[Qemu-devel] [PATCH v2 0/4] -net bridge: rootless bridge support for qemu

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

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 -hda linux.img -net bridge -net nic
or:
     qemu -hda linux.img -net tap,helper=/usr/local/libexec/qemu-bridge-helper -net nic

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

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            |  190 ++++++++++++++++++++++++-
 net/tap.h            |    2 +
 qemu-bridge-helper.c |  380 ++++++++++++++++++++++++++++++++++++++++++++++++++
 qemu-options.hx      |   73 ++++++++--
 8 files changed, 703 insertions(+), 23 deletions(-)
 create mode 100644 qemu-bridge-helper.c

-- 
1.7.3.4