The combination of IPIP tunnel with direct xmit, eg. bridge device,
breaks because no dst_entry is provided to check the skb headroom and to
set the iph->frag_off field. This leads to invalid dst usage and can
trigger a crash in the tunnel transmit path.

Fix this by moving dst_cache and dst_cookie out of the runtime union so
that they can be shared by neighbour, xfrm, and direct tunnel flows.
For FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve
route state in these shared fields and release it through the common
dst release path.

Since dst_entry is now available to the three supported xmit modes and
dst_release() already deals with NULL dst, remove the xmit type check
in nft_flow_dst_release(). Moreover, skip the check if the dst entry
is NULL in nf_flow_dst_check() which is now the case for the direct
xmit case.

Based on patch from Rein Wei <n05ec@lzu.edu.cn>.

Fixes: d30301ba4b07 ("netfilter: flowtable: Add IPIP tx sw acceleration")
Cc: stable@vger.kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Reported-by: Zhengyang Chen <chzhengyang2023@lzu.edu.cn>
Reported-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

No driver supports for IPIP tunnels yet, give up early on setting up the
hardware offload for this scenario.

This patch adds a stub that can be enhanced to add more configuration
that are currently not supported. As of now, the offload work is
enqueued to the worker, then ignored if the hardware offload
configuration is not supported.

Check the NF_FLOW_HW flag to know if this entry was already tried once
to be offloaded so this is not retried on refresh when unsupported. Move
NF_FLOW_HW flag check to nf_flow_offload_add(). If this NF_FLOW_HW flag
is unset the _del and _stats variants are never called.

This can be updated later on to skip hardware offload work to be queued
in case hardware offload does not support it.

Fixes: d98103575dcd ("netfilter: flowtable: Add IP6IP6 rx sw acceleration")
Fixes: ab427db17885 ("netfilter: flowtable: Add IPIP rx sw acceleration")
Cc: stable@vger.kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Reported-by: Zhengyang Chen <chzhengyang2023@lzu.edu.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

Store master conntrack tuple in the expectation since exp->master might
refer to a different conntrack when accessed from rcu read side lock
area due to typesafe rcu rules.

Fixes: 02a3231b6d82 ("netfilter: nf_conntrack_expect: store netns and zone in expectation")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

IRC Direct client-to-client requires plaintext.  IRC over TLS should be
preferred, making this helper ineffective.  Add a deprecation warning and
update the help text to better reflect that this is needed for the DCC
extension, not IRC itself.

PPTP is esoteric these days and it is the only helper that requires the
destroy callback in the conntrack helper API.

Removal would simplify the conntrack core.

Both helpers are IPv4 only.

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

This patch replaces the timer API by GC worker approach for
expectations, as it already happened in many other subsystems.

Use the existing conntrack GC worker to iterate over the local list of
expectations in the master conntrack to reap expired expectations.
Check IPS_HELPER_BIT to run GC for expectations, set it on for nft_ct
expectation which nevers sets it. Hold the expectation spinlock while
iterating over the master conntrack expectation list to synchronize with
nf_ct_remove_expectations(). This also performs runtime packet path
garbage collection through the expectation insertion and lookup
functions while walking over one of the chains of the global expectation
hashtables. Unconfirmed conntrack entries are skipped since ct->ext can
be reallocated and dying are skipped since those will be gone soon.
Set on IPS_HELPER_BIT if the helper ct extension is added, then the new
GC worker does not need to bump the ct refcount to check if the ct->ext
helper is available.

This removes the extra bump on the refcount for expectation timers, this
allows to remove several nf_ct_expect_put() calls after the unlink,
after this update only refcount remains at 1 while on the expectation
hashes.

This patch implicitly addresses a race with the existing timer API
allowing an expectation to access a stale exp->master pointer which has
been already released when expectation removal loses races with an
expiring timer, ie. timer_del() reporting false.

Add a new NF_CT_EXPECT_DEAD flag to reap this expectation via GC. This
is needed by nf_conntrack_unexpect_related() which is called in error
paths to invalidate newly created expectations that has been added into
the hashes. These expectactions cannot be inmediately released as GC or
nf_ct_remove_expectations() could race to make it. On expectation
insert, the runtime GC reaps stale expectations before checking the
expectation limit set by policy.

Set current timestamp in nf_ct_expect_alloc(), then add the expectation
policy timeout (or custom timeout specified added on top of this) to
specify the expectation lifetime.

Fixes: bffcaad9afdf ("netfilter: ctnetlink: ensure safe access to master conntrack")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Blamed commit added NFT_META_BRI_IIFHWADDR to the set validate callback,
yet this is a get operation.

Add a get validate callback and move the NFT_META_BRI_IIFHWADDR key
there.

AFAICS this is harmless, NFT_META_BRI_IIFHWADDR can deal with a NULL
input device and the set handler ignores a NFT_META_BRI_IIFHWADDR
operation, but it allows to read 4 bytes off bridge skb->cb[].

Fixes: cbd2257dc96e ("netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

The br_netfilter fake rtable is embedded in struct net_bridge and is
attached to bridged packets with skb_dst_set_noref(). If such a packet is
queued to NFQUEUE, __nf_queue() upgrades that fake dst with
skb_dst_force().

At that point the queued skb can hold a real dst reference after bridge
teardown has started. The problem is not that every bridged packet needs
its own dst reference. The problem is that NFQUEUE can keep the bridge
private fake dst alive after unregister begins.

Fix this by keeping the bridge fake dst model unchanged and pinning the
bridge master device only while the packet sits in NFQUEUE. Record the
bridge device in nf_queue_entry when the queued skb carries a bridge fake
dst, take a device reference for the queue lifetime, and drop it when the
queue entry is freed.

Also make sure queued entries are reaped when that bridge device goes
down, and drop the redundant nf_bridge_info_exists() test from the fake
dst detection.

This keeps netdev_priv(br->dev) alive until verdict completion, so the
embedded fake rtable and its metrics backing storage cannot be freed out
from under dst_release(). It also avoids the constant refcount bump and
avoids using ipv4-specific dst helpers for IPv6 bridge traffic.

Fixes: 34666d467cbf ("netfilter: bridge: move br_netfilter out of the core")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Haoze Xie <royenheart@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Pablo Neira Ayuso says:

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

The following patchset contains Netfilter/IPVS updates for net-next.
More specifically, this contains conncount rework to address AI related
reports, assorted Netfiter updates and two small incremental updates on
IPVS:

1) Replace old obsolete workqueues (system_wq, system_unbound_wq)
   in IPVS, from Marco Crivellari.

2) Replace WARN_ON{_ONCE} by DEBUG_NET_WARN_ON_ONCE in nf_tables.
   In the recent years, reporters say that the use of WARN_ON{_ONCE}
   in conjunction with panic_on_warn=1 results in DoS. Let's replace
   it by DEBUG_NET_WARN_ON_ONCE so this is only exercised by test
   infrastructure and fuzzers, while also providing context to AI
   agents. From Fernando F. Mancera.

Five patches from Florian Westphal to address AI reports in the conncount
infrastructures:

3) Fix missing rcu read lock section when calling
   __ovs_ct_limit_get_zone_limit().

4) Add a dedicate lock per rbtree tree, this increases memory
   usage but it should improve scalability.

5) Add a helper function to find the rbtree node, no functional
   changes are intented.

6) Add sequence counter to detect concurrent tree modifications
   and retry lookups.

7) Add locks to GC conncount walk and address other nitpicks.

Then, several assorted updates:

8) Defensive Tree-wide addition of NULL checks for ct extensions.

9) Bail out if flowtable bypass cannot be fully set up from the
   flow offload expression, instead of lazy building a likely
   incomplete one.

10) Fix documentation for the new conn_max sysctl toggle in IPVS.

11) Add nf_dev_xmit_recursion*() helpers and use them, to address
    recent AI reports.

* tag 'nf-next-26-06-14' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  netfilter: nf_dup_netdev: add nf_dev_xmit_recursion*() helpers and use them
  ipvs: fix doc syntax for conn_max sysctl
  netfilter: flowtable: bail out if forward path cannot be discovered
  netfilter: conntrack: check NULL when retrieving ct extension
  netfilter: nf_conncount: gc and rcu fixes
  netfilter: nf_conncount: add sequence counter to detect tree modifications
  netfilter: nf_conncount: split count_tree_node rbtree walk into helper
  netfilter: nf_conncount: use per nf_conncount_data spinlocks
  netfilter: nf_conncount: callers must hold rcu read lock
  netfilter: nf_tables: use DEBUG_NET_WARN_ON_ONCE in packet and control paths
  ipvs: Replace use of system_unbound_wq with system_dfl_long_wq
====================

Link: https://patch.msgid.link/20260614114605.474783-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Update nft_dup and nft_fwd to use the nf_dev_xmit_recursion() helpers.
This patch also disables BH when transmitting the skb to address a
possible migration to different CPU leading to imbalanced decrementation
of the recursion counters.

This is modeled after Florian Westphal's dev_xmit_recursion*() API
available since commit 97cdcf37b57e ("net: place xmit recursion in
softnet data") according to its current state in the tree.

Fixes: 1d47b55b36d2 ("netfilter: nft_fwd_netdev: use recursion counter in neigh egress path")
Fixes: f37ad9127039 ("netfilter: nf_dup_netdev: Move the recursion counter struct netdev_xmit")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_ct_ext_find() might return NULL if ct extension is not found.

Add also the null checks to:

- nfct_help()
- nfct_help_data()
- nfct_seqadj()
- nfct_nat()

This is defensive, for safety reasons.

nf_ct_ext_find() used to return NULL if the extension is stale for
unconfirmed conntracks if the genid validation fails.

Skip NULL check in nf_nat_inet_fn() given this is valid to be NULL
for non-initialized ct nat extensions.

While at it, fetch ct helper area in nf_ct_expect_related_report() only
once and pass it on to other ancilliary functions. Replace WARN_ON()
by WARN_ON_ONCE() in nf_ct_unlink_expect_report().

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