From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by sourceware.org (Postfix) with ESMTP id 85B943858D37 for ; Tue, 25 Aug 2020 12:16:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 85B943858D37 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-409-W6EoHqjMNsWp7nMPwTSh6w-1; Tue, 25 Aug 2020 08:16:43 -0400 X-MC-Unique: W6EoHqjMNsWp7nMPwTSh6w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3C484189610F; Tue, 25 Aug 2020 12:16:42 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-37.ams2.redhat.com [10.36.112.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8B478709C4; Tue, 25 Aug 2020 12:16:41 +0000 (UTC) From: Florian Weimer To: Andreas Schwab Cc: libc-alpha@sourceware.org Subject: Re: [PATCH 0/5] Linux: lchmod and AT_SYMLINK_NOFOLLOW support for fchmodat References: <877dux5hf6.fsf@igel.home> <87blk9ry5d.fsf@oldenburg2.str.redhat.com> <875z97xbya.fsf@igel.home> <87y2m381lw.fsf@oldenburg2.str.redhat.com> <87wo1nvvxu.fsf@igel.home> <87imd77zqv.fsf@oldenburg2.str.redhat.com> <87sgcbvv8s.fsf@igel.home> <87eenv7zj2.fsf@oldenburg2.str.redhat.com> <87o8mzvuwj.fsf@igel.home> <877dtn7z6q.fsf@oldenburg2.str.redhat.com> <87k0xnvujz.fsf@igel.home> <87364b7yno.fsf@oldenburg2.str.redhat.com> <87ft8ax6rx.fsf@igel.home> Date: Tue, 25 Aug 2020 14:16:40 +0200 In-Reply-To: <87ft8ax6rx.fsf@igel.home> (Andreas Schwab's message of "Tue, 25 Aug 2020 14:13:38 +0200") Message-ID: <87tuwq7wev.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-7.3 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Aug 2020 12:16:47 -0000 * Andreas Schwab: > On Aug 25 2020, Florian Weimer wrote: > >> The point is to avoid a race condition where a symbolic link is >> introduced after the pathname has been created. > > But it causes regressions when /proc is not mounted. It does. But what we can we do? We should not implement lchmod or fchmodat with this race condition. We need kernel support for this. Palmer Dabbelt wrote a patch, but it hasn't been merged, and I don't know if he's still interested in it. Thanks, Florian