Be sure that lists initialized in net_init hook was return to initial
state.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't currently harmful.

However, for some features it is necessary to instrument reads and
writes separately, which is not possible with ACCESS_ONCE(). This
distinction is critical to correct operation.

It's possible to transform the bulk of kernel code using the Coccinelle
script below. However, this doesn't handle comments, leaving references
to ACCESS_ONCE() instances which have been removed. As a preparatory
step, this patch converts netlink and netfilter code and comments to use
{READ,WRITE}_ONCE() consistently.

----
virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Florian Westphal <fw@strlen.de>
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-7-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

When skb is queued to userspace it leaves softirq/rcu protection.
skb->nfct (via conntrack extensions such as helper) could then reference
modules that no longer exist if the conntrack was not yet confirmed.

nf_ct_iterate_destroy() will set the DYING bit for unconfirmed
conntracks, we therefore solve this race as follows:

1. take the queue spinlock.
2. check if the conntrack is unconfirmed and has dying bit set.
   In this case, we must discard skb while we're still inside
   rcu read-side section.
3. If nf_ct_iterate_destroy() is called right after the packet is queued
   to userspace, it will be removed from the queue via
   nf_ct_iterate_destroy -> nf_queue_nf_hook_drop.

When userspace sends the verdict (nfnetlink takes rcu read lock), there
are two cases to consider:

1. nf_ct_iterate_destroy() was called while packet was out.
   In this case, skb will have been removed from the queue already
   and no reinject takes place as we won't find a matching entry for the
   packet id.

2. nf_ct_iterate_destroy() gets called right after verdict callback
   found and removed the skb from queue list.

   In this case, skb->nfct is marked as dying but it is still valid.
   The skb will be dropped either in nf_conntrack_confirm (we don't
   insert DYING conntracks into hash table) or when we try to queue
   the skb again, but either events don't occur before the rcu read lock
   is dropped.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

This patch removes duplicate rcu_read_lock().

1. IPVS part:

According to Julian Anastasov's mention, contexts of ipvs are described
at: http://marc.info/?l=netfilter-devel&m=149562884514072&w=2, in summary:

 - packet RX/TX: does not need locks because packets come from hooks.
 - sync msg RX: backup server uses RCU locks while registering new
   connections.
 - ip_vs_ctl.c: configuration get/set, RCU locks needed.
 - xt_ipvs.c: It is a netfilter match, running from hook context.

As result, rcu_read_lock and rcu_read_unlock can be removed from:

 - ip_vs_core.c: all
 - ip_vs_ctl.c:
   - only from ip_vs_has_real_service
 - ip_vs_ftp.c: all
 - ip_vs_proto_sctp.c: all
 - ip_vs_proto_tcp.c: all
 - ip_vs_proto_udp.c: all
 - ip_vs_xmit.c: all (contains only packet processing)

2. Netfilter part:

There are three types of functions that are guaranteed the rcu_read_lock().
First, as result, functions are only called by nf_hook():

 - nf_conntrack_broadcast_help(), pptp_expectfn(), set_expected_rtp_rtcp().
 - tcpmss_reverse_mtu(), tproxy_laddr4(), tproxy_laddr6().
 - match_lookup_rt6(), check_hlist(), hashlimit_mt_common().
 - xt_osf_match_packet().

Second, functions that caller already held the rcu_read_lock().
 - destroy_conntrack(), ctnetlink_conntrack_event().
 - ctnl_timeout_find_get(), nfqnl_nf_hook_drop().

Third, functions that are mixed with type1 and type2.

These functions are called by nf_hook() also these are called by
ordinary functions that already held the rcu_read_lock():

 - __ctnetlink_glue_build(), ctnetlink_expect_event().
 - ctnetlink_proto_size().

Applied files are below:

- nf_conntrack_broadcast.c, nf_conntrack_core.c, nf_conntrack_netlink.c.
- nf_conntrack_pptp.c, nf_conntrack_sip.c, nfnetlink_cttimeout.c.
- nfnetlink_queue.c, xt_TCPMSS.c, xt_TPROXY.c, xt_addrtype.c.
- xt_connlimit.c, xt_hashlimit.c, xt_osf.c

Detailed calltrace can be found at:
http://marc.info/?l=netfilter-devel&m=149667610710350&w=2

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Pablo Neira Ayuso says:

====================
Netfilter updates for net-next

The following patchset contains Netfilter updates for your net-next
tree. This batch contains connection tracking updates for the cleanup
iteration path, patches from Florian Westphal:

X) Skip unconfirmed conntracks in nf_ct_iterate_cleanup_net(), just set
   dying bit to let the CPU release them.

X) Add nf_ct_iterate_destroy() to be used on module removal, to kill
   conntrack from all namespace.

X) Restart iteration on hashtable resizing, since both may occur at
   the same time.

X) Use the new nf_ct_iterate_destroy() to remove conntrack with NAT
   mapping on module removal.

X) Use nf_ct_iterate_destroy() to remove conntrack entries helper
   module removal, from Liping Zhang.

X) Use nf_ct_iterate_cleanup_net() to remove the timeout extension
   if user requests this, also from Liping.

X) Add net_ns_barrier() and use it from FTP helper, so make sure
   no concurrent namespace removal happens at the same time while
   the helper module is being removed.

X) Use NFPROTO_MAX in layer 3 conntrack protocol array, to reduce
   module size. Same thing in nf_tables.

Updates for the nf_tables infrastructure:

X) Prepare usage of the extended ACK reporting infrastructure for
   nf_tables.

X) Remove unnecessary forward declaration in nf_tables hash set.

X) Skip set size estimation if number of element is not specified.

X) Changes to accomodate a (faster) unresizable hash set implementation,
   for anonymous sets and dynamic size fixed sets with no timeouts.

X) Faster lookup function for unresizable hash table for 2 and 4
   bytes key.

And, finally, a bunch of asorted small updates and cleanups:

X) Do not hold reference to netdev from ipt_CLUSTER, instead subscribe
   to device events and look up for index from the packet path, this
   is fixing an issue that is present since the very beginning, patch
   from Xin Long.

X) Use nf_register_net_hook() in ipt_CLUSTER, from Florian Westphal.

X) Use ebt_invalid_target() whenever possible in the ebtables tree,
   from Gao Feng.

X) Calm down compilation warning in nf_dup infrastructure, patch from
   stephen hemminger.

X) Statify functions in nftables rt expression, also from stephen.

X) Update Makefile to use canonical method to specify nf_tables-objs.
   From Jike Song.

X) Use nf_conntrack_helpers_register() in amanda and H323.

X) Space cleanup for ctnetlink, from linzhang.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Pass down struct netlink_ext_ack as parameter to all of our nfnetlink
subsystem callbacks, so we can work on follow up patches to provide
finer grain error reporting using the new infrastructure that
2d4bc93368f5 ("netlink: extended ACK reporting") provides.

No functional change, just pass down this new object to callbacks.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.

Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:

    @@
    expression SKB, LEN;
    typedef u8;
    identifier fn = { skb_put, __skb_put };
    @@
    - *(fn(SKB, LEN))
    + *(u8 *)fn(SKB, LEN)

    @@
    expression E, SKB, LEN;
    identifier fn = { skb_put, __skb_put };
    type T;
    @@
    - E = ((T *)(fn(SKB, LEN)))
    + E = fn(SKB, LEN)

which actually doesn't cover pskb_put since there are only three
users overall.

A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pablo Neira Ayuso says:

====================
Netfilter/IPVS updates for net-next

The following patchset contains Netfilter updates for your net-next
tree. A large bunch of code cleanups, simplify the conntrack extension
codebase, get rid of the fake conntrack object, speed up netns by
selective synchronize_net() calls. More specifically, they are:

1) Check for ct->status bit instead of using nfct_nat() from IPVS and
   Netfilter codebase, patch from Florian Westphal.

2) Use kcalloc() wherever possible in the IPVS code, from Varsha Rao.

3) Simplify FTP IPVS helper module registration path, from Arushi Singhal.

4) Introduce nft_is_base_chain() helper function.

5) Enforce expectation limit from userspace conntrack helper,
   from Gao Feng.

6) Add nf_ct_remove_expect() helper function, from Gao Feng.

7) NAT mangle helper function return boolean, from Gao Feng.

8) ctnetlink_alloc_expect() should only work for conntrack with
   helpers, from Gao Feng.

9) Add nfnl_msg_type() helper function to nfnetlink to build the
   netlink message type.

10) Get rid of unnecessary cast on void, from simran singhal.

11) Use seq_puts()/seq_putc() instead of seq_printf() where possible,
    also from simran singhal.

12) Use list_prev_entry() from nf_tables, from simran signhal.

13) Remove unnecessary & on pointer function in the Netfilter and IPVS
    code.

14) Remove obsolete comment on set of rules per CPU in ip6_tables,
    no longer true. From Arushi Singhal.

15) Remove duplicated nf_conntrack_l4proto_udplite4, from Gao Feng.

16) Remove unnecessary nested rcu_read_lock() in
    __nf_nat_decode_session(). Code running from hooks are already
    guaranteed to run under RCU read side.

17) Remove deadcode in nf_tables_getobj(), from Aaron Conole.

18) Remove double assignment in nf_ct_l4proto_pernet_unregister_one(),
    also from Aaron.

19) Get rid of unsed __ip_set_get_netlink(), from Aaron Conole.

20) Don't propagate NF_DROP error to userspace via ctnetlink in
    __nf_nat_alloc_null_binding() function, from Gao Feng.

21) Revisit nf_ct_deliver_cached_events() to remove unnecessary checks,
    from Gao Feng.

22) Kill the fake untracked conntrack objects, use ctinfo instead to
    annotate a conntrack object is untracked, from Florian Westphal.

23) Remove nf_ct_is_untracked(), now obsolete since we have no
    conntrack template anymore, from Florian.

24) Add event mask support to nft_ct, also from Florian.

25) Move nf_conn_help structure to
    include/net/netfilter/nf_conntrack_helper.h.

26) Add a fixed 32 bytes scratchpad area for conntrack helpers.
    Thus, we don't deal with variable conntrack extensions anymore.
    Make sure userspace conntrack helper doesn't go over that size.
    Remove variable size ct extension infrastructure now this code
    got no more clients. From Florian Westphal.

27) Restore offset and length of nf_ct_ext structure to 8 bytes now
    that wraparound is not possible any longer, also from Florian.

28) Allow to get rid of unassured flows under stress in conntrack,
    this applies to DCCP, SCTP and TCP protocols, from Florian.

29) Shrink size of nf_conntrack_ecache structure, from Florian.

30) Use TCP_MAX_WSCALE instead of hardcoded 14 in TCP tracker,
    from Gao Feng.

31) Register SYNPROXY hooks on demand, from Florian Westphal.

32) Use pernet hook whenever possible, instead of global hook
    registration, from Florian Westphal.

33) Pass hook structure to ebt_register_table() to consolidate some
    infrastructure code, from Florian Westphal.

34) Use consume_skb() and return NF_STOLEN, instead of NF_DROP in the
    SYNPROXY code, to make sure device stats are not fooled, patch
    from Gao Feng.

35) Remove NF_CT_EXT_F_PREALLOC this kills quite some code that we
    don't need anymore if we just select a fixed size instead of
    expensive runtime time calculation of this. From Florian.

36) Constify nf_ct_extend_register() and nf_ct_extend_unregister(),
    from Florian.

37) Simplify nf_ct_ext_add(), this kills nf_ct_ext_create(), from
    Florian.

38) Attach NAT extension on-demand from masquerade and pptp helper
    path, from Florian.

39) Get rid of useless ip_vs_set_state_timeout(), from Aaron Conole.

40) Speed up netns by selective calls of synchronize_net(), from
    Florian Westphal.

41) Silence stack size warning gcc in 32-bit arch in snmp helper,
    from Florian.

42) Inconditionally call nf_ct_ext_destroy(), even if we have no
    extensions, to deal with the NF_NAT_MANIP_SRC case. Patch from
    Liping Zhang.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

nf_unregister_net_hook(s) can avoid a second call to synchronize_net,
provided there is no nfqueue active in that net namespace (which is
the common case).

This also gets rid of the extra arg to nf_queue_nf_hook_drop(), normally
this gets called during netns cleanup so no packets should be queued.

For the rare case of base chain being unregistered or module removal
while nfqueue is in use the extra hiccup due to the packet drops isn't
a big deal.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Pass the new extended ACK reporting struct to all of the generic
netlink parsing functions. For now, pass NULL in almost all callers
(except for some in the core.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>