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 97F0AC04EB8 for ; Fri, 30 Nov 2018 11:29:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4229F206B7 for ; Fri, 30 Nov 2018 11:29:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4229F206B7 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 S1726648AbeK3WiZ (ORCPT ); Fri, 30 Nov 2018 17:38:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59828 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726459AbeK3WiZ (ORCPT ); Fri, 30 Nov 2018 17:38:25 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3FB683082141; Fri, 30 Nov 2018 11:29:27 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.12]) by smtp.corp.redhat.com (Postfix) with SMTP id 20E4F61081; Fri, 30 Nov 2018 11:29:21 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 30 Nov 2018 12:29:26 +0100 (CET) Date: Fri, 30 Nov 2018 12:29:21 +0100 From: Oleg Nesterov To: "Dmitry V. Levin" Cc: Kees Cook , Jann Horn , Michael Ellerman , Elvira Khabirova , Eugene Syromyatnikov , Steven Rostedt , linux-kernel@vger.kernel.org, Andy Lutomirski , linux-api@vger.kernel.org, Ingo Molnar , strace-devel@lists.strace.io Subject: Re: [PATCH v4 1/2] ptrace: save the type of syscall-stop in ptrace_message Message-ID: <20181130112920.GD23670@redhat.com> References: <20181128130439.GB28206@altlinux.org> <20181128130601.GC28206@altlinux.org> <20181128134913.GC30395@redhat.com> <20181128140533.GF28206@altlinux.org> <20181128142006.GE30395@redhat.com> <20181128152346.GG28206@altlinux.org> <20181128221125.GA2800@altlinux.org> <20181129144742.GB10645@redhat.com> <20181129211044.GA20529@altlinux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181129211044.GA20529@altlinux.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Fri, 30 Nov 2018 11:29:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/30, Dmitry V. Levin wrote: > > On Thu, Nov 29, 2018 at 03:47:43PM +0100, Oleg Nesterov wrote: > > > > so that PTRACE_GETEVENTMSG users can easily tell > > > whether this new semantics is supported by the kernel or not. > > > > Yes. And how much this can help? Again, an application can trivially detect > > if this feature implemented or not, and it should do this anyway if it wants > > to (try to) use PTRACE_EVENTMSG_SYSCALL_ENTRY/EXIT ? > > How an application can easily detect whether this feature is implemented? As I already said, it can just do ptrace(PTRACE_GET_SYSCALL_INFO, NULL) ? If it returns -EIO then this feature is not implemented. Any other error code (actually EINVAL or EFAULT) means it is implemented. Oleg.