blob: 6452550d187fecd919c483cea627ed1adbf274cc [file] [log] [blame]
#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/ipv6.h>
#include <linux/netdevice.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/neighbour.h>
#include <net/netfilter/nf_flow_table.h>
/* For layer 4 checksum field offset. */
#include <linux/tcp.h>
#include <linux/udp.h>
static int nf_flow_state_check(struct flow_offload *flow, int proto,
struct sk_buff *skb, unsigned int thoff)
{
struct tcphdr *tcph;
if (proto != IPPROTO_TCP)
return 0;
if (!pskb_may_pull(skb, thoff + sizeof(*tcph)))
return -1;
tcph = (void *)(skb_network_header(skb) + thoff);
if (unlikely(tcph->fin || tcph->rst)) {
flow_offload_teardown(flow);
return -1;
}
return 0;
}
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;
}
csum_replace4(&iph->check, addr, new_addr);
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,
unsigned int thoff, enum flow_offload_tuple_dir dir)
{
struct iphdr *iph = ip_hdr(skb);
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 (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
return false;
return true;
}
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;
struct rtable *rt;
unsigned int thoff;
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;
dir = tuplehash->tuple.dir;
flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
rt = (struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
outdev = rt->dst.dev;
if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)) &&
(ip_hdr(skb)->frag_off & htons(IP_DF)) != 0)
return NF_ACCEPT;
if (skb_try_make_writable(skb, sizeof(*iph)))
return NF_DROP;
thoff = ip_hdr(skb)->ihl * 4;
if (nf_flow_state_check(flow, ip_hdr(skb)->protocol, skb, thoff))
return NF_ACCEPT;
if (nf_flow_nat_ip(flow, skb, thoff, 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);
skb_dst_set_noref(skb, &rt->dst);
neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);
return NF_STOLEN;
}
EXPORT_SYMBOL_GPL(nf_flow_offload_ip_hook);
static int nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
struct in6_addr *addr,
struct in6_addr *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_replace16(&tcph->check, skb, addr->s6_addr32,
new_addr->s6_addr32, true);
return 0;
}
static int nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
struct in6_addr *addr,
struct in6_addr *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_replace16(&udph->check, skb, addr->s6_addr32,
new_addr->s6_addr32, true);
if (!udph->check)
udph->check = CSUM_MANGLED_0;
}
return 0;
}
static int nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
unsigned int thoff, struct in6_addr *addr,
struct in6_addr *new_addr)
{
switch (ip6h->nexthdr) {
case IPPROTO_TCP:
if (nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr) < 0)
return NF_DROP;
break;
case IPPROTO_UDP:
if (nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr) < 0)
return NF_DROP;
break;
}
return 0;
}
static int nf_flow_snat_ipv6(const struct flow_offload *flow,
struct sk_buff *skb, struct ipv6hdr *ip6h,
unsigned int thoff,
enum flow_offload_tuple_dir dir)
{
struct in6_addr addr, new_addr;
switch (dir) {
case FLOW_OFFLOAD_DIR_ORIGINAL:
addr = ip6h->saddr;
new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
ip6h->saddr = new_addr;
break;
case FLOW_OFFLOAD_DIR_REPLY:
addr = ip6h->daddr;
new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
ip6h->daddr = new_addr;
break;
default:
return -1;
}
return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
}
static int nf_flow_dnat_ipv6(const struct flow_offload *flow,
struct sk_buff *skb, struct ipv6hdr *ip6h,
unsigned int thoff,
enum flow_offload_tuple_dir dir)
{
struct in6_addr addr, new_addr;
switch (dir) {
case FLOW_OFFLOAD_DIR_ORIGINAL:
addr = ip6h->daddr;
new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
ip6h->daddr = new_addr;
break;
case FLOW_OFFLOAD_DIR_REPLY:
addr = ip6h->saddr;
new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
ip6h->saddr = new_addr;
break;
default:
return -1;
}
return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
}
static int nf_flow_nat_ipv6(const struct flow_offload *flow,
struct sk_buff *skb,
enum flow_offload_tuple_dir dir)
{
struct ipv6hdr *ip6h = ipv6_hdr(skb);
unsigned int thoff = sizeof(*ip6h);
if (flow->flags & FLOW_OFFLOAD_SNAT &&
(nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
return -1;
if (flow->flags & FLOW_OFFLOAD_DNAT &&
(nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
return -1;
return 0;
}
static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
struct flow_offload_tuple *tuple)
{
struct flow_ports *ports;
struct ipv6hdr *ip6h;
unsigned int thoff;
if (!pskb_may_pull(skb, sizeof(*ip6h)))
return -1;
ip6h = ipv6_hdr(skb);
if (ip6h->nexthdr != IPPROTO_TCP &&
ip6h->nexthdr != IPPROTO_UDP)
return -1;
thoff = sizeof(*ip6h);
if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
return -1;
ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
tuple->src_v6 = ip6h->saddr;
tuple->dst_v6 = ip6h->daddr;
tuple->src_port = ports->source;
tuple->dst_port = ports->dest;
tuple->l3proto = AF_INET6;
tuple->l4proto = ip6h->nexthdr;
tuple->iifidx = dev->ifindex;
return 0;
}
unsigned int
nf_flow_offload_ipv6_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;
struct in6_addr *nexthop;
struct ipv6hdr *ip6h;
struct rt6_info *rt;
if (skb->protocol != htons(ETH_P_IPV6))
return NF_ACCEPT;
if (nf_flow_tuple_ipv6(skb, state->in, &tuple) < 0)
return NF_ACCEPT;
tuplehash = flow_offload_lookup(flow_table, &tuple);
if (tuplehash == NULL)
return NF_ACCEPT;
dir = tuplehash->tuple.dir;
flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
rt = (struct rt6_info *)flow->tuplehash[dir].tuple.dst_cache;
outdev = rt->dst.dev;
if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))
return NF_ACCEPT;
if (nf_flow_state_check(flow, ipv6_hdr(skb)->nexthdr, skb,
sizeof(*ip6h)))
return NF_ACCEPT;
if (skb_try_make_writable(skb, sizeof(*ip6h)))
return NF_DROP;
if (nf_flow_nat_ipv6(flow, skb, dir) < 0)
return NF_DROP;
flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
ip6h = ipv6_hdr(skb);
ip6h->hop_limit--;
skb->dev = outdev;
nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
skb_dst_set_noref(skb, &rt->dst);
neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
return NF_STOLEN;
}
EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);