Description of problem:
I'm trying to define LXC domain with network. libvirt show error:Requested operation is not valid: System lacks NETNS support, but I have kernel with support for all namespaces. The same domain without network starts correctly.
Problem does not occur when I use version 1.2.2.

Version-Release number of selected component (if applicable):
libvirt-1.2.3 build from sources
iproute-3.12.0-2.fc21.i686
kernel-3.14.0-0.rc5.git0.1.fc21.1.i686
selinux-policy-3.13.1-41.fc21.noarch

How reproducible:
Always

Steps to Reproduce:
1. # cat /etc/libvirt/lxc/container.xml
<domain type='lxc'>
  <name>mycontainer</name>
  <uuid>d750af59-6082-437c-b860-922e76b46410</uuid>
  <memory unit='KiB'>819200</memory>
  <currentMemory unit='KiB'>819200</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='i686'>exe</type>
    <init>/usr/lib/systemd/systemd</init>
  </os>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <filesystem type='mount' accessmode='passthrough'>
      <source dir='/var/lib/libvirt/filesystems/mycontainer'/>
      <target dir='/'/>
    </filesystem>
    <interface type="network">
        <source network="default"/>
        </interface>
    <console type='pty'>
      <target type='lxc' port='0'/>
    </console>
  </devices>
</domain>
2. # virsh --connect lxc:/// define /etc/libvirt/lxc/container.xml

Actual results:
error: Failed to define domain from /etc/libvirt/lxc/container.xml
error: Requested operation is not valid: System lacks NETNS support

Expected results:
LXC domain will be created.

Additional info:
I have found that the same error was reported 3 months ago:
https://bugzilla.redhat.com/show_bug.cgi?id=1050210
I was trying Selinux in enforcing and permissive mode, but that doesn't help at all. Here are AVC log messages:
type=SYSCALL msg=audit(01/04/14 13:00:08.106:817) : arch=i386 syscall=execve success=yes exit=0 a0=0xa256de8 a1=0xa0283f8 a2=0xa27a2e8 a3=0x1 items=0 ppid=564 pid=1962 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=iptables exe=/usr/sbin/xtables-multi subj=system_u:system_r:iptables_t:s0 key=(null) 
type=AVC msg=audit(01/04/14 13:00:08.106:817) : avc:  denied  { noatsecure } for  pid=1962 comm=iptables scontext=system_u:system_r:firewalld_t:s0 tcontext=system_u:system_r:iptables_t:s0 tclass=process 
type=AVC msg=audit(01/04/14 13:00:08.106:817) : avc:  denied  { siginh } for  pid=1962 comm=iptables scontext=system_u:system_r:firewalld_t:s0 tcontext=system_u:system_r:iptables_t:s0 tclass=process 
type=AVC msg=audit(01/04/14 13:00:08.106:817) : avc:  denied  { rlimitinh } for  pid=1962 comm=iptables scontext=system_u:system_r:firewalld_t:s0 tcontext=system_u:system_r:iptables_t:s0 tclass=process