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Diffstat (limited to 'src/nss-systemd/nss-systemd.c')
-rw-r--r--src/nss-systemd/nss-systemd.c523
1 files changed, 523 insertions, 0 deletions
diff --git a/src/nss-systemd/nss-systemd.c b/src/nss-systemd/nss-systemd.c
new file mode 100644
index 0000000000..17d04e958d
--- /dev/null
+++ b/src/nss-systemd/nss-systemd.c
@@ -0,0 +1,523 @@
+/***
+ 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 "sd-bus.h"
+
+#include "alloc-util.h"
+#include "bus-common-errors.h"
+#include "env-util.h"
+#include "fs-util.h"
+#include "macro.h"
+#include "nss-util.h"
+#include "signal-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "user-util.h"
+#include "util.h"
+
+#ifndef NOBODY_USER_NAME
+#define NOBODY_USER_NAME "nobody"
+#endif
+
+#ifndef NOBODY_GROUP_NAME
+#define NOBODY_GROUP_NAME "nobody"
+#endif
+
+static const struct passwd root_passwd = {
+ .pw_name = (char*) "root",
+ .pw_passwd = (char*) "x", /* see shadow file */
+ .pw_uid = 0,
+ .pw_gid = 0,
+ .pw_gecos = (char*) "Super User",
+ .pw_dir = (char*) "/root",
+ .pw_shell = (char*) "/bin/sh",
+};
+
+static const struct passwd nobody_passwd = {
+ .pw_name = (char*) NOBODY_USER_NAME,
+ .pw_passwd = (char*) "*", /* locked */
+ .pw_uid = 65534,
+ .pw_gid = 65534,
+ .pw_gecos = (char*) "User Nobody",
+ .pw_dir = (char*) "/",
+ .pw_shell = (char*) "/sbin/nologin",
+};
+
+static const struct group root_group = {
+ .gr_name = (char*) "root",
+ .gr_gid = 0,
+ .gr_passwd = (char*) "x", /* see shadow file */
+ .gr_mem = (char*[]) { NULL },
+};
+
+static const struct group nobody_group = {
+ .gr_name = (char*) NOBODY_GROUP_NAME,
+ .gr_gid = 65534,
+ .gr_passwd = (char*) "*", /* locked */
+ .gr_mem = (char*[]) { NULL },
+};
+
+NSS_GETPW_PROTOTYPES(systemd);
+NSS_GETGR_PROTOTYPES(systemd);
+
+static int direct_lookup_name(const char *name, uid_t *ret) {
+ _cleanup_free_ char *s = NULL;
+ const char *path;
+ int r;
+
+ assert(name);
+
+ /* Normally, we go via the bus to resolve names. That has the benefit that it is available from any mount
+ * namespace and subject to proper authentication. However, there's one problem: if our module is called from
+ * dbus-daemon itself we really can't use D-Bus to communicate. In this case, resort to a client-side hack,
+ * and look for the dynamic names directly. This is pretty ugly, but breaks the cyclic dependency. */
+
+ path = strjoina("/run/systemd/dynamic-uid/direct:", name);
+ r = readlink_malloc(path, &s);
+ if (r < 0)
+ return r;
+
+ return parse_uid(s, ret);
+}
+
+static int direct_lookup_uid(uid_t uid, char **ret) {
+ char path[strlen("/run/systemd/dynamic-uid/direct:") + DECIMAL_STR_MAX(uid_t) + 1], *s;
+ int r;
+
+ xsprintf(path, "/run/systemd/dynamic-uid/direct:" UID_FMT, uid);
+
+ r = readlink_malloc(path, &s);
+ if (r < 0)
+ return r;
+ if (!valid_user_group_name(s)) { /* extra safety check */
+ free(s);
+ return -EINVAL;
+ }
+
+ *ret = s;
+ return 0;
+}
+
+enum nss_status _nss_systemd_getpwnam_r(
+ const char *name,
+ struct passwd *pwd,
+ char *buffer, size_t buflen,
+ int *errnop) {
+
+ uint32_t translated;
+ size_t l;
+ int r;
+
+ BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+ assert(name);
+ assert(pwd);
+
+ if (!valid_user_group_name(name)) {
+ r = -EINVAL;
+ goto fail;
+ }
+
+ /* Synthesize entries for the root and nobody users, in case they are missing in /etc/passwd */
+ if (streq(name, root_passwd.pw_name)) {
+ *pwd = root_passwd;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+ if (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("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
+ goto not_found;
+
+ if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 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;
+
+ } else {
+ _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)
+ goto fail;
+
+ r = sd_bus_call_method(bus,
+ "org.freedesktop.systemd1",
+ "/org/freedesktop/systemd1",
+ "org.freedesktop.systemd1.Manager",
+ "LookupDynamicUserByName",
+ &error,
+ &reply,
+ "s",
+ name);
+ if (r < 0) {
+ if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
+ goto not_found;
+
+ goto fail;
+ }
+
+ r = sd_bus_message_read(reply, "u", &translated);
+ if (r < 0)
+ goto fail;
+ }
+
+ l = strlen(name);
+ if (buflen < l+1) {
+ *errnop = ENOMEM;
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ memcpy(buffer, name, l+1);
+
+ 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";
+
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+
+not_found:
+ *errnop = 0;
+ return NSS_STATUS_NOTFOUND;
+
+fail:
+ *errnop = -r;
+ return NSS_STATUS_UNAVAIL;
+}
+
+enum nss_status _nss_systemd_getpwuid_r(
+ uid_t uid,
+ struct passwd *pwd,
+ 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;
+ _cleanup_free_ char *direct = NULL;
+ const char *translated;
+ size_t l;
+ int r;
+
+ BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+ if (!uid_is_valid(uid)) {
+ r = -EINVAL;
+ goto fail;
+ }
+
+ /* Synthesize data for the root user and for nobody in case they are missing from /etc/passwd */
+ if (uid == root_passwd.pw_uid) {
+ *pwd = root_passwd;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+ if (uid == nobody_passwd.pw_uid) {
+ *pwd = nobody_passwd;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+
+ if (uid <= SYSTEM_UID_MAX)
+ goto not_found;
+
+ if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
+ goto not_found;
+
+ if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 0) {
+
+ r = direct_lookup_uid(uid, &direct);
+ if (r == -ENOENT)
+ goto not_found;
+ if (r < 0)
+ goto fail;
+
+ translated = direct;
+
+ } else {
+ r = sd_bus_open_system(&bus);
+ if (r < 0)
+ goto fail;
+
+ r = sd_bus_call_method(bus,
+ "org.freedesktop.systemd1",
+ "/org/freedesktop/systemd1",
+ "org.freedesktop.systemd1.Manager",
+ "LookupDynamicUserByUID",
+ &error,
+ &reply,
+ "u",
+ (uint32_t) uid);
+ if (r < 0) {
+ if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
+ goto not_found;
+
+ goto fail;
+ }
+
+ r = sd_bus_message_read(reply, "s", &translated);
+ if (r < 0)
+ goto fail;
+ }
+
+ l = strlen(translated) + 1;
+ if (buflen < l) {
+ *errnop = ENOMEM;
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ memcpy(buffer, translated, l);
+
+ 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";
+
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+
+not_found:
+ *errnop = 0;
+ return NSS_STATUS_NOTFOUND;
+
+fail:
+ *errnop = -r;
+ return NSS_STATUS_UNAVAIL;
+}
+
+enum nss_status _nss_systemd_getgrnam_r(
+ const char *name,
+ struct group *gr,
+ char *buffer, size_t buflen,
+ int *errnop) {
+
+ uint32_t translated;
+ size_t l;
+ int r;
+
+ BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+ assert(name);
+ assert(gr);
+
+ if (!valid_user_group_name(name)) {
+ r = -EINVAL;
+ goto fail;
+ }
+
+ /* Synthesize records for root and nobody, in case they are missing form /etc/group */
+ if (streq(name, root_group.gr_name)) {
+ *gr = root_group;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+ if (streq(name, nobody_group.gr_name)) {
+ *gr = nobody_group;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+
+ if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
+ goto not_found;
+
+ if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 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;
+ } else {
+
+ _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)
+ goto fail;
+
+ r = sd_bus_call_method(bus,
+ "org.freedesktop.systemd1",
+ "/org/freedesktop/systemd1",
+ "org.freedesktop.systemd1.Manager",
+ "LookupDynamicUserByName",
+ &error,
+ &reply,
+ "s",
+ name);
+ if (r < 0) {
+ if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
+ goto not_found;
+
+ goto fail;
+ }
+
+ r = sd_bus_message_read(reply, "u", &translated);
+ if (r < 0)
+ goto fail;
+ }
+
+ l = sizeof(char*) + strlen(name) + 1;
+ if (buflen < l) {
+ *errnop = ENOMEM;
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ memzero(buffer, sizeof(char*));
+ strcpy(buffer + sizeof(char*), name);
+
+ gr->gr_name = buffer + sizeof(char*);
+ gr->gr_gid = (gid_t) translated;
+ gr->gr_passwd = (char*) "*"; /* locked */
+ gr->gr_mem = (char**) buffer;
+
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+
+not_found:
+ *errnop = 0;
+ return NSS_STATUS_NOTFOUND;
+
+fail:
+ *errnop = -r;
+ return NSS_STATUS_UNAVAIL;
+}
+
+enum nss_status _nss_systemd_getgrgid_r(
+ gid_t gid,
+ 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;
+ _cleanup_free_ char *direct = NULL;
+ const char *translated;
+ size_t l;
+ int r;
+
+ BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+ if (!gid_is_valid(gid)) {
+ r = -EINVAL;
+ goto fail;
+ }
+
+ /* Synthesize records for root and nobody, in case they are missing from /etc/group */
+ if (gid == root_group.gr_gid) {
+ *gr = root_group;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+ if (gid == nobody_group.gr_gid) {
+ *gr = nobody_group;
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+ }
+
+ if (gid <= SYSTEM_GID_MAX)
+ goto not_found;
+
+ if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
+ goto not_found;
+
+ if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 0) {
+
+ r = direct_lookup_uid(gid, &direct);
+ if (r == -ENOENT)
+ goto not_found;
+ if (r < 0)
+ goto fail;
+
+ translated = direct;
+ } else {
+ r = sd_bus_open_system(&bus);
+ if (r < 0)
+ goto fail;
+
+ r = sd_bus_call_method(bus,
+ "org.freedesktop.systemd1",
+ "/org/freedesktop/systemd1",
+ "org.freedesktop.systemd1.Manager",
+ "LookupDynamicUserByUID",
+ &error,
+ &reply,
+ "u",
+ (uint32_t) gid);
+ if (r < 0) {
+ if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER))
+ goto not_found;
+
+ goto fail;
+ }
+
+ r = sd_bus_message_read(reply, "s", &translated);
+ if (r < 0)
+ goto fail;
+ }
+
+ l = sizeof(char*) + strlen(translated) + 1;
+ if (buflen < l) {
+ *errnop = ENOMEM;
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ memzero(buffer, sizeof(char*));
+ strcpy(buffer + sizeof(char*), translated);
+
+ gr->gr_name = buffer + sizeof(char*);
+ gr->gr_gid = gid;
+ gr->gr_passwd = (char*) "*"; /* locked */
+ gr->gr_mem = (char**) buffer;
+
+ *errnop = 0;
+ return NSS_STATUS_SUCCESS;
+
+not_found:
+ *errnop = 0;
+ return NSS_STATUS_NOTFOUND;
+
+fail:
+ *errnop = -r;
+ return NSS_STATUS_UNAVAIL;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-23 00:37:47 +0000