From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 236CCC65BAE for ; Thu, 13 Dec 2018 12:16:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF0EA2087F for ; Thu, 13 Dec 2018 12:16:50 +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="U0v7yaA5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DF0EA2087F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-security-module-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728910AbeLMMQu (ORCPT ); Thu, 13 Dec 2018 07:16:50 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:47792 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728806AbeLMMQu (ORCPT ); Thu, 13 Dec 2018 07:16:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=4ZXtW55JAa/vg3hQkSbYV2kNZlrL5oduqPKvGV7TOe0=; b=U0v7yaA5V9wVYtvPRItgV/9ZUY US6ZjDY/ysvQOu15Y3/azoIN4C0QCObr9ZWszHqkM1ZcF0aOW7+FA/q2SjXv4Khz3tmknei2qrrSH tAltIO3mgfQeLH5UD+52ZXFMHgTQNVz24x90l7Nb+WLyjkuO+4ZY5VArrMOtvpSR2ZnPkv+Bw3Q2M 5cOyOg3CvX3E1Gn12ctQm63+qeCJ9jPQOSGIMpGMdUlXm/SPfBYaJUXmWOOixVN1o6eg0AZ5KUtf2 IbL4KjwryqD9vigGzf8sRYhwVqNtJdoN3oGcizaG76TwznbWNSyenbBGXowAUSJkX4FKXXTuO6qqt PeYnujiw==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gXPv4-0002z1-75; Thu, 13 Dec 2018 12:16:46 +0000 Date: Thu, 13 Dec 2018 04:16:46 -0800 From: Matthew Wilcox To: Mimi Zohar Cc: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= , linux-kernel@vger.kernel.org, Al Viro , James Morris , Jonathan Corbet , Kees Cook , Matthew Garrett , Michael Kerrisk , =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= , Philippe =?iso-8859-1?Q?Tr=E9buchet?= , Shuah Khan , Thibaut Sautereau , Vincent Strubel , Yves-Alexis Perez , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH v1 0/5] Add support for O_MAYEXEC Message-ID: <20181213121645.GN6830@bombadil.infradead.org> References: <20181212081712.32347-1-mic@digikod.net> <20181213030228.GM6830@bombadil.infradead.org> <1544699060.6703.11.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1544699060.6703.11.camel@linux.ibm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Thu, Dec 13, 2018 at 06:04:20AM -0500, Mimi Zohar wrote: > > I don't have a problem with the concept, but we're running low on O_ bits. > > Does this have to be done before the process gets a file descriptor, > > or could we have a new syscall? Since we're going to be changing the > > interpreters anyway, it doesn't seem like too much of an imposition to > > ask them to use: > > > > int verify_for_exec(int fd) > > > > instead of adding an O_MAYEXEC. > > The indication needs to be set during file open, before the open > returns to the caller.  This is the point where ima_file_check() > verifies the file's signature.  On failure, access to the file is > denied. I understand that's what happens today, but do we need to do it that way? There's no harm in the interpreter having an fd to a file if it knows not to execute it. This is different from a program opening a file and having the LSM deny access to it because it violates the security model.