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nft_flow_offload.c (5880B)


      1 #include <linux/kernel.h>
      2 #include <linux/module.h>
      3 #include <linux/init.h>
      4 #include <linux/netlink.h>
      5 #include <linux/netfilter.h>
      6 #include <linux/workqueue.h>
      7 #include <linux/spinlock.h>
      8 #include <linux/netfilter/nf_tables.h>
      9 #include <net/ip.h> /* for ipv4 options. */
     10 #include <net/netfilter/nf_tables.h>
     11 #include <net/netfilter/nf_tables_core.h>
     12 #include <net/netfilter/nf_conntrack_core.h>
     13 #include <linux/netfilter/nf_conntrack_common.h>
     14 #include <net/netfilter/nf_flow_table.h>
     15 #include <net/netfilter/nf_conntrack_helper.h>
     16 
     17 struct nft_flow_offload {
     18 	struct nft_flowtable	*flowtable;
     19 };
     20 
     21 static int nft_flow_route(const struct nft_pktinfo *pkt,
     22 			  const struct nf_conn *ct,
     23 			  struct nf_flow_route *route,
     24 			  enum ip_conntrack_dir dir)
     25 {
     26 	struct dst_entry *this_dst = skb_dst(pkt->skb);
     27 	struct dst_entry *other_dst = NULL;
     28 	struct flowi fl;
     29 
     30 	memset(&fl, 0, sizeof(fl));
     31 	switch (nft_pf(pkt)) {
     32 	case NFPROTO_IPV4:
     33 		fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
     34 		fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
     35 		break;
     36 	case NFPROTO_IPV6:
     37 		fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
     38 		fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
     39 		break;
     40 	}
     41 
     42 	nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
     43 	if (!other_dst)
     44 		return -ENOENT;
     45 
     46 	route->tuple[dir].dst		= this_dst;
     47 	route->tuple[!dir].dst		= other_dst;
     48 
     49 	return 0;
     50 }
     51 
     52 static bool nft_flow_offload_skip(struct sk_buff *skb)
     53 {
     54 	struct ip_options *opt  = &(IPCB(skb)->opt);
     55 
     56 	if (unlikely(opt->optlen))
     57 		return true;
     58 	if (skb_sec_path(skb))
     59 		return true;
     60 
     61 	return false;
     62 }
     63 
     64 static void nft_flow_offload_eval(const struct nft_expr *expr,
     65 				  struct nft_regs *regs,
     66 				  const struct nft_pktinfo *pkt)
     67 {
     68 	struct nft_flow_offload *priv = nft_expr_priv(expr);
     69 	struct nf_flowtable *flowtable = &priv->flowtable->data;
     70 	const struct nf_conn_help *help;
     71 	enum ip_conntrack_info ctinfo;
     72 	struct nf_flow_route route;
     73 	struct flow_offload *flow;
     74 	enum ip_conntrack_dir dir;
     75 	struct nf_conn *ct;
     76 	int ret;
     77 
     78 	if (nft_flow_offload_skip(pkt->skb))
     79 		goto out;
     80 
     81 	ct = nf_ct_get(pkt->skb, &ctinfo);
     82 	if (!ct)
     83 		goto out;
     84 
     85 	switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
     86 	case IPPROTO_TCP:
     87 	case IPPROTO_UDP:
     88 		break;
     89 	default:
     90 		goto out;
     91 	}
     92 
     93 	help = nfct_help(ct);
     94 	if (help)
     95 		goto out;
     96 
     97 	if (ctinfo == IP_CT_NEW ||
     98 	    ctinfo == IP_CT_RELATED)
     99 		goto out;
    100 
    101 	if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
    102 		goto out;
    103 
    104 	dir = CTINFO2DIR(ctinfo);
    105 	if (nft_flow_route(pkt, ct, &route, dir) < 0)
    106 		goto err_flow_route;
    107 
    108 	flow = flow_offload_alloc(ct, &route);
    109 	if (!flow)
    110 		goto err_flow_alloc;
    111 
    112 	ret = flow_offload_add(flowtable, flow);
    113 	if (ret < 0)
    114 		goto err_flow_add;
    115 
    116 	return;
    117 
    118 err_flow_add:
    119 	flow_offload_free(flow);
    120 err_flow_alloc:
    121 	dst_release(route.tuple[!dir].dst);
    122 err_flow_route:
    123 	clear_bit(IPS_OFFLOAD_BIT, &ct->status);
    124 out:
    125 	regs->verdict.code = NFT_BREAK;
    126 }
    127 
    128 static int nft_flow_offload_validate(const struct nft_ctx *ctx,
    129 				     const struct nft_expr *expr,
    130 				     const struct nft_data **data)
    131 {
    132 	unsigned int hook_mask = (1 << NF_INET_FORWARD);
    133 
    134 	return nft_chain_validate_hooks(ctx->chain, hook_mask);
    135 }
    136 
    137 static int nft_flow_offload_init(const struct nft_ctx *ctx,
    138 				 const struct nft_expr *expr,
    139 				 const struct nlattr * const tb[])
    140 {
    141 	struct nft_flow_offload *priv = nft_expr_priv(expr);
    142 	u8 genmask = nft_genmask_next(ctx->net);
    143 	struct nft_flowtable *flowtable;
    144 
    145 	if (!tb[NFTA_FLOW_TABLE_NAME])
    146 		return -EINVAL;
    147 
    148 	flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
    149 					 genmask);
    150 	if (IS_ERR(flowtable))
    151 		return PTR_ERR(flowtable);
    152 
    153 	priv->flowtable = flowtable;
    154 	flowtable->use++;
    155 
    156 	return nf_ct_netns_get(ctx->net, ctx->family);
    157 }
    158 
    159 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
    160 				     const struct nft_expr *expr)
    161 {
    162 	struct nft_flow_offload *priv = nft_expr_priv(expr);
    163 
    164 	priv->flowtable->use--;
    165 	nf_ct_netns_put(ctx->net, ctx->family);
    166 }
    167 
    168 static int nft_flow_offload_dump(struct sk_buff *skb, const struct nft_expr *expr)
    169 {
    170 	struct nft_flow_offload *priv = nft_expr_priv(expr);
    171 
    172 	if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
    173 		goto nla_put_failure;
    174 
    175 	return 0;
    176 
    177 nla_put_failure:
    178 	return -1;
    179 }
    180 
    181 static struct nft_expr_type nft_flow_offload_type;
    182 static const struct nft_expr_ops nft_flow_offload_ops = {
    183 	.type		= &nft_flow_offload_type,
    184 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
    185 	.eval		= nft_flow_offload_eval,
    186 	.init		= nft_flow_offload_init,
    187 	.destroy	= nft_flow_offload_destroy,
    188 	.validate	= nft_flow_offload_validate,
    189 	.dump		= nft_flow_offload_dump,
    190 };
    191 
    192 static struct nft_expr_type nft_flow_offload_type __read_mostly = {
    193 	.name		= "flow_offload",
    194 	.ops		= &nft_flow_offload_ops,
    195 	.maxattr	= NFTA_FLOW_MAX,
    196 	.owner		= THIS_MODULE,
    197 };
    198 
    199 static int flow_offload_netdev_event(struct notifier_block *this,
    200 				     unsigned long event, void *ptr)
    201 {
    202 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
    203 
    204 	if (event != NETDEV_DOWN)
    205 		return NOTIFY_DONE;
    206 
    207 	nf_flow_table_cleanup(dev);
    208 
    209 	return NOTIFY_DONE;
    210 }
    211 
    212 static struct notifier_block flow_offload_netdev_notifier = {
    213 	.notifier_call	= flow_offload_netdev_event,
    214 };
    215 
    216 static int __init nft_flow_offload_module_init(void)
    217 {
    218 	int err;
    219 
    220 	err = register_netdevice_notifier(&flow_offload_netdev_notifier);
    221 	if (err)
    222 		goto err;
    223 
    224 	err = nft_register_expr(&nft_flow_offload_type);
    225 	if (err < 0)
    226 		goto register_expr;
    227 
    228 	return 0;
    229 
    230 register_expr:
    231 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
    232 err:
    233 	return err;
    234 }
    235 
    236 static void __exit nft_flow_offload_module_exit(void)
    237 {
    238 	nft_unregister_expr(&nft_flow_offload_type);
    239 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
    240 }
    241 
    242 module_init(nft_flow_offload_module_init);
    243 module_exit(nft_flow_offload_module_exit);
    244 
    245 MODULE_LICENSE("GPL");
    246 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
    247 MODULE_ALIAS_NFT_EXPR("flow_offload");