From: David Ahern <dsahern@gmail•com>
To: Eric Dumazet <eric.dumazet@gmail•com>,
"David S . Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>
Cc: netdev <netdev@vger•kernel.org>,
Eric Dumazet <edumazet@google•com>, Willy Tarreau <w@1wt•eu>,
Keyu Man <kman001@ucr•edu>, David Ahern <dsahern@kernel•org>,
Wei Wang <weiwan@google•com>, Martin KaFai Lau <kafai@fb•com>
Subject: Re: [PATCH net 1/2] ipv6: make exception cache less predictible
Date: Sun, 29 Aug 2021 17:39:17 -0700 [thread overview]
Message-ID: <7c8bdee5-66cf-996e-eaea-db3aee6f0d5f@gmail.com> (raw)
In-Reply-To: <20210829221615.2057201-2-eric.dumazet@gmail.com>
On 8/29/21 3:16 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google•com>
>
> Even after commit 4785305c05b2 ("ipv6: use siphash in rt6_exception_hash()"),
> an attacker can still use brute force to learn some secrets from a victim
> linux host.
>
> One way to defeat these attacks is to make the max depth of the hash
> table bucket a random value.
>
> Before this patch, each bucket of the hash table used to store exceptions
> could contain 6 items under attack.
>
> After the patch, each bucket would contains a random number of items,
> between 6 and 10. The attacker can no longer infer secrets.
>
> This is slightly increasing memory size used by the hash table,
> we do not expect this to be a problem.
>
> Following patch is dealing with the same issue in IPv4.
>
> Fixes: 35732d01fe31 ("ipv6: introduce a hash table to store dst cache")
> Signed-off-by: Eric Dumazet <edumazet@google•com>
> Reported-by: Keyu Man <kman001@ucr•edu>
> Cc: Wei Wang <weiwan@google•com>
> Cc: Martin KaFai Lau <kafai@fb•com>
> ---
> net/ipv6/route.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
Reviewed-by: David Ahern <dsahern@kernel•org>
next prev parent reply other threads:[~2021-08-30 0:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-29 22:16 [PATCH net 0/2] inet: make exception handling less predictible Eric Dumazet
2021-08-29 22:16 ` [PATCH net 1/2] ipv6: make exception cache " Eric Dumazet
2021-08-30 0:39 ` David Ahern [this message]
2021-08-30 15:54 ` Wei Wang
2021-08-29 22:16 ` [PATCH net 2/2] ipv4: " Eric Dumazet
2021-08-30 0:40 ` David Ahern
2021-08-30 18:04 ` [PATCH net 0/2] inet: make exception handling " Keyu Man
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