netdev - Re: Kernel memory corruption in CIPSO labeled TCP packets processing.

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Date:   Mon, 28 Jan 2019 17:18:41 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Nazarov Sergey <s-nazarov@...dex.ru>
Cc:     "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "selinux@...r.kernel.org" <selinux@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: Kernel memory corruption in CIPSO labeled TCP packets processing.

On Mon, Jan 28, 2019 at 8:10 AM Nazarov Sergey <s-nazarov@...dex.ru> wrote:
> 25.01.2019, 19:46, "Paul Moore" <paul@...l-moore.com>:
> > Hmm, I think the above calculation should take into account the actual
> > length of the IP options, and not just the max size (calculate it
> > based on iphdr->ihl).
> >
> > Beyond that fix, I think it's time to put together a proper patchset
> > and post it to the lists for formal review/merging.
> >
> > Thanks for your work on this.
> >
> > --
> > paul moore
> > www.paul-moore.com
>
> Where we can take actual IP options length? Sorry, I'm not so familiar with linux network stack.

I'm the one who needs to apologize; you're doing it correctly.  Not
sure what I was thinking there, sorry about that.

> And also, ip_options_compile could change IP options data (SSRR, LSRR, RR, TIMESTAMP options),
> so, we can't use ip_options_compile again for these options. Am I right?

If we don't pass a skb into ip_options_compile(), meaning both "skb"
and "rt" will be NULL, then I don't believe the option data will
change.  Am I missing something?

-- 
paul moore
www.paul-moore.com