From: nhorman@mail•tuxdriver.com
To: "Eric Dumazet" <eric.dumazet@gmail•com>,
"Neil Horman" <nhorman@tuxdriver•com>
Cc: netdev@vger•kernel.org, davem@davemloft•net,
kuznet@ms2•inr.ac.ru, jmorris@namei•org, yoshfuji@linux-ipv6•org,
kaber@trash•net
Subject: Re: [PATCH] ipv4: remove ip_rt_secret timer (v2)
Date: Thu, 6 May 2010 20:02:06 -0400 [thread overview]
Message-ID: <E1OAB1B-0002ar-Dp@smtp.tuxdriver.com> (raw)
In-Reply-To: <1273180085.2222.33.camel@edumazet-laptop>
On Thu, 6 May 2010 17:08:05 -0400, Eric Dumazet wrote:
> Le jeudi 06 mai 2010 à 16:29 -0400, Neil Horman a écrit :
> > Version 2 of this patch, taking Erics comment about making the rt_genid non-zero
> > when a netns is created. This makes sense, and helps prevent attackers from
> > guessing our initial secret value
> >
> >
> >
> > A while back there was a discussion regarding the rt_secret_interval timer.
> > Given that we've had the ability to do emergency route cache rebuilds for awhile
> > now, based on a statistical anal> > cache, the use of the flush timer is somewhat redundant. This patch removes the
> > rt_secret_interval sysctl, allowing us to rely solely on the statistical
> > analysis mechanism to determine the need for route cache flushes.
> >
> > Signed-off-by: Neil Horman <nhorman@tuxdriver•com>
> >
>
> > -
> > -static __net_init int rt_secret_timer_init(struct net *net)
> > +static __net_init int rt_genid_init(struct net *net)
> > {
> > - atomic_set(&net->ipv4.rt_genid,
> > - (int) ((num_physpages ^ (num_physpages>>8)) ^
> > - (jiffies ^ (jiffies >> 7))));
> > -
>
>
> > + /*
> > + * This just serves to start off each new net namespace
> > + * with a non-zero rt_genid value, making it harder to guess
> > + */
> > + rt_cache_invalidate(net);
> > return 0;
> > }
> >
>
> I am _sorry_ to be such a paranoiac guy.
>
Don't be sorry, I think your concern is valid, I just don't want to keep old code around when
> Could you please feed more than 8 bits here ?
>
> like :
>
> get_random_bytes(&net->ipv4.rt_genid, sizeof(net->ipv4.rt_genid));
>
Sure, I'm good with that. I'm not at my desk right now, but ill do that in the morning.
> There is no need to comment this in the code, this kind of rnd init is
> very common in net tree.
>
Ok, copy that, ill fix that up at the same time.
Thanks & regards
Neil
>
>
>
>
>
next prev parent reply other threads:[~2010-05-07 0:02 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-06 17:16 [PATCH] ipv4: remove ip_rt_secret timer Neil Horman
2010-05-06 17:32 ` Eric Dumazet
2010-05-06 18:02 ` Neil Horman
2010-05-06 18:33 ` Eric Dumazet
2010-05-06 19:54 ` Neil Horman
2010-05-06 20:10 ` Eric Dumazet
2010-05-06 20:25 ` Neil Horman
2010-05-06 20:29 ` [PATCH] ipv4: remove ip_rt_secret timer (v2) Neil Horman
2010-05-06 21:08 ` Eric Dumazet
2010-05-07 0:02 ` nhorman [this message]
2010-05-07 19:55 ` [PATCH] ipv4: remove ip_rt_secret timer (v3) Neil Horman
2010-05-07 21:04 ` Eric Dumazet
2010-05-07 23:15 ` Neil Horman
2010-05-08 1:01 ` [PATCH] ipv4: remove ip_rt_secret timer (v4) Neil Horman
2010-05-08 6:36 ` Eric Dumazet
2010-05-08 8:58 ` David Miller
2010-05-08 12:54 ` Neil Horman
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