Rename it to virNetDevGetIPv4AddressIoctl and make
virNetDevGetIPAddress a wrapper around it, allowing
other ways of getting the address to be implemented,
and still falling back to the old method.
Signed-off-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
This function does not make any sense now, that network driver is
(almost) dropped. I mean, previously, when threads were
serialized, this function was there to check, if no other network
with the same name or UUID exists. However, nowadays that threads
can run more in parallel, this function is useless, in fact it
gives misleading return values. Consider the following scenario.
Two threads, both trying to define networks with same name but
different UUID (e.g. because it was generated during XML parsing
phase, whatever). Lets assume that both threads are about to call
networkValidate() which immediately calls
virNetworkObjIsDuplicate().
T1: calls virNetworkObjIsDuplicate() and since no network with
given name or UUID exist, success is returned.
T2: calls virNetworkObjIsDuplicate() and since no network with
given name or UUID exist, success is returned.
T1: calls virNetworkAssignDef() and successfully places its
network into the virNetworkObjList.
T2: calls virNetworkAssignDef() and since network with the same
name exists, the network definition is replaced.
Okay, this is mainly because virNetworkAssignDef() does not check
whether name and UUID matches. Well, lets make it so! And drop
useless function too.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
There's no need to lock the network driver, as network driver
initialization is done prior accepting any client. There's nobody
to hop in and do something over partially initialized driver. Nor
qemu driver is doing that.
==30532== Observed (incorrect) order is: acquisition of lock at 0x1439EF50
==30532== at 0x4C31A26: pthread_mutex_lock (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0x5324895: virMutexLock (virthread.c:88)
==30532== by 0x5307E86: virObjectLock (virobject.c:323)
==30532== by 0x5396440: virNetworkObjListForEach (network_conf.c:4511)
==30532== by 0x19B29308: networkStateInitialize (bridge_driver.c:686)
==30532== by 0x53E1CCC: virStateInitialize (libvirt.c:777)
==30532== by 0x11DEB7: daemonRunStateInit (libvirtd.c:906)
==30532== by 0x5324B6A: virThreadHelper (virthread.c:197)
==30532== by 0x4C30456: ??? (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0xA1EC1F2: start_thread (in /lib64/libpthread-2.19.so)
==30532== by 0xA4EDC8C: clone (in /lib64/libc-2.19.so)
==30532==
==30532== followed by a later acquisition of lock at 0x1439CD60
==30532== at 0x4C31A26: pthread_mutex_lock (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0x5324895: virMutexLock (virthread.c:88)
==30532== by 0x19B27B2C: networkDriverLock (bridge_driver.c:102)
==30532== by 0x19B27B60: networkGetDnsmasqCaps (bridge_driver.c:113)
==30532== by 0x19B2856A: networkUpdateState (bridge_driver.c:389)
==30532== by 0x53963E9: virNetworkObjListForEachHelper (network_conf.c:4488)
==30532== by 0x52E2224: virHashForEach (virhash.c:521)
==30532== by 0x539645B: virNetworkObjListForEach (network_conf.c:4512)
==30532== by 0x19B29308: networkStateInitialize (bridge_driver.c:686)
==30532== by 0x53E1CCC: virStateInitialize (libvirt.c:777)
==30532== by 0x11DEB7: daemonRunStateInit (libvirtd.c:906)
==30532== by 0x5324B6A: virThreadHelper (virthread.c:197)
==30532==
==30532== Required order was established by acquisition of lock at 0x1439CD60
==30532== at 0x4C31A26: pthread_mutex_lock (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0x5324895: virMutexLock (virthread.c:88)
==30532== by 0x19B27B2C: networkDriverLock (bridge_driver.c:102)
==30532== by 0x19B28DF9: networkStateInitialize (bridge_driver.c:609)
==30532== by 0x53E1CCC: virStateInitialize (libvirt.c:777)
==30532== by 0x11DEB7: daemonRunStateInit (libvirtd.c:906)
==30532== by 0x5324B6A: virThreadHelper (virthread.c:197)
==30532== by 0x4C30456: ??? (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0xA1EC1F2: start_thread (in /lib64/libpthread-2.19.so)
==30532== by 0xA4EDC8C: clone (in /lib64/libc-2.19.so)
==30532==
==30532== followed by a later acquisition of lock at 0x1439EF50
==30532== at 0x4C31A26: pthread_mutex_lock (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0x5324895: virMutexLock (virthread.c:88)
==30532== by 0x5307E86: virObjectLock (virobject.c:323)
==30532== by 0x538A09C: virNetworkAssignDef (network_conf.c:527)
==30532== by 0x5391EB2: virNetworkLoadState (network_conf.c:3008)
==30532== by 0x53922D4: virNetworkLoadAllState (network_conf.c:3128)
==30532== by 0x19B2929A: networkStateInitialize (bridge_driver.c:671)
==30532== by 0x53E1CCC: virStateInitialize (libvirt.c:777)
==30532== by 0x11DEB7: daemonRunStateInit (libvirtd.c:906)
==30532== by 0x5324B6A: virThreadHelper (virthread.c:197)
==30532== by 0x4C30456: ??? (in /usr/lib64/valgrind/vgpreload_helgrind-amd64-linux.so)
==30532== by 0xA1EC1F2: start_thread (in /lib64/libpthread-2.19.so)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Wikipedia's list of common misspellings [1] has a machine-readable
version. This patch fixes those misspellings mentioned in the list
which don't have multiple right variants (as e.g. "accension", which can
be both "accession" and "ascension"), such misspellings are left
untouched. The list of changes was manually re-checked for false
positives.
[1] https://en.wikipedia.org/wiki/Wikipedia:Lists_of_common_misspellings/For_machines
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
The following is a long winded way to say this patch is avoiding a
false positive.
Coverity complains that calling networkPlugBandwidth() could eventually
end up with a NULL dereference on iface->bandwidth because in the
networkAllocateActualDevice there's a check of 'iface->bandwidth'
before deciding to try to use the 'portgroup' if it exists or to not
perferm the virNetDevBandwidthCopy if 'bandwidth' is not NULL.
Later in networkPlugBandwidth the 'iface->bandwidth' is sourced from
virDomainNetGetActualBandwidth - which would be either iface->bandwidth
or (preferably) iface->data.network.actual->bandwidth which would have
been filled in from either 'iface->bandwidth' or 'portgroup->bandwidth'
back in networkAllocateActualDevice
There *is* a check in networkCheckBandwidth for the result of the
virDomainNetGetActualBandwidth being NULL and a return 1 based on
that which would cause networkPlugBandwidth to exit properly and thus
never hit the condition that Coverity complains about.
However, since Coverity checks all paths - it somehow believes that
a return of 0 by networkCheckBandwidth in this condition would end
up causing the possible NULL dereference. The "fix" to silence Coverity
is to not have networkCheckBandwidth also call virDomainNetGetActualBandwidth
in order to get the ifaceBand, but rather have it accept it as an argument
which causes Coverity to "see" that it's the exit condition of 1 that won't
have the possible NULL dereference. Since we're passing that, I added the
passing of iface->mac rather than passing iface as well. This just hopefully
makes sure someone doesn't undo this in the future...
Valgrind detected a leak:
==17820== 102 (56 direct, 46 indirect) bytes in 1 blocks are definitely lost in loss record 479 of 646
==17820== at 0x4A08946: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==17820== by 0x508521A: virAllocVar (viralloc.c:560)
==17820== by 0x50D9FCA: virObjectNew (virobject.c:193)
==17820== by 0x50A4FD9: dnsmasqCapsNewEmpty (virdnsmasq.c:784)
==17820== by 0x50A514E: dnsmasqCapsNewFromBinary (virdnsmasq.c:830)
==17820== by 0x1B508287: networkStateInitialize (bridge_driver.c:666)
It looks like commit 172acef introduced the problem, because
networkGetDnsmasqCaps() increments the reference count but an
early exit never does a matching decrement.
* src/network/bridge_driver.c (networkStateCleanup): Plug leak.
Signed-off-by: Eric Blake <eblake@redhat.com>
Now that the network driver lock is ash heap of history,
we can use more of networkObjFromNetwork().
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Now that we have fine grained locks, there's no need to
lock the whole driver. We can rely on self-locking APIs.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
In order to drop network driver lock, lets annotate which
structure items are immutable, which have self-locking
APIs and so on.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This is not an immutable pointer and can change during lifetime.
Therefore, in order to drop network driver lock, we must use an
internal accessor which does not lock the network driver yet, but
it will soon. Now it merely returns an referenced object.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Well, network driver code has the driver accessible as a global
variable. This makes any rework hard, as it's unclear where the
variable is accessed and/or modified. Lets just pass the driver
as a parameter to all functions where needed.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This patch turns both virNetworkObjFindByUUID() and
virNetworkObjFindByName() to return an referenced object so that
even if caller unlocks it, it's for sure that object won't
disappear meanwhile. Especially if the object (in general) is
locked and unlocked during the caller run.
Moreover, this commit is nicely small, since the object unrefing
can be done in virNetworkObjEndAPI().
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
So far, this is pure code replacement. But once we introduce
reference counting to virNetworkObj this will be more handy as
there'll be only one function to change: virNetworkObjEndAPI().
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
So far it's just a structure which happens to have 'Obj' in its
name, but otherwise it not related to virObject at all. No
reference counting, not virObjectLock(), nothing.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Undefining a running, autostarted domain removes the autostart link, but
dom->autostart is not cleared. If the domain is subsequently redefined,
libvirt thinks it is already autostarted and will not create the link
even if requested:
# virsh dominfo example | grep Autostart
Autostart: enable
# ls /etc/libvirt/qemu/autostart/example.xml
/etc/libvirt/qemu/autostart/example.xml
# virsh undefine example
Domain example has been undefined
# virsh define example.xml
Domain example defined from example.xml
# virsh dominfo example | grep Autostart
Autostart: enable
# virsh autostart example
Domain example marked as autostarted
# ls /etc/libvirt/qemu/autostart/example.xml
ls: cannot access /etc/libvirt/qemu/autostart/example.xml: No such file or directory
This commit ensures dom->autostart is cleared whenever the config and
autostart link (if present) are removed.
The bridge network driver cleared this flag itself in networkUndefine.
This commit moves this into virNetworkDeleteConfig for symmetry with
virDomainDeleteConfig, and to ensure it is not missed in future network
drivers.
Signed-off-by: Michael Chapman <mike@very.puzzling.org>
Well, one day this will be self-locking object, but not today.
But lets prepare the code for that! Moreover,
virNetworkObjListFree() is no longer needed, so turn it into
virNetworkObjListDispose().
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
In order to hide the object internals (and use just accessors
everywhere), lets store a pointer to the object, instead of object
itself.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Instead of copying the whole object onto stack when calling the
function, just pass the pointer to the object and save up some
space on the stack. Moreover, this prepares the code to hide the
virNetworkObjList structure into network_conf.c and use accessors
only.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Moreover, there are two points within the function, where we're
missing 'goto cleanup'. Fix this too.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Okay, this is mainly for educational purposes since is called
from single point only with all the possible locks held. So
there's no way for other thread to hop in and do something wrong.
Nevertheless, we should not give bad example.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
We have this function networkObjFromNetwork() which for given
virNetworkPtr tries to find corresponding virNetworkObjPtr. If no
object is found, a nice error message is printed out:
no network with matching uuid '$uuid' ($name)
Let's improve the error message produced by networkLookupByUUID to
follow that logic.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
libvirt was unconditionally calling virNetDevBandwidthClear() for
every interface (and network bridge) of a type that supported
bandwidth, whether it actually had anything set or not. This doesn't
hurt anything (unless ifname == NULL!), but is wasteful.
This patch makes sure that all calls to virNetDevBandwidthClear() are
qualified by checking that the interface really had some bandwidth
setup done, and checks for a null ifname inside
virNetDevBandwidthClear(), silently returning success if it is null
(as well as removing the ATTRIBUTE_NONNULL from that function's
prototype, since we can't guarantee that it is never null,
e.g. sometimes a type='ethernet' interface has no ifname as it is
provided on the fly by qemu).
The function that parses the <forward> subelement of a network used to
fail/log an error if the network definition contained both a <pf>
element as well as at least one <interface> or <address> element. That
check was present because the configuration of a network should have
either one <pf>, one or more <interface>, or one or more <address>,
but never combinations of multiple kinds.
This caused a problem when libvirtd was restarted with a network
already active - when a network with a <pf> element is started, the
referenced PF (Physical Function of an SRIOV-capable network card) is
checked for VFs (Virtual Functions), and the <forward> is filled in
with a list of all VFs for that PF either in the form of their PCI
addresses (a list of <address>) or their netdev names (a list of
<interface>); the <pf> element is not removed though. When libvirtd is
restarted, it parses the network status and finds both the original
<pf> from the config, as well as the list of either <address> or
<interface>, fails the parse, and the network is not added to the
active list. This failure is often obscured because the network is
marked as autostart so libvirt immediately restarts it.
It seems odd to me that <interface> and <address> are stored in the
same array rather than keeping two separate arrays, and having
separate arrays would have made the check much simpler. However,
changing to use two separate arrays would have required changes in
more places, potentially creating more conflicts and (more
importantly) more possible regressions in the event of a backport, so
I chose to keep the existing data structure in order to localize the
change.
It appears that this problem has been in the code ever since support
for <pf> was added (0.9.10), but until commit
34cc3b2f10 (first in libvirt 1.2.4)
networks with interface pools were not properly marked as active on
restart anyway, so there is no point in backporting this patch any
further than that.
Not all files we want to find using virFileFindResource{,Full} are
generated when libvirt is built, some of them (such as RNG schemas) are
distributed with sources. The current API was not able to find source
files if libvirt was built in VPATH.
Both RNG schemas and cpu_map.xml are distributed in source tarball.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
When defining and creating networks, we have been checking to make
sure there is only a single "default" portgroup, but haven't verified
that no two portgroups have the same name. We *do* check for multiple
definitions when updating the portgroups in an existing network
though.
This patch adds a check to networkValidate(), which is called when a
network is defined or created, to disallow duplicate names. It would
actually make sense to do this in the network XML parser (since it's
not really "something that might make sense but isn't supported by
this driver", but is instead "something that should never be
allowed"), but doing that carries the danger of causing errors when
rereading the config of existing networks when libvirtd is restarted
after an upgrade, and that would result in networks disappearing from
libvirt's list. (I'm thinking I should change the error to "XML_ERROR"
instead of "UNSUPPORTED", even though that's not the type of error
that networkValidate is intended for)
This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1115858
For stateless, client side drivers, it is never correct to
probe for secondary drivers. It is only ever appropriate to
use the secondary driver that is associated with the
hypervisor in question. As a result the ESX & HyperV drivers
have both been forced to do hacks where they register no-op
drivers for the ones they don't implement.
For stateful, server side drivers, we always just want to
use the same built-in shared driver. The exception is
virtualbox which is really a stateless driver and so wants
to use its own server side secondary drivers. To deal with
this virtualbox has to be built as 3 separate loadable
modules to allow registration to work in the right order.
This can all be simplified by introducing a new struct
recording the precise set of secondary drivers each
hypervisor driver wants
struct _virConnectDriver {
virHypervisorDriverPtr hypervisorDriver;
virInterfaceDriverPtr interfaceDriver;
virNetworkDriverPtr networkDriver;
virNodeDeviceDriverPtr nodeDeviceDriver;
virNWFilterDriverPtr nwfilterDriver;
virSecretDriverPtr secretDriver;
virStorageDriverPtr storageDriver;
};
Instead of registering the hypervisor driver, we now
just register a virConnectDriver instead. This allows
us to remove all probing of secondary drivers. Once we
have chosen the primary driver, we immediately know the
correct secondary drivers to use.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This adds a new "localOnly" attribute on the domain element of the
network xml. With this set to "yes", DNS requests under that domain
will only be resolved by libvirt's dnsmasq, never forwarded upstream.
This was how it worked before commit f69a6b987d, and I found that
functionality useful. For example, I have my host's NetworkManager
dnsmasq configured to forward that domain to libvirt's dnsmasq, so I can
easily resolve guest names from outside. But if libvirt's dnsmasq
doesn't know a name and forwards it to the host, I'd get an endless
forwarding loop. Now I can set localOnly="yes" to prevent the loop.
Signed-off-by: Josh Stone <jistone@redhat.com>
Moving code for parsing and formatting network routes to
networkcommon_conf helps reusing those routes for domains. The route
definition has been hidden to help reducing the number of unnecessary
checks in the format function.
Lack of a lease (whether mac is given or not) is a normal expected
scenario, since we are already filling in rv with nleases (which is
okay as 0 if there is no lease). There is no need to raise an error.
This fixes:
> virsh # net-dhcp-leases --mac 00:50:56:c0:00:01 default
> error: Failed to get leases info for default
> error: internal error: no lease with matching MAC address: 00:50:56:c0:00:01
Signed-off-by: Nehal J Wani <nehaljw.kkd1@gmail.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
When the bridge device for a network has macTableManager='libvirt' the
intent is that all kernel management of the bridge's MAC table
(Forwarding Database, or fdb, in the case of a Linux Host Bridge) be
disabled, with libvirt handling updates to the table instead. The
setup required for the bridge itself is:
1) set the "vlan_filtering" property of the bridge device to 1.
2) If the bridge has a "Dummy" tap device used to set a fixed MAC
address on the bridge (which is always the case for a bridge created
by libvirt, and never the case for a bridge created by the host system
network config), turn off learning and unicast_flood on this tap (this
is needed even though this tap is never IFF_UP, because the kernel
ignores the IFF_UP flag of devices when using their settings to
automatically decide whether or not to turn off promiscuous mode for
any attached device).
(1) is done both for libvirt-created/managed bridges, and for bridges
that are created by the host system config, while (2) is done only for
bridges created by libvirt (i.e. for forward modes of nat, routed, and
isolated bridges)
There is no attempt to turn vlan_filtering off when destroying the
network because in the case of a libvirt-created bridge, the bridge is
about to be destroyed anyway, and in the case of a system bridge, if
the other devices attached to the bridge could operate properly before
destroying libvirt's network object, they will continue to operate
properly (this is similar to the way that libvirt will enable
ip_forwarding whenever a routed/natted network is started, but will
never attempt to disable it if they are stopped).
At the time that the network driver allocates a connection to a
network, the tap device that will be used hasn't yet been created -
that will be done later by qemu (or lxc or whoever) - but if the
network has macTableManager='libvirt', then when we do get around to
creating the tap device, we will need to add an entry for it to the
network bridge's fdb (forwarding database) *and* turn off learning and
unicast_flood for that tap device in the bridge's sysfs settings. This
means that qemu needs to know both the bridge name as well as the
setting of macTableManager, so we either need to create a new API to
retrieve that info, or just pass it back in the ActualNetDef that is
created during networkAllocateActualDevice. We choose the latter
method, since it's already done for the bridge device, and it has the
side effect of making the information available in domain status.
(NB: in the future, I think that the tap device should actually be
created by networkAllocateActualDevice(), as that will solve several
other problems, but that is a battle for another day, and this
information will still be useful outside the network driver)
When the actualType of a virDomainNetDef is "network", it means that
we are connecting to a libvirt-managed network (routed, natted, or
isolated) which does use a bridge device (created by libvirt). In the
past we have required drivers such as qemu to call the public API to
retrieve the bridge name in this case (even though it is available in
the NetDef's ActualNetDef if the actualType is "bridge" (i.e., an
externally-created bridge that isn't managed by libvirt). There is no
real reason for this difference, and as a matter of fact it
complicates things for qemu. Also, there is another bridge-related
attribute (macTableManager) that will need to be available in both
cases, so this makes things consistent.
In order to avoid problems when restarting libvirtd after an update
from an older version that *doesn't* store the network's bridgename in
the ActualNetDef, we also need to put it in place during
networkNotifyActualDevice() (this function is run for each interface
of each domain whenever libvirtd is restarted).
Along with making the bridge name available in the internal object, it
is also now reported in the <source> element of the <interface> state
XML (or the <actual> subelement in the internally-stored format).
The one oddity about this change is that usually there is a separate
union for every different "type" in a higher level object (e.g. in the
case of a virDomainNetDef there are separate "network" and "bridge"
members of the union that pivots on the type), but in this case
network and bridge types both have exactly the same attributes, so the
"bridge" member is used for both type==network and type==bridge.
https://bugzilla.redhat.com/show_bug.cgi?id=1115292
In one of the previous commits (eafb53fe) we disallowed
network-wide bandwidth to some network types. However, we
forgot about <portgroups/> which can have <bandwidth/> too.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Coverity pointed out that in other places we always check the return
value from virJSONValueObjectGetNumberLong() but not in the new addition
in leaseshelper. To solve the issue and also be more robust in case
somebody would corrupt the file, skip outputting of the lease entry in
case the expiry time is missing.
This patch enables the helper program to detect event(s) triggered when
there is a change in lease length or expiry and client-id. This
transfers complete control of leases database to libvirt and obsoletes
use of the lease database file (<network-name>.leases). That file will
not be created, read, or written. This is achieved by adding the option
--leasefile-ro to dnsmasq and passing a custom env var to leaseshelper,
which helps us map events related to leases with their corresponding
network bridges, no matter what the event be.
Also, this requires the addition of a new non-lease entry in our custom
lease database: "server-duid". It is required to identify a DHCPv6
server.
Now that dnsmasq doesn't maintain its own leases database, it relies on
our helper program to tell it about previous leases and server duid.
Thus, this patch makes our leases program honor an extra action: "init",
in which it sends the known info in a particular format to dnsmasq
by printing it to stdout.
The drawback of this change is that upgrade to this new approach does
not transfer the existing leases for the network if the leaseshelper
wasn't already used.
Starting from libvirt-1.2.4, network state XML files moved to another
directory (see commit b9e95491) and libvirt automatically migrates the
network state files to a new location. However, the code used
dirent.d_type which is not supported by all filesystems. Thus, when
libvirt was upgraded on a host which used such filesystem, network state
XMLs were not properly moved and running networks disappeared from
libvirt.
This patch falls back to lstat() whenever dirent.d_type is DT_UNKNOWN to
fix this issue.
https://bugzilla.redhat.com/show_bug.cgi?id=1167145
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
The shared network driver is stateful and inside the daemon so
there is no need to use the networkPrivateData field to get the
driver handle. Just access the global driver handle directly.
Many places already directly accessed the global driver handle
in any case, so the code could never work without relying on
this.
As is done with other items such as vlan, virtualport, and bandwidth,
set the actual trustGuestRxFilters value to be used by a domain
interface according to a merge of the same attribute in the interface,
portgroup, and network in use. the interface setting always takes
precedence (if specified), followed by portgroup, and finally the
setting in the network is used if it's not specified in the interface
or portgroup.
