From owner-p4-projects Thu Oct 24 12:44:27 2002 Delivered-To: p4-projects@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 32767) id 20E1737B406; Thu, 24 Oct 2002 12:44:26 -0700 (PDT) Delivered-To: perforce@freebsd.org Received: from green.bikeshed.org (freefall.freebsd.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id 7724737B401; Thu, 24 Oct 2002 12:44:24 -0700 (PDT) Received: from green.bikeshed.org (9pc9770ni7g3nsuo@green.bikeshed.org [10.0.0.1] (may be forged)) by green.bikeshed.org (8.12.6/8.12.6) with ESMTP id g9OJiOPw023927; Thu, 24 Oct 2002 15:44:24 -0400 (EDT) (envelope-from green@green.bikeshed.org) Received: from localhost (green@localhost) by green.bikeshed.org (8.12.6/8.12.6/Submit) with ESMTP id g9OJiOMU023924; Thu, 24 Oct 2002 15:44:24 -0400 (EDT) Message-Id: <200210241944.g9OJiOMU023924@green.bikeshed.org> X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Robert Watson Cc: Perforce Change Reviews Subject: Re: PERFORCE change 20064 for review In-Reply-To: Your message of "Thu, 24 Oct 2002 15:17:28 EDT." From: "Brian F. Feldman" Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Thu, 24 Oct 2002 15:44:24 -0400 Sender: owner-p4-projects@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Robert Watson wrote: > Note that this is arguably incorrect for all policies but LOMAC, since > "fail stop" is the desired behavior for Biba, MLS, SELinux, and others. > This is why I changed the default for cow to off. We should look into a > way to provide both what LOMAC and the other policies need, perhaps by > having two entry points: one for the purpose of downgrading with COW, one > without. In particular, pay attention to cases like: > > LOMAC wants to downgrade write to read-only > Biba wants to remove write entirely > > The desired composition in this case is probably the Biba result. Well, note that nothing at all was enforced previously, and only LOMAC is capable of requesting downgrade at the moment, so this is effectively a LOMAC option, but in the wrong place :) I think the simple solution would be adding an int *dontCOW argument, and in policies which would like to revoke without COW something like: if (shouldrevoke(subj, obj)) { *perms &= ~VM_OBJECT_READ; if (I_should_not_COW) ++*dontCOW; } -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org <> bfeldman@tislabs.com \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe p4-projects" in the body of the message