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=-2.5 required=3.0 tests=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 EEFE4C04EB8 for ; Fri, 30 Nov 2018 10:17:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B763920863 for ; Fri, 30 Nov 2018 10:17:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B763920863 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726600AbeK3V0n (ORCPT ); Fri, 30 Nov 2018 16:26:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56612 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726469AbeK3V0n (ORCPT ); Fri, 30 Nov 2018 16:26:43 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1F330307D845; Fri, 30 Nov 2018 10:17:55 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.12]) by smtp.corp.redhat.com (Postfix) with SMTP id 7C23326194; Fri, 30 Nov 2018 10:17:52 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 30 Nov 2018 11:17:54 +0100 (CET) Date: Fri, 30 Nov 2018 11:17:51 +0100 From: Oleg Nesterov To: Tycho Andersen Cc: Kees Cook , Andy Lutomirski , "Eric W . Biederman" , "Serge E . Hallyn" , Christian Brauner , Tyler Hicks , Akihiro Suda , Aleksa Sarai , linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, linux-api@vger.kernel.org Subject: Re: [PATCH v8 1/2] seccomp: add a return code to trap to userspace Message-ID: <20181130101751.GA23670@redhat.com> References: <20181029224031.29809-1-tycho@tycho.ws> <20181029224031.29809-2-tycho@tycho.ws> <20181129230826.GB4676@cisco> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181129230826.GB4676@cisco> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Fri, 30 Nov 2018 10:17:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/29, Tycho Andersen wrote: > > /* > * These should never be seen by user programs. To return one of ERESTART* > * codes, signal_pending() MUST be set. Note that ptrace can observe these > * at syscall exit tracing, but they will never be left for the debugged user > * process to see. > */ > #define ERESTARTSYS 512 > > So basically, if you respond with -ERESTARTSYS with no signal pending, you'll > leak it to userspace. Yes, > It turns out this is already possible with > SECCOMP_RET_TRAP (and probably ptrace alone, Yes, > The question is: do we care? I think we do not care, debugger can do anything with the tracee. Oleg.