Add seccomp trace support

Closes #347

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

libcontainer/configs/config.go

@@ -33,17 +33,18 @@ type Seccomp struct {
 type Action int
 
 const (
-	Kill Action = iota - 4
+	Kill Action = iota + 1
 	Errno
 	Trap
 	Allow
+	Trace
 )
 
 // A comparison operator to be used when matching syscall arguments in Seccomp
 type Operator int
 
 const (
-	EqualTo Operator = iota
+	EqualTo Operator = iota + 1
 	NotEqualTo
 	GreaterThan
 	GreaterThanOrEqualTo

libcontainer/seccomp/config.go

@@ -21,6 +21,7 @@ var actions = map[string]configs.Action{
 	"SCMP_ACT_ERRNO": configs.Errno,
 	"SCMP_ACT_TRAP":  configs.Trap,
 	"SCMP_ACT_ALLOW": configs.Allow,
+	"SCMP_ACT_TRACE": configs.Trace,
 }
 
 var archs = map[string]string{

libcontainer/seccomp/seccomp_linux.go

@@ -15,6 +15,7 @@ var (
 	actAllow = libseccomp.ActAllow
 	actTrap  = libseccomp.ActTrap
 	actKill  = libseccomp.ActKill
+	actTrace = libseccomp.ActTrace.SetReturnCode(int16(syscall.EPERM))
 	actErrno = libseccomp.ActErrno.SetReturnCode(int16(syscall.EPERM))
 )
 
@@ -83,6 +84,8 @@ func getAction(act configs.Action) (libseccomp.ScmpAction, error) {
 		return actTrap, nil
 	case configs.Allow:
 		return actAllow, nil
+	case configs.Trace:
+		return actTrace, nil
 	default:
 		return libseccomp.ActInvalid, fmt.Errorf("invalid action, cannot use in rule")
 	}