RFC Address NETFILTER_CFG issues

There were questions about the presence and cause of unsolicited syscall events in the logs containing NETFILTER_CFG records and sometimes unaccompanied NETFILTER_CFG records.

During testing at least the following list of events trigger NETFILTER_CFG records and the syscalls related (There may be more events that will trigger this message type.):
init_module, finit_module: modprobe
setsockopt: iptables-restore, ip6tables-restore, ebtables-restore
unshare: (h?)ostnamed
clone: libvirtd

The syscall events unsolicited by any audit rule were found to be caused by a missing !audit_dummy_context() check before creating a NETFILTER_CFG record. Check !audit_dummy_context() before creating the NETFILTER_CFG record.

The vast majority of unaccompanied records are caused by the fedora default
rule: "-a never,task" and the occasional early startup one is I believe caused by the iptables filter table module hard linked into the kernel rather than a loadable module. The !audit_dummy_context() check above should avoid them.

Seemingly duplicate records are not actually exact duplicates that are caused by netfilter table initialization in different network namespaces from the same syscall. Recommend adding the network namespace ID (proc inode) to the record to make this obvious.

Ebtables module initialization to register tables doesn't generate records because it was never hooked in to audit. Recommend adding audit hooks to log this.

See: https://github.com/linux-audit/audit-kernel/issues/25
See: https://github.com/linux-audit/audit-kernel/issues/35
See: https://github.com/linux-audit/audit-kernel/issues/43

Richard Guy Briggs (6):
netfilter: normalize x_table function declarations
netfilter: normalize ebtables function declarations
netfilter: audit only on xtables and ebtables syscall rule or
standalone
netfilter: ebtables: audit table registration
netfilter: add audit operation field
netfilter: add audit netns ID

 include/linux/audit.h              |    4 +-
 include/linux/netfilter/x_tables.h |    1 +
 include/uapi/linux/audit.h         |    1 +
 kernel/auditsc.c                   |    3 +-
 net/bridge/netfilter/ebtables.c    |  148 +++++++++++++++++++++++-------------
 net/ipv4/netfilter/arp_tables.c    |    2 +-
 net/ipv4/netfilter/ip_tables.c     |    2 +-
 net/ipv6/netfilter/ip6_tables.c    |    2 +-
 net/netfilter/x_tables.c           |   76 +++++++++++--------
 9 files changed, 149 insertions(+), 90 deletions(-)