279 lines
6.9 KiB
C
279 lines
6.9 KiB
C
#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/netfilter.h>
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#include <linux/rhashtable.h>
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#include <linux/ipv6.h>
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#include <linux/netdevice.h>
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#include <net/ipv6.h>
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#include <net/ip6_route.h>
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#include <net/neighbour.h>
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#include <net/netfilter/nf_flow_table.h>
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#include <net/netfilter/nf_tables.h>
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/* For layer 4 checksum field offset. */
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#include <linux/tcp.h>
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#include <linux/udp.h>
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static int nf_flow_nat_ipv6_tcp(struct sk_buff *skb, unsigned int thoff,
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struct in6_addr *addr,
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struct in6_addr *new_addr)
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{
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struct tcphdr *tcph;
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if (!pskb_may_pull(skb, thoff + sizeof(*tcph)) ||
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skb_try_make_writable(skb, thoff + sizeof(*tcph)))
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return -1;
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tcph = (void *)(skb_network_header(skb) + thoff);
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inet_proto_csum_replace16(&tcph->check, skb, addr->s6_addr32,
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new_addr->s6_addr32, true);
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return 0;
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}
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static int nf_flow_nat_ipv6_udp(struct sk_buff *skb, unsigned int thoff,
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struct in6_addr *addr,
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struct in6_addr *new_addr)
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{
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struct udphdr *udph;
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if (!pskb_may_pull(skb, thoff + sizeof(*udph)) ||
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skb_try_make_writable(skb, thoff + sizeof(*udph)))
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return -1;
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udph = (void *)(skb_network_header(skb) + thoff);
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if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
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inet_proto_csum_replace16(&udph->check, skb, addr->s6_addr32,
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new_addr->s6_addr32, true);
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if (!udph->check)
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udph->check = CSUM_MANGLED_0;
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}
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return 0;
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}
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static int nf_flow_nat_ipv6_l4proto(struct sk_buff *skb, struct ipv6hdr *ip6h,
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unsigned int thoff, struct in6_addr *addr,
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struct in6_addr *new_addr)
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{
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switch (ip6h->nexthdr) {
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case IPPROTO_TCP:
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if (nf_flow_nat_ipv6_tcp(skb, thoff, addr, new_addr) < 0)
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return NF_DROP;
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break;
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case IPPROTO_UDP:
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if (nf_flow_nat_ipv6_udp(skb, thoff, addr, new_addr) < 0)
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return NF_DROP;
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break;
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}
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return 0;
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}
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static int nf_flow_snat_ipv6(const struct flow_offload *flow,
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struct sk_buff *skb, struct ipv6hdr *ip6h,
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unsigned int thoff,
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enum flow_offload_tuple_dir dir)
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{
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struct in6_addr addr, new_addr;
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switch (dir) {
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case FLOW_OFFLOAD_DIR_ORIGINAL:
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addr = ip6h->saddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_v6;
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ip6h->saddr = new_addr;
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break;
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case FLOW_OFFLOAD_DIR_REPLY:
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addr = ip6h->daddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_v6;
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ip6h->daddr = new_addr;
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break;
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default:
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return -1;
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}
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return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
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}
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static int nf_flow_dnat_ipv6(const struct flow_offload *flow,
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struct sk_buff *skb, struct ipv6hdr *ip6h,
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unsigned int thoff,
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enum flow_offload_tuple_dir dir)
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{
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struct in6_addr addr, new_addr;
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switch (dir) {
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case FLOW_OFFLOAD_DIR_ORIGINAL:
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addr = ip6h->daddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_v6;
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ip6h->daddr = new_addr;
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break;
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case FLOW_OFFLOAD_DIR_REPLY:
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addr = ip6h->saddr;
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new_addr = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_v6;
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ip6h->saddr = new_addr;
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break;
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default:
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return -1;
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}
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return nf_flow_nat_ipv6_l4proto(skb, ip6h, thoff, &addr, &new_addr);
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}
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static int nf_flow_nat_ipv6(const struct flow_offload *flow,
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struct sk_buff *skb,
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enum flow_offload_tuple_dir dir)
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{
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struct ipv6hdr *ip6h = ipv6_hdr(skb);
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unsigned int thoff = sizeof(*ip6h);
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if (flow->flags & FLOW_OFFLOAD_SNAT &&
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(nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
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nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
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return -1;
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if (flow->flags & FLOW_OFFLOAD_DNAT &&
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(nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
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nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
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return -1;
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return 0;
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}
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static int nf_flow_tuple_ipv6(struct sk_buff *skb, const struct net_device *dev,
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struct flow_offload_tuple *tuple)
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{
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struct flow_ports *ports;
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struct ipv6hdr *ip6h;
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unsigned int thoff;
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if (!pskb_may_pull(skb, sizeof(*ip6h)))
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return -1;
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ip6h = ipv6_hdr(skb);
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if (ip6h->nexthdr != IPPROTO_TCP &&
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ip6h->nexthdr != IPPROTO_UDP)
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return -1;
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thoff = sizeof(*ip6h);
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if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
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return -1;
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ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
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tuple->src_v6 = ip6h->saddr;
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tuple->dst_v6 = ip6h->daddr;
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tuple->src_port = ports->source;
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tuple->dst_port = ports->dest;
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tuple->l3proto = AF_INET6;
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tuple->l4proto = ip6h->nexthdr;
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tuple->iifidx = dev->ifindex;
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return 0;
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}
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/* Based on ip_exceeds_mtu(). */
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static bool __nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
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{
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if (skb->len <= mtu)
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return false;
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if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
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return false;
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return true;
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}
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static bool nf_flow_exceeds_mtu(struct sk_buff *skb, const struct rt6_info *rt)
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{
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u32 mtu;
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mtu = ip6_dst_mtu_forward(&rt->dst);
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if (__nf_flow_exceeds_mtu(skb, mtu))
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return true;
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return false;
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}
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unsigned int
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nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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struct flow_offload_tuple_rhash *tuplehash;
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struct nf_flowtable *flow_table = priv;
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struct flow_offload_tuple tuple = {};
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enum flow_offload_tuple_dir dir;
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struct flow_offload *flow;
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struct net_device *outdev;
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struct in6_addr *nexthop;
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struct ipv6hdr *ip6h;
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struct rt6_info *rt;
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if (skb->protocol != htons(ETH_P_IPV6))
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return NF_ACCEPT;
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if (nf_flow_tuple_ipv6(skb, state->in, &tuple) < 0)
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return NF_ACCEPT;
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tuplehash = flow_offload_lookup(flow_table, &tuple);
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if (tuplehash == NULL)
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return NF_ACCEPT;
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outdev = dev_get_by_index_rcu(state->net, tuplehash->tuple.oifidx);
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if (!outdev)
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return NF_ACCEPT;
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dir = tuplehash->tuple.dir;
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flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
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rt = (struct rt6_info *)flow->tuplehash[dir].tuple.dst_cache;
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if (unlikely(nf_flow_exceeds_mtu(skb, rt)))
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return NF_ACCEPT;
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if (skb_try_make_writable(skb, sizeof(*ip6h)))
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return NF_DROP;
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if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&
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nf_flow_nat_ipv6(flow, skb, dir) < 0)
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return NF_DROP;
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flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
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ip6h = ipv6_hdr(skb);
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ip6h->hop_limit--;
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skb->dev = outdev;
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nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
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neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);
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return NF_STOLEN;
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}
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EXPORT_SYMBOL_GPL(nf_flow_offload_ipv6_hook);
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static struct nf_flowtable_type flowtable_ipv6 = {
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.family = NFPROTO_IPV6,
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.params = &nf_flow_offload_rhash_params,
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.gc = nf_flow_offload_work_gc,
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.free = nf_flow_table_free,
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.hook = nf_flow_offload_ipv6_hook,
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.owner = THIS_MODULE,
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};
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static int __init nf_flow_ipv6_module_init(void)
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{
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nft_register_flowtable_type(&flowtable_ipv6);
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return 0;
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}
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static void __exit nf_flow_ipv6_module_exit(void)
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{
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nft_unregister_flowtable_type(&flowtable_ipv6);
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}
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module_init(nf_flow_ipv6_module_init);
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module_exit(nf_flow_ipv6_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
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MODULE_ALIAS_NF_FLOWTABLE(AF_INET6);
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