container/init: configure interface lo

This enables loopback networking when owning the net namespace.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/dispatcher.go

@@ -61,6 +61,8 @@ type syscallDispatcher interface {
 	mountTmpfs(fsname, target string, flags uintptr, size int, perm os.FileMode) error
 	// ensureFile provides ensureFile.
 	ensureFile(name string, perm, pperm os.FileMode) error
+	// mustLoopback provides mustLoopback.
+	mustLoopback(msg message.Msg)
 
 	// seccompLoad provides [seccomp.Load].
 	seccompLoad(rules []std.NativeRule, flags seccomp.ExportFlag) error
@@ -164,6 +166,7 @@ func (k direct) mountTmpfs(fsname, target string, flags uintptr, size int, perm
 func (direct) ensureFile(name string, perm, pperm os.FileMode) error {
 	return ensureFile(name, perm, pperm)
 }
+func (direct) mustLoopback(msg message.Msg) { mustLoopback(msg) }
 
 func (direct) seccompLoad(rules []std.NativeRule, flags seccomp.ExportFlag) error {
 	return seccomp.Load(rules, flags)