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 bool nft_is_valid_ether_device(const struct net_device *dev)
  40 {
  41         if (!dev || (dev->flags & IFF_LOOPBACK) || dev->type != ARPHRD_ETHER ||
  42             dev->addr_len != ETH_ALEN || !is_valid_ether_addr(dev->dev_addr))
  43                 return false;
  44
  45         return true;
  46 }
  47
  48 static int nft_dev_fill_forward_path(const struct nf_flow_route *route,
  49                                      const struct dst_entry *dst_cache,
  50                                      const struct nf_conn *ct,
  51                                      enum ip_conntrack_dir dir, u8 *ha,
  52                                      struct net_device_path_stack *stack)
  53 {
  54         const void *daddr = &ct->tuplehash[!dir].tuple.src.u3;
  55         struct net_device *dev = dst_cache->dev;
  56         struct neighbour *n;
  57         u8 nud_state;
  58
  59         if (!nft_is_valid_ether_device(dev))
  60                 goto out;
  61
  62         n = dst_neigh_lookup(dst_cache, daddr);
  63         if (!n)
  64                 return -1;
  65
  66         read_lock_bh(&n->lock);
  67         nud_state = n->nud_state;
  68         ether_addr_copy(ha, n->ha);
  69         read_unlock_bh(&n->lock);
  70         neigh_release(n);
  71
  72         if (!(nud_state & NUD_VALID))
  73                 return -1;
  74
  75 out:
  76         return dev_fill_forward_path(dev, ha, stack);
  77 }
  78
  79 struct nft_forward_info {
  80         const struct net_device *indev;
  81         const struct net_device *outdev;
  82         const struct net_device *hw_outdev;
  83         struct id {
  84                 __u16   id;
  85                 __be16  proto;
  86         } encap[NF_FLOW_TABLE_ENCAP_MAX];
  87         u8 num_encaps;
  88         u8 ingress_vlans;
  89         u8 h_source[ETH_ALEN];
  90         u8 h_dest[ETH_ALEN];
  91         enum flow_offload_xmit_type xmit_type;
  92 };
  93
  94 static void nft_dev_path_info(const struct net_device_path_stack *stack,
  95                               struct nft_forward_info *info,
  96                               unsigned char *ha, struct nf_flowtable *flowtable)
  97 {
  98         const struct net_device_path *path;
  99         int i;
 100
 101         memcpy(info->h_dest, ha, ETH_ALEN);
 102
 103         for (i = 0; i < stack->num_paths; i++) {
 104                 path = &stack->path[i];
 105                 switch (path->type) {
 106                 case DEV_PATH_ETHERNET:
 107                 case DEV_PATH_DSA:
 108                 case DEV_PATH_VLAN:
 109                 case DEV_PATH_PPPOE:
 110                         info->indev = path->dev;
 111                         if (is_zero_ether_addr(info->h_source))
 112                                 memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
 113
 114                         if (path->type == DEV_PATH_ETHERNET)
 115                                 break;
 116                         if (path->type == DEV_PATH_DSA) {
 117                                 i = stack->num_paths;
 118                                 break;
 119                         }
 120
 121                         /* DEV_PATH_VLAN and DEV_PATH_PPPOE */
 122                         if (info->num_encaps >= NF_FLOW_TABLE_ENCAP_MAX) {
 123                                 info->indev = NULL;
 124                                 break;
 125                         }
 126                         if (!info->outdev)
 127                                 info->outdev = path->dev;
 128                         info->encap[info->num_encaps].id = path->encap.id;
 129                         info->encap[info->num_encaps].proto = path->encap.proto;
 130                         info->num_encaps++;
 131                         if (path->type == DEV_PATH_PPPOE)
 132                                 memcpy(info->h_dest, path->encap.h_dest, ETH_ALEN);
 133                         break;
 134                 case DEV_PATH_BRIDGE:
 135                         if (is_zero_ether_addr(info->h_source))
 136                                 memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
 137
 138                         switch (path->bridge.vlan_mode) {
 139                         case DEV_PATH_BR_VLAN_UNTAG_HW:
 140                                 info->ingress_vlans |= BIT(info->num_encaps - 1);
 141                                 break;
 142                         case DEV_PATH_BR_VLAN_TAG:
 143                                 info->encap[info->num_encaps].id = path->bridge.vlan_id;
 144                                 info->encap[info->num_encaps].proto = path->bridge.vlan_proto;
 145                                 info->num_encaps++;
 146                                 break;
 147                         case DEV_PATH_BR_VLAN_UNTAG:
 148                                 info->num_encaps--;
 149                                 break;
 150                         case DEV_PATH_BR_VLAN_KEEP:
 151                                 break;
 152                         }
 153                         info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
 154                         break;
 155                 default:
 156                         info->indev = NULL;
 157                         break;
 158                 }
 159         }
 160         if (!info->outdev)
 161                 info->outdev = info->indev;
 162
 163         info->hw_outdev = info->indev;
 164
 165         if (nf_flowtable_hw_offload(flowtable) &&
 166             nft_is_valid_ether_device(info->indev))
 167                 info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
 168 }
 169
 170 static bool nft_flowtable_find_dev(const struct net_device *dev,
 171                                    struct nft_flowtable *ft)
 172 {
 173         struct nft_hook *hook;
 174         bool found = false;
 175
 176         list_for_each_entry_rcu(hook, &ft->hook_list, list) {
 177                 if (hook->ops.dev != dev)
 178                         continue;
 179
 180                 found = true;
 181                 break;
 182         }
 183
 184         return found;
 185 }
 186
 187 static void nft_dev_forward_path(struct nf_flow_route *route,
 188                                  const struct nf_conn *ct,
 189                                  enum ip_conntrack_dir dir,
 190                                  struct nft_flowtable *ft)
 191 {
 192         const struct dst_entry *dst = route->tuple[dir].dst;
 193         struct net_device_path_stack stack;
 194         struct nft_forward_info info = {};
 195         unsigned char ha[ETH_ALEN];
 196         int i;
 197
 198         if (nft_dev_fill_forward_path(route, dst, ct, dir, ha, &stack) >= 0)
 199                 nft_dev_path_info(&stack, &info, ha, &ft->data);
 200
 201         if (!info.indev || !nft_flowtable_find_dev(info.indev, ft))
 202                 return;
 203
 204         route->tuple[!dir].in.ifindex = info.indev->ifindex;
 205         for (i = 0; i < info.num_encaps; i++) {
 206                 route->tuple[!dir].in.encap[i].id = info.encap[i].id;
 207                 route->tuple[!dir].in.encap[i].proto = info.encap[i].proto;
 208         }
 209         route->tuple[!dir].in.num_encaps = info.num_encaps;
 210         route->tuple[!dir].in.ingress_vlans = info.ingress_vlans;
 211
 212         if (info.xmit_type == FLOW_OFFLOAD_XMIT_DIRECT) {
 213                 memcpy(route->tuple[dir].out.h_source, info.h_source, ETH_ALEN);
 214                 memcpy(route->tuple[dir].out.h_dest, info.h_dest, ETH_ALEN);
 215                 route->tuple[dir].out.ifindex = info.outdev->ifindex;
 216                 route->tuple[dir].out.hw_ifindex = info.hw_outdev->ifindex;
 217                 route->tuple[dir].xmit_type = info.xmit_type;
 218         }
 219 }
 220
 221 static int nft_flow_route(const struct nft_pktinfo *pkt,
 222                           const struct nf_conn *ct,
 223                           struct nf_flow_route *route,
 224                           enum ip_conntrack_dir dir,
 225                           struct nft_flowtable *ft)
 226 {
 227         struct dst_entry *this_dst = skb_dst(pkt->skb);
 228         struct dst_entry *other_dst = NULL;
 229         struct flowi fl;
 230
 231         memset(&fl, 0, sizeof(fl));
 232         switch (nft_pf(pkt)) {
 233         case NFPROTO_IPV4:
 234                 fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
 235                 fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
 236                 break;
 237         case NFPROTO_IPV6:
 238                 fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
 239                 fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
 240                 break;
 241         }
 242
 243         nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
 244         if (!other_dst)
 245                 return -ENOENT;
 246
 247         nft_default_forward_path(route, this_dst, dir);
 248         nft_default_forward_path(route, other_dst, !dir);
 249
 250         if (route->tuple[dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH &&
 251             route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
 252                 nft_dev_forward_path(route, ct, dir, ft);
 253                 nft_dev_forward_path(route, ct, !dir, ft);
 254         }
 255
 256         return 0;
 257 }
 258
 259 static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
 260 {
 261         if (skb_sec_path(skb))
 262                 return true;
 263
 264         if (family == NFPROTO_IPV4) {
 265                 const struct ip_options *opt;
 266
 267                 opt = &(IPCB(skb)->opt);
 268
 269                 if (unlikely(opt->optlen))
 270                         return true;
 271         }
 272
 273         return false;
 274 }
 275
 276 static void nft_flow_offload_eval(const struct nft_expr *expr,
 277                                   struct nft_regs *regs,
 278                                   const struct nft_pktinfo *pkt)
 279 {
 280         struct nft_flow_offload *priv = nft_expr_priv(expr);
 281         struct nf_flowtable *flowtable = &priv->flowtable->data;
 282         struct tcphdr _tcph, *tcph = NULL;
 283         struct nf_flow_route route = {};
 284         enum ip_conntrack_info ctinfo;
 285         struct flow_offload *flow;
 286         enum ip_conntrack_dir dir;
 287         struct nf_conn *ct;
 288         int ret;
 289
 290         if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
 291                 goto out;
 292
 293         ct = nf_ct_get(pkt->skb, &ctinfo);
 294         if (!ct)
 295                 goto out;
 296
 297         switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
 298         case IPPROTO_TCP:
 299                 tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt),
 300                                           sizeof(_tcph), &_tcph);
 301                 if (unlikely(!tcph || tcph->fin || tcph->rst ||
 302                              !nf_conntrack_tcp_established(ct)))
 303                         goto out;
 304                 break;
 305         case IPPROTO_UDP:
 306                 break;
 307         default:
 308                 goto out;
 309         }
 310
 311         if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
 312             ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
 313                 goto out;
 314
 315         if (!nf_ct_is_confirmed(ct))
 316                 goto out;
 317
 318         if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
 319                 goto out;
 320
 321         dir = CTINFO2DIR(ctinfo);
 322         if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
 323                 goto err_flow_route;
 324
 325         flow = flow_offload_alloc(ct);
 326         if (!flow)
 327                 goto err_flow_alloc;
 328
 329         if (flow_offload_route_init(flow, &route) < 0)
 330                 goto err_flow_add;
 331
 332         if (tcph) {
 333                 ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 334                 ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 335         }
 336
 337         ret = flow_offload_add(flowtable, flow);
 338         if (ret < 0)
 339                 goto err_flow_add;
 340
 341         dst_release(route.tuple[!dir].dst);
 342         return;
 343
 344 err_flow_add:
 345         flow_offload_free(flow);
 346 err_flow_alloc:
 347         dst_release(route.tuple[!dir].dst);
 348 err_flow_route:
 349         clear_bit(IPS_OFFLOAD_BIT, &ct->status);
 350 out:
 351         regs->verdict.code = NFT_BREAK;
 352 }
 353
 354 static int nft_flow_offload_validate(const struct nft_ctx *ctx,
 355                                      const struct nft_expr *expr,
 356                                      const struct nft_data **data)
 357 {
 358         unsigned int hook_mask = (1 << NF_INET_FORWARD);
 359
 360         return nft_chain_validate_hooks(ctx->chain, hook_mask);
 361 }
 362
 363 static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
 364         [NFTA_FLOW_TABLE_NAME]  = { .type = NLA_STRING,
 365                                     .len = NFT_NAME_MAXLEN - 1 },
 366 };
 367
 368 static int nft_flow_offload_init(const struct nft_ctx *ctx,
 369                                  const struct nft_expr *expr,
 370                                  const struct nlattr * const tb[])
 371 {
 372         struct nft_flow_offload *priv = nft_expr_priv(expr);
 373         u8 genmask = nft_genmask_next(ctx->net);
 374         struct nft_flowtable *flowtable;
 375
 376         if (!tb[NFTA_FLOW_TABLE_NAME])
 377                 return -EINVAL;
 378
 379         flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
 380                                          genmask);
 381         if (IS_ERR(flowtable))
 382                 return PTR_ERR(flowtable);
 383
 384         priv->flowtable = flowtable;
 385         flowtable->use++;
 386
 387         return nf_ct_netns_get(ctx->net, ctx->family);
 388 }
 389
 390 static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
 391                                         const struct nft_expr *expr,
 392                                         enum nft_trans_phase phase)
 393 {
 394         struct nft_flow_offload *priv = nft_expr_priv(expr);
 395
 396         nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
 397 }
 398
 399 static void nft_flow_offload_activate(const struct nft_ctx *ctx,
 400                                       const struct nft_expr *expr)
 401 {
 402         struct nft_flow_offload *priv = nft_expr_priv(expr);
 403
 404         priv->flowtable->use++;
 405 }
 406
 407 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
 408                                      const struct nft_expr *expr)
 409 {
 410         nf_ct_netns_put(ctx->net, ctx->family);
 411 }
 412
 413 static int nft_flow_offload_dump(struct sk_buff *skb, const struct nft_expr *expr)
 414 {
 415         struct nft_flow_offload *priv = nft_expr_priv(expr);
 416
 417         if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
 418                 goto nla_put_failure;
 419
 420         return 0;
 421
 422 nla_put_failure:
 423         return -1;
 424 }
 425
 426 static struct nft_expr_type nft_flow_offload_type;
 427 static const struct nft_expr_ops nft_flow_offload_ops = {
 428         .type           = &nft_flow_offload_type,
 429         .size           = NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
 430         .eval           = nft_flow_offload_eval,
 431         .init           = nft_flow_offload_init,
 432         .activate       = nft_flow_offload_activate,
 433         .deactivate     = nft_flow_offload_deactivate,
 434         .destroy        = nft_flow_offload_destroy,
 435         .validate       = nft_flow_offload_validate,
 436         .dump           = nft_flow_offload_dump,
 437 };
 438
 439 static struct nft_expr_type nft_flow_offload_type __read_mostly = {
 440         .name           = "flow_offload",
 441         .ops            = &nft_flow_offload_ops,
 442         .policy         = nft_flow_offload_policy,
 443         .maxattr        = NFTA_FLOW_MAX,
 444         .owner          = THIS_MODULE,
 445 };
 446
 447 static int flow_offload_netdev_event(struct notifier_block *this,
 448                                      unsigned long event, void *ptr)
 449 {
 450         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 451
 452         if (event != NETDEV_DOWN)
 453                 return NOTIFY_DONE;
 454
 455         nf_flow_table_cleanup(dev);
 456
 457         return NOTIFY_DONE;
 458 }
 459
 460 static struct notifier_block flow_offload_netdev_notifier = {
 461         .notifier_call  = flow_offload_netdev_event,
 462 };
 463
 464 static int __init nft_flow_offload_module_init(void)
 465 {
 466         int err;
 467
 468         err = register_netdevice_notifier(&flow_offload_netdev_notifier);
 469         if (err)
 470                 goto err;
 471
 472         err = nft_register_expr(&nft_flow_offload_type);
 473         if (err < 0)
 474                 goto register_expr;
 475
 476         return 0;
 477
 478 register_expr:
 479         unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 480 err:
 481         return err;
 482 }
 483
 484 static void __exit nft_flow_offload_module_exit(void)
 485 {
 486         nft_unregister_expr(&nft_flow_offload_type);
 487         unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 488 }
 489
 490 module_init(nft_flow_offload_module_init);
 491 module_exit(nft_flow_offload_module_exit);
 492
 493 MODULE_LICENSE("GPL");
 494 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 495 MODULE_ALIAS_NFT_EXPR("flow_offload");
 496 MODULE_DESCRIPTION("nftables hardware flow offload module");