linux-kernel - Re: [PATCH 4.19] inet: use bigger hash table for IP ID generation (backported to 4.19)

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Message-ID: <YNCwJqtKKCskB2Au@kroah.com>
Date:   Mon, 21 Jun 2021 17:28:38 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Amit Klein <aksecurity@...il.com>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        edumazet@...gle.com, w@....eu, davem@...emloft.net,
        netdev@...r.kernel.org
Subject: Re: [PATCH 4.19] inet: use bigger hash table for IP ID generation
 (backported to 4.19)

On Thu, Jun 17, 2021 at 01:19:18AM -0700, Amit Klein wrote:
> Subject: inet: use bigger hash table for IP ID generation (backported to 4.19)
> From: Amit Klein <aksecurity@...il.com>
> 
> This is a backport to 4.19 of the following patch, originally
> developed by Eric Dumazet.
> 
> In commit 73f156a6e8c1 ("inetpeer: get rid of ip_id_count")
> I used a very small hash table that could be abused
> by patient attackers to reveal sensitive information.
> 
> Switch to a dynamic sizing, depending on RAM size.
> 
> Typical big hosts will now use 128x more storage (2 MB)
> to get a similar increase in security and reduction
> of hash collisions.
> 
> As a bonus, use of alloc_large_system_hash() spreads
> allocated memory among all NUMA nodes.
> 
> Fixes: 73f156a6e8c1 ("inetpeer: get rid of ip_id_count")
> Reported-by: Amit Klein <aksecurity@...il.com>
> Cc: stable@...r.kernel.org
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Willy Tarreau <w@....eu>
> ---
>  net/ipv4/route.c | 42 ++++++++++++++++++++++++++++--------------
>  1 file changed, 28 insertions(+), 14 deletions(-)
> 
> (limited to 'net/ipv4/route.c')

I had to dig up what the upstream git commit id was for this, please
specify it next time :(

I've queued this, and the 4.14 version up.  Can you create a 4.4.y and
4.9.y version as well?

thanks,

greg k-h