From owner-freebsd-hackers@FreeBSD.ORG Fri Aug 22 02:52:02 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A6E1516A4BF for ; Fri, 22 Aug 2003 02:52:02 -0700 (PDT) Received: from milla.ask33.net (milla.ask33.net [217.197.166.60]) by mx1.FreeBSD.org (Postfix) with ESMTP id CE0CD43FBF for ; Fri, 22 Aug 2003 02:52:01 -0700 (PDT) (envelope-from nick@milla.ask33.net) Received: by milla.ask33.net (Postfix, from userid 1001) id 97EC93ABB3F; Fri, 22 Aug 2003 11:52:55 +0200 (CEST) Date: Fri, 22 Aug 2003 11:52:55 +0200 From: Pawel Jakub Dawidek To: Peter Jeremy Message-ID: <20030822095255.GO47959@garage.freebsd.pl> References: <20030817181315.GL55671@episec.com> <20030821065854.GA11586@dan.emsphone.com> <20030821125028.GY55671@episec.com> <20030821162156.GL47959@garage.freebsd.pl> <20030821170915.GZ55671@episec.com> <20030821204403.GN47959@garage.freebsd.pl> <20030822074023.GA85534@cirb503493.alcatel.com.au> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-md5; protocol="application/pgp-signature"; boundary="FrxVhwK/bNRjN48l" Content-Disposition: inline In-Reply-To: <20030822074023.GA85534@cirb503493.alcatel.com.au> X-PGP-Key-URL: http://garage.freebsd.pl/jules.asc X-OS: FreeBSD 4.8-RELEASE-p3 i386 X-URL: http://garage.freebsd.pl User-Agent: Mutt/1.5.1i cc: flowpriv@episec.com cc: freebsd-hackers@freebsd.org cc: ari Subject: Re: [future patch] dropping user privileges on demand X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Aug 2003 09:52:02 -0000 --FrxVhwK/bNRjN48l Content-Type: text/plain; charset=iso-8859-2 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Aug 22, 2003 at 05:40:23PM +1000, Peter Jeremy wrote: +> Unless 'syscall' can be evaluated at compile time, this approach adds +> overhead whereever it is used - and the overhead gets worse as the +> number of system calls in the set increases. A particular problem is +> that the overhead is worst for system calls that aren't caught (in the +> above, the overhead for open() is trivial but write() would need to go +> through each of the tests). A bit-vector provides constant overhead +> but it's still fairly expensive unless the relevant parts of the vector +> are already cached. You are wrong. In CerbNG, you decide in rules which syscalls should be catched and which n= ot. And syscalls like read(2) and write(2) are never catched, because it is just useless. The most expensive policy in syscalls catching is openssh - it is monitoring 21 syscalls, but most of policies use only few syscalls. Of course there is overhead, but I haven't heard about security feature that speeds up system. The only thing we can do, is to decrease overhead. --=20 Pawel Jakub Dawidek pawel@dawidek.net UNIX Systems Programmer/Administrator http://garage.freebsd.pl Am I Evil? Yes, I Am! http://cerber.sourceforge.net --FrxVhwK/bNRjN48l Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (FreeBSD) iQCVAwUBP0Xn9z/PhmMH/Mf1AQFVywP/bn9yXjZBhKFFrEQJgtyyUqypF/PWJrx6 BWUBfv6VYeE6N40vuI8k4rq/1lUCdtmhrhi8aGOGwrBuGWs2SsziocquB3SI5N9M kpCPGOejbGaDInlSEgtLg6VanmR+51BCsDiFZvtw6ewz2j/zCTddV4Zglwv80a1+ QBvhEJn4Xkk= =6LMW -----END PGP SIGNATURE----- --FrxVhwK/bNRjN48l--