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