Enforce two-factor auth (2FA: TOTP or WebAuthn) (#34187)

Fix #880

Design:

1. A global setting `security.TWO_FACTOR_AUTH`.
* To support org-level config, we need to introduce a better "owner
setting" system first (in the future)
2. A user without 2FA can login and may explore, but can NOT read or
write to any repositories via API/web.
3. Keep things as simple as possible.
* This option only aggressively suggest users to enable their 2FA at the
moment, it does NOT guarantee that users must have 2FA before all other
operations, it should be good enough for real world use cases.
* Some details and tests could be improved in the future since this
change only adds a check and seems won't affect too much.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

models/auth/source.go

@@ -58,6 +58,15 @@ var Names = map[Type]string{
 // Config represents login config as far as the db is concerned
 type Config interface {
 	convert.Conversion
+	SetAuthSource(*Source)
+}
+
+type ConfigBase struct {
+	AuthSource *Source
+}
+
+func (p *ConfigBase) SetAuthSource(s *Source) {
+	p.AuthSource = s
 }
 
 // SkipVerifiable configurations provide a IsSkipVerify to check if SkipVerify is set
@@ -104,19 +113,15 @@ func RegisterTypeConfig(typ Type, exemplar Config) {
 	}
 }
 
-// SourceSettable configurations can have their authSource set on them
-type SourceSettable interface {
-	SetAuthSource(*Source)
-}
-
 // Source represents an external way for authorizing users.
 type Source struct {
-	ID            int64 `xorm:"pk autoincr"`
-	Type          Type
-	Name          string             `xorm:"UNIQUE"`
-	IsActive      bool               `xorm:"INDEX NOT NULL DEFAULT false"`
-	IsSyncEnabled bool               `xorm:"INDEX NOT NULL DEFAULT false"`
-	Cfg           convert.Conversion `xorm:"TEXT"`
+	ID              int64 `xorm:"pk autoincr"`
+	Type            Type
+	Name            string `xorm:"UNIQUE"`
+	IsActive        bool   `xorm:"INDEX NOT NULL DEFAULT false"`
+	IsSyncEnabled   bool   `xorm:"INDEX NOT NULL DEFAULT false"`
+	TwoFactorPolicy string `xorm:"two_factor_policy NOT NULL DEFAULT ''"`
+	Cfg             Config `xorm:"TEXT"`
 
 	CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
 	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
@@ -140,9 +145,7 @@ func (source *Source) BeforeSet(colName string, val xorm.Cell) {
 			return
 		}
 		source.Cfg = constructor()
-		if settable, ok := source.Cfg.(SourceSettable); ok {
-			settable.SetAuthSource(source)
-		}
+		source.Cfg.SetAuthSource(source)
 	}
 }
 
@@ -200,6 +203,10 @@ func (source *Source) SkipVerify() bool {
 	return ok && skipVerifiable.IsSkipVerify()
 }
 
+func (source *Source) TwoFactorShouldSkip() bool {
+	return source.TwoFactorPolicy == "skip"
+}
+
 // CreateSource inserts a AuthSource in the DB if not already
 // existing with the given name.
 func CreateSource(ctx context.Context, source *Source) error {
@@ -223,9 +230,7 @@ func CreateSource(ctx context.Context, source *Source) error {
 		return nil
 	}
 
-	if settable, ok := source.Cfg.(SourceSettable); ok {
-		settable.SetAuthSource(source)
-	}
+	source.Cfg.SetAuthSource(source)
 
 	registerableSource, ok := source.Cfg.(RegisterableSource)
 	if !ok {
@@ -320,9 +325,7 @@ func UpdateSource(ctx context.Context, source *Source) error {
 		return nil
 	}
 
-	if settable, ok := source.Cfg.(SourceSettable); ok {
-		settable.SetAuthSource(source)
-	}
+	source.Cfg.SetAuthSource(source)
 
 	registerableSource, ok := source.Cfg.(RegisterableSource)
 	if !ok {

models/auth/source_test.go

@@ -19,6 +19,8 @@ import (
 )
 
 type TestSource struct {
+	auth_model.ConfigBase
+
 	Provider                      string
 	ClientID                      string
 	ClientSecret                  string

models/auth/twofactor.go

@@ -164,3 +164,13 @@ func DeleteTwoFactorByID(ctx context.Context, id, userID int64) error {
 	}
 	return nil
 }
+
+func HasTwoFactorOrWebAuthn(ctx context.Context, id int64) (bool, error) {
+	has, err := HasTwoFactorByUID(ctx, id)
+	if err != nil {
+		return false, err
+	} else if has {
+		return true, nil
+	}
+	return HasWebAuthnRegistrationsByUID(ctx, id)
+}

models/migrations/migrations.go

@@ -381,6 +381,7 @@ func prepareMigrationTasks() []*migration {
 		newMigration(317, "Add new index for action for heatmap", v1_24.AddNewIndexForUserDashboard),
 		newMigration(318, "Add anonymous_access_mode for repo_unit", v1_24.AddRepoUnitAnonymousAccessMode),
 		newMigration(319, "Add ExclusiveOrder to Label table", v1_24.AddExclusiveOrderColumnToLabelTable),
+		newMigration(320, "Migrate two_factor_policy to login_source table", v1_24.MigrateSkipTwoFactor),
 	}
 	return preparedMigrations
 }

models/migrations/v1_24/v320.go

@@ -0,0 +1,57 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_24 //nolint
+
+import (
+	"code.gitea.io/gitea/modules/json"
+
+	"xorm.io/xorm"
+)
+
+func MigrateSkipTwoFactor(x *xorm.Engine) error {
+	type LoginSource struct {
+		TwoFactorPolicy string `xorm:"two_factor_policy NOT NULL DEFAULT ''"`
+	}
+	_, err := x.SyncWithOptions(
+		xorm.SyncOptions{
+			IgnoreConstrains: true,
+			IgnoreIndices:    true,
+		},
+		new(LoginSource),
+	)
+	if err != nil {
+		return err
+	}
+
+	type LoginSourceSimple struct {
+		ID  int64
+		Cfg string
+	}
+
+	var loginSources []LoginSourceSimple
+	err = x.Table("login_source").Find(&loginSources)
+	if err != nil {
+		return err
+	}
+
+	for _, source := range loginSources {
+		if source.Cfg == "" {
+			continue
+		}
+
+		var cfg map[string]any
+		err = json.Unmarshal([]byte(source.Cfg), &cfg)
+		if err != nil {
+			return err
+		}
+
+		if cfg["SkipLocalTwoFA"] == true {
+			_, err = x.Exec("UPDATE login_source SET two_factor_policy = 'skip' WHERE id = ?", source.ID)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}

models/perm/access/repo_permission.go

@@ -522,3 +522,7 @@ func CheckRepoUnitUser(ctx context.Context, repo *repo_model.Repository, user *u
 
 	return perm.CanRead(unitType)
 }
+
+func PermissionNoAccess() Permission {
+	return Permission{AccessMode: perm_model.AccessModeNone}
+}