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Thomas Haller d35d3c468a settings: rework tracking settings connections and settings plugins
Completely rework how settings plugin handle connections and how
NMSettings tracks the list of connections.

Previously, settings plugins would return objects of (a subtype of) type
NMSettingsConnection. The NMSettingsConnection was tightly coupled with
the settings plugin. That has a lot of downsides.

Change that. When changing this basic relation how settings connections
are tracked, everything falls appart. That's why this is a huge change.
Also, since I have to largely rewrite the settings plugins, I also
added support for multiple keyfile directories, handle in-memory
connections only by keyfile plugin and (partly) use copy-on-write NMConnection
instances. I don't want to spend effort rewriting large parts while
preserving the old way, that anyway should change. E.g. while rewriting ifcfg-rh,
I don't want to let it handle in-memory connections because that's not right
long-term.

--

If the settings plugins themself create subtypes of NMSettingsConnection
instances, then a lot of knowledge about tracking connections moves
to the plugins.
Just try to follow the code what happend during nm_settings_add_connection().
Note how the logic is spread out:
 - nm_settings_add_connection() calls plugin's add_connection()
 - add_connection() creates a NMSettingsConnection subtype
 - the plugin has to know that it's called during add-connection and
   not emit NM_SETTINGS_PLUGIN_CONNECTION_ADDED signal
 - NMSettings calls claim_connection() which hocks up the new
   NMSettingsConnection instance and configures the instance
   (like calling nm_settings_connection_added()).
This summary does not sound like a lot, but try to follow that code. The logic
is all over the place.

Instead, settings plugins should have a very simple API for adding, modifying,
deleting, loading and reloading connections. All the plugin does is to return a
NMSettingsStorage handle. The storage instance is a handle to identify a profile
in storage (e.g. a particular file). The settings plugin is free to subtype
NMSettingsStorage, but it's not necessary.
There are no more events raised, and the settings plugin implements the small
API in a straightforward manner.
NMSettings now drives all of this. Even NMSettingsConnection has now
very little concern about how it's tracked and delegates only to NMSettings.

This should make settings plugins simpler. Currently settings plugins
are so cumbersome to implement, that we avoid having them. It should not be
like that and it should be easy, beneficial and lightweight to create a new
settings plugin.

Note also how the settings plugins no longer care about duplicate UUIDs.
Duplicated UUIDs are a fact of life and NMSettings must handle them. No
need to overly concern settings plugins with that.

--

NMSettingsConnection is exposed directly on D-Bus (being a subtype of
NMDBusObject) but it was also a GObject type provided by the settings
plugin. Hence, it was not possible to migrate a profile from one plugin to
another.
However that would be useful when one profile does not support a
connection type (like ifcfg-rh not supporting VPN). Currently such
migration is not implemented except for migrating them to/from keyfile's
run directory. The problem is that migrating profiles in general is
complicated but in some cases it is important to do.

For example checkpoint rollback should recreate the profile in the right
settings plugin, not just add it to persistent storage. This is not yet
properly implemented.

--

Previously, both keyfile and ifcfg-rh plugin implemented in-memory (unsaved)
profiles, while ifupdown plugin cannot handle them. That meant duplication of code
and a ifupdown profile could not be modified or made unsaved.
This is now unified and only keyfile plugin handles in-memory profiles (bgo #744711).
Also, NMSettings is aware of such profiles and treats them specially.
In particular, NMSettings drives the migration between persistent and non-persistent
storage.

Note that a settings plugins may create truly generated, in-memory profiles.
The settings plugin is free to generate and persist the profiles in any way it
wishes. But the concept of "unsaved" profiles is now something explicitly handled
by keyfile plugin. Also, these "unsaved" keyfile profiles are persisted to file system
too, to the /run directory. This is great for two reasons: first of all, all
profiles from keyfile storage in fact have a backing file -- even the
unsaved ones. It also means you can create "unsaved" profiles in /run
and load them with `nmcli connection load`, meaning there is a file
based API for creating unsaved profiles.
The other advantage is that these profiles now survive restarting
NetworkManager. It's paramount that restarting the daemon is as
non-disruptive as possible. Persisting unsaved files to /run improves
here significantly.

--

In the past, NMSettingsConnection also implemented NMConnection interface.
That was already changed a while ago and instead users call now
nm_settings_connection_get_connection() to delegate to a
NMSimpleConnection. What however still happened was that the NMConnection
instance gets never swapped but instead the instance was modified with
nm_connection_replace_settings_from_connection(), clear-secrets, etc.
Change that and treat the NMConnection instance immutable. Instead of modifying
it, reference/clone a new instance. This changes that previously when somebody
wanted to keep a reference to an NMConnection, then the profile would be cloned.
Now, it is supposed to be safe to reference the instance directly and everybody
must ensure not to modify the instance. nmtst_connection_assert_unchanging()
should help with that.
The point is that the settings plugins may keep references to the
NMConnection instance, and so does the NMSettingsConnection. We want
to avoid cloning the instances as long as they are the same.
Likewise, the device's applied connection can now also be referenced
instead of cloning it. This is not yet done, and possibly there are
further improvements possible.

--

Also implement multiple keyfile directores /usr/lib, /etc, /run (rh #1674545,
bgo #772414).

It was always the case that multiple files could provide the same UUID
(both in case of keyfile and ifcfg-rh). For keyfile plugin, if a profile in
read-only storage in /usr/lib gets modified, then it gets actually stored in
/etc (or /run, if the profile is unsaved).

--

While at it, make /etc/network/interfaces profiles for ifupdown plugin reloadable.

--

https://bugzilla.gnome.org/show_bug.cgi?id=772414
https://bugzilla.gnome.org/show_bug.cgi?id=744711
https://bugzilla.redhat.com/show_bug.cgi?id=1674545
2019-07-16 19:09:08 +02:00
clients clients/metta-setting-desc: allow "system" and "dpdk" ovs interface types 2019-07-10 15:04:29 +02:00
contrib settings: rework tracking settings connections and settings plugins 2019-07-16 19:09:08 +02:00
data settings: drop ibft settings plugin 2019-06-20 16:06:44 +02:00
dispatcher dispatcher: add MS Azure endpoint env var expected by cloud-init 2019-07-05 15:17:04 +02:00
docs libnm-core: add ovs-dpdk setting 2019-06-14 12:10:20 +02:00
examples all: drop vim file variables from source files 2019-06-11 10:08:07 +02:00
introspection settings: rework tracking settings connections and settings plugins 2019-07-16 19:09:08 +02:00
libnm libnm,core: add support for "suppress_prefixlength" rule attribute 2019-07-16 10:03:17 +02:00
libnm-core settings: rework tracking settings connections and settings plugins 2019-07-16 19:09:08 +02:00
m4 all: drop emacs file variables from source files 2019-06-11 10:04:00 +02:00
man man: update nm-openswitch example 2019-07-09 12:05:32 +02:00
po po: update Brazilian Portuguese (pt_BR) translation 2019-07-15 09:55:09 +02:00
shared shared: suppress -Werror=stringop-overflow= warning in nm_strndup_a() 2019-07-16 10:48:38 +02:00
src settings: rework tracking settings connections and settings plugins 2019-07-16 19:09:08 +02:00
tools settings: rework tracking settings connections and settings plugins 2019-07-16 19:09:08 +02:00
vapi all: goodbye libnm-glib 2019-04-16 15:52:27 +02:00
.dir-locals.el misc: add toplevel .dir-locals file that tells Emacs to show trailing whitespace 2013-03-08 15:15:28 +01:00
.gitignore settings: drop ibft settings plugin 2019-06-20 16:06:44 +02:00
.gitlab-ci.yml gitlab-ci: workaround build failure in Debian:sid due to iproute2 issue 2019-07-12 10:45:36 +02:00
.mailmap mailmap: update user 2018-10-01 12:02:55 +02:00
.travis.yml all: goodbye libnm-glib 2019-04-16 15:52:27 +02:00
AUTHORS misc: update maintainers and authors 2016-04-21 13:39:03 -05:00
autogen.sh all: goodbye libnm-glib 2019-04-16 15:52:27 +02:00
ChangeLog all: point git references to the GitLab instance 2018-08-27 11:36:56 +02:00
config-extra.h.meson build: remove duplicate and unused RUNDIR define 2019-05-17 21:24:18 +02:00
config-extra.h.mk build/autotools: generate "config-extra.h" via makefile "config-extra.h.mk" 2019-06-17 17:42:09 +02:00
config.h.meson systemd: merge branch systemd into master 2019-07-05 09:13:53 +02:00
configure.ac systemd: merge branch systemd into master 2019-07-05 09:13:53 +02:00
CONTRIBUTING CONTRIBUTING: update section about assertions in NetworkManager 2019-06-26 09:53:54 +02:00
COPYING docs: create new master NM documentation module 2011-02-16 16:24:16 -06:00
linker-script-binary.ver iface-helper/build: add linker version script 2016-10-13 21:33:33 +02:00
linker-script-devices.ver devices/build: use one linker-script-devices.ver for all device plugins 2016-10-13 21:36:06 +02:00
linker-script-settings.ver settings/build: add linker version script for settings plugins 2016-10-13 21:33:33 +02:00
MAINTAINERS misc: update maintainers and authors 2016-04-21 13:39:03 -05:00
Makefile.am settings: rework tracking settings connections and settings plugins 2019-07-16 19:09:08 +02:00
Makefile.examples examples: add python example script "nm-wg-set" for modifying WireGuard profile 2019-02-22 11:00:11 +01:00
Makefile.glib all: drop emacs file variables from source files 2019-06-11 10:04:00 +02:00
Makefile.vapigen build: fix make always re-making vapigen target 2016-10-21 18:46:03 +02:00
meson.build systemd: merge branch systemd into master 2019-07-05 09:13:53 +02:00
meson_options.txt dhcp: add nettools dhcp4 client 2019-07-05 11:04:32 +02:00
NetworkManager.pc.in build: update NetworkManager.pc 2013-01-29 16:17:30 -05:00
NEWS settings: drop ibft settings plugin 2019-06-20 16:06:44 +02:00
README all: drop empty first line from sources 2019-06-11 10:15:06 +02:00
TODO all: say Wi-Fi instead of "wifi" or "WiFi" 2018-11-29 17:53:35 +01:00
valgrind.suppressions all: goodbye libnm-glib 2019-04-16 15:52:27 +02:00
zanata.xml po: add Zanata configuration 2016-04-05 14:35:53 +02:00

******************
NetworkManager core daemon has moved to gitlab.freedesktop.org!

git clone https://gitlab.freedesktop.org/NetworkManager/NetworkManager.git
******************


Networking that Just Works
--------------------------

NetworkManager attempts to keep an active network connection available at all
times.  The point of NetworkManager is to make networking configuration and
setup as painless and automatic as possible.  NetworkManager is intended to
replace default route, replace other routes, set IP addresses, and in general
configure networking as NM sees fit (with the possibility of manual override as
necessary).  In effect, the goal of NetworkManager is to make networking Just
Work with a minimum of user hassle, but still allow customization and a high
level of manual network control.  If you have special needs, we'd like to hear
about them, but understand that NetworkManager is not intended for every
use-case.

NetworkManager will attempt to keep every network device in the system up and
active, as long as the device is available for use (has a cable plugged in,
the killswitch isn't turned on, etc).  Network connections can be set to
'autoconnect', meaning that NetworkManager will make that connection active
whenever it and the hardware is available.

"Settings services" store lists of user- or administrator-defined "connections",
which contain all the settings and parameters required to connect to a specific
network.  NetworkManager will _never_ activate a connection that is not in this
list, or that the user has not directed NetworkManager to connect to.


How it works:

The NetworkManager daemon runs as a privileged service (since it must access
and control hardware), but provides a D-Bus interface on the system bus to
allow for fine-grained control of networking.  NetworkManager does not store
connections or settings, it is only the mechanism by which those connections
are selected and activated.

To store pre-defined network connections, two separate services, the "system
settings service" and the "user settings service" store connection information
and provide these to NetworkManager, also via D-Bus.  Each settings service
can determine how and where it persistently stores the connection information;
for example, the GNOME applet stores its configuration in GConf, and the system
settings service stores its config in distro-specific formats, or in a distro-
agnostic format, depending on user/administrator preference.

A variety of other system services are used by NetworkManager to provide
network functionality: wpa_supplicant for wireless connections and 802.1x
wired connections, pppd for PPP and mobile broadband connections, DHCP clients
for dynamic IP addressing, dnsmasq for proxy nameserver and DHCP server
functionality for internet connection sharing, and avahi-autoipd for IPv4
link-local addresses.  Most communication with these daemons occurs, again,
via D-Bus.


Why doesn't my network Just Work?

Driver problems are the #1 cause of why NetworkManager sometimes fails to
connect to wireless networks.  Often, the driver simply doesn't behave in a
consistent manner, or is just plain buggy.  NetworkManager supports _only_
those drivers that are shipped with the upstream Linux kernel, because only
those drivers can be easily fixed and debugged.  ndiswrapper, vendor binary
drivers, or other out-of-tree drivers may or may not work well with
NetworkManager, precisely because they have not been vetted and improved by the
open-source community, and because problems in these drivers usually cannot
be fixed.

Sometimes, command-line tools like 'iwconfig' will work, but NetworkManager will
fail.  This is again often due to buggy drivers, because these drivers simply
aren't expecting the dynamic requests that NetworkManager and wpa_supplicant
make.  Driver bugs should be filed in the bug tracker of the distribution being
run, since often distributions customize their kernel and drivers.

Sometimes, it really is NetworkManager's fault.  If you think that's
the case, please file a bug at:

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues

Attaching NetworkManager debug logs from the journal (or wherever your
distribution directs syslog's 'daemon' facility output, as
/var/log/messages or /var/log/daemon.log) is often very helpful, and
(if you can get) a working wpa_supplicant config file helps
enormously.  See the logging section of file
contrib/fedora/rpm/NetworkManager.conf for how to enable debug logging
in NetworkManager.