AuthN: Set uid during authentication (#87797)

* Identity: Remove GetNamespacedUID and use GetUID instead

* Authn: Set uid for users and service accounts

pkg/services/authn/authnimpl/sync/user_sync.go

@@ -364,7 +364,7 @@ func (s *UserSync) lookupByOneOf(ctx context.Context, params login.UserLookupPar
 	var err error
 
 	// If not found, try to find the user by email address
-	if usr == nil && params.Email != nil && *params.Email != "" {
+	if params.Email != nil && *params.Email != "" {
 		usr, err = s.userService.GetByEmail(ctx, &user.GetUserByEmailQuery{Email: *params.Email})
 		if err != nil && !errors.Is(err, user.ErrUserNotFound) {
 			return nil, err
@@ -390,6 +390,7 @@ func (s *UserSync) lookupByOneOf(ctx context.Context, params login.UserLookupPar
 // This is used to update the identity with the latest user information.
 func syncUserToIdentity(usr *user.User, id *authn.Identity) {
 	id.ID = authn.NewNamespaceID(authn.NamespaceUser, usr.ID)
+	id.UID = authn.NewNamespaceIDString(authn.NamespaceUser, usr.UID)
 	id.Login = usr.Login
 	id.Email = usr.Email
 	id.Name = usr.Name
@@ -399,6 +400,14 @@ func syncUserToIdentity(usr *user.User, id *authn.Identity) {
 
 // syncSignedInUserToIdentity syncs a user to an identity.
 func syncSignedInUserToIdentity(usr *user.SignedInUser, identity *authn.Identity) {
+	var ns authn.Namespace
+	if identity.ID.IsNamespace(authn.NamespaceServiceAccount) {
+		ns = authn.NamespaceServiceAccount
+	} else {
+		ns = authn.NamespaceUser
+	}
+	identity.UID = authn.NewNamespaceIDString(ns, usr.UserUID)
+
 	identity.Name = usr.Name
 	identity.Login = usr.Login
 	identity.Email = usr.Email