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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A8EDBC48BC2 for ; Wed, 23 Jun 2021 14:34:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9252F60FEB for ; Wed, 23 Jun 2021 14:34:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231326AbhFWOhN (ORCPT ); Wed, 23 Jun 2021 10:37:13 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:50778 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229523AbhFWOhK (ORCPT ); Wed, 23 Jun 2021 10:37:10 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out02.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1lw3xr-00DZwe-3m; Wed, 23 Jun 2021 08:34:51 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=email.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1lw3xp-001cBY-Vq; Wed, 23 Jun 2021 08:34:50 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Linus Torvalds Cc: Al Viro , Michael Schmitz , linux-arch , Jens Axboe , Oleg Nesterov , Linux Kernel Mailing List , Richard Henderson , Ivan Kokshaysky , Matt Turner , alpha , Geert Uytterhoeven , linux-m68k , Arnd Bergmann , Ley Foon Tan , Tejun Heo , Kees Cook References: <87sg1lwhvm.fsf@disp2133> <6e47eff8-d0a4-8390-1222-e975bfbf3a65@gmail.com> <924ec53c-2fd9-2e1c-bbb1-3fda49809be4@gmail.com> <87eed4v2dc.fsf@disp2133> <5929e116-fa61-b211-342a-c706dcb834ca@gmail.com> <87fsxjorgs.fsf@disp2133> <87a6njf0ia.fsf@disp2133> <87tulpbp19.fsf@disp2133> Date: Wed, 23 Jun 2021 09:33:50 -0500 In-Reply-To: (Linus Torvalds's message of "Tue, 22 Jun 2021 17:41:51 -0700") Message-ID: <87zgvgabw1.fsf@disp2133> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1lw3xp-001cBY-Vq;;;mid=<87zgvgabw1.fsf@disp2133>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19bOZKovoM2dTCNa4FoP/ARdkEwpSg1W4M= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: Kernel stack read with PTRACE_EVENT_EXIT and io_uring threads X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds writes: > On Tue, Jun 22, 2021 at 1:53 PM Eric W. Biederman wrote: >> >> Playing with it some more I think I have everything working working >> except for PTRACE_EVENT_SECCOMP (which can stay ptrace_event) and >> group_exit(2). >> >> Basically in exit sending yourself a signal and then calling do_exit >> from the signal handler is not unreasonable, as exit is an ordinary >> system call. > > Ok, this is a bit odd, but I do like the concept of just making > ptrace_event just post a signal, and have all ptrace things always be > handled at signal time (or the special system call entry/exit, which > is fine too). > >> For purposes of discussion this is my current draft implementation. > > I didn't check what is so different about exit_group() that you left > that as an exercise for the reader, but if that ends up then removing > the whole "wait synchromously for ptrace" cases for good I don't > _hate_ this. It's a bit odd, but it would be really nice to limit > where ptrace picks up data. I am still figuring out exit_group. I am hoping for sometime today. My intuition tells me I can do it, and I have a sense of what threads I need to pull to get there. I just don't know what the code is going to look like yet. Basically solving exit_group means moving ptrace_event out of do_exit. > We do end up doing that stuff in "get_signal()", and that means that > we have the interaction with io_uring calling it directly, but it's at > least not a new thing. The ugliest bit is having to repeat the wait_for_vfork_done both in fork and in get_signal. Eric