--- /dev/null
+From: Pablo Neira Ayuso <pablo@netfilter.org>
+Date: Sun, 7 Jan 2018 01:04:15 +0100
+Subject: [PATCH] netfilter: flow table support for IPv4
+
+This patch adds the IPv4 flow table type, that implements the datapath
+flow table to forward IPv4 traffic. Rationale is:
+
+1) Look up for the packet in the flow table, from the ingress hook.
+2) If there's a hit, decrement ttl and pass it on to the neighbour layer
+ for transmission.
+3) If there's a miss, packet is passed up to the classic forwarding
+ path.
+
+This patch also supports layer 3 source and destination NAT.
+
+Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
+---
+ create mode 100644 net/ipv4/netfilter/nf_flow_table_ipv4.c
+
+--- a/net/ipv4/netfilter/Kconfig
++++ b/net/ipv4/netfilter/Kconfig
+@@ -78,6 +78,14 @@ config NF_TABLES_ARP
+
+ endif # NF_TABLES
+
++config NF_FLOW_TABLE_IPV4
++ select NF_FLOW_TABLE
++ tristate "Netfilter flow table IPv4 module"
++ help
++ This option adds the flow table IPv4 support.
++
++ To compile it as a module, choose M here.
++
+ config NF_DUP_IPV4
+ tristate "Netfilter IPv4 packet duplication to alternate destination"
+ depends on !NF_CONNTRACK || NF_CONNTRACK
+--- a/net/ipv4/netfilter/Makefile
++++ b/net/ipv4/netfilter/Makefile
+@@ -43,6 +43,9 @@ obj-$(CONFIG_NFT_REDIR_IPV4) += nft_redi
+ obj-$(CONFIG_NFT_DUP_IPV4) += nft_dup_ipv4.o
+ obj-$(CONFIG_NF_TABLES_ARP) += nf_tables_arp.o
+
++# flow table support
++obj-$(CONFIG_NF_FLOW_TABLE_IPV4) += nf_flow_table_ipv4.o
++
+ # generic IP tables
+ obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o
+
+--- /dev/null
++++ b/net/ipv4/netfilter/nf_flow_table_ipv4.c
+@@ -0,0 +1,283 @@
++#include <linux/kernel.h>
++#include <linux/init.h>
++#include <linux/module.h>
++#include <linux/netfilter.h>
++#include <linux/rhashtable.h>
++#include <linux/ip.h>
++#include <linux/netdevice.h>
++#include <net/ip.h>
++#include <net/neighbour.h>
++#include <net/netfilter/nf_flow_table.h>
++#include <net/netfilter/nf_tables.h>
++/* For layer 4 checksum field offset. */
++#include <linux/tcp.h>
++#include <linux/udp.h>
++
++static int nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,
++ __be32 addr, __be32 new_addr)
++{
++ struct tcphdr *tcph;
++
++ if (!pskb_may_pull(skb, thoff + sizeof(*tcph)) ||
++ skb_try_make_writable(skb, thoff + sizeof(*tcph)))
++ return -1;
++
++ tcph = (void *)(skb_network_header(skb) + thoff);
++ inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, true);
++
++ return 0;
++}
++
++static int nf_flow_nat_ip_udp(struct sk_buff *skb, unsigned int thoff,
++ __be32 addr, __be32 new_addr)
++{
++ struct udphdr *udph;
++
++ if (!pskb_may_pull(skb, thoff + sizeof(*udph)) ||
++ skb_try_make_writable(skb, thoff + sizeof(*udph)))
++ return -1;
++
++ udph = (void *)(skb_network_header(skb) + thoff);
++ if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
++ inet_proto_csum_replace4(&udph->check, skb, addr,
++ new_addr, true);
++ if (!udph->check)
++ udph->check = CSUM_MANGLED_0;
++ }
++
++ return 0;
++}
++
++static int nf_flow_nat_ip_l4proto(struct sk_buff *skb, struct iphdr *iph,
++ unsigned int thoff, __be32 addr,
++ __be32 new_addr)
++{
++ switch (iph->protocol) {
++ case IPPROTO_TCP:
++ if (nf_flow_nat_ip_tcp(skb, thoff, addr, new_addr) < 0)
++ return NF_DROP;
++ break;
++ case IPPROTO_UDP:
++ if (nf_flow_nat_ip_udp(skb, thoff, addr, new_addr) < 0)
++ return NF_DROP;
++ break;
++ }
++
++ return 0;
++}
++
++static int nf_flow_snat_ip(const struct flow_offload *flow, struct sk_buff *skb,
++ struct iphdr *iph, unsigned int thoff,
++ enum flow_offload_tuple_dir dir)
++{
++ __be32 addr, new_addr;
++
++ switch (dir) {
++ case FLOW_OFFLOAD_DIR_ORIGINAL:
++ addr = iph->saddr;
++ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v4.s_addr;
++ iph->saddr = new_addr;
++ break;
++ case FLOW_OFFLOAD_DIR_REPLY:
++ addr = iph->daddr;
++ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v4.s_addr;
++ iph->daddr = new_addr;
++ break;
++ default:
++ return -1;
++ }
++ csum_replace4(&iph->check, addr, new_addr);
++
++ return nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
++}
++
++static int nf_flow_dnat_ip(const struct flow_offload *flow, struct sk_buff *skb,
++ struct iphdr *iph, unsigned int thoff,
++ enum flow_offload_tuple_dir dir)
++{
++ __be32 addr, new_addr;
++
++ switch (dir) {
++ case FLOW_OFFLOAD_DIR_ORIGINAL:
++ addr = iph->daddr;
++ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v4.s_addr;
++ iph->daddr = new_addr;
++ break;
++ case FLOW_OFFLOAD_DIR_REPLY:
++ addr = iph->saddr;
++ new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v4.s_addr;
++ iph->saddr = new_addr;
++ break;
++ default:
++ return -1;
++ }
++
++ return nf_flow_nat_ip_l4proto(skb, iph, thoff, addr, new_addr);
++}
++
++static int nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
++ enum flow_offload_tuple_dir dir)
++{
++ struct iphdr *iph = ip_hdr(skb);
++ unsigned int thoff = iph->ihl * 4;
++
++ if (flow->flags & FLOW_OFFLOAD_SNAT &&
++ (nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
++ nf_flow_snat_ip(flow, skb, iph, thoff, dir) < 0))
++ return -1;
++ if (flow->flags & FLOW_OFFLOAD_DNAT &&
++ (nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
++ nf_flow_dnat_ip(flow, skb, iph, thoff, dir) < 0))
++ return -1;
++
++ return 0;
++}
++
++static bool ip_has_options(unsigned int thoff)
++{
++ return thoff != sizeof(struct iphdr);
++}
++
++static int nf_flow_tuple_ip(struct sk_buff *skb, const struct net_device *dev,
++ struct flow_offload_tuple *tuple)
++{
++ struct flow_ports *ports;
++ unsigned int thoff;
++ struct iphdr *iph;
++
++ if (!pskb_may_pull(skb, sizeof(*iph)))
++ return -1;
++
++ iph = ip_hdr(skb);
++ thoff = iph->ihl * 4;
++
++ if (ip_is_fragment(iph) ||
++ unlikely(ip_has_options(thoff)))
++ return -1;
++
++ if (iph->protocol != IPPROTO_TCP &&
++ iph->protocol != IPPROTO_UDP)
++ return -1;
++
++ thoff = iph->ihl * 4;
++ if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
++ return -1;
++
++ ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
++
++ tuple->src_v4.s_addr = iph->saddr;
++ tuple->dst_v4.s_addr = iph->daddr;
++ tuple->src_port = ports->source;
++ tuple->dst_port = ports->dest;
++ tuple->l3proto = AF_INET;
++ tuple->l4proto = iph->protocol;
++ tuple->iifidx = dev->ifindex;
++
++ return 0;
++}
++
++/* Based on ip_exceeds_mtu(). */
++static bool __nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
++{
++ if (skb->len <= mtu)
++ return false;
++
++ if ((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0)
++ return false;
++
++ if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
++ return false;
++
++ return true;
++}
++
++static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rtable *rt)
++{
++ u32 mtu;
++
++ mtu = ip_dst_mtu_maybe_forward(&rt->dst, true);
++ if (__nf_flow_exceeds_mtu(skb, mtu))
++ return true;
++
++ return false;
++}
++
++static unsigned int
++nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
++ const struct nf_hook_state *state)
++{
++ struct flow_offload_tuple_rhash *tuplehash;
++ struct nf_flowtable *flow_table = priv;
++ struct flow_offload_tuple tuple = {};
++ enum flow_offload_tuple_dir dir;
++ struct flow_offload *flow;
++ struct net_device *outdev;
++ const struct rtable *rt;
++ struct iphdr *iph;
++ __be32 nexthop;
++
++ if (skb->protocol != htons(ETH_P_IP))
++ return NF_ACCEPT;
++
++ if (nf_flow_tuple_ip(skb, state->in, &tuple) < 0)
++ return NF_ACCEPT;
++
++ tuplehash = flow_offload_lookup(flow_table, &tuple);
++ if (tuplehash == NULL)
++ return NF_ACCEPT;
++
++ outdev = dev_get_by_index_rcu(state->net, tuplehash->tuple.oifidx);
++ if (!outdev)
++ return NF_ACCEPT;
++
++ dir = tuplehash->tuple.dir;
++ flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
++
++ rt = (const struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
++ if (unlikely(nf_flow_exceeds_mtu(skb, rt)))
++ return NF_ACCEPT;
++
++ if (skb_try_make_writable(skb, sizeof(*iph)))
++ return NF_DROP;
++
++ if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&
++ nf_flow_nat_ip(flow, skb, dir) < 0)
++ return NF_DROP;
++
++ flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
++ iph = ip_hdr(skb);
++ ip_decrease_ttl(iph);
++
++ skb->dev = outdev;
++ nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
++ neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
++
++ return NF_STOLEN;
++}
++
++static struct nf_flowtable_type flowtable_ipv4 = {
++ .family = NFPROTO_IPV4,
++ .params = &nf_flow_offload_rhash_params,
++ .gc = nf_flow_offload_work_gc,
++ .hook = nf_flow_offload_ip_hook,
++ .owner = THIS_MODULE,
++};
++
++static int __init nf_flow_ipv4_module_init(void)
++{
++ nft_register_flowtable_type(&flowtable_ipv4);
++
++ return 0;
++}
++
++static void __exit nf_flow_ipv4_module_exit(void)
++{
++ nft_unregister_flowtable_type(&flowtable_ipv4);
++}
++
++module_init(nf_flow_ipv4_module_init);
++module_exit(nf_flow_ipv4_module_exit);
++
++MODULE_LICENSE("GPL");
++MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
++MODULE_ALIAS_NF_FLOWTABLE(AF_INET);
projects / openwrt / staging / chunkeey.git / blobdiff