core: pass details to polkit for some unit actions

The following details are passed:

- unit: the primary name of the unit upon which the action was
        invoked (i.e. after resolving any aliases);
- verb: one of 'start', 'stop', 'reload', 'restart', 'try-restart',
        'reload-or-restart', 'reload-or-try-restart', 'kill',
        'reset-failed', or 'set-property', corresponding to the
        systemctl verb used to invoke the action.

Typical use of these details in a polkit policy rule might be:

  // Allow alice to manage example.service;
  // fall back to implicit authorization otherwise.
  polkit.addRule(function(action, subject) {
      if (action.id == "org.freedesktop.systemd1.manage-units" &&
          action.lookup("unit") == "example.service" &&
          subject.user == "alice") {
          return polkit.Result.YES;
      }
  });

We also supply a custom polkit message that includes the unit's name and
the requested operation.

po/POTFILES.in

@@ -5,3 +5,4 @@ src/locale/org.freedesktop.locale1.policy.in
 src/login/org.freedesktop.login1.policy.in
 src/machine/org.freedesktop.machine1.policy.in
 src/timedate/org.freedesktop.timedate1.policy.in
+src/core/dbus-unit.c

src/basic/util.h

@@ -567,6 +567,7 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
                  void *arg);
 
 #define _(String) gettext (String)
+#define N_(String) String
 void init_gettext(void);
 bool is_locale_utf8(void);
 

src/core/dbus-unit.c

@@ -391,6 +391,29 @@ static int property_get_load_error(
         return sd_bus_message_append(reply, "(ss)", e.name, e.message);
 }
 
+static int bus_verify_manage_units_async_full(
+                Unit *u,
+                const char *verb,
+                int capability,
+                const char *polkit_message,
+                sd_bus_message *call,
+                sd_bus_error *error) {
+
+        const char *details[9] = {
+                "unit", u->id,
+                "verb", verb,
+        };
+
+        if (polkit_message) {
+                details[4] = "polkit.message";
+                details[5] = polkit_message;
+                details[6] = "polkit.gettext_domain";
+                details[7] = GETTEXT_PACKAGE;
+        }
+
+        return bus_verify_polkit_async(call, capability, "org.freedesktop.systemd1.manage-units", details, false, UID_INVALID, &u->manager->polkit_registry, error);
+}
+
 int bus_unit_method_start_generic(
                 sd_bus_message *message,
                 Unit *u,
@@ -400,6 +423,14 @@ int bus_unit_method_start_generic(
 
         const char *smode;
         JobMode mode;
+        _cleanup_free_ char *verb = NULL;
+        static const char *const polkit_message_for_job[_JOB_TYPE_MAX] = {
+                [JOB_START]       = N_("Authentication is required to start '$(unit)'."),
+                [JOB_STOP]        = N_("Authentication is required to stop '$(unit)'."),
+                [JOB_RELOAD]      = N_("Authentication is required to reload '$(unit)'."),
+                [JOB_RESTART]     = N_("Authentication is required to restart '$(unit)'."),
+                [JOB_TRY_RESTART] = N_("Authentication is required to restart '$(unit)'."),
+        };
         int r;
 
         assert(message);
@@ -418,7 +449,20 @@ int bus_unit_method_start_generic(
         if (mode < 0)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Job mode %s invalid", smode);
 
-        r = bus_verify_manage_units_async(u->manager, message, error);
+        if (reload_if_possible)
+                verb = strjoin("reload-or-", job_type_to_string(job_type), NULL);
+        else
+                verb = strdup(job_type_to_string(job_type));
+        if (!verb)
+                return -ENOMEM;
+
+        r = bus_verify_manage_units_async_full(
+                        u,
+                        verb,
+                        CAP_SYS_ADMIN,
+                        job_type < _JOB_TYPE_MAX ? polkit_message_for_job[job_type] : NULL,
+                        message,
+                        error);
         if (r < 0)
                 return r;
         if (r == 0)
@@ -484,7 +528,13 @@ int bus_unit_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *
         if (signo <= 0 || signo >= _NSIG)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Signal number out of range.");
 
-        r = bus_verify_manage_units_async_for_kill(u->manager, message, error);
+        r = bus_verify_manage_units_async_full(
+                        u,
+                        "kill",
+                        CAP_KILL,
+                        N_("Authentication is required to kill '$(unit)'."),
+                        message,
+                        error);
         if (r < 0)
                 return r;
         if (r == 0)
@@ -508,7 +558,13 @@ int bus_unit_method_reset_failed(sd_bus_message *message, void *userdata, sd_bus
         if (r < 0)
                 return r;
 
-        r = bus_verify_manage_units_async(u->manager, message, error);
+        r = bus_verify_manage_units_async_full(
+                        u,
+                        "reset-failed",
+                        CAP_SYS_ADMIN,
+                        N_("Authentication is required to reset the \"failed\" state of '$(unit)'."),
+                        message,
+                        error);
         if (r < 0)
                 return r;
         if (r == 0)
@@ -534,7 +590,13 @@ int bus_unit_method_set_properties(sd_bus_message *message, void *userdata, sd_b
         if (r < 0)
                 return r;
 
-        r = bus_verify_manage_units_async(u->manager, message, error);
+        r = bus_verify_manage_units_async_full(
+                        u,
+                        "set-property",
+                        CAP_SYS_ADMIN,
+                        N_("Authentication is required to set properties on '$(unit)'."),
+                        message,
+                        error);
         if (r < 0)
                 return r;
         if (r == 0)

src/core/dbus.c

@@ -1201,11 +1201,6 @@ int bus_verify_manage_units_async(Manager *m, sd_bus_message *call, sd_bus_error
         return bus_verify_polkit_async(call, CAP_SYS_ADMIN, "org.freedesktop.systemd1.manage-units", NULL, false, UID_INVALID, &m->polkit_registry, error);
 }
 
-/* Same as bus_verify_manage_unit_async(), but checks for CAP_KILL instead of CAP_SYS_ADMIN */
-int bus_verify_manage_units_async_for_kill(Manager *m, sd_bus_message *call, sd_bus_error *error) {
-        return bus_verify_polkit_async(call, CAP_KILL, "org.freedesktop.systemd1.manage-units", NULL, false, UID_INVALID, &m->polkit_registry, error);
-}
-
 int bus_verify_manage_unit_files_async(Manager *m, sd_bus_message *call, sd_bus_error *error) {
         return bus_verify_polkit_async(call, CAP_SYS_ADMIN, "org.freedesktop.systemd1.manage-unit-files", NULL, false, UID_INVALID, &m->polkit_registry, error);
 }

src/core/dbus.h

@@ -37,7 +37,6 @@ int bus_track_coldplug(Manager *m, sd_bus_track **t, char ***l);
 int bus_foreach_bus(Manager *m, sd_bus_track *subscribed2, int (*send_message)(sd_bus *bus, void *userdata), void *userdata);
 
 int bus_verify_manage_units_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
-int bus_verify_manage_units_async_for_kill(Manager *m, sd_bus_message *call, sd_bus_error *error);
 int bus_verify_manage_unit_files_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
 int bus_verify_reload_daemon_async(Manager *m, sd_bus_message *call, sd_bus_error *error);
 int bus_verify_set_environment_async(Manager *m, sd_bus_message *call, sd_bus_error *error);