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Re: PID of client requirements
From: |
Thomas Bushnell, BSG |
Subject: |
Re: PID of client requirements |
Date: |
04 Nov 2002 10:12:59 -0800 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 |
Marcus Brinkmann <address@hidden> writes:
> It is clear that all POSIX programs will behave correctly given that
> semantic. What is not clear to me is if this is safe against malicious
> abuse.
>
> Let's start with an example. Imagine a privileged program that
> relies on the GETLK function to see what the current holder of a
> lock is and which kills that process in some situations. Then
> everybody who could take the lock would be able to have any process
> (including the root filesystem etc) killed just by providing the PID
> of that process when getting the lock.
Trusting the user to provide his pid is only half of the job when
signals are concerned. The second thing needed is a signal
authorization port which the user requests from the server, and which
the server will provide in the signal message. See, for example, how
this works for terminals.
> The general question is: Are there any potential security concerns
> about having the caller provide the PID? The above example is
> surely safe, because no untrusted party should have read or write
> permission. This seems to be generally true for record locks. I
> have not investigated the other application (shared memory and/or
> semaphores) where PID knowledge is required. Has anybody?
You are right to be thinking about this.
- PID of client requirements, Marcus Brinkmann, 2002/11/04
- Re: PID of client requirements,
Thomas Bushnell, BSG <=
- Re: PID of client requirements, Neal H. Walfield, 2002/11/04
- Re: PID of client requirements, Thomas Bushnell, BSG, 2002/11/05
- Re: PID of client requirements, Marcus Brinkmann, 2002/11/05
- Re: PID of client requirements, Thomas Bushnell, BSG, 2002/11/06
- Re: PID of client requirements, Marcus Brinkmann, 2002/11/06
- Re: PID of client requirements, Thomas Bushnell, BSG, 2002/11/07
- Re: PID of client requirements, Roland McGrath, 2002/11/07