Always load or generate oauth2 jwt secret (#30942)

Fix #30923

(cherry picked from commit effb405cae88474c27f5c8322a2627019af1cf64)
Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>

Conflicts:
	- modules/setting/oauth2.go
	  Conflicted due to different ways of logging. Since the log
	  message is removed anyway, resolved by removing it.
	- modules/setting/oauth2_test.go
	  Manually copied the test added by Gitea.
	- routers/install/install.go
	  Not a conflict per se, but adjusted to use NewJwtSecret().

modules/setting/oauth2.go

@@ -124,16 +124,15 @@ func loadOAuth2From(rootCfg ConfigProvider) {
 		OAuth2.Enabled = sec.Key("ENABLE").MustBool(OAuth2.Enabled)
 	}
 
-	if !OAuth2.Enabled {
-		return
-	}
-
-	jwtSecretBase64 := loadSecret(sec, "JWT_SECRET_URI", "JWT_SECRET")
-
 	if !filepath.IsAbs(OAuth2.JWTSigningPrivateKeyFile) {
 		OAuth2.JWTSigningPrivateKeyFile = filepath.Join(AppDataPath, OAuth2.JWTSigningPrivateKeyFile)
 	}
 
+	// FIXME: at the moment, no matter oauth2 is enabled or not, it must generate a "oauth2 JWT_SECRET"
+	// Because this secret is also used as GeneralTokenSigningSecret (as a quick not-that-breaking fix for some legacy problems).
+	// Including: CSRF token, account validation token, etc ...
+	// In main branch, the signing token should be refactored (eg: one unique for LFS/OAuth2/etc ...)
+	jwtSecretBase64 := loadSecret(sec, "JWT_SECRET_URI", "JWT_SECRET")
 	if InstallLock {
 		jwtSecretBytes, err := generate.DecodeJwtSecret(jwtSecretBase64)
 		if err != nil {
@@ -155,8 +154,6 @@ func loadOAuth2From(rootCfg ConfigProvider) {
 	}
 }
 
-// generalSigningSecret is used as container for a []byte value
-// instead of an additional mutex, we use CompareAndSwap func to change the value thread save
 var generalSigningSecret atomic.Pointer[[]byte]
 
 func GetGeneralTokenSigningSecret() []byte {
@@ -164,11 +161,9 @@ func GetGeneralTokenSigningSecret() []byte {
 	if old == nil || len(*old) == 0 {
 		jwtSecret, _, err := generate.NewJwtSecret()
 		if err != nil {
-			log.Fatal("Unable to generate general JWT secret: %s", err.Error())
+			log.Fatal("Unable to generate general JWT secret: %v", err)
 		}
 		if generalSigningSecret.CompareAndSwap(old, &jwtSecret) {
-			// FIXME: in main branch, the signing token should be refactored (eg: one unique for LFS/OAuth2/etc ...)
-			log.Warn("OAuth2 is not enabled, unable to use a persistent signing secret, a new one is generated, which is not persistent between restarts and cluster nodes")
 			return jwtSecret
 		}
 		return *generalSigningSecret.Load()

modules/setting/oauth2_test.go

@@ -4,6 +4,7 @@
 package setting
 
 import (
+	"os"
 	"testing"
 
 	"code.gitea.io/gitea/modules/generate"
@@ -14,7 +15,7 @@ import (
 
 func TestGetGeneralSigningSecret(t *testing.T) {
 	// when there is no general signing secret, it should be generated, and keep the same value
-	assert.Nil(t, generalSigningSecret.Load())
+	generalSigningSecret.Store(nil)
 	s1 := GetGeneralTokenSigningSecret()
 	assert.NotNil(t, s1)
 	s2 := GetGeneralTokenSigningSecret()
@@ -32,3 +33,28 @@ JWT_SECRET = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
 	assert.Len(t, actual, 32)
 	assert.EqualValues(t, expected, actual)
 }
+
+func TestGetGeneralSigningSecretSave(t *testing.T) {
+	defer test.MockVariableValue(&InstallLock, true)()
+
+	old := GetGeneralTokenSigningSecret()
+	assert.Len(t, old, 32)
+
+	tmpFile := t.TempDir() + "/app.ini"
+	_ = os.WriteFile(tmpFile, nil, 0o644)
+	cfg, _ := NewConfigProviderFromFile(tmpFile)
+	loadOAuth2From(cfg)
+	generated := GetGeneralTokenSigningSecret()
+	assert.Len(t, generated, 32)
+	assert.NotEqual(t, old, generated)
+
+	generalSigningSecret.Store(nil)
+	cfg, _ = NewConfigProviderFromFile(tmpFile)
+	loadOAuth2From(cfg)
+	again := GetGeneralTokenSigningSecret()
+	assert.Equal(t, generated, again)
+
+	iniContent, err := os.ReadFile(tmpFile)
+	assert.NoError(t, err)
+	assert.Contains(t, string(iniContent), "JWT_SECRET = ")
+}

routers/install/install.go

@@ -486,6 +486,17 @@ func SubmitInstall(ctx *context.Context) {
 		cfg.Section("security").Key("INTERNAL_TOKEN").SetValue(internalToken)
 	}
 
+	// FIXME: at the moment, no matter oauth2 is enabled or not, it must generate a "oauth2 JWT_SECRET"
+	// see the "loadOAuth2From" in "setting/oauth2.go"
+	if !cfg.Section("oauth2").HasKey("JWT_SECRET") && !cfg.Section("oauth2").HasKey("JWT_SECRET_URI") {
+		_, jwtSecretBase64, err := generate.NewJwtSecret()
+		if err != nil {
+			ctx.RenderWithErr(ctx.Tr("install.secret_key_failed", err), tplInstall, &form)
+			return
+		}
+		cfg.Section("oauth2").Key("JWT_SECRET").SetValue(jwtSecretBase64)
+	}
+
 	// if there is already a SECRET_KEY, we should not overwrite it, otherwise the encrypted data will not be able to be decrypted
 	if setting.SecretKey == "" {
 		var secretKey string