linux-kernel - Re: [PATCH 2/2] pci: allow sysfs file owner to read device dependent config space

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Message-ID: <20100514190923.GE2505@kroah.com>
Date:	Fri, 14 May 2010 12:09:23 -0700
From:	Greg KH <greg@...ah.com>
To:	Chris Wright <chrisw@...s-sol.org>, jbarnes@...tuousgeek.org
Cc:	matthew@....cx, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	ddutile@...hat.com, alex.williamson@...hat.com
Subject: Re: [PATCH 2/2] pci: allow sysfs file owner to read device
 dependent config space

On Wed, May 12, 2010 at 06:29:57PM -0700, Chris Wright wrote:
> The PCI config space bin_attr read handler has a hardcoded CAP_SYS_ADMIN
> check to verify privileges before allowing a user to read device
> dependent config space.  This is meant to protect from an unprivileged
> user potentially locking up the box.
> 
> When assigning a PCI device directly to a guest with libvirt and KVM,
> the sysfs config space file is chown'd to the unprivileged user that
> the KVM guest will run as.  The guest needs to have full access to the
> device's config space since it's responsible for driving the device.
> However, despite being the owner of the sysfs file, the CAP_SYS_ADMIN
> check will not allow read access beyond the config header.
> 
> With this patch the sysfs file owner is also considered privileged enough
> to read all of the config space.
> 
> Signed-off-by: Chris Wright <chrisw@...s-sol.org>
> ---
>  drivers/pci/pci-sysfs.c |    4 +++-

Jesse, any objection to this going through my tree as it will depend on
the sysfs change?

thanks,

greg k-h
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