RE: Future Linux devel. Kernels

From: Simon Richter (
Date: Mon May 08 2000 - 13:51:17 EST

On Mon, 8 May 2000, Igmar Palsenberg wrote:

[Securing system binaries with securelevels]

> I think that directly accessing /dev/hd or sd should also fall under the
> restricted operation..

The securelevels spec also states this. Readonly access in singleuser
mode, No access in multiuser.

> However, I think this breaks programs such as dump

dumping a device directly is evil, as the filesystem metadata can change
anytime (and usually will). So I don't think this will harm people too

> > Good question. What is its use? (Hint: I know how the accelerated X
> > servers work.)

> Directly accessing PCI memory I think in that case :)

Most graphics hardware can directly access all memory, so you can use it
to circumvent the MMU. This is really bad IMO.


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