Rewrite multiple hotunplug functions to to use the
virProcessRunInMountNamespace helper. This avoids
risk of a malicious guest replacing /dev with an absolute
symlink, tricking the driver into changing the host OS
filesystem.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 5fc590ad)

Conflicts:
	src/lxc/lxc_driver.c: OOM + cgroups error reporting

Rewrite lxcDomainAttachDeviceHostdevMiscLive function
to use the virProcessRunInMountNamespace helper. This avoids
risk of a malicious guest replacing /dev with a absolute
symlink, tricking the driver into changing the host OS
filesystem.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 1cadeafc)

Conflicts:
	src/lxc/lxc_driver.c: OOM + cgroups error reporting

Rewrite lxcDomainAttachDeviceHostdevStorageLive function
to use the virProcessRunInMountNamespace helper. This avoids
risk of a malicious guest replacing /dev with a absolute
symlink, tricking the driver into changing the host OS
filesystem.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 1754c7f0)

Conflicts:
	src/lxc/lxc_driver.c: OOM + cgroups error reporting

Rewrite lxcDomainAttachDeviceHostdevSubsysUSBLive function
to use the virProcessRunInMountNamespace helper. This avoids
risk of a malicious guest replacing /dev with a absolute
symlink, tricking the driver into changing the host OS
filesystem.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 7fba01c1)

Conflicts:
	src/lxc/lxc_driver.c: OOM + cgroups error reporting

Rewrite lxcDomainAttachDeviceDiskLive function to use the
virProcessRunInMountNamespace helper. This avoids risk of
a malicious guest replacing /dev with a absolute symlink,
tricking the driver into changing the host OS filesystem.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 4dd3a7d5)

Conflicts:
	src/lxc/lxc_driver.c: OOM + cgroups error reporting and
        remove usernamespace integration

Use helper virProcessRunInMountNamespace in lxcDomainShutdownFlags and
lxcDomainReboot.  Otherwise, a malicious guest could use symlinks
to force the host to manipulate the wrong file in the host's namespace.

Idea by Dan Berrange, based on an initial report by Reco
<recoverym4n@gmail.com> at
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732394Signed-off-by: NEric Blake <eblake@redhat.com>
(cherry picked from commit aebbcdd3)

Conflicts:
	src/lxc/lxc_driver.c: OOM error reporting changes
	src/util/virinitctl.c: OOM error reporting changes

Implement virProcessRunInMountNamespace, which runs callback of type
virProcessNamespaceCallback in a container namespace. This uses a
child process to run the callback, since you can't change the mount
namespace of a thread. This implies that callbacks have to be careful
about what code they run due to async safety rules.

Idea by Dan Berrange, based on an initial report by Reco
<recoverym4n@gmail.com> at
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732394Signed-off-by: NDaniel Berrange <berrange@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
(cherry picked from commit 7c72ef6f)

Backport fixed for OOM error reporting

Add a helper function which takes a file path and ensures
that all directory components leading up to the file exist.
IOW, it strips the filename part of the path and passes
the result to virFileMakePath.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit c321bfc5)

The check for whether the cgroup devices ACL is available is
done quite late during LXC hotplug - in fact after the device
node is already created in the container in some cases. Better
to do it upfront so we fail immediately.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit c3eb12ca)

The LXC disk hotplug code was allowing block or character devices
to be given as disk. A disk is always a block device.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit d24e6b8b)

When detaching a USB device from an LXC guest we must remove
the device from the cgroup ACL. Unfortunately we were telling
the cgroup code to use the guest /dev path, not the host /dev
path, and the guest device node had already been unlinked.
This was, however, fortunate since the code passed &priv->cgroup
instead of priv->cgroup, so would have crash if the device node
were accessible.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 2c2bec94)

After hotplugging a USB device, the LXC driver forgot
to add the device def to the virDomainDefPtr.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit a537827d)

Backport fixed for OOM error reporting

The LXC code missed the 'usb' component out of the path
/dev/bus/usb/$BUSNUM/$DEVNUM, so it failed to actually
setup cgroups for the device. This was in fact lucky
because the call to virLXCSetupHostUsbDeviceCgroup
was also mistakenly passing '&priv->cgroup' instead of
just 'priv->cgroup'. So once the path is fixed, libvirtd
would then crash trying to access the bogus virCgroupPtr
pointer. This would have been a security issue, were it
not for the bogus path preventing the pointer reference
being reached.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit c3648972)

virDomainDefCompatibleDevice blocks use of USB if no USB
controller is present. This is not correct for containers
since devices can be assigned directly regardless of any
controllers.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 7a44af96)

Our backing file chain code was not very robust to an ill-timed
EINTR, which could lead to a short read causing us to randomly
treat metadata differently than usual.  But the existing
virFileReadLimFD forces an error if we don't read the entire
file, even though we only care about the header of the file.
So add a new virFile function that does what we want.

* src/util/virfile.h (virFileReadHeaderFD): New prototype.
* src/util/virfile.c (virFileReadHeaderFD): New function.
* src/libvirt_private.syms (virfile.h): Export it.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileProbeFormatFromFD): Use it.
Signed-off-by: NEric Blake <eblake@redhat.com>
(cherry picked from commit 5327fad4)

Conflicts:
	src/util/virstoragefile.c: OOM error reporting & buffer signedness

* src/lxc/lxc_controller.c (virLXCControllerSetupDisk): Fix typo.
* src/lxc/lxc_driver.c (lxcDomainAttachDeviceDiskLive): Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>
(cherry picked from commit 8de47efd)

Conflicts:
	src/lxc/lxc_controller.c: No userns support yet

Free dst before lxcDomainAttachDeviceDiskLive returns
Signed-off-by: NChen Hanxiao <chenhanxiao@cn.fujitsu.com>
(cherry picked from commit c82513ac)

The variable vroot should be freed in label cleanup.

(cherry picked from commit 46c9bce4)

Signed-off-by: NEric Blake <eblake@redhat.com>
(cherry picked from commit 5b4c035b)

Create parent directroy for hostdev automatically when we
start a lxc domain or attach a hostdev to a lxc domain.
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>
(cherry picked from commit 468ee0bc)

This helper function is used to create parent directory for
the hostdev which will be added to the container. If the
parent directory of this hostdev doesn't exist, the mknod of
the hostdev will fail. eg with /dev/net/tun
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>
(cherry picked from commit c0d8c7c8)

The NWFilter code has as a deadlock race condition between
the virNWFilter{Define,Undefine} APIs and starting of guest
VMs due to mis-matched lock ordering.

In the virNWFilter{Define,Undefine} codepaths the lock ordering
is

  1. nwfilter driver lock
  2. virt driver lock
  3. nwfilter update lock
  4. domain object lock

In the VM guest startup paths the lock ordering is

  1. virt driver lock
  2. domain object lock
  3. nwfilter update lock

As can be seen the domain object and nwfilter update locks are
not acquired in a consistent order.

The fix used is to push the nwfilter update lock upto the top
level resulting in a lock ordering for virNWFilter{Define,Undefine}
of

  1. nwfilter driver lock
  2. nwfilter update lock
  3. virt driver lock
  4. domain object lock

and VM start using

  1. nwfilter update lock
  2. virt driver lock
  3. domain object lock

This has the effect of serializing VM startup once again, even if
no nwfilters are applied to the guest. There is also the possibility
of deadlock due to a call graph loop via virNWFilterInstantiate
and virNWFilterInstantiateFilterLate.

These two problems mean the lock must be turned into a read/write
lock instead of a plain mutex at the same time. The lock is used to
serialize changes to the "driver->nwfilters" hash, so the write lock
only needs to be held by the define/undefine methods. All other
methods can rely on a read lock which allows good concurrency.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 6e5c79a1)

Conflicts:
	src/conf/nwfilter_conf.c
          - virReportOOMError() in context of one hunk.
	src/lxc/lxc_driver.c
          - functions renamed, and lxc object locking changed, creating
            a conflict in the context.

Add virRWLock backed up by a POSIX rwlock primitive
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit c065984b)

The virConnectPtr is passed around loads of nwfilter code in
order to provide it as a parameter to the callback registered
by the virt drivers. None of the virt drivers use this param
though, so it serves no purpose.

Avoiding the need to pass a virConnectPtr means that the
nwfilterStateReload method no longer needs to open a bogus
QEMU driver connection. This addresses a race condition that
can lead to a crash on startup.

The nwfilter driver starts before the QEMU driver and registers
some callbacks with DBus to detect firewalld reload. If the
firewalld reload happens while the QEMU driver is still starting
up though, the nwfilterStateReload method will open a connection
to the partially initialized QEMU driver and cause a crash.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 999d72fb)

The nwfilter driver only needs a reference to its private
state object, not a full virConnectPtr. Update the domUpdateCBStruct
struct to have a 'void *opaque' field instead of a virConnectPtr.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit ebca369e)

None of the virNWFilterDefParse* methods require a virConnectPtr
arg, so just drop it
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit b77b16ce)

For inexplicable reasons, the nwfilter XML parser is intentionally
ignoring errors that arise during parsing. As well as meaning that
users don't get any feedback on their XML mistakes, this will lead
it to silently drop data in OOM conditions.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 4f209434)

Ever since ACL filtering was added in commit 76397360 (v1.1.1), a
user could still use event registration to obtain access to a
domain that they could not normally access via virDomainLookup*
or virConnectListAllDomains and friends.  We already have the
framework in the RPC generator for creating the filter, and
previous cleanup patches got us to the point that we can now
wire the filter through the entire object event stack.

Furthermore, whether or not domain:getattr is honored, use of
global events is a form of obtaining a list of networks, which
is covered by connect:search_domains added in a93cd08f (v1.1.0).
Ideally, we'd have a way to enforce connect:search_domains when
doing global registrations while omitting that check on a
per-domain registration.  But this patch just unconditionally
requires connect:search_domains, even when no list could be
obtained, based on the following observations:
1. Administrators are unlikely to grant domain:getattr for one
or all domains while still denying connect:search_domains - a
user that is able to manage domains will want to be able to
manage them efficiently, but efficient management includes being
able to list the domains they can access.  The idea of denying
connect:search_domains while still granting access to individual
domains is therefore not adding any real security, but just
serves as a layer of obscurity to annoy the end user.
2. In the current implementation, domain events are filtered
on the client; the server has no idea if a domain filter was
requested, and must therefore assume that all domain event
requests are global.  Even if we fix the RPC protocol to
allow for server-side filtering for newer client/server combos,
making the connect:serach_domains ACL check conditional on
whether the domain argument was NULL won't benefit older clients.
Therefore, we choose to document that connect:search_domains
is a pre-requisite to any domain event management.

Network events need the same treatment, with the obvious
change of using connect:search_networks and network:getattr.

* src/access/viraccessperm.h
(VIR_ACCESS_PERM_CONNECT_SEARCH_DOMAINS)
(VIR_ACCESS_PERM_CONNECT_SEARCH_NETWORKS): Document additional
effect of the permission.
* src/conf/domain_event.h (virDomainEventStateRegister)
(virDomainEventStateRegisterID): Add new parameter.
* src/conf/network_event.h (virNetworkEventStateRegisterID):
Likewise.
* src/conf/object_event_private.h (virObjectEventStateRegisterID):
Likewise.
* src/conf/object_event.c (_virObjectEventCallback): Track a filter.
(virObjectEventDispatchMatchCallback): Use filter.
(virObjectEventCallbackListAddID): Register filter.
* src/conf/domain_event.c (virDomainEventFilter): New function.
(virDomainEventStateRegister, virDomainEventStateRegisterID):
Adjust callers.
* src/conf/network_event.c (virNetworkEventFilter): New function.
(virNetworkEventStateRegisterID): Adjust caller.
* src/remote/remote_protocol.x
(REMOTE_PROC_CONNECT_DOMAIN_EVENT_REGISTER)
(REMOTE_PROC_CONNECT_DOMAIN_EVENT_REGISTER_ANY)
(REMOTE_PROC_CONNECT_NETWORK_EVENT_REGISTER_ANY): Generate a
filter, and require connect:search_domains instead of weaker
connect:read.
* src/test/test_driver.c (testConnectDomainEventRegister)
(testConnectDomainEventRegisterAny)
(testConnectNetworkEventRegisterAny): Update callers.
* src/remote/remote_driver.c (remoteConnectDomainEventRegister)
(remoteConnectDomainEventRegisterAny): Likewise.
* src/xen/xen_driver.c (xenUnifiedConnectDomainEventRegister)
(xenUnifiedConnectDomainEventRegisterAny): Likewise.
* src/vbox/vbox_tmpl.c (vboxDomainGetXMLDesc): Likewise.
* src/libxl/libxl_driver.c (libxlConnectDomainEventRegister)
(libxlConnectDomainEventRegisterAny): Likewise.
* src/qemu/qemu_driver.c (qemuConnectDomainEventRegister)
(qemuConnectDomainEventRegisterAny): Likewise.
* src/uml/uml_driver.c (umlConnectDomainEventRegister)
(umlConnectDomainEventRegisterAny): Likewise.
* src/network/bridge_driver.c
(networkConnectNetworkEventRegisterAny): Likewise.
* src/lxc/lxc_driver.c (lxcConnectDomainEventRegister)
(lxcConnectDomainEventRegisterAny): Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>
(cherry picked from commit f9f56340)

Conflicts:
	1.1.0 had a framework for generating filter methods, but
nothing actually used them.  Therefore, the only leak in this
branch was the failure to honor connect:search_domains, and that
is fixed by backporting just the patch to remote_protocol.x to
properly annotate ACL categories, and to viraccessperms.h to
document the scope of the ACL.

While running objecteventtest, it was found that valgrind pointed out the
following memory leak:

==13464== 5 bytes in 1 blocks are definitely lost in loss record 7 of 134
==13464==    at 0x4A0887C: malloc (vg_replace_malloc.c:270)
==13464==    by 0x341F485E21: strdup (strdup.c:42)
==13464==    by 0x4CAE28F: virStrdup (virstring.c:554)
==13464==    by 0x4CF3CBE: virObjectEventCallbackListAddID (object_event.c:286)
==13464==    by 0x4CF49CA: virObjectEventStateRegisterID (object_event.c:729)
==13464==    by 0x4CF73FE: virDomainEventStateRegisterID (domain_event.c:1424)
==13464==    by 0x4D7358F: testConnectDomainEventRegisterAny (test_driver.c:6032)
==13464==    by 0x4D600C8: virConnectDomainEventRegisterAny (libvirt.c:19128)
==13464==    by 0x402409: testDomainStartStopEvent (objecteventtest.c:232)
==13464==    by 0x403451: virtTestRun (testutils.c:138)
==13464==    by 0x402012: mymain (objecteventtest.c:395)
==13464==    by 0x403AF2: virtTestMain (testutils.c:593)
==13464==

(cherry picked from commit 34d52b34)

Conflicts:
	src/conf/object_event.c - 1.2.1 refactoring to object_event not
backported, so change applied directly in older domain_event.c instead

The @list->callbacks is an array that is inflated whenever a new event
is added, e.g. via virDomainEventCallbackListAddID(). However, when we
are freeing the array, we free the items within it but forgot to
actually free it.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
(cherry picked from commit ea13a759)

https://bugzilla.redhat.com/show_bug.cgi?id=1047577

When writing commit 173c2914, I missed the fact virNetServerClientClose
unlocks the client object before actually clearing client->sock and thus
it is possible to hit a window when client->keepalive is NULL while
client->sock is not NULL. I was thinking client->sock == NULL was a
better check for a closed connection but apparently we have to go with
client->keepalive == NULL to actually fix the crash.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
(cherry picked from commit 066c8ef6)

https://bugzilla.redhat.com/show_bug.cgi?id=1047577

When a client closes its connection to libvirtd early during
virConnectOpen, more specifically just after making
REMOTE_PROC_CONNECT_SUPPORTS_FEATURE call to check if
VIR_DRV_FEATURE_PROGRAM_KEEPALIVE is supported without even waiting for
the result, libvirtd may crash due to a race in keep-alive
initialization. Once receiving the REMOTE_PROC_CONNECT_SUPPORTS_FEATURE
call, the daemon's event loop delegates it to a worker thread. In case
the event loop detects EOF on the connection and calls
virNetServerClientClose before the worker thread starts to handle
REMOTE_PROC_CONNECT_SUPPORTS_FEATURE call, client->keepalive will be
disposed by the time virNetServerClientStartKeepAlive gets called from
remoteDispatchConnectSupportsFeature. Because the flow is common for
both authenticated and read-only connections, even unprivileged clients
may cause the daemon to crash.

To avoid the crash, virNetServerClientStartKeepAlive needs to check if
the connection is still open before starting keep-alive protocol.

Every libvirt release since 0.9.8 is affected by this bug.

(cherry picked from commit 173c2914)

CVE-2013-6458

Every API that is going to begin a job should do that before fetching
data from vm->def.

(cherry picked from commit 3b564259)

Every API that is going to begin a job should do that before fetching
data from vm->def.

(cherry picked from commit ff5f30b6)

CVE-2013-6458

Every API that is going to begin a job should do that before fetching
data from vm->def.

(cherry picked from commit f93d2caa)

CVE-2013-6458

Generally, every API that is going to begin a job should do that before
fetching data from vm->def. However, qemuDomainGetBlockInfo does not
know whether it will have to start a job or not before checking vm->def.
To avoid using disk alias that might have been freed while we were
waiting for a job, we use its copy. In case the disk was removed in the
meantime, we will fail with "cannot find statistics for device '...'"
error message.

(cherry picked from commit b7992595)

CVE-2013-6458
https://bugzilla.redhat.com/show_bug.cgi?id=1043069

When virDomainDetachDeviceFlags is called concurrently to
virDomainBlockStats: libvirtd may crash because qemuDomainBlockStats
finds a disk in vm->def before getting a job on a domain and uses the
disk pointer after getting the job. However, the domain in unlocked
while waiting on a job condition and thus data behind the disk pointer
may disappear. This happens when thread 1 runs
virDomainDetachDeviceFlags and enters monitor to actually remove the
disk. Then another thread starts running virDomainBlockStats, finds the
disk in vm->def, and while it's waiting on the job condition (owned by
the first thread), the first thread finishes the disk removal. When the
second thread gets the job, the memory pointed to be the disk pointer is
already gone.

That said, every API that is going to begin a job should do that before
fetching data from vm->def.

(cherry picked from commit db86da5c)

The function doesn't check whether the request is made for active or
inactive domain.  Thus when the domain is not running it still tries
accessing non-existing cgroups (priv->cgroup, which is NULL).

I re-made the function in order for it to work the same way it's qemu
counterpart does.

Reproducer:
 1) Define an LXC domain
 2) Do 'virsh memtune <domain> --hard-limit 133T'

Backtrace:
 Thread 6 (Thread 0x7fffec8c0700 (LWP 26826)):
 #0  0x00007ffff70edcc4 in virCgroupPathOfController (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", path=0x7fffec8bf718) at util/vircgroup.c:1764
 #1  0x00007ffff70e9206 in virCgroupSetValueStr (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", value=0x7fffe409f360 "1073741824")
     at util/vircgroup.c:669
 #2  0x00007ffff70e98b4 in virCgroupSetValueU64 (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", value=1073741824) at util/vircgroup.c:740
 #3  0x00007ffff70ee518 in virCgroupSetMemory (group=0x0, kb=1048576) at util/vircgroup.c:1904
 #4  0x00007ffff70ee675 in virCgroupSetMemoryHardLimit (group=0x0, kb=1048576)
     at util/vircgroup.c:1944
 #5  0x00005555557d54c8 in lxcDomainSetMemoryParameters (dom=0x7fffe40cc420,
     params=0x7fffe409f100, nparams=1, flags=0) at lxc/lxc_driver.c:774
 #6  0x00007ffff72c20f9 in virDomainSetMemoryParameters (domain=0x7fffe40cc420,
     params=0x7fffe409f100, nparams=1, flags=0) at libvirt.c:4051
 #7  0x000055555561365f in remoteDispatchDomainSetMemoryParameters (server=0x555555eb7e00,
     client=0x555555ec4b10, msg=0x555555eb94e0, rerr=0x7fffec8bfb70, args=0x7fffe40b8510)
     at remote_dispatch.h:7621
 #8  0x00005555556133fd in remoteDispatchDomainSetMemoryParametersHelper (server=0x555555eb7e00,
     client=0x555555ec4b10, msg=0x555555eb94e0, rerr=0x7fffec8bfb70, args=0x7fffe40b8510,
     ret=0x7fffe40b84f0) at remote_dispatch.h:7591
 #9  0x00007ffff73b293f in virNetServerProgramDispatchCall (prog=0x555555ec3ae0,
     server=0x555555eb7e00, client=0x555555ec4b10, msg=0x555555eb94e0)
     at rpc/virnetserverprogram.c:435
 #10 0x00007ffff73b207f in virNetServerProgramDispatch (prog=0x555555ec3ae0,
     server=0x555555eb7e00, client=0x555555ec4b10, msg=0x555555eb94e0)
     at rpc/virnetserverprogram.c:305
 #11 0x00007ffff73a4d2c in virNetServerProcessMsg (srv=0x555555eb7e00, client=0x555555ec4b10,
     prog=0x555555ec3ae0, msg=0x555555eb94e0) at rpc/virnetserver.c:165
 #12 0x00007ffff73a4e8d in virNetServerHandleJob (jobOpaque=0x555555ec3e30, opaque=0x555555eb7e00)
     at rpc/virnetserver.c:186
 #13 0x00007ffff7187f3f in virThreadPoolWorker (opaque=0x555555eb7ac0) at util/virthreadpool.c:144
 #14 0x00007ffff718733a in virThreadHelper (data=0x555555eb7890) at util/virthreadpthread.c:161
 #15 0x00007ffff468ed89 in start_thread (arg=0x7fffec8c0700) at pthread_create.c:308
 #16 0x00007ffff3da26bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>
(cherry picked from commit 9faf3f29)

Conflicts:
	src/lxc/lxc_driver.c

The function doesn't check whether the request is made for active or
inactive domain.  Thus when the domain is not running it still tries
accessing non-existing cgroups (priv->cgroup, which is NULL).

I re-made the function in order for it to work the same way it's qemu
counterpart does.

Reproducer:
 1) Define an LXC domain
 2) Do 'virsh memtune <domain>'

Backtrace:
 Thread 6 (Thread 0x7fffec8c0700 (LWP 13387)):
 #0  0x00007ffff70edcc4 in virCgroupPathOfController (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", path=0x7fffec8bf750) at util/vircgroup.c:1764
 #1  0x00007ffff70e958c in virCgroupGetValueStr (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", value=0x7fffec8bf7c0) at util/vircgroup.c:705
 #2  0x00007ffff70e9d29 in virCgroupGetValueU64 (group=0x0, controller=3,
     key=0x7ffff75734bd "memory.limit_in_bytes", value=0x7fffec8bf810) at util/vircgroup.c:804
 #3  0x00007ffff70ee706 in virCgroupGetMemoryHardLimit (group=0x0, kb=0x7fffec8bf8a8)
     at util/vircgroup.c:1962
 #4  0x00005555557d590f in lxcDomainGetMemoryParameters (dom=0x7fffd40024a0,
     params=0x7fffd40027a0, nparams=0x7fffec8bfa24, flags=0) at lxc/lxc_driver.c:826
 #5  0x00007ffff72c28d3 in virDomainGetMemoryParameters (domain=0x7fffd40024a0,
     params=0x7fffd40027a0, nparams=0x7fffec8bfa24, flags=0) at libvirt.c:4137
 #6  0x000055555563714d in remoteDispatchDomainGetMemoryParameters (server=0x555555eb7e00,
     client=0x555555ebaef0, msg=0x555555ebb3e0, rerr=0x7fffec8bfb70, args=0x7fffd40024e0,
     ret=0x7fffd4002420) at remote.c:1895
 #7  0x00005555556052c4 in remoteDispatchDomainGetMemoryParametersHelper (server=0x555555eb7e00,
     client=0x555555ebaef0, msg=0x555555ebb3e0, rerr=0x7fffec8bfb70, args=0x7fffd40024e0,
     ret=0x7fffd4002420) at remote_dispatch.h:4050
 #8  0x00007ffff73b293f in virNetServerProgramDispatchCall (prog=0x555555ec3ae0,
     server=0x555555eb7e00, client=0x555555ebaef0, msg=0x555555ebb3e0)
     at rpc/virnetserverprogram.c:435
 #9  0x00007ffff73b207f in virNetServerProgramDispatch (prog=0x555555ec3ae0,
     server=0x555555eb7e00, client=0x555555ebaef0, msg=0x555555ebb3e0)
     at rpc/virnetserverprogram.c:305
 #10 0x00007ffff73a4d2c in virNetServerProcessMsg (srv=0x555555eb7e00, client=0x555555ebaef0,
     prog=0x555555ec3ae0, msg=0x555555ebb3e0) at rpc/virnetserver.c:165
 #11 0x00007ffff73a4e8d in virNetServerHandleJob (jobOpaque=0x555555ebc7e0, opaque=0x555555eb7e00)
     at rpc/virnetserver.c:186
 #12 0x00007ffff7187f3f in virThreadPoolWorker (opaque=0x555555eb7ac0) at util/virthreadpool.c:144
 #13 0x00007ffff718733a in virThreadHelper (data=0x555555eb7890) at util/virthreadpthread.c:161
 #14 0x00007ffff468ed89 in start_thread (arg=0x7fffec8c0700) at pthread_create.c:308
 #15 0x00007ffff3da26bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>
(cherry picked from commit f8c1cb90)

Conflicts:
	src/lxc/lxc_driver.c

When opening a new connection to the driver, nwfilterOpen
only succeeds if the driverState has been allocated.

Move the privilege check in driver initialization before
the state allocation to disable the driver.

This changes the nwfilter-define error from:
error: cannot create config directory (null): Bad address
To:
this function is not supported by the connection driver:
virNWFilterDefineXML

https://bugzilla.redhat.com/show_bug.cgi?id=1029266
(cherry picked from commit b7829f95)