration of session properties from unit files that invoke PAM services, so that
* PAM services don't have to be reworked to set systemd-specific properties, but these properties
* can still be set from the unit file Environment= block. */
v = pam_getenv(handle, key);
if (!isempty(v))
return v;
/* We use secure_getenv() here, since we might get loaded into su/sudo, which are SUID. Ideally
* they'd clean up the environment before invoking foreign code (such as PAM modules), but alas they
* currently don't (to be precise, they clean up the environment they pass to their children, but
* not their own environ[]). */
v = secure_getenv(key);
if (!isempty(v))
return v;
return fallback;
}
static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
int r;
assert(handle);
assert(key);
/* Updates the environment, but only if there's actually a value set. Also, log about errors */
if (isempty(value))
return PAM_SUCCESS;
r = pam_misc_setenv(handle, key, value, 0);
if (r != PAM_SUCCESS)
pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s: %s", key, pam_strerror(handle, r));
return r;
}
static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
struct stat st;
assert(handle);
assert(path);
/* Some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually
* set up properly for us. This is supposed to provide a careful safety net for supporting su/sudo
* type transitions: in that case the UID changes, but the session and thus the user owning it
* doesn't change. Since the $XDG_RUNTIME_DIR lifecycle is bound to the session's user being logged
* in at least once we should be particularly careful when setting the environment variable, since
* otherwise we might end up setting $XDG_RUNTIME_DIR to some directory owned by the wrong user. */
if (!path_is_absolute(path)) {
pam_syslog(handle, LOG_ERR, "Provided runtime directory '%s' is not absolute.", path);
goto fail;
}
if (lstat(path, &st) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror_safe(errno));
goto fail;
}
if (!S_ISDIR(st.st_mode)) {
pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
goto fail;
}
if (st.st_uid != uid) {
pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
goto fail;
}
return true;
fail:
pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
return false;
}
static int pam_putenv_and_log(pam_handle_t *handle, const char *e, bool debug) {
int r;
assert(handle);
assert(e);
r = pam_putenv(handle, e);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set PAM environment variable %s: %s", e, pam_strerror(handle, r));
return r;
}
if (debug)
pam_syslog(handle, LOG_DEBUG, "PAM environment variable %s set based on user record.", e);
return PAM_SUCCESS;
}
static int apply_user_record_settings(pam_handle_t *handle, UserRecord *ur, bool debug) {
char **i;
int r;
assert(handle);
assert(ur);
if (ur->umask != MODE_INVALID) {
umask(ur->umask);
if (debug)
pam_syslog(handle, LOG_DEBUG, "Set user umask to %04o based on user record.", ur->umask);
}
STRV_FOREACH(i, ur->environment) {
_cleanup_free_ char *n = NULL;
const char *e;
assert_se(e = strchr(*i, '=')); /* environment was already validated while parsing JSON record, this thus must hold */
n = strndup(*i, e - *i);
if (!n)
return pam_log_oom(handle);
if (pam_getenv(handle, n)) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "PAM environment variable $%s already set, not changing based on record.", *i);
continue;
}
r = pam_putenv_and_log(handle, *i, debug);
if (r != PAM_SUCCESS)
return r;
}
if (ur->email_address) {
if (pam_getenv(handle, "EMAIL")) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "PAM environment variable $EMAIL already set, not changing based on user record.");
} else {
_cleanup_free_ char *joined = NULL;
joined = strjoin("EMAIL=", ur->email_address);
if (!joined)
return pam_log_oom(handle);
r = pam_putenv_and_log(handle, joined, debug);
if (r != PAM_SUCCESS)
return r;
}
}
if (ur->time_zone) {
if (pam_getenv(handle, "TZ")) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "PAM environment variable $TZ already set, not changing based on user record.");
} else if (!timezone_is_valid(ur->time_zone, LOG_DEBUG)) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "Time zone specified in user record is not valid locally, not setting $TZ.");
} else {
_cleanup_free_ char *joined = NULL;
joined = strjoin("TZ=:", ur->time_zone);
if (!joined)
return pam_log_oom(handle);
r = pam_putenv_and_log(handle, joined, debug);
if (r != PAM_SUCCESS)
return r;
}
}
if (ur->preferred_language) {
if (pam_getenv(handle, "LANG")) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "PAM environment variable $LANG already set, not changing based on user record.");
} else if (locale_is_installed(ur->preferred_language) <= 0) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "Preferred language specified in user record is not valid or not installed, not setting $LANG.");
} else {
_cleanup_free_ char *joined = NULL;
joined = strjoin("LANG=", ur->preferred_language);
if (!joined)
return pam_log_oom(handle);
r = pam_putenv_and_log(handle, joined, debug);
if (r != PAM_SUCCESS)
return r;
}
}
if (nice_is_valid(ur->nice_level)) {
if (nice(ur->nice_level) < 0)
pam_syslog(handle, LOG_ERR, "Failed to set nice level to %i, ignoring: %s", ur->nice_level, strerror_safe(errno));
else if (debug)
pam_syslog(handle, LOG_DEBUG, "Nice level set, based on user record.");
}
for (int rl = 0; rl < _RLIMIT_MAX; rl++) {
if (!ur->rlimits[rl])
continue;
r = setrlimit_closest(rl, ur->rlimits[rl]);
if (r < 0)
pam_syslog(handle, LOG_ERR, "Failed to set resource limit %s, ignoring: %s", rlimit_to_string(rl), strerror_safe(r));
else if (debug)
pam_syslog(handle, LOG_DEBUG, "Resource limit %s set, based on user record.", rlimit_to_string(rl));
}
return PAM_SUCCESS;
}
static int configure_runtime_directory(
pam_handle_t *handle,
UserRecord *ur,
const char *rt) {
int r;
assert(handle);
assert(ur);
assert(rt);
if (!validate_runtime_directory(handle, rt, ur->uid))
return PAM_SUCCESS;
r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set runtime dir: %s", pam_strerror(handle, r));
return r;
}
return export_legacy_dbus_address(handle, rt);
}
_public_ PAM_EXTERN int pam_sm_open_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
const char
*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, *desktop_pam = NULL,
*memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL, *runtime_max_sec = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
_cleanup_(user_record_unrefp) UserRecord *ur = NULL;
int session_fd = -1, existing, r;
bool debug = false, remote;
uint32_t vtnr = 0;
uid_t original_uid;
assert(handle);
if (parse_argv(handle,
argc, argv,
&class_pam,
&type_pam,
&desktop_pam,
&debug) < 0)
return PAM_SESSION_ERR;
if (debug)
pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
r = acquire_user_record(handle, &ur);
if (r != PAM_SUCCESS)
return r;
/* Make most of this a NOP on non-logind systems */
if (!logind_running())
goto success;
/* 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. */
r = pam_get_item(handle, PAM_SERVICE, (const void**) &service);
if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM service: %s", pam_strerror(handle, r));
return r;
}
if (streq_ptr(service, "systemd-user")) {
char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)];
xsprintf(rt, "/run/user/"UID_FMT, ur->uid);
r = configure_runtime_directory(handle, ur, rt);
if (r != PAM_SUCCESS)
return r;
goto success;
}
/* Otherwise, we ask logind to create a session for us */
r = pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM XDISPLAY: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_item(handle, PAM_TTY, (const void**) &tty);
if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM TTY: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM RUSER: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM RHOST: %s", pam_strerror(handle, r));
return r;
}
seat = getenv_harder(handle, "XDG_SEAT", NULL);
cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
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 is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
* probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
* (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
* off processes.) */
type = "unspecified";
class = "background";
tty = NULL;
} else if (streq(tty, "ssh")) {
/* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
* details look for "PAM_TTY_KLUDGE" in the openssh sources). */
type ="tty";
class = "user";
tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
* associated with a pty — won't be tracked by their tty in logind. This is because ssh
* does the PAM session registration early for new connections, and registers a pty only
* much later (this is because it doesn't know yet if it needs one at all, as whether to
* register a pty or not is negotiated much later in the protocol). */
} else
/* Chop off leading /dev prefix that some clients specify, but others do not. */
tty = skip_dev_prefix(tty);
/* 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))
(void) get_seat_from_display(display, &seat, &vtnr);
else if (streq(seat, "seat0"))
(void) get_seat_from_display(display, NULL, &vtnr);
}
if (seat && !streq(seat, "seat0") && vtnr != 0) {
if (debug)
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);
r = pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM systemd.memory_max data: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_data(handle, "systemd.tasks_max", (const void **)&tasks_max);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM systemd.tasks_max data: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM systemd.cpu_weight data: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_data(handle, "systemd.io_weight", (const void **)&io_weight);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM systemd.io_weight data: %s", pam_strerror(handle, r));
return r;
}
r = pam_get_data(handle, "systemd.runtime_max_sec", (const void **)&runtime_max_sec);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM systemd.runtime_max_sec data: %s", pam_strerror(handle, r));
return r;
}
/* Talk to logind over the message bus */
r = pam_acquire_bus_connection(handle, &bus);
if (r != PAM_SUCCESS)
return r;
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",
ur->uid, getpid_cached(),
strempty(service),
type, class, strempty(desktop),
strempty(seat), vtnr, strempty(tty), strempty(display),
yes_no(remote), strempty(remote_user), strempty(remote_host));
pam_syslog(handle, LOG_DEBUG, "Session limits: "
"memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s runtime_max_sec=%s",
strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight), strna(runtime_max_sec));
}
r = bus_message_new_method_call(bus, &m, bus_login_mgr, "CreateSession");
if (r < 0)
return pam_bus_log_create_error(handle, r);
r = sd_bus_message_append(m, "uusssssussbss",
(uint32_t) ur->uid,
0,
service,
type,
class,
desktop,
seat,
vtnr,
tty,
display,
remote,
remote_user,
remote_host);
if (r < 0)
return pam_bus_log_create_error(handle, r);
r = sd_bus_message_open_container(m, 'a', "(sv)");
if (r < 0)
return pam_bus_log_create_error(handle, r);
r = append_session_memory_max(handle, m, memory_max);
if (r != PAM_SUCCESS)
return r;
r = append_session_runtime_max_sec(handle, m, runtime_max_sec);
if (r != PAM_SUCCESS)
return r;
r = append_session_tasks_max(handle, m, tasks_max);
if (r != PAM_SUCCESS)
return r;
r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
if (r != PAM_SUCCESS)
return r;
r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
if (r != PAM_SUCCESS)
return r;
r = sd_bus_message_close_container(m);
if (r < 0)
return pam_bus_log_create_error(handle, r);
r = sd_bus_call(bus, m, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC, &error, &reply);
if (r < 0) {
if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
if (debug)
pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r));
/* We are already in a session, don't do anything */
goto success;
} else {
pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
return PAM_SESSION_ERR;
}
}
r = sd_bus_message_read(reply,
"soshusub",
&id,
&object_path,
&runtime_path,
&session_fd,
&original_uid,
&seat,
&vtnr,
&existing);
if (r < 0)
return pam_bus_log_parse_error(handle, r);
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 = update_environment(handle, "XDG_SESSION_ID", id);
if (r != PAM_SUCCESS)
return r;
if (original_uid == ur->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 = configure_runtime_directory(handle, ur, runtime_path);
if (r != PAM_SUCCESS)
return r;
}
/* Most likely we got the session/type/class from environment variables, but might have gotten the data
* somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
* data is inherited into the session processes, and programs can rely on them to be initialized. */
r = update_environment(handle, "XDG_SESSION_TYPE", type);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "XDG_SESSION_CLASS", class);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "XDG_SEAT", seat);
if (r != PAM_SUCCESS)
return r;
if (vtnr > 0) {
char buf[DECIMAL_STR_MAX(vtnr)];
sprintf(buf, "%u", vtnr);
r = update_environment(handle, "XDG_VTNR", buf);
if (r != PAM_SUCCESS)
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: %s", pam_strerror(handle, r));
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", FD_TO_PTR(session_fd), NULL);
if (r != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to install session fd: %s", pam_strerror(handle, r));
safe_close(session_fd);
return r;
}
}
success:
r = apply_user_record_settings(handle, ur, debug);
if (r != PAM_SUCCESS)
return r;
/* Let's release the D-Bus connection, after all the session might live quite a long time, and we are
* not going to use the bus connection in that time, so let's better close before the daemon kicks us
* off because we are not processing anything. */
(void) pam_release_bus_connection(handle);
return PAM_SUCCESS;
}
_public_ PAM_EXTERN int pam_sm_close_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
const void *existing = NULL;
bool debug = false;
const char *id;
int r;
assert(handle);
if (parse_argv(handle,
argc, argv,
NULL,
NULL,
NULL,
&debug) < 0)
return PAM_SESSION_ERR;
if (debug)
pam_syslog(handle, LOG_DEBUG, "pam-systemd shutting down");
/* Only release session if it wasn't pre-existing when we
* tried to create it */
r = pam_get_data(handle, "systemd.existing", &existing);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
pam_syslog(handle, LOG_ERR, "Failed to get PAM systemd.existing data: %s", pam_strerror(handle, r));
return r;
}
id = pam_getenv(handle, "XDG_SESSION_ID");
if (id && !existing) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
/* 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 = pam_acquire_bus_connection(handle, &bus);
if (r != PAM_SUCCESS)
return r;
r = bus_call_method(bus, bus_login_mgr, "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;
}
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