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Commit 09952107 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: flow table support for IPv6 



This patch adds the IPv6 flow table type, that implements the datapath
flow table to forward IPv6 traffic.

This patch exports ip6_dst_mtu_forward() that is required to check for
mtu to pass up packets that need PMTUD handling to the classic
forwarding path.

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 97add9f0

include/net/ipv6.h

+2 −0
Original line number Diff line number Diff line
@@ -969,6 +969,8 @@ static inline struct sk_buff *ip6_finish_skb(struct sock *sk) 
			      &inet6_sk(sk)->cork);

}



unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst);



int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,

		   struct flowi6 *fl6);

struct dst_entry *ip6_dst_lookup_flow(const struct sock *sk, struct flowi6 *fl6,

net/ipv6/ip6_output.c

+2 −1
Original line number Diff line number Diff line
@@ -378,7 +378,7 @@ static inline int ip6_forward_finish(struct net *net, struct sock *sk, 
	return dst_output(net, sk, skb);

}



static unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)

unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)

{

	unsigned int mtu;

	struct inet6_dev *idev;
@@ -398,6 +398,7 @@ static unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst) 


	return mtu;

}

EXPORT_SYMBOL_GPL(ip6_dst_mtu_forward);



static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)

{

net/ipv6/netfilter/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -71,6 +71,14 @@ config NFT_FIB_IPV6 
endif # NF_TABLES_IPV6

endif # NF_TABLES



config NF_FLOW_TABLE_IPV6

	select NF_FLOW_TABLE

	tristate "Netfilter flow table IPv6 module"

	help

	  This option adds the flow table IPv6 support.



	  To compile it as a module, choose M here.



config NF_DUP_IPV6

	tristate "Netfilter IPv6 packet duplication to alternate destination"

	depends on !NF_CONNTRACK || NF_CONNTRACK

net/ipv6/netfilter/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -45,6 +45,9 @@ obj-$(CONFIG_NFT_REDIR_IPV6) += nft_redir_ipv6.o 
obj-$(CONFIG_NFT_DUP_IPV6) += nft_dup_ipv6.o

obj-$(CONFIG_NFT_FIB_IPV6) += nft_fib_ipv6.o



# flow table support

obj-$(CONFIG_NF_FLOW_TABLE_IPV6) += nf_flow_table_ipv6.o



# matches

obj-$(CONFIG_IP6_NF_MATCH_AH) += ip6t_ah.o

obj-$(CONFIG_IP6_NF_MATCH_EUI64) += ip6t_eui64.o

net/ipv6/netfilter/nf_flow_table_ipv6.c

0 → 100644
+277 −0
Original line number Diff line number Diff line 
#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/netfilter.h>

#include <linux/rhashtable.h>

#include <linux/ipv6.h>

#include <linux/netdevice.h>

#include <linux/ipv6.h>

#include <net/ipv6.h>

#include <net/ip6_route.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_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;

}



/* 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_mtu(skb, mtu))

		return false;



	return true;

}



static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rt6_info *rt)

{

	u32 mtu;



	mtu = ip6_dst_mtu_forward(&rt->dst);

	if (__nf_flow_exceeds_mtu(skb, mtu))

		return true;



	return false;

}



static 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;



	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 = (struct rt6_info *)flow->tuplehash[dir].tuple.dst_cache;

	if (unlikely(nf_flow_exceeds_mtu(skb, rt)))

		return NF_ACCEPT;



	if (skb_try_make_writable(skb, sizeof(*ip6h)))

		return NF_DROP;



	if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&

	    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);

	neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);



	return NF_STOLEN;

}



static struct nf_flowtable_type flowtable_ipv6 = {

	.family		= NFPROTO_IPV6,

	.params		= &nf_flow_offload_rhash_params,

	.gc		= nf_flow_offload_work_gc,

	.hook		= nf_flow_offload_ipv6_hook,

	.owner		= THIS_MODULE,

};



static int __init nf_flow_ipv6_module_init(void)

{

	nft_register_flowtable_type(&flowtable_ipv6);



	return 0;

}



static void __exit nf_flow_ipv6_module_exit(void)

{

	nft_unregister_flowtable_type(&flowtable_ipv6);

}



module_init(nf_flow_ipv6_module_init);

module_exit(nf_flow_ipv6_module_exit);



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");

MODULE_ALIAS_NF_FLOWTABLE(AF_INET6);