From: Adam Jackson <ajax@redhat.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: linux-kernel@vger.kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org
Subject: Re: [PATCH 1/2] char/mem: Add /dev/io (v2)
Date: Tue, 07 Feb 2012 19:38:47 -0500 [thread overview]
Message-ID: <4F31C417.30502@redhat.com> (raw)
In-Reply-To: <20120208001724.7e5c7be4@pyramind.ukuu.org.uk>
On 2/7/12 7:17 PM, Alan Cox wrote:
> On Tue, 7 Feb 2012 18:39:45 -0500
> Adam Jackson<ajax@redhat.com> wrote:
>
>> This is like /dev/port except not broken. /dev/port will translate all
>> read/write into inb/outb streams, which is wrong since hardware can and
>> does care about cycle size. /dev/io will only allow 1, 2, or 4 byte
>> access, and will translate that into the appropriate bus cycle size.
>
> From a security perspective /dev/[k][mem is a dumb bit of ancient Unix
> history we'd dearly like to kill off. /dev/port is a similar early PC
> unixism that wants to go the same way. /dev/io just adds another horror
> to the pile.
>
> Please do the decent thing, stop using /dev/mem and /dev/port for
> anything. If you need to access an I/O device make it properly visible
> via the kernel only for the ports and in a manner that is safe.
Yeah, I'll be sure to do that right as soon as I can stop supporting the
vesa driver. Until that time I don't really have any choice but to
expose the whole of I/O port space, since I have no idea what the video
BIOS is going to touch.
I don't disagree with wanting to limit access to these services, but
/dev/io is at least somewhat containable, whereas iopl is insane.
- ajax
next prev parent reply other threads:[~2012-02-08 0:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-07 14:11 [PATCH 1/2] char/mem: Add /dev/io Adam Jackson
2012-02-07 14:11 ` [PATCH 2/2] char/mem: Schedule /dev/port for removal Adam Jackson
2012-02-07 23:39 ` [PATCH 1/2] char/mem: Add /dev/io (v2) Adam Jackson
2012-02-08 0:17 ` Alan Cox
2012-02-08 0:38 ` Adam Jackson [this message]
2012-02-08 9:26 ` Alan Cox
2012-02-08 14:03 ` Adam Jackson
2012-02-08 14:32 ` Alan Cox
2012-02-08 23:16 ` Adam Jackson
2012-02-09 11:27 ` Alan Cox
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