[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] [RFC 0/5] block: File descriptor passing using -open-hook-fd



On Tue, May 1, 2012 at 11:31 PM, Stefan Hajnoczi
<stefanha linux vnet ibm com> wrote:
> Libvirt can take advantage of SELinux to restrict the QEMU process and prevent
> it from opening files that it should not have access to.  This improves
> security because it prevents the attacker from escaping the QEMU process if
> they manage to gain control.
>
> NFS has been a pain point for SELinux because it does not support labels (which
> I believe are stored in extended attributes).  In other words, it's not
> possible to use SELinux goodness on QEMU when image files are located on NFS.
> Today we have to allow QEMU access to any file on the NFS export rather than
> restricting specifically to the image files that the guest requires.
>
> File descriptor passing is a solution to this problem and might also come in
> handy elsewhere.  Libvirt or another external process chooses files which QEMU
> is allowed to access and provides just those file descriptors - QEMU cannot
> open the files itself.
>
> This series adds the -open-hook-fd command-line option.  Whenever QEMU needs to
> open an image file it sends a request over the given UNIX domain socket.  The
> response includes the file descriptor or an errno on failure.  Please see the
> patches for details on the protocol.
>
> The -open-hook-fd approach allows QEMU to support file descriptor passing
> without changing -drive.  It also supports snapshot_blkdev and other commands
By the way, How will it support them?
> that re-open image files.
>
> Anthony Liguori <aliguori us ibm com> wrote most of these patches.  I added a
> demo -open-hook-fd server and added some small fixes.  Since Anthony is
> traveling right now I'm sending the RFC for discussion.
>
> Anthony Liguori (3):
>  block: add open() wrapper that can be hooked by libvirt
>  block: add new command line parameter that and protocol description
>  block: plumb up open-hook-fd option
>
> Stefan Hajnoczi (2):
>  osdep: add qemu_recvmsg() wrapper
>  Example -open-hook-fd server
>
>  block.c           |  107 ++++++++++++++++++++++++++++++++++++++
>  block.h           |    2 +
>  block/raw-posix.c |   18 +++----
>  block/raw-win32.c |    2 +-
>  block/vdi.c       |    2 +-
>  block/vmdk.c      |    6 +--
>  block/vpc.c       |    2 +-
>  block/vvfat.c     |    4 +-
>  block_int.h       |   12 +++++
>  osdep.c           |   46 +++++++++++++++++
>  qemu-common.h     |    2 +
>  qemu-options.hx   |   42 +++++++++++++++
>  test-fd-passing.c |  147 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  vl.c              |    3 ++
>  14 files changed, 378 insertions(+), 17 deletions(-)
>  create mode 100644 test-fd-passing.c
>
> --
> 1.7.10
>
> --
> libvir-list mailing list
> libvir-list redhat com
> https://www.redhat.com/mailman/listinfo/libvir-list



-- 
Regards,

Zhi Yong Wu


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]