1 files changed, 43 insertions, 0 deletions
diff --git a/src/shared/fileio-label.c b/src/shared/fileio-label.c
new file mode 100644
index 0000000..572b8f6
--- /dev/null
+++ b/src/shared/fileio-label.c
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/stat.h>
+
+#include "fileio-label.h"
+#include "fileio.h"
+#include "selinux-util.h"
+
+int write_string_file_atomic_label_ts(const char *fn, const char *line, struct timespec *ts) {
+        int r;
+
+        r = mac_selinux_create_file_prepare(fn, S_IFREG);
+        if (r < 0)
+                return r;
+
+        r = write_string_file_ts(fn, line, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC, ts);
+
+        mac_selinux_create_file_clear();
+
+        return r;
+}
+
+int create_shutdown_run_nologin_or_warn(void) {
+        int r;
+
+        /* This is used twice: once in systemd-user-sessions.service, in order to block logins when we
+         * actually go down, and once in systemd-logind.service when shutdowns are scheduled, and logins are
+         * to be turned off a bit in advance. We use the same wording of the message in both cases.
+         *
+         * Traditionally, there was only /etc/nologin, and we managed that. Then, in PAM 1.1
+         * support for /run/nologin was added as alternative
+         * (https://github.com/linux-pam/linux-pam/commit/e9e593f6ddeaf975b7fe8446d184e6bc387d450b).
+         * 13 years later we stopped managing /etc/nologin, leaving it for the administrator to manage.
+         */
+
+        r = write_string_file_atomic_label("/run/nologin",
+                                           "System is going down. Unprivileged users are not permitted to log in anymore. "
+                                           "For technical details, see pam_nologin(8).");
+        if (r < 0)
+                return log_error_errno(r, "Failed to create /run/nologin: %m");
+
+        return 0;
+}