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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 4C153C17447 for ; Mon, 11 Nov 2019 20:25:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 231F4206A3 for ; Mon, 11 Nov 2019 20:25:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="dWfGQJGb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727734AbfKKUZB (ORCPT ); Mon, 11 Nov 2019 15:25:01 -0500 Received: from mail-oi1-f193.google.com ([209.85.167.193]:40995 "EHLO mail-oi1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727392AbfKKUZB (ORCPT ); Mon, 11 Nov 2019 15:25:01 -0500 Received: by mail-oi1-f193.google.com with SMTP id e9so12668564oif.8 for ; Mon, 11 Nov 2019 12:25:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=vOfyNjirhZJpCYD/14r+NEmeylR+17cr7FHoRrl56Eg=; b=dWfGQJGbeWaicejJBkwOAjX8oYfy6+0uZOeGW/ISyKeITlGByBW9LZD0ef0cBcubzE 5VowYn+IFL3EjC5xJN98eoBJ9cxZurvUFXmKGHv1gMlwUAt2IJQhnG3HCcFE4yDs3pWb XLdbPgHB58v6MJSb7XzlKSm8nHqKiutilSbBjh40Ow8IDfWkiK9Zc47coLaMutfIxTpv xiOAoKCAR3q6SIm1Xx6H30p83uuVTAoIrXdrC6aCa9jLbptNxGMx/X6uQA01wED4UyBo ad+zy/cCPRnzazbtYB2TFdfXk0pT7JRbUbwCY3lgBPQdFIOMfyQqU8r4WxBMICIuDJ57 wbYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vOfyNjirhZJpCYD/14r+NEmeylR+17cr7FHoRrl56Eg=; b=k4kWANlLHv9T3C8PkS6cbcbxCWzVTAN7nyAa2ngK3HU4GVXj5d/JeYzzUwvk6k0VM0 qaZlw8NqU3Pm+UAjI9ZKGetGw13HDp3dUrFVwWUqDD99e/TkvFOEj+kb9cGu/K8SU9g6 ArbXWQpF6njj9+SWmBFaWgD0Nq4Ce9glhNSEt4RYR4Ugh1RJLCGuKNUXlIgg48d59XAO jFehJqFxUp6RoYhJCgcKHow1vZLFtvRd7H267MHTnd9YQGb8Aryt3JGQLHK9+TsyDtZn srJcJ0NF12r2RgJsD0tR3nDvx2RhUG5rNCfxHqstxmQintSd5zvzuwuk9YYgcaAdN4NZ K/tg== X-Gm-Message-State: APjAAAVk7hqYQ4DNpEzv13sZxPGaulGzV3S1bWAjI4mcrHiE/i7yMQAa Jjv9WUhD4aowpWiEyVLYESW+7CDkNl8zTVaiDJ81qw== X-Google-Smtp-Source: APXvYqy1VzfjRJuVb1MDElB7+dHlzd2kffgrpg+vPM+DJzWy3J/vzxZA0hSOvGwfYP2VYVG9yRo/VcuFRjBJ95zHNq8= X-Received: by 2002:a05:6808:9a1:: with SMTP id e1mr689381oig.175.1573503899982; Mon, 11 Nov 2019 12:24:59 -0800 (PST) MIME-Version: 1.0 References: <20191107151941.dw4gtul5lrtax4se@wittgenstein> <2eb2ab4c-b177-29aa-cdc4-420b24cfd7b3@gmail.com> <20191111165800.GD7017@mit.edu> In-Reply-To: <20191111165800.GD7017@mit.edu> From: Jann Horn Date: Mon, 11 Nov 2019 21:24:33 +0100 Message-ID: Subject: Re: For review: documentation of clone3() system call To: "Theodore Y. Ts'o" Cc: "Michael Kerrisk (man-pages)" , Christian Brauner , Florian Weimer , Christian Brauner , lkml , linux-man , Kees Cook , Oleg Nesterov , Arnd Bergmann , David Howells , Pavel Emelyanov , Andrew Morton , Adrian Reber , Andrei Vagin , Linux API , Ingo Molnar Content-Type: text/plain; charset="UTF-8" Sender: linux-man-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org On Mon, Nov 11, 2019 at 5:58 PM Theodore Y. Ts'o wrote: > On Mon, Nov 11, 2019 at 03:55:35PM +0100, Jann Horn wrote: > > Not on Linux, but on OpenBSD, they do use MAP_STACK now AFAIK; this > > was announced here: > > . > > Basically they periodically check whether the userspace stack pointer > > points into a MAP_STACK region, and if not, they kill the process. So > > even if it's a no-op on Linux... > > Hmm, is that something we should do in Linux? Even if we only check > on syscall entry, which should be pretty inexpensive, it seems like it > would be very effective in protecting various ROP techniques. I'm not a big fan, especially if that would only happen on syscall entry; at the point where you have enough control to perform syscalls, it probably isn't too difficult to move your ROP stack over to a legitimate stack.