core: add a new GetUnitByControlGroup() bus call

This is useful for foreign container runtimes implementing the OCI
runtime spec, which only wants to deal with cgroup paths. There's
already an API to translate units into cgroup paths, with this we add
the reverse.

diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index de3f9db445043c68b76f2402d02f6d1e5b1b26de..d5a9f524eae3df5d6754e4bd28e81ed04aefa5d2 100644 (file)
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -544,6 +544,32 @@ static int method_get_unit_by_invocation_id(sd_bus_message *message, void *userd
         return sd_bus_reply_method_return(message, "o", path);
 }
 
+static int method_get_unit_by_control_group(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        _cleanup_free_ char *path = NULL;
+        Manager *m = userdata;
+        const char *cgroup;
+        Unit *u;
+        int r;
+
+        r = sd_bus_message_read(message, "s", &cgroup);
+        if (r < 0)
+                return r;
+
+        u = manager_get_unit_by_cgroup(m, cgroup);
+        if (!u)
+                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_UNIT, "Control group '%s' is not valid or not managed by this instance", cgroup);
+
+        r = mac_selinux_unit_access_check(u, message, "status", error);
+        if (r < 0)
+                return r;
+
+        path = unit_dbus_path(u);
+        if (!path)
+                return -ENOMEM;
+
+        return sd_bus_reply_method_return(message, "o", path);
+}
+
 static int method_load_unit(sd_bus_message *message, void *userdata, sd_bus_error *error) {
         _cleanup_free_ char *path = NULL;
         Manager *m = userdata;
@@ -2539,6 +2565,7 @@ const sd_bus_vtable bus_manager_vtable[] = {
         SD_BUS_METHOD("GetUnit", "s", "o", method_get_unit, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("GetUnitByPID", "u", "o", method_get_unit_by_pid, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("GetUnitByInvocationID", "ay", "o", method_get_unit_by_invocation_id, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("GetUnitByControlGroup", "s", "o", method_get_unit_by_control_group, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("LoadUnit", "s", "o", method_load_unit, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("StartUnit", "ss", "o", method_start_unit, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("StartUnitReplace", "sss", "o", method_start_unit_replace, SD_BUS_VTABLE_UNPRIVILEGED),

diff --git a/src/core/org.freedesktop.systemd1.conf b/src/core/org.freedesktop.systemd1.conf
index 5e72fe7e8e76c36522ce8ecd99936e3ce5bbb5d8..0114128a5734f774012f7d7cd845152de3cfc92b 100644 (file)
--- a/src/core/org.freedesktop.systemd1.conf
+++ b/src/core/org.freedesktop.systemd1.conf
@@ -60,6 +60,10 @@
                        send_interface="org.freedesktop.systemd1.Manager"
                        send_member="GetUnitByInvocationID"/>
 
+                <allow send_destination="org.freedesktop.systemd1"
+                       send_interface="org.freedesktop.systemd1.Manager"
+                       send_member="GetUnitByControlGroup"/>
+
                 <allow send_destination="org.freedesktop.systemd1"
                        send_interface="org.freedesktop.systemd1.Manager"
                        send_member="LoadUnit"/>