attestation: tdx issuer/validator (#1265)

* Add TDX validator

* Add TDX issuer

---------

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

internal/config/config.go

@@ -885,6 +885,37 @@ func (c QEMUVTPM) EqualTo(other AttestationCfg) (bool, error) {
 	return c.Measurements.EqualTo(otherCfg.Measurements), nil
 }
 
+// QEMUTDX is the configuration for QEMU TDX attestation.
+type QEMUTDX struct {
+	// description: |
+	//   Expected TDX measurements.
+	Measurements measurements.M `json:"measurements" yaml:"measurements" validate:"required,no_placeholders"`
+}
+
+// GetVariant returns qemu-tdx as the variant.
+func (QEMUTDX) GetVariant() variant.Variant {
+	return variant.QEMUTDX{}
+}
+
+// GetMeasurements returns the measurements used for attestation.
+func (c QEMUTDX) GetMeasurements() measurements.M {
+	return c.Measurements
+}
+
+// SetMeasurements updates a config's measurements using the given measurements.
+func (c *QEMUTDX) SetMeasurements(m measurements.M) {
+	c.Measurements = m
+}
+
+// EqualTo returns true if the config is equal to the given config.
+func (c QEMUTDX) EqualTo(other AttestationCfg) (bool, error) {
+	otherCfg, ok := other.(*QEMUTDX)
+	if !ok {
+		return false, fmt.Errorf("cannot compare %T with %T", c, other)
+	}
+	return c.Measurements.EqualTo(otherCfg.Measurements), nil
+}
+
 func toPtr[T any](v T) *T {
 	return &v
 }