When a netnsamespace exits, the nf_tables pernet_ops will remove all rules.
However, there is one caveat:
Base chains that register ingress hooks will cause use-after-free:
device is already gone at that point.
The device event handlers prevent this from happening:
netns exit synthesizes unregister events for all devices.
However, an improper fix for a race condition made the notifiers a no-op
in case they get called from netns exit path, so revert that part.
This is safe now as the previous patch fixed nf_tables pernet ops
and device notifier initialisation ordering.
Fixes: 0a2cf5ee43 ("netfilter: nf_tables: close race between netns exit and rmmod")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
We must register nfnetlink ops last, as that exposes nf_tables to
userspace. Without this, we could theoretically get nfnetlink request
before net->nft state has been initialized.
Fixes: 99633ab29b ("netfilter: nf_tables: complete net namespace support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Continue to use nftnl subsys mutex to protect (un)registration of hook types,
expressions and so on, but force batch operations to do their own
locking.
This allows distinct net namespaces to perform transactions in parallel.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
If net namespace is exiting while nf_tables module is being removed
we can oops:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
IP: nf_tables_flowtable_event+0x43/0xf0 [nf_tables]
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
Modules linked in: nf_tables(-) nfnetlink [..]
unregister_netdevice_notifier+0xdd/0x130
nf_tables_module_exit+0x24/0x3a [nf_tables]
SyS_delete_module+0x1c5/0x240
do_syscall_64+0x74/0x190
Avoid this by attempting to take reference on the net namespace from
the notifiers. If it fails the namespace is exiting already, and nft
core is taking care of cleanup work.
We also need to make sure the netdev hook type gets removed
before netns ops removal, else notifier might be invoked with device
event for a netns where net->nft was never initialised (because
pernet ops was removed beforehand).
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
One module per supported filter chain family type takes too much memory
for very little code - too much modularization - place all chain filter
definitions in one single file.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Florian Westphal