On Thu, Oct 03, 2013 at 11:06:58PM +0000, Dilger, Andreas wrote:
>
> The Lustre cfs_get_random_bytes() incorporates (via cfs_rand()) a seed
> which
> also hashes in the addresses from any network interfaces that are
> configured.
> Conversely, cfs_rand() also is seeded at startup from get_random_bytes() in
> case a hardware RNG is available. This ensures even with identical initial
> conditions cfs_get_random_bytes() gets a different random stream on each
> node.
With modern kernels, the /dev/random driver has the
add_device_randomness() interface which is used to mix in
personalization information, which includes the network MAC address.
So that particular concern should be covered without the hack of
mixing in cfs_rand().
> I'm not against cleaning this up, if there is some mechanism for the
> startup code to add in the node interface addresses into the entropy
> pool, and this is also used to perturb the prandom_u32() sequence
> after that point.
That's handled too, via the late initcall prandom_reseed().
Cheers,
- Ted
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