Re: [Qemu-devel] [PATCH v5 0/4] -net bridge: rootless bridge support for qemu

[Corey Bryant <coreyb@linux.vnet.ibm.com>]

On 11/13/2011 10:45 PM, Corey Bryant wrote:
> With qemu it is possible to run a guest from an unprivileged user but if
> we wanted to communicate with the outside world we had to switch
> to root.
>
> We address this problem by introducing a new network backend and a new
> network option for -net tap.  This is less flexible when compared to
> existing -net tap options because it relies on a helper with elevated
> privileges to do the heavy lifting of allocating and attaching a tap
> device to a bridge.  We use a special purpose helper because we don't
> want to elevate the privileges of more generic tools like brctl.
>
> Qemu can be run with the default network helper as follows (in these cases
> attaching the tap device to the default br0 bridge):
>
>    qemu linux.img -net bridge -net nic,model=virtio
>
>    qemu linux.img -net tap,helper=/usr/local/libexec/qemu-bridge-helper
>                   -net nic,model=virtio
>
>    qemu linux.img -netdev bridge,id=hn0
>                   -device virtio-net-pci,netdev=hn0,id=nic1
>
>    qemu linux.img -netdev tap,helper=/usr/local/libexec/qemu-bridge-helper,id=hn0
>                   -device virtio-net-pci,netdev=hn0,id=nic1
>
> The default helper uses it's own ACL mechanism for access control, but
> future network helpers could be developed, for example, to support PolicyKit
> for access control.
>
> More details are included in individual patches.  The helper is broken into
> a series of patches to improve reviewabilty.
>
> v2:
>   - Updated signed-off-by's
>   - Updated author's email
>   - Set default bridge to br0
>   - Added -net bridge
>   - Updated ACL example
>   - Moved from libcap to libcap-ng
>   - Fail helper when libcap-ng not configured
>
> v3:
>   - Use simple queue to store ACLs
>   - Added goto cleanup to helper's main
>   - Allow helper execution if libcap-ng not configured
>   - Completed static analysis and memory analysis on helper
>
> v4:
>   - Update has_vnet_hdr() to return bool
>   - Update helper's main() to prevent errno clobbering
>   - Let Kernel cleanup helper's file descriptors
>
> v5:
>   - Removed if statement with TUNGETIFF ioctl() from has_vnet_hdr()
>   - Added -netdev examples and udpated qemu -help netdev documentation
>   - Disallow vnet_hdr option with -net tap,helper
>
> Corey Bryant (4):
>    Add basic version of bridge helper
>    Add access control support to qemu bridge helper
>    Add cap reduction support to enable use as SUID
>    Add support for net bridge
>
>   Makefile             |   12 ++-
>   configure            |   37 +++++
>   net.c                |   29 ++++-
>   net.h                |    3 +
>   net/tap.c            |  191 +++++++++++++++++++++++-
>   net/tap.h            |    3 +
>   qemu-bridge-helper.c |  402 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   qemu-options.hx      |   74 ++++++++--
>   8 files changed, 728 insertions(+), 23 deletions(-)
>   create mode 100644 qemu-bridge-helper.c
>

Does anyone have any comments on this patch series?  I haven't received 
any thus far for this version.  Surely no news can't be good news. :)

-- 
Regards,
Corey