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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 3465EC43603 for ; Fri, 20 Dec 2019 01:43:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBFDB24684 for ; Fri, 20 Dec 2019 01:43:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576806212; bh=9ejuSSpwcIgoC1vtIrf1QW8XeawMCi6i1EBo5T44lto=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=Mz7VPStHp7BI7SZY38Bu6ryyqCBr+jpLznx/FruN69HNAYBMJggA5meSAwUWzhV/N sjoEKE00YxYB8eJ52MHn0lkk4ebHUfqfKyECdWPME7cDt4dVHl73HZ264l0OcaRsRQ Fzb8c7/VWvw5FHZ9GojK4jeaRGLSNjHfR3RUItfw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727269AbfLTBnb (ORCPT ); Thu, 19 Dec 2019 20:43:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:48316 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727020AbfLTBna (ORCPT ); Thu, 19 Dec 2019 20:43:30 -0500 Received: from mail-wr1-f49.google.com (mail-wr1-f49.google.com [209.85.221.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 46B5624687 for ; Fri, 20 Dec 2019 01:43:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576806210; bh=9ejuSSpwcIgoC1vtIrf1QW8XeawMCi6i1EBo5T44lto=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=JfMhr7V0wOAkVFs2SKNvA7dd8/uf8OvCUvrPu/E+fvrZWV1YEq9FzyAehZ+V7GmVI UlDMYIVSnn+r6U8JIGwm7D889lEyw6cFQYiyhDwj9OfXz1LegMVJfzUMzMjhhP/AVL ASF5a8ihUb8caQAHihcy7CgZW+qF+n8kOPLeWFds= Received: by mail-wr1-f49.google.com with SMTP id z3so7874944wru.3 for ; Thu, 19 Dec 2019 17:43:30 -0800 (PST) X-Gm-Message-State: APjAAAVR3Z58FZbrHjTVvqOCbJsH62XSEfLoFg64NWHJYi5iNYAM8bKt CRMSAgoq1c8ZSv/4ZPls0aj8XKdiOv4m2cD+CKFCuQ== X-Google-Smtp-Source: APXvYqw3HP/VhP6dKqWKDMvRB9Y+Ln/rjo5DtmsDHh8oLRC1zCVOr/TQ6d9paG0FxgM7qE2ND0+e7f4/JMUkGjTDBL4= X-Received: by 2002:adf:eb09:: with SMTP id s9mr12892287wrn.61.1576806208779; Thu, 19 Dec 2019 17:43:28 -0800 (PST) MIME-Version: 1.0 References: <20191218235459.GA17271@ircssh-2.c.rugged-nimbus-611.internal> In-Reply-To: <20191218235459.GA17271@ircssh-2.c.rugged-nimbus-611.internal> From: Andy Lutomirski Date: Thu, 19 Dec 2019 17:43:17 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4 2/5] pid: Add PIDFD_IOCTL_GETFD to fetch file descriptors from processes To: Sargun Dhillon Cc: LKML , Linux Containers , Linux API , Linux FS Devel , Tycho Andersen , Jann Horn , Aleksa Sarai , Christian Brauner , Oleg Nesterov , Al Viro , gpascutto@mozilla.com, ealvarez@mozilla.com, Florian Weimer , jld@mozilla.com, Arnd Bergmann Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 18, 2019 at 3:55 PM Sargun Dhillon wrote: > > + > + if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { > + file = ERR_PTR(-EPERM); > + goto out; > + } I don't think this is MODE_READ. By copying an fd from the task, you can easily change its state. IMO it would be really nice if pidfd could act more like a capability here and carry a ptrace mode, for example. But I guess it doesn't right now. --Andy