netdev - Re: [PATCH] NETWORKING: avoid use IPCB in cipso_v4

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Message-ID: <CAHC9VhRys7Efm=aQqph2ug9c8Ryra9imEG66avjeEeY8QZWTqw@mail.gmail.com>
Date:   Fri, 15 Feb 2019 15:04:23 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     David Miller <davem@...emloft.net>
Cc:     s-nazarov@...dex.ru, netdev@...r.kernel.org,
        linux-security-module@...r.kernel.org, kuznet@....inr.ac.ru,
        yoshfuji@...ux-ipv6.org
Subject: Re: [PATCH] NETWORKING: avoid use IPCB in cipso_v4_error

On Fri, Feb 15, 2019 at 3:00 PM David Miller <davem@...emloft.net> wrote:
> From: Paul Moore <paul@...l-moore.com>
> Date: Fri, 15 Feb 2019 14:02:31 -0500
>
> > On Thu, Feb 14, 2019 at 11:43 AM David Miller <davem@...emloft.net> wrote:
> >> From: Nazarov Sergey <s-nazarov@...dex.ru>
> >> Date: Tue, 12 Feb 2019 18:10:03 +0300
> >>
> >> > Since cipso_v4_error might be called from different network stack layers, we can't safely use icmp_send there.
> >> > icmp_send copies IP options with ip_option_echo, which uses IPCB to take access to IP header compiled data.
> >> > But after commit 971f10ec ("tcp: better TCP_SKB_CB layout to reduce cache line misses"), IPCB can't be used
> >> > above IP layer.
> >> > This patch fixes the problem by creating in cipso_v4_error a local copy of compiled IP options and using it with
> >> > introduced __icmp_send function. This looks some overloaded, but in quite rare error conditions only.
> >> >
> >> > The original discussion is here:
> >> > https://lore.kernel.org/linux-security-module/16659801547571984@sas1-890ba5c2334a.qloud-c.yandex.net/
> >> >
> >> > Signed-off-by: Sergey Nazarov <s-nazarov@...dex.ru>
> >>
> >> This problem is not unique to Cipso, net/atm/clip.c's error handler
> >> has the same exact issue.
> >>
> >> I didn't scan more of the tree, there are probably a couple more
> >> locations as well.
> >
> > David, are you happy with Sergey's solution as a fix for this?
> >
> > If so, would you prefer a respin of this patch to apply the to the
> > other broken callers (e.g. net/atm/clip.c), or would you rather merge
> > this patch and deal with the other callers in separate patches?
>
> I'd like the other broken callers to be handled.

Sergey, do you think you could fix the other callers too, or do you
want some help with that?

-- 
paul moore
www.paul-moore.com