netdev - Re: SO_PEERSEC protections in sk

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Date:   Mon, 10 Oct 2022 09:19:28 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     David Laight <David.Laight@...lab.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Martin KaFai Lau <martin.lau@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        LSM List <linux-security-module@...r.kernel.org>,
        "selinux@...r.kernel.org" <selinux@...r.kernel.org>
Subject: Re: SO_PEERSEC protections in sk_getsockopt()?

On Mon, Oct 10, 2022 at 8:54 AM David Laight <David.Laight@...lab.com> wrote:
> From: Alexei Starovoitov
> > Sent: 07 October 2022 22:55
> ....
> > Not easy at all.
> > There is only way place in the whole kernel that does:
> >                 return sk_getsockopt(sk, SOL_SOCKET, optname,
> >                                      KERNEL_SOCKPTR(optval),
> >                                      KERNEL_SOCKPTR(optlen));
>
> Until I add change my out of tree driver to work with
> the new code.
> (Although it actually needs to do a getsockopt into SCTP.)
>
> I didn't spot the change to sk_getsockopt() going though.
> But KERNEL_SOCKPTR() is really the wrong function/type
> for the length.
> It would be much safer to have a struct with two members,
> one an __user pointer and one a kernel pointer both to
> socklen_t.

Yes, agreed.

> It isn't really ideal for the buffer pointer either.
> That started as a single field (assuming the caller
> has verified the user/kernel status), then the is_kernel
> field was added for architectures where user/kernel
> addresses use the same values.
> Then a horrid bug (forgotten where) forced the is_kernel
> field be used everywhere.
> Again a structure with two pointers would be much safer.

Any chance you have plans to work on this David?

-- 
paul-moore.com