Merge pull request #34686 from DaanDeMeyer/bus-fallback

Make sure bus_connect_transport_systemd() actually connects to the private manager bus

mkosi.extra/usr/lib/tmpfiles.d/testuser.conf

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+z! /home/testuser 700 testuser testuser

src/shared/bus-util.c

@@ -229,12 +229,6 @@ int bus_connect_system_systemd(sd_bus **ret_bus) {
 
         assert(ret_bus);
 
-        if (geteuid() != 0)
-                return sd_bus_default_system(ret_bus);
-
-        /* If we are root then let's talk directly to the system
-         * instance, instead of going via the bus */
-
         r = sd_bus_new(&bus);
         if (r < 0)
                 return r;
@@ -245,7 +239,7 @@ int bus_connect_system_systemd(sd_bus **ret_bus) {
 
         r = sd_bus_start(bus);
         if (r < 0)
-                return sd_bus_default_system(ret_bus);
+                return r;
 
         r = bus_check_peercred(bus);
         if (r < 0)
@@ -265,7 +259,7 @@ int bus_connect_user_systemd(sd_bus **ret_bus) {
 
         e = secure_getenv("XDG_RUNTIME_DIR");
         if (!e)
-                return sd_bus_default_user(ret_bus);
+                return -ENXIO;
 
         ee = bus_address_escape(e);
         if (!ee)
@@ -281,7 +275,7 @@ int bus_connect_user_systemd(sd_bus **ret_bus) {
 
         r = sd_bus_start(bus);
         if (r < 0)
-                return sd_bus_default_user(ret_bus);
+                return r;
 
         r = bus_check_peercred(bus);
         if (r < 0)
@@ -521,8 +515,13 @@ int bus_connect_transport_systemd(
                                 /* Print a friendly message when the local system is actually not running systemd as PID 1. */
                                 return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
                                                        "System has not been booted with systemd as init system (PID 1). Can't operate.");
-                        return bus_connect_system_systemd(ret_bus);
 
+                        if (geteuid() == 0)
+                                /* If we are root then let's talk directly to the system
+                                 * instance, instead of going via the bus. */
+                                return bus_connect_system_systemd(ret_bus);
+
+                        return sd_bus_default_system(ret_bus);
                 default:
                         assert_not_reached();
                 }

src/stdio-bridge/stdio-bridge.c

@@ -142,7 +142,7 @@ static int run(int argc, char *argv[]) {
 
         r = sd_bus_start(a);
         if (r < 0)
-                return log_error_errno(r, "Failed to start bus client: %m");
+                return bus_log_connect_error(r, arg_transport, arg_runtime_scope);
 
         r = sd_bus_get_bus_id(a, &server_id);
         if (r < 0)
@@ -170,7 +170,7 @@ static int run(int argc, char *argv[]) {
 
         r = sd_bus_start(b);
         if (r < 0)
-                return log_error_errno(r, "Failed to start bus client: %m");
+                return log_error_errno(r, "Failed to start bus forwarding server: %m");
 
         for (;;) {
                 _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;

src/update-utmp/update-utmp.c

@@ -82,6 +82,25 @@ static int get_current_runlevel(Context *c) {
         assert(c);
 
         for (unsigned n_attempts = 0;;) {
+                if (n_attempts++ > 0) {
+                        /* systemd might have dropped off momentarily, let's not make this an error,
+                        * and wait some random time. Let's pick a random time in the range 0ms…250ms,
+                        * linearly scaled by the number of failed attempts. */
+                        c->bus = sd_bus_flush_close_unref(c->bus);
+
+                        usec_t usec = random_u64_range(UINT64_C(10) * USEC_PER_MSEC +
+                                                UINT64_C(240) * USEC_PER_MSEC * n_attempts/64);
+                        (void) usleep_safe(usec);
+
+                        r = bus_connect_system_systemd(&c->bus);
+                        if (r == -ECONNREFUSED && n_attempts < 64) {
+                                log_debug_errno(r, "Failed to reconnect to system bus, retrying after a slight delay: %m");
+                                continue;
+                        }
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to reconnect to system bus: %m");
+                }
+
                 FOREACH_ELEMENT(e, table) {
                         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
                         _cleanup_free_ char *state = NULL, *path = NULL;
@@ -102,18 +121,10 @@ static int get_current_runlevel(Context *c) {
                              sd_bus_error_has_names(&error,
                                                     SD_BUS_ERROR_NO_REPLY,
                                                     SD_BUS_ERROR_DISCONNECTED)) &&
-                            ++n_attempts < 64) {
-
-                                /* systemd might have dropped off momentarily, let's not make this an error,
-                                 * and wait some random time. Let's pick a random time in the range 0ms…250ms,
-                                 * linearly scaled by the number of failed attempts. */
-
-                                usec_t usec = random_u64_range(UINT64_C(10) * USEC_PER_MSEC +
-                                                               UINT64_C(240) * USEC_PER_MSEC * n_attempts/64);
-                                log_debug_errno(r, "Failed to get state of %s, retrying after %s: %s",
-                                                e->special, FORMAT_TIMESPAN(usec, USEC_PER_MSEC), bus_error_message(&error, r));
-                                (void) usleep_safe(usec);
-                                goto reconnect;
+                            n_attempts < 64) {
+                                log_debug_errno(r, "Failed to get state of %s, retrying after a slight delay: %s",
+                                                e->special, bus_error_message(&error, r));
+                                break;
                         }
                         if (r < 0)
                                 return log_warning_errno(r, "Failed to get state of %s: %s", e->special, bus_error_message(&error, r));
@@ -121,14 +132,8 @@ static int get_current_runlevel(Context *c) {
                         if (STR_IN_SET(state, "active", "reloading"))
                                 return e->runlevel;
                 }
-
-                return 0;
-
-reconnect:
-                c->bus = sd_bus_flush_close_unref(c->bus);
-                r = bus_connect_system_systemd(&c->bus);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to reconnect to system bus: %m");
+                if (r >= 0)
+                        return 0;
         }
 }