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authorFlorian Westphal <fw@strlen.de>2018-08-02 21:44:41 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2018-08-16 19:37:03 +0200
commit6a48de0144767f2c6880540c0a4ac6741e3c440b (patch)
treef3111dac7df6aa291d8d8b60dcb50f5a508c9d70 /net/netfilter
parentd209df3e7f7002d9099fdb0f6df0f972b4386a63 (diff)
netfilter: nf_tables: don't prevent event handler from device cleanup on netns exit
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>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nf_tables_api.c7
-rw-r--r--net/netfilter/nft_chain_filter.c12
2 files changed, 9 insertions, 10 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 80636cc59686..1dca5683f59f 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5925,10 +5925,7 @@ static int nf_tables_flowtable_event(struct notifier_block *this,
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) {
@@ -5936,7 +5933,7 @@ static int nf_tables_flowtable_event(struct notifier_block *this,
}
}
mutex_unlock(&net->nft.commit_mutex);
- put_net(net);
+
return NOTIFY_DONE;
}
diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index 9d07b277b9ee..3fd540b2c6ba 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -293,6 +293,13 @@ static void nft_netdev_event(unsigned long event, struct net_device *dev,
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:
@@ -318,10 +325,6 @@ static int nf_tables_netdev_event(struct notifier_block *this,
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)
@@ -338,7 +341,6 @@ static int nf_tables_netdev_event(struct notifier_block *this,
}
}
mutex_unlock(&ctx.net->nft.commit_mutex);
- put_net(ctx.net);
return NOTIFY_DONE;
}