fix: role extraction from access token in keycloak oidc (#1916)

* Fix wrong token used in Keycloak OIDC provider

* Update CHANGELOG for PR #1916

* Update tests

* fix: keycloak oidc role extraction

---------

Co-authored-by: Jan Larwig <jan@larwig.com>

CHANGELOG.md

@@ -11,6 +11,7 @@
 - [#3031](https://github.com/oauth2-proxy/oauth2-proxy/pull/3031) Fixes Refresh Token bug with Entra ID and Workload Identity (#3027)[https://github.com/oauth2-proxy/oauth2-proxy/issues/3028] by using client assertion when redeeming the token (@richard87)
 - [#3001](https://github.com/oauth2-proxy/oauth2-proxy/pull/3001) Allow to set non-default authorization request response mode (@stieler-it)
 - [#3041](https://github.com/oauth2-proxy/oauth2-proxy/pull/3041) chore(deps): upgrade to latest golang v1.23.x release (@TheImplementer)
+- [#1916](https://github.com/oauth2-proxy/oauth2-proxy/pull/1916) fix: role extraction from access token in keycloak oidc (@Elektordi / @tuunit)
 
 # V7.8.2
 

providers/keycloak_oidc.go

@@ -2,7 +2,10 @@ package providers
 
 import (
 	"context"
+	"encoding/base64"
+	"encoding/json"
 	"fmt"
+	"strings"
 
 	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/apis/options"
 	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/apis/sessions"
@@ -51,7 +54,7 @@ func (p *KeycloakOIDCProvider) CreateSessionFromToken(ctx context.Context, token
 	}
 
 	// Extract custom keycloak roles and enrich session
-	if err := p.extractRoles(ctx, ss); err != nil {
+	if err := p.extractRoles(ss); err != nil {
 		return nil, err
 	}
 
@@ -65,7 +68,7 @@ func (p *KeycloakOIDCProvider) EnrichSession(ctx context.Context, s *sessions.Se
 	if err != nil {
 		return fmt.Errorf("could not enrich oidc session: %v", err)
 	}
-	return p.extractRoles(ctx, s)
+	return p.extractRoles(s)
 }
 
 // RefreshSession adds role extraction logic to the refresh flow
@@ -77,11 +80,11 @@ func (p *KeycloakOIDCProvider) RefreshSession(ctx context.Context, s *sessions.S
 		return refreshed, err
 	}
 
-	return true, p.extractRoles(ctx, s)
+	return true, p.extractRoles(s)
 }
 
-func (p *KeycloakOIDCProvider) extractRoles(ctx context.Context, s *sessions.SessionState) error {
+func (p *KeycloakOIDCProvider) extractRoles(s *sessions.SessionState) error {
-	claims, err := p.getAccessClaims(ctx, s)
+	claims, err := p.getAccessClaims(s)
 	if err != nil {
 		return err
 	}
@@ -106,18 +109,22 @@ type accessClaims struct {
 	ResourceAccess map[string]interface{} `json:"resource_access"`
 }
 
-func (p *KeycloakOIDCProvider) getAccessClaims(ctx context.Context, s *sessions.SessionState) (*accessClaims, error) {
+func (p *KeycloakOIDCProvider) getAccessClaims(s *sessions.SessionState) (*accessClaims, error) {
-	// HACK: This isn't an ID Token, but has similar structure & signing
+	parts := strings.Split(s.AccessToken, ".")
-	token, err := p.Verifier.Verify(ctx, s.AccessToken)
+	if len(parts) < 2 {
-	if err != nil {
+		return nil, fmt.Errorf("malformed access token, expected 3 parts got %d", len(parts))
-		return nil, err
 	}
 
-	var claims *accessClaims
+	payload, err := base64.RawURLEncoding.DecodeString(parts[1])
-	if err = token.Claims(&claims); err != nil {
+	if err != nil {
+		return nil, fmt.Errorf("malformed access token, couldn't extract jwt payload: %v", err)
+	}
+
+	var claims accessClaims
+	if err := json.Unmarshal(payload, &claims); err != nil {
 		return nil, err
 	}
-	return claims, nil
+	return &claims, nil
 }
 
 // getClientRoles extracts client roles from the `resource_access` claim with

providers/keycloak_oidc_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http/httptest"
 	"net/url"
+	"strings"
 
 	"github.com/coreos/go-oidc/v3/oidc"
 
@@ -18,28 +19,40 @@ import (
 )
 
 const (
+	idTokenHeader        = "eyJhbGciOiJSUzI1NiIsInR5cCIgOiAiSldUIiwia2lkIiA6ICJjV1IteTRzRVU1MjZVelk1SFd6UEZJbWdMMWRKUllfQ0gyY1FFRXh4UGN3In0"
+	idTokenSignature     = "Rh0zQGhWAm-2hn5JTWB3Lzuk9Ahpzs7As7ks-1VInl4"
 	accessTokenHeader    = "ewogICJhbGciOiAiUlMyNTYiLAogICJ0eXAiOiAiSldUIgp9"
 	accessTokenSignature = "dyt0CoTl4WoVjAHI9Q_CwSKhl6d_9rhM3NrXuJttkao"
 	defaultAudienceClaim = "aud"
 	mockClientID         = "cd6d4fae-f6a6-4a34-8454-2c6b598e9532"
 )
 
-var accessTokenPayload = base64.StdEncoding.EncodeToString([]byte(
+var (
+	accessTokenPayload = base64.RawURLEncoding.EncodeToString([]byte(
 		fmt.Sprintf(`{"%s": "%s", "realm_access": {"roles": ["write"]}, "resource_access": {"default": {"roles": ["read"]}}}`, defaultAudienceClaim, mockClientID)))
 
+	idTokenPayload = base64.RawURLEncoding.EncodeToString([]byte(
+		fmt.Sprintf(`{"%s": "%s"}`, defaultAudienceClaim, mockClientID)))
+)
+
 type DummyKeySet struct{}
 
-func (DummyKeySet) VerifySignature(_ context.Context, _ string) (payload []byte, err error) {
+func (DummyKeySet) VerifySignature(_ context.Context, jwt string) (payload []byte, err error) {
-	p, _ := base64.RawURLEncoding.DecodeString(accessTokenPayload)
+	parts := strings.Split(jwt, ".")
+	p, _ := base64.RawURLEncoding.DecodeString(parts[1])
 	return p, nil
 }
 
-func getAccessToken() string {
+func makeIDToken() string {
+	return fmt.Sprintf("%s.%s.%s", idTokenHeader, idTokenPayload, idTokenSignature)
+}
+
+func makeAccessToken() string {
 	return fmt.Sprintf("%s.%s.%s", accessTokenHeader, accessTokenPayload, accessTokenSignature)
 }
 
 func newTestKeycloakOIDCSetup() (*httptest.Server, *KeycloakOIDCProvider) {
-	redeemURL, server := newOIDCServer([]byte(fmt.Sprintf(`{"email": "new@thing.com", "expires_in": 300, "access_token": "%v"}`, getAccessToken())))
+	redeemURL, server := newOIDCServer([]byte(fmt.Sprintf(`{"email": "new@thing.com", "expires_in": 300, "id_token": "%v", "access_token": "%v"}`, makeIDToken(), makeAccessToken())))
 	provider := newKeycloakOIDCProvider(redeemURL, options.Provider{})
 	return server, provider
 }
@@ -134,16 +147,16 @@ var _ = Describe("Keycloak OIDC Provider Tests", func() {
 				User:         "already",
 				Email:        "a@b.com",
 				Groups:       nil,
-				IDToken:      idToken,
+				IDToken:      makeIDToken(),
-				AccessToken:  getAccessToken(),
+				AccessToken:  makeAccessToken(),
 				RefreshToken: refreshToken,
 			}
 			expectedSession := &sessions.SessionState{
 				User:         "already",
 				Email:        "a@b.com",
 				Groups:       []string{"role:write", "role:default:read"},
-				IDToken:      idToken,
+				IDToken:      makeIDToken(),
-				AccessToken:  getAccessToken(),
+				AccessToken:  makeAccessToken(),
 				RefreshToken: refreshToken,
 			}
 
@@ -164,16 +177,16 @@ var _ = Describe("Keycloak OIDC Provider Tests", func() {
 				User:         "already",
 				Email:        "a@b.com",
 				Groups:       []string{"existing", "group"},
-				IDToken:      idToken,
+				IDToken:      makeIDToken(),
-				AccessToken:  getAccessToken(),
+				AccessToken:  makeAccessToken(),
 				RefreshToken: refreshToken,
 			}
 			expectedSession := &sessions.SessionState{
 				User:         "already",
 				Email:        "a@b.com",
 				Groups:       []string{"existing", "group", "role:write", "role:default:read"},
-				IDToken:      idToken,
+				IDToken:      makeIDToken(),
-				AccessToken:  getAccessToken(),
+				AccessToken:  makeAccessToken(),
 				RefreshToken: refreshToken,
 			}
 
@@ -196,8 +209,8 @@ var _ = Describe("Keycloak OIDC Provider Tests", func() {
 				User:         "already",
 				Email:        "a@b.com",
 				Groups:       nil,
-				IDToken:      idToken,
+				IDToken:      makeIDToken(),
-				AccessToken:  getAccessToken(),
+				AccessToken:  makeAccessToken(),
 				RefreshToken: refreshToken,
 			}
 
@@ -219,7 +232,7 @@ var _ = Describe("Keycloak OIDC Provider Tests", func() {
 
 			provider.ProfileURL = url
 
-			session, err := provider.CreateSessionFromToken(context.Background(), getAccessToken())
+			session, err := provider.CreateSessionFromToken(context.Background(), makeAccessToken())
 			Expect(err).To(BeNil())
 			Expect(session.ExpiresOn).ToNot(BeNil())
 			Expect(session.CreatedAt).ToNot(BeNil())