Messages in this thread | | | Date | Wed, 16 Nov 2011 10:19:23 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH 0/4] Checkpoint/Restore: Show in proc IDs of objects that can be shared between tasks |
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On Tue, Nov 15, 2011 at 09:44:27PM -0800, Matt Helsley wrote: ... > > > > The object address is XOR-ed with a "random" value of the same size and then > > shown in proc. Providing this poison is not leaked into the userspace then > > ID seem to be safe. > > Really? There's no way to quickly derive the random number from known > allocation patterns and thereby break the obfuscation scheme? > To start we can note that the low N bits are directly exposed in the ID > of anything that requires 2^N-byte alignment. > > I think it's really a question of whether the high order bits can be derived. >
Good point. I suppose we might use 2 random numbers here, one for xor and second to shuffle bits.
> And of course the random number only needs to be derived once per boot > before it reveals the address of everything with an ID.
Cyrill
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