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cd8a1a8ef7a4eade1d11e28ccbb2fcd8f39b3f04
systemd/src/login/pam_systemd.c
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <endian.h>
#include <fcntl.h>
#include <pwd.h>
#include <security/pam_misc.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#include "sd-bus.h"
#include "sd-varlink.h"
#include "alloc-util.h"
#include "bus-common-errors.h"
#include "bus-error.h"
#include "bus-internal.h"
#include "bus-locator.h"
#include "capability-list.h"
#include "capability-util.h"
#include "cgroup-setup.h"
#include "chase.h"
#include "creds-util.h"
#include "devnum-util.h"
#include "errno-util.h"
#include "extract-word.h"
#include "fd-util.h"
#include "format-util.h"
#include "fs-util.h"
#include "hostname-util.h"
#include "io-util.h"
#include "json-util.h"
#include "locale-util.h"
#include "login-util.h"
#include "osc-context.h"
#include "pam-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "percent-util.h"
#include "pidfd-util.h"
#include "pidref.h"
#include "process-util.h"
#include "rlimit-util.h"
#include "socket-util.h"
#include "stdio-util.h"
#include "string-util.h"
#include "strv.h"
#include "terminal-util.h"
#include "time-util.h"
#include "tmpfile-util.h"
#include "user-util.h"
#include "userdb.h"
#define LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC (2*USEC_PER_MINUTE)
static int parse_caps(
pam_handle_t *handle,
const char *value,
uint64_t *caps) {
bool subtract;
int r;
assert(handle);
assert(value);
if (value[0] == '~') {
subtract = true;
value++;
} else
subtract = false;
for (;;) {
_cleanup_free_ char *s = NULL;
uint64_t b, m;
int c;
/* We can't use spaces as separators here, as PAM's simplistic argument parser doesn't allow
* spaces inside of arguments. We use commas instead (which is similar to cap_from_text(),
* which also uses commas). */
r = extract_first_word(&value, &s, ",", EXTRACT_DONT_COALESCE_SEPARATORS);
if (r < 0)
return r;
if (r == 0)
break;
c = capability_from_name(s);
if (c < 0) {
pam_syslog(handle, LOG_WARNING, "Unknown capability, ignoring: %s", s);
continue;
}
m = UINT64_C(1) << c;
if (!caps)
continue;
if (*caps == UINT64_MAX)
b = subtract ? all_capabilities() : 0;
else
b = *caps;
if (subtract)
*caps = b & ~m;
else
*caps = b | m;
}
return 0;
}
static int parse_argv(
pam_handle_t *handle,
int argc, const char **argv,
const char **class,
const char **type,
const char **desktop,
const char **area,
bool *debug,
uint64_t *default_capability_bounding_set,
uint64_t *default_capability_ambient_set) {
int r;
assert(handle);
assert(argc >= 0);
assert(argc == 0 || argv);
for (int i = 0; i < 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 ((p = startswith(argv[i], "area="))) {
if (!isempty(p) && !filename_is_valid(p))
pam_syslog(handle, LOG_WARNING, "Area name specified among PAM module parameters is not valid, ignoring: %m");
else if (area)
*area = p;
} else if (streq(argv[i], "debug")) {
if (debug)
*debug = true;
} else if ((p = startswith(argv[i], "debug="))) {
r = parse_boolean(p);
if (r < 0)
pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring: %s", p);
else if (debug)
*debug = r;
} else if ((p = startswith(argv[i], "default-capability-bounding-set="))) {
r = parse_caps(handle, p, default_capability_bounding_set);
if (r < 0)
pam_syslog(handle, LOG_WARNING, "Failed to parse default-capability-bounding-set= argument, ignoring: %s", p);
} else if ((p = startswith(argv[i], "default-capability-ambient-set="))) {
r = parse_caps(handle, p, default_capability_ambient_set);
if (r < 0)
pam_syslog(handle, LOG_WARNING, "Failed to parse default-capability-ambient-set= argument, ignoring: %s", p);
} 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) {
int r;
assert(handle);
const char *username = NULL;
r = pam_get_user(handle, &username, NULL);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get user name: @PAMERR@");
if (isempty(username))
return pam_syslog_pam_error(handle, LOG_ERR, PAM_SERVICE_ERR, "User name not valid.");
/* If pam_systemd_homed (or some other module) already acquired the user record we can reuse it
* here. */
_cleanup_free_ char *field = strjoin("systemd-user-record-", username);
if (!field)
return pam_log_oom(handle);
_cleanup_(user_record_unrefp) UserRecord *ur = NULL;
const char *json = NULL;
r = pam_get_data(handle, field, (const void**) &json);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA))
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM user record data: @PAMERR@");
if (r == PAM_SUCCESS && json) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL;
/* Parse cached record */
r = sd_json_parse(json, SD_JSON_PARSE_SENSITIVE, &v, NULL, NULL);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to parse JSON user record: %m");
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)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to load user record: %m");
/* Safety check if cached record actually matches what we are looking for */
if (!user_record_matches_user_name(ur, username))
return pam_syslog_pam_error(handle, LOG_ERR, PAM_SERVICE_ERR,
"Acquired user record does not match user name.");
} else {
_cleanup_free_ char *formatted = NULL;
/* Request the record ourselves */
r = userdb_by_name(username, /* match= */ NULL, /* flags= */ 0, &ur);
if (r < 0) {
pam_syslog_errno(handle, LOG_ERR, r, "Failed to get user record: %m");
return PAM_USER_UNKNOWN;
}
if (!uid_is_valid(ur->uid)) {
pam_syslog_errno(handle, LOG_ERR, r, "User record of user '%s' has no UID, refusing: %m", username);
return PAM_USER_UNKNOWN;
}
r = sd_json_variant_format(ur->json, 0, &formatted);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to format user JSON: %m");
/* And cache it for everyone else */
r = pam_set_data(handle, field, formatted, pam_cleanup_free);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to set PAM user record data '%s': @PAMERR@", field);
TAKE_PTR(formatted);
}
if (!uid_is_valid(ur->uid))
return pam_syslog_pam_error(handle, LOG_ERR, PAM_SERVICE_ERR,
"Acquired user record does not have a UID.");
if (ret_record)
*ret_record = TAKE_PTR(ur);
return PAM_SUCCESS;
}
static bool display_is_local(const char *display) {
assert(display);
return
display[0] == ':' &&
ascii_isdigit(display[1]);
}
static int socket_from_display(const char *display) {
_cleanup_free_ char *f = NULL;
size_t k;
char *c;
union sockaddr_union sa;
socklen_t sa_len;
_cleanup_close_ int fd = -EBADF;
int r;
assert(display);
if (!display_is_local(display))
return -EINVAL;
k = strspn(display+1, "0123456789");
/* Try abstract socket first. */
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;
r = sockaddr_un_set_path(&sa.un, f);
if (r < 0)
return r;
sa_len = r;
fd = RET_NERRNO(socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0));
if (fd < 0)
return fd;
r = RET_NERRNO(connect(fd, &sa.sa, sa_len));
if (r >= 0)
return TAKE_FD(fd);
if (r != -ECONNREFUSED)
return r;
/* Try also non-abstract socket. */
r = sockaddr_un_set_path(&sa.un, f + 1);
if (r < 0)
return r;
sa_len = r;
r = RET_NERRNO(connect(fd, &sa.sa, sa_len));
if (r >= 0)
return TAKE_FD(fd);
return r;
}
static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
_cleanup_free_ char *sys_path = NULL, *tty = NULL;
_cleanup_close_ int fd = -EBADF;
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. */
fd = socket_from_display(display);
if (fd < 0)
return fd;
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/" DEVNUM_FORMAT_STR, DEVNUM_FORMAT_VAL(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;
assert(v > 0);
if (seat)
*seat = "seat0";
*vtnr = (uint32_t) v;
return 0;
}
static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
int r;
assert(handle);
assert(m);
if (isempty(limit))
return 0;
if (streq(limit, "infinity"))
return sd_bus_message_append(m, "(sv)", "MemoryMax", "t", UINT64_MAX);
r = parse_permyriad(limit);
if (r >= 0)
return sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", UINT32_SCALE_FROM_PERMYRIAD(r));
uint64_t val;
r = parse_size(limit, 1024, &val);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max, ignoring: %s", limit);
return PAM_SUCCESS;
}
return sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
}
static int append_session_runtime_max_sec(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
int r;
assert(handle);
assert(m);
/* No need to parse "infinity" here, it will be set by default later in scope_init() */
if (isempty(limit) || streq(limit, "infinity"))
return 0;
usec_t val;
r = parse_sec(limit, &val);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.runtime_max_sec: %s, ignoring.", limit);
return 0;
}
return sd_bus_message_append(m, "(sv)", "RuntimeMaxUSec", "t", (uint64_t) val);
}
static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
int r;
assert(handle);
assert(m);
/* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
if (isempty(limit) || streq(limit, "infinity"))
return 0;
uint64_t val;
r = safe_atou64(limit, &val);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max, ignoring: %s", limit);
return 0;
}
return sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
}
static int append_session_cpu_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
int r;
assert(handle);
assert(m);
if (isempty(limit))
return 0;
uint64_t val;
r = cg_cpu_weight_parse(limit, &val);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight, ignoring: %s", limit);
return 0;
}
return sd_bus_message_append(m, "(sv)", "CPUWeight", "t", val);
}
static int append_session_io_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
int r;
assert(handle);
assert(m);
if (isempty(limit))
return 0;
uint64_t val;
r = cg_weight_parse(limit, &val);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight, ignoring: %s", limit);
return 0;
}
return sd_bus_message_append(m, "(sv)", "IOWeight", "t", val);
}
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 bool getenv_harder_bool(pam_handle_t *handle, const char *key, bool fallback) {
const char *v;
int r;
assert(handle);
assert(key);
v = getenv_harder(handle, key, NULL);
if (isempty(v))
return fallback;
r = parse_boolean(v);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse environment variable value '%s' of '%s', falling back to using '%s'.", v, key, true_false(fallback));
return fallback;
}
return r;
}
static uint32_t getenv_harder_uint32(pam_handle_t *handle, const char *key, uint32_t fallback) {
int r;
assert(handle);
assert(key);
const char *v = getenv_harder(handle, key, NULL);
if (isempty(v))
return fallback;
uint32_t u;
r = safe_atou32(v, &u);
if (r < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to parse environment variable value '%s' of '%s' as unsigned integer, falling back to using %" PRIu32 ".", v, key, fallback);
return fallback;
}
return u;
}
static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
int r;
assert(handle);
assert(key);
/* Updates the environment, and removes environment variables if value is NULL or empty. Also, log
* about errors. */
if (isempty(value)) {
/* Unset the variable if set. Note that pam_putenv() would log nastily behind our back if we
* call it without the variable actually being set. Hence we check explicitly if it's set
* before. */
if (!pam_getenv(handle, key))
return PAM_SUCCESS;
r = pam_putenv(handle, key);
if (!IN_SET(r, PAM_SUCCESS, PAM_BAD_ITEM))
return pam_syslog_pam_error(handle, LOG_WARNING, r,
"Failed to unset %s environment variable: @PAMERR@", key);
return PAM_SUCCESS;
}
r = pam_misc_setenv(handle, key, value, /* readonly= */ false);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to set environment variable %s: @PAMERR@", key);
return PAM_SUCCESS;
}
static int propagate_credential_to_environment(pam_handle_t *handle, const char *credential, const char *varname) {
int r;
assert(handle);
assert(credential);
assert(varname);
_cleanup_free_ char *value = NULL;
/* Read a service credential, and propagate it into an environment variable */
r = read_credential(credential, (void**) &value, /* ret_size= */ NULL);
if (r < 0) {
log_debug_errno(r, "Failed to read credential '%s', ignoring: %m", credential);
return PAM_SUCCESS;
}
r = pam_misc_setenv(handle, varname, value, 0);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to set environment variable %s: @PAMERR@", varname);
return PAM_SUCCESS;
}
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_errno(handle, LOG_ERR, errno, "Failed to stat() runtime directory '%s': %m", path);
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)
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to set PAM environment variable %s: @PAMERR@", e);
pam_debug_syslog(handle, 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,
uint64_t default_capability_bounding_set,
uint64_t default_capability_ambient_set) {
_cleanup_strv_free_ char **langs = NULL;
int r;
assert(handle);
assert(ur);
if (ur->umask != MODE_INVALID) {
umask(ur->umask);
pam_debug_syslog(handle, debug, "Set user umask to %04o based on user record.", ur->umask);
}
STRV_FOREACH(i, ur->environment) {
r = pam_putenv_and_log(handle, *i, debug);
if (r != PAM_SUCCESS)
return r;
}
if (ur->email_address) {
_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 (!timezone_is_valid(ur->time_zone, LOG_DEBUG))
pam_debug_syslog(handle, 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;
}
}
r = user_record_languages(ur, &langs);
if (r < 0)
pam_syslog_errno(handle, LOG_ERR, r,
"Failed to acquire user's language preferences, ignoring: %m");
else if (strv_isempty(langs))
; /* User has no preference set so we do nothing */
else if (locale_is_installed(langs[0]) <= 0)
pam_debug_syslog(handle, debug,
"Preferred languages specified in user record are not installed locally, not setting $LANG or $LANGUAGE.");
else {
_cleanup_free_ char *lang = NULL;
lang = strjoin("LANG=", langs[0]);
if (!lang)
return pam_log_oom(handle);
r = pam_putenv_and_log(handle, lang, debug);
if (r != PAM_SUCCESS)
return r;
if (strv_length(langs) > 1) {
_cleanup_free_ char *joined = NULL, *language = NULL;
joined = strv_join(langs, ":");
if (!joined)
return pam_log_oom(handle);
language = strjoin("LANGUAGE=", joined);
if (!language)
return pam_log_oom(handle);
r = pam_putenv_and_log(handle, language, debug);
if (r != PAM_SUCCESS)
return r;
}
}
if (nice_is_valid(ur->nice_level)) {
if (nice(ur->nice_level) < 0)
pam_syslog_errno(handle, LOG_WARNING, errno,
"Failed to set nice level to %i, ignoring: %m", ur->nice_level);
else
pam_debug_syslog(handle, debug,
"Nice level set to %i, based on user record.", ur->nice_level);
}
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_errno(handle, LOG_ERR, r,
"Failed to set resource limit %s, ignoring: %m", rlimit_to_string(rl));
else
pam_debug_syslog(handle, debug,
"Resource limit %s set, based on user record.", rlimit_to_string(rl));
}
uint64_t a, b;
a = user_record_capability_ambient_set(ur);
if (a == UINT64_MAX)
a = default_capability_ambient_set;
b = user_record_capability_bounding_set(ur);
if (b == UINT64_MAX)
b = default_capability_bounding_set;
if (a != UINT64_MAX && a != 0) {
a &= b;
r = capability_ambient_set_apply(a, /* also_inherit= */ true);
if (r < 0)
pam_syslog_errno(handle, LOG_ERR, r,
"Failed to set ambient capabilities, ignoring: %m");
}
if (b != UINT64_MAX && !cap_test_all(b)) {
r = capability_bounding_set_drop(b, /* right_now= */ false);
if (r < 0)
pam_syslog_errno(handle, LOG_ERR, r,
"Failed to set bounding capabilities, ignoring: %m");
}
return PAM_SUCCESS;
}
static uint64_t pick_default_capability_ambient_set(
UserRecord *ur,
const char *service,
const char *seat) {
/* If not configured otherwise, let's enable CAP_WAKE_ALARM for regular users when logging in on a
* seat (i.e. when they are present physically on the device), or when invoked for the systemd --user
* instances. This allows desktops to install CAP_WAKE_ALARM to implement alarm clock apps without
* much fuss. */
return ur &&
user_record_disposition(ur) == USER_REGULAR &&
(streq_ptr(service, "systemd-user") || !isempty(seat)) ? (UINT64_C(1) << CAP_WAKE_ALARM) : UINT64_MAX;
}
typedef struct SessionContext {
const char *service;
const char *type;
const char *class;
const char *desktop;
const char *seat;
uint32_t vtnr;
const char *tty;
const char *display;
bool remote;
const char *remote_user;
const char *remote_host;
const char *memory_max;
const char *tasks_max;
const char *cpu_weight;
const char *io_weight;
const char *runtime_max_sec;
const char *area;
bool incomplete;
} SessionContext;
static int create_session_message(
sd_bus *bus,
pam_handle_t *handle,
UserRecord *ur,
const SessionContext *context,
bool avoid_pidfd,
sd_bus_message **ret) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
_cleanup_close_ int pidfd = -EBADF;
int r;
assert(bus);
assert(handle);
assert(ur);
assert(context);
assert(ret);
if (!avoid_pidfd) {
pidfd = pidfd_open(getpid_cached(), 0);
if (pidfd < 0)
return -errno;
}
r = bus_message_new_method_call(bus, &m, bus_login_mgr, pidfd >= 0 ? "CreateSessionWithPIDFD" : "CreateSession");
if (r < 0)
return r;
r = sd_bus_message_append(
m,
pidfd >= 0 ? "uhsssssussbss" : "uusssssussbss",
(uint32_t) ur->uid,
pidfd >= 0 ? pidfd : 0,
context->service,
context->type,
context->class,
context->desktop,
context->seat,
context->vtnr,
context->tty,
context->display,
context->remote,
context->remote_user,
context->remote_host);
if (r < 0)
return r;
if (pidfd >= 0) {
r = sd_bus_message_append(m, "t", UINT64_C(0));
if (r < 0)
return r;
}
r = sd_bus_message_open_container(m, 'a', "(sv)");
if (r < 0)
return r;
r = append_session_memory_max(handle, m, context->memory_max);
if (r < 0)
return r;
r = append_session_runtime_max_sec(handle, m, context->runtime_max_sec);
if (r < 0)
return r;
r = append_session_tasks_max(handle, m, context->tasks_max);
if (r < 0)
return r;
r = append_session_cpu_weight(handle, m, context->cpu_weight);
if (r < 0)
return r;
r = append_session_io_weight(handle, m, context->io_weight);
if (r < 0)
return r;
r = sd_bus_message_close_container(m);
if (r < 0)
return r;
*ret = TAKE_PTR(m);
return 0;
}
static void session_context_mangle(
pam_handle_t *handle,
SessionContext *c,
UserRecord *ur,
bool debug) {
assert(handle);
assert(c);
assert(ur);
if (streq_ptr(c->service, "systemd-user")) {
/* If we detect that we are running in the "systemd-user" PAM stack, then let's patch the class to
* 'manager' if not set, simply for robustness reasons. */
c->type = "unspecified";
c->class = IN_SET(user_record_disposition(ur), USER_INTRINSIC, USER_SYSTEM, USER_DYNAMIC) ?
"manager-early" : "manager";
c->tty = NULL;
} else if (c->tty && strchr(c->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(c->display))
c->display = c->tty;
c->tty = NULL;
} else if (streq_ptr(c->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.) */
c->type = "unspecified";
c->class = "background";
c->tty = NULL;
} else if (streq_ptr(c->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). */
c->type = "tty";
c->class = "user";
c->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 if (c->tty)
/* Chop off leading /dev prefix that some clients specify, but others do not. */
c->tty = skip_dev_prefix(c->tty);
if (!isempty(c->display) && !c->vtnr) {
if (isempty(c->seat))
(void) get_seat_from_display(c->display, &c->seat, &c->vtnr);
else if (streq(c->seat, "seat0"))
(void) get_seat_from_display(c->display, /* seat= */ NULL, &c->vtnr);
}
if (c->seat && !streq(c->seat, "seat0") && c->vtnr != 0) {
pam_debug_syslog(handle, debug, "Ignoring vtnr %"PRIu32" for %s which is not seat0", c->vtnr, c->seat);
c->vtnr = 0;
}
if (isempty(c->type)) {
c->type = !isempty(c->display) ? "x11" :
!isempty(c->tty) ? "tty" : "unspecified";
pam_debug_syslog(handle, debug, "Automatically chose session type '%s'.", c->type);
}
if (!c->area)
c->area = ur->default_area;
if (!isempty(c->area) && !filename_is_valid(c->area)) {
pam_syslog(handle, LOG_WARNING, "Specified area '%s' is not a valid filename, ignoring area request.", c->area);
c->area = NULL;
}
if (isempty(c->class)) {
c->class = streq(c->type, "unspecified") ? "background" : "user";
/* For non-regular users tweak the type a bit:
*
* - Allow root tty logins *before* systemd-user-sessions.service is run, to allow early boot
* logins to debug things.
*
* - Non-graphical sessions shall be invoked without service manager.
*
* (Note that this somewhat replicates the class mangling logic on systemd-logind.service's
* server side to some degree, in case clients allocate a session and don't specify a
* class. This is somewhat redundant, but we need the class set up properly below.)
*
* For regular users also tweak the type a bit: if an area is specified at login time, switch
* to light mode too. (Mostly because at the moment we do no support a per-area service
* manager. Once we do, we should change this.).
*/
switch (user_record_disposition(ur)) {
case USER_INTRINSIC:
case USER_SYSTEM:
case USER_DYNAMIC:
if (streq(c->class, "user"))
c->class = user_record_is_root(ur) ? "user-early" :
(STR_IN_SET(c->type, "x11", "wayland", "mir") ? "user" : "user-light");
else if (streq(c->class, "background"))
c->class = "background-light";
break;
case USER_REGULAR:
if (!isempty(c->area)) {
if (streq(c->class, "user"))
c->class = "user-light";
else if (streq(c->class, "background"))
c->class = "background-light";
}
break;
default:
;
}
pam_debug_syslog(handle, debug, "Automatically chose session class '%s'.", c->class);
}
if (c->incomplete) {
if (streq(c->class, "user"))
c->class = "user-incomplete";
else
pam_syslog(handle, LOG_WARNING, "PAM session of class '%s' is incomplete, which is not supported, ignoring.", c->class);
}
c->remote = !isempty(c->remote_host) && !is_localhost(c->remote_host);
}
static bool can_use_varlink(const SessionContext *c) {
/* Since PID 1 currently doesn't do Varlink right now, we cannot directly set properties for the
* scope, for now. */
return !c->memory_max &&
!c->runtime_max_sec &&
!c->tasks_max &&
!c->cpu_weight &&
!c->io_weight;
}
static int register_session(
pam_handle_t *handle,
SessionContext *c,
UserRecord *ur,
bool debug,
char **ret_seat,
char **ret_type,
char **ret_runtime_dir) {
int r;
assert(handle);
assert(c);
assert(ur);
assert(ret_seat);
assert(ret_type);
assert(ret_runtime_dir);
/* We don't register session class none with logind */
if (streq(c->class, "none")) {
pam_debug_syslog(handle, debug, "Skipping logind registration for session class none.");
*ret_seat = *ret_type = *ret_runtime_dir = NULL;
return PAM_SUCCESS;
}
/* Make most of this a NOP on non-logind systems */
if (!logind_running()) {
pam_debug_syslog(handle, debug, "Skipping logind registration as logind is not running.");
*ret_seat = *ret_type = *ret_runtime_dir = NULL;
return PAM_SUCCESS;
}
pam_debug_syslog(handle, 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(c->service),
c->type, c->class, strempty(c->desktop),
strempty(c->seat), c->vtnr, strempty(c->tty), strempty(c->display),
yes_no(c->remote), strempty(c->remote_user), strempty(c->remote_host));
pam_debug_syslog(handle, debug,
"Session limits: "
"memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s runtime_max_sec=%s",
strna(c->memory_max), strna(c->tasks_max), strna(c->cpu_weight), strna(c->io_weight), strna(c->runtime_max_sec));
_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL; /* the following variables point into this message, hence pin it for longer */
_cleanup_(sd_varlink_unrefp) sd_varlink *vl = NULL; /* similar */
const char *id = NULL, *object_path = NULL, *runtime_path = NULL, *real_seat = NULL;
int existing = false;
uint32_t original_uid = UID_INVALID, real_vtnr = 0;
bool done = false;
if (can_use_varlink(c)) {
r = sd_varlink_connect_address(&vl, "/run/systemd/io.systemd.Login");
if (r < 0)
log_debug_errno(r, "Failed to connect to logind via Varlink, falling back to D-Bus: %m");
else {
r = sd_varlink_set_allow_fd_passing_output(vl, true);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to enable output fd passing on Varlink socket: %m");
r = sd_varlink_set_relative_timeout(vl, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to set relative timeout on Varlink socket: %m");
_cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
r = pidref_set_self(&pidref);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to acquire PID reference on ourselves: %m");
sd_json_variant *vreply = NULL;
const char *error_id = NULL;
r = sd_varlink_callbo(
vl,
"io.systemd.Login.CreateSession",
&vreply,
&error_id,
SD_JSON_BUILD_PAIR_UNSIGNED("UID", ur->uid),
JSON_BUILD_PAIR_PIDREF("PID", &pidref),
JSON_BUILD_PAIR_STRING_NON_EMPTY("Service", c->service),
SD_JSON_BUILD_PAIR("Type", JSON_BUILD_STRING_UNDERSCORIFY(c->type)),
SD_JSON_BUILD_PAIR("Class", JSON_BUILD_STRING_UNDERSCORIFY(c->class)),
JSON_BUILD_PAIR_STRING_NON_EMPTY("Desktop", c->desktop),
JSON_BUILD_PAIR_STRING_NON_EMPTY("Seat", c->seat),
SD_JSON_BUILD_PAIR_CONDITION(c->vtnr > 0, "VTNr", SD_JSON_BUILD_UNSIGNED(c->vtnr)),
JSON_BUILD_PAIR_STRING_NON_EMPTY("TTY", c->tty),
JSON_BUILD_PAIR_STRING_NON_EMPTY("Display", c->display),
SD_JSON_BUILD_PAIR_BOOLEAN("Remote", c->remote),
JSON_BUILD_PAIR_STRING_NON_EMPTY("RemoteUser", c->remote_user),
JSON_BUILD_PAIR_STRING_NON_EMPTY("RemoteHost", c->remote_host));
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r,
"Failed to issue io.systemd.Login.CreateSession varlink call: %m");
if (streq_ptr(error_id, "io.systemd.Login.AlreadySessionMember")) {
/* We are already in a session, don't do anything */
pam_debug_syslog(handle, debug, "Not creating session: %s", error_id);
*ret_seat = *ret_type= *ret_runtime_dir = NULL;
return PAM_SUCCESS;
}
if (error_id)
return pam_syslog_errno(handle, LOG_ERR, sd_varlink_error_to_errno(error_id, vreply),
"Varlink call io.systemd.Login.CreateSession failed: %s", error_id);
struct {
const char *id;
const char *runtime_path;
uid_t uid;
const char *seat;
unsigned vtnr;
bool existing;
} p = {
.uid = UID_INVALID,
};
static const sd_json_dispatch_field dispatch_table[] = {
{ "Id", SD_JSON_VARIANT_STRING, sd_json_dispatch_const_string, voffsetof(p, id), SD_JSON_MANDATORY },
{ "RuntimePath", SD_JSON_VARIANT_STRING, json_dispatch_const_path, voffsetof(p, runtime_path), SD_JSON_MANDATORY },
{ "UID", _SD_JSON_VARIANT_TYPE_INVALID, sd_json_dispatch_uid_gid, voffsetof(p, uid), SD_JSON_MANDATORY },
{ "Seat", SD_JSON_VARIANT_STRING, sd_json_dispatch_const_string, voffsetof(p, seat), 0 },
{ "VTNr", _SD_JSON_VARIANT_TYPE_INVALID, sd_json_dispatch_uint, voffsetof(p, vtnr), 0 },
{}
};
r = sd_json_dispatch(vreply, dispatch_table, SD_JSON_ALLOW_EXTENSIONS, &p);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to parse CreateSession() reply: %m");
id = p.id;
runtime_path = p.runtime_path;
original_uid = p.uid;
real_seat = p.seat;
real_vtnr = p.vtnr;
existing = false; /* Even on D-Bus logind only returns false these days */
done = true;
}
}
if (!done) {
/* Let's release the D-Bus connection once we are done here, after all the session might live
* quite a long time, and we are not going to process the bus connection in that time, so
* let's better close before the daemon kicks us off because we are not processing
* anything. */
_cleanup_(pam_bus_data_disconnectp) PamBusData *d = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
/* Talk to logind over the message bus */
r = pam_acquire_bus_connection(handle, "pam-systemd", debug, &bus, &d);
if (r != PAM_SUCCESS)
return r;
_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
r = create_session_message(
bus,
handle,
ur,
c,
/* avoid_pidfd = */ false,
&m);
if (r < 0)
return pam_bus_log_create_error(handle, r);
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
r = sd_bus_call(bus, m, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC, &error, &reply);
if (r < 0 && sd_bus_error_has_name(&error, SD_BUS_ERROR_UNKNOWN_METHOD)) {
sd_bus_error_free(&error);
pam_debug_syslog(handle, debug,
"CreateSessionWithPIDFD() API is not available, retrying with CreateSession().");
m = sd_bus_message_unref(m);
r = create_session_message(bus,
handle,
ur,
c,
/* avoid_pidfd = */ true,
&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)) {
/* We are already in a session, don't do anything */
pam_debug_syslog(handle, debug,
"Not creating session: %s", bus_error_message(&error, r));
*ret_seat = *ret_type = *ret_runtime_dir = NULL;
return PAM_SUCCESS;
}
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 = */ NULL,
&original_uid,
&real_seat,
&real_vtnr,
&existing);
if (r < 0)
return pam_bus_log_parse_error(handle, r);
}
pam_debug_syslog(handle, debug,
"Reply from logind: "
"id=%s object_path=%s runtime_path=%s seat=%s vtnr=%u original_uid=%u",
id, strna(object_path), runtime_path, real_seat, real_vtnr, original_uid);
/* Please update manager_default_environment() in core/manager.c accordingly if more session envvars
* shall be added. */
r = update_environment(handle, "XDG_SESSION_ID", id);
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. */
_cleanup_free_ char *real_type = strdup(c->type); /* make copy because this might point to env block, which we are going to update shortly */
if (!real_type)
return pam_log_oom(handle);
r = update_environment(handle, "XDG_SESSION_TYPE", c->type);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "XDG_SESSION_CLASS", c->class);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "XDG_SESSION_DESKTOP", c->desktop);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "XDG_SEAT", real_seat);
if (r != PAM_SUCCESS)
return r;
if (real_vtnr > 0) {
char buf[DECIMAL_STR_MAX(real_vtnr)];
xsprintf(buf, "%u", real_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)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to install existing flag: @PAMERR@");
/* 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. */
_cleanup_free_ char *rt = NULL;
if (original_uid == ur->uid && validate_runtime_directory(handle, runtime_path, ur->uid))
if (strdup_to(&rt, runtime_path) < 0)
return pam_log_oom(handle);
/* Everything worked, hence let's patch in the data we learned. Since 'real_set' points into the
* D-Bus message, let's copy it and return it as a buffer */
_cleanup_free_ char *rs = NULL;
if (strdup_to(&rs, real_seat) < 0)
return pam_log_oom(handle);
c->vtnr = real_vtnr;
c->seat = *ret_seat = TAKE_PTR(rs);
c->type = *ret_type = TAKE_PTR(real_type);
*ret_runtime_dir = TAKE_PTR(rt);
return PAM_SUCCESS;
}
static int import_shell_credentials(pam_handle_t *handle) {
static const char *const propagate[] = {
"shell.prompt.prefix", "SHELL_PROMPT_PREFIX",
"shell.prompt.suffix", "SHELL_PROMPT_SUFFIX",
"shell.welcome", "SHELL_WELCOME",
NULL
};
int r;
assert(handle);
STRV_FOREACH_PAIR(k, v, propagate) {
r = propagate_credential_to_environment(handle, *k, *v);
if (r != PAM_SUCCESS)
return r;
}
return PAM_SUCCESS;
}
static int mkdir_chown_open_directory(
int parent_fd,
const char *name,
uid_t uid,
gid_t gid,
mode_t mode) {
_cleanup_free_ char *t = NULL;
int r;
assert(parent_fd >= 0);
assert(name);
assert(uid_is_valid(uid));
assert(gid_is_valid(gid));
assert(mode != MODE_INVALID);
for (unsigned attempt = 0;; attempt++) {
_cleanup_close_ int fd = openat(parent_fd, name, O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW);
if (fd >= 0)
return TAKE_FD(fd);
if (errno != ENOENT)
return -errno;
/* Let's create the directory under a temporary name first, since we want to make sure that
* once it appears under the right name it has the right ownership */
r = tempfn_random(name, /* extra= */ NULL, &t);
if (r < 0)
return r;
fd = open_mkdir_at(parent_fd, t, O_CLOEXEC|O_EXCL, 0700); /* Use restrictive mode until ownership is in order */
if (fd < 0)
return fd;
r = RET_NERRNO(fchown(fd, uid, gid));
if (r < 0)
goto fail;
r = RET_NERRNO(fchmod(fd, mode));
if (r < 0)
goto fail;
r = rename_noreplace(parent_fd, t, parent_fd, name);
if (r >= 0)
return TAKE_FD(fd);
if (r != -EEXIST || attempt >= 5)
goto fail;
/* Maybe some other login attempt created the directory at the same time? Let's retry */
(void) unlinkat(parent_fd, t, AT_REMOVEDIR);
t = mfree(t);
}
fail:
(void) unlinkat(parent_fd, ASSERT_PTR(t), AT_REMOVEDIR);
return r;
}
static int make_area_runtime_directory(
pam_handle_t *handle,
UserRecord *ur,
const char *runtime_directory,
const char *area,
char **ret) {
assert(handle);
assert(ur);
assert(runtime_directory);
assert(area);
assert(ret);
/* Let's be careful with creating these directories, the runtime directory is owned by the user after all,
* and they might play symlink games with us. */
_cleanup_close_ int fd = open(runtime_directory, O_CLOEXEC|O_PATH|O_DIRECTORY);
if (fd < 0)
return pam_syslog_errno(handle, LOG_ERR, errno, "Unable to open runtime directory '%s': %m", runtime_directory);
_cleanup_close_ int fd_areas = mkdir_chown_open_directory(fd, "Areas", ur->uid, user_record_gid(ur), 0755);
if (fd_areas < 0)
return pam_syslog_errno(handle, LOG_ERR, fd_areas, "Unable to create 'Areas' directory below '%s': %m", runtime_directory);
_cleanup_close_ int fd_area = mkdir_chown_open_directory(fd_areas, area, ur->uid, user_record_gid(ur), 0755);
if (fd_area < 0)
return pam_syslog_errno(handle, LOG_ERR, fd_area, "Unable to create '%s' directory below '%s/Areas': %m", area, runtime_directory);
char *j = path_join(runtime_directory, "Areas", area);
if (!j)
return pam_log_oom(handle);
*ret = j;
return 0;
}
static int export_legacy_dbus_address(
pam_handle_t *handle,
const char *runtime) {
assert(handle);
assert(runtime);
/* 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. */
const char *s = strjoina(runtime, "/bus");
if (access(s, F_OK) < 0) {
if (errno != ENOENT)
pam_syslog_errno(handle, LOG_WARNING, errno, "Failed to check if %s/bus exists, ignoring: %m", runtime);
return PAM_SUCCESS;
}
_cleanup_free_ char *t = NULL;
if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
return pam_log_oom(handle);
return update_environment(handle, "DBUS_SESSION_BUS_ADDRESS", t);
}
static int setup_runtime_directory(
pam_handle_t *handle,
UserRecord *ur,
const char *runtime_directory,
const char *area) {
int r;
assert(handle);
assert(ur);
if (!runtime_directory) {
/* If this is an area switch request, always reset $XDG_RUNTIME_DIR if we got nothing
* to ensure the main runtime dir won't be clobbered. */
if (area)
return update_environment(handle, "XDG_RUNTIME_DIR", NULL);
return PAM_SUCCESS;
}
/* Also create a per-area subdirectory for $XDG_RUNTIME_DIR, so that each area has their own
* set of runtime services. We follow the same directory structure as for $HOME. Note that we
* do not define any form of automatic clean-up for the per-area subdirs beyond the regular
* clean-up of the whole $XDG_RUNTIME_DIR hierarchy when the user finally logs out. */
_cleanup_free_ char *per_area_runtime_directory = NULL;
if (area) {
r = make_area_runtime_directory(handle, ur, runtime_directory, area, &per_area_runtime_directory);
if (r != PAM_SUCCESS)
return r;
runtime_directory = per_area_runtime_directory;
}
r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_directory);
if (r != PAM_SUCCESS)
return r;
return export_legacy_dbus_address(handle, runtime_directory);
}
static int setup_environment(
pam_handle_t *handle,
UserRecord *ur,
const char *runtime_directory,
const char *area,
bool debug) {
int r;
assert(handle);
assert(ur);
const char *h = ASSERT_PTR(user_record_home_directory(ur));
/* If an empty area string is specified, this means an explicit: do not use the area logic, normalize this here */
area = empty_to_null(area);
_cleanup_free_ char *ha = NULL, *area_copy = NULL;
if (area) {
_cleanup_free_ char *j = path_join(h, "Areas", area);
if (!j)
return pam_log_oom(handle);
_cleanup_close_ int fd = -EBADF;
r = chase(j, /* root= */ NULL, CHASE_MUST_BE_DIRECTORY, &ha, &fd);
if (r < 0) {
/* Log the precise error */
pam_syslog_errno(handle, LOG_WARNING, r, "Path '%s' of requested user area '%s' is not accessible, reverting to regular home directory: %m", j, area);
/* Also tell the user directly at login, but a bit more vague */
pam_info(handle, "Path '%s' of requested user area '%s' is not accessible, reverting to regular home directory.", j, area);
area = NULL;
} else {
/* Validate that the target is definitely owned by user */
struct stat st;
if (fstat(fd, &st) < 0)
return pam_syslog_errno(handle, LOG_ERR, errno, "Unable to fstat() target area directory '%s': %m", ha);
if (st.st_uid != ur->uid) {
pam_syslog(handle, LOG_ERR, "Path '%s' of requested user area '%s' is not owned by user, reverting to regular home directory.", ha, area);
/* Also tell the user directly at login. */
pam_info(handle, "Path '%s' of requested user area '%s' is not owned by user, reverting to regular home directory.", ha, area);
area = NULL;
} else {
/* All good, now make a copy of the area string, since we quite likely are
* going to invalidate it (if it points into the environment block), via the
* update_environment() call below */
area_copy = strdup(area);
if (!area_copy)
return pam_log_oom(handle);
pam_debug_syslog(handle, debug, "Area '%s' selected, setting $HOME to '%s'.", area, ha);
h = ha;
area = area_copy;
}
}
}
r = update_environment(handle, "XDG_AREA", area);
if (r != PAM_SUCCESS)
return r;
r = update_environment(handle, "HOME", h);
if (r != PAM_SUCCESS)
return r;
return setup_runtime_directory(handle, ur, runtime_directory, area);
}
static int open_osc_context(pam_handle_t *handle, const char *session_type, UserRecord *ur) {
int r;
assert(handle);
assert(ur);
/* If this is a TTY session, then output the session start OSC sequence */
if (!streq_ptr(session_type, "tty"))
return PAM_SUCCESS;
const char *e = pam_getenv(handle, "TERM");
if (!e)
e = getenv("TERM");
if (streq_ptr(e, "dumb"))
return PAM_SUCCESS;
/* NB: we output directly to stdout, instead of going via pam_info() or so, because that's too
* high-level for us, as it suffixes the output with a newline, expecting a full blown text message
* as prompt string, not just an ANSI sequence. Note that PAM's conv_misc() actually goes to stdout
* anyway, hence let's do so here too, but only after careful validation. */
if (!isatty_safe(STDOUT_FILENO))
return PAM_SUCCESS;
/* Keep a reference to the TTY we are operating on, so that we can issue the OSC close sequence also
* if the TTY is already closed. We use an O_PATH reference here, rather than a properly opened fd,
* so that we don't delay tty hang-up. */
_cleanup_close_ int tty_opath_fd = fd_reopen(STDOUT_FILENO, O_PATH|O_CLOEXEC);
if (tty_opath_fd < 0)
pam_syslog_errno(handle, LOG_DEBUG, tty_opath_fd, "Failed to pin TTY, ignoring: %m");
else
tty_opath_fd = fd_move_above_stdio(tty_opath_fd);
_cleanup_free_ char *osc = NULL;
sd_id128_t osc_id;
r = osc_context_open_session(
ur->user_name,
pam_getenv(handle, "XDG_SESSION_ID"),
&osc,
&osc_id);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to prepare OSC sequence: %m");
r = loop_write(STDOUT_FILENO, osc, SIZE_MAX);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to write OSC sequence to TTY: %m");
/* Remember the OSC context id, so that we can close it cleanly later */
_cleanup_free_ sd_id128_t *osc_id_copy = newdup(sd_id128_t, &osc_id, 1);
if (!osc_id_copy)
return pam_log_oom(handle);
r = pam_set_data(handle, "systemd.osc-context-id", osc_id_copy, pam_cleanup_free);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to set PAM OSC sequence ID data: @PAMERR@");
TAKE_PTR(osc_id_copy);
if (tty_opath_fd >= 0) {
r = pam_set_data(handle, "systemd.osc-context-fd", FD_TO_PTR(tty_opath_fd), pam_cleanup_close);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to set PAM OSC sequence fd data: @PAMERR@");
TAKE_FD(tty_opath_fd);
}
return PAM_SUCCESS;
}
static int close_osc_context(pam_handle_t *handle) {
int r;
assert(handle);
const void *p;
int tty_opath_fd = -EBADF;
r = pam_get_data(handle, "systemd.osc-context-fd", &p);
if (r == PAM_SUCCESS)
tty_opath_fd = PTR_TO_FD(p);
else if (r != PAM_NO_MODULE_DATA)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM OSC context fd: @PAMERR@");
if (tty_opath_fd < 0)
return PAM_SUCCESS;
const sd_id128_t *osc_id = NULL;
r = pam_get_data(handle, "systemd.osc-context-id", (const void**) &osc_id);
if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA))
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM OSC context id data: @PAMERR@");
if (!osc_id)
return PAM_SUCCESS;
/* Now open the original TTY again, so that we can write on it */
_cleanup_close_ int fd = fd_reopen(tty_opath_fd, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (fd < 0) {
pam_syslog_errno(handle, LOG_DEBUG, fd, "Failed to reopen TTY, ignoring: %m");
return PAM_SUCCESS;
}
/* /bin/login calls us with fds 0, 1, 2 closed, which is just weird. Let's step outside of that
* range, just in case pam_syslog() or so logs to stderr */
fd = fd_move_above_stdio(fd);
/* Safety check, let's verify this is a valid TTY we just opened */
if (!isatty_safe(fd))
return PAM_SUCCESS;
_cleanup_free_ char *osc = NULL;
r = osc_context_close(*osc_id, &osc);
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r, "Failed to prepare OSC sequence: %m");
/* When we are closing things, the TTY might not take our writes anymore. Accept that gracefully. */
r = loop_write(fd, osc, SIZE_MAX);
if (r < 0)
pam_syslog_errno(handle, LOG_DEBUG, r, "Failed to write OSC sequence to TTY, ignoring: %m");
return PAM_SUCCESS;
}
_public_ PAM_EXTERN int pam_sm_open_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
int r;
assert(handle);
r = dlopen_libpam();
if (r < 0)
return PAM_SERVICE_ERR;
pam_log_setup();
uint64_t default_capability_bounding_set = UINT64_MAX, default_capability_ambient_set = UINT64_MAX;
const char *class_pam = NULL, *type_pam = NULL, *desktop_pam = NULL, *area_pam = NULL;
bool debug = false;
if (parse_argv(handle,
argc, argv,
&class_pam,
&type_pam,
&desktop_pam,
&area_pam,
&debug,
&default_capability_bounding_set,
&default_capability_ambient_set) < 0)
return PAM_SESSION_ERR;
pam_debug_syslog(handle, debug, "pam-systemd initializing");
_cleanup_(user_record_unrefp) UserRecord *ur = NULL;
r = acquire_user_record(handle, &ur);
if (r != PAM_SUCCESS)
return r;
SessionContext c = {};
r = pam_get_item_many(
handle,
PAM_SERVICE, &c.service,
PAM_XDISPLAY, &c.display,
PAM_TTY, &c.tty,
PAM_RUSER, &c.remote_user,
PAM_RHOST, &c.remote_host);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM items: @PAMERR@");
c.seat = getenv_harder(handle, "XDG_SEAT", NULL);
c.vtnr = getenv_harder_uint32(handle, "XDG_VTNR", 0);
c.type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
c.class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
c.desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
c.area = getenv_harder(handle, "XDG_AREA", area_pam);
c.incomplete = getenv_harder_bool(handle, "XDG_SESSION_INCOMPLETE", false);
r = pam_get_data_many(
handle,
"systemd.memory_max", &c.memory_max,
"systemd.tasks_max", &c.tasks_max,
"systemd.cpu_weight", &c.cpu_weight,
"systemd.io_weight", &c.io_weight,
"systemd.runtime_max_sec", &c.runtime_max_sec);
if (r != PAM_SUCCESS)
return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM data: @PAMERR@");
session_context_mangle(handle, &c, ur, debug);
_cleanup_free_ char *seat_buffer = NULL, *type_buffer = NULL, *runtime_dir = NULL;
r = register_session(handle, &c, ur, debug, &seat_buffer, &type_buffer, &runtime_dir);
if (r != PAM_SUCCESS)
return r;
r = import_shell_credentials(handle);
if (r != PAM_SUCCESS)
return r;
r = setup_environment(handle, ur, runtime_dir, c.area, debug);
if (r != PAM_SUCCESS)
return r;
if (default_capability_ambient_set == UINT64_MAX)
default_capability_ambient_set = pick_default_capability_ambient_set(ur, c.service, c.seat);
r = apply_user_record_settings(handle, ur, debug, default_capability_bounding_set, default_capability_ambient_set);
if (r != PAM_SUCCESS)
return r;
return open_osc_context(handle, c.type, ur);
}
_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);
pam_log_setup();
if (parse_argv(handle,
argc, argv,
/* class= */ NULL,
/* type= */ NULL,
/* desktop= */ NULL,
/* area= */ NULL,
&debug,
/* default_capability_bounding_set= */ NULL,
/* default_capability_ambient_set= */ NULL) < 0)
return PAM_SESSION_ERR;
pam_debug_syslog(handle, 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))
return pam_syslog_pam_error(handle, LOG_ERR, r,
"Failed to get PAM systemd.existing data: @PAMERR@");
(void) close_osc_context(handle);
id = pam_getenv(handle, "XDG_SESSION_ID");
if (id && !existing) {
_cleanup_(sd_varlink_unrefp) sd_varlink *vl = NULL;
bool done = false;
r = sd_varlink_connect_address(&vl, "/run/systemd/io.systemd.Login");
if (r < 0)
log_debug_errno(r, "Failed to connect to logind via Varlink, falling back to D-Bus: %m");
else {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *vreply = NULL;
const char *error_id = NULL;
r = sd_varlink_callbo(
vl,
"io.systemd.Login.ReleaseSession",
/* ret_reply= */ NULL,
&error_id,
SD_JSON_BUILD_PAIR_STRING("Id", id));
if (r < 0)
return pam_syslog_errno(handle, LOG_ERR, r,
"Failed to issue io.systemd.Login.ReleaseSession varlink call: %m");
if (error_id)
return pam_syslog_errno(handle, LOG_ERR, sd_varlink_error_to_errno(error_id, vreply),
"Varlink call io.systemd.Login.ReleaseSession failed: %s", error_id);
done = true;
}
if (!done) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(pam_bus_data_disconnectp) PamBusData *d = 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, "pam-systemd", debug, &bus, &d);
if (r != PAM_SUCCESS)
return r;
r = bus_call_method(bus, bus_login_mgr, "ReleaseSession", &error, NULL, "s", id);
if (r < 0)
return pam_syslog_pam_error(handle, LOG_ERR, PAM_SESSION_ERR,
"Failed to release session: %s", bus_error_message(&error, r));
}
}
return PAM_SUCCESS;
}
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