Fix: Match token login name by UID or e-mail address

lib/private/User/Session.php

@@ -780,12 +780,15 @@ private function validateToken($token, $user = null) {
 	 * Check if login names match
 	 */
 	private function validateTokenLoginName(?string $loginName, IToken $token): bool {
-		if ($token->getLoginName() !== $loginName) {
-			// TODO: this makes it impossible to use different login names on browser and client
-			// e.g. login by e-mail '[email protected]' on browser for generating the token will not
-			//      allow to use the client token with the login name 'user'.
+		$tokenUser = $this->manager->get($token->getUID());
+		if (!is_null($tokenUser)) {
+			$tokenEmail = $tokenUser->getEMailAddress();
+		}
+
+		if ($token->getLoginName() !== $loginName && (is_null($tokenUser) || $tokenEmail !== $loginName)) {
 			$this->logger->error('App token login name does not match', [
 				'tokenLoginName' => $token->getLoginName(),
+				'tokenEmailAddress' => $tokenEmail,
 				'sessionLoginName' => $loginName,
 				'app' => 'core',
 				'user' => $token->getUID(),

tests/lib/User/SessionTest.php

@@ -516,6 +516,45 @@ public function testLogClientInWithTokenPassword(): void {
 		$this->assertTrue($userSession->logClientIn('john', 'I-AM-AN-APP-PASSWORD', $request, $this->throttler));
 	}
 
+	public function testLogClientInWithEmailTokenPassword(): void {
+		$manager = $this->createMock(Manager::class);
+		$session = $this->createMock(ISession::class);
+		$request = $this->createMock(IRequest::class);
+
+		/** @var Session $userSession */
+		$userSession = $this->getMockBuilder(Session::class)
+			->setConstructorArgs([$manager, $session, $this->timeFactory, $this->tokenProvider, $this->config, $this->random, $this->lockdownManager, $this->logger, $this->dispatcher])
+			->setMethods(['isTokenPassword', 'login', 'supportsCookies', 'createSessionToken', 'getUser'])
+			->getMock();
+
+		$user = $this->createMock(IUser::class);
+		$user
+			->method('getUID')
+			->willReturn('john');
+		$user
+			->method('getEMailAddress')
+			->willReturn('[email protected]');
+		$manager
+			->method('get')
+			->with('john')
+			->willReturn($user);
+		$userSession->expects($this->once())
+			->method('isTokenPassword')
+			->willReturn(true);
+		$userSession->expects($this->once())
+			->method('login')
+			->with('[email protected]')
+			->willReturn(false);
+		$token = new PublicKeyToken();
+		$token->setLoginName('john');
+		$token->setUid('john');
+		$this->tokenProvider
+			->method('getToken')
+			->with('I-AM-AN-APP-PASSWORD')
+			->willReturn($token);
+
+		$this->assertTrue($userSession->logClientIn('[email protected]', 'I-AM-AN-APP-PASSWORD', $request, $this->throttler));
+	}
 
 	public function testLogClientInNoTokenPasswordNo2fa(): void {
 		$this->expectException(PasswordLoginForbiddenException::class);