Re: 2.2.0p7: fix to ioperm() ranges also needed

H. Peter Anvin (hpa@transmeta.com)
12 Jan 1999 19:53:22 GMT

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Maybe in reply to: Chris Evans: "2.2.0p7: fix to ioperm() ranges also needed"

Followup to: <Pine.LNX.3.96.990111221729.13448A-100000@ferret.lmh.ox.ac.uk>
By author: Chris Evans <chris@ferret.lmh.ox.ac.uk>
In newsgroup: linux.dev.kernel
>
> Hi,
>
> The pre-patch for 2.2.0p7 includes a fix I suggest so that an iopl(3)
> process can drop privs to iopl(0) without needing to be root to do so!
>
> As a complementary fix, processes should probably always be allowed to use
> ioperm() if they specify 0 as the "set" argument.
>
> Cheers
> Chris
>
> P.S. Offtopic. Can someome clarify for me the differences between iopl(1),
> iopl(2) and iopl(3)? Thank you!
>

On Linux/i386, only iopl(3) matters. A process is I/O privileged if
IOPL >= CPL. A Linux user-space process has CPL 3.

-hpa

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Maybe in reply to: Chris Evans: "2.2.0p7: fix to ioperm() ranges also needed"