From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 11 Jan 2001 11:54:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 11 Jan 2001 11:54:46 -0500 Received: from saturn.cs.uml.edu ([129.63.8.2]:9226 "EHLO saturn.cs.uml.edu") by vger.kernel.org with ESMTP id ; Thu, 11 Jan 2001 11:54:36 -0500 From: "Albert D. Cahalan" Message-Id: <200101111650.f0BGoLG473101@saturn.cs.uml.edu> Subject: Re: Subtle MM bug To: sct@redhat.com (Stephen C. Tweedie) Date: Thu, 11 Jan 2001 11:50:21 -0500 (EST) Cc: torvalds@transmeta.com (Linus Torvalds), alan@lxorguk.ukuu.org.uk (Alan Cox), ak@suse.de (Andi Kleen), trond.myklebust@fys.uio.no (Trond Myklebust), phillips@innominate.de (Daniel Phillips), linux-kernel@vger.kernel.org, sct@redhat.com (Stephen Tweedie) In-Reply-To: <20010111125604.A17177@redhat.com> from "Stephen C. Tweedie" at Jan 11, 2001 12:56:04 PM X-Mailer: ELM [version 2.5 PL2] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Stephen C. Tweedie writes: > On Wed, Jan 10, 2001 at 12:11:16PM -0800, Linus Torvalds wrote: >> That said, we can easily support the notion of CLONE_CRED if >> we absolutely have to (and sane people just shouldn't use it), >> so if somebody wants to work on this for 2.5.x... > > But is it really worth the pain? I'd hate to have to audit the > entire VFS to make sure that it works if another thread changes our > credentials in the middle of a syscall, so we either end up having to > lock the credentials over every VFS syscall, or take a copy of the > credentials and pass it through every VFS internal call that we make. 1. each thread has a copy, and doesn't need to lock it 2. threads are commanded to change their own copy Credentials could be changed on syscall exit. It is a bit like doing signals I think, with less overhead than making userspace muck around with signal handlers and synchronization crud. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/