[SECURITY] Notify users about account security changes

- Currently if the password, primary mail, TOTP or security keys are
changed, no notification is made of that and makes compromising an
account a bit easier as it's essentially undetectable until the original
person tries to log in. Although other changes should be made as
well (re-authing before allowing a password change), this should go a
long way of improving the account security in Forgejo.
- Adds a mail notification for password and primary mail changes. For
the primary mail change, a mail notification is sent to the old primary
mail.
- Add a mail notification when TOTP or a security keys is removed, if no
other 2FA method is configured the mail will also contain that 2FA is
no longer needed to log into their account.
- `MakeEmailAddressPrimary` is refactored to the user service package,
as it now involves calling the mailer service.
- Unit tests added.
- Integration tests added.

services/mailer/mail.go

@@ -17,6 +17,7 @@ import (
 	"time"
 
 	activities_model "code.gitea.io/gitea/models/activities"
+	auth_model "code.gitea.io/gitea/models/auth"
 	issues_model "code.gitea.io/gitea/models/issues"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
@@ -35,10 +36,14 @@ import (
 )
 
 const (
-	mailAuthActivate       base.TplName = "auth/activate"
-	mailAuthActivateEmail  base.TplName = "auth/activate_email"
-	mailAuthResetPassword  base.TplName = "auth/reset_passwd"
-	mailAuthRegisterNotify base.TplName = "auth/register_notify"
+	mailAuthActivate           base.TplName = "auth/activate"
+	mailAuthActivateEmail      base.TplName = "auth/activate_email"
+	mailAuthResetPassword      base.TplName = "auth/reset_passwd"
+	mailAuthRegisterNotify     base.TplName = "auth/register_notify"
+	mailAuthPasswordChange     base.TplName = "auth/password_change"
+	mailAuthPrimaryMailChange  base.TplName = "auth/primary_mail_change"
+	mailAuth2faDisabled        base.TplName = "auth/2fa_disabled"
+	mailAuthRemovedSecurityKey base.TplName = "auth/removed_security_key"
 
 	mailNotifyCollaborator base.TplName = "notify/collaborator"
 
@@ -561,3 +566,133 @@ func fromDisplayName(u *user_model.User) string {
 	}
 	return u.GetCompleteName()
 }
+
+// SendPasswordChange informs the user on their primary email address that
+// their password was changed.
+func SendPasswordChange(u *user_model.User) error {
+	if setting.MailService == nil {
+		return nil
+	}
+	locale := translation.NewLocale(u.Language)
+
+	data := map[string]any{
+		"locale":      locale,
+		"DisplayName": u.DisplayName(),
+		"Username":    u.Name,
+		"Language":    locale.Language(),
+	}
+
+	var content bytes.Buffer
+
+	if err := bodyTemplates.ExecuteTemplate(&content, string(mailAuthPasswordChange), data); err != nil {
+		return err
+	}
+
+	msg := NewMessage(u.EmailTo(), locale.TrString("mail.password_change.subject"), content.String())
+	msg.Info = fmt.Sprintf("UID: %d, password change notification", u.ID)
+
+	SendAsync(msg)
+	return nil
+}
+
+// SendPrimaryMailChange informs the user on their old primary email address
+// that it's no longer used as primary mail and will no longer receive
+// notification on that email address.
+func SendPrimaryMailChange(u *user_model.User, oldPrimaryEmail string) error {
+	if setting.MailService == nil {
+		return nil
+	}
+	locale := translation.NewLocale(u.Language)
+
+	data := map[string]any{
+		"locale":         locale,
+		"NewPrimaryMail": u.Email,
+		"DisplayName":    u.DisplayName(),
+		"Username":       u.Name,
+		"Language":       locale.Language(),
+	}
+
+	var content bytes.Buffer
+
+	if err := bodyTemplates.ExecuteTemplate(&content, string(mailAuthPrimaryMailChange), data); err != nil {
+		return err
+	}
+
+	msg := NewMessage(u.EmailTo(oldPrimaryEmail), locale.TrString("mail.primary_mail_change.subject"), content.String())
+	msg.Info = fmt.Sprintf("UID: %d, primary email change notification", u.ID)
+
+	SendAsync(msg)
+	return nil
+}
+
+// SendDisabledTOTP informs the user that their totp has been disabled.
+func SendDisabledTOTP(ctx context.Context, u *user_model.User) error {
+	if setting.MailService == nil {
+		return nil
+	}
+	locale := translation.NewLocale(u.Language)
+
+	hasWebAuthn, err := auth_model.HasWebAuthnRegistrationsByUID(ctx, u.ID)
+	if err != nil {
+		return err
+	}
+
+	data := map[string]any{
+		"locale":      locale,
+		"HasWebAuthn": hasWebAuthn,
+		"DisplayName": u.DisplayName(),
+		"Username":    u.Name,
+		"Language":    locale.Language(),
+	}
+
+	var content bytes.Buffer
+
+	if err := bodyTemplates.ExecuteTemplate(&content, string(mailAuth2faDisabled), data); err != nil {
+		return err
+	}
+
+	msg := NewMessage(u.EmailTo(), locale.TrString("mail.totp_disabled.subject"), content.String())
+	msg.Info = fmt.Sprintf("UID: %d, 2fa disabled notification", u.ID)
+
+	SendAsync(msg)
+	return nil
+}
+
+// SendRemovedWebAuthn informs the user that one of their security keys has been removed.
+func SendRemovedSecurityKey(ctx context.Context, u *user_model.User, securityKeyName string) error {
+	if setting.MailService == nil {
+		return nil
+	}
+	locale := translation.NewLocale(u.Language)
+
+	hasWebAuthn, err := auth_model.HasWebAuthnRegistrationsByUID(ctx, u.ID)
+	if err != nil {
+		return err
+	}
+	hasTOTP, err := auth_model.HasTwoFactorByUID(ctx, u.ID)
+	if err != nil {
+		return err
+	}
+
+	data := map[string]any{
+		"locale":          locale,
+		"HasWebAuthn":     hasWebAuthn,
+		"HasTOTP":         hasTOTP,
+		"SecurityKeyName": securityKeyName,
+		"DisplayName":     u.DisplayName(),
+		"Username":        u.Name,
+		"Language":        locale.Language(),
+	}
+
+	var content bytes.Buffer
+
+	if err := bodyTemplates.ExecuteTemplate(&content, string(mailAuthRemovedSecurityKey), data); err != nil {
+		return err
+	}
+
+	msg := NewMessage(u.EmailTo(), locale.TrString("mail.removed_security_key.subject"), content.String())
+	msg.Info = fmt.Sprintf("UID: %d, security key removed notification", u.ID)
+
+	SendAsync(msg)
+	return nil
+}

services/mailer/mail_admin_new_user_test.go

@@ -55,14 +55,14 @@ func TestAdminNotificationMail_test(t *testing.T) {
 		defer test.MockVariableValue(&setting.Admin.SendNotificationEmailOnNewUser, true)()
 
 		called := false
-		defer mockMailSettings(func(msgs ...*Message) {
+		defer MockMailSettings(func(msgs ...*Message) {
 			assert.Equal(t, len(msgs), 1, "Test provides only one admin user, so only one email must be sent")
 			assert.Equal(t, msgs[0].To, users[0].Email, "checks if the recipient is the admin of the instance")
 			manageUserURL := setting.AppURL + "admin/users/" + strconv.FormatInt(users[1].ID, 10)
 			assert.Contains(t, msgs[0].Body, manageUserURL)
 			assert.Contains(t, msgs[0].Body, users[1].HTMLURL())
 			assert.Contains(t, msgs[0].Body, users[1].Name, "user name of the newly created user")
-			assertTranslatedLocale(t, msgs[0].Body, "mail.admin", "admin.users")
+			AssertTranslatedLocale(t, msgs[0].Body, "mail.admin", "admin.users")
 			called = true
 		})()
 		MailNewUser(ctx, users[1])
@@ -71,7 +71,7 @@ func TestAdminNotificationMail_test(t *testing.T) {
 
 	t.Run("SendNotificationEmailOnNewUser_false", func(t *testing.T) {
 		defer test.MockVariableValue(&setting.Admin.SendNotificationEmailOnNewUser, false)()
-		defer mockMailSettings(func(msgs ...*Message) {
+		defer MockMailSettings(func(msgs ...*Message) {
 			assert.Equal(t, 1, 0, "this shouldn't execute. MailNewUser must exit early since SEND_NOTIFICATION_EMAIL_ON_NEW_USER is disabled")
 		})()
 		MailNewUser(ctx, users[1])

services/mailer/mail_auth_test.go

@@ -0,0 +1,60 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package mailer_test
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/optional"
+	"code.gitea.io/gitea/modules/translation"
+	"code.gitea.io/gitea/services/mailer"
+	user_service "code.gitea.io/gitea/services/user"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPasswordChangeMail(t *testing.T) {
+	defer require.NoError(t, unittest.PrepareTestDatabase())
+
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	called := false
+	defer mailer.MockMailSettings(func(msgs ...*mailer.Message) {
+		assert.Len(t, msgs, 1)
+		assert.Equal(t, user.EmailTo(), msgs[0].To)
+		assert.EqualValues(t, translation.NewLocale("en-US").Tr("mail.password_change.subject"), msgs[0].Subject)
+		mailer.AssertTranslatedLocale(t, msgs[0].Body, "mail.password_change.text_1", "mail.password_change.text_2", "mail.password_change.text_3")
+		called = true
+	})()
+
+	require.NoError(t, user_service.UpdateAuth(db.DefaultContext, user, &user_service.UpdateAuthOptions{Password: optional.Some("NewPasswordYolo!")}))
+	assert.True(t, called)
+}
+
+func TestPrimaryMailChange(t *testing.T) {
+	defer require.NoError(t, unittest.PrepareTestDatabase())
+
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	firstEmail := unittest.AssertExistsAndLoadBean(t, &user_model.EmailAddress{ID: 3, UID: user.ID, IsPrimary: true})
+	secondEmail := unittest.AssertExistsAndLoadBean(t, &user_model.EmailAddress{ID: 35, UID: user.ID}, "is_primary = false")
+
+	called := false
+	defer mailer.MockMailSettings(func(msgs ...*mailer.Message) {
+		assert.False(t, called)
+		assert.Len(t, msgs, 1)
+		assert.Equal(t, user.EmailTo(firstEmail.Email), msgs[0].To)
+		assert.EqualValues(t, translation.NewLocale("en-US").Tr("mail.primary_mail_change.subject"), msgs[0].Subject)
+		assert.Contains(t, msgs[0].Body, secondEmail.Email)
+		mailer.AssertTranslatedLocale(t, msgs[0].Body, "mail.primary_mail_change.text_1", "mail.primary_mail_change.text_2", "mail.primary_mail_change.text_3")
+		called = true
+	})()
+
+	require.NoError(t, user_service.MakeEmailAddressPrimary(db.DefaultContext, user, secondEmail, true))
+	assert.True(t, called)
+
+	require.NoError(t, user_service.MakeEmailAddressPrimary(db.DefaultContext, user, firstEmail, false))
+}

services/mailer/mail_test.go

@@ -62,7 +62,7 @@ func prepareMailerTest(t *testing.T) (doer *user_model.User, repo *repo_model.Re
 }
 
 func TestComposeIssueCommentMessage(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	doer, _, issue, comment := prepareMailerTest(t)
 
 	markup.Init(&markup.ProcessorHelper{
@@ -117,7 +117,7 @@ func TestComposeIssueCommentMessage(t *testing.T) {
 }
 
 func TestComposeIssueMessage(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	doer, _, issue, _ := prepareMailerTest(t)
 
 	recipients := []*user_model.User{{Name: "Test", Email: "test@gitea.com"}, {Name: "Test2", Email: "test2@gitea.com"}}
@@ -146,7 +146,7 @@ func TestComposeIssueMessage(t *testing.T) {
 }
 
 func TestMailerIssueTemplate(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	assert.NoError(t, unittest.PrepareTestDatabase())
 
 	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
@@ -160,7 +160,7 @@ func TestMailerIssueTemplate(t *testing.T) {
 		for _, s := range expected {
 			assert.Contains(t, wholemsg, s)
 		}
-		assertTranslatedLocale(t, wholemsg, "mail.issue")
+		AssertTranslatedLocale(t, wholemsg, "mail.issue")
 	}
 
 	testCompose := func(t *testing.T, ctx *mailCommentContext) *Message {
@@ -241,7 +241,7 @@ func TestMailerIssueTemplate(t *testing.T) {
 }
 
 func TestTemplateSelection(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	doer, repo, issue, comment := prepareMailerTest(t)
 	recipients := []*user_model.User{{Name: "Test", Email: "test@gitea.com"}}
 
@@ -296,7 +296,7 @@ func TestTemplateSelection(t *testing.T) {
 }
 
 func TestTemplateServices(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	doer, _, issue, comment := prepareMailerTest(t)
 	assert.NoError(t, issue.LoadRepo(db.DefaultContext))
 
@@ -349,7 +349,7 @@ func testComposeIssueCommentMessage(t *testing.T, ctx *mailCommentContext, recip
 }
 
 func TestGenerateAdditionalHeaders(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	doer, _, issue, _ := prepareMailerTest(t)
 
 	ctx := &mailCommentContext{Context: context.TODO() /* TODO: use a correct context */, Issue: issue, Doer: doer}
@@ -382,7 +382,7 @@ func TestGenerateAdditionalHeaders(t *testing.T) {
 }
 
 func Test_createReference(t *testing.T) {
-	defer mockMailSettings(nil)()
+	defer MockMailSettings(nil)()
 	_, _, issue, comment := prepareMailerTest(t)
 	_, _, pullIssue, _ := prepareMailerTest(t)
 	pullIssue.IsPull = true

services/mailer/main_test.go

@@ -22,14 +22,14 @@ func TestMain(m *testing.M) {
 	unittest.MainTest(m)
 }
 
-func assertTranslatedLocale(t *testing.T, message string, prefixes ...string) {
+func AssertTranslatedLocale(t *testing.T, message string, prefixes ...string) {
 	t.Helper()
 	for _, prefix := range prefixes {
 		assert.NotContains(t, message, prefix, "there is an untranslated locale prefix")
 	}
 }
 
-func mockMailSettings(send func(msgs ...*Message)) func() {
+func MockMailSettings(send func(msgs ...*Message)) func() {
 	translation.InitLocales(context.Background())
 	subjectTemplates, bodyTemplates = templates.Mailer(context.Background())
 	mailService := setting.Mailer{