The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f9a43007d3f7ba76d5e7f9421094f00f2ef202f8 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso pablo@netfilter.org Date: Mon, 30 May 2022 18:24:06 +0200 Subject: [PATCH] netfilter: nf_tables: double hook unregistration in netns path

__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

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index f77414e13de1..746be13438ef 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -222,12 +222,18 @@ static int nft_netdev_register_hooks(struct net *net, }

static void nft_netdev_unregister_hooks(struct net *net, - struct list_head *hook_list) + struct list_head *hook_list, + bool release_netdev) { - struct nft_hook *hook; + struct nft_hook *hook, *next;

- list_for_each_entry(hook, hook_list, list) + list_for_each_entry_safe(hook, next, hook_list, list) { nf_unregister_net_hook(net, &hook->ops); + if (release_netdev) { + list_del(&hook->list); + kfree_rcu(hook, rcu); + } + } }

static int nf_tables_register_hook(struct net *net, @@ -253,9 +259,10 @@ static int nf_tables_register_hook(struct net *net, return nf_register_net_hook(net, &basechain->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) { struct nft_base_chain *basechain; const struct nf_hook_ops *ops; @@ -270,11 +277,19 @@ static void nf_tables_unregister_hook(struct net *net, return basechain->type->ops_unregister(net, ops);

if (nft_base_chain_netdev(table->family, basechain->ops.hooknum)) - nft_netdev_unregister_hooks(net, &basechain->hook_list); + nft_netdev_unregister_hooks(net, &basechain->hook_list, + release_netdev); else nf_unregister_net_hook(net, &basechain->ops); }

+static void nf_tables_unregister_hook(struct net *net, + const struct nft_table *table, + struct nft_chain *chain) +{ + return __nf_tables_unregister_hook(net, table, chain, false); +} + static void nft_trans_commit_list_add_tail(struct net *net, struct nft_trans *trans) { struct nftables_pernet *nft_net = nft_pernet(net); @@ -7307,13 +7322,25 @@ static void nft_unregister_flowtable_hook(struct net *net, FLOW_BLOCK_UNBIND); }

-static void nft_unregister_flowtable_net_hooks(struct net *net, - struct list_head *hook_list) +static void __nft_unregister_flowtable_net_hooks(struct net *net, + struct list_head *hook_list, + bool release_netdev) { - struct nft_hook *hook; + struct nft_hook *hook, *next;

- list_for_each_entry(hook, hook_list, list) + list_for_each_entry_safe(hook, next, hook_list, list) { nf_unregister_net_hook(net, &hook->ops); + if (release_netdev) { + list_del(&hook->list); + kfree_rcu(hook); + } + } +} + +static void nft_unregister_flowtable_net_hooks(struct net *net, + struct list_head *hook_list) +{ + __nft_unregister_flowtable_net_hooks(net, hook_list, false); }

static int nft_register_flowtable_net_hooks(struct net *net, @@ -9755,9 +9782,10 @@ static void __nft_release_hook(struct net *net, struct nft_table *table) struct nft_chain *chain;

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->hook_list); + __nft_unregister_flowtable_net_hooks(net, &flowtable->hook_list, + true); }

static void __nft_release_hooks(struct net *net)