netdev - Re: [PATCH net] netns: provide pure entropy for net_hash

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Date:   Thu, 28 Mar 2019 17:01:56 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        aksecurity@...il.com, benny@...kas.net, xemul@...nvz.org
Subject: Re: [PATCH net] netns: provide pure entropy for net_hash_mix()

From: Eric Dumazet <edumazet@...gle.com>
Date: Wed, 27 Mar 2019 08:21:30 -0700

> net_hash_mix() currently uses kernel address of a struct net,
> and is used in many places that could be used to reveal this
> address to a patient attacker, thus defeating KASLR, for
> the typical case (initial net namespace, &init_net is
> not dynamically allocated)
> 
> I believe the original implementation tried to avoid spending
> too many cycles in this function, but security comes first.
> 
> Also provide entropy regardless of CONFIG_NET_NS.
> 
> Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Amit Klein <aksecurity@...il.com>
> Reported-by: Benny Pinkas <benny@...kas.net>

Applied and queued up for -stable, thanks.