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1c9a8746ef
The exact family of the socket created for the fd used by ioctl(7) doesn't matter, it just needs to be a socket and not a file. But for some reason when macvtap support was added, it used AF_PACKET/SOCK_DGRAM sockets for its ioctls; we later used the same AF_PACKET/SOCK_DGRAM socket for new ioctls we added, and eventually modified the other pre-existing ioctl sockets (for creating/deleting bridges) to also use AF_PACKET/SOCK_DGRAM (that code originally used AF_UNIX/SOCK_STREAM). The problem with using AF_PACKET (intended for sending/receiving "raw" packets, i.e. packets that can be some protocol other than TCP or UDP) is that it requires root privileges. This meant that none of the ioctls in virnetdev.c or virnetdevip.c would work when running libvirtd unprivileged. This packet solves that problem by changing the family to AF_UNIX when creating the socket used for any ioctl().
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>