From owner-freebsd-current Thu Sep 3 03:01:55 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id DAA21496 for freebsd-current-outgoing; Thu, 3 Sep 1998 03:01:55 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from ns1.yes.no (ns1.yes.no [195.119.24.10]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id DAA21491 for ; Thu, 3 Sep 1998 03:01:53 -0700 (PDT) (envelope-from eivind@bitbox.follo.net) Received: from bitbox.follo.net (bitbox.follo.net [195.204.143.218]) by ns1.yes.no (8.9.1a/8.9.1) with ESMTP id MAA00362; Thu, 3 Sep 1998 12:00:39 +0200 (CEST) Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id MAA04811; Thu, 3 Sep 1998 12:00:32 +0200 (MET DST) Message-ID: <19980903120032.23400@follo.net> Date: Thu, 3 Sep 1998 12:00:32 +0200 From: Eivind Eklund To: Terry Lambert Cc: bde@zeta.org.au, current@FreeBSD.ORG Subject: Re: ELF binaries size References: <19980902145445.24306@follo.net> <199809030130.SAA03730@usr07.primenet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.89.1i In-Reply-To: <199809030130.SAA03730@usr07.primenet.com>; from Terry Lambert on Thu, Sep 03, 1998 at 01:30:56AM +0000 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, Sep 03, 1998 at 01:30:56AM +0000, Terry Lambert wrote: > Bruce answered the other; I'll answer this one: > > > Or am I missing something that should be obvious here? > > For a system to be secure, you must not permit code to be > written to by the process, only data. > > The only way you can do this is to map the page "read-only". > > If the code and the data do not butt up to each other on an > even page boundary, using the same physical page would be > wrong. This is because data needs the page to be mapped > "copy-on-write". > > You can't have both in the same page because the hardware only > enforces protections on full pages. But can you have it in the same _memory_? I don't care that much if ELF wastes a page mapping entry as it it wastes the memory an entire page use... Eivind. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message