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Commit b0f38338 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: reduce size of hook entry point locations 



struct net contains:

struct nf_hook_entries __rcu *hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];

which store the hook entry point locations for the various protocol
families and the hooks.

Using array results in compact c code when doing accesses, i.e.
  x = rcu_dereference(net->nf.hooks[pf][hook]);

but its also wasting a lot of memory, as most families are
not used.

So split the array into those families that are used, which
are only 5 (instead of 13).  In most cases, the 'pf' argument is
constant, i.e. gcc removes switch statement.

struct net before:
 /* size: 5184, cachelines: 81, members: 46 */
after:
 /* size: 4672, cachelines: 73, members: 46 */

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 8c873e21

include/linux/netfilter.h

+22 −2
Original line number Diff line number Diff line
@@ -195,7 +195,7 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net, 
			  struct net_device *indev, struct net_device *outdev,

			  int (*okfn)(struct net *, struct sock *, struct sk_buff *))

{

	struct nf_hook_entries *hook_head;

	struct nf_hook_entries *hook_head = NULL;

	int ret = 1;



#ifdef HAVE_JUMP_LABEL
@@ -206,7 +206,27 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net, 
#endif



	rcu_read_lock();

	hook_head = rcu_dereference(net->nf.hooks[pf][hook]);

	switch (pf) {

	case NFPROTO_IPV4:

		hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);

		break;

	case NFPROTO_IPV6:

		hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);

		break;

	case NFPROTO_ARP:

		hook_head = rcu_dereference(net->nf.hooks_arp[hook]);

		break;

	case NFPROTO_BRIDGE:

		hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);

		break;

	case NFPROTO_DECNET:

		hook_head = rcu_dereference(net->nf.hooks_decnet[hook]);

		break;

	default:

		WARN_ON_ONCE(1);

		break;

	}



	if (hook_head) {

		struct nf_hook_state state;

include/net/netns/netfilter.h

+5 −1
Original line number Diff line number Diff line
@@ -17,7 +17,11 @@ struct netns_nf { 
#ifdef CONFIG_SYSCTL

	struct ctl_table_header *nf_log_dir_header;

#endif

	struct nf_hook_entries __rcu *hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];

	struct nf_hook_entries __rcu *hooks_ipv4[NF_MAX_HOOKS];

	struct nf_hook_entries __rcu *hooks_ipv6[NF_MAX_HOOKS];

	struct nf_hook_entries __rcu *hooks_arp[NF_MAX_HOOKS];

	struct nf_hook_entries __rcu *hooks_bridge[NF_MAX_HOOKS];

	struct nf_hook_entries __rcu *hooks_decnet[NF_MAX_HOOKS];

#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)

	bool			defrag_ipv4;

#endif

net/bridge/br_netfilter_hooks.c

+1 −1
Original line number Diff line number Diff line
@@ -991,7 +991,7 @@ int br_nf_hook_thresh(unsigned int hook, struct net *net, 
	unsigned int i;

	int ret;



	e = rcu_dereference(net->nf.hooks[NFPROTO_BRIDGE][hook]);

	e = rcu_dereference(net->nf.hooks_bridge[hook]);

	if (!e)

		return okfn(net, sk, skb);

net/netfilter/core.c

+30 −8
Original line number Diff line number Diff line
@@ -264,8 +264,23 @@ static void *__nf_hook_entries_try_shrink(struct nf_hook_entries __rcu **pp) 


static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const struct nf_hook_ops *reg)

{

	if (reg->pf != NFPROTO_NETDEV)

		return net->nf.hooks[reg->pf]+reg->hooknum;

	switch (reg->pf) {

	case NFPROTO_NETDEV:

		break;

	case NFPROTO_ARP:

		return net->nf.hooks_arp + reg->hooknum;

	case NFPROTO_BRIDGE:

		return net->nf.hooks_bridge + reg->hooknum;

	case NFPROTO_IPV4:

		return net->nf.hooks_ipv4 + reg->hooknum;

	case NFPROTO_IPV6:

		return net->nf.hooks_ipv6 + reg->hooknum;

	case NFPROTO_DECNET:

		return net->nf.hooks_decnet + reg->hooknum;

	default:

		WARN_ON_ONCE(1);

		return NULL;

	}



#ifdef CONFIG_NETFILTER_INGRESS

	if (reg->hooknum == NF_NETDEV_INGRESS) {
@@ -534,15 +549,22 @@ void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *); 
EXPORT_SYMBOL(nf_nat_decode_session_hook);

#endif



static int __net_init netfilter_net_init(struct net *net)

static void __net_init __netfilter_net_init(struct nf_hook_entries *e[NF_MAX_HOOKS])

{

	int i, h;

	int h;



	for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) {

	for (h = 0; h < NF_MAX_HOOKS; h++)

			RCU_INIT_POINTER(net->nf.hooks[i][h], NULL);

		RCU_INIT_POINTER(e[h], NULL);

}



static int __net_init netfilter_net_init(struct net *net)

{

	__netfilter_net_init(net->nf.hooks_ipv4);

	__netfilter_net_init(net->nf.hooks_ipv6);

	__netfilter_net_init(net->nf.hooks_arp);

	__netfilter_net_init(net->nf.hooks_bridge);

	__netfilter_net_init(net->nf.hooks_decnet);



#ifdef CONFIG_PROC_FS

	net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",

						net->proc_net);

net/netfilter/nf_queue.c

+19 −2
Original line number Diff line number Diff line
@@ -201,6 +201,23 @@ static unsigned int nf_iterate(struct sk_buff *skb, 
	return NF_ACCEPT;

}



static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum)

{

	switch (pf) {

	case NFPROTO_BRIDGE:

		return rcu_dereference(net->nf.hooks_bridge[hooknum]);

	case NFPROTO_IPV4:

		return rcu_dereference(net->nf.hooks_ipv4[hooknum]);

	case NFPROTO_IPV6:

		return rcu_dereference(net->nf.hooks_ipv6[hooknum]);

	default:

		WARN_ON_ONCE(1);

		return NULL;

	}



	return NULL;

}



/* Caller must hold rcu read-side lock */

void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)

{
@@ -216,12 +233,12 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 
	net = entry->state.net;

	pf = entry->state.pf;



	hooks = rcu_dereference(net->nf.hooks[pf][entry->state.hook]);

	hooks = nf_hook_entries_head(net, pf, entry->state.hook);



	nf_queue_entry_release_refs(entry);



	i = entry->hook_index;

	if (WARN_ON_ONCE(i >= hooks->num_hook_entries)) {

	if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) {

		kfree_skb(skb);

		kfree(entry);

		return;