allow synchronizing user status from OAuth2 login providers (#31572)

This leverages the existing `sync_external_users` cron job to
synchronize the `IsActive` flag on users who use an OAuth2 provider set
to synchronize. This synchronization is done by checking for expired
access tokens, and using the stored refresh token to request a new
access token. If the response back from the OAuth2 provider is the
`invalid_grant` error code, the user is marked as inactive. However, the
user is able to reactivate their account by logging in the web browser
through their OAuth2 flow.

Also changed to support this is that a linked `ExternalLoginUser` is
always created upon a login or signup via OAuth2.

### Notes on updating permissions
Ideally, we would also refresh permissions from the configured OAuth
provider (e.g., admin, restricted and group mappings) to match the
implementation of LDAP. However, the OAuth library used for this `goth`,
doesn't seem to support issuing a session via refresh tokens. The
interface provides a [`RefreshToken`
method](https://github.com/markbates/goth/blob/master/provider.go#L20),
but the returned `oauth.Token` doesn't implement the `goth.Session` we
would need to call `FetchUser`. Due to specific implementations, we
would need to build a compatibility function for every provider, since
they cast to concrete types (e.g.
[Azure](https://github.com/markbates/goth/blob/master/providers/azureadv2/azureadv2.go#L132))

---------

Co-authored-by: Kyle D <[email protected]>

Author: bohde

models/auth/source.go

@@ -210,7 +210,7 @@ func CreateSource(ctx context.Context, source *Source) error {
 		return ErrSourceAlreadyExist{source.Name}
 	}
 	// Synchronization is only available with LDAP for now
-	if !source.IsLDAP() {
+	if !source.IsLDAP() && !source.IsOAuth2() {
 		source.IsSyncEnabled = false
 	}
 

models/user/external_login_user.go

@@ -160,12 +160,34 @@ func UpdateExternalUserByExternalID(ctx context.Context, external *ExternalLogin
 	return err
 }
 
+// EnsureLinkExternalToUser link the external user to the user
+func EnsureLinkExternalToUser(ctx context.Context, external *ExternalLoginUser) error {
+	has, err := db.Exist[ExternalLoginUser](ctx, builder.Eq{
+		"external_id":     external.ExternalID,
+		"login_source_id": external.LoginSourceID,
+	})
+	if err != nil {
+		return err
+	}
+
+	if has {
+		_, err = db.GetEngine(ctx).Where("external_id=? AND login_source_id=?", external.ExternalID, external.LoginSourceID).AllCols().Update(external)
+		return err
+	}
+
+	_, err = db.GetEngine(ctx).Insert(external)
+	return err
+}
+
 // FindExternalUserOptions represents an options to find external users
 type FindExternalUserOptions struct {
 	db.ListOptions
-	Provider string
-	UserID   int64
-	OrderBy  string
+	Provider        string
+	UserID          int64
+	LoginSourceID   int64
+	HasRefreshToken bool
+	Expired         bool
+	OrderBy         string
 }
 
 func (opts FindExternalUserOptions) ToConds() builder.Cond {
@@ -176,9 +198,22 @@ func (opts FindExternalUserOptions) ToConds() builder.Cond {
 	if opts.UserID > 0 {
 		cond = cond.And(builder.Eq{"user_id": opts.UserID})
 	}
+	if opts.Expired {
+		cond = cond.And(builder.Lt{"expires_at": time.Now()})
+	}
+	if opts.HasRefreshToken {
+		cond = cond.And(builder.Neq{"refresh_token": ""})
+	}
+	if opts.LoginSourceID != 0 {
+		cond = cond.And(builder.Eq{"login_source_id": opts.LoginSourceID})
+	}
 	return cond
 }
 
 func (opts FindExternalUserOptions) ToOrders() string {
 	return opts.OrderBy
 }
+
+func IterateExternalLogin(ctx context.Context, opts FindExternalUserOptions, f func(ctx context.Context, u *ExternalLoginUser) error) error {
+	return db.Iterate(ctx, opts.ToConds(), f)
+}

routers/web/auth/auth.go

@@ -622,10 +622,8 @@ func handleUserCreated(ctx *context.Context, u *user_model.User, gothUser *goth.
 
 	// update external user information
 	if gothUser != nil {
-		if err := externalaccount.UpdateExternalUser(ctx, u, *gothUser); err != nil {
-			if !errors.Is(err, util.ErrNotExist) {
-				log.Error("UpdateExternalUser failed: %v", err)
-			}
+		if err := externalaccount.EnsureLinkExternalToUser(ctx, u, *gothUser); err != nil {
+			log.Error("EnsureLinkExternalToUser failed: %v", err)
 		}
 	}
 

routers/web/auth/oauth.go

@@ -27,7 +27,6 @@ import (
 	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
-	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/modules/web/middleware"
 	auth_service "code.gitea.io/gitea/services/auth"
@@ -1148,9 +1147,39 @@ func handleOAuth2SignIn(ctx *context.Context, source *auth.Source, u *user_model
 
 	groups := getClaimedGroups(oauth2Source, &gothUser)
 
+	opts := &user_service.UpdateOptions{}
+
+	// Reactivate user if they are deactivated
+	if !u.IsActive {
+		opts.IsActive = optional.Some(true)
+	}
+
+	// Update GroupClaims
+	opts.IsAdmin, opts.IsRestricted = getUserAdminAndRestrictedFromGroupClaims(oauth2Source, &gothUser)
+
+	if oauth2Source.GroupTeamMap != "" || oauth2Source.GroupTeamMapRemoval {
+		if err := source_service.SyncGroupsToTeams(ctx, u, groups, groupTeamMapping, oauth2Source.GroupTeamMapRemoval); err != nil {
+			ctx.ServerError("SyncGroupsToTeams", err)
+			return
+		}
+	}
+
+	if err := externalaccount.EnsureLinkExternalToUser(ctx, u, gothUser); err != nil {
+		ctx.ServerError("EnsureLinkExternalToUser", err)
+		return
+	}
+
 	// If this user is enrolled in 2FA and this source doesn't override it,
 	// we can't sign the user in just yet. Instead, redirect them to the 2FA authentication page.
 	if !needs2FA {
+		// Register last login
+		opts.SetLastLogin = true
+
+		if err := user_service.UpdateUser(ctx, u, opts); err != nil {
+			ctx.ServerError("UpdateUser", err)
+			return
+		}
+
 		if err := updateSession(ctx, nil, map[string]any{
 			"uid":   u.ID,
 			"uname": u.Name,
@@ -1162,29 +1191,6 @@ func handleOAuth2SignIn(ctx *context.Context, source *auth.Source, u *user_model
 		// Clear whatever CSRF cookie has right now, force to generate a new one
 		ctx.Csrf.DeleteCookie(ctx)
 
-		opts := &user_service.UpdateOptions{
-			SetLastLogin: true,
-		}
-		opts.IsAdmin, opts.IsRestricted = getUserAdminAndRestrictedFromGroupClaims(oauth2Source, &gothUser)
-		if err := user_service.UpdateUser(ctx, u, opts); err != nil {
-			ctx.ServerError("UpdateUser", err)
-			return
-		}
-
-		if oauth2Source.GroupTeamMap != "" || oauth2Source.GroupTeamMapRemoval {
-			if err := source_service.SyncGroupsToTeams(ctx, u, groups, groupTeamMapping, oauth2Source.GroupTeamMapRemoval); err != nil {
-				ctx.ServerError("SyncGroupsToTeams", err)
-				return
-			}
-		}
-
-		// update external user information
-		if err := externalaccount.UpdateExternalUser(ctx, u, gothUser); err != nil {
-			if !errors.Is(err, util.ErrNotExist) {
-				log.Error("UpdateExternalUser failed: %v", err)
-			}
-		}
-
 		if err := resetLocale(ctx, u); err != nil {
 			ctx.ServerError("resetLocale", err)
 			return
@@ -1200,22 +1206,13 @@ func handleOAuth2SignIn(ctx *context.Context, source *auth.Source, u *user_model
 		return
 	}
 
-	opts := &user_service.UpdateOptions{}
-	opts.IsAdmin, opts.IsRestricted = getUserAdminAndRestrictedFromGroupClaims(oauth2Source, &gothUser)
-	if opts.IsAdmin.Has() || opts.IsRestricted.Has() {
+	if opts.IsActive.Has() || opts.IsAdmin.Has() || opts.IsRestricted.Has() {
 		if err := user_service.UpdateUser(ctx, u, opts); err != nil {
 			ctx.ServerError("UpdateUser", err)
 			return
 		}
 	}
 
-	if oauth2Source.GroupTeamMap != "" || oauth2Source.GroupTeamMapRemoval {
-		if err := source_service.SyncGroupsToTeams(ctx, u, groups, groupTeamMapping, oauth2Source.GroupTeamMapRemoval); err != nil {
-			ctx.ServerError("SyncGroupsToTeams", err)
-			return
-		}
-	}
-
 	if err := updateSession(ctx, nil, map[string]any{
 		// User needs to use 2FA, save data and redirect to 2FA page.
 		"twofaUid":      u.ID,

services/auth/source/oauth2/main_test.go

@@ -0,0 +1,14 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package oauth2
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m, &unittest.TestOptions{})
+}

services/auth/source/oauth2/providers_test.go

@@ -0,0 +1,62 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package oauth2
+
+import (
+	"time"
+
+	"github.com/markbates/goth"
+	"golang.org/x/oauth2"
+)
+
+type fakeProvider struct{}
+
+func (p *fakeProvider) Name() string {
+	return "fake"
+}
+
+func (p *fakeProvider) SetName(name string) {}
+
+func (p *fakeProvider) BeginAuth(state string) (goth.Session, error) {
+	return nil, nil
+}
+
+func (p *fakeProvider) UnmarshalSession(string) (goth.Session, error) {
+	return nil, nil
+}
+
+func (p *fakeProvider) FetchUser(goth.Session) (goth.User, error) {
+	return goth.User{}, nil
+}
+
+func (p *fakeProvider) Debug(bool) {
+}
+
+func (p *fakeProvider) RefreshToken(refreshToken string) (*oauth2.Token, error) {
+	switch refreshToken {
+	case "expired":
+		return nil, &oauth2.RetrieveError{
+			ErrorCode: "invalid_grant",
+		}
+	default:
+		return &oauth2.Token{
+			AccessToken:  "token",
+			TokenType:    "Bearer",
+			RefreshToken: "refresh",
+			Expiry:       time.Now().Add(time.Hour),
+		}, nil
+	}
+}
+
+func (p *fakeProvider) RefreshTokenAvailable() bool {
+	return true
+}
+
+func init() {
+	RegisterGothProvider(
+		NewSimpleProvider("fake", "Fake", []string{"account"},
+			func(clientKey, secret, callbackURL string, scopes ...string) goth.Provider {
+				return &fakeProvider{}
+			}))
+}

services/auth/source/oauth2/source.go

@@ -36,7 +36,7 @@ func (source *Source) FromDB(bs []byte) error {
 	return json.UnmarshalHandleDoubleEncode(bs, &source)
 }
 
-// ToDB exports an SMTPConfig to a serialized format.
+// ToDB exports an OAuth2Config to a serialized format.
 func (source *Source) ToDB() ([]byte, error) {
 	return json.Marshal(source)
 }

services/auth/source/oauth2/source_sync.go

@@ -0,0 +1,114 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package oauth2
+
+import (
+	"context"
+	"time"
+
+	"code.gitea.io/gitea/models/auth"
+	"code.gitea.io/gitea/models/db"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/log"
+
+	"github.com/markbates/goth"
+	"golang.org/x/oauth2"
+)
+
+// Sync causes this OAuth2 source to synchronize its users with the db.
+func (source *Source) Sync(ctx context.Context, updateExisting bool) error {
+	log.Trace("Doing: SyncExternalUsers[%s] %d", source.authSource.Name, source.authSource.ID)
+
+	if !updateExisting {
+		log.Info("SyncExternalUsers[%s] not running since updateExisting is false", source.authSource.Name)
+		return nil
+	}
+
+	provider, err := createProvider(source.authSource.Name, source)
+	if err != nil {
+		return err
+	}
+
+	if !provider.RefreshTokenAvailable() {
+		log.Trace("SyncExternalUsers[%s] provider doesn't support refresh tokens, can't synchronize", source.authSource.Name)
+		return nil
+	}
+
+	opts := user_model.FindExternalUserOptions{
+		HasRefreshToken: true,
+		Expired:         true,
+		LoginSourceID:   source.authSource.ID,
+	}
+
+	return user_model.IterateExternalLogin(ctx, opts, func(ctx context.Context, u *user_model.ExternalLoginUser) error {
+		return source.refresh(ctx, provider, u)
+	})
+}
+
+func (source *Source) refresh(ctx context.Context, provider goth.Provider, u *user_model.ExternalLoginUser) error {
+	log.Trace("Syncing login_source_id=%d external_id=%s expiration=%s", u.LoginSourceID, u.ExternalID, u.ExpiresAt)
+
+	shouldDisable := false
+
+	token, err := provider.RefreshToken(u.RefreshToken)
+	if err != nil {
+		if err, ok := err.(*oauth2.RetrieveError); ok && err.ErrorCode == "invalid_grant" {
+			// this signals that the token is not valid and the user should be disabled
+			shouldDisable = true
+		} else {
+			return err
+		}
+	}
+
+	user := &user_model.User{
+		LoginName:   u.ExternalID,
+		LoginType:   auth.OAuth2,
+		LoginSource: u.LoginSourceID,
+	}
+
+	hasUser, err := user_model.GetUser(ctx, user)
+	if err != nil {
+		return err
+	}
+
+	// If the grant is no longer valid, disable the user and
+	// delete local tokens. If the OAuth2 provider still
+	// recognizes them as a valid user, they will be able to login
+	// via their provider and reactivate their account.
+	if shouldDisable {
+		log.Info("SyncExternalUsers[%s] disabling user %d", source.authSource.Name, user.ID)
+
+		return db.WithTx(ctx, func(ctx context.Context) error {
+			if hasUser {
+				user.IsActive = false
+				err := user_model.UpdateUserCols(ctx, user, "is_active")
+				if err != nil {
+					return err
+				}
+			}
+
+			// Delete stored tokens, since they are invalid. This
+			// also provents us from checking this in subsequent runs.
+			u.AccessToken = ""
+			u.RefreshToken = ""
+			u.ExpiresAt = time.Time{}
+
+			return user_model.UpdateExternalUserByExternalID(ctx, u)
+		})
+	}
+
+	// Otherwise, update the tokens
+	u.AccessToken = token.AccessToken
+	u.ExpiresAt = token.Expiry
+
+	// Some providers only update access tokens provide a new
+	// refresh token, so avoid updating it if it's empty
+	if token.RefreshToken != "" {
+		u.RefreshToken = token.RefreshToken
+	}
+
+	err = user_model.UpdateExternalUserByExternalID(ctx, u)
+
+	return err
+}