✨ Add cipher suite support to gRPC server TLS config

pkg/server/grpc/options.go

@@ -5,11 +5,14 @@ import (
 	"fmt"
 	"math"
 	"os"
+	"strings"
 	"time"
 
 	"github.com/spf13/pflag"
 	"gopkg.in/yaml.v2"
 	"k8s.io/klog/v2"
+
+	pkgtls "open-cluster-management.io/sdk-go/pkg/tls"
 )
 
 type GRPCServerOptions struct {
@@ -18,6 +21,7 @@ type GRPCServerOptions struct {
 	ClientCAFile            string        `json:"client_ca_file" yaml:"client_ca_file"`
 	TLSMinVersion           uint16        `json:"tls_min_version" yaml:"tls_min_version"`
 	TLSMaxVersion           uint16        `json:"tls_max_version" yaml:"tls_max_version"`
+	CipherSuites            []string      `json:"cipher_suites" yaml:"cipher_suites"`
 	ServerBindPort          string        `json:"server_bind_port" yaml:"server_bind_port"`
 	MaxConcurrentStreams    uint32        `json:"max_concurrent_streams" yaml:"max_concurrent_streams"`
 	MaxReceiveMessageSize   int           `json:"max_receive_message_size" yaml:"max_receive_message_size"`
@@ -31,6 +35,9 @@ type GRPCServerOptions struct {
 	ServerPingTimeout       time.Duration `json:"server_ping_timeout" yaml:"server_ping_timeout"`
 	PermitPingWithoutStream bool          `json:"permit_ping_without_stream" yaml:"permit_ping_without_stream"`
 	CertWatchInterval       time.Duration `json:"cert_watch_interval" yaml:"cert_watch_interval"`
+
+	// cipherSuiteIDs holds the parsed uint16 IDs from CipherSuites, populated by Validate().
+	cipherSuiteIDs []uint16
 }
 
 func LoadGRPCServerOptions(configPath string) (*GRPCServerOptions, error) {
@@ -110,5 +117,41 @@ func (o *GRPCServerOptions) Validate() error {
 	if o.CertWatchInterval <= 30*time.Second {
 		return fmt.Errorf("cert_watch_interval (%v) must be greater than 30 seconds", o.CertWatchInterval)
 	}
+
+	return o.validateCipherSuites()
+}
+
+// ApplyTLSFlags overrides TLS settings loaded from the config file with values
+// from --tls-min-version and --tls-cipher-suites command-line flags.
+// Called after LoadGRPCServerOptions so flags take precedence over the config file.
+func (o *GRPCServerOptions) ApplyTLSFlags(minVersion, cipherSuites string) error {
+	if minVersion != "" {
+		ver, err := pkgtls.ParseTLSVersion(minVersion)
+		if err != nil {
+			return fmt.Errorf("invalid --tls-min-version: %w", err)
+		}
+		o.TLSMinVersion = ver
+	}
+	if cipherSuites != "" {
+		o.CipherSuites = strings.Split(cipherSuites, ",")
+		for i := range o.CipherSuites {
+			o.CipherSuites[i] = strings.TrimSpace(o.CipherSuites[i])
+		}
+	}
+	return o.Validate()
+}
+
+// validateCipherSuites parses CipherSuites IANA names into uint16 IDs
+// using the shared pkg/tls parsing utilities.
+func (o *GRPCServerOptions) validateCipherSuites() error {
+	if len(o.CipherSuites) == 0 {
+		return nil
+	}
+	cipherString := strings.Join(o.CipherSuites, ",")
+	ids, unsupported := pkgtls.ParseCipherSuites(cipherString)
+	if len(unsupported) > 0 {
+		return fmt.Errorf("unrecognized cipher suite: %s", unsupported[0])
+	}
+	o.cipherSuiteIDs = ids
 	return nil
 }

pkg/server/grpc/options_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 )
 
 func TestLoadGRPCServerOptions(t *testing.T) {
@@ -173,12 +174,12 @@ connection_timeout: 90s
 				t.Fatalf("Unexpected error: %v", err)
 			}
 
-			if !cmp.Equal(opts, tc.expectedOpts) {
+			if !cmp.Equal(opts, tc.expectedOpts, cmpopts.IgnoreUnexported(GRPCServerOptions{})) {
 				t.Errorf("Loaded options do not match expected options.\nGot: %+v\nWant:%+v", opts, tc.expectedOpts)
 			}
 
 			if tc.checkDefaults {
-				if !cmp.Equal(opts, defaultOpts) {
+				if !cmp.Equal(opts, defaultOpts, cmpopts.IgnoreUnexported(GRPCServerOptions{})) {
 					t.Errorf("Expected default options, but got different values.\nGot: %+v\nWant:%+v", opts, defaultOpts)
 				}
 			}
@@ -239,6 +240,126 @@ func TestGRPCServerOptions_Validate_CertWatchInterval(t *testing.T) {
 	}
 }
 
+func TestApplyTLSFlags(t *testing.T) {
+	tests := []struct {
+		name            string
+		minVersion      string
+		cipherSuites    string
+		expectErr       bool
+		errorContains   string
+		expectedMinVer  uint16
+		expectedCiphers []string
+	}{
+		{
+			name:           "valid min version override",
+			minVersion:     "VersionTLS13",
+			expectedMinVer: tls.VersionTLS13,
+		},
+		{
+			name:           "valid TLSv format",
+			minVersion:     "TLSv1.3",
+			expectedMinVer: tls.VersionTLS13,
+		},
+		{
+			name:            "valid cipher suite override",
+			cipherSuites:    "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
+			expectedMinVer:  tls.VersionTLS12,
+			expectedCiphers: []string{"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"},
+		},
+		{
+			name:          "invalid min version",
+			minVersion:    "VersionTLS99",
+			expectErr:     true,
+			errorContains: "unknown TLS version",
+		},
+		{
+			name:          "unrecognized cipher name",
+			cipherSuites:  "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,BOGUS-CIPHER",
+			expectErr:     true,
+			errorContains: "unrecognized cipher suite",
+		},
+		{
+			name:            "both min version and ciphers",
+			minVersion:      "VersionTLS12",
+			cipherSuites:    "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
+			expectedMinVer:  tls.VersionTLS12,
+			expectedCiphers: []string{"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256"},
+		},
+		{
+			name:           "empty strings are no-ops",
+			minVersion:     "",
+			cipherSuites:   "",
+			expectedMinVer: tls.VersionTLS12,
+		},
+		{
+			name:            "flags override config file values",
+			minVersion:      "VersionTLS12",
+			cipherSuites:    "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
+			expectedMinVer:  tls.VersionTLS12,
+			expectedCiphers: []string{"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			opts := NewGRPCServerOptions()
+
+			err := opts.ApplyTLSFlags(tt.minVersion, tt.cipherSuites)
+
+			if tt.expectErr {
+				if err == nil {
+					t.Fatalf("expected error but got none")
+				}
+				if tt.errorContains != "" && !contains(err.Error(), tt.errorContains) {
+					t.Errorf("expected error to contain %q, got: %v", tt.errorContains, err)
+				}
+				return
+			}
+
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			if opts.TLSMinVersion != tt.expectedMinVer {
+				t.Errorf("expected TLSMinVersion %d, got %d", tt.expectedMinVer, opts.TLSMinVersion)
+			}
+
+			if len(tt.expectedCiphers) > 0 {
+				if len(opts.CipherSuites) != len(tt.expectedCiphers) {
+					t.Errorf("expected %d cipher suites, got %d", len(tt.expectedCiphers), len(opts.CipherSuites))
+				}
+				if len(opts.cipherSuiteIDs) != len(tt.expectedCiphers) {
+					t.Errorf("expected %d parsed cipher IDs, got %d", len(tt.expectedCiphers), len(opts.cipherSuiteIDs))
+				}
+			}
+		})
+	}
+}
+
+func TestApplyTLSFlags_OverridesConfigFile(t *testing.T) {
+	opts := NewGRPCServerOptions()
+	// Simulate config file values
+	opts.TLSMinVersion = tls.VersionTLS12
+	opts.CipherSuites = []string{"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256"}
+
+	// Flags override
+	err := opts.ApplyTLSFlags("VersionTLS13",
+		"TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if opts.TLSMinVersion != tls.VersionTLS13 {
+		t.Errorf("expected TLSMinVersion TLS 1.3, got %d", opts.TLSMinVersion)
+	}
+	if len(opts.CipherSuites) != 2 {
+		t.Errorf("expected 2 cipher suites, got %d", len(opts.CipherSuites))
+	}
+	if len(opts.cipherSuiteIDs) != 2 {
+		t.Errorf("expected 2 parsed cipher IDs, got %d", len(opts.cipherSuiteIDs))
+	}
+}
+
 func contains(s, substr string) bool {
 	return len(s) >= len(substr) && (s == substr || len(substr) == 0 ||
 		(len(s) > 0 && len(substr) > 0 && findSubstring(s, substr)))

pkg/server/grpc/server.go

@@ -110,6 +110,11 @@ func (b *GRPCServer) Run(ctx context.Context) error {
 		MaxVersion:     b.options.TLSMaxVersion,
 	}
 
+	// TLS 1.3 cipher suites are not configurable in Go — only set for TLS 1.2 and below.
+	if len(b.options.cipherSuiteIDs) > 0 && b.options.TLSMinVersion < tls.VersionTLS13 {
+		tlsConfig.CipherSuites = b.options.cipherSuiteIDs
+	}
+
 	if b.options.ClientCAFile != "" {
 		certPool := x509.NewCertPool()
 		caPEM, err := os.ReadFile(b.options.ClientCAFile)

pkg/tls/config.go

@@ -60,8 +60,10 @@ type TLSConfig struct {
 	CipherSuites []uint16
 }
 
-// parseTLSVersion converts a TLS version string to the corresponding crypto/tls constant
-func parseTLSVersion(version string) (uint16, error) {
+// ParseTLSVersion converts a TLS version string to the corresponding crypto/tls constant.
+// Accepted formats: "VersionTLS10"/"TLSv1.0" through "VersionTLS13"/"TLSv1.3".
+// An empty string defaults to TLS 1.2.
+func ParseTLSVersion(version string) (uint16, error) {
 	version = strings.TrimSpace(version)
 	switch version {
 	case "VersionTLS10", "TLSv1.0":
@@ -78,11 +80,11 @@ func parseTLSVersion(version string) (uint16, error) {
 	}
 }
 
-// parseCipherSuites converts IANA cipher suite names to Go crypto/tls constants.
+// ParseCipherSuites converts IANA cipher suite names to Go crypto/tls constants.
 // Secure ciphers (tls.CipherSuites) are accepted silently. Insecure ciphers
 // (tls.InsecureCipherSuites) are accepted but logged as a warning.
 // Returns a list of cipher suite IDs and a list of unrecognized cipher names.
-func parseCipherSuites(cipherString string) ([]uint16, []string) {
+func ParseCipherSuites(cipherString string) ([]uint16, []string) {
 	if strings.TrimSpace(cipherString) == "" {
 		return nil, nil
 	}
@@ -132,7 +134,7 @@ func ConfigFromFlags(minVersion, cipherSuites string) (*TLSConfig, error) {
 
 	// Parse min version
 	if minVersion != "" {
-		ver, err := parseTLSVersion(minVersion)
+		ver, err := ParseTLSVersion(minVersion)
 		if err != nil {
 			return nil, fmt.Errorf("invalid --tls-min-version: %w", err)
 		}
@@ -143,7 +145,7 @@ func ConfigFromFlags(minVersion, cipherSuites string) (*TLSConfig, error) {
 
 	// Parse cipher suites
 	if cipherSuites != "" {
-		suites, unsupported := parseCipherSuites(cipherSuites)
+		suites, unsupported := ParseCipherSuites(cipherSuites)
 		if len(unsupported) > 0 {
 			return nil, fmt.Errorf("unsupported cipher suites: %v", unsupported)
 		}

pkg/tls/configmap.go

@@ -148,7 +148,7 @@ func parseTLSConfigFromConfigMap(cm *corev1.ConfigMap) (*TLSConfig, error) {
 		minVersionStr = defaultMinTLSVersion
 	}
 
-	minVersion, err := parseTLSVersion(minVersionStr)
+	minVersion, err := ParseTLSVersion(minVersionStr)
 	if err != nil {
 		return nil, fmt.Errorf("invalid minTLSVersion in ConfigMap: %w", err)
 	}
@@ -157,7 +157,7 @@ func parseTLSConfigFromConfigMap(cm *corev1.ConfigMap) (*TLSConfig, error) {
 	// Parse cipher suites
 	cipherSuitesStr := cm.Data[ConfigMapKeyCipherSuites]
 	if cipherSuitesStr != "" {
-		cipherSuites, unsupported := parseCipherSuites(cipherSuitesStr)
+		cipherSuites, unsupported := ParseCipherSuites(cipherSuitesStr)
 		if len(unsupported) > 0 {
 			klog.Warningf("Unsupported cipher suites in ConfigMap %s/%s: %v", cm.Namespace, cm.Name, unsupported)
 			if len(cipherSuites) == 0 {

pkg/tls/tls_test.go

@@ -848,7 +848,7 @@ func TestParseTLSVersion(t *testing.T) {
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
-			result, err := parseTLSVersion(tc.version)
+			result, err := ParseTLSVersion(tc.version)
 
 			if tc.expectError {
 				if err == nil {
@@ -932,7 +932,7 @@ func TestParseCipherSuites(t *testing.T) {
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
-			suites, unsupported := parseCipherSuites(tc.cipherString)
+			suites, unsupported := ParseCipherSuites(tc.cipherString)
 
 			if len(suites) != tc.expectedCount {
 				t.Errorf("expected %d cipher suites, got %d", tc.expectedCount, len(suites))