[libvirt] [PATCH v2 2/2] selinux: add security selinux function to label tapfd

[Eric Blake]

On 10/15/2012 03:03 AM, Guannan Ren wrote:
> BZ:https://bugzilla.redhat.com/show_bug.cgi?id=851981
> When using macvtap, a character device gets first created by
> kernel with name /dev/tapN, its selinux context is:
> system_u:object_r:device_t:s0
> 
> Shortly, when udev gets notification when new file is created
> in /dev, it will then jump in and relabel this file back to the
> expected default context:
> system_u:object_r:tun_tap_device_t:s0
> 
> There is a time gap happened.
> Sometimes, it will have migration failed, AVC error message:
> type=AVC msg=audit(1349858424.233:42507): avc:  denied  { read write } for
> pid=19926 comm="qemu-kvm" path="/dev/tap33" dev=devtmpfs ino=131524
> scontext=unconfined_u:system_r:svirt_t:s0:c598,c908
> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
> 
> This patch will label the tapfd device before qemu process starts:
> system_u:object_r:tun_tap_device_t:MCS(MCS from seclabel->label)
> ---

This patch is breaking things for me - with it applied, I'm now seeing
/dev/net/tun with a label of :MCS that matches the most recently started
guest, which prevents other tun clients (like openvpn) from creating
their own tapfd.  I haven't yet looked closely to see where in this
patch you are labeling the wrong file, but it needs to be fixed.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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