Messages in this thread | | | Date | Sun, 03 Jun 2007 13:46:21 -0700 | From | Ulrich Drepper <> | Subject | Re: [patch 2/2] ufd v1 - use unsequential O(1) fdmap |
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Davide Libenzi wrote: >> If randomizing each allocator is too expensive then randomize at the >> very least the number of the first descriptor you give out. > > Can you tell me how this can be a problem, and in which way making a > random thing would help?
In attacking an application every bit of known data can be used in an exploit. Be it something as simple as having a predetermined value at a certain point in the program since it loaded a file descriptor into a register.
But what I'm mostly thinking about is the case where I/O could be redirected. The intruding program could call dup2() and suddenly the program wanting to write a password to disk could be directed to send it over a socket. One could imagine countless such attacks.
I don't say such an attack exists today. But this is no reason to not implement these extra security measures. The cost of a randomized star base (offset from 2^30) should be zero.
- -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux)
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