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Date:      Fri, 1 Dec 2000 17:44:08 -0700
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        hackers@FreeBSD.ORG
Cc:        stable@FreeBSD.ORG
Subject:   Re: PCIOCGETCONF/PCIOCREAD requires write permission?
Message-ID:  <20001201174408.A17122@panzer.kdm.org>
In-Reply-To: <200012012056.eB1KuDI32343@orthanc.ab.ca>; from lyndon@orthanc.ab.ca on Fri, Dec 01, 2000 at 01:56:13PM -0700
References:  <200012012056.eB1KuDI32343@orthanc.ab.ca>

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On Fri, Dec 01, 2000 at 13:56:13 -0700, Lyndon Nerenberg wrote:
> [Observed on 4.2-STABLE, but I've redirected replies to the hackers list.]
> 
> 'pciconf -l' is documented to work for non-priv users, however the
> first thing the underlying ioctl code (pci_ioctl) does is bail with EPERM
> if the caller does not have /dev/pci open for write.

The documentation is wrong, unfortunately.

> Is there any reason why the FWRITE test cannot/should not be moved down
> into the 'case PCIOCWRITE' part of the switch? This would make both
> PCIOCGETCONF and PCIOCREAD work for readonly access to /dev/pci (which
> seems to me to be saner behaviour).

At least with the PCIOCGETCONF, you need write permission, because
it copies in patterns to match against.

As for PCIOCREAD, it only allows reading of PCI registers, so the question
there is whether there are any potential security implications to allowing
non-root users to read PCI registers.  If reading configuration registers
caused performance degredation, for instance.

Ken
-- 
Kenneth Merry
ken@kdm.org


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