]> git.ipfire.org Git - thirdparty/systemd.git/blobdiff - src/nss-systemd/nss-systemd.c
Merge pull request #11827 from keszybz/pkgconfig-variables
[thirdparty/systemd.git] / src / nss-systemd / nss-systemd.c
index cc641e16154f461eaa90590e15505f32d443d3fd..f8db27ae2766d605cb0e535ad10736b67ef71d8b 100644 (file)
@@ -1,31 +1,17 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
-/***
-  This file is part of systemd.
-
-  Copyright 2016 Lennart Poettering
-
-  systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU Lesser General Public License as published by
-  the Free Software Foundation; either version 2.1 of the License, or
-  (at your option) any later version.
-
-  systemd is distributed in the hope that it will be useful, but
-  WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
 
 #include <nss.h>
+#include <pthread.h>
 
 #include "sd-bus.h"
 
 #include "alloc-util.h"
 #include "bus-common-errors.h"
+#include "dirent-util.h"
 #include "env-util.h"
+#include "fd-util.h"
 #include "fs-util.h"
+#include "list.h"
 #include "macro.h"
 #include "nss-util.h"
 #include "signal-util.h"
 #include "user-util.h"
 #include "util.h"
 
+#define DYNAMIC_USER_GECOS       "Dynamic User"
+#define DYNAMIC_USER_PASSWD      "*" /* locked */
+#define DYNAMIC_USER_DIR         "/"
+#define DYNAMIC_USER_SHELL       "/sbin/nologin"
+
 static const struct passwd root_passwd = {
         .pw_name = (char*) "root",
         .pw_passwd = (char*) "x", /* see shadow file */
@@ -68,8 +59,40 @@ static const struct group nobody_group = {
         .gr_mem = (char*[]) { NULL },
 };
 
+typedef struct UserEntry UserEntry;
+typedef struct GetentData GetentData;
+
+struct UserEntry {
+        uid_t id;
+        char *name;
+
+        GetentData *data;
+        LIST_FIELDS(UserEntry, entries);
+};
+
+struct GetentData {
+        /* As explained in NOTES section of getpwent_r(3) as 'getpwent_r() is not really
+         * reentrant since it shares the reading position in the stream with all other threads',
+         * we need to protect the data in UserEntry from multithreaded programs which may call
+         * setpwent(), getpwent_r(), or endpwent() simultaneously. So, each function locks the
+         * data by using the mutex below. */
+        pthread_mutex_t mutex;
+
+        UserEntry *position;
+        LIST_HEAD(UserEntry, entries);
+};
+
+static GetentData getpwent_data = { PTHREAD_MUTEX_INITIALIZER, NULL, NULL };
+static GetentData getgrent_data = { PTHREAD_MUTEX_INITIALIZER, NULL, NULL };
+
 NSS_GETPW_PROTOTYPES(systemd);
 NSS_GETGR_PROTOTYPES(systemd);
+enum nss_status _nss_systemd_endpwent(void) _public_;
+enum nss_status _nss_systemd_setpwent(int stayopen) _public_;
+enum nss_status _nss_systemd_getpwent_r(struct passwd *result, char *buffer, size_t buflen, int *errnop) _public_;
+enum nss_status _nss_systemd_endgrent(void) _public_;
+enum nss_status _nss_systemd_setgrent(int stayopen) _public_;
+enum nss_status _nss_systemd_getgrent_r(struct group *result, char *buffer, size_t buflen, int *errnop) _public_;
 
 static int direct_lookup_name(const char *name, uid_t *ret) {
         _cleanup_free_ char *s = NULL;
@@ -115,10 +138,14 @@ enum nss_status _nss_systemd_getpwnam_r(
                 char *buffer, size_t buflen,
                 int *errnop) {
 
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
         uint32_t translated;
         size_t l;
         int bypass, r;
 
+        PROTECT_ERRNO;
         BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
 
         assert(name);
@@ -127,38 +154,39 @@ enum nss_status _nss_systemd_getpwnam_r(
         /* If the username is not valid, then we don't know it. Ideally libc would filter these for us anyway. We don't
          * generate EINVAL here, because it isn't really out business to complain about invalid user names. */
         if (!valid_user_group_name(name))
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         /* Synthesize entries for the root and nobody users, in case they are missing in /etc/passwd */
         if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
                 if (streq(name, root_passwd.pw_name)) {
                         *pwd = root_passwd;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
-                if (streq(name, nobody_passwd.pw_name)) {
+                if (synthesize_nobody() &&
+                    streq(name, nobody_passwd.pw_name)) {
                         *pwd = nobody_passwd;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
         }
 
         /* Make sure that we don't go in circles when allocating a dynamic UID by checking our own database */
         if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
         if (bypass <= 0) {
-                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
-                _cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
-                _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
-
                 r = sd_bus_open_system(&bus);
-                if (r < 0) {
+                if (r < 0)
                         bypass = 1;
-                        goto direct_lookup;
-                }
+        }
 
+        if (bypass > 0) {
+                r = direct_lookup_name(name, (uid_t*) &translated);
+                if (r == -ENOENT)
+                        return NSS_STATUS_NOTFOUND;
+                if (r < 0)
+                        goto fail;
+        } else {
                 r = sd_bus_call_method(bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
@@ -170,7 +198,7 @@ enum nss_status _nss_systemd_getpwnam_r(
                                        name);
                 if (r < 0) {
                         if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
-                                goto not_found;
+                                return NSS_STATUS_NOTFOUND;
 
                         goto fail;
                 }
@@ -180,18 +208,9 @@ enum nss_status _nss_systemd_getpwnam_r(
                         goto fail;
         }
 
-direct_lookup:
-        if (bypass > 0) {
-                /* Access the dynamic UID allocation directly if we are called from dbus-daemon, see above. */
-                r = direct_lookup_name(name, (uid_t*) &translated);
-                if (r == -ENOENT)
-                        goto not_found;
-                if (r < 0)
-                        goto fail;
-        }
-
         l = strlen(name);
         if (buflen < l+1) {
+                UNPROTECT_ERRNO;
                 *errnop = ERANGE;
                 return NSS_STATUS_TRYAGAIN;
         }
@@ -201,19 +220,15 @@ direct_lookup:
         pwd->pw_name = buffer;
         pwd->pw_uid = (uid_t) translated;
         pwd->pw_gid = (uid_t) translated;
-        pwd->pw_gecos = (char*) "Dynamic User";
-        pwd->pw_passwd = (char*) "*"; /* locked */
-        pwd->pw_dir = (char*) "/";
-        pwd->pw_shell = (char*) "/sbin/nologin";
+        pwd->pw_gecos = (char*) DYNAMIC_USER_GECOS;
+        pwd->pw_passwd = (char*) DYNAMIC_USER_PASSWD;
+        pwd->pw_dir = (char*) DYNAMIC_USER_DIR;
+        pwd->pw_shell = (char*) DYNAMIC_USER_SHELL;
 
-        *errnop = 0;
         return NSS_STATUS_SUCCESS;
 
-not_found:
-        *errnop = 0;
-        return NSS_STATUS_NOTFOUND;
-
 fail:
+        UNPROTECT_ERRNO;
         *errnop = -r;
         return NSS_STATUS_UNAVAIL;
 }
@@ -232,39 +247,48 @@ enum nss_status _nss_systemd_getpwuid_r(
         size_t l;
         int bypass, r;
 
+        PROTECT_ERRNO;
         BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
 
         if (!uid_is_valid(uid))
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         /* Synthesize data for the root user and for nobody in case they are missing from /etc/passwd */
         if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
                 if (uid == root_passwd.pw_uid) {
                         *pwd = root_passwd;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
-                if (uid == nobody_passwd.pw_uid) {
+                if (synthesize_nobody() &&
+                    uid == nobody_passwd.pw_uid) {
                         *pwd = nobody_passwd;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
         }
 
         if (!uid_is_dynamic(uid))
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
         if (bypass <= 0) {
                 r = sd_bus_open_system(&bus);
-                if (r < 0) {
+                if (r < 0)
                         bypass = 1;
-                        goto direct_lookup;
-                }
+        }
+
+        if (bypass > 0) {
+                r = direct_lookup_uid(uid, &direct);
+                if (r == -ENOENT)
+                        return NSS_STATUS_NOTFOUND;
+                if (r < 0)
+                        goto fail;
 
+                translated = direct;
+
+        } else {
                 r = sd_bus_call_method(bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
@@ -276,7 +300,7 @@ enum nss_status _nss_systemd_getpwuid_r(
                                        (uint32_t) uid);
                 if (r < 0) {
                         if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
-                                goto not_found;
+                                return NSS_STATUS_NOTFOUND;
 
                         goto fail;
                 }
@@ -286,20 +310,9 @@ enum nss_status _nss_systemd_getpwuid_r(
                         goto fail;
         }
 
-direct_lookup:
-        if (bypass > 0) {
-                r = direct_lookup_uid(uid, &direct);
-                if (r == -ENOENT)
-                        goto not_found;
-                if (r < 0)
-                        goto fail;
-
-                translated = direct;
-
-        }
-
         l = strlen(translated) + 1;
         if (buflen < l) {
+                UNPROTECT_ERRNO;
                 *errnop = ERANGE;
                 return NSS_STATUS_TRYAGAIN;
         }
@@ -309,70 +322,73 @@ direct_lookup:
         pwd->pw_name = buffer;
         pwd->pw_uid = uid;
         pwd->pw_gid = uid;
-        pwd->pw_gecos = (char*) "Dynamic User";
-        pwd->pw_passwd = (char*) "*"; /* locked */
-        pwd->pw_dir = (char*) "/";
-        pwd->pw_shell = (char*) "/sbin/nologin";
+        pwd->pw_gecos = (char*) DYNAMIC_USER_GECOS;
+        pwd->pw_passwd = (char*) DYNAMIC_USER_PASSWD;
+        pwd->pw_dir = (char*) DYNAMIC_USER_DIR;
+        pwd->pw_shell = (char*) DYNAMIC_USER_SHELL;
 
-        *errnop = 0;
         return NSS_STATUS_SUCCESS;
 
-not_found:
-        *errnop = 0;
-        return NSS_STATUS_NOTFOUND;
-
 fail:
+        UNPROTECT_ERRNO;
         *errnop = -r;
         return NSS_STATUS_UNAVAIL;
 }
 
+#pragma GCC diagnostic ignored "-Wsizeof-pointer-memaccess"
+
 enum nss_status _nss_systemd_getgrnam_r(
                 const char *name,
                 struct group *gr,
                 char *buffer, size_t buflen,
                 int *errnop) {
 
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
         uint32_t translated;
         size_t l;
         int bypass, r;
 
+        PROTECT_ERRNO;
         BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
 
         assert(name);
         assert(gr);
 
         if (!valid_user_group_name(name))
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         /* Synthesize records for root and nobody, in case they are missing form /etc/group */
         if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
                 if (streq(name, root_group.gr_name)) {
                         *gr = root_group;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
-                if (streq(name, nobody_group.gr_name)) {
+                if (synthesize_nobody() &&
+                    streq(name, nobody_group.gr_name)) {
                         *gr = nobody_group;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
         }
 
         if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
         if (bypass <= 0) {
-                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
-                _cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
-                _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
-
                 r = sd_bus_open_system(&bus);
-                if (r < 0) {
+                if (r < 0)
                         bypass = 1;
-                        goto direct_lookup;
-                }
+        }
 
+        if (bypass > 0) {
+                r = direct_lookup_name(name, (uid_t*) &translated);
+                if (r == -ENOENT)
+                        return NSS_STATUS_NOTFOUND;
+                if (r < 0)
+                        goto fail;
+        } else {
                 r = sd_bus_call_method(bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
@@ -384,7 +400,7 @@ enum nss_status _nss_systemd_getgrnam_r(
                                        name);
                 if (r < 0) {
                         if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
-                                goto not_found;
+                                return NSS_STATUS_NOTFOUND;
 
                         goto fail;
                 }
@@ -394,18 +410,9 @@ enum nss_status _nss_systemd_getgrnam_r(
                         goto fail;
         }
 
-direct_lookup:
-        if (bypass > 0) {
-                /* Access the dynamic GID allocation directly if we are called from dbus-daemon, see above. */
-                r = direct_lookup_name(name, (uid_t*) &translated);
-                if (r == -ENOENT)
-                        goto not_found;
-                if (r < 0)
-                        goto fail;
-        }
-
         l = sizeof(char*) + strlen(name) + 1;
         if (buflen < l) {
+                UNPROTECT_ERRNO;
                 *errnop = ERANGE;
                 return NSS_STATUS_TRYAGAIN;
         }
@@ -415,17 +422,13 @@ direct_lookup:
 
         gr->gr_name = buffer + sizeof(char*);
         gr->gr_gid = (gid_t) translated;
-        gr->gr_passwd = (char*) "*"; /* locked */
+        gr->gr_passwd = (char*) DYNAMIC_USER_PASSWD;
         gr->gr_mem = (char**) buffer;
 
-        *errnop = 0;
         return NSS_STATUS_SUCCESS;
 
-not_found:
-        *errnop = 0;
-        return NSS_STATUS_NOTFOUND;
-
 fail:
+        UNPROTECT_ERRNO;
         *errnop = -r;
         return NSS_STATUS_UNAVAIL;
 }
@@ -444,39 +447,48 @@ enum nss_status _nss_systemd_getgrgid_r(
         size_t l;
         int bypass, r;
 
+        PROTECT_ERRNO;
         BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
 
         if (!gid_is_valid(gid))
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         /* Synthesize records for root and nobody, in case they are missing from /etc/group */
         if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) {
                 if (gid == root_group.gr_gid) {
                         *gr = root_group;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
-                if (gid == nobody_group.gr_gid) {
+                if (synthesize_nobody() &&
+                    gid == nobody_group.gr_gid) {
                         *gr = nobody_group;
-                        *errnop = 0;
                         return NSS_STATUS_SUCCESS;
                 }
         }
 
         if (!gid_is_dynamic(gid))
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
-                goto not_found;
+                return NSS_STATUS_NOTFOUND;
 
         bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
         if (bypass <= 0) {
                 r = sd_bus_open_system(&bus);
-                if (r < 0) {
+                if (r < 0)
                         bypass = 1;
-                        goto direct_lookup;
-                }
+        }
+
+        if (bypass > 0) {
+                r = direct_lookup_uid(gid, &direct);
+                if (r == -ENOENT)
+                        return NSS_STATUS_NOTFOUND;
+                if (r < 0)
+                        goto fail;
+
+                translated = direct;
 
+        } else {
                 r = sd_bus_call_method(bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
@@ -488,7 +500,7 @@ enum nss_status _nss_systemd_getgrgid_r(
                                        (uint32_t) gid);
                 if (r < 0) {
                         if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
-                                goto not_found;
+                                return NSS_STATUS_NOTFOUND;
 
                         goto fail;
                 }
@@ -498,19 +510,9 @@ enum nss_status _nss_systemd_getgrgid_r(
                         goto fail;
         }
 
-direct_lookup:
-        if (bypass > 0) {
-                r = direct_lookup_uid(gid, &direct);
-                if (r == -ENOENT)
-                        goto not_found;
-                if (r < 0)
-                        goto fail;
-
-                translated = direct;
-        }
-
         l = sizeof(char*) + strlen(translated) + 1;
         if (buflen < l) {
+                UNPROTECT_ERRNO;
                 *errnop = ERANGE;
                 return NSS_STATUS_TRYAGAIN;
         }
@@ -520,17 +522,313 @@ direct_lookup:
 
         gr->gr_name = buffer + sizeof(char*);
         gr->gr_gid = gid;
-        gr->gr_passwd = (char*) "*"; /* locked */
+        gr->gr_passwd = (char*) DYNAMIC_USER_PASSWD;
         gr->gr_mem = (char**) buffer;
 
-        *errnop = 0;
         return NSS_STATUS_SUCCESS;
 
-not_found:
-        *errnop = 0;
-        return NSS_STATUS_NOTFOUND;
-
 fail:
+        UNPROTECT_ERRNO;
         *errnop = -r;
         return NSS_STATUS_UNAVAIL;
 }
+
+static void user_entry_free(UserEntry *p) {
+        if (!p)
+                return;
+
+        if (p->data)
+                LIST_REMOVE(entries, p->data->entries, p);
+
+        free(p->name);
+        free(p);
+}
+
+static int user_entry_add(GetentData *data, const char *name, uid_t id) {
+        UserEntry *p;
+
+        assert(data);
+
+        /* This happens when User= or Group= already exists statically. */
+        if (!uid_is_dynamic(id))
+                return -EINVAL;
+
+        p = new0(UserEntry, 1);
+        if (!p)
+                return -ENOMEM;
+
+        p->name = strdup(name);
+        if (!p->name) {
+                free(p);
+                return -ENOMEM;
+        }
+        p->id = id;
+        p->data = data;
+
+        LIST_PREPEND(entries, data->entries, p);
+
+        return 0;
+}
+
+static void systemd_endent(GetentData *data) {
+        UserEntry *p;
+
+        assert(data);
+
+        while ((p = data->entries))
+                user_entry_free(p);
+
+        data->position = NULL;
+}
+
+static enum nss_status nss_systemd_endent(GetentData *p) {
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert_se(pthread_mutex_lock(&p->mutex) == 0);
+        systemd_endent(p);
+        assert_se(pthread_mutex_unlock(&p->mutex) == 0);
+
+        return NSS_STATUS_SUCCESS;
+}
+
+enum nss_status _nss_systemd_endpwent(void) {
+        return nss_systemd_endent(&getpwent_data);
+}
+
+enum nss_status _nss_systemd_endgrent(void) {
+        return nss_systemd_endent(&getgrent_data);
+}
+
+static int direct_enumeration(GetentData *p) {
+        _cleanup_closedir_ DIR *d = NULL;
+        struct dirent *de;
+        int r;
+
+        assert(p);
+
+        d = opendir("/run/systemd/dynamic-uid/");
+        if (!d)
+                return -errno;
+
+        FOREACH_DIRENT(de, d, return -errno) {
+                _cleanup_free_ char *name = NULL;
+                uid_t uid, verified;
+
+                if (!dirent_is_file(de))
+                        continue;
+
+                r = parse_uid(de->d_name, &uid);
+                if (r < 0)
+                        continue;
+
+                r = direct_lookup_uid(uid, &name);
+                if (r == -ENOMEM)
+                        return r;
+                if (r < 0)
+                        continue;
+
+                r = direct_lookup_name(name, &verified);
+                if (r < 0)
+                        continue;
+
+                if (uid != verified)
+                        continue;
+
+                r = user_entry_add(p, name, uid);
+                if (r == -ENOMEM)
+                        return r;
+                if (r < 0)
+                        continue;
+        }
+
+        return 0;
+}
+
+static enum nss_status systemd_setent(GetentData *p) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
+        const char *name;
+        uid_t id;
+        int bypass, r;
+
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert(p);
+
+        assert_se(pthread_mutex_lock(&p->mutex) == 0);
+
+        systemd_endent(p);
+
+        if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
+                goto finish;
+
+        bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
+
+        if (bypass <= 0) {
+                r = sd_bus_open_system(&bus);
+                if (r < 0)
+                        bypass = 1;
+        }
+
+        if (bypass > 0) {
+                r = direct_enumeration(p);
+                if (r < 0)
+                        goto fail;
+
+                goto finish;
+        }
+
+        r = sd_bus_call_method(bus,
+                               "org.freedesktop.systemd1",
+                               "/org/freedesktop/systemd1",
+                               "org.freedesktop.systemd1.Manager",
+                               "GetDynamicUsers",
+                               &error,
+                               &reply,
+                               NULL);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_enter_container(reply, 'a', "(us)");
+        if (r < 0)
+                goto fail;
+
+        while ((r = sd_bus_message_read(reply, "(us)", &id, &name)) > 0) {
+                r = user_entry_add(p, name, id);
+                if (r == -ENOMEM)
+                        goto fail;
+                if (r < 0)
+                        continue;
+        }
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_exit_container(reply);
+        if (r < 0)
+                goto fail;
+
+finish:
+        p->position = p->entries;
+        assert_se(pthread_mutex_unlock(&p->mutex) == 0);
+
+        return NSS_STATUS_SUCCESS;
+
+fail:
+        systemd_endent(p);
+        assert_se(pthread_mutex_unlock(&p->mutex) == 0);
+
+        return NSS_STATUS_UNAVAIL;
+}
+
+enum nss_status _nss_systemd_setpwent(int stayopen) {
+        return systemd_setent(&getpwent_data);
+}
+
+enum nss_status _nss_systemd_setgrent(int stayopen) {
+        return systemd_setent(&getgrent_data);
+}
+
+enum nss_status _nss_systemd_getpwent_r(struct passwd *result, char *buffer, size_t buflen, int *errnop) {
+        enum nss_status ret;
+        UserEntry *p;
+        size_t len;
+
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert(result);
+        assert(buffer);
+        assert(errnop);
+
+        assert_se(pthread_mutex_lock(&getpwent_data.mutex) == 0);
+
+        LIST_FOREACH(entries, p, getpwent_data.position) {
+                len = strlen(p->name) + 1;
+                if (buflen < len) {
+                        UNPROTECT_ERRNO;
+                        *errnop = ERANGE;
+                        ret = NSS_STATUS_TRYAGAIN;
+                        goto finalize;
+                }
+
+                memcpy(buffer, p->name, len);
+
+                result->pw_name = buffer;
+                result->pw_uid = p->id;
+                result->pw_gid = p->id;
+                result->pw_gecos = (char*) DYNAMIC_USER_GECOS;
+                result->pw_passwd = (char*) DYNAMIC_USER_PASSWD;
+                result->pw_dir = (char*) DYNAMIC_USER_DIR;
+                result->pw_shell = (char*) DYNAMIC_USER_SHELL;
+                break;
+        }
+        if (!p) {
+                ret = NSS_STATUS_NOTFOUND;
+                goto finalize;
+        }
+
+        /* On success, step to the next entry. */
+        p = p->entries_next;
+        ret = NSS_STATUS_SUCCESS;
+
+finalize:
+        /* Save position for the next call. */
+        getpwent_data.position = p;
+
+        assert_se(pthread_mutex_unlock(&getpwent_data.mutex) == 0);
+
+        return ret;
+}
+
+enum nss_status _nss_systemd_getgrent_r(struct group *result, char *buffer, size_t buflen, int *errnop) {
+        enum nss_status ret;
+        UserEntry *p;
+        size_t len;
+
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert(result);
+        assert(buffer);
+        assert(errnop);
+
+        assert_se(pthread_mutex_lock(&getgrent_data.mutex) == 0);
+
+        LIST_FOREACH(entries, p, getgrent_data.position) {
+                len = sizeof(char*) + strlen(p->name) + 1;
+                if (buflen < len) {
+                        UNPROTECT_ERRNO;
+                        *errnop = ERANGE;
+                        ret = NSS_STATUS_TRYAGAIN;
+                        goto finalize;
+                }
+
+                memzero(buffer, sizeof(char*));
+                strcpy(buffer + sizeof(char*), p->name);
+
+                result->gr_name = buffer + sizeof(char*);
+                result->gr_gid = p->id;
+                result->gr_passwd = (char*) DYNAMIC_USER_PASSWD;
+                result->gr_mem = (char**) buffer;
+                break;
+        }
+        if (!p) {
+                ret = NSS_STATUS_NOTFOUND;
+                goto finalize;
+        }
+
+        /* On success, step to the next entry. */
+        p = p->entries_next;
+        ret = NSS_STATUS_SUCCESS;
+
+finalize:
+        /* Save position for the next call. */
+        getgrent_data.position = p;
+
+        assert_se(pthread_mutex_unlock(&getgrent_data.mutex) == 0);
+
+        return ret;
+}