linux-kernel - Re: [GIT PULL] x86/iopl changes for v5.5

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHk-=whswxd9b0A9Sr5YhjcGbA0WKrB8Rrtx89PLKeP6RdKT3A@mail.gmail.com>
Date:   Tue, 26 Nov 2019 11:33:37 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [GIT PULL] x86/iopl changes for v5.5

On Mon, Nov 25, 2019 at 8:16 AM Ingo Molnar <mingo@...nel.org> wrote:
>
> This tree implements a nice simplification of the iopl and ioperm code
> that Thomas Gleixner discovered: we can implement the IO privilege
> features of the iopl system call by using the IO permission bitmap in
> permissive mode, while trapping CLI/STI/POPF/PUSHF uses in user-space if
> they change the interrupt flag.

I've pulled it.

But do we have a test for something like this:

   ioperm(.. limited set of ports..)
   access that limited set.

   special_sequence() {
       iopl(3);
       access some extended set
       iopl(0)
   }

   go back to access the limited set again

because there's subtle interactions with people using *both* iopl()
and ioperm() and switching between the two. Historically you could
trivially do the above, because they are entirely independent
operations. Does it still work?

Too busy/lazy to check myself.

              Linus