fix: revoke access token on duplicate auth code user

internal/assets/migrations/000008_oidc_code_reuse.down.sql

@@ -0,0 +1 @@
+ALTER TABLE "oidc_tokens" DROP COLUMN "code_hash";

internal/assets/migrations/000008_oidc_code_reuse.up.sql

@@ -0,0 +1 @@
+ALTER TABLE "oidc_tokens" ADD COLUMN "code_hash" TEXT NOT NULL DEFAULT "";

internal/controller/oidc_controller.go

@@ -275,6 +275,9 @@ func (controller *OIDCController) Token(c *gin.Context) {
 	case "authorization_code":
 		entry, err := controller.oidc.GetCodeEntry(c, controller.oidc.Hash(req.Code), client.ClientID)
 		if err != nil {
+			if err := controller.oidc.DeleteTokenByCodeHash(c, controller.oidc.Hash(req.Code)); err != nil {
+				tlog.App.Error().Err(err).Msg("Failed to delete access token by code hash")
+			}
 			if errors.Is(err, service.ErrCodeNotFound) {
 				tlog.App.Warn().Msg("Code not found")
 				c.JSON(400, gin.H{

internal/controller/oidc_controller_test.go

@@ -387,7 +387,7 @@ func TestOIDCController(t *testing.T) {
 				err = json.Unmarshal(secondRecorder.Body.Bytes(), &secondRes)
 				assert.NoError(t, err)
 
-				assert.Equal(t, secondRes["error"], "invalid_grant")
+				assert.Equal(t, "invalid_grant", secondRes["error"])
 			},
 		},
 		{
@@ -778,6 +778,74 @@ func TestOIDCController(t *testing.T) {
 				assert.NotEmpty(t, error)
 			},
 		},
+		{
+			description: "Ensure access token gets invalidated on double code use",
+			middlewares: []gin.HandlerFunc{
+				simpleCtx,
+			},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				authorizeCodeTest, found := getTestByDescription("Ensure authorize succeeds with valid params")
+				assert.True(t, found, "Authorize test not found")
+				authorizeCodeTest(t, router, recorder)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+
+				redirectURI := res["redirect_uri"].(string)
+				url, err := url.Parse(redirectURI)
+				assert.NoError(t, err)
+
+				queryParams := url.Query()
+				code := queryParams.Get("code")
+				assert.NotEmpty(t, code)
+
+				reqBody := controller.TokenRequest{
+					GrantType:   "authorization_code",
+					Code:        code,
+					RedirectURI: "https://test.example.com/callback",
+				}
+				reqBodyEncoded, err := query.Values(reqBody)
+				assert.NoError(t, err)
+
+				req := httptest.NewRequest("POST", "/api/oidc/token", strings.NewReader(reqBodyEncoded.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				req.SetBasicAuth("some-client-id", "some-client-secret")
+				recorder = httptest.NewRecorder()
+				router.ServeHTTP(recorder, req)
+
+				assert.Equal(t, 200, recorder.Code)
+
+				err = json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+
+				accessToken := res["access_token"].(string)
+				assert.NotEmpty(t, accessToken)
+
+				req = httptest.NewRequest("GET", "/api/oidc/userinfo", nil)
+				req.Header.Set("Authorization", "Bearer "+accessToken)
+				recorder = httptest.NewRecorder()
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 200, recorder.Code)
+
+				req = httptest.NewRequest("POST", "/api/oidc/token", strings.NewReader(reqBodyEncoded.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				req.SetBasicAuth("some-client-id", "some-client-secret")
+				recorder = httptest.NewRecorder()
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 400, recorder.Code)
+
+				req = httptest.NewRequest("GET", "/api/oidc/userinfo", nil)
+				req.Header.Set("Authorization", "Bearer "+accessToken)
+				recorder = httptest.NewRecorder()
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 401, recorder.Code)
+
+				err = json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_grant", res["error"])
+			},
+		},
 	}
 
 	app := bootstrap.NewBootstrapApp(config.Config{})

internal/service/oidc_service.go

@@ -506,6 +506,7 @@ func (service *OIDCService) GenerateAccessToken(c *gin.Context, client config.OI
 		TokenExpiresAt:        tokenExpiresAt,
 		RefreshTokenExpiresAt: refrshTokenExpiresAt,
 		Nonce:                 codeEntry.Nonce,
+		CodeHash:              codeEntry.CodeHash,
 	})
 
 	if err != nil {
@@ -590,6 +591,10 @@ func (service *OIDCService) DeleteToken(c *gin.Context, tokenHash string) error
 	return service.queries.DeleteOidcToken(c, tokenHash)
 }
 
+func (service *OIDCService) DeleteTokenByCodeHash(c *gin.Context, codeHash string) error {
+	return service.queries.DeleteOidcTokenByCodeHash(c, codeHash)
+}
+
 func (service *OIDCService) GetAccessToken(c *gin.Context, tokenHash string) (repository.OidcToken, error) {
 	entry, err := service.queries.GetOidcToken(c, tokenHash)
 

sql/oidc_queries.sql

@@ -48,9 +48,10 @@ INSERT INTO "oidc_tokens" (
     "client_id",
     "token_expires_at",
     "refresh_token_expires_at",
+    "code_hash",
     "nonce"
 ) VALUES (
-    ?, ?, ?, ?, ?, ?, ?, ?
+    ?, ?, ?, ?, ?, ?, ?, ?, ?
 )
 RETURNING *;
 
@@ -75,6 +76,10 @@ WHERE "refresh_token_hash" = ?;
 SELECT * FROM "oidc_tokens"
 WHERE "sub" = ?;
 
+-- name: DeleteOidcTokenByCodeHash :exec
+DELETE FROM "oidc_tokens"
+WHERE "code_hash" = ?;
+
 -- name: DeleteOidcToken :exec
 DELETE FROM "oidc_tokens"
 WHERE "access_token_hash" = ?;

sql/oidc_schemas.sql

@@ -13,6 +13,7 @@ CREATE TABLE IF NOT EXISTS "oidc_tokens" (
     "sub" TEXT NOT NULL UNIQUE,
     "access_token_hash" TEXT NOT NULL PRIMARY KEY UNIQUE,
     "refresh_token_hash" TEXT NOT NULL,
+    "code_hash" TEXT NOT NULL,
     "scope" TEXT NOT NULL,
     "client_id" TEXT NOT NULL,
     "token_expires_at" INTEGER NOT NULL,