fix base64 error handling

provider/assume-role/github/jwk/base64.go

@@ -27,8 +27,25 @@ func (ctx *base64Context) decode(s string, name string) []byte {
 	src := ctx.src[:len(s)]
 	copy(src, s)
 	n, err := base64.RawURLEncoding.Decode(ctx.dst, src)
-	if err != nil && ctx.err != nil {
-		ctx.err = fmt.Errorf("jwk: failed to parse the parameter %s: %w", name, err)
+	if err != nil && ctx.err == nil {
+		ctx.err = &base64DecodeError{
+			name: name,
+			err:  err,
+		}
 	}
 	return ctx.dst[:n]
 }
+
+type base64DecodeError struct {
+	name string
+	err  error
+}
+
+// Error implements the error interface.
+func (err *base64DecodeError) Error() string {
+	return fmt.Sprintf("jwk: failed to parse the parameter %s: %v", err.name, err.err)
+}
+
+func (err *base64DecodeError) Unwrap() error {
+	return err.err
+}

provider/assume-role/github/jwk/ecdsa.go

@@ -28,11 +28,11 @@ type ecdsaPrivateKey struct {
 	privateKey ecdsa.PrivateKey
 }
 
-func (key *ecdsaPrivateKey) PrivateKey() interface{} {
+func (key *ecdsaPrivateKey) PrivateKey() any {
 	return &key.privateKey
 }
 
-func (key *ecdsaPrivateKey) PublicKey() interface{} {
+func (key *ecdsaPrivateKey) PublicKey() any {
 	return &key.privateKey.PublicKey
 }
 
@@ -116,7 +116,7 @@ type ecdsaPublicKey struct {
 	publicKey ecdsa.PublicKey
 }
 
-func (key *ecdsaPublicKey) PublicKey() interface{} {
+func (key *ecdsaPublicKey) PublicKey() any {
 	return &key.publicKey
 }
 

provider/assume-role/github/jwk/ed25519.go

@@ -51,29 +51,34 @@ func parseEd25519PrivateKey(data []byte) (Key, error) {
 	return &key, nil
 }
 
-func (key *ed25519PrivateKey) PrivateKey() interface{} {
+func (key *ed25519PrivateKey) PrivateKey() any {
 	return key.privateKey
 }
 
-func (key *ed25519PrivateKey) PublicKey() interface{} {
+func (key *ed25519PrivateKey) PublicKey() any {
 	return key.publicKey
 }
 
 func (key *ed25519PrivateKey) decode() error {
+	const keySize = ed25519.PrivateKeySize - ed25519.PublicKeySize
 	ctx := key.getContext()
 
 	privateKey := make([]byte, ed25519.PrivateKeySize)
 	data := ctx.decode(key.D, "d")
-	if len(data) != ed25519.PrivateKeySize-ed25519.PublicKeySize {
+	if ctx.err != nil {
+		return ctx.err
+	}
+	if copy(privateKey, data) != keySize {
 		return fmt.Errorf("jwk: the parameter d has invalid size")
 	}
-	copy(privateKey, data)
 
 	publicKey := ctx.decode(key.X, "x")
-	if len(publicKey) != ed25519.PublicKeySize {
+	if ctx.err != nil {
+		return ctx.err
+	}
+	if copy(privateKey[keySize:], publicKey) != ed25519.PublicKeySize {
 		return fmt.Errorf("jwk: the parameter x has invalid size")
 	}
-	copy(privateKey[32:], publicKey)
 
 	key.publicKey = ed25519.PublicKey(publicKey)
 	key.privateKey = ed25519.PrivateKey(privateKey)
@@ -103,7 +108,7 @@ type ed25519PublicKey struct {
 	publicKey ed25519.PublicKey
 }
 
-func (key *ed25519PublicKey) PublicKey() interface{} {
+func (key *ed25519PublicKey) PublicKey() any {
 	return key.publicKey
 }
 
@@ -138,11 +143,14 @@ func parseEd25519PublicKey(data []byte) (Key, error) {
 func (key *ed25519PublicKey) decode() error {
 	ctx := key.getContext()
 	data := ctx.decode(key.X, "x")
+	if ctx.err != nil {
+		return ctx.err
+	}
 	if len(data) != ed25519.PublicKeySize {
 		return fmt.Errorf("jwk: the parameter x has invalid size")
 	}
 	key.publicKey = ed25519.PublicKey(data)
-	return ctx.err
+	return nil
 }
 
 func (key *ed25519PublicKey) getContext() base64Context {

provider/assume-role/github/jwk/jwk.go

@@ -42,11 +42,11 @@ type Key interface {
 
 	// PrivateKey returns the private key.
 	// If the key doesn't contain any private key, it returns nil.
-	PrivateKey() interface{}
+	PrivateKey() any
 
 	// PublicKey returns the public key.
 	// If the key doesn't contain any public key, it returns nil.
-	PublicKey() interface{}
+	PublicKey() any
 }
 
 type commonKey struct {
@@ -115,11 +115,11 @@ func (key *commonKey) X509CertificateSHA256() string {
 	return key.X5tS256
 }
 
-func (key *commonKey) PrivateKey() interface{} {
+func (key *commonKey) PrivateKey() any {
 	return nil
 }
 
-func (key *commonKey) PublicKey() interface{} {
+func (key *commonKey) PublicKey() any {
 	return nil
 }
 

provider/assume-role/github/jwk/jwk_test.go

@@ -5,6 +5,7 @@ import (
 	"crypto/ed25519"
 	"crypto/elliptic"
 	"crypto/rsa"
+	"errors"
 	"reflect"
 	"testing"
 )
@@ -479,3 +480,113 @@ func BenchmarkKey_RFC8037AppendixA(b *testing.B) {
 		}
 	})
 }
+
+func TestKey_Base64Error(t *testing.T) {
+	t.Run("EC Private Key", func(t *testing.T) {
+		rawKey := `{"kty":"EC",` +
+			`"crv":"P-256",` +
+			`"x":"!!!INVALID BASE64!!!",` +
+			`"y":"!!!INVALID BASE64!!!",` +
+			`"use":"enc",` +
+			`"kid":"1"}`
+		var e *base64DecodeError
+		_, err := ParseKey([]byte(rawKey))
+		if !errors.As(err, &e) {
+			t.Errorf("want *base64DecodeError, got %T", err)
+		}
+		if e.err == nil {
+			t.Error("want not nil, got nil")
+		}
+		if e.name != "x" && e.name != "y" {
+			t.Errorf("want name is x or y, got %s", e.name)
+		}
+	})
+
+	t.Run("RFC 7517 A.2. Example Private Keys (EC)", func(t *testing.T) {
+		rawKey := `{"kty":"EC",` +
+			`"crv":"P-256",` +
+			`"x":"!!!INVALID BASE64!!!",` +
+			`"y":"!!!INVALID BASE64!!!",` +
+			`"d":"!!!INVALID BASE64!!!",` +
+			`"use":"enc",` +
+			`"kid":"1"}`
+		var e *base64DecodeError
+		_, err := ParseKey([]byte(rawKey))
+		if !errors.As(err, &e) {
+			t.Errorf("want *base64DecodeError, got %T", err)
+		}
+		if e.err == nil {
+			t.Error("want not nil, got nil")
+		}
+		if e.name != "x" && e.name != "y" && e.name != "d" {
+			t.Errorf("want name is x or y or d, got %s", e.name)
+		}
+	})
+
+	t.Run("RSA Public Key", func(t *testing.T) {
+		rawKey := `{"kty":"RSA",` +
+			`"n":"!!!INVALID BASE64!!!",` +
+			`"e":"!!!INVALID BASE64!!!",` +
+			`"alg":"RS256",` +
+			`"kid":"2011-04-29"}`
+		var e *base64DecodeError
+		_, err := ParseKey([]byte(rawKey))
+		if !errors.As(err, &e) {
+			t.Errorf("want *base64DecodeError, got %T", err)
+		}
+		if e.err == nil {
+			t.Error("want not nil, got nil")
+		}
+		if e.name != "n" && e.name != "e" {
+			t.Errorf("want name is n or e, got %s", e.name)
+		}
+	})
+
+	t.Run("Symmetric Keys (HMAC)", func(t *testing.T) {
+		rawKey := `{"kty":"oct","k":"!!!INVALID BASE64!!!"}`
+		var e *base64DecodeError
+		_, err := ParseKey([]byte(rawKey))
+		if !errors.As(err, &e) {
+			t.Errorf("want *base64DecodeError, got %T", err)
+		}
+		if e.err == nil {
+			t.Error("want not nil, got nil")
+		}
+		if e.name != "k" {
+			t.Errorf("want name is k, got %s", e.name)
+		}
+	})
+
+	t.Run("Ed25519 Public Key", func(t *testing.T) {
+		rawKey := `{"kty":"OKP","crv":"Ed25519",` +
+			`"x":"!!!INVALID BASE64!!!"}`
+		var e *base64DecodeError
+		_, err := ParseKey([]byte(rawKey))
+		if !errors.As(err, &e) {
+			t.Errorf("want *base64DecodeError, got %T", err)
+		}
+		if e.err == nil {
+			t.Error("want not nil, got nil")
+		}
+		if e.name != "x" {
+			t.Errorf("want name is x, got %s", e.name)
+		}
+	})
+
+	t.Run("Ed25519 Private Key", func(t *testing.T) {
+		rawKey := `{"kty":"OKP","crv":"Ed25519",` +
+			`"d":"!!!INVALID BASE64!!!",` +
+			`"x":"!!!INVALID BASE64!!!"}`
+		var e *base64DecodeError
+		_, err := ParseKey([]byte(rawKey))
+		if !errors.As(err, &e) {
+			t.Errorf("want *base64DecodeError, got %T", err)
+		}
+		if e.err == nil {
+			t.Error("want not nil, got nil")
+		}
+		if e.name != "d" && e.name != "x" {
+			t.Errorf("want name is d or x, got %s", e.name)
+		}
+	})
+}

provider/assume-role/github/jwk/rsa.go

@@ -77,11 +77,11 @@ func parseRSAPrivateKey(data []byte) (Key, error) {
 	return &key, nil
 }
 
-func (key *rsaPrivateKey) PrivateKey() interface{} {
+func (key *rsaPrivateKey) PrivateKey() any {
 	return &key.privateKey
 }
 
-func (key *rsaPrivateKey) PublicKey() interface{} {
+func (key *rsaPrivateKey) PublicKey() any {
 	return &key.privateKey.PublicKey
 }
 
@@ -192,7 +192,7 @@ type rsaPublicKey struct {
 	publicKey rsa.PublicKey
 }
 
-func (key *rsaPublicKey) PublicKey() interface{} {
+func (key *rsaPublicKey) PublicKey() any {
 	return &key.publicKey
 }
 

provider/assume-role/github/jwk/symmetric.go

@@ -1,9 +1,7 @@
 package jwk
 
 import (
-	"encoding/base64"
 	"encoding/json"
-	"fmt"
 )
 
 // RFC7518 6.4. Parameters for Symmetric Keys
@@ -30,17 +28,17 @@ func parseSymmetricKey(data []byte) (Key, error) {
 	return &key, nil
 }
 
-func (key *symmetricKey) PrivateKey() interface{} {
+func (key *symmetricKey) PrivateKey() any {
 	return key.key
 }
 
 // decode decodes the encoded values into publicKey.
 func (key *symmetricKey) decode() error {
-	k, err := base64.RawURLEncoding.DecodeString(key.K)
-	if err != nil {
-		return fmt.Errorf("jwk: failed to parse parameter k: %w", err)
-	}
-	key.key = k
+	ctx := key.getContext()
+	key.key = ctx.decode(key.K, "k")
+	return ctx.err
+}
 
-	return nil
+func (key *symmetricKey) getContext() base64Context {
+	return newBase64Context(len(key.K))
 }