// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/workqueue.h>
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#include <linux/spinlock.h>
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#include <linux/netfilter/nf_conntrack_common.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/ip.h> /* for ipv4 options. */
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_extend.h>
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#include <net/netfilter/nf_flow_table.h>
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struct nft_flow_offload {
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struct nft_flowtable *flowtable;
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};
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static int nft_flow_route(const struct nft_pktinfo *pkt,
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const struct nf_conn *ct,
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struct nf_flow_route *route,
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enum ip_conntrack_dir dir)
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{
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struct dst_entry *this_dst = skb_dst(pkt->skb);
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struct dst_entry *other_dst = NULL;
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struct flowi fl;
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memset(&fl, 0, sizeof(fl));
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switch (nft_pf(pkt)) {
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case NFPROTO_IPV4:
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fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
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fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
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break;
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case NFPROTO_IPV6:
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fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
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fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
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break;
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}
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nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
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if (!other_dst)
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return -ENOENT;
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route->tuple[dir].dst = this_dst;
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route->tuple[!dir].dst = other_dst;
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return 0;
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}
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static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
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{
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if (skb_sec_path(skb))
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return true;
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if (family == NFPROTO_IPV4) {
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const struct ip_options *opt;
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opt = &(IPCB(skb)->opt);
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if (unlikely(opt->optlen))
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return true;
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}
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return false;
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}
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static void nft_flow_offload_eval(const struct nft_expr *expr,
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struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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struct nf_flowtable *flowtable = &priv->flowtable->data;
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struct tcphdr _tcph, *tcph = NULL;
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enum ip_conntrack_info ctinfo;
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struct nf_flow_route route;
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struct flow_offload *flow;
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enum ip_conntrack_dir dir;
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struct nf_conn *ct;
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int ret;
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if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
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goto out;
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ct = nf_ct_get(pkt->skb, &ctinfo);
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if (!ct)
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goto out;
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switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
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case IPPROTO_TCP:
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tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff,
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sizeof(_tcph), &_tcph);
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if (unlikely(!tcph || tcph->fin || tcph->rst))
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goto out;
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break;
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case IPPROTO_UDP:
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break;
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default:
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goto out;
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}
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if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
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ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
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goto out;
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if (!nf_ct_is_confirmed(ct))
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goto out;
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if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
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goto out;
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dir = CTINFO2DIR(ctinfo);
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if (nft_flow_route(pkt, ct, &route, dir) < 0)
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goto err_flow_route;
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flow = flow_offload_alloc(ct);
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if (!flow)
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goto err_flow_alloc;
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if (flow_offload_route_init(flow, &route) < 0)
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goto err_flow_add;
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if (tcph) {
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ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
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ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
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}
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ret = flow_offload_add(flowtable, flow);
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if (ret < 0)
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goto err_flow_add;
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dst_release(route.tuple[!dir].dst);
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return;
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err_flow_add:
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flow_offload_free(flow);
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err_flow_alloc:
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dst_release(route.tuple[!dir].dst);
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err_flow_route:
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clear_bit(IPS_OFFLOAD_BIT, &ct->status);
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out:
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regs->verdict.code = NFT_BREAK;
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}
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static int nft_flow_offload_validate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nft_data **data)
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{
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unsigned int hook_mask = (1 << NF_INET_FORWARD);
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return nft_chain_validate_hooks(ctx->chain, hook_mask);
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}
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static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
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[NFTA_FLOW_TABLE_NAME] = { .type = NLA_STRING,
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.len = NFT_NAME_MAXLEN - 1 },
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};
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static int nft_flow_offload_init(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nlattr * const tb[])
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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u8 genmask = nft_genmask_next(ctx->net);
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struct nft_flowtable *flowtable;
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if (!tb[NFTA_FLOW_TABLE_NAME])
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return -EINVAL;
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flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
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genmask);
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if (IS_ERR(flowtable))
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return PTR_ERR(flowtable);
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priv->flowtable = flowtable;
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flowtable->use++;
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return nf_ct_netns_get(ctx->net, ctx->family);
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}
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static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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enum nft_trans_phase phase)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
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}
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static void nft_flow_offload_activate(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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priv->flowtable->use++;
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}
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static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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nf_ct_netns_put(ctx->net, ctx->family);
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}
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static int nft_flow_offload_dump(struct sk_buff *skb, const struct nft_expr *expr)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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return -1;
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}
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static struct nft_expr_type nft_flow_offload_type;
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static const struct nft_expr_ops nft_flow_offload_ops = {
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.type = &nft_flow_offload_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
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.eval = nft_flow_offload_eval,
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.init = nft_flow_offload_init,
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.activate = nft_flow_offload_activate,
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.deactivate = nft_flow_offload_deactivate,
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.destroy = nft_flow_offload_destroy,
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.validate = nft_flow_offload_validate,
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.dump = nft_flow_offload_dump,
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};
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static struct nft_expr_type nft_flow_offload_type __read_mostly = {
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.name = "flow_offload",
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.ops = &nft_flow_offload_ops,
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.policy = nft_flow_offload_policy,
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.maxattr = NFTA_FLOW_MAX,
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.owner = THIS_MODULE,
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};
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static int flow_offload_netdev_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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if (event != NETDEV_DOWN)
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return NOTIFY_DONE;
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nf_flow_table_cleanup(dev);
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return NOTIFY_DONE;
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}
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static struct notifier_block flow_offload_netdev_notifier = {
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.notifier_call = flow_offload_netdev_event,
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};
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static int __init nft_flow_offload_module_init(void)
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{
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int err;
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err = register_netdevice_notifier(&flow_offload_netdev_notifier);
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if (err)
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goto err;
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err = nft_register_expr(&nft_flow_offload_type);
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if (err < 0)
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goto register_expr;
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return 0;
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register_expr:
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unregister_netdevice_notifier(&flow_offload_netdev_notifier);
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err:
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return err;
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}
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static void __exit nft_flow_offload_module_exit(void)
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{
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nft_unregister_expr(&nft_flow_offload_type);
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unregister_netdevice_notifier(&flow_offload_netdev_notifier);
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}
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module_init(nft_flow_offload_module_init);
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module_exit(nft_flow_offload_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_NFT_EXPR("flow_offload");
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MODULE_DESCRIPTION("nftables hardware flow offload module");
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