Improve apparmor and selinux support.

Signed-off-by: Lantao Liu <lantaol@google.com>

vendor/github.com/opencontainers/runc/libcontainer/apparmor/apparmor.go

@@ -0,0 +1,39 @@
+// +build apparmor,linux
+
+package apparmor
+
+// #cgo LDFLAGS: -lapparmor
+// #include <sys/apparmor.h>
+// #include <stdlib.h>
+import "C"
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"unsafe"
+)
+
+// IsEnabled returns true if apparmor is enabled for the host.
+func IsEnabled() bool {
+	if _, err := os.Stat("/sys/kernel/security/apparmor"); err == nil && os.Getenv("container") == "" {
+		if _, err = os.Stat("/sbin/apparmor_parser"); err == nil {
+			buf, err := ioutil.ReadFile("/sys/module/apparmor/parameters/enabled")
+			return err == nil && len(buf) > 1 && buf[0] == 'Y'
+		}
+	}
+	return false
+}
+
+// ApplyProfile will apply the profile with the specified name to the process after
+// the next exec.
+func ApplyProfile(name string) error {
+	if name == "" {
+		return nil
+	}
+	cName := C.CString(name)
+	defer C.free(unsafe.Pointer(cName))
+	if _, err := C.aa_change_onexec(cName); err != nil {
+		return fmt.Errorf("apparmor failed to apply profile: %s", err)
+	}
+	return nil
+}

vendor/github.com/opencontainers/runc/libcontainer/apparmor/apparmor_disabled.go

@@ -0,0 +1,20 @@
+// +build !apparmor !linux
+
+package apparmor
+
+import (
+	"errors"
+)
+
+var ErrApparmorNotEnabled = errors.New("apparmor: config provided but apparmor not supported")
+
+func IsEnabled() bool {
+	return false
+}
+
+func ApplyProfile(name string) error {
+	if name != "" {
+		return ErrApparmorNotEnabled
+	}
+	return nil
+}