537 lines
17 KiB
C
537 lines
17 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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/***
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This file is part of systemd.
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Copyright 2016 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <nss.h>
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#include "sd-bus.h"
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#include "alloc-util.h"
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#include "bus-common-errors.h"
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#include "env-util.h"
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#include "fs-util.h"
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#include "macro.h"
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#include "nss-util.h"
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#include "signal-util.h"
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#include "stdio-util.h"
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#include "string-util.h"
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#include "user-util.h"
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#include "util.h"
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static const struct passwd root_passwd = {
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.pw_name = (char*) "root",
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.pw_passwd = (char*) "x", /* see shadow file */
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.pw_uid = 0,
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.pw_gid = 0,
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.pw_gecos = (char*) "Super User",
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.pw_dir = (char*) "/root",
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.pw_shell = (char*) "/bin/sh",
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};
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static const struct passwd nobody_passwd = {
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.pw_name = (char*) NOBODY_USER_NAME,
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.pw_passwd = (char*) "*", /* locked */
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.pw_uid = UID_NOBODY,
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.pw_gid = GID_NOBODY,
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.pw_gecos = (char*) "User Nobody",
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.pw_dir = (char*) "/",
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.pw_shell = (char*) "/sbin/nologin",
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};
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static const struct group root_group = {
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.gr_name = (char*) "root",
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.gr_gid = 0,
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.gr_passwd = (char*) "x", /* see shadow file */
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.gr_mem = (char*[]) { NULL },
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};
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static const struct group nobody_group = {
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.gr_name = (char*) NOBODY_GROUP_NAME,
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.gr_gid = GID_NOBODY,
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.gr_passwd = (char*) "*", /* locked */
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.gr_mem = (char*[]) { NULL },
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};
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NSS_GETPW_PROTOTYPES(systemd);
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NSS_GETGR_PROTOTYPES(systemd);
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static int direct_lookup_name(const char *name, uid_t *ret) {
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_cleanup_free_ char *s = NULL;
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const char *path;
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int r;
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assert(name);
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/* Normally, we go via the bus to resolve names. That has the benefit that it is available from any mount
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* namespace and subject to proper authentication. However, there's one problem: if our module is called from
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* dbus-daemon itself we really can't use D-Bus to communicate. In this case, resort to a client-side hack,
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* and look for the dynamic names directly. This is pretty ugly, but breaks the cyclic dependency. */
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path = strjoina("/run/systemd/dynamic-uid/direct:", name);
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r = readlink_malloc(path, &s);
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if (r < 0)
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return r;
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return parse_uid(s, ret);
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}
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static int direct_lookup_uid(uid_t uid, char **ret) {
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char path[STRLEN("/run/systemd/dynamic-uid/direct:") + DECIMAL_STR_MAX(uid_t) + 1], *s;
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int r;
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xsprintf(path, "/run/systemd/dynamic-uid/direct:" UID_FMT, uid);
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r = readlink_malloc(path, &s);
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if (r < 0)
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return r;
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if (!valid_user_group_name(s)) { /* extra safety check */
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free(s);
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return -EINVAL;
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}
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*ret = s;
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return 0;
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}
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enum nss_status _nss_systemd_getpwnam_r(
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const char *name,
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struct passwd *pwd,
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char *buffer, size_t buflen,
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int *errnop) {
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uint32_t translated;
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size_t l;
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int bypass, r;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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assert(name);
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assert(pwd);
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/* If the username is not valid, then we don't know it. Ideally libc would filter these for us anyway. We don't
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* generate EINVAL here, because it isn't really out business to complain about invalid user names. */
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if (!valid_user_group_name(name))
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goto not_found;
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/* Synthesize entries for the root and nobody users, in case they are missing in /etc/passwd */
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if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
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if (streq(name, root_passwd.pw_name)) {
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*pwd = root_passwd;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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if (streq(name, nobody_passwd.pw_name)) {
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*pwd = nobody_passwd;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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}
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/* Make sure that we don't go in circles when allocating a dynamic UID by checking our own database */
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if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
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goto not_found;
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bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
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if (bypass <= 0) {
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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r = sd_bus_open_system(&bus);
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if (r < 0) {
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bypass = 1;
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goto direct_lookup;
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}
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r = sd_bus_call_method(bus,
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"org.freedesktop.systemd1",
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"/org/freedesktop/systemd1",
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"org.freedesktop.systemd1.Manager",
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"LookupDynamicUserByName",
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&error,
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&reply,
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"s",
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name);
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if (r < 0) {
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if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
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goto not_found;
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goto fail;
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}
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r = sd_bus_message_read(reply, "u", &translated);
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if (r < 0)
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goto fail;
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}
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direct_lookup:
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if (bypass > 0) {
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/* Access the dynamic UID allocation directly if we are called from dbus-daemon, see above. */
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r = direct_lookup_name(name, (uid_t*) &translated);
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if (r == -ENOENT)
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goto not_found;
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if (r < 0)
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goto fail;
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}
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l = strlen(name);
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if (buflen < l+1) {
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*errnop = ERANGE;
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return NSS_STATUS_TRYAGAIN;
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}
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memcpy(buffer, name, l+1);
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pwd->pw_name = buffer;
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pwd->pw_uid = (uid_t) translated;
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pwd->pw_gid = (uid_t) translated;
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pwd->pw_gecos = (char*) "Dynamic User";
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pwd->pw_passwd = (char*) "*"; /* locked */
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pwd->pw_dir = (char*) "/";
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pwd->pw_shell = (char*) "/sbin/nologin";
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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not_found:
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*errnop = 0;
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return NSS_STATUS_NOTFOUND;
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fail:
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*errnop = -r;
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return NSS_STATUS_UNAVAIL;
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}
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enum nss_status _nss_systemd_getpwuid_r(
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uid_t uid,
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struct passwd *pwd,
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char *buffer, size_t buflen,
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int *errnop) {
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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_cleanup_free_ char *direct = NULL;
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const char *translated;
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size_t l;
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int bypass, r;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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if (!uid_is_valid(uid))
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goto not_found;
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/* Synthesize data for the root user and for nobody in case they are missing from /etc/passwd */
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if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
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if (uid == root_passwd.pw_uid) {
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*pwd = root_passwd;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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if (uid == nobody_passwd.pw_uid) {
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*pwd = nobody_passwd;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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}
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if (!uid_is_dynamic(uid))
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goto not_found;
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if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
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goto not_found;
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bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
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if (bypass <= 0) {
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r = sd_bus_open_system(&bus);
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if (r < 0) {
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bypass = 1;
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goto direct_lookup;
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}
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r = sd_bus_call_method(bus,
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"org.freedesktop.systemd1",
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"/org/freedesktop/systemd1",
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"org.freedesktop.systemd1.Manager",
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"LookupDynamicUserByUID",
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&error,
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&reply,
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"u",
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(uint32_t) uid);
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if (r < 0) {
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if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
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goto not_found;
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goto fail;
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}
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r = sd_bus_message_read(reply, "s", &translated);
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if (r < 0)
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goto fail;
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}
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direct_lookup:
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if (bypass > 0) {
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r = direct_lookup_uid(uid, &direct);
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if (r == -ENOENT)
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goto not_found;
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if (r < 0)
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goto fail;
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translated = direct;
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}
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l = strlen(translated) + 1;
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if (buflen < l) {
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*errnop = ERANGE;
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return NSS_STATUS_TRYAGAIN;
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}
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memcpy(buffer, translated, l);
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pwd->pw_name = buffer;
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pwd->pw_uid = uid;
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pwd->pw_gid = uid;
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pwd->pw_gecos = (char*) "Dynamic User";
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pwd->pw_passwd = (char*) "*"; /* locked */
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pwd->pw_dir = (char*) "/";
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pwd->pw_shell = (char*) "/sbin/nologin";
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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not_found:
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*errnop = 0;
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return NSS_STATUS_NOTFOUND;
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fail:
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*errnop = -r;
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return NSS_STATUS_UNAVAIL;
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}
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enum nss_status _nss_systemd_getgrnam_r(
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const char *name,
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struct group *gr,
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char *buffer, size_t buflen,
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int *errnop) {
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uint32_t translated;
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size_t l;
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int bypass, r;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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assert(name);
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assert(gr);
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if (!valid_user_group_name(name))
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goto not_found;
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/* Synthesize records for root and nobody, in case they are missing form /etc/group */
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if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
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if (streq(name, root_group.gr_name)) {
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*gr = root_group;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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if (streq(name, nobody_group.gr_name)) {
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*gr = nobody_group;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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}
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if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
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goto not_found;
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bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
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if (bypass <= 0) {
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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r = sd_bus_open_system(&bus);
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if (r < 0) {
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bypass = 1;
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goto direct_lookup;
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}
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r = sd_bus_call_method(bus,
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"org.freedesktop.systemd1",
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"/org/freedesktop/systemd1",
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"org.freedesktop.systemd1.Manager",
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"LookupDynamicUserByName",
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&error,
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&reply,
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"s",
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name);
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if (r < 0) {
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if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
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goto not_found;
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goto fail;
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}
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r = sd_bus_message_read(reply, "u", &translated);
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if (r < 0)
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goto fail;
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}
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direct_lookup:
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if (bypass > 0) {
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/* Access the dynamic GID allocation directly if we are called from dbus-daemon, see above. */
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r = direct_lookup_name(name, (uid_t*) &translated);
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if (r == -ENOENT)
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goto not_found;
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if (r < 0)
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goto fail;
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}
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l = sizeof(char*) + strlen(name) + 1;
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if (buflen < l) {
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*errnop = ERANGE;
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return NSS_STATUS_TRYAGAIN;
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}
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memzero(buffer, sizeof(char*));
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strcpy(buffer + sizeof(char*), name);
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gr->gr_name = buffer + sizeof(char*);
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gr->gr_gid = (gid_t) translated;
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gr->gr_passwd = (char*) "*"; /* locked */
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gr->gr_mem = (char**) buffer;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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not_found:
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*errnop = 0;
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return NSS_STATUS_NOTFOUND;
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fail:
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*errnop = -r;
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return NSS_STATUS_UNAVAIL;
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}
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enum nss_status _nss_systemd_getgrgid_r(
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gid_t gid,
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struct group *gr,
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char *buffer, size_t buflen,
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int *errnop) {
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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_cleanup_free_ char *direct = NULL;
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const char *translated;
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size_t l;
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int bypass, r;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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if (!gid_is_valid(gid))
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goto not_found;
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/* Synthesize records for root and nobody, in case they are missing from /etc/group */
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if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
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if (gid == root_group.gr_gid) {
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*gr = root_group;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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if (gid == nobody_group.gr_gid) {
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*gr = nobody_group;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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}
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}
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if (!gid_is_dynamic(gid))
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goto not_found;
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if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
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goto not_found;
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bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
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if (bypass <= 0) {
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r = sd_bus_open_system(&bus);
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if (r < 0) {
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bypass = 1;
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goto direct_lookup;
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}
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r = sd_bus_call_method(bus,
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"org.freedesktop.systemd1",
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"/org/freedesktop/systemd1",
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"org.freedesktop.systemd1.Manager",
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"LookupDynamicUserByUID",
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&error,
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&reply,
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"u",
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(uint32_t) gid);
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if (r < 0) {
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if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
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goto not_found;
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goto fail;
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}
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r = sd_bus_message_read(reply, "s", &translated);
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if (r < 0)
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goto fail;
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}
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direct_lookup:
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if (bypass > 0) {
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r = direct_lookup_uid(gid, &direct);
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if (r == -ENOENT)
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goto not_found;
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if (r < 0)
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goto fail;
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translated = direct;
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}
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l = sizeof(char*) + strlen(translated) + 1;
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if (buflen < l) {
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*errnop = ERANGE;
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return NSS_STATUS_TRYAGAIN;
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}
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memzero(buffer, sizeof(char*));
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strcpy(buffer + sizeof(char*), translated);
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gr->gr_name = buffer + sizeof(char*);
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gr->gr_gid = gid;
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gr->gr_passwd = (char*) "*"; /* locked */
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gr->gr_mem = (char**) buffer;
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*errnop = 0;
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return NSS_STATUS_SUCCESS;
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not_found:
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*errnop = 0;
|
|
return NSS_STATUS_NOTFOUND;
|
|
|
|
fail:
|
|
*errnop = -r;
|
|
return NSS_STATUS_UNAVAIL;
|
|
}
|