Messages in this thread | | | Date | Sat, 9 Jun 2007 10:04:19 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: [patch 7/8] fdmap v2 - implement sys_socket2 |
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On Sat, 9 Jun 2007, Al Viro wrote:
> 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).
That does not work. Or better, it works but it forces *huge* fdtables to be created. To do that, you need "start" to be over NR_FILE, and this creates an fdtable bigger than NR_FILE ((pointer-size + a-few-bits) * NR_FILE) propagated down to every app you fork.
- Davide
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