linux-kernel - Re: [patch 5/9] x86/ioport: Reduce ioperm impact for sane usage further

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Message-ID: <20191107165752.GD15642@1wt.eu>
Date:   Thu, 7 Nov 2019 17:57:52 +0100
From:   Willy Tarreau <w@....eu>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     hpa@...or.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Juergen Gross <jgross@...e.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [patch 5/9] x86/ioport: Reduce ioperm impact for sane usage
 further

On Thu, Nov 07, 2019 at 10:45:09AM -0600, Eric W. Biederman wrote:
> Further a quick look shows that dosemu uses ioperm in a fine grained
> manner.  From memory it would allow a handful of ports to allow directly
> accessing a device and depended on the rest of the port accesses to be
> disallowed so it could trap and emulate them.
> 
> So yes I do believe making ioperm ioperm(all) will break userspace.

OK, and I must confess I almost forgot about dosemu, that's a good point!

Thanks,
Willy