netfilter: reduce hook array sizes to what is needed

PATCH In review Florian Westphal 2 participants 6 messages Dec 7, 2017

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Networking netfilter Ethernet bridge

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Florian Westphal

author maintainer

2017-12-07 13:06 UTC #0 lore raw

cover netfilter: reduce hook array sizes to what is needed

This series further reduces size of the hook arrays by only resevering space for the hooks that are implemented/supported (e.g., arp only supports 3 different hook points as it lacks PRE/POST_ROUTING).

Furthermore, add #ifdef guard to not declare arp/bridge/decnet hooks unless they are needed.

At least Fedora has CONFIG_DECNET=n so this even reduces size for some distro kernels.

I ran a few randconfig builds last night and it did not catch any build errors.

Florian Westphal (3):
netfilter: reduce hook array sizes to what is needed
netfilter: don't allocate space for decnet hooks unless needed
netfilter: don't allocate space for arp/bridge hooks unless needed

 include/linux/netfilter.h     |    6 ++++++
 include/net/netns/netfilter.h |   19 ++++++++++++++-----
 net/Kconfig                   |    1 +
 net/bridge/netfilter/Kconfig  |    2 ++
 net/ipv4/netfilter/Kconfig    |    2 ++
 net/netfilter/Kconfig         |    6 ++++++
 net/netfilter/core.c          |   22 ++++++++++++++++++++++
 net/netfilter/nf_queue.c      |    2 ++
 8 files changed, 55 insertions(+), 5 deletions(-)

Florian Westphal

author maintainer

2017-12-07 13:06 UTC #1 lore raw

PATCH 1/3 netfilter: reduce hook array sizes to what is needed

Not all families share the same hook count.

Can't use the corresponding ARP, BRIDGE, DECNET defines because they are defined in uapi headers and including them causes build failures.

struct net before:
/* size: 6592, cachelines: 103, members: 46 */
after:
/* size: 5952, cachelines: 93, members: 46 */

Signed-off-by Florian Westphal <[email protected]>

---
 include/net/netns/netfilter.h | 13 ++++++++-----
 net/netfilter/core.c          | 10 ++++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)

include/net/netns/netfilter.h +8 -5

index b39c563c2fce..46842a1f77fb 100644
@@ -17,11 +17,14 @@ struct netns_nf {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header *nf_log_dir_header;
 #endif
-	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];
+	struct nf_hook_entries __rcu *hooks_ipv4[NF_INET_NUMHOOKS];
+	struct nf_hook_entries __rcu *hooks_ipv6[NF_INET_NUMHOOKS];
+	/* in/out/forward only */
+	struct nf_hook_entries __rcu *hooks_arp[3];
+	/* note: 'BROUTE' isn't a real hook (called via function pointer) */
+	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+	/* also supports a 'HELLO' and 'ROUTE' type */
+	struct nf_hook_entries __rcu *hooks_decnet[NF_INET_NUMHOOKS + 2];
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 	bool			defrag_ipv4;
 #endif

net/netfilter/core.c +10 -0

index a6eaaf303be8..47e9690aea6e 100644
@@ -268,14 +268,24 @@ static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const
 	case NFPROTO_NETDEV:
 		break;
 	case NFPROTO_ARP:
+		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_arp) <= reg->hooknum))
+			return NULL;
 		return net->nf.hooks_arp + reg->hooknum;
 	case NFPROTO_BRIDGE:
+		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= reg->hooknum))
+			return NULL;
 		return net->nf.hooks_bridge + reg->hooknum;
 	case NFPROTO_IPV4:
+		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= reg->hooknum))
+			return NULL;
 		return net->nf.hooks_ipv4 + reg->hooknum;
 	case NFPROTO_IPV6:
+		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv6) <= reg->hooknum))
+			return NULL;
 		return net->nf.hooks_ipv6 + reg->hooknum;
 	case NFPROTO_DECNET:
+		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_decnet) <= reg->hooknum))
+			return NULL;
 		return net->nf.hooks_decnet + reg->hooknum;
 	default:
 		WARN_ON_ONCE(1);

Signature · 1 line

2.13.6

Pablo Neira Ayuso

maintainer

2017-12-07 13:14 UTC #2 lore raw

Quoted 27 lines · Florian Westphal

Not all families share the same hook count.
Can't use the corresponding ARP, BRIDGE, DECNET defines because they are defined in uapi headers and including them causes build failures.
struct net before:
/* size: 6592, cachelines: 103, members: 46 */
after:
/* size: 5952, cachelines: 93, members: 46 */
Signed-off-by Florian Westphal <[email protected]>
---
 include/net/netns/netfilter.h | 13 ++++++++-----
 net/netfilter/core.c          | 10 ++++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)
include/net/netns/netfilter.h +0 -3
index b39c563c2fce..46842a1f77fb 100644
@@ -17,11 +17,14 @@ struct netns_nf {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header *nf_log_dir_header;
 #endif
-	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];

include/net/netns/netfilter.h struct netns_nf { · line 27

Quoted 10 lines

include/net/netns/netfilter.h +8 -2

-	struct nf_hook_entries __rcu *hooks_bridge[NF_MAX_HOOKS];
-	struct nf_hook_entries __rcu *hooks_decnet[NF_MAX_HOOKS];
+	struct nf_hook_entries __rcu *hooks_ipv4[NF_INET_NUMHOOKS];
+	struct nf_hook_entries __rcu *hooks_ipv6[NF_INET_NUMHOOKS];
+	/* in/out/forward only */
+	struct nf_hook_entries __rcu *hooks_arp[3];
+	/* note: 'BROUTE' isn't a real hook (called via function pointer) */
+	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+	/* also supports a 'HELLO' and 'ROUTE' type */
+	struct nf_hook_entries __rcu *hooks_decnet[NF_INET_NUMHOOKS + 2];

Just a suggestion, for a follow up patch: Get rid of magic numbers and add some NF_ARP_NUMHOOKS and NF_DECNET_NUMHOOKS too, so similar definition.

Make sense to you?

Florian Westphal

author maintainer

2017-12-07 13:25 UTC #3 lore raw

Quoted 43 lines · Pablo Neira Ayuso

Quoted 27 lines · Florian Westphal
Not all families share the same hook count.
Can't use the corresponding ARP, BRIDGE, DECNET defines because they are defined in uapi headers and including them causes build failures.
struct net before:
/* size: 6592, cachelines: 103, members: 46 */
after:
/* size: 5952, cachelines: 93, members: 46 */
Signed-off-by Florian Westphal <[email protected]>
---
 include/net/netns/netfilter.h | 13 ++++++++-----
 net/netfilter/core.c          | 10 ++++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)
include/net/netns/netfilter.h +0 -3
index b39c563c2fce..46842a1f77fb 100644
@@ -17,11 +17,14 @@ struct netns_nf {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header *nf_log_dir_header;
 #endif
-	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];
include/net/netns/netfilter.h struct netns_nf { · line 27
Quoted 10 lines
include/net/netns/netfilter.h +8 -2
-	struct nf_hook_entries __rcu *hooks_bridge[NF_MAX_HOOKS];
-	struct nf_hook_entries __rcu *hooks_decnet[NF_MAX_HOOKS];
+	struct nf_hook_entries __rcu *hooks_ipv4[NF_INET_NUMHOOKS];
+	struct nf_hook_entries __rcu *hooks_ipv6[NF_INET_NUMHOOKS];
+	/* in/out/forward only */
+	struct nf_hook_entries __rcu *hooks_arp[3];
+	/* note: 'BROUTE' isn't a real hook (called via function pointer) */
+	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+	/* also supports a 'HELLO' and 'ROUTE' type */
+	struct nf_hook_entries __rcu *hooks_decnet[NF_INET_NUMHOOKS + 2];
Just a suggestion, for a follow up patch: Get rid of magic numbers and add some NF_ARP_NUMHOOKS and NF_DECNET_NUMHOOKS too, so similar definition.

Quoted 1 line

Make sense to you?

Yes, I will add new define to include/linux/netfilter_defs.h for this.

I'll send a v3.

Florian Westphal

author maintainer

2017-12-07 13:06 UTC #4 lore raw

PATCH 2/3 netfilter: don't allocate space for decnet hooks unless needed

In reply to Florian Westphal

no need to define hook points if the family isn't supported.

Signed-off-by Florian Westphal <[email protected]>

---
 include/linux/netfilter.h     | 2 ++
 include/net/netns/netfilter.h | 2 ++
 net/netfilter/core.c          | 4 ++++
 3 files changed, 8 insertions(+)

include/linux/netfilter.h +2 -0

index 9dcbcdfa3b82..ce4e91df8b56 100644
@@ -219,9 +219,11 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 	case NFPROTO_BRIDGE:
 		hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
 		break;
+#if IS_ENABLED(CONFIG_DECNET)
 	case NFPROTO_DECNET:
 		hook_head = rcu_dereference(net->nf.hooks_decnet[hook]);
 		break;
+#endif
 	default:
 		WARN_ON_ONCE(1);
 		break;

include/net/netns/netfilter.h +2 -0

index 46842a1f77fb..56100800718a 100644
@@ -23,8 +23,10 @@ struct netns_nf {
 	struct nf_hook_entries __rcu *hooks_arp[3];
 	/* note: 'BROUTE' isn't a real hook (called via function pointer) */
 	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+#if IS_ENABLED(CONFIG_DECNET)
 	/* also supports a 'HELLO' and 'ROUTE' type */
 	struct nf_hook_entries __rcu *hooks_decnet[NF_INET_NUMHOOKS + 2];
+#endif
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 	bool			defrag_ipv4;
 #endif

net/netfilter/core.c +4 -0

index 47e9690aea6e..0a28889835a7 100644
@@ -283,10 +283,12 @@ static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const
 		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv6) <= reg->hooknum))
 			return NULL;
 		return net->nf.hooks_ipv6 + reg->hooknum;
+#if IS_ENABLED(CONFIG_DECNET)
 	case NFPROTO_DECNET:
 		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_decnet) <= reg->hooknum))
 			return NULL;
 		return net->nf.hooks_decnet + reg->hooknum;
+#endif
 	default:
 		WARN_ON_ONCE(1);
 		return NULL;

@@ -573,7 +575,9 @@ static int __net_init netfilter_net_init(struct net *net)
 	__netfilter_net_init(net->nf.hooks_ipv6);
 	__netfilter_net_init(net->nf.hooks_arp);
 	__netfilter_net_init(net->nf.hooks_bridge);
+#if IS_ENABLED(CONFIG_DECNET)
 	__netfilter_net_init(net->nf.hooks_decnet);
+#endif
 
 #ifdef CONFIG_PROC_FS
 	net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",

Signature · 1 line

2.13.6

Florian Westphal

author maintainer

2017-12-07 13:06 UTC #5 lore raw

PATCH 3/3 netfilter: don't allocate space for arp/bridge hooks unless needed

In reply to Florian Westphal

no need to define hook points if the family isn't supported. Because we need these hooks for either nftables, arp/ebtables or the 'call-iptables' hack we have in the bridge layer add two new dependencies, NETFILTER_FAMILY_{ARP,BRIDGE}, and have the users select them.

Signed-off-by Florian Westphal <[email protected]>

---
 include/linux/netfilter.h     | 4 ++++
 include/net/netns/netfilter.h | 4 ++++
 net/Kconfig                   | 1 +
 net/bridge/netfilter/Kconfig  | 2 ++
 net/ipv4/netfilter/Kconfig    | 2 ++
 net/netfilter/Kconfig         | 6 ++++++
 net/netfilter/core.c          | 8 ++++++++
 net/netfilter/nf_queue.c      | 2 ++
 8 files changed, 29 insertions(+)

include/linux/netfilter.h +4 -0

index ce4e91df8b56..0e46cb43dd12 100644
@@ -213,12 +213,16 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 	case NFPROTO_IPV6:
 		hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
 		break;
+#ifdef CONFIG_NETFILTER_FAMILY_ARP
 	case NFPROTO_ARP:
 		hook_head = rcu_dereference(net->nf.hooks_arp[hook]);
 		break;
+#endif
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	case NFPROTO_BRIDGE:
 		hook_head = rcu_dereference(net->nf.hooks_bridge[hook]);
 		break;
+#endif
 #if IS_ENABLED(CONFIG_DECNET)
 	case NFPROTO_DECNET:
 		hook_head = rcu_dereference(net->nf.hooks_decnet[hook]);

include/net/netns/netfilter.h +4 -0

index 56100800718a..7a2e0ca8c198 100644
@@ -19,10 +19,14 @@ struct netns_nf {
 #endif
 	struct nf_hook_entries __rcu *hooks_ipv4[NF_INET_NUMHOOKS];
 	struct nf_hook_entries __rcu *hooks_ipv6[NF_INET_NUMHOOKS];
+#ifdef CONFIG_NETFILTER_FAMILY_ARP
 	/* in/out/forward only */
 	struct nf_hook_entries __rcu *hooks_arp[3];
+#endif
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	/* note: 'BROUTE' isn't a real hook (called via function pointer) */
 	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+#endif
 #if IS_ENABLED(CONFIG_DECNET)
 	/* also supports a 'HELLO' and 'ROUTE' type */
 	struct nf_hook_entries __rcu *hooks_decnet[NF_INET_NUMHOOKS + 2];

net/Kconfig +1 -0

index 9dba2715919d..842dfedbc621 100644
@@ -182,6 +182,7 @@ config BRIDGE_NETFILTER
 	depends on BRIDGE
 	depends on NETFILTER && INET
 	depends on NETFILTER_ADVANCED
+	select NETFILTER_FAMILY_BRIDGE
 	default m
 	---help---
 	  Enabling this option will let arptables resp. iptables see bridged

net/bridge/netfilter/Kconfig +2 -0

index e7ef1a1ef3a6..225d1668dfdd 100644
@@ -4,6 +4,7 @@
 #
 menuconfig NF_TABLES_BRIDGE
 	depends on BRIDGE && NETFILTER && NF_TABLES
+	select NETFILTER_FAMILY_BRIDGE
 	tristate "Ethernet Bridge nf_tables support"
 
 if NF_TABLES_BRIDGE

@@ -29,6 +30,7 @@ endif # NF_TABLES_BRIDGE
 menuconfig BRIDGE_NF_EBTABLES
 	tristate "Ethernet Bridge tables (ebtables) support"
 	depends on BRIDGE && NETFILTER && NETFILTER_XTABLES
+	select NETFILTER_FAMILY_BRIDGE
 	help
 	  ebtables is a general, extensible frame/packet identification
 	  framework. Say 'Y' or 'M' here if you want to do Ethernet

net/ipv4/netfilter/Kconfig +2 -0

index c11eb1744ab1..cee51045e2f7 100644
@@ -72,6 +72,7 @@ endif # NF_TABLES_IPV4
 
 config NF_TABLES_ARP
 	tristate "ARP nf_tables support"
+	select NETFILTER_FAMILY_ARP
 	help
 	  This option enables the ARP support for nf_tables.

@@ -392,6 +393,7 @@ endif # IP_NF_IPTABLES
 config IP_NF_ARPTABLES
 	tristate "ARP tables support"
 	select NETFILTER_XTABLES
+	select NETFILTER_FAMILY_ARP
 	depends on NETFILTER_ADVANCED
 	help
 	  arptables is a general, extensible packet identification framework.

net/netfilter/Kconfig +6 -0

index e4a13cc8a2e7..263609a7e010 100644
@@ -12,6 +12,12 @@ config NETFILTER_INGRESS
 config NETFILTER_NETLINK
 	tristate
 
+config NETFILTER_FAMILY_BRIDGE
+	bool
+
+config NETFILTER_FAMILY_ARP
+	bool
+
 config NETFILTER_NETLINK_ACCT
 tristate "Netfilter NFACCT over NFNETLINK interface"
 	depends on NETFILTER_ADVANCED

net/netfilter/core.c +8 -0

index 0a28889835a7..6337797b096e 100644
@@ -267,14 +267,18 @@ static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const
 	switch (reg->pf) {
 	case NFPROTO_NETDEV:
 		break;
+#ifdef CONFIG_NETFILTER_FAMILY_ARP
 	case NFPROTO_ARP:
 		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_arp) <= reg->hooknum))
 			return NULL;
 		return net->nf.hooks_arp + reg->hooknum;
+#endif
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	case NFPROTO_BRIDGE:
 		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= reg->hooknum))
 			return NULL;
 		return net->nf.hooks_bridge + reg->hooknum;
+#endif
 	case NFPROTO_IPV4:
 		if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= reg->hooknum))
 			return NULL;

@@ -573,8 +577,12 @@ static int __net_init netfilter_net_init(struct net *net)
 {
 	__netfilter_net_init(net->nf.hooks_ipv4);
 	__netfilter_net_init(net->nf.hooks_ipv6);
+#ifdef CONFIG_NETFILTER_FAMILY_ARP
 	__netfilter_net_init(net->nf.hooks_arp);
+#endif
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	__netfilter_net_init(net->nf.hooks_bridge);
+#endif
 #if IS_ENABLED(CONFIG_DECNET)
 	__netfilter_net_init(net->nf.hooks_decnet);
 #endif

net/netfilter/nf_queue.c +2 -0

index 836aeb08686e..0c02fdb7efc9 100644
@@ -204,8 +204,10 @@ static unsigned int nf_iterate(struct sk_buff *skb,
 static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum)
 {
 	switch (pf) {
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	case NFPROTO_BRIDGE:
 		return rcu_dereference(net->nf.hooks_bridge[hooknum]);
+#endif
 	case NFPROTO_IPV4:
 		return rcu_dereference(net->nf.hooks_ipv4[hooknum]);
 	case NFPROTO_IPV6:

Signature · 1 line

2.13.6