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netfilter: add a xt_FLOWOFFLOAD target for NAT/routing offload support

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This makes it possible to add an iptables rule that offloads routing/NAT
packet processing to a software fast path. This fast path is much
quicker than running packets through the regular tables/chains.

Requires Linux 4.14

Signed-off-by: Felix Fietkau <nbd@nbd.name>
master
Felix Fietkau 7 years ago
parent 1033356442
commit 820f030998
4 changed files with 479 additions and 1 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 3
      include/netfilter.mk
  2. 13
      package/kernel/linux/modules/netfilter.mk
  3. 18
      package/network/utils/iptables/patches/800-flowoffload_target.patch
  4. 446
      target/linux/generic/hack-4.14/650-netfilter-add-xt_OFFLOAD-target.patch

3
include/netfilter.mk
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@ -143,6 +143,8 @@ $(eval $(call nf_add,IPT_IPSEC,CONFIG_IP_NF_MATCH_AH, $(P_V4)ipt_ah))
$(eval $(call nf_add,IPT_IPSEC,CONFIG_NETFILTER_XT_MATCH_ESP, $(P_XT)xt_esp))
$(eval $(call nf_add,IPT_IPSEC,CONFIG_NETFILTER_XT_MATCH_POLICY, $(P_XT)xt_policy))
# flow offload support
$(eval $(call nf_add,IPT_FLOW,CONFIG_NETFILTER_XT_TARGET_FLOWOFFLOAD, $(P_XT)xt_FLOWOFFLOAD))
# IPv6
@ -370,6 +372,7 @@ IPT_BUILTIN += $(IPT_CONNTRACK-y)
IPT_BUILTIN += $(IPT_CONNTRACK_EXTRA-y)
IPT_BUILTIN += $(IPT_EXTRA-y)
IPT_BUILTIN += $(IPT_FILTER-y)
IPT_BUILTIN += $(IPT_FLOW-y) $(IPT_FLOW-m)
IPT_BUILTIN += $(IPT_IPOPT-y)
IPT_BUILTIN += $(IPT_IPRANGE-y)
IPT_BUILTIN += $(IPT_CLUSTER-y)

13
package/kernel/linux/modules/netfilter.mk
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@ -147,7 +147,7 @@ define KernelPackage/nf-flow
CONFIG_NETFILTER_INGRESS=y \
CONFIG_NF_FLOW_TABLE \
CONFIG_NF_FLOW_TABLE_HW
DEPENDS:=+kmod-nf-conntrack +kmod-nft-core @!LINUX_3_18 @!LINUX_4_4 @!LINUX_4_9
DEPENDS:=+kmod-nf-conntrack @!LINUX_3_18 @!LINUX_4_4 @!LINUX_4_9
FILES:= \
$(LINUX_DIR)/net/netfilter/nf_flow_table.ko \
$(LINUX_DIR)/net/netfilter/nf_flow_table_hw.ko
@ -237,6 +237,17 @@ endef
$(eval $(call KernelPackage,ipt-filter))
define KernelPackage/ipt-offload
TITLE:=Netfilter routing/NAT offload support
KCONFIG:=CONFIG_NETFILTER_XT_TARGET_FLOWOFFLOAD
FILES:=$(foreach mod,$(IPT_FLOW-m),$(LINUX_DIR)/net/$(mod).ko)
AUTOLOAD:=$(call AutoProbe,$(notdir $(IPT_FLOW-m)))
$(call AddDepends/ipt,+kmod-nf-flow)
endef
$(eval $(call KernelPackage,ipt-offload))
define KernelPackage/ipt-ipopt
TITLE:=Modules for matching/changing IP packet options
KCONFIG:=$(KCONFIG_IPT_IPOPT)

18
package/network/utils/iptables/patches/800-flowoffload_target.patch
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@ -0,0 +1,18 @@
--- /dev/null
+++ b/extensions/libxt_FLOWOFFLOAD.c
@@ -0,0 +1,15 @@
+#include <xtables.h>
+
+static struct xtables_target offload_tg_reg[] = {
+ {
+ .family = NFPROTO_UNSPEC,
+ .name = "FLOWOFFLOAD",
+ .revision = 0,
+ .version = XTABLES_VERSION,
+ },
+};
+
+void _init(void)
+{
+ xtables_register_targets(offload_tg_reg, ARRAY_SIZE(offload_tg_reg));
+}

446
target/linux/generic/hack-4.14/650-netfilter-add-xt_OFFLOAD-target.patch
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@ -0,0 +1,446 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Tue, 20 Feb 2018 15:56:02 +0100
Subject: [PATCH] netfilter: add xt_OFFLOAD target
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
create mode 100644 net/netfilter/xt_OFFLOAD.c
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -75,8 +75,6 @@ config NF_TABLES_ARP
help
This option enables the ARP support for nf_tables.
-endif # NF_TABLES
-
config NF_FLOW_TABLE_IPV4
tristate "Netfilter flow table IPv4 module"
depends on NF_FLOW_TABLE
@@ -85,6 +83,8 @@ config NF_FLOW_TABLE_IPV4
To compile it as a module, choose M here.
+endif # NF_TABLES
+
config NF_DUP_IPV4
tristate "Netfilter IPv4 packet duplication to alternate destination"
depends on !NF_CONNTRACK || NF_CONNTRACK
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -69,7 +69,6 @@ config NFT_FIB_IPV6
multicast or blackhole.
endif # NF_TABLES_IPV6
-endif # NF_TABLES
config NF_FLOW_TABLE_IPV6
tristate "Netfilter flow table IPv6 module"
@@ -79,6 +78,8 @@ config NF_FLOW_TABLE_IPV6
To compile it as a module, choose M here.
+endif # NF_TABLES
+
config NF_DUP_IPV6
tristate "Netfilter IPv6 packet duplication to alternate destination"
depends on !NF_CONNTRACK || NF_CONNTRACK
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -665,8 +665,6 @@ config NFT_FIB_NETDEV
endif # NF_TABLES_NETDEV
-endif # NF_TABLES
-
config NF_FLOW_TABLE_INET
tristate "Netfilter flow table mixed IPv4/IPv6 module"
depends on NF_FLOW_TABLE
@@ -675,11 +673,12 @@ config NF_FLOW_TABLE_INET
To compile it as a module, choose M here.
+endif # NF_TABLES
+
config NF_FLOW_TABLE
tristate "Netfilter flow table module"
depends on NETFILTER_INGRESS
depends on NF_CONNTRACK
- depends on NF_TABLES
help
This option adds the flow table core infrastructure.
@@ -968,6 +967,15 @@ config NETFILTER_XT_TARGET_NOTRACK
depends on NETFILTER_ADVANCED
select NETFILTER_XT_TARGET_CT
+config NETFILTER_XT_TARGET_FLOWOFFLOAD
+ tristate '"FLOWOFFLOAD" target support'
+ depends on NF_FLOW_TABLE
+ depends on NETFILTER_INGRESS
+ help
+ This option adds a `FLOWOFFLOAD' target, which uses the nf_flow_offload
+ module to speed up processing of packets by bypassing the usual
+ netfilter chains
+
config NETFILTER_XT_TARGET_RATEEST
tristate '"RATEEST" target support'
depends on NETFILTER_ADVANCED
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -134,6 +134,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIF
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o
obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_FLOWOFFLOAD) += xt_FLOWOFFLOAD.o
obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
obj-$(CONFIG_NETFILTER_XT_TARGET_HMARK) += xt_HMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
--- /dev/null
+++ b/net/netfilter/xt_FLOWOFFLOAD.c
@@ -0,0 +1,335 @@
+/*
+ * Copyright (C) 2018 Felix Fietkau <nbd@nbd.name>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/netfilter.h>
+#include <net/ip.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_flow_table.h>
+
+static struct nf_flowtable nf_flowtable;
+static HLIST_HEAD(hooks);
+static DEFINE_SPINLOCK(hooks_lock);
+static struct delayed_work hook_work;
+
+struct xt_flowoffload_hook {
+ struct hlist_node list;
+ struct nf_hook_ops ops;
+ bool registered;
+ bool used;
+};
+
+static unsigned int
+xt_flowoffload_net_hook(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ return nf_flow_offload_ip_hook(priv, skb, state);
+ case htons(ETH_P_IPV6):
+ return nf_flow_offload_ipv6_hook(priv, skb, state);
+ }
+
+ return NF_ACCEPT;
+}
+
+static int
+xt_flowoffload_create_hook(struct net_device *dev)
+{
+ struct xt_flowoffload_hook *hook;
+ struct nf_hook_ops *ops;
+
+ hook = kzalloc(sizeof(*hook), GFP_ATOMIC);
+ if (!hook)
+ return -ENOMEM;
+
+ ops = &hook->ops;
+ ops->pf = NFPROTO_NETDEV;
+ ops->hooknum = NF_NETDEV_INGRESS;
+ ops->priority = 10;
+ ops->priv = &nf_flowtable;
+ ops->hook = xt_flowoffload_net_hook;
+ ops->dev = dev;
+
+ hlist_add_head(&hook->list, &hooks);
+ mod_delayed_work(system_power_efficient_wq, &hook_work, 0);
+
+ return 0;
+}
+
+static struct xt_flowoffload_hook *
+flow_offload_lookup_hook(struct net_device *dev)
+{
+ struct xt_flowoffload_hook *hook;
+
+ hlist_for_each_entry(hook, &hooks, list) {
+ if (hook->ops.dev == dev)
+ return hook;
+ }
+
+ return NULL;
+}
+
+static void
+xt_flowoffload_check_device(struct net_device *dev)
+{
+ struct xt_flowoffload_hook *hook;
+
+ spin_lock_bh(&hooks_lock);
+ hook = flow_offload_lookup_hook(dev);
+ if (hook)
+ hook->used = true;
+ else
+ xt_flowoffload_create_hook(dev);
+ spin_unlock_bh(&hooks_lock);
+}
+
+static void
+xt_flowoffload_register_hooks(void)
+{
+ struct xt_flowoffload_hook *hook;
+
+restart:
+ hlist_for_each_entry(hook, &hooks, list) {
+ if (hook->registered)
+ continue;
+
+ hook->registered = true;
+ spin_unlock_bh(&hooks_lock);
+ nf_register_net_hook(dev_net(hook->ops.dev), &hook->ops);
+ spin_lock_bh(&hooks_lock);
+ goto restart;
+ }
+
+}
+
+static void
+xt_flowoffload_cleanup_hooks(void)
+{
+ struct xt_flowoffload_hook *hook;
+
+restart:
+ hlist_for_each_entry(hook, &hooks, list) {
+ if (hook->used)
+ continue;
+
+ hlist_del(&hook->list);
+ spin_unlock_bh(&hooks_lock);
+ nf_unregister_net_hook(dev_net(hook->ops.dev), &hook->ops);
+ kfree(hook);
+ spin_lock_bh(&hooks_lock);
+ goto restart;
+ }
+
+}
+
+static void
+xt_flowoffload_check_hook(struct flow_offload *flow, void *data)
+{
+ struct flow_offload_tuple *tuple = &flow->tuplehash[0].tuple;
+ struct xt_flowoffload_hook *hook;
+ bool *found = data;
+
+ spin_lock_bh(&hooks_lock);
+ hlist_for_each_entry(hook, &hooks, list) {
+ if (hook->ops.dev->ifindex != tuple->iifidx &&
+ hook->ops.dev->ifindex != tuple->oifidx)
+ continue;
+
+ hook->used = true;
+ *found = true;
+ }
+ spin_unlock_bh(&hooks_lock);
+}
+
+static void
+xt_flowoffload_hook_work(struct work_struct *work)
+{
+ struct xt_flowoffload_hook *hook;
+ bool found = false;
+ int err;
+
+ spin_lock_bh(&hooks_lock);
+ xt_flowoffload_register_hooks();
+ hlist_for_each_entry(hook, &hooks, list)
+ hook->used = false;
+ spin_unlock_bh(&hooks_lock);
+
+ err = nf_flow_table_iterate(&nf_flowtable, xt_flowoffload_check_hook,
+ &found);
+ if (err && err != -EAGAIN)
+ goto out;
+
+ spin_lock_bh(&hooks_lock);
+ xt_flowoffload_cleanup_hooks();
+ spin_unlock_bh(&hooks_lock);
+
+out:
+ if (found)
+ queue_delayed_work(system_power_efficient_wq, &hook_work, HZ);
+}
+
+static bool
+xt_flowoffload_skip(struct sk_buff *skb)
+{
+ struct ip_options *opt = &(IPCB(skb)->opt);
+
+ if (unlikely(opt->optlen))
+ return true;
+ if (skb_sec_path(skb))
+ return true;
+
+ return false;
+}
+
+static int
+xt_flowoffload_route(struct sk_buff *skb, const struct nf_conn *ct,
+ const struct xt_action_param *par,
+ struct nf_flow_route *route, enum ip_conntrack_dir dir)
+{
+ struct dst_entry *this_dst = skb_dst(skb);
+ struct dst_entry *other_dst = NULL;
+ struct flowi fl;
+
+ memset(&fl, 0, sizeof(fl));
+ switch (xt_family(par)) {
+ case NFPROTO_IPV4:
+ fl.u.ip4.daddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
+ break;
+ case NFPROTO_IPV6:
+ fl.u.ip6.daddr = ct->tuplehash[!dir].tuple.dst.u3.in6;
+ break;
+ }
+
+ nf_route(xt_net(par), &other_dst, &fl, false, xt_family(par));
+ if (!other_dst)
+ return -ENOENT;
+
+ route->tuple[dir].dst = this_dst;
+ route->tuple[dir].ifindex = xt_in(par)->ifindex;
+ route->tuple[!dir].dst = other_dst;
+ route->tuple[!dir].ifindex = xt_out(par)->ifindex;
+
+ return 0;
+}
+
+static unsigned int
+flowoffload_tg(struct sk_buff *skb, const struct xt_action_param *par)
+{
+ enum ip_conntrack_info ctinfo;
+ enum ip_conntrack_dir dir;
+ struct nf_flow_route route;
+ struct flow_offload *flow;
+ struct nf_conn *ct;
+
+ if (xt_flowoffload_skip(skb))
+ return XT_CONTINUE;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct == NULL)
+ return XT_CONTINUE;
+
+ switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
+ case IPPROTO_TCP:
+ case IPPROTO_UDP:
+ break;
+ default:
+ return XT_CONTINUE;
+ }
+
+ if (test_bit(IPS_HELPER_BIT, &ct->status))
+ return XT_CONTINUE;
+
+ if (ctinfo == IP_CT_NEW ||
+ ctinfo == IP_CT_RELATED)
+ return XT_CONTINUE;
+
+ if (!xt_in(par) || !xt_out(par))
+ return XT_CONTINUE;
+
+ if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
+ return XT_CONTINUE;
+
+ dir = CTINFO2DIR(ctinfo);
+
+ if (xt_flowoffload_route(skb, ct, par, &route, dir) < 0)
+ goto err_flow_route;
+
+ flow = flow_offload_alloc(ct, &route);
+ if (!flow)
+ goto err_flow_alloc;
+
+ if (flow_offload_add(&nf_flowtable, flow) < 0)
+ goto err_flow_add;
+
+ xt_flowoffload_check_device(xt_in(par));
+ xt_flowoffload_check_device(xt_out(par));
+
+ return XT_CONTINUE;
+
+err_flow_add:
+ flow_offload_free(flow);
+err_flow_alloc:
+ dst_release(route.tuple[!dir].dst);
+err_flow_route:
+ clear_bit(IPS_OFFLOAD_BIT, &ct->status);
+ return XT_CONTINUE;
+}
+
+
+static int flowoffload_chk(const struct xt_tgchk_param *par)
+{
+ return 0;
+}
+
+static struct xt_target offload_tg_reg __read_mostly = {
+ .family = NFPROTO_UNSPEC,
+ .name = "FLOWOFFLOAD",
+ .revision = 0,
+ .checkentry = flowoffload_chk,
+ .target = flowoffload_tg,
+ .me = THIS_MODULE,
+};
+
+static int xt_flowoffload_table_init(struct nf_flowtable *table)
+{
+ nf_flow_table_init(table);
+ return 0;
+}
+
+static void xt_flowoffload_table_cleanup(struct nf_flowtable *table)
+{
+ nf_flow_table_free(table);
+}
+
+static int __init xt_flowoffload_tg_init(void)
+{
+ int ret;
+
+ INIT_DELAYED_WORK(&hook_work, xt_flowoffload_hook_work);
+
+ ret = xt_flowoffload_table_init(&nf_flowtable);
+ if (ret)
+ return ret;
+
+ ret = xt_register_target(&offload_tg_reg);
+ if (ret)
+ xt_flowoffload_table_cleanup(&nf_flowtable);
+
+ return ret;
+}
+
+static void __exit xt_flowoffload_tg_exit(void)
+{
+ xt_unregister_target(&offload_tg_reg);
+ xt_flowoffload_table_cleanup(&nf_flowtable);
+}
+
+MODULE_LICENSE("GPL");
+module_init(xt_flowoffload_tg_init);
+module_exit(xt_flowoffload_tg_exit);
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -6,7 +6,6 @@
#include <linux/netdevice.h>
#include <net/ip.h>
#include <net/ip6_route.h>
-#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_flow_table.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
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