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Daniel P. Berrangé 3fff8c91b0 network: introduce a "none" firewall backend type
There are two scenarios identified after the recent firewall backend
selection was introduced, which result in libvirtd failing to startup
due to an inability to find either iptables/nftables

 - On Linux if running unprivileged with $PATH lacking the dir
   containing iptables/nftables
 - On non-Linux where iptables/nftables never existed

In the former case, it is preferrable to restore the behaviour whereby
the driver starts successfully. Users will get an error reported when
attempting to start any virtual network, due to the lack of permissions
needed to create bridge devices. This makes the missing firewall backend
irrelevant.

In the latter case, the network driver calls the 'nop' platform
implementation which does not attempt to implement any firewall logic,
just allowing the network to start without firewall rules.

To solve this are number of changes are required

 * Introduce VIR_FIREWALL_BACKEND_NONE, which does nothing except
   report a fatal error from virFirewallApply(). This code path
   is unreachable, since we'll never create a virFirewall
   object with with VIR_FIREWALL_BACKEND_NONE, so the error reporting
   is just a sanity check.

 * Ignore the compile time backend defaults and assume use of
   the 'none' backend if running unprivileged.

   This fixes the first regression, avoiding the failure to start
   libvirtd on Linux in unprivileged context, instead allowing use
   of the driver and expecting a permission denied when creating a
   bridge.

 * Reject the use of compile time backend defaults no non-Linux
   and hardcode the 'none' backend. The non-Linux platforms have
   no firewall implementation at all currently, so there's no
   reason to permit the use of 'firewall_backend_priority'
   meson option.

   This fixes the second regression, avoiding the failure to start
   libvirtd on non-Linux hosts due to non-existant Linux binaries.

 * Change the Linux platform backend to raise an error if the
   firewall backend is 'none'. Again this code path is unreachable
   by default since we'll fail to create the bridge before getting
   here, but if someone modified network.conf to request the 'none'
   backend, this will stop further progress.

 * Change the nop platform backend to raise an error if the
   firewall backend is 'iptables' or 'nftables'. Again this code
   path is unreachable, since we should already have failed to
   find the iptables/nftables binaries on non-Linux hosts, so
   this is just a sanity check.

 * 'none' is not permited as a value in 'firewall_backend_priority'
   meson option, since it is conceptually meaningless to ask for
   that on Linux.

NB, 'firewall_backend_priority' allows repeated options temporarily,
which we don't want. Meson intends to turn this into a hard error

  DEPRECATION: Duplicated values in array option is deprecated. This will become a hard error in the future.

and we can live with the reduced error checking until that happens.

Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2024-06-17 15:55:14 +01:00
.ctags.d maint: Add support for .ctags.d 2019-05-31 17:54:28 +02:00
.github/workflows github: Update lockdown message when opening a PR 2024-05-15 12:31:23 +02:00
.gitlab/issue_templates gitlab: issue_template: Remove labelling commands 2022-06-01 12:27:10 +02:00
build-aux virshtest: Prepare for testing against output files 2024-04-02 14:24:30 +02:00
ci ci: Introduce Ubuntu 24.04 2024-05-14 15:17:23 +02:00
docs docs: add libosinfo & virt-viewer to CI dashboard 2024-06-17 13:31:31 +01:00
examples examples: Define _GNU_SOURCE for more examples 2024-02-07 18:01:03 +01:00
include libvirt: Introduce virDomainGraphicsReload API 2024-03-08 17:00:15 +01:00
po network: introduce a "none" firewall backend type 2024-06-17 15:55:14 +01:00
scripts scripts/rpcgen: skip tests if tirpc is not present 2024-05-08 15:57:13 +01:00
src network: introduce a "none" firewall backend type 2024-06-17 15:55:14 +01:00
subprojects Move src/keycodemapdb -> subprojects/keycodemapdb 2023-04-17 15:02:38 +02:00
tests qemucapabilitiestest: Update test data for qemu 9.1 dev cycle 2024-06-12 08:21:12 +02:00
tools meson: fix missing use of unitdir for systemd directory 2024-06-13 10:23:07 +01:00
.ctags ctags: Generate tags for headers, i.e. function prototypes 2018-09-18 14:21:33 +02:00
.dir-locals.el build: avoid tabs that failed syntax-check 2012-09-06 09:43:46 -06:00
.editorconfig Add .editorconfig 2019-09-06 12:47:46 +02:00
.gitattributes Add .gitattributes file 2022-03-17 14:33:12 +01:00
.gitignore Revert ".gitignore: Ignore cscope and other *tags files" 2023-02-08 17:24:31 +01:00
.gitlab_pages_redirects docs: gitlab redirects: Drop '/libvirt' prefix for hosting the web through gitlab pages 2024-02-13 16:56:49 +01:00
.gitlab-ci.yml gitlab: add missing job inheritance for codestyle 2024-06-17 11:36:00 +01:00
.gitmodules Move src/keycodemapdb -> subprojects/keycodemapdb 2023-04-17 15:02:38 +02:00
.gitpublish gitpublish: Tweak prefix 2023-12-05 11:48:28 +01:00
.mailmap mailmap: consolidate my email addresses 2020-10-06 12:05:09 +02:00
AUTHORS.rst.in AUTHORS: change my (Nikolay Shirokovskiy) email 2022-04-06 11:00:53 +03:00
config.h configure: bump min required CLang to 6.0 / XCode 10.0 2022-01-17 10:44:29 +00:00
configmake.h.in meson: generate configmake.h 2020-08-03 09:26:48 +02:00
CONTRIBUTING.rst meson: adjust our documentation to mention meson instead of autoconf 2020-08-03 09:27:09 +02:00
COPYING maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
COPYING.LESSER maint: Remove control characters from LGPL license file 2015-09-25 09:16:24 +02:00
gitdm.config gitdm: add 'ibm' file 2019-10-18 17:32:52 +02:00
libvirt-admin.pc.in Add libvirt-admin library 2015-06-16 13:46:20 +02:00
libvirt-lxc.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt-qemu.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt.spec.in meson: allow systemd sysusersdir to be changed 2024-06-13 10:23:11 +01:00
meson_options.txt network: introduce a "none" firewall backend type 2024-06-17 15:55:14 +01:00
meson.build network: introduce a "none" firewall backend type 2024-06-17 15:55:14 +01:00
NEWS.rst news: document new virt-host-validate impl 2024-06-13 10:23:23 +01:00
README.rst docs: update docs pointing to old mailing list addrs 2023-10-31 10:04:27 +00:00
run.in run.in: Detect binaries in builddir properly 2024-06-04 14:39:00 +02:00

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==============================
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:

https://libvirt.org


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
============

Instructions on building and installing libvirt can be found on the website:

https://libvirt.org/compiling.html

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:

* users@lists.libvirt.org (**for user discussions**)
* devel@lists.libvirt.org (**for development only**)

Further details on contacting the project are available on the website:

https://libvirt.org/contact.html