7cd0911e1a
If managed='no', then the tap device must already exist, and setting of MAC address and online status (IFF_UP) is skipped. NB: we still set IFF_VNET_HDR and IFF_MULTI_QUEUE as appropriate, because those bits must be properly set in the TUNSETIFF we use to set the tap device name of the handle we've opened - if IFF_VNET_HDR has not been set and we set it the request will be honored even when running libvirtd unprivileged; if IFF_MULTI_QUEUE is requested to be different than how it was created, that will result in an error from the kernel. This means that you don't need to pay attention to IFF_VNET_HDR when creating the tap devices, but you *do* need to set IFF_MULTI_QUEUE if you're going to use multiple queues for your tap device. NB2: /dev/vhost-net normally has permissions 600, so it can't be opened by an unprivileged process. This would normally cause a warning message when using a virtio net device from an unprivileged libvirtd. I've found that setting the permissions for /dev/vhost-net permits unprivileged libvirtd to use vhost-net for virtio devices, but have no idea what sort of security implications that has. I haven't changed libvrit's code to avoid *attempting* to open /dev/vhost-net - if you are concerned about the security of opening up permissions of /dev/vhost-net (probably a good idea at least until we ask someone who knows about the code) then add <driver name='qemu'/> to the interface definition and you'll avoid the warning message. Note that virNetDevTapCreate() is the correct function to call in the case of an existing device, because the same ioctl() that creates a new tap device will also open an existing tap device. Resolves: https://bugzilla.redhat.com/1723367 (partially) Signed-off-by: Laine Stump <laine@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files COPYING.LESSER
and COPYING for full license terms & conditions.
Installation
Libvirt uses the GNU Autotools build system, so in general can be built and installed with the usual commands. For example, to build in a manner that is suitable for installing as root, use:
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
$ make
$ sudo make install
While to build & install as an unprivileged user
$ ./configure --prefix=$HOME/usr
$ make
$ make install
The libvirt code relies on a large number of 3rd party libraries. These will
be detected during execution of the configure script and a summary printed
which lists any missing (optional) dependencies.
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: