This is a note to let you know that I've just added the patch titled netfilter: arp_tables: add pre_exit hook for table unregister to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: netfilter-arp_tables-add-pre_exit-hook-for-table-unregister.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d163a925ebbc6eb5b562b0f1d72c7e817aa75c40 Mon Sep 17 00:00:00 2001 From: Florian Westphal <fw@xxxxxxxxx> Date: Wed, 7 Apr 2021 21:43:40 +0200 Subject: netfilter: arp_tables: add pre_exit hook for table unregister From: Florian Westphal <fw@xxxxxxxxx> commit d163a925ebbc6eb5b562b0f1d72c7e817aa75c40 upstream. Same problem that also existed in iptables/ip(6)tables, when arptable_filter is removed there is no longer a wait period before the table/ruleset is free'd. Unregister the hook in pre_exit, then remove the table in the exit function. This used to work correctly because the old nf_hook_unregister API did unconditional synchronize_net. The per-net hook unregister function uses call_rcu instead. Fixes: b9e69e127397 ("netfilter: xtables: don't hook tables by default") Signed-off-by: Florian Westphal <fw@xxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/netfilter_arp/arp_tables.h | 5 +++-- net/ipv4/netfilter/arp_tables.c | 9 +++++++-- net/ipv4/netfilter/arptable_filter.c | 10 +++++++++- 3 files changed, 19 insertions(+), 5 deletions(-) --- a/include/linux/netfilter_arp/arp_tables.h +++ b/include/linux/netfilter_arp/arp_tables.h @@ -52,8 +52,9 @@ extern void *arpt_alloc_initial_table(co int arpt_register_table(struct net *net, const struct xt_table *table, const struct arpt_replace *repl, const struct nf_hook_ops *ops, struct xt_table **res); -void arpt_unregister_table(struct net *net, struct xt_table *table, - const struct nf_hook_ops *ops); +void arpt_unregister_table(struct net *net, struct xt_table *table); +void arpt_unregister_table_pre_exit(struct net *net, struct xt_table *table, + const struct nf_hook_ops *ops); extern unsigned int arpt_do_table(struct sk_buff *skb, const struct nf_hook_state *state, struct xt_table *table); --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -1541,10 +1541,15 @@ out_free: return ret; } -void arpt_unregister_table(struct net *net, struct xt_table *table, - const struct nf_hook_ops *ops) +void arpt_unregister_table_pre_exit(struct net *net, struct xt_table *table, + const struct nf_hook_ops *ops) { nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks)); +} +EXPORT_SYMBOL(arpt_unregister_table_pre_exit); + +void arpt_unregister_table(struct net *net, struct xt_table *table) +{ __arpt_unregister_table(net, table); } --- a/net/ipv4/netfilter/arptable_filter.c +++ b/net/ipv4/netfilter/arptable_filter.c @@ -56,16 +56,24 @@ static int __net_init arptable_filter_ta return err; } +static void __net_exit arptable_filter_net_pre_exit(struct net *net) +{ + if (net->ipv4.arptable_filter) + arpt_unregister_table_pre_exit(net, net->ipv4.arptable_filter, + arpfilter_ops); +} + static void __net_exit arptable_filter_net_exit(struct net *net) { if (!net->ipv4.arptable_filter) return; - arpt_unregister_table(net, net->ipv4.arptable_filter, arpfilter_ops); + arpt_unregister_table(net, net->ipv4.arptable_filter); net->ipv4.arptable_filter = NULL; } static struct pernet_operations arptable_filter_net_ops = { .exit = arptable_filter_net_exit, + .pre_exit = arptable_filter_net_pre_exit, }; static int __init arptable_filter_init(void) Patches currently in stable-queue which might be from fw@xxxxxxxxx are queue-5.11/netfilter-bridge-add-pre_exit-hooks-for-ebtable-unregistration.patch queue-5.11/netfilter-arp_tables-add-pre_exit-hook-for-table-unregister.patch