Customers using GKE 1.25 and 1.26 are facing conntrack issues
root caused to commit c9c3b6811f74 ("netfilter: conntrack: make
max chain length random").

Even if we assume Uniform Hashing, a bucket often reachs 8 chained
items while the load factor of the hash table is smaller than 0.5

With a limit of 16, we reach load factors of 3.
With a limit of 32, we reach load factors of 11.
With a limit of 40, we reach load factors of 15.
With a limit of 50, we reach load factors of 24.

This patch changes MIN_CHAINLEN to 50, to minimize risks.

Ideally, we could in the future add a cushion based on expected
load factor (2 * nf_conntrack_max / nf_conntrack_buckets),
because some setups might expect unusual values.

Fixes: c9c3b6811f74 ("netfilter: conntrack: make max chain length random")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

It seems that change was unintentional, we have userspace code that
needs the mark while listening for events like REPLY, DESTROY, etc.
Also include 0-marks in requested dumps, as they were before that fix.

Fixes: 1feeae071507 ("netfilter: ctnetlink: fix compilation warning after data race fixes in ct mark")
Signed-off-by: Ivan Delalande <colona@arista.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

If the ruleset contains consumed quota, restore them accordingly.
Otherwise, listing after restoration shows never used items.

Restore the user-defined quota and flags too.

Fixes: ed0a0c60f0e5 ("netfilter: nft_quota: move stateful fields out of expression data")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

If the ruleset contains last timestamps, restore them accordingly.
Otherwise, listing after restoration shows never used items.

Fixes: 33a24de37e81 ("netfilter: nft_last: move stateful fields out of expression data")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

1) Fix broken listing of set elements when table has an owner.

2) Fix conntrack refcount leak in ctnetlink with related conntrack
   entries, from Hangyu Hua.

3) Fix use-after-free/double-free in ctnetlink conntrack insert path,
   from Florian Westphal.

4) Fix ip6t_rpfilter with VRF, from Phil Sutter.

5) Fix use-after-free in ebtables reported by syzbot, also from Florian.

6) Use skb->len in xt_length to deal with IPv6 jumbo packets,
   from Xin Long.

7) Fix NETLINK_LISTEN_ALL_NSID with ctnetlink, from Florian Westphal.

8) Fix memleak in {ip_,ip6_,arp_}tables in ENOMEM error case,
   from Pavel Tikhomirov.

* git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: x_tables: fix percpu counter block leak on error path when creating new netns
  netfilter: ctnetlink: make event listener tracking global
  netfilter: xt_length: use skb len to match in length_mt6
  netfilter: ebtables: fix table blob use-after-free
  netfilter: ip6t_rpfilter: Fix regression with VRF interfaces
  netfilter: conntrack: fix rmmod double-free race
  netfilter: ctnetlink: fix possible refcount leak in ctnetlink_create_conntrack()
  netfilter: nf_tables: allow to fetch set elements when table has an owner
====================

Link: https://lore.kernel.org/r/20230222092137.88637-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

pernet tracking doesn't work correctly because other netns might have
set NETLINK_LISTEN_ALL_NSID on its event socket.

In this case its expected that events originating in other net
namespaces are also received.

Making pernet-tracking work while also honoring NETLINK_LISTEN_ALL_NSID
requires much more intrusive changes both in netlink and nfnetlink,
f.e. adding a 'setsockopt' callback that lets nfnetlink know that the
event socket entered (or left) ALL_NSID mode.

Move to global tracking instead: if there is an event socket anywhere
on the system, all net namespaces which have conntrack enabled and
use autobind mode will allocate the ecache extension.

netlink_has_listeners() returns false only if the given group has no
subscribers in any net namespace, the 'net' argument passed to
nfnetlink_has_listeners is only used to derive the protocol (nfnetlink),
it has no other effect.

For proper NETLINK_LISTEN_ALL_NSID-aware pernet tracking of event
listeners a new netlink_has_net_listeners() is also needed.

Fixes: 90d1daa45849 ("netfilter: conntrack: add nf_conntrack_events autodetect mode")
Reported-by: Bryce Kahle <bryce.kahle@datadoghq.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

For IPv6 Jumbo packets, the ipv6_hdr(skb)->payload_len is always 0,
and its real payload_len ( > 65535) is saved in hbh exthdr. With 0
length for the jumbo packets, it may mismatch.

To fix this, we can just use skb->len instead of parsing exthdrs, as
the hbh exthdr parsing has been done before coming to length_mt6 in
ip6_rcv_core() and br_validate_ipv6() and also the packet has been
trimmed according to the correct IPv6 (ext)hdr length there, and skb
len is trustable in length_mt6().

Note that this patch is especially needed after the IPv6 BIG TCP was
supported in kernel, which is using IPv6 Jumbo packets. Besides, to
match the packets greater than 65535 more properly, a v1 revision of
xt_length may be needed to extend "min, max" to u32 in the future,
and for now the IPv6 Jumbo packets can be matched by:

  # ip6tables -m length ! --length 0:65535

Fixes: 7c4e983c4f3c ("net: allow gso_max_size to exceed 65536")
Fixes: 0fe79f28bfaf ("net: allow gro_max_size to exceed 65536")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_conntrack_hash_check_insert() callers free the ct entry directly, via
nf_conntrack_free.

This isn't safe anymore because
nf_conntrack_hash_check_insert() might place the entry into the conntrack
table and then delteted the entry again because it found that a conntrack
extension has been removed at the same time.

In this case, the just-added entry is removed again and an error is
returned to the caller.

Problem is that another cpu might have picked up this entry and
incremented its reference count.

This results in a use-after-free/double-free, once by the other cpu and
once by the caller of nf_conntrack_hash_check_insert().

Fix this by making nf_conntrack_hash_check_insert() not fail anymore
after the insertion, just like before the 'Fixes' commit.

This is safe because a racing nf_ct_iterate() has to wait for us
to release the conntrack hash spinlocks.

While at it, make the function return -EAGAIN in the rmmod (genid
changed) case, this makes nfnetlink replay the command (suggested
by Pablo Neira).

Fixes: c56716c69ce1 ("netfilter: extensions: introduce extension genid count")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_ct_put() needs to be called to put the refcount got by
nf_conntrack_find_get() to avoid refcount leak when
nf_conntrack_hash_check_insert() fails.

Fixes: 7d367e06688d ("netfilter: ctnetlink: fix soft lockup when netlink adds new entries (v2)")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Pablo Neira Ayuso says:

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

The following patchset contains Netfilter updates for net-next:

1) Add safeguard to check for NULL tupe in objects updates via
   NFT_MSG_NEWOBJ, this should not ever happen. From Alok Tiwari.

2) Incorrect pointer check in the new destroy rule command,
   from Yang Yingliang.

3) Incorrect status bitcheck in nf_conntrack_udp_packet(),
   from Florian Westphal.

4) Simplify seq_print_acct(), from Ilia Gavrilov.

5) Use 2-arg optimal variant of kfree_rcu() in IPVS,
   from Julian Anastasov.

6) TCP connection enters CLOSE state in conntrack for locally
   originated TCP reset packet from the reject target,
   from Florian Westphal.

The fixes #2 and #3 in this series address issues from the previous pull
nf-next request in this net-next cycle.
====================

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