linux-stable.git/net/netfilter/nf_queue.c, branch v6.6.147

netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst

2026-07-24T14:03:32+00:00

commit c9c9b37f8c5505224e8d206184df3bb668ee00cf upstream.

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 
Reported-by: Yifan Wu 
Reported-by: Juefei Pu 
Reported-by: Xin Liu 
Signed-off-by: Haoze Xie 
Signed-off-by: Ren Wei 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_queue: hold bridge skb->dev while queued

2026-06-01T15:43:07+00:00

commit e196115ec330a18de415bdb9f5071aa9f08e53ce upstream.

br_pass_frame_up() rewrites skb->dev from the ingress port to the bridge
master before queueing bridge LOCAL_IN packets. NFQUEUE only holds
references on state.in/out and bridge physdevs, so a queued bridge
packet can retain a freed bridge master in skb->dev until reinjection.

When the verdict is reinjected later, br_netif_receive_skb() re-enters
the receive path with skb->dev still pointing at the freed bridge master,
triggering a use-after-free.

Store skb->dev in the queue entry, hold a reference on it for the queue
lifetime, and use the saved device when dropping queued packets during
NETDEV_DOWN handling.

Fixes: ac2863445686 ("netfilter: bridge: add nf_afinfo to enable queuing to userspace")
Cc: stable@kernel.org
Reported-by: Yuan Tan 
Reported-by: Yifan Wu 
Reported-by: Juefei Pu 
Reported-by: Xin Liu 
Signed-off-by: Haoze Xie 
Signed-off-by: Ren Wei 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: propagate net to nf_bridge_get_physindev

2024-01-25T23:35:59+00:00

[ Upstream commit a54e72197037d2c9bfcd70dddaac8c8ccb5b41ba ]

This is a preparation patch for replacing physindev with physinif on
nf_bridge_info structure. We will use dev_get_by_index_rcu to resolve
device, when needed, and it requires net to be available.

Signed-off-by: Pavel Tikhomirov 
Reviewed-by: Simon Horman 
Signed-off-by: Pablo Neira Ayuso 
Stable-dep-of: 9874808878d9 ("netfilter: bridge: replace physindev with physinif in nf_bridge_info")
Signed-off-by: Sasha Levin

netfilter: nf_queue: remove excess nf_bridge variable

2024-01-25T23:35:59+00:00

[ Upstream commit aeaa44075f8e49e2e0ad4507d925e690b7950145 ]

We don't really need nf_bridge variable here. And nf_bridge_info_exists
is better replacement for nf_bridge_info_get in case we are only
checking for existence.

Signed-off-by: Pavel Tikhomirov 
Reviewed-by: Simon Horman 
Signed-off-by: Pablo Neira Ayuso 
Stable-dep-of: 9874808878d9 ("netfilter: bridge: replace physindev with physinif in nf_bridge_info")
Signed-off-by: Sasha Levin

netfilter: nf_queue: handle socket prefetch

2022-03-01T10:51:15+00:00

In case someone combines bpf socket assign and nf_queue, then we will
queue an skb who references a struct sock that did not have its
reference count incremented.

As we leave rcu protection, there is no guarantee that skb->sk is still
valid.

For refcount-less skb->sk case, try to increment the reference count
and then override the destructor.

In case of failure we have two choices: orphan the skb and 'delete'
preselect or let nf_queue() drop the packet.

Do the latter, it should not happen during normal operation.

Fixes: cf7fbe660f2d ("bpf: Add socket assign support")
Acked-by: Joe Stringer 
Signed-off-by: Florian Westphal

netfilter: nf_queue: fix possible use-after-free

2022-03-01T10:50:35+00:00

Eric Dumazet says:
  The sock_hold() side seems suspect, because there is no guarantee
  that sk_refcnt is not already 0.

On failure, we cannot queue the packet and need to indicate an
error.  The packet will be dropped by the caller.

v2: split skb prefetch hunk into separate change

Fixes: 271b72c7fa82c ("udp: RCU handling for Unicast packets.")
Reported-by: Eric Dumazet 
Reviewed-by: Eric Dumazet 
Signed-off-by: Florian Westphal

netfilter: nf_queue: don't assume sk is full socket

2022-03-01T10:48:18+00:00

There is no guarantee that state->sk refers to a full socket.

If refcount transitions to 0, sock_put calls sk_free which then ends up
with garbage fields.

I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
debug work and pointing out state->sk oddities.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Tested-by: Oleksandr Natalenko 
Signed-off-by: Florian Westphal

Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next

2021-08-11T09:22:26+00:00

Pablo Neira Ayuso says:

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

The following patchset contains Netfilter updates for net-next:

1) Use nfnetlink_unicast() instead of netlink_unicast() in nft_compat.

2) Remove call to nf_ct_l4proto_find() in flowtable offload timeout
   fixup.

3) CLUSTERIP registers ARP hook on demand, from Florian.

4) Use clusterip_net to store pernet warning, also from Florian.

5) Remove struct netns_xt, from Florian Westphal.

6) Enable ebtables hooks in initns on demand, from Florian.

7) Allow to filter conntrack netlink dump per status bits,
   from Florian Westphal.

8) Register x_tables hooks in initns on demand, from Florian.

9) Remove queue_handler from per-netns structure, again from Florian.
====================

Signed-off-by: David S. Miller

netfilter: nf_queue: move hookfn registration out of struct net

2021-08-10T15:32:00+00:00

This was done to detect when the pernet->init() function was not called
yet, by checking if net->nf.queue_handler is NULL.

Once the nfnetlink_queue module is active, all struct net pointers
contain the same address.  So place this back in nf_queue.c.

Handle the 'netns error unwind' test by checking nfnl_queue_net for a
NULL pointer and add a comment for this.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

net: Remove redundant if statements

2021-08-05T12:27:50+00:00

The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.

Signed-off-by: Yajun Deng 
Signed-off-by: David S. Miller