Message-ID: <5552427D.9070806@gmail.com>
Date: Tue, 12 May 2015 14:12:13 -0400
From: Austin S Hemmelgarn <ahferroin7@gmail.com>
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To: Alex Henrie <alexhenrie24@gmail.com>
CC: Arjan van de Ven <arjanvandeven@gmail.com>, Ingo Molnar <mingo@kernel.org>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Kees Cook <keescook@chromium.org>, "H . Peter Anvin" <hpa@zytor.com>,
        Doug Johnson <dougvj@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Tyler Hicks <tyhicks@canonical.com>,
        Al Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arjan van de Ven <arjan@infradead.org>,
        Denys Vlasenko <dvlasenk@redhat.com>, Brian Gerst <brgerst@gmail.com>
Subject: Re: [PATCH v2] x86: Preserve iopl on fork and execve
References: <1431387505-13410-1-git-send-email-alexhenrie24@gmail.com> <20150512064032.GA25097@gmail.com> <CADyApD3Kom234GhvNdxTiF8xpUdqp9cLp8TuGLTkrQ=Z3ESkfg@mail.gmail.com> <CADyApD2-J07zg7gfa+LrFbHB_p2gN5k2P+x7OTCW1_rybTkdQA@mail.gmail.com> <5552209C.501@gmail.com> <CAMMLpeR-JZTTLGY6yovnHdz7esAvRMrMeSRpWAKyvgenREM24g@mail.gmail.com>
In-Reply-To: <CAMMLpeR-JZTTLGY6yovnHdz7esAvRMrMeSRpWAKyvgenREM24g@mail.gmail.com>
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On 2015-05-12 14:05, Alex Henrie wrote:
> 2015-05-12 9:47 GMT-06:00 Austin S Hemmelgarn <ahferroin7@gmail.com>:
>> On 2015-05-12 11:25, Arjan van de Ven wrote:
>>> If you look at a modern linux distro, nothing should need/use iopl an=
d
>>> co anymore, so maybe an interesting
>>> question is if we can stick these behind a CONFIG_ option (default on=

>>> of course for compatibility)... just like
>>> some of the /dev/mem like things are now hidable for folks who know
>>> they don't need them.
>>
>> Personally, I _really_ like this idea.  The only thing I know of on an=
y
>> modern distro that even considers using ioperm is hwclock, and it only=
 does
>> so if it can't access the RTC through other means (and if you have an =
RTC,
>> you really should have the /dev interface enabled).
>
> Removing iopl might be OK. Removing ioperm would break my use case of
> legacy code that needs direct access to the parallel port.
>
> -Alex
>
The discussion isn't about outright removing them, just providing a=20
config option to disable them.  It might be a good idea though to=20
provide separate config options for each of iopl() and ioperm(), as=20
iopl() is more dangerous, and ioperm() is more widely used, and people=20
may need one but not want to have the other.


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