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netfilter: reduce hook array sizes

PATCH New Florian Westphal 1 participant 6 messages Dec 7, 2017

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Florian Westphal

author maintainer
#0 lore raw

v3 cover netfilter: reduce hook array sizes

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.

See individual patches for changes since v2.

Florian Westphal (5):
netfilter: add defines for arp/decnet max hooks
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
netfilter: reduce NF_MAX_HOOKS define

 include/linux/netfilter.h             |    6 +++++
 include/linux/netfilter_defs.h        |   12 ++++++++++-
 include/net/netns/netfilter.h         |   16 ++++++++++-----
 include/uapi/linux/netfilter_arp.h    |    3 ++
 include/uapi/linux/netfilter_decnet.h |    4 ++-
 net/Kconfig                           |    1 
 net/bridge/netfilter/Kconfig          |    2 +
 net/ipv4/netfilter/Kconfig            |    2 +
 net/netfilter/Kconfig                 |    6 +++++
 net/netfilter/core.c                  |   36 +++++++++++++++++++++++++++-------
 net/netfilter/nf_queue.c              |    2 +
 11 files changed, 76 insertions(+), 14 deletions(-)
author maintainer
#1 lore raw

PATCH v3 1/5 netfilter: add defines for arp/decnet max hooks

The kernel already has defines for this, but they are in uapi exposed headers.

Including these from netns.h causes build errors and also adds unneeded dependencies on heads that we don't need.

So move these defines to netfilter_defs.h and place the uapi ones in ifndef __KERNEL__ to keep them for userspace.

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

---
new in v3.

 include/linux/netfilter_defs.h        | 6 ++++++
 include/uapi/linux/netfilter_arp.h    | 3 +++
 include/uapi/linux/netfilter_decnet.h | 4 +++-
 3 files changed, 12 insertions(+), 1 deletion(-)
include/linux/netfilter_defs.h +6 -0
index dc6111adea06..fdcdf2bf34df 100644
@@ -7,4 +7,10 @@
 /* Largest hook number + 1, see uapi/linux/netfilter_decnet.h */
 #define NF_MAX_HOOKS 8
 
+/* in/out/forward only */
+#define NF_ARP_NUMHOOKS 3
+
+/* max hook is NF_DN_ROUTE (6), also see uapi/linux/netfilter_decnet.h */
+#define NF_DN_NUMHOOKS 7
+
 #endif
include/uapi/linux/netfilter_arp.h +3 -0
index 81b6a4cbcb72..791dfc5ae907 100644
@@ -15,6 +15,9 @@
 #define NF_ARP_IN	0
 #define NF_ARP_OUT	1
 #define NF_ARP_FORWARD	2
+
+#ifndef __KERNEL__
 #define NF_ARP_NUMHOOKS	3
+#endif
 
 #endif /* __LINUX_ARP_NETFILTER_H */
include/uapi/linux/netfilter_decnet.h +3 -1
index 9089c38f6abe..61f1c7dfd033 100644
@@ -24,6 +24,9 @@
 #define NFC_DN_IF_IN		0x0004
 /* Output device. */
 #define NFC_DN_IF_OUT		0x0008
+
+/* kernel define is in netfilter_defs.h */
+#define NF_DN_NUMHOOKS		7
 #endif /* ! __KERNEL__ */
 
 /* DECnet Hooks */

@@ -41,7 +44,6 @@
 #define NF_DN_HELLO		5
 /* Input Routing Packets */
 #define NF_DN_ROUTE		6
-#define NF_DN_NUMHOOKS		7
 
 enum nf_dn_hook_priorities {
 	NF_DN_PRI_FIRST = INT_MIN,
Signature · 1 line
2.13.6
author maintainer
#2 lore raw

PATCH v3 2/5 netfilter: reduce hook array sizes to what is needed

In reply to Florian Westphal

Not all families share the same hook count, adjust sizes to what is needed.

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

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

---
changes since v2:
- use ARP/DN defines instead of magic number in struct netns_nf
- fix __netfilter_net_init to use correct size, not NF_MAX_HOOKS

 include/net/netns/netfilter.h | 10 +++++-----
 net/netfilter/core.c          | 24 +++++++++++++++++-------
 2 files changed, 22 insertions(+), 12 deletions(-)
include/net/netns/netfilter.h +5 -5
index b39c563c2fce..8f756a4b9205 100644
@@ -17,11 +17,11 @@ 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];
+	struct nf_hook_entries __rcu *hooks_arp[NF_ARP_NUMHOOKS];
+	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+	struct nf_hook_entries __rcu *hooks_decnet[NF_DN_NUMHOOKS];
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 	bool			defrag_ipv4;
 #endif
net/netfilter/core.c +17 -7
index a6eaaf303be8..43643427b560 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);

@@ -549,21 +559,21 @@ void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
 EXPORT_SYMBOL(nf_nat_decode_session_hook);
 #endif
 
-static void __net_init __netfilter_net_init(struct nf_hook_entries *e[NF_MAX_HOOKS])
+static void __net_init __netfilter_net_init(struct nf_hook_entries **e, int max)
 {
 	int h;
 
-	for (h = 0; h < NF_MAX_HOOKS; h++)
+	for (h = 0; h < max; h++)
 		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);
+	__netfilter_net_init(net->nf.hooks_ipv4, ARRAY_SIZE(net->nf.hooks_ipv4));
+	__netfilter_net_init(net->nf.hooks_ipv6, ARRAY_SIZE(net->nf.hooks_ipv6));
+	__netfilter_net_init(net->nf.hooks_arp, ARRAY_SIZE(net->nf.hooks_arp));
+	__netfilter_net_init(net->nf.hooks_bridge, ARRAY_SIZE(net->nf.hooks_bridge));
+	__netfilter_net_init(net->nf.hooks_decnet, ARRAY_SIZE(net->nf.hooks_decnet));
 
 #ifdef CONFIG_PROC_FS
 	net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
Signature · 1 line
2.13.6
author maintainer
#3 lore raw

PATCH v3 3/5 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]>

---
changes since v2:
split this from a different patch.

 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 8f756a4b9205..432609fd9899 100644
@@ -21,7 +21,9 @@ struct netns_nf {
 	struct nf_hook_entries __rcu *hooks_ipv6[NF_INET_NUMHOOKS];
 	struct nf_hook_entries __rcu *hooks_arp[NF_ARP_NUMHOOKS];
 	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+#if IS_ENABLED(CONFIG_DECNET)
 	struct nf_hook_entries __rcu *hooks_decnet[NF_DN_NUMHOOKS];
+#endif
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 	bool			defrag_ipv4;
 #endif
net/netfilter/core.c +4 -0
index 43643427b560..4738d0d0ebac 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, ARRAY_SIZE(net->nf.hooks_ipv6));
 	__netfilter_net_init(net->nf.hooks_arp, ARRAY_SIZE(net->nf.hooks_arp));
 	__netfilter_net_init(net->nf.hooks_bridge, ARRAY_SIZE(net->nf.hooks_bridge));
+#if IS_ENABLED(CONFIG_DECNET)
 	__netfilter_net_init(net->nf.hooks_decnet, ARRAY_SIZE(net->nf.hooks_decnet));
+#endif
 
 #ifdef CONFIG_PROC_FS
 	net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
Signature · 1 line
2.13.6
author maintainer
#4 lore raw

PATCH v3 4/5 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]>

---
changes since v2:
split this from a different patch.

 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 432609fd9899..ca043342c0eb 100644
@@ -19,8 +19,12 @@ 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
 	struct nf_hook_entries __rcu *hooks_arp[NF_ARP_NUMHOOKS];
+#endif
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	struct nf_hook_entries __rcu *hooks_bridge[NF_INET_NUMHOOKS];
+#endif
 #if IS_ENABLED(CONFIG_DECNET)
 	struct nf_hook_entries __rcu *hooks_decnet[NF_DN_NUMHOOKS];
 #endif
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 4738d0d0ebac..ed8618f4efd7 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, ARRAY_SIZE(net->nf.hooks_ipv4));
 	__netfilter_net_init(net->nf.hooks_ipv6, ARRAY_SIZE(net->nf.hooks_ipv6));
+#ifdef CONFIG_NETFILTER_FAMILY_ARP
 	__netfilter_net_init(net->nf.hooks_arp, ARRAY_SIZE(net->nf.hooks_arp));
+#endif
+#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 	__netfilter_net_init(net->nf.hooks_bridge, ARRAY_SIZE(net->nf.hooks_bridge));
+#endif
 #if IS_ENABLED(CONFIG_DECNET)
 	__netfilter_net_init(net->nf.hooks_decnet, ARRAY_SIZE(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
author maintainer
#5 lore raw

PATCH v3 5/5 netfilter: reduce NF_MAX_HOOKS define

In reply to Florian Westphal

This can be same as NF_INET_NUMHOOKS if we don't support DECNET.

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

---
new in v3.

 include/linux/netfilter_defs.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
include/linux/netfilter_defs.h +7 -3
index fdcdf2bf34df..8dddfb151f00 100644
@@ -4,13 +4,17 @@
 
 #include <uapi/linux/netfilter.h>
 
-/* Largest hook number + 1, see uapi/linux/netfilter_decnet.h */
-#define NF_MAX_HOOKS 8
-
 /* in/out/forward only */
 #define NF_ARP_NUMHOOKS 3
 
 /* max hook is NF_DN_ROUTE (6), also see uapi/linux/netfilter_decnet.h */
 #define NF_DN_NUMHOOKS 7
 
+#if IS_ENABLED(CONFIG_DECNET)
+/* Largest hook number + 1, see uapi/linux/netfilter_decnet.h */
+#define NF_MAX_HOOKS	NF_DN_NUMHOOKS
+#else
+#define NF_MAX_HOOKS	NF_INET_NUMHOOKS
+#endif
+
 #endif
Signature · 1 line
2.13.6