netfilter: xt_qtaguid: fix error exit that would keep a spinlock.

qtudev_open() could return with a uid_tag_data_tree_lock held
when an kzalloc(..., GFP_ATOMIC) would fail.
Very unlikely to get triggered AND survive the mayhem of running out of mem.

Signed-off-by: JP Abgrall <jpa@google.com>
netfilter: qtaguid: Don't BUG_ON if create_if_tag_stat fails

If create_if_tag_stat fails to allocate memory (GFP_ATOMIC) the
following will happen:

qtaguid: iface_stat: tag stat alloc failed
...
kernel BUG at xt_qtaguid.c:1482!

Signed-off-by: Pontus Fuchs <pontus.fuchs@gmail.com>
netfilter: xt_qtaguid: remove AID_* dependency for access control

qtaguid limits what can be done with /ctrl and /stats based on group
membership.
This changes removes AID_NET_BW_STATS and AID_NET_BW_ACCT, and picks
up the groups from the gid of the matching proc entry files.

Signed-off-by: JP Abgrall <jpa@google.com>
Change-Id: I42e477adde78a12ed5eb58fbc0b277cdaadb6f94
netfilter: xt_qtaguid: extend iface stat to report protocols

In the past the iface_stat_fmt would only show global bytes/packets
for the skb-based numbers.
For stall detection in userspace, distinguishing tcp vs other protocols
makes it easier.
Now we report
  ifname total_skb_rx_bytes total_skb_rx_packets total_skb_tx_bytes
  total_skb_tx_packets {rx,tx}_{tcp,udp,ohter}_{bytes,packets}

Bug: 6818637
Signed-off-by: JP Abgrall <jpa@google.com>
Change-Id: I179c5ebf2fe822acec0bce4973b4bbb5e7d5076d
netfilter: xt_qtaguid: Allow tracking loopback

In the past it would always ignore interfaces with loopback addresses.
Now we just treat them like any other.
This also helps with writing tests that check for the presence
of the qtaguid module.

Signed-off-by: JP Abgrall <jpa@google.com>