diff options
| author | Florian Westphal <fw@strlen.de> | 2018-08-02 21:44:41 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-08-16 19:37:03 +0200 |
| commit | 6a48de0144767f2c6880540c0a4ac6741e3c440b (patch) | |
| tree | f3111dac7df6aa291d8d8b60dcb50f5a508c9d70 /net | |
| parent | d209df3e7f7002d9099fdb0f6df0f972b4386a63 (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')
| -rw-r--r-- | net/netfilter/nf_tables_api.c | 7 | ||||
| -rw-r--r-- | net/netfilter/nft_chain_filter.c | 12 |
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; } |