From patchwork Mon Jun 15 12:12:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11604655 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 EBD2E92A for ; Mon, 15 Jun 2020 12:13:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3FEC206D7 for ; Mon, 15 Jun 2020 12:13:22 +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="KL4PXATW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729855AbgFOMNS (ORCPT ); Mon, 15 Jun 2020 08:13:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729854AbgFOMNR (ORCPT ); Mon, 15 Jun 2020 08:13:17 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F0BFC061A0E; Mon, 15 Jun 2020 05:13:17 -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=2BlRuJ2pmNZR4h52dmedFXwTdTgWfjbTqLeho/km0oQ=; b=KL4PXATW5bzWQa6KgiIiBdB2Fz X4SbmtBexwGNoK+sfLzMEe07mtCa6yoATAtxW3bgtPrIBNGYmVsC3pqNMFzCnfDXEqZ8EwsSauN68 ihvICY3c3i5Afl6bBW9x8KxperepdeS/Y76TywQnXn67ybv5tvxh3hmoDxkcgQNwuRivuM2L3Zj6G 6WP3n5j1aSVHmDWB2hwxEHkfmq+o0/WahF6XJt0V4CPdQW0WoNC0srSoEsJ4nvcRpX+F6NFtBVP4t Yfu/TiZhQ7u/rvUElGAuaWtvzyPT+OCxDhl30nUETjbiKzqZjoWNF2ElfBvb5JHrkoCYOZA9aTkfU VSyLjlYA==; Received: from 195-192-102-148.dyn.cablelink.at ([195.192.102.148] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jknzG-00070t-2U; Mon, 15 Jun 2020 12:13:14 +0000 From: Christoph Hellwig To: Al Viro Cc: Linus Torvalds , 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 05/13] fs: check FMODE_WRITE in __kernel_write Date: Mon, 15 Jun 2020 14:12:49 +0200 Message-Id: <20200615121257.798894-6-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200615121257.798894-1-hch@lst.de> References: <20200615121257.798894-1-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 2c601d853ff3d8..76be155ad98242 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;