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Date:      Fri, 17 Oct 2003 10:15:12 -0400
From:      David Gilbert <dgilbert@dclg.ca>
To:        Samy Al Bahra <samy@kerneled.com>
Cc:        David Gilbert <dgilbert@dclg.ca>
Subject:   Re: On-line judgment kernel module
Message-ID:  <16271.63856.24959.164434@canoe.dclg.ca>
In-Reply-To: <20031017132255.197cd7b8.samy@kerneled.com>
References:  <1197083983.20031009074645@inbox.ru> <16271.7039.150262.159805@canoe.dclg.ca> <20031017132255.197cd7b8.samy@kerneled.com>

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>>>>> "Samy" == Samy Al Bahra <samy@kerneled.com> writes:

Samy> On Thu, 16 Oct 2003 18:28:15 -0400 David Gilbert
Samy> <dgilbert@dclg.ca> wrote:

>> As you conjecture, a syscall-less or syscall-restricted environment
>> *should* be safe ... if your syscall changes are bulletproof
>> *_and_* the rest of the runtime environment is bulletproof.
Samy> Good system call policies are a WONDERFUL feature at a system
Samy> administrator's hands. There is no such thing as a syscall-less
Samy> environment but only a restricted (either at the same layer as
Samy> the system calls or above in terms of code path).

Still... it would seem to me to be safer to use a complete emulation
environment than risk getting everything else right.

>> Isn't a syscall required to finish off exit()?
Samy> Yes, consult kern_exit.c How is this related to the discussion
Samy> though? The fact is, most people would not even want to TOUCH
Samy> sys_exit and friends since there are no real security advantages
Samy> there. In otherwords, an exit system call remains completely the
Samy> same.

Ah, well ... I was understanding that origional email wanted a
syscall-less environment and was just further arguing the point.

Dave.

-- 
============================================================================
|David Gilbert, Independent Contractor.       | Two things can only be     |
|Mail:       dave@daveg.ca                    |  equal if and only if they |
|http://daveg.ca                              |   are precisely opposite.  |
=========================================================GLO================



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