fix: do permission check for repository redirect

models/repo/redirect.go

@@ -14,8 +14,9 @@ import (
 
 // ErrRedirectNotExist represents a "RedirectNotExist" kind of error.
 type ErrRedirectNotExist struct {
-	OwnerID  int64
+	OwnerID           int64
-	RepoName string
+	RepoName          string
+	MissingPermission bool
 }
 
 // IsErrRedirectNotExist check if an error is an ErrRepoRedirectNotExist.
@@ -49,8 +50,8 @@ func init() {
 	db.RegisterModel(new(Redirect))
 }
 
-// LookupRedirect look up if a repository has a redirect name
+// GetRedirect returns the redirect for a given pair of ownerID and repository name.
-func LookupRedirect(ctx context.Context, ownerID int64, repoName string) (int64, error) {
+func GetRedirect(ctx context.Context, ownerID int64, repoName string) (int64, error) {
 	repoName = strings.ToLower(repoName)
 	redirect := &Redirect{OwnerID: ownerID, LowerName: repoName}
 	if has, err := db.GetEngine(ctx).Get(redirect); err != nil {

models/repo/redirect_test.go

@@ -10,21 +10,9 @@ import (
 	repo_model "forgejo.org/models/repo"
 	"forgejo.org/models/unittest"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func TestLookupRedirect(t *testing.T) {
-	require.NoError(t, unittest.PrepareTestDatabase())
-
-	repoID, err := repo_model.LookupRedirect(db.DefaultContext, 2, "oldrepo1")
-	require.NoError(t, err)
-	assert.EqualValues(t, 1, repoID)
-
-	_, err = repo_model.LookupRedirect(db.DefaultContext, unittest.NonexistentID, "doesnotexist")
-	assert.True(t, repo_model.IsErrRedirectNotExist(err))
-}
-
 func TestNewRedirect(t *testing.T) {
 	// redirect to a completely new name
 	require.NoError(t, unittest.PrepareTestDatabase())

routers/api/v1/api.go

@@ -174,7 +174,7 @@ func repoAssignment() func(ctx *context.APIContext) {
 		repo, err := repo_model.GetRepositoryByName(ctx, owner.ID, repoName)
 		if err != nil {
 			if repo_model.IsErrRepoNotExist(err) {
-				redirectRepoID, err := repo_model.LookupRedirect(ctx, owner.ID, repoName)
+				redirectRepoID, err := redirect_service.LookupRepoRedirect(ctx, ctx.Doer, owner.ID, repoName)
 				if err == nil {
 					context.RedirectToRepo(ctx.Base, redirectRepoID)
 				} else if repo_model.IsErrRedirectNotExist(err) {

routers/web/repo/githttp.go

@@ -31,6 +31,7 @@ import (
 	"forgejo.org/modules/structs"
 	"forgejo.org/modules/util"
 	"forgejo.org/services/context"
+	redirect_service "forgejo.org/services/redirect"
 	repo_service "forgejo.org/services/repository"
 
 	"github.com/go-chi/cors"
@@ -111,7 +112,7 @@ func httpBase(ctx *context.Context) *serviceHandler {
 			return nil
 		}
 
-		if redirectRepoID, err := repo_model.LookupRedirect(ctx, owner.ID, reponame); err == nil {
+		if redirectRepoID, err := redirect_service.LookupRepoRedirect(ctx, ctx.Doer, owner.ID, reponame); err == nil {
 			context.RedirectToRepo(ctx.Base, redirectRepoID)
 			return nil
 		}

services/context/repo.go

@@ -520,7 +520,7 @@ func RepoAssignment(ctx *Context) context.CancelFunc {
 	repo, err := repo_model.GetRepositoryByName(ctx, owner.ID, repoName)
 	if err != nil {
 		if repo_model.IsErrRepoNotExist(err) {
-			redirectRepoID, err := repo_model.LookupRedirect(ctx, owner.ID, repoName)
+			redirectRepoID, err := redirect_service.LookupRepoRedirect(ctx, ctx.Doer, owner.ID, repoName)
 			if err == nil {
 				RedirectToRepo(ctx.Base, redirectRepoID)
 			} else if repo_model.IsErrRedirectNotExist(err) {

services/redirect/repo.go

@@ -0,0 +1,37 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+package redirect
+
+import (
+	"context"
+
+	access_model "forgejo.org/models/perm/access"
+	repo_model "forgejo.org/models/repo"
+	user_model "forgejo.org/models/user"
+)
+
+// LookupRepoRedirect returns the repository ID if there's a redirect registered for
+// the ownerID repository name pair. It checks if the doer has permission to view
+// the new repository.
+func LookupRepoRedirect(ctx context.Context, doer *user_model.User, ownerID int64, repoName string) (int64, error) {
+	redirectID, err := repo_model.GetRedirect(ctx, ownerID, repoName)
+	if err != nil {
+		return 0, err
+	}
+
+	redirectRepo, err := repo_model.GetRepositoryByID(ctx, redirectID)
+	if err != nil {
+		return 0, err
+	}
+
+	perm, err := access_model.GetUserRepoPermission(ctx, redirectRepo, doer)
+	if err != nil {
+		return 0, err
+	}
+
+	if !perm.HasAccess() {
+		return 0, repo_model.ErrRedirectNotExist{OwnerID: ownerID, RepoName: repoName, MissingPermission: true}
+	}
+
+	return redirectID, nil
+}