fix: endless redirection loop between /user/settings/change_password and /user/settings/security (#10002)

Fixes forgejo/forgejo#9980

## Checklist

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### Tests

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Bug fixes
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/10002): <!--number 10002 --><!--line 0 --><!--description ZW5kbGVzcyByZWRpcmVjdGlvbiBsb29wIGJldHdlZW4gL3VzZXIvc2V0dGluZ3MvY2hhbmdlX3Bhc3N3b3JkIGFuZCAvdXNlci9zZXR0aW5ncy9zZWN1cml0eQ==-->endless redirection loop between /user/settings/change_password and /user/settings/security<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10002
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.codeberg.org>
Co-authored-by: zokki <zokki.softwareschmiede@gmail.com>
Co-committed-by: zokki <zokki.softwareschmiede@gmail.com>
(cherry picked from commit dc0a63efe2)

models/fixtures/TestTwoFactorWithPasswordChange/user.yml

@@ -0,0 +1,37 @@
+-
+  id: 2001
+  lower_name: user2001
+  name: user2001
+  full_name: "user2001"
+  email: user2001@example.com
+  keep_email_private: false
+  email_notifications_preference: onmention
+  passwd: ZogKvWdyEx:password
+  passwd_hash_algo: dummy
+  must_change_password: true
+  login_source: 0
+  login_name: user2001
+  type: 0
+  salt: ZogKvWdyEx
+  max_repo_creation: -1
+  is_active: true
+  is_admin: false
+  is_restricted: false
+  allow_git_hook: false
+  allow_import_local: false
+  allow_create_organization: true
+  prohibit_login: false
+  avatar: ""
+  avatar_email: user2001@example.com
+  use_custom_avatar: true
+  num_followers: 0
+  num_following: 0
+  num_stars: 0
+  num_repos: 0
+  num_teams: 0
+  num_members: 0
+  visibility: 0
+  repo_admin_change_team_access: false
+  theme: ""
+  keep_activity_private: false
+  created_unix: 1759086716

routers/web/web.go

@@ -167,12 +167,14 @@ func verifyAuthWithOptions(options *common.VerifyOptions) func(ctx *context.Cont
 					return
 				}
 			} else if ctx.Req.URL.Path == "/user/settings/change_password" {
+				if ctx.Doer.MustHaveTwoFactor() {
+					ctx.Redirect(setting.AppSubURL + "/user/settings/security")
+					return
+				}
 				// make sure that the form cannot be accessed by users who don't need this
 				ctx.Redirect(setting.AppSubURL + "/")
 				return
-			}
-
-			if ctx.Doer.MustHaveTwoFactor() && !strings.HasPrefix(ctx.Req.URL.Path, "/user/settings/security") {
+			} else if ctx.Doer.MustHaveTwoFactor() && !strings.HasPrefix(ctx.Req.URL.Path, "/user/settings/security") {
 				hasTwoFactor, err := auth_model.HasTwoFactorByUID(ctx, ctx.Doer.ID)
 				if err != nil {
 					log.Error("Error getting 2fa: %s", err)

tests/integration/signin_test.go

@@ -17,6 +17,7 @@ import (
 	"forgejo.org/modules/setting"
 	"forgejo.org/modules/test"
 	"forgejo.org/modules/translation"
+	"forgejo.org/services/forms"
 	"forgejo.org/tests"
 
 	"github.com/stretchr/testify/assert"
@@ -276,3 +277,64 @@ func TestGlobalTwoFactorRequirement(t *testing.T) {
 		})
 	})
 }
+
+func TestTwoFactorWithPasswordChange(t *testing.T) {
+	defer unittest.OverrideFixtures("models/fixtures/TestTwoFactorWithPasswordChange")()
+
+	normalUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 4})
+	changePasswordUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{MustChangePassword: true})
+
+	runTest := func(t *testing.T, user *user_model.User, requireTOTP bool) {
+		t.Helper()
+		defer unittest.AssertSuccessfulDelete(t, &auth.TwoFactor{UID: user.ID})
+
+		session := loginUser(t, user.Name)
+
+		if user.MustChangePassword {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s", user.Name))
+			resp := session.MakeRequest(t, req, http.StatusSeeOther)
+			assert.Equal(t, "/user/settings/change_password", resp.Header().Get("Location"))
+
+			req = NewRequest(t, "GET", "/user/settings/security")
+			resp = session.MakeRequest(t, req, http.StatusSeeOther)
+			assert.Equal(t, "/user/settings/change_password", resp.Header().Get("Location"))
+
+			req = NewRequestWithJSON(t, "POST", "/user/settings/change_password", forms.MustChangePasswordForm{
+				Password: "password",
+				Retype:   "password",
+			})
+			resp = session.MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "/user/settings/security", resp.Header().Get("Location"))
+		}
+
+		if requireTOTP {
+			req := NewRequest(t, "GET", fmt.Sprintf("/%s", user.Name))
+			resp := session.MakeRequest(t, req, http.StatusSeeOther)
+			assert.Equal(t, "/user/settings/security", resp.Header().Get("Location"))
+
+			req = NewRequest(t, "GET", "/user/settings/change_password")
+			resp = session.MakeRequest(t, req, http.StatusSeeOther)
+			assert.Equal(t, "/user/settings/security", resp.Header().Get("Location"))
+
+			session.EnrollTOTP(t)
+		}
+
+		req := NewRequest(t, "GET", fmt.Sprintf("/%s", user.Name))
+		session.MakeRequest(t, req, http.StatusOK)
+	}
+
+	t.Run("Don't require TwoFactor", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		runTest(t, normalUser, false)
+		runTest(t, changePasswordUser, false)
+	})
+
+	t.Run("Require TwoFactor", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		defer test.MockVariableValue(&setting.GlobalTwoFactorRequirement, setting.AllTwoFactorRequirement)()
+
+		runTest(t, normalUser, true)
+		runTest(t, changePasswordUser, true)
+	})
+}