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

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Date:   Fri, 18 Jan 2019 19:34:41 +0300
From:   Nazarov Sergey <s-nazarov@...dex.ru>
To:     Paul Moore <paul@...l-moore.com>
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.

Hi, Paul!
I don't like this. As you said, fix any calls to icmp_send is a trivial.
But in cipso_v4_optptr, we repeating the work already done, and in cipso_v4_error
we will need to do even more again. Any code, working with IP header data on several
levels of TCP/IP stack need to do this again and again. Is looks too overloaded!
In my opinion, this is a problem of TCP/IP stack design, comes from standing
compiled IP header data in different places at different stack layers.
May be better to add some flag or pointer to struct sk_buff?
But, I think, we need netdev developers advice for this.
Regards, Sergey.

18.01.2019, 17:53, "Paul Moore" <paul@...l-moore.com>:
> On Tue, Jan 15, 2019 at 2:52 PM Paul Moore <paul@...l-moore.com> wrote:
>
> It's been a few days now with no comments from the netdev folks, so I
> think it's probably best to start putting together a RFC patch for
> review/comment. Nazarov, would you like to do that? If not, that's
> okay, just let me know.
>
> I'm still concerned about calling ip_options_compile() in icmp_send()
> and I'm thinking we might be better off to add a new ip_options
> parameter to icmp_send(); if the parameter is NULL we behave as we do
> today, but if it is non-NULL we use the given ip_options parameter in
> place of calling ip_options_echo(). With that change in place, we
> would need to update cipso_v4_error() to do the extra work of calling
> ip_options_compile() and __ip_options_echo(). There looks to be maybe
> a dozen (or two?) existing icmp_send() callers, but it should be
> pretty trivial to update them to pass NULL for the new parameter.
>
> What do you think?
>
>
> --
> paul moore
> www.paul-moore.com