Re: [patch 7/8] fdmap v2 - implement sys_socket2

[Al Viro <viro@ftp.linux.org.uk>]

On Sat, Jun 09, 2007 at 09:26:34AM -0700, Ulrich Drepper wrote:
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> Al Viro wrote:
> > So which code is supposed to do that open/write in your example?  Library?
> > Unmodified application?  Application specifically modified to make *that*
> > open() randomized?
> 
> Why should that matter?  All of the above.

I asked for real-world example.  Can I have one, please?

> In whatever way you look at it, there currently is a problem which
> cannot be solved except with truly horrible, horrible hack (open N
> descriptors and randomly select one to use; yep, horrible, I said so).

That's simply not true.  On the current kernel nothing stops you from e.g.
picking a random number and using F_DUPFD.  Voila - there's your randomized
descriptor.  Portable to earlier kernels.

Moreover, nonsense^H^H^Hq_fd() can be implemented in userland just fine
if we allow F_DUPFD to arbitrary number - just pass it a random one *or*
base chosen like davedel is doing (constant + 20bit random chosen at start
time).
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