Add attestationFormat property in the ACME provisioner

authority/provisioner/acme.go

@@ -41,6 +41,38 @@ func (c ACMEChallenge) Validate() error {
 	}
 }
 
+// ACMEPlatform represents the format used on a device-attest-01 challenge.
+type ACMEAttestationFormat string
+
+const (
+	// APPLE is the format used to enable device-attest-01 on apple devices.
+	APPLE ACMEAttestationFormat = "apple"
+
+	// STEP is the format used to enable device-attest-01 on devices that
+	// provide attestation certificates like the PIV interface on YubiKeys.
+	//
+	// TODO(mariano): should we rename this to something else.
+	STEP ACMEAttestationFormat = "step"
+
+	// TPM is the format used to enable device-attest-01 on TPMs.
+	TPM ACMEAttestationFormat = "tpm"
+)
+
+// String returns a normalized version of the attestation format.
+func (f ACMEAttestationFormat) String() string {
+	return strings.ToLower(string(f))
+}
+
+// Validate returns an error if the attestation format is not a valid one.
+func (f ACMEAttestationFormat) Validate() error {
+	switch ACMEAttestationFormat(f.String()) {
+	case APPLE, STEP, TPM:
+		return nil
+	default:
+		return fmt.Errorf("acme attestation format %q is not supported", f)
+	}
+}
+
 // ACME is the acme provisioner type, an entity that can authorize the ACME
 // provisioning flow.
 type ACME struct {
@@ -58,6 +90,10 @@ type ACME struct {
 	// value is not set the default http-01, dns-01 and tls-alpn-01 challenges
 	// will be enabled, device-attest-01 will be disabled.
 	Challenges []ACMEChallenge `json:"challenges,omitempty"`
+	// AttestationFormats contains the enabled attestation formats for this
+	// provisioner. If this value is not set the default apple, step and tpm
+	// will be used.
+	AttestationFormats []ACMEAttestationFormat `json:"attestationFormats,omitempty"`
 	Claims             *Claims                 `json:"claims,omitempty"`
 	Options            *Options                `json:"options,omitempty"`
 
@@ -123,6 +159,11 @@ func (p *ACME) Init(config Config) (err error) {
 			return err
 		}
 	}
+	for _, f := range p.AttestationFormats {
+		if err := f.Validate(); err != nil {
+			return err
+		}
+	}
 
 	p.ctl, err = NewController(p, p.Claims, config, p.Options)
 	return
@@ -222,3 +263,21 @@ func (p *ACME) IsChallengeEnabled(ctx context.Context, challenge ACMEChallenge)
 	}
 	return false
 }
+
+// IsAttestationFormatEnabled checks if the given attestation format is enabled.
+// By default apple, step and tpm are enabled, to disable any of them the
+// AttestationFormat provisioner property should have at least one element.
+func (p *ACME) IsAttestationFormatEnabled(ctx context.Context, format ACMEAttestationFormat) bool {
+	enabledFormats := []ACMEAttestationFormat{
+		APPLE, STEP, TPM,
+	}
+	if len(p.AttestationFormats) > 0 {
+		enabledFormats = p.AttestationFormats
+	}
+	for _, f := range enabledFormats {
+		if strings.EqualFold(string(f), string(format)) {
+			return true
+		}
+	}
+	return false
+}

authority/provisioner/acme_test.go

@@ -35,6 +35,27 @@ func TestACMEChallenge_Validate(t *testing.T) {
 	}
 }
 
+func TestACMEAttestationFormat_Validate(t *testing.T) {
+	tests := []struct {
+		name    string
+		f       ACMEAttestationFormat
+		wantErr bool
+	}{
+		{"apple", APPLE, false},
+		{"step", STEP, false},
+		{"tpm", TPM, false},
+		{"uppercase", "APPLE", false},
+		{"fail", "FOO", true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := tt.f.Validate(); (err != nil) != tt.wantErr {
+				t.Errorf("ACMEAttestationFormat.Validate() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}
+
 func TestACME_Getters(t *testing.T) {
 	p, err := generateACME()
 	assert.FatalError(t, err)
@@ -93,17 +114,24 @@ func TestACME_Init(t *testing.T) {
 				err: errors.New("acme challenge \"zar\" is not supported"),
 			}
 		},
+		"fail-bad-attestation-format": func(t *testing.T) ProvisionerValidateTest {
+			return ProvisionerValidateTest{
+				p:   &ACME{Name: "foo", Type: "bar", AttestationFormats: []ACMEAttestationFormat{APPLE, "zar"}},
+				err: errors.New("acme attestation format \"zar\" is not supported"),
+			}
+		},
 		"ok": func(t *testing.T) ProvisionerValidateTest {
 			return ProvisionerValidateTest{
 				p: &ACME{Name: "foo", Type: "bar"},
 			}
 		},
-		"ok with challenges": func(t *testing.T) ProvisionerValidateTest {
+		"ok attestation": func(t *testing.T) ProvisionerValidateTest {
 			return ProvisionerValidateTest{
 				p: &ACME{
 					Name:               "foo",
 					Type:               "bar",
 					Challenges:         []ACMEChallenge{DNS_01, DEVICE_ATTEST_01},
+					AttestationFormats: []ACMEAttestationFormat{APPLE, STEP},
 				},
 			}
 		},
@@ -282,3 +310,39 @@ func TestACME_IsChallengeEnabled(t *testing.T) {
 		})
 	}
 }
+
+func TestACME_IsAttestationFormatEnabled(t *testing.T) {
+	ctx := context.Background()
+	type fields struct {
+		AttestationFormats []ACMEAttestationFormat
+	}
+	type args struct {
+		ctx    context.Context
+		format ACMEAttestationFormat
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   bool
+	}{
+		{"ok", fields{[]ACMEAttestationFormat{APPLE, STEP, TPM}}, args{ctx, TPM}, true},
+		{"ok empty apple", fields{nil}, args{ctx, APPLE}, true},
+		{"ok empty step", fields{nil}, args{ctx, STEP}, true},
+		{"ok empty tpm", fields{[]ACMEAttestationFormat{}}, args{ctx, "tpm"}, true},
+		{"ok uppercase", fields{[]ACMEAttestationFormat{APPLE, STEP, TPM}}, args{ctx, "STEP"}, true},
+		{"fail apple", fields{[]ACMEAttestationFormat{STEP, TPM}}, args{ctx, APPLE}, false},
+		{"fail step", fields{[]ACMEAttestationFormat{APPLE, TPM}}, args{ctx, STEP}, false},
+		{"fail step", fields{[]ACMEAttestationFormat{APPLE, STEP}}, args{ctx, TPM}, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			p := &ACME{
+				AttestationFormats: tt.fields.AttestationFormats,
+			}
+			if got := p.IsAttestationFormatEnabled(tt.args.ctx, tt.args.format); got != tt.want {
+				t.Errorf("ACME.IsAttestationFormatEnabled() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}