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=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 35680C282DA for ; Wed, 17 Apr 2019 14:11:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0180B206BA for ; Wed, 17 Apr 2019 14:11:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brauner.io header.i=@brauner.io header.b="MqHiVmP0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732433AbfDQOLt (ORCPT ); Wed, 17 Apr 2019 10:11:49 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:40063 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732306AbfDQOLs (ORCPT ); Wed, 17 Apr 2019 10:11:48 -0400 Received: by mail-wr1-f67.google.com with SMTP id h4so32174740wre.7 for ; Wed, 17 Apr 2019 07:11:47 -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=GULFxHwqyAV9kpsq187lwfIVbAtO+Q4/JzWiX8uyBFA=; b=MqHiVmP0Xcdy6SmGvEIWqmMLIbI2mPGlzxNmEv/4PZKWO6cIqSi+bLeFBX+YiFnwM9 4vmtLmYN4D7SwS9+2B+RNzuEX/8MwtwUZ0dqTBiCtoTAClKvK8EWhgVIjYfGgKWZPDeZ hd1h+tgsArsnZnG7aNgAmSx41tsKdTgZXRqsU46JPIWbyt+LAHqSoystYtiZGQC085fR eogd4/WrSk5mbTAyqteaPXrKWEfYyqdOF3ntMNXR5wxtC3mdes0XsWJAgAB7ZpiXBZNT Uq16Jxhuqvl/uNy8jXYPpcHEqI1nwpWNUv0sOthaufw49U3eCqvWjWdEdbDV1bOoGfAU VKdQ== 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=GULFxHwqyAV9kpsq187lwfIVbAtO+Q4/JzWiX8uyBFA=; b=PiJNWXZ6qrmaNULfMRKwZMThmyvW9GcIxbyu9zTbpkN45/zc/54+LmdKGhHF9f8s61 q6NC7UFmDWX5CsyWlDAXhr22/S4ZqewUVjdYxgOszVchi3JC/TcyWhSVdiKLXyD3gI87 7mqQ+YYpR2A3X/XoPV5P+nwLDt2Cmnq0jpuKK6TBhYEDoGQ+JfEmLsBFKPkmB5x9ogaA mSraSHQhjTFewH97tY3U+74IVhqDzSe7ING5QclXcJ+oPeLG498NsUFy9N2056g5Fw80 IB6aicFQ3/CixmqwQcNK8Dea71TR1BlxrvPs+eCiIio6/rV41J7PhIGXwRwUzwSU6dJU rijA== X-Gm-Message-State: APjAAAWeSMdvRfwqTSX2V80JSowDiGmD7U9BfJTy14ox9QDrCqLaEw0K T/Kyu25k5itdqDkVSTE7iLhO4g== X-Google-Smtp-Source: APXvYqx1EM0JXdxGvua/SCzYuSOMqSNPyzF32CWCAvCE+49wfkROUuMItsKXz7quAHMx3wAwrd16Ww== X-Received: by 2002:a5d:538d:: with SMTP id d13mr58665857wrv.45.1555510306847; Wed, 17 Apr 2019 07:11:46 -0700 (PDT) Received: from brauner.io ([185.197.132.10]) by smtp.gmail.com with ESMTPSA id y127sm3345752wmg.29.2019.04.17.07.11.45 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 17 Apr 2019 07:11:46 -0700 (PDT) Date: Wed, 17 Apr 2019 16:11:44 +0200 From: Christian Brauner To: Oleg Nesterov Cc: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, jannh@google.com, dhowells@redhat.com, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, serge@hallyn.com, luto@kernel.org, arnd@arndb.de, ebiederm@xmission.com, keescook@chromium.org, tglx@linutronix.de, mtk.manpages@gmail.com, akpm@linux-foundation.org, cyphar@cyphar.com, joel@joelfernandes.org, dancol@google.com Subject: Re: [PATCH v1 3/4] signal: support CLONE_PIDFD with pidfd_send_signal Message-ID: <20190417141144.k2kmg7hd7pdpywyw@brauner.io> References: <20190416170233.10208-1-christian@brauner.io> <20190416170233.10208-4-christian@brauner.io> <20190417140106.GG32622@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190417140106.GG32622@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 Wed, Apr 17, 2019 at 04:01:06PM +0200, Oleg Nesterov wrote: > On 04/16, Christian Brauner wrote: > > > > @@ -3581,12 +3588,12 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, > > if (flags) > > return -EINVAL; > > > > - f = fdget_raw(pidfd); > > + f = fdget(pidfd); > > could you explain this change? > > I am just curious, I don't understand why should we disallow O_PATH and how > this connects to this patch. Sending a signal through a pidfd is considered to be on a par with a "write" to that pidfd. Additionally, we use the fops associated with the fd to detect whether it is actually a pidfd or not. This is not possible with O_PATH since f_ops will be set to dummy fops. So we already correctly error out since we detect that it is an O_PATH before fdget_raw(). This just takes the opportunity to fix it. Christian