From patchwork Wed May 13 06:56:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11545227 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 A08D814B4 for ; Wed, 13 May 2020 06:58:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 886412176D for ; Wed, 13 May 2020 06:58:07 +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="eWlybqD1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729931AbgEMG6G (ORCPT ); Wed, 13 May 2020 02:58:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730102AbgEMG5O (ORCPT ); Wed, 13 May 2020 02:57:14 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00F55C061A0C; Tue, 12 May 2020 23:57:14 -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=LiemweaQJNNyLn4dfMO7A8hjFLXFG2PuwhKLysUSths=; b=eWlybqD1KoTTOjAxPIZ2GmGWuc r0mVzo6v3VqIjQsb1BJnI2VjR76FE6lLwK8iPOkLkniP/nfrJ0HvsMbGVVwb9dxmOFJqw4rLzstig /AOO6BOIDBHii8SHUYx5IOVsShPqYwPBXLqTKTKBhFWohbuk1wq8vGYbjFt1N57z/Qy2lB5KQhtZo EBr/cuX/UaWaQgc1OmWk0ayffxDDRoMTObYde4/cIkEUoDzQO6pkUpiUZJvIJ7/G2keHRveErX+22 eHW8Spdj0zreRaHWSiScS5jdBaDJFGXKD6kB8Lbt08MtLXYAF/FdfIsVQqY80hDNZp/eNDpiNTtAs zXXZfWsg==; Received: from [2001:4bb8:180:9d3f:c70:4a89:bc61:2] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYlKJ-0003WJ-K9; Wed, 13 May 2020 06:57:12 +0000 From: Christoph Hellwig To: Al Viro Cc: Ian Kent , David Howells , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, netfilter-devel@vger.kernel.org Subject: [PATCH 05/14] fs: check FMODE_WRITE in __kernel_write Date: Wed, 13 May 2020 08:56:47 +0200 Message-Id: <20200513065656.2110441-6-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200513065656.2110441-1-hch@lst.de> References: <20200513065656.2110441-1-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 2c601d853ff3d..76be155ad9824 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;