From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261576AbUDHEIV (ORCPT ); Thu, 8 Apr 2004 00:08:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261580AbUDHEIU (ORCPT ); Thu, 8 Apr 2004 00:08:20 -0400 Received: from web40508.mail.yahoo.com ([66.218.78.125]:58961 "HELO web40508.mail.yahoo.com") by vger.kernel.org with SMTP id S261576AbUDHEIE (ORCPT ); Thu, 8 Apr 2004 00:08:04 -0400 Message-ID: <20040408040756.95337.qmail@web40508.mail.yahoo.com> Date: Wed, 7 Apr 2004 21:07:56 -0700 (PDT) From: Sergiy Lozovsky Subject: Re: kernel stack challenge To: Horst von Brand Cc: Linux Kernel Mailing List In-Reply-To: <200404080243.i382hG6K003775@eeyore.valparaiso.cl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Horst von Brand wrote: > Sergiy Lozovsky said: > > --- Horst von Brand wrote: > > [...] > > > > And then there is the technology of _inventing_ > a > > > language tailored to the > > > task at hand... even better than your list of > > > high-level languages. > > > I started exactly with that. I found out shortly > that > > have no idea of functionality needed for such kind > of > > system. > > Come back when you have found out. Sorry. I live in the real world. In 1999 I had servers to protect. One of them was hacked and I started to look for tools which could protect servers. I found NOTHING. (there were some Intrusion Detection Systems, which would alert you when your server was ALREADY hacked - it was completely unacceptable for me). So I created VXE. Problem was solved. I could not sit and think about some perfect design while my servers were in the net unprotected, it's too expensive. Speed is not most important for me. If I have fast but unprotected server - it is of no use for me. > > > It was clear that requirments for this > sytem > > can change rapidly. > > I would not trust anything with "rapidly changing > requirements" as security > infrastructure. VXE worked for me. It was much better than nothing. > > Only general purpose language > can > > address this problem (if we want to save time of > > development and introduction of new security > models). > > A security model has to be exhaustively scrutinized, > proved correct and > complete, and well-tested. The implementation > language is completely > irrelevant, the hard work is _not_ programming. > > > Example. Current security policies are 'static'. > > In what sense? Actually one 'dynamic' feature is implemented in VXE. In ordinary system resource has permissions which allows access or not. For higher security VXE can count number of allowed accesses. For example, we are securing POP server. We allow it to open /etc/passwd, /etc/shadow for reading only once (counter is 1). So, if hacker breaks to POP server after it opened /etc/passwd - there is no way hacker can open this file. Another 'dynamic' feature is changing policy on the fly. For now POP server can access all mailboxes in /var/spool/mail - it's easy to add ability to modify policy. After POP server authorized user it changes it's UID - at that point we can set access to /var/spool/mail/user_1 only. So POPD couldn't access other files in all mailbox directories. > > > It > > seems, that it would be nice to have 'dynamic' > > policies (with support from security model). > > Again, what does this mean? > > > Now, > > policy describes resources available for > subsystem. > > No... > > > > It > > may be useful to limit the sequence of access to > > resources - 'behaviour' of subsystem. I'm not sure > if > > I want to implement that right away, but there is > > commercial system which does exactly that already > (it > > was created later than VXE). > > What is the use of restricting access sequences? If > sequence A, B, C is > forbidden, chances are that C, B, A (or any of the > other 4 permutations) > will give an attacker exactly what he wants. VXE can have counters assigned to syscall parameters. More sophisticated way is to have determined sequence of syscalls. So, if hackers broke in the system (sendmail for example) he can just follow logic of the system - do the work of sendmail for you :-) I can't say how easy to use this, but the company (my competitors :-) which created this is entercept.com - it seems, that they were very successful - I went to their site right now and was redirected to Network Associates - they were bought out, my guess. Serge. __________________________________ Do you Yahoo!? Yahoo! Small Business $15K Web Design Giveaway http://promotions.yahoo.com/design_giveaway/