1 files changed, 99 insertions, 0 deletions
diff --git a/src/resolve/resolved.c b/src/resolve/resolved.c
new file mode 100644
index 0000000..fd9be30
--- /dev/null
+++ b/src/resolve/resolved.c
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "sd-daemon.h"
+#include "sd-event.h"
+
+#include "bus-log-control-api.h"
+#include "capability-util.h"
+#include "daemon-util.h"
+#include "main-func.h"
+#include "mkdir.h"
+#include "resolved-bus.h"
+#include "resolved-conf.h"
+#include "resolved-manager.h"
+#include "resolved-resolv-conf.h"
+#include "selinux-util.h"
+#include "service-util.h"
+#include "signal-util.h"
+#include "user-util.h"
+
+static int run(int argc, char *argv[]) {
+        _cleanup_(manager_freep) Manager *m = NULL;
+        _cleanup_(notify_on_cleanup) const char *notify_stop = NULL;
+        int r;
+
+        log_setup_service();
+
+        r = service_parse_argv("systemd-resolved.service",
+                               "Provide name resolution with caching using DNS, mDNS, LLMNR.",
+                               BUS_IMPLEMENTATIONS(&manager_object,
+                                                   &log_control_object),
+                               argc, argv);
+        if (r <= 0)
+                return r;
+
+        umask(0022);
+
+        r = mac_selinux_init();
+        if (r < 0)
+                return r;
+
+        /* Drop privileges, but only if we have been started as root. If we are not running as root we assume most
+         * privileges are already dropped and we can't create our directory. */
+        if (getuid() == 0) {
+                const char *user = "systemd-resolve";
+                uid_t uid;
+                gid_t gid;
+
+                r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0);
+                if (r < 0)
+                        return log_error_errno(r, "Cannot resolve user name %s: %m", user);
+
+                /* As we're root, we can create the directory where resolv.conf will live */
+                r = mkdir_safe_label("/run/systemd/resolve", 0755, uid, gid, MKDIR_WARN_MODE);
+                if (r < 0)
+                        return log_error_errno(r, "Could not create runtime directory: %m");
+
+                /* Drop privileges, but keep three caps. Note that we drop those too, later on (see below) */
+                r = drop_privileges(uid, gid,
+                                    (UINT64_C(1) << CAP_NET_RAW)|          /* needed for SO_BINDTODEVICE */
+                                    (UINT64_C(1) << CAP_NET_BIND_SERVICE)| /* needed to bind on port 53 */
+                                    (UINT64_C(1) << CAP_SETPCAP)           /* needed in order to drop the caps later */);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to drop privileges: %m");
+        }
+
+        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);
+
+        r = manager_new(&m);
+        if (r < 0)
+                return log_error_errno(r, "Could not create manager: %m");
+
+        r = manager_start(m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to start manager: %m");
+
+        /* Write finish default resolv.conf to avoid a dangling symlink */
+        (void) manager_write_resolv_conf(m);
+
+        (void) manager_check_resolv_conf(m);
+
+        /* Let's drop the remaining caps now */
+        r = capability_bounding_set_drop(0, true);
+        if (r < 0)
+                return log_error_errno(r, "Failed to drop remaining caps: %m");
+
+        notify_stop = notify_start(NOTIFY_READY, NOTIFY_STOPPING);
+
+        r = sd_event_loop(m->event);
+        if (r < 0)
+                return log_error_errno(r, "Event loop failed: %m");
+
+        return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);