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:
0a2cf5ee432c2 ("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>
if (event != NETDEV_UNREGISTER)
return 0;
- net = maybe_get_net(dev_net(dev));
- if (!net)
- return 0;
-
+ net = dev_net(dev);
mutex_lock(&net->nft.commit_mutex);
list_for_each_entry(table, &net->nft.tables, list) {
list_for_each_entry(flowtable, &table->flowtables, list) {
}
}
mutex_unlock(&net->nft.commit_mutex);
- put_net(net);
+
return NOTIFY_DONE;
}
if (strcmp(basechain->dev_name, dev->name) != 0)
return;
+ /* UNREGISTER events are also happpening on netns exit.
+ *
+ * Altough nf_tables core releases all tables/chains, only
+ * this event handler provides guarantee that
+ * basechain.ops->dev is still accessible, so we cannot
+ * skip exiting net namespaces.
+ */
__nft_release_basechain(ctx);
break;
case NETDEV_CHANGENAME:
event != NETDEV_CHANGENAME)
return NOTIFY_DONE;
- ctx.net = maybe_get_net(ctx.net);
- if (!ctx.net)
- return NOTIFY_DONE;
-
mutex_lock(&ctx.net->nft.commit_mutex);
list_for_each_entry(table, &ctx.net->nft.tables, list) {
if (table->family != NFPROTO_NETDEV)
}
}
mutex_unlock(&ctx.net->nft.commit_mutex);
- put_net(ctx.net);
return NOTIFY_DONE;
}