forked from Minki/linux
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>
This commit is contained in:
Pablo Neira Ayuso
parent
ac2a66665e
commit
97add9f0d6
@ -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
|
||||
|
||||
@ -43,6 +43,9 @@ obj-$(CONFIG_NFT_REDIR_IPV4) += nft_redir_ipv4.o
|
||||
obj-$(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
|
||||
|
||||
|
||||
283
net/ipv4/netfilter/nf_flow_table_ipv4.c
Normal file
283
net/ipv4/netfilter/nf_flow_table_ipv4.c
Normal file
@ -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);
|
||||
Loading…
Reference in New Issue
Block a user