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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D42A3C2BAEE for ; Wed, 11 Mar 2020 18:49:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7241520737 for ; Wed, 11 Mar 2020 18:50:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="m+VDswWk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7241520737 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EFBA26B0005; Wed, 11 Mar 2020 14:49:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EABC86B0006; Wed, 11 Mar 2020 14:49:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D99A86B0007; Wed, 11 Mar 2020 14:49:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0202.hostedemail.com [216.40.44.202]) by kanga.kvack.org (Postfix) with ESMTP id C022E6B0005 for ; Wed, 11 Mar 2020 14:49:58 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 730218248047 for ; Wed, 11 Mar 2020 18:49:58 +0000 (UTC) X-FDA: 76583970876.29.pin02_57070285d721f X-HE-Tag: pin02_57070285d721f X-Filterd-Recvd-Size: 4886 Received: from mail-pl1-f195.google.com (mail-pl1-f195.google.com [209.85.214.195]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Wed, 11 Mar 2020 18:49:57 +0000 (UTC) Received: by mail-pl1-f195.google.com with SMTP id ay11so1516402plb.0 for ; Wed, 11 Mar 2020 11:49:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=1O5mNwRKS3WQZf3p7S3pD40Ezb3WQVwbR9o3MD95weI=; b=m+VDswWkn7oQWzwAESTvbUWn0hrwmnnEnt9dMsZtQKuIuHrc/4r8XX+lx3mOiCCcLf wm8Cz5DjMVhJvDP2VVG0zJ6SHpUILyY5dzan67JIz+4vG+F5i9SL1nVUXx4dramPRkPf S6tllCNLWc9gmhewcz7zNJik0de/BY4hu9fI8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=1O5mNwRKS3WQZf3p7S3pD40Ezb3WQVwbR9o3MD95weI=; b=ARTfjM4QicNrF8KPkX6gyK9fa28ndQOkgVDzznwExjNCeDdnZkf8kK3l3U45ReZhjb E0WilPCXkJfmSGyJrgvalnCjACT6AKXouLatZiuzRBYL31m/Dzuns6c6YnAnGSETZwtL 4AOYLRz8IsWWjJDA3ryaMCNjD7IK9k23eeYnSIeRcS2LaOkxr3EhzGbRwwyTAUCmOfuE vLSqcyxUeXFwsVf11AJPhn1oYjNncOuHOQ2Fr4Rh2SURs/CgNKWCJZ1w9LBsdzjx3OmD eNh4sDPMWufuJiwg15HbvNWfq2EH93/2q6yfr3ifJiaLPSmMrSoeZ8KL/LQ+wAlm+D7+ V69A== X-Gm-Message-State: ANhLgQ2BSIDccTytejsrExQTi5nd2aVsbysG9/QSq/khrPuP5k/ytokX uCI8uZDE7aG2edoVCvoUhDNLAg== X-Google-Smtp-Source: ADFU+vuib6jYbHkTB4keLnEAQw9IkBZ0gBuO2NqH2stMX84aRVJNXeHWoxrV2IDBqjWVCcvlTbvu+Q== X-Received: by 2002:a17:90a:d80b:: with SMTP id a11mr131940pjv.21.1583952596740; Wed, 11 Mar 2020 11:49:56 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id 13sm49989285pgo.13.2020.03.11.11.49.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2020 11:49:55 -0700 (PDT) Date: Wed, 11 Mar 2020 11:49:54 -0700 From: Kees Cook To: "Eric W. Biederman" Cc: Jann Horn , Christian Brauner , Bernd Edlinger , Jonathan Corbet , Alexander Viro , Andrew Morton , Alexey Dobriyan , Thomas Gleixner , Oleg Nesterov , Frederic Weisbecker , Andrei Vagin , Ingo Molnar , "Peter Zijlstra (Intel)" , Yuyang Du , David Hildenbrand , Sebastian Andrzej Siewior , Anshuman Khandual , David Howells , James Morris , Greg Kroah-Hartman , Shakeel Butt , Jason Gunthorpe , Christian Kellner , Andrea Arcangeli , Aleksa Sarai , "Dmitry V. Levin" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "stable@vger.kernel.org" , "linux-api@vger.kernel.org" , Arnd Bergmann , Sargun Dhillon Subject: Re: [PATCH] pidfd: Stop taking cred_guard_mutex Message-ID: <202003111148.19578AA@keescook> References: <877dztz415.fsf@x220.int.ebiederm.org> <20200309201729.yk5sd26v4bz4gtou@wittgenstein> <87k13txnig.fsf@x220.int.ebiederm.org> <20200310085540.pztaty2mj62xt2nm@wittgenstein> <87wo7svy96.fsf_-_@x220.int.ebiederm.org> <87k13sui1p.fsf@x220.int.ebiederm.org> <87lfo8rkqo.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87lfo8rkqo.fsf@x220.int.ebiederm.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 10, 2020 at 03:57:35PM -0500, Eric W. Biederman wrote: > So ptrace_attach and seccomp use the cred_guard_mutex to guarantee > a deadlock. Well, that's the result, but seccomp uses it because it wants to be certain that credentials and no_new_privs are changed together "atomically". -- Kees Cook