Re: [libvirt] [PATCH v2 0/2] qemu: invoke qemu-bridge-helper from libvirtd

The <interface type='bridge'> is working mostly because of a peculiar design decision in Linux. Ideally, QEMU would run with an empty capability bounding set and would not be able to do any privileged operation (not even by running a helper program). This is not the case because dropping capabilities from the bounding set requires a capability of its own, CAP_SETPCAP; thus QEMU does *not* run with an empty bounding set if invoked via qemu:///session. This is apparently for security reasons, to avoid that dropping _some_ caps but not all of them lets you exploit untested error paths in suid binaries. This series lets libvirtd invoke the privileged helper program on its own, which is a cleaner design that would work even if the above Linux quirk was not there. Also, this adds a <target dev='tap0'/> element to the XML of an active domain using <interface type='bridge'>. Thanks to the patches that have already been committed, the recvfd and virCommand APIs make the task almost trivial. v1->v2: OOM fix in patch 1, change label name in patch 2, rebase Paolo Bonzini (2): virnetdevtap: add virNetDevTapGetName qemu: launch bridge helper from libvirtd src/libvirt_private.syms | 1 + src/qemu/qemu_command.c | 133 ++++++++++++++++++++++++++++++++++------------- src/qemu/qemu_command.h | 1 - src/qemu/qemu_hotplug.c | 25 +++------ src/util/virnetdevtap.c | 33 ++++++++++++ src/util/virnetdevtap.h | 3 ++ 6 files changed, 143 insertions(+), 53 deletions(-)