commit f9a43007d3f7ba76d5e7f9421094f00f2ef202f8 upstream.
__nft_release_hooks() is called from pre_netns exit path which unregisters the hooks, then the NETDEV_UNREGISTER event is triggered which unregisters the hooks again.
[ 565.221461] WARNING: CPU: 18 PID: 193 at net/netfilter/core.c:495 __nf_unregister_net_hook+0x247/0x270 [...] [ 565.246890] CPU: 18 PID: 193 Comm: kworker/u64:1 Tainted: G E 5.18.0-rc7+ #27 [ 565.253682] Workqueue: netns cleanup_net [ 565.257059] RIP: 0010:__nf_unregister_net_hook+0x247/0x270 [...] [ 565.297120] Call Trace: [ 565.300900] <TASK> [ 565.304683] nf_tables_flowtable_event+0x16a/0x220 [nf_tables] [ 565.308518] raw_notifier_call_chain+0x63/0x80 [ 565.312386] unregister_netdevice_many+0x54f/0xb50
Unregister and destroy netdev hook from netns pre_exit via kfree_rcu so the NETDEV_UNREGISTER path see unregistered hooks.
Fixes: 767d1216bff8 ("netfilter: nftables: fix possible UAF over chains from packet path in netns") Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org --- net/netfilter/nf_tables_api.c | 34 +++++++++++++++++++++++++------- net/netfilter/nft_chain_filter.c | 3 +++ 2 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 719b30d6ec64..adab83a22f6c 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -204,9 +204,10 @@ static int nf_tables_register_hook(struct net *net, return nf_register_net_hook(net, ops); }
-static void nf_tables_unregister_hook(struct net *net, - const struct nft_table *table, - struct nft_chain *chain) +static void __nf_tables_unregister_hook(struct net *net, + const struct nft_table *table, + struct nft_chain *chain, + bool release_netdev) { const struct nft_base_chain *basechain; const struct nf_hook_ops *ops; @@ -221,6 +222,16 @@ static void nf_tables_unregister_hook(struct net *net, return basechain->type->ops_unregister(net, ops);
nf_unregister_net_hook(net, ops); + if (release_netdev && + table->family == NFPROTO_NETDEV) + nft_base_chain(chain)->ops.dev = NULL; +} + +static void nf_tables_unregister_hook(struct net *net, + const struct nft_table *table, + struct nft_chain *chain) +{ + __nf_tables_unregister_hook(net, table, chain, false); }
static int nft_trans_table_add(struct nft_ctx *ctx, int msg_type) @@ -5821,8 +5832,9 @@ nft_flowtable_type_get(struct net *net, u8 family) return ERR_PTR(-ENOENT); }
-static void nft_unregister_flowtable_net_hooks(struct net *net, - struct nft_flowtable *flowtable) +static void __nft_unregister_flowtable_net_hooks(struct net *net, + struct nft_flowtable *flowtable, + bool release_netdev) { int i;
@@ -5831,9 +5843,17 @@ static void nft_unregister_flowtable_net_hooks(struct net *net, continue;
nf_unregister_net_hook(net, &flowtable->ops[i]); + if (release_netdev) + flowtable->ops[i].dev = NULL; } }
+static void nft_unregister_flowtable_net_hooks(struct net *net, + struct nft_flowtable *flowtable) +{ + __nft_unregister_flowtable_net_hooks(net, flowtable, false); +} + static int nf_tables_newflowtable(struct net *net, struct sock *nlsk, struct sk_buff *skb, const struct nlmsghdr *nlh, @@ -7862,9 +7882,9 @@ static void __nft_release_table(struct net *net, struct nft_table *table) ctx.family = table->family;
list_for_each_entry(chain, &table->chains, list) - nf_tables_unregister_hook(net, table, chain); + __nf_tables_unregister_hook(net, table, chain, true); list_for_each_entry(flowtable, &table->flowtables, list) - nft_unregister_flowtable_net_hooks(net, flowtable); + __nft_unregister_flowtable_net_hooks(net, flowtable, true); /* No packets are walking on these chains anymore. */ ctx.table = table; list_for_each_entry(chain, &table->chains, list) { diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c index a308d45ee95e..397aa83f54e0 100644 --- a/net/netfilter/nft_chain_filter.c +++ b/net/netfilter/nft_chain_filter.c @@ -296,6 +296,9 @@ static void nft_netdev_event(unsigned long event, struct net_device *dev, if (strcmp(basechain->dev_name, dev->name) != 0) return;
+ if (!basechain->ops.dev) + return; + /* UNREGISTER events are also happpening on netns exit. * * Altough nf_tables core releases all tables/chains, only