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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 A2158C47082 for ; Tue, 8 Jun 2021 23:38:37 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id ECCFA61185 for ; Tue, 8 Jun 2021 23:38:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECCFA61185 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-21294-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 28236 invoked by uid 550); 8 Jun 2021 23:38:30 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 28216 invoked from network); 8 Jun 2021 23:38:29 -0000 IronPort-SDR: PlxwlQv+pS4LHxTc8XbaBUAlasHVc2qKrEQ+8Zqsxx/pjShEUDI2Ol+qicGjga2SwH8aY8fsGL jRbNiOV2Q6Bg== X-IronPort-AV: E=McAfee;i="6200,9189,10009"; a="290595554" X-IronPort-AV: E=Sophos;i="5.83,259,1616482800"; d="scan'208";a="290595554" IronPort-SDR: pE4bdvjF0J9Yr2v3Y5b0EYAhXyF61Gs96zOXtSka7ND8veuaNykb0Auifm2a4kdYM6xKQUkwk/ irwRg3JJ0msA== X-IronPort-AV: E=Sophos;i="5.83,259,1616482800"; d="scan'208";a="551784529" Subject: Re: [PATCH v8 0/8] Fork brute force attack mitigation To: Kees Cook , John Wood Cc: Jann Horn , Jonathan Corbet , James Morris , "Serge E. Hallyn" , Shuah Khan , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Arnd Bergmann , valdis.kletnieks@vt.edu, Greg Kroah-Hartman , Randy Dunlap , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arch@vger.kernel.org, linux-hardening@vger.kernel.org, kernel-hardening@lists.openwall.com References: <20210605150405.6936-1-john.wood@gmx.com> <202106081616.EC17DC1D0D@keescook> From: Andi Kleen Message-ID: Date: Tue, 8 Jun 2021 16:38:15 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <202106081616.EC17DC1D0D@keescook> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US On 6/8/2021 4:19 PM, Kees Cook wrote: > On Sat, Jun 05, 2021 at 05:03:57PM +0200, John Wood wrote: >> [...] >> the kselftest to avoid the detection ;) ). So, in this version, to track >> all the statistical data (info related with application crashes), the >> extended attributes feature for the executable files are used. The xattr is >> also used to mark the executables as "not allowed" when an attack is >> detected. Then, the execve system call rely on this flag to avoid following >> executions of this file. > I have some concerns about this being actually usable and not creating > DoS situations. For example, let's say an attacker had found a hard-to-hit > bug in "sudo", and starts brute forcing it. When the brute LSM notices, > it'll make "sudo" unusable for the entire system, yes? > > And a reboot won't fix it, either, IIUC. > The whole point of the mitigation is to trade potential attacks against DOS. If you're worried about DOS the whole thing is not for you. -Andi