net/netfilter/nft_flow_offload.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/module.h>
   4 #include <linux/init.h>
   5 #include <linux/netlink.h>
   6 #include <linux/netfilter.h>
   7 #include <linux/workqueue.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/netfilter/nf_conntrack_common.h>
  10 #include <linux/netfilter/nf_tables.h>
  11 #include <net/ip.h> /* for ipv4 options. */
  12 #include <net/netfilter/nf_tables.h>
  13 #include <net/netfilter/nf_tables_core.h>
  14 #include <net/netfilter/nf_conntrack_core.h>
  15 #include <net/netfilter/nf_conntrack_extend.h>
  16 #include <net/netfilter/nf_flow_table.h>
  17
  18 struct nft_flow_offload {
  19         struct nft_flowtable    *flowtable;
  20 };
  21
  22 static enum flow_offload_xmit_type nft_xmit_type(struct dst_entry *dst)
  23 {
  24         if (dst_xfrm(dst))
  25                 return FLOW_OFFLOAD_XMIT_XFRM;
  26
  27         return FLOW_OFFLOAD_XMIT_NEIGH;
  28 }
  29
  30 static void nft_default_forward_path(struct nf_flow_route *route,
  31                                      struct dst_entry *dst_cache,
  32                                      enum ip_conntrack_dir dir)
  33 {
  34         route->tuple[!dir].in.ifindex   = dst_cache->dev->ifindex;
  35         route->tuple[dir].dst           = dst_cache;
  36         route->tuple[dir].xmit_type     = nft_xmit_type(dst_cache);
  37 }
  38
  39 static int nft_dev_fill_forward_path(const struct nf_flow_route *route,
  40                                      const struct dst_entry *dst_cache,
  41                                      const struct nf_conn *ct,
  42                                      enum ip_conntrack_dir dir, u8 *ha,
  43                                      struct net_device_path_stack *stack)
  44 {
  45         const void *daddr = &ct->tuplehash[!dir].tuple.src.u3;
  46         struct net_device *dev = dst_cache->dev;
  47         struct neighbour *n;
  48         u8 nud_state;
  49
  50         n = dst_neigh_lookup(dst_cache, daddr);
  51         if (!n)
  52                 return -1;
  53
  54         read_lock_bh(&n->lock);
  55         nud_state = n->nud_state;
  56         ether_addr_copy(ha, n->ha);
  57         read_unlock_bh(&n->lock);
  58         neigh_release(n);
  59
  60         if (!(nud_state & NUD_VALID))
  61                 return -1;
  62
  63         return dev_fill_forward_path(dev, ha, stack);
  64 }
  65
  66 struct nft_forward_info {
  67         const struct net_device *indev;
  68         const struct net_device *outdev;
  69         struct id {
  70                 __u16   id;
  71                 __be16  proto;
  72         } encap[NF_FLOW_TABLE_ENCAP_MAX];
  73         u8 num_encaps;
  74         u8 h_source[ETH_ALEN];
  75         u8 h_dest[ETH_ALEN];
  76         enum flow_offload_xmit_type xmit_type;
  77 };
  78
  79 static void nft_dev_path_info(const struct net_device_path_stack *stack,
  80                               struct nft_forward_info *info,
  81                               unsigned char *ha)
  82 {
  83         const struct net_device_path *path;
  84         int i;
  85
  86         memcpy(info->h_dest, ha, ETH_ALEN);
  87
  88         for (i = 0; i < stack->num_paths; i++) {
  89                 path = &stack->path[i];
  90                 switch (path->type) {
  91                 case DEV_PATH_ETHERNET:
  92                 case DEV_PATH_VLAN:
  93                         info->indev = path->dev;
  94                         if (is_zero_ether_addr(info->h_source))
  95                                 memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
  96
  97                         if (path->type == DEV_PATH_ETHERNET)
  98                                 break;
  99
 100                         /* DEV_PATH_VLAN */
 101                         if (info->num_encaps >= NF_FLOW_TABLE_ENCAP_MAX) {
 102                                 info->indev = NULL;
 103                                 break;
 104                         }
 105                         info->outdev = path->dev;
 106                         info->encap[info->num_encaps].id = path->encap.id;
 107                         info->encap[info->num_encaps].proto = path->encap.proto;
 108                         info->num_encaps++;
 109                         break;
 110                 case DEV_PATH_BRIDGE:
 111                         if (is_zero_ether_addr(info->h_source))
 112                                 memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
 113
 114                         info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
 115                         break;
 116                 default:
 117                         info->indev = NULL;
 118                         break;
 119                 }
 120         }
 121         if (!info->outdev)
 122                 info->outdev = info->indev;
 123 }
 124
 125 static bool nft_flowtable_find_dev(const struct net_device *dev,
 126                                    struct nft_flowtable *ft)
 127 {
 128         struct nft_hook *hook;
 129         bool found = false;
 130
 131         list_for_each_entry_rcu(hook, &ft->hook_list, list) {
 132                 if (hook->ops.dev != dev)
 133                         continue;
 134
 135                 found = true;
 136                 break;
 137         }
 138
 139         return found;
 140 }
 141
 142 static void nft_dev_forward_path(struct nf_flow_route *route,
 143                                  const struct nf_conn *ct,
 144                                  enum ip_conntrack_dir dir,
 145                                  struct nft_flowtable *ft)
 146 {
 147         const struct dst_entry *dst = route->tuple[dir].dst;
 148         struct net_device_path_stack stack;
 149         struct nft_forward_info info = {};
 150         unsigned char ha[ETH_ALEN];
 151         int i;
 152
 153         if (nft_dev_fill_forward_path(route, dst, ct, dir, ha, &stack) >= 0)
 154                 nft_dev_path_info(&stack, &info, ha);
 155
 156         if (!info.indev || !nft_flowtable_find_dev(info.indev, ft))
 157                 return;
 158
 159         route->tuple[!dir].in.ifindex = info.indev->ifindex;
 160         for (i = 0; i < info.num_encaps; i++) {
 161                 route->tuple[!dir].in.encap[i].id = info.encap[i].id;
 162                 route->tuple[!dir].in.encap[i].proto = info.encap[i].proto;
 163         }
 164         route->tuple[!dir].in.num_encaps = info.num_encaps;
 165
 166         if (info.xmit_type == FLOW_OFFLOAD_XMIT_DIRECT) {
 167                 memcpy(route->tuple[dir].out.h_source, info.h_source, ETH_ALEN);
 168                 memcpy(route->tuple[dir].out.h_dest, info.h_dest, ETH_ALEN);
 169                 route->tuple[dir].out.ifindex = info.outdev->ifindex;
 170                 route->tuple[dir].xmit_type = info.xmit_type;
 171         }
 172 }
 173
 174 static int nft_flow_route(const struct nft_pktinfo *pkt,
 175                           const struct nf_conn *ct,
 176                           struct nf_flow_route *route,
 177                           enum ip_conntrack_dir dir,
 178                           struct nft_flowtable *ft)
 179 {
 180         struct dst_entry *this_dst = skb_dst(pkt->skb);
 181         struct dst_entry *other_dst = NULL;
 182         struct flowi fl;
 183
 184         memset(&fl, 0, sizeof(fl));
 185         switch (nft_pf(pkt)) {
 186         case NFPROTO_IPV4:
 187                 fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
 188                 fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
 189                 break;
 190         case NFPROTO_IPV6:
 191                 fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
 192                 fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
 193                 break;
 194         }
 195
 196         nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
 197         if (!other_dst)
 198                 return -ENOENT;
 199
 200         nft_default_forward_path(route, this_dst, dir);
 201         nft_default_forward_path(route, other_dst, !dir);
 202
 203         if (route->tuple[dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH &&
 204             route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
 205                 nft_dev_forward_path(route, ct, dir, ft);
 206                 nft_dev_forward_path(route, ct, !dir, ft);
 207         }
 208
 209         return 0;
 210 }
 211
 212 static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
 213 {
 214         if (skb_sec_path(skb))
 215                 return true;
 216
 217         if (family == NFPROTO_IPV4) {
 218                 const struct ip_options *opt;
 219
 220                 opt = &(IPCB(skb)->opt);
 221
 222                 if (unlikely(opt->optlen))
 223                         return true;
 224         }
 225
 226         return false;
 227 }
 228
 229 static void nft_flow_offload_eval(const struct nft_expr *expr,
 230                                   struct nft_regs *regs,
 231                                   const struct nft_pktinfo *pkt)
 232 {
 233         struct nft_flow_offload *priv = nft_expr_priv(expr);
 234         struct nf_flowtable *flowtable = &priv->flowtable->data;
 235         struct tcphdr _tcph, *tcph = NULL;
 236         struct nf_flow_route route = {};
 237         enum ip_conntrack_info ctinfo;
 238         struct flow_offload *flow;
 239         enum ip_conntrack_dir dir;
 240         struct nf_conn *ct;
 241         int ret;
 242
 243         if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
 244                 goto out;
 245
 246         ct = nf_ct_get(pkt->skb, &ctinfo);
 247         if (!ct)
 248                 goto out;
 249
 250         switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
 251         case IPPROTO_TCP:
 252                 tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff,
 253                                           sizeof(_tcph), &_tcph);
 254                 if (unlikely(!tcph || tcph->fin || tcph->rst))
 255                         goto out;
 256                 break;
 257         case IPPROTO_UDP:
 258                 break;
 259         default:
 260                 goto out;
 261         }
 262
 263         if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
 264             ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
 265                 goto out;
 266
 267         if (!nf_ct_is_confirmed(ct))
 268                 goto out;
 269
 270         if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
 271                 goto out;
 272
 273         dir = CTINFO2DIR(ctinfo);
 274         if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
 275                 goto err_flow_route;
 276
 277         flow = flow_offload_alloc(ct);
 278         if (!flow)
 279                 goto err_flow_alloc;
 280
 281         if (flow_offload_route_init(flow, &route) < 0)
 282                 goto err_flow_add;
 283
 284         if (tcph) {
 285                 ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 286                 ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 287         }
 288
 289         ret = flow_offload_add(flowtable, flow);
 290         if (ret < 0)
 291                 goto err_flow_add;
 292
 293         dst_release(route.tuple[!dir].dst);
 294         return;
 295
 296 err_flow_add:
 297         flow_offload_free(flow);
 298 err_flow_alloc:
 299         dst_release(route.tuple[!dir].dst);
 300 err_flow_route:
 301         clear_bit(IPS_OFFLOAD_BIT, &ct->status);
 302 out:
 303         regs->verdict.code = NFT_BREAK;
 304 }
 305
 306 static int nft_flow_offload_validate(const struct nft_ctx *ctx,
 307                                      const struct nft_expr *expr,
 308                                      const struct nft_data **data)
 309 {
 310         unsigned int hook_mask = (1 << NF_INET_FORWARD);
 311
 312         return nft_chain_validate_hooks(ctx->chain, hook_mask);
 313 }
 314
 315 static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
 316         [NFTA_FLOW_TABLE_NAME]  = { .type = NLA_STRING,
 317                                     .len = NFT_NAME_MAXLEN - 1 },
 318 };
 319
 320 static int nft_flow_offload_init(const struct nft_ctx *ctx,
 321                                  const struct nft_expr *expr,
 322                                  const struct nlattr * const tb[])
 323 {
 324         struct nft_flow_offload *priv = nft_expr_priv(expr);
 325         u8 genmask = nft_genmask_next(ctx->net);
 326         struct nft_flowtable *flowtable;
 327
 328         if (!tb[NFTA_FLOW_TABLE_NAME])
 329                 return -EINVAL;
 330
 331         flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
 332                                          genmask);
 333         if (IS_ERR(flowtable))
 334                 return PTR_ERR(flowtable);
 335
 336         priv->flowtable = flowtable;
 337         flowtable->use++;
 338
 339         return nf_ct_netns_get(ctx->net, ctx->family);
 340 }
 341
 342 static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
 343                                         const struct nft_expr *expr,
 344                                         enum nft_trans_phase phase)
 345 {
 346         struct nft_flow_offload *priv = nft_expr_priv(expr);
 347
 348         nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
 349 }
 350
 351 static void nft_flow_offload_activate(const struct nft_ctx *ctx,
 352                                       const struct nft_expr *expr)
 353 {
 354         struct nft_flow_offload *priv = nft_expr_priv(expr);
 355
 356         priv->flowtable->use++;
 357 }
 358
 359 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
 360                                      const struct nft_expr *expr)
 361 {
 362         nf_ct_netns_put(ctx->net, ctx->family);
 363 }
 364
 365 static int nft_flow_offload_dump(struct sk_buff *skb, const struct nft_expr *expr)
 366 {
 367         struct nft_flow_offload *priv = nft_expr_priv(expr);
 368
 369         if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
 370                 goto nla_put_failure;
 371
 372         return 0;
 373
 374 nla_put_failure:
 375         return -1;
 376 }
 377
 378 static struct nft_expr_type nft_flow_offload_type;
 379 static const struct nft_expr_ops nft_flow_offload_ops = {
 380         .type           = &nft_flow_offload_type,
 381         .size           = NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
 382         .eval           = nft_flow_offload_eval,
 383         .init           = nft_flow_offload_init,
 384         .activate       = nft_flow_offload_activate,
 385         .deactivate     = nft_flow_offload_deactivate,
 386         .destroy        = nft_flow_offload_destroy,
 387         .validate       = nft_flow_offload_validate,
 388         .dump           = nft_flow_offload_dump,
 389 };
 390
 391 static struct nft_expr_type nft_flow_offload_type __read_mostly = {
 392         .name           = "flow_offload",
 393         .ops            = &nft_flow_offload_ops,
 394         .policy         = nft_flow_offload_policy,
 395         .maxattr        = NFTA_FLOW_MAX,
 396         .owner          = THIS_MODULE,
 397 };
 398
 399 static int flow_offload_netdev_event(struct notifier_block *this,
 400                                      unsigned long event, void *ptr)
 401 {
 402         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 403
 404         if (event != NETDEV_DOWN)
 405                 return NOTIFY_DONE;
 406
 407         nf_flow_table_cleanup(dev);
 408
 409         return NOTIFY_DONE;
 410 }
 411
 412 static struct notifier_block flow_offload_netdev_notifier = {
 413         .notifier_call  = flow_offload_netdev_event,
 414 };
 415
 416 static int __init nft_flow_offload_module_init(void)
 417 {
 418         int err;
 419
 420         err = register_netdevice_notifier(&flow_offload_netdev_notifier);
 421         if (err)
 422                 goto err;
 423
 424         err = nft_register_expr(&nft_flow_offload_type);
 425         if (err < 0)
 426                 goto register_expr;
 427
 428         return 0;
 429
 430 register_expr:
 431         unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 432 err:
 433         return err;
 434 }
 435
 436 static void __exit nft_flow_offload_module_exit(void)
 437 {
 438         nft_unregister_expr(&nft_flow_offload_type);
 439         unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 440 }
 441
 442 module_init(nft_flow_offload_module_init);
 443 module_exit(nft_flow_offload_module_exit);
 444
 445 MODULE_LICENSE("GPL");
 446 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 447 MODULE_ALIAS_NFT_EXPR("flow_offload");
 448 MODULE_DESCRIPTION("nftables hardware flow offload module");