From patchwork Fri May 8 09:22:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11536125 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D25C913 for ; Fri, 8 May 2020 09:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1499208DB for ; Fri, 8 May 2020 09:23:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jvP7+X5X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726746AbgEHJWb (ORCPT ); Fri, 8 May 2020 05:22:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725379AbgEHJWa (ORCPT ); Fri, 8 May 2020 05:22:30 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49B98C05BD43; Fri, 8 May 2020 02:22:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc: To:From:Sender:Reply-To:Content-ID:Content-Description; bh=w8+H/WdMyxnhfLBjBxD8TC1RnBnytabQkaUnuZkvk7I=; b=jvP7+X5X7VRIMwCYgT7LNK0AFl XUjK6E9jLYjSPhdxBhk4e8cjUgzYRdfPmgcekEHtrCLFzVPVYOmflEAT2tytuFBAuKLvPZ7vgUuHV QxZDMpCoN65mGRvFviWLQwZpYYk3P5CsK/ASiV/YnKIG47vuwlVqXAwfcZsYnDtD0k2LIT4i3cv7q ucYZnJ3na83YU8pBMu9hGVaES8VRMgpT72itohPncZ+s92Bgutanx8IQ714uW/Yfx0SDflH/R8uz6 QdXGcn6rKYt/thKQ3KxVSThheOBqc+odYus2izfMSzKAfdauHUpKYV+EI1/LJxXhiNo0WOgpTCJie heeDjR6g==; Received: from [2001:4bb8:180:9d3f:90d7:9df8:7cd:3504] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWzDB-0008J4-QF; Fri, 08 May 2020 09:22:30 +0000 From: Christoph Hellwig To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH 02/11] fs: check FMODE_WRITE in __kernel_write Date: Fri, 8 May 2020 11:22:13 +0200 Message-Id: <20200508092222.2097-3-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200508092222.2097-1-hch@lst.de> References: <20200508092222.2097-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: We still need to check if the fѕ is open write, even for the low-level helper. Signed-off-by: Christoph Hellwig --- fs/read_write.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/read_write.c b/fs/read_write.c index d5aaf3a4198b9..d5c754080e5a5 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -505,6 +505,8 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t const char __user *p; ssize_t ret; + if (!(file->f_mode & FMODE_WRITE)) + return -EBADF; if (!(file->f_mode & FMODE_CAN_WRITE)) return -EINVAL;