From owner-freebsd-arch Sun Aug 18 13: 1: 9 2002 Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C970E37B400 for ; Sun, 18 Aug 2002 13:01:07 -0700 (PDT) Received: from salmon.maths.tcd.ie (salmon.maths.tcd.ie [134.226.81.11]) by mx1.FreeBSD.org (Postfix) with SMTP id 8CE9543E3B for ; Sun, 18 Aug 2002 13:01:06 -0700 (PDT) (envelope-from iedowse@maths.tcd.ie) Received: from walton.maths.tcd.ie by salmon.maths.tcd.ie with SMTP id ; 18 Aug 2002 21:01:05 +0100 (BST) To: Bruce Evans Cc: arch@FreeBSD.ORG Subject: Re: Solving the stack gap issue In-Reply-To: Your message of "Mon, 19 Aug 2002 05:31:54 +1000." <20020819045750.C16172-100000@gamplex.bde.org> Date: Sun, 18 Aug 2002 21:01:03 +0100 From: Ian Dowse Message-ID: <200208182101.aa62911@salmon.maths.tcd.ie> Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <20020819045750.C16172-100000@gamplex.bde.org>, Bruce Evans writes: > >The discussion was in response to axeing an undead version of >trap_pfault(). This version was intended to be used to drop support >for direct accesses. Thanks, yes, I remember now. Of course the detection of kernel accesses to user memory in trap_pfault will only trigger on unmapped addresses. To be useful for detecting this kernel code we would ideally want a way of catching all accesses, even if turning on that detection had a big performance penalty. >Even copying in pathnames is not such a good idea then. The copying >would have to be done in several compat opens, not to mention in all >other syscalls that take pathnames, instead of only in namei(). The compat modules generally want to munge paths by prepending /compat/linux for example, so all syscalls that take path arguments need to accept a kernel-space string (unless we move the path munging into namei). It is very easy to handle paths in the sys_*() functions anyway, as the uio_seg argument can be passed straight into NDINIT(). Ian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message