Re: [RFC/PATCH] revoke/frevoke system calls V2

[Daniel Jacobowitz]

On Mon, Aug 07, 2006 at 10:52:59PM +0000, David Wagner wrote:
> I'm still trying to understand the semantics of this proposed
> frevoke() implementation.  Can an attacker use this to forcibly
> close some other processes' file descriptor?  Suppose the target
> process has fd 0 open and the attacker revokes the file corresponding
> to fd 0; what is the state of fd 0 in the target process?  Is it
> closed?  If the target process then open()s another file, does it
> get bound to fd 0?  (Recall that open() always binds to the lowest
> unused fd.)  If the answers are "yes", then the security consequences
> seem very scary.

No, that's already been answered at least once.  The file remains open,
but returns EBADF on various operations.

-- 
Daniel Jacobowitz
CodeSourcery
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