diff --git a/libcontainer/nsinit/init.go b/libcontainer/nsinit/init.go index 8139865..0f1f484 100644 --- a/libcontainer/nsinit/init.go +++ b/libcontainer/nsinit/init.go @@ -172,15 +172,33 @@ func setupNetwork(container *libcontainer.Container, context libcontainer.Contex // and working dir, and closes any leaky file descriptors // before execing the command inside the namespace func FinalizeNamespace(container *libcontainer.Container) error { - if err := capabilities.DropCapabilities(container); err != nil { - return fmt.Errorf("drop capabilities %s", err) - } if err := system.CloseFdsFrom(3); err != nil { return fmt.Errorf("close open file descriptors %s", err) } + + // drop capabilities in bounding set before changing user + if err := capabilities.DropBoundingSet(container); err != nil { + return fmt.Errorf("drop bounding set %s", err) + } + + // preserve existing capabilities while we change users + if err := system.SetKeepCaps(); err != nil { + return fmt.Errorf("set keep caps %s", err) + } + if err := SetupUser(container.User); err != nil { return fmt.Errorf("setup user %s", err) } + + if err := system.ClearKeepCaps(); err != nil { + return fmt.Errorf("clear keep caps %s", err) + } + + // drop all other capabilities + if err := capabilities.DropCapabilities(container); err != nil { + return fmt.Errorf("drop capabilities %s", err) + } + if container.WorkingDir != "" { if err := system.Chdir(container.WorkingDir); err != nil { return fmt.Errorf("chdir to %s %s", container.WorkingDir, err) diff --git a/libcontainer/security/capabilities/capabilities.go b/libcontainer/security/capabilities/capabilities.go index ba72070..64ea961 100644 --- a/libcontainer/security/capabilities/capabilities.go +++ b/libcontainer/security/capabilities/capabilities.go @@ -9,6 +9,25 @@ import ( const allCapabilityTypes = capability.CAPS | capability.BOUNDS +// DropBoundingSet drops the capability bounding set to those specified in the +// container configuration. +func DropBoundingSet(container *libcontainer.Container) error { + c, err := capability.NewPid(os.Getpid()) + if err != nil { + return err + } + + keep := getEnabledCapabilities(container) + c.Clear(capability.BOUNDS) + c.Set(capability.BOUNDS, keep...) + + if err := c.Apply(capability.BOUNDS); err != nil { + return err + } + + return nil +} + // DropCapabilities drops all capabilities for the current process expect those specified in the container configuration. func DropCapabilities(container *libcontainer.Container) error { c, err := capability.NewPid(os.Getpid())