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=-0.8 required=3.0 tests=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 52B2BC2D0DC for ; Thu, 2 Jan 2020 08:58:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 212DD215A4 for ; Thu, 2 Jan 2020 08:58:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727817AbgABI6O convert rfc822-to-8bit (ORCPT ); Thu, 2 Jan 2020 03:58:14 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:39954 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727835AbgABI6O (ORCPT ); Thu, 2 Jan 2020 03:58:14 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-62-0-8UGkBPNxus61PG9BdnHA-1; Thu, 02 Jan 2020 08:58:10 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Thu, 2 Jan 2020 08:58:09 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Thu, 2 Jan 2020 08:58:09 +0000 From: David Laight To: 'Aleksa Sarai' , Linus Torvalds CC: Al Viro , David Howells , Eric Biederman , stable , Christian Brauner , Serge Hallyn , "dev@opencontainers.org" , "Linux Containers" , Linux API , linux-fsdevel , Linux Kernel Mailing List Subject: RE: [PATCH RFC 0/1] mount: universally disallow mounting over symlinks Thread-Topic: [PATCH RFC 0/1] mount: universally disallow mounting over symlinks Thread-Index: AQHVvuu3ha8TNgK7w0ufQ/mBgQviWKfXFrEg Date: Thu, 2 Jan 2020 08:58:09 +0000 Message-ID: References: <20191230052036.8765-1-cyphar@cyphar.com> <20191230054413.GX4203@ZenIV.linux.org.uk> <20191230054913.c5avdjqbygtur2l7@yavin.dot.cyphar.com> <20191230072959.62kcojxpthhdwmfa@yavin.dot.cyphar.com> <20191230083224.sbk2jspqmup43obs@yavin.dot.cyphar.com> In-Reply-To: <20191230083224.sbk2jspqmup43obs@yavin.dot.cyphar.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: 0-8UGkBPNxus61PG9BdnHA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Aleksa Sarai > Sent: 30 December 2019 08:32 ... > I'm not sure I agree -- as I mentioned in my other mail, re-opening > through /proc/self/fd/$n works *very* well and has for a long time (in > fact, both LXC and runc depend on this working). I thought it was marginally broken because it is followed as a symlink? On, for example, NetBSD /proc//fd/ is a real reference to the filesystem inode and can be used to link the file back into the filesystem if all the directory entries have been removed. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)