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Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd |
Date: |
Tue, 3 Jul 2012 10:07:37 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Jul 02, 2012 at 04:31:09PM -0600, Eric Blake wrote:
> On 07/02/2012 04:02 PM, Corey Bryant wrote:
>
> > Here's another option that Kevin and I discussed today on IRC. I've
> > modified a few minor details since the discussion. And Kevin please
> > correct me if anything is wrong.
> >
> > Proposal Four: Pass a set of fds via 'pass-fds'. The group of fds
> > should all refer to the same file, but may have different access flags
> > (ie. O_RDWR, O_RDONLY). qemu_open can then dup the fd that has the
> > matching access mode flags.
>
> But this means that libvirt has to open a file O_RDWR up front for any
> file that it _might_ need qemu to reopen later, and that qemu is now
> hanging on to 2 fds per fdset instead of 1 fd for the life of any client
> of the fdset.
>
> I see no reason why libvirt can't pass in an O_RDWR fd when qemu only
> needs to use an O_RDONLY fd;
If libvirt has only granted read-only access to the file with sVirt, then
passing a O_RDWR file handle to QEMU will result in an SELinux denial,
even if QEMU doesn't try to do I/O on it. So this is out of the question.
Regards,
Daniel
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- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Corey Bryant, 2012/07/02
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Eric Blake, 2012/07/02
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Corey Bryant, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Kevin Wolf, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Corey Bryant, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Eric Blake, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Corey Bryant, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Eric Blake, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Corey Bryant, 2012/07/03
- Re: [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd, Kevin Wolf, 2012/07/04