Commit c67ef53a authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Jakub Kicinski
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netfilter: br_netfilter: Use nested-BH locking for brnf_frag_data_storage. 



brnf_frag_data_storage is a per-CPU variable and relies on disabled BH
for its locking. Without per-CPU locking in local_bh_disable() on
PREEMPT_RT this data structure requires explicit locking.

Add a local_lock_t to the data structure and use local_lock_nested_bh()
for locking. This change adds only lockdep coverage and does not alter
the functional behaviour for !PREEMPT_RT.

Cc: Florian Westphal <fw@strlen.de>
Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: bridge@lists.linux.dev
Cc: coreteam@netfilter.org
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-8-bigeasy@linutronix.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent ebad6d03

net/bridge/br_netfilter_hooks.c

+16 −4
Original line number Diff line number Diff line
@@ -137,6 +137,7 @@ static inline bool is_pppoe_ipv6(const struct sk_buff *skb, 
#define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)



struct brnf_frag_data {

	local_lock_t bh_lock;

	char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];

	u8 encap_size;

	u8 size;
@@ -144,7 +145,9 @@ struct brnf_frag_data { 
	__be16 vlan_proto;

};



static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);

static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage) = {

	.bh_lock = INIT_LOCAL_LOCK(bh_lock),

};



static void nf_bridge_info_free(struct sk_buff *skb)

{
@@ -850,6 +853,7 @@ static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff 
{

	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);

	unsigned int mtu, mtu_reserved;

	int ret;



	mtu_reserved = nf_bridge_mtu_reduction(skb);

	mtu = skb->dev->mtu;
@@ -882,6 +886,7 @@ static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff 


		IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;



		local_lock_nested_bh(&brnf_frag_data_storage.bh_lock);

		data = this_cpu_ptr(&brnf_frag_data_storage);



		if (skb_vlan_tag_present(skb)) {
@@ -897,7 +902,9 @@ static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff 
		skb_copy_from_linear_data_offset(skb, -data->size, data->mac,

						 data->size);



		return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);

		ret = br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);

		local_unlock_nested_bh(&brnf_frag_data_storage.bh_lock);

		return ret;

	}

	if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&

	    skb->protocol == htons(ETH_P_IPV6)) {
@@ -909,6 +916,7 @@ static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff 


		IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;



		local_lock_nested_bh(&brnf_frag_data_storage.bh_lock);

		data = this_cpu_ptr(&brnf_frag_data_storage);

		data->encap_size = nf_bridge_encap_header_len(skb);

		data->size = ETH_HLEN + data->encap_size;
@@ -916,8 +924,12 @@ static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff 
		skb_copy_from_linear_data_offset(skb, -data->size, data->mac,

						 data->size);



		if (v6ops)

			return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);

		if (v6ops) {

			ret = v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);

			local_unlock_nested_bh(&brnf_frag_data_storage.bh_lock);

			return ret;

		}

		local_unlock_nested_bh(&brnf_frag_data_storage.bh_lock);



		kfree_skb(skb);

		return -EMSGSIZE;