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- From: Pablo Neira Ayuso <pablo@netfilter.org>
- Date: Sun, 7 Jan 2018 01:04:19 +0100
- Subject: [PATCH] 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: Pablo Neira Ayuso <pablo@netfilter.org>
- ---
- create mode 100644 net/ipv6/netfilter/nf_flow_table_ipv6.c
- --- a/include/net/ipv6.h
- +++ b/include/net/ipv6.h
- @@ -860,6 +860,8 @@ static inline struct sk_buff *ip6_finish
- &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(struct net *net, const struct sock *sk, struct flowi6 *fl6,
- --- a/net/ipv6/ip6_output.c
- +++ b/net/ipv6/ip6_output.c
- @@ -381,7 +381,7 @@ static inline int ip6_forward_finish(str
- 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;
- @@ -401,6 +401,7 @@ static unsigned int ip6_dst_mtu_forward(
-
- return mtu;
- }
- +EXPORT_SYMBOL_GPL(ip6_dst_mtu_forward);
-
- static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
- {
- --- a/net/ipv6/netfilter/Kconfig
- +++ b/net/ipv6/netfilter/Kconfig
- @@ -99,6 +99,14 @@ 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
- --- a/net/ipv6/netfilter/Makefile
- +++ b/net/ipv6/netfilter/Makefile
- @@ -45,6 +45,9 @@ obj-$(CONFIG_NFT_REDIR_IPV6) += nft_redi
- obj-$(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
- --- /dev/null
- +++ b/net/ipv6/netfilter/nf_flow_table_ipv6.c
- @@ -0,0 +1,277 @@
- +#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);
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