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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_PASS,USER_AGENT_NEOMUTT 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 A653EC282DA for ; Wed, 17 Apr 2019 13:03:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C0C42173C for ; Wed, 17 Apr 2019 13:03:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brauner.io header.i=@brauner.io header.b="WRQzIrUY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732154AbfDQNDl (ORCPT ); Wed, 17 Apr 2019 09:03:41 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:35794 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729940AbfDQNDk (ORCPT ); Wed, 17 Apr 2019 09:03:40 -0400 Received: by mail-wm1-f65.google.com with SMTP id y197so3548491wmd.0 for ; Wed, 17 Apr 2019 06:03:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brauner.io; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=cejhRTfWhhlFH6fanfQsVN7dbGnTDgRUCk8MGU3ZSYo=; b=WRQzIrUYwNw1/iNH34bfBmOBn+jf/W9if2TBGaCc7qQSnyomzEajvUd/pVjJe4ARJk sGKdwRKkSyayNANAxn30nQ1nh5+8ZR3VF6gvFgE9PfMFyiH48DE8RI8DRimXnG7RWy1J 31e9o//JhD+/nr719dX13Ybu3Od0QmVj0CoK6SMHuD3dHr0Q4dzoQL63fKvcirXGINcO fq+MOXI/E8b7fZNP/tVuUwV8DdAhGWSZoLuzKu1LHu5v4gTh1Fx8lUXh2Ub/m16DlL7d zN1u7ALNgP2REw8oXu29iDeTVJFGHQlvBTHkfDKGMJ123KIECVNuRRQ5H8fUwFyqZxH6 RoFQ== 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:user-agent; bh=cejhRTfWhhlFH6fanfQsVN7dbGnTDgRUCk8MGU3ZSYo=; b=EkFEKhkl/Q5WqsLKVWzdiF72Vetff4ZYxt+Di9PyKBDNqFMYe0C/2wmjurBaSy7OY7 kxI2uGWWnEDtpbkxw9i5ltr2raftx5BFogotKVmLKSBmC25cCFRExqWdAoR4w0GE9cPF mftzGjF3nXWTDzHMVESSWULzt5MQejr4rvD/QosVJ5ux0K5N7DS+gC9SDL8Wce56M8fH 8p0x7v7TuGwk8T47cis586M7Ulw6+TtJpIwOBB9N5OqfGa15aHtywHbKMOPPuDR0RPTJ QQmm1yicimBnr750XYj7sPZBCQ2YS2T0mupt6rAj8j7m6E4zdQ+dfALpZFQpaQG4mgzU W6oA== X-Gm-Message-State: APjAAAVqrCRC38enFGQ8dH0YgC4zKNEx4C1fXbHMMpswZY8n77cWK2N4 eUP+fFbqbMpGdTP0OjO7zInUnw== X-Google-Smtp-Source: APXvYqzupwLA/R31cjqq1W3HOP0r1EP8Dbe6PetLMdsurtKWlEIEfUDQaIyq9nTqCXHKq6xhFWvaKg== X-Received: by 2002:a1c:9991:: with SMTP id b139mr29680031wme.53.1555506219137; Wed, 17 Apr 2019 06:03:39 -0700 (PDT) Received: from brauner.io ([185.197.132.10]) by smtp.gmail.com with ESMTPSA id w16sm79760431wrt.84.2019.04.17.06.03.37 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 17 Apr 2019 06:03:38 -0700 (PDT) Date: Wed, 17 Apr 2019 15:03:37 +0200 From: Christian Brauner To: Oleg Nesterov Cc: Jann Horn , "Eric W. Biederman" , Arnd Bergmann , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH] signal: don't silently convert SI_USER signals to non-current pidfd Message-ID: <20190417130336.i55vmf3x6cby2mvi@brauner.io> References: <20190330021232.191205-1-jannh@google.com> <20190408131315.GA24111@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190408131315.GA24111@redhat.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 08, 2019 at 03:13:16PM +0200, Oleg Nesterov wrote: > On 03/30, Jann Horn wrote: > > > > --- a/kernel/signal.c > > +++ b/kernel/signal.c > > @@ -3605,16 +3605,11 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, > > if (unlikely(sig != kinfo.si_signo)) > > goto err; > > > > + /* Only allow sending arbitrary signals to yourself. */ > > + ret = -EPERM; > > if ((task_pid(current) != pid) && > > - (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) { > > - /* Only allow sending arbitrary signals to yourself. */ > > - ret = -EPERM; > > - if (kinfo.si_code != SI_USER) > > - goto err; > > - > > - /* Turn this into a regular kill signal. */ > > - prepare_kill_siginfo(sig, &kinfo); > > - } > > + (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) > > + goto err; > > ACK. > Sorry Oleg. I missed that message somehow. > > but perhaps it should always fail, even if task_pid(current) == pid. > > sys_rt_sigqueueinfo() allows to send any siginfo to yourself, but this is only needed > for checkpoint/restart. Yes, that's why this was added. I would leave it in exactly because of checkpoint/restart. I have sympathies for "this [...] project by various mad Russians" [1] and it doesn't really hurt us. :) [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=099469502f62fbe0d7e4f0b83a2f22538367f734 Christian