From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161009AbWGUHpn (ORCPT ); Fri, 21 Jul 2006 03:45:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161013AbWGUHpn (ORCPT ); Fri, 21 Jul 2006 03:45:43 -0400 Received: from moutng.kundenserver.de ([212.227.126.187]:59591 "EHLO moutng.kundenserver.de") by vger.kernel.org with ESMTP id S1161014AbWGUHpm (ORCPT ); Fri, 21 Jul 2006 03:45:42 -0400 From: Bodo Eggert <7eggert@elstempel.de> Subject: Re: why is intercepting system calls considerred bad? To: Joshua Hudson , Irfan Habib , linux-kernel@vger.kernel.org Reply-To: 7eggert@gmx.de Date: Fri, 21 Jul 2006 09:44:46 +0200 References: <6AVr2-6FS-3@gated-at.bofh.it> <6AVU0-7fw-3@gated-at.bofh.it> User-Agent: KNode/0.7.2 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8Bit X-Troll: Tanz Message-Id: X-be10.7eggert.dyndns.org-MailScanner-Information: See www.mailscanner.info for information X-be10.7eggert.dyndns.org-MailScanner: Found to be clean X-be10.7eggert.dyndns.org-MailScanner-From: 7eggert@elstempel.de X-Provags-ID: kundenserver.de abuse@kundenserver.de login:9b3b2cc444a07783f194c895a09f1de9 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Joshua Hudson wrote: > On 7/20/06, Irfan Habib wrote: >> I recently met a kernel janitor, who told me that intercepting system >> calls is undesirable, why? > > I'll bite. > > You intercept. Somebody else intercepts. You want to stop intercepting. Use a double-linked list. Having a mechanism to intercept syscalls will slow down syscall processing, and there was no legit user in the history of linux. If you need something like that, there is ptrace. > For this reason, anybody who intercepts a system call must be compiled > in, No, but they may need to be compiled in for other reasons. > and if two intercept the same system call, than the link order > dictates behavior. > > Obviously not desirable. ACK. -- Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF verbreiteten Lügen zu sabotieren. http://david.woodhou.se/why-not-spf.html