diff --git a/libcontainer/nsinit/init.go b/libcontainer/nsinit/init.go index 3bbcfcc..85ca08c 100644 --- a/libcontainer/nsinit/init.go +++ b/libcontainer/nsinit/init.go @@ -85,12 +85,53 @@ func Init(container *libcontainer.Container, uncleanRootfs, consolePath string, return err } } + + pdeathSignal, err := system.GetParentDeathSignal() + if err != nil { + return fmt.Errorf("get parent death signal %s", err) + } + if err := FinalizeNamespace(container); err != nil { return fmt.Errorf("finalize namespace %s", err) } + + // FinalizeNamespace can change user/group which clears the parent death + // signal, so we restore it here. + if err := RestoreParentDeathSignal(pdeathSignal); err != nil { + return fmt.Errorf("restore parent death signal %s", err) + } + return system.Execv(args[0], args[0:], container.Env) } +// RestoreParentDeathSignal sets the parent death signal to old. +func RestoreParentDeathSignal(old int) error { + if old == 0 { + return nil + } + + current, err := system.GetParentDeathSignal() + if err != nil { + return fmt.Errorf("get parent death signal %s", err) + } + + if old == current { + return nil + } + + if err := system.ParentDeathSignal(uintptr(old)); err != nil { + return fmt.Errorf("set parent death signal %s", err) + } + + // Signal self if parent is already dead. Does nothing if running in a new + // PID namespace, as Getppid will always return 0. + if syscall.Getppid() == 1 { + return syscall.Kill(syscall.Getpid(), syscall.Signal(old)) + } + + return nil +} + // SetupUser changes the groups, gid, and uid for the user inside the container func SetupUser(u string) error { uid, gid, suppGids, err := user.GetUserGroupSupplementary(u, syscall.Getuid(), syscall.Getgid())