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>
  12 #include <net/inet_dscp.h>
  13 #include <net/netfilter/nf_tables.h>
  14 #include <net/netfilter/nf_tables_core.h>
  15 #include <net/netfilter/nf_conntrack_core.h>
  16 #include <net/netfilter/nf_conntrack_extend.h>
  17 #include <net/netfilter/nf_flow_table.h>
  18
  19 struct nft_flow_offload {
  20         struct nft_flowtable    *flowtable;
  21 };
  22
  23 static enum flow_offload_xmit_type nft_xmit_type(struct dst_entry *dst)
  24 {
  25         if (dst_xfrm(dst))
  26                 return FLOW_OFFLOAD_XMIT_XFRM;
  27
  28         return FLOW_OFFLOAD_XMIT_NEIGH;
  29 }
  30
  31 static void nft_default_forward_path(struct nf_flow_route *route,
  32                                      struct dst_entry *dst_cache,
  33                                      enum ip_conntrack_dir dir)
  34 {
  35         route->tuple[!dir].in.ifindex   = dst_cache->dev->ifindex;
  36         route->tuple[dir].dst           = dst_cache;
  37         route->tuple[dir].xmit_type     = nft_xmit_type(dst_cache);
  38 }
  39
  40 static bool nft_is_valid_ether_device(const struct net_device *dev)
  41 {
  42         if (!dev || (dev->flags & IFF_LOOPBACK) || dev->type != ARPHRD_ETHER ||
  43             dev->addr_len != ETH_ALEN || !is_valid_ether_addr(dev->dev_addr))
  44                 return false;
  45
  46         return true;
  47 }
  48
  49 static int nft_dev_fill_forward_path(const struct nf_flow_route *route,
  50                                      const struct dst_entry *dst_cache,
  51                                      const struct nf_conn *ct,
  52                                      enum ip_conntrack_dir dir, u8 *ha,
  53                                      struct net_device_path_stack *stack)
  54 {
  55         const void *daddr = &ct->tuplehash[!dir].tuple.src.u3;
  56         struct net_device *dev = dst_cache->dev;
  57         struct neighbour *n;
  58         u8 nud_state;
  59
  60         if (!nft_is_valid_ether_device(dev))
  61                 goto out;
  62
  63         n = dst_neigh_lookup(dst_cache, daddr);
  64         if (!n)
  65                 return -1;
  66
  67         read_lock_bh(&n->lock);
  68         nud_state = n->nud_state;
  69         ether_addr_copy(ha, n->ha);
  70         read_unlock_bh(&n->lock);
  71         neigh_release(n);
  72
  73         if (!(nud_state & NUD_VALID))
  74                 return -1;
  75
  76 out:
  77         return dev_fill_forward_path(dev, ha, stack);
  78 }
  79
  80 struct nft_forward_info {
  81         const struct net_device *indev;
  82         const struct net_device *outdev;
  83         const struct net_device *hw_outdev;
  84         struct id {
  85                 __u16   id;
  86                 __be16  proto;
  87         } encap[NF_FLOW_TABLE_ENCAP_MAX];
  88         u8 num_encaps;
  89         u8 ingress_vlans;
  90         u8 h_source[ETH_ALEN];
  91         u8 h_dest[ETH_ALEN];
  92         enum flow_offload_xmit_type xmit_type;
  93 };
  94
  95 static void nft_dev_path_info(const struct net_device_path_stack *stack,
  96                               struct nft_forward_info *info,
  97                               unsigned char *ha, struct nf_flowtable *flowtable)
  98 {
  99         const struct net_device_path *path;
 100         int i;
 101
 102         memcpy(info->h_dest, ha, ETH_ALEN);
 103
 104         for (i = 0; i < stack->num_paths; i++) {
 105                 path = &stack->path[i];
 106                 switch (path->type) {
 107                 case DEV_PATH_ETHERNET:
 108                 case DEV_PATH_DSA:
 109                 case DEV_PATH_VLAN:
 110                 case DEV_PATH_PPPOE:
 111                         info->indev = path->dev;
 112                         if (is_zero_ether_addr(info->h_source))
 113                                 memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
 114
 115                         if (path->type == DEV_PATH_ETHERNET)
 116                                 break;
 117                         if (path->type == DEV_PATH_DSA) {
 118                                 i = stack->num_paths;
 119                                 break;
 120                         }
 121
 122                         /* DEV_PATH_VLAN and DEV_PATH_PPPOE */
 123                         if (info->num_encaps >= NF_FLOW_TABLE_ENCAP_MAX) {
 124                                 info->indev = NULL;
 125                                 break;
 126                         }
 127                         if (!info->outdev)
 128                                 info->outdev = path->dev;
 129                         info->encap[info->num_encaps].id = path->encap.id;
 130                         info->encap[info->num_encaps].proto = path->encap.proto;
 131                         info->num_encaps++;
 132                         if (path->type == DEV_PATH_PPPOE)
 133                                 memcpy(info->h_dest, path->encap.h_dest, ETH_ALEN);
 134                         break;
 135                 case DEV_PATH_BRIDGE:
 136                         if (is_zero_ether_addr(info->h_source))
 137                                 memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
 138
 139                         switch (path->bridge.vlan_mode) {
 140                         case DEV_PATH_BR_VLAN_UNTAG_HW:
 141                                 info->ingress_vlans |= BIT(info->num_encaps - 1);
 142                                 break;
 143                         case DEV_PATH_BR_VLAN_TAG:
 144                                 info->encap[info->num_encaps].id = path->bridge.vlan_id;
 145                                 info->encap[info->num_encaps].proto = path->bridge.vlan_proto;
 146                                 info->num_encaps++;
 147                                 break;
 148                         case DEV_PATH_BR_VLAN_UNTAG:
 149                                 info->num_encaps--;
 150                                 break;
 151                         case DEV_PATH_BR_VLAN_KEEP:
 152                                 break;
 153                         }
 154                         info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
 155                         break;
 156                 default:
 157                         info->indev = NULL;
 158                         break;
 159                 }
 160         }
 161         if (!info->outdev)
 162                 info->outdev = info->indev;
 163
 164         info->hw_outdev = info->indev;
 165
 166         if (nf_flowtable_hw_offload(flowtable) &&
 167             nft_is_valid_ether_device(info->indev))
 168                 info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
 169 }
 170
 171 static bool nft_flowtable_find_dev(const struct net_device *dev,
 172                                    struct nft_flowtable *ft)
 173 {
 174         struct nft_hook *hook;
 175         bool found = false;
 176
 177         list_for_each_entry_rcu(hook, &ft->hook_list, list) {
 178                 if (hook->ops.dev != dev)
 179                         continue;
 180
 181                 found = true;
 182                 break;
 183         }
 184
 185         return found;
 186 }
 187
 188 static void nft_dev_forward_path(struct nf_flow_route *route,
 189                                  const struct nf_conn *ct,
 190                                  enum ip_conntrack_dir dir,
 191                                  struct nft_flowtable *ft)
 192 {
 193         const struct dst_entry *dst = route->tuple[dir].dst;
 194         struct net_device_path_stack stack;
 195         struct nft_forward_info info = {};
 196         unsigned char ha[ETH_ALEN];
 197         int i;
 198
 199         if (nft_dev_fill_forward_path(route, dst, ct, dir, ha, &stack) >= 0)
 200                 nft_dev_path_info(&stack, &info, ha, &ft->data);
 201
 202         if (!info.indev || !nft_flowtable_find_dev(info.indev, ft))
 203                 return;
 204
 205         route->tuple[!dir].in.ifindex = info.indev->ifindex;
 206         for (i = 0; i < info.num_encaps; i++) {
 207                 route->tuple[!dir].in.encap[i].id = info.encap[i].id;
 208                 route->tuple[!dir].in.encap[i].proto = info.encap[i].proto;
 209         }
 210         route->tuple[!dir].in.num_encaps = info.num_encaps;
 211         route->tuple[!dir].in.ingress_vlans = info.ingress_vlans;
 212
 213         if (info.xmit_type == FLOW_OFFLOAD_XMIT_DIRECT) {
 214                 memcpy(route->tuple[dir].out.h_source, info.h_source, ETH_ALEN);
 215                 memcpy(route->tuple[dir].out.h_dest, info.h_dest, ETH_ALEN);
 216                 route->tuple[dir].out.ifindex = info.outdev->ifindex;
 217                 route->tuple[dir].out.hw_ifindex = info.hw_outdev->ifindex;
 218                 route->tuple[dir].xmit_type = info.xmit_type;
 219         }
 220 }
 221
 222 static int nft_flow_route(const struct nft_pktinfo *pkt,
 223                           const struct nf_conn *ct,
 224                           struct nf_flow_route *route,
 225                           enum ip_conntrack_dir dir,
 226                           struct nft_flowtable *ft)
 227 {
 228         struct dst_entry *this_dst = skb_dst(pkt->skb);
 229         struct dst_entry *other_dst = NULL;
 230         struct flowi fl;
 231
 232         memset(&fl, 0, sizeof(fl));
 233         switch (nft_pf(pkt)) {
 234         case NFPROTO_IPV4:
 235                 fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
 236                 fl.u.ip4.saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
 237                 fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
 238                 fl.u.ip4.flowi4_iif = this_dst->dev->ifindex;
 239                 fl.u.ip4.flowi4_tos = inet_dscp_to_dsfield(ip4h_dscp(ip_hdr(pkt->skb)));
 240                 fl.u.ip4.flowi4_mark = pkt->skb->mark;
 241                 fl.u.ip4.flowi4_flags = FLOWI_FLAG_ANYSRC;
 242                 break;
 243         case NFPROTO_IPV6:
 244                 fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
 245                 fl.u.ip6.saddr = ct->tuplehash[!dir].tuple.src.u3.in6;
 246                 fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
 247                 fl.u.ip6.flowi6_iif = this_dst->dev->ifindex;
 248                 fl.u.ip6.flowlabel = ip6_flowinfo(ipv6_hdr(pkt->skb));
 249                 fl.u.ip6.flowi6_mark = pkt->skb->mark;
 250                 fl.u.ip6.flowi6_flags = FLOWI_FLAG_ANYSRC;
 251                 break;
 252         }
 253
 254         if (!dst_hold_safe(this_dst))
 255                 return -ENOENT;
 256
 257         nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
 258         if (!other_dst) {
 259                 dst_release(this_dst);
 260                 return -ENOENT;
 261         }
 262
 263         nft_default_forward_path(route, this_dst, dir);
 264         nft_default_forward_path(route, other_dst, !dir);
 265
 266         if (route->tuple[dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH &&
 267             route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
 268                 nft_dev_forward_path(route, ct, dir, ft);
 269                 nft_dev_forward_path(route, ct, !dir, ft);
 270         }
 271
 272         return 0;
 273 }
 274
 275 static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
 276 {
 277         if (skb_sec_path(skb))
 278                 return true;
 279
 280         if (family == NFPROTO_IPV4) {
 281                 const struct ip_options *opt;
 282
 283                 opt = &(IPCB(skb)->opt);
 284
 285                 if (unlikely(opt->optlen))
 286                         return true;
 287         }
 288
 289         return false;
 290 }
 291
 292 static void flow_offload_ct_tcp(struct nf_conn *ct)
 293 {
 294         /* conntrack will not see all packets, disable tcp window validation. */
 295         spin_lock_bh(&ct->lock);
 296         ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 297         ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
 298         spin_unlock_bh(&ct->lock);
 299 }
 300
 301 static void nft_flow_offload_eval(const struct nft_expr *expr,
 302                                   struct nft_regs *regs,
 303                                   const struct nft_pktinfo *pkt)
 304 {
 305         struct nft_flow_offload *priv = nft_expr_priv(expr);
 306         struct nf_flowtable *flowtable = &priv->flowtable->data;
 307         struct tcphdr _tcph, *tcph = NULL;
 308         struct nf_flow_route route = {};
 309         enum ip_conntrack_info ctinfo;
 310         struct flow_offload *flow;
 311         enum ip_conntrack_dir dir;
 312         struct nf_conn *ct;
 313         int ret;
 314
 315         if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
 316                 goto out;
 317
 318         ct = nf_ct_get(pkt->skb, &ctinfo);
 319         if (!ct)
 320                 goto out;
 321
 322         switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
 323         case IPPROTO_TCP:
 324                 tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt),
 325                                           sizeof(_tcph), &_tcph);
 326                 if (unlikely(!tcph || tcph->fin || tcph->rst ||
 327                              !nf_conntrack_tcp_established(ct)))
 328                         goto out;
 329                 break;
 330         case IPPROTO_UDP:
 331                 break;
 332 #ifdef CONFIG_NF_CT_PROTO_GRE
 333         case IPPROTO_GRE: {
 334                 struct nf_conntrack_tuple *tuple;
 335
 336                 if (ct->status & IPS_NAT_MASK)
 337                         goto out;
 338                 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 339                 /* No support for GRE v1 */
 340                 if (tuple->src.u.gre.key || tuple->dst.u.gre.key)
 341                         goto out;
 342                 break;
 343         }
 344 #endif
 345         default:
 346                 goto out;
 347         }
 348
 349         if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
 350             ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
 351                 goto out;
 352
 353         if (!nf_ct_is_confirmed(ct))
 354                 goto out;
 355
 356         if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
 357                 goto out;
 358
 359         dir = CTINFO2DIR(ctinfo);
 360         if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
 361                 goto err_flow_route;
 362
 363         flow = flow_offload_alloc(ct);
 364         if (!flow)
 365                 goto err_flow_alloc;
 366
 367         flow_offload_route_init(flow, &route);
 368         if (tcph)
 369                 flow_offload_ct_tcp(ct);
 370
 371         __set_bit(NF_FLOW_HW_BIDIRECTIONAL, &flow->flags);
 372         ret = flow_offload_add(flowtable, flow);
 373         if (ret < 0)
 374                 goto err_flow_add;
 375
 376         return;
 377
 378 err_flow_add:
 379         flow_offload_free(flow);
 380 err_flow_alloc:
 381         dst_release(route.tuple[dir].dst);
 382         dst_release(route.tuple[!dir].dst);
 383 err_flow_route:
 384         clear_bit(IPS_OFFLOAD_BIT, &ct->status);
 385 out:
 386         regs->verdict.code = NFT_BREAK;
 387 }
 388
 389 static int nft_flow_offload_validate(const struct nft_ctx *ctx,
 390                                      const struct nft_expr *expr)
 391 {
 392         unsigned int hook_mask = (1 << NF_INET_FORWARD);
 393
 394         if (ctx->family != NFPROTO_IPV4 &&
 395             ctx->family != NFPROTO_IPV6 &&
 396             ctx->family != NFPROTO_INET)
 397                 return -EOPNOTSUPP;
 398
 399         return nft_chain_validate_hooks(ctx->chain, hook_mask);
 400 }
 401
 402 static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
 403         [NFTA_FLOW_TABLE_NAME]  = { .type = NLA_STRING,
 404                                     .len = NFT_NAME_MAXLEN - 1 },
 405 };
 406
 407 static int nft_flow_offload_init(const struct nft_ctx *ctx,
 408                                  const struct nft_expr *expr,
 409                                  const struct nlattr * const tb[])
 410 {
 411         struct nft_flow_offload *priv = nft_expr_priv(expr);
 412         u8 genmask = nft_genmask_next(ctx->net);
 413         struct nft_flowtable *flowtable;
 414
 415         if (!tb[NFTA_FLOW_TABLE_NAME])
 416                 return -EINVAL;
 417
 418         flowtable = nft_flowtable_lookup(ctx->net, ctx->table,
 419                                          tb[NFTA_FLOW_TABLE_NAME], genmask);
 420         if (IS_ERR(flowtable))
 421                 return PTR_ERR(flowtable);
 422
 423         if (!nft_use_inc(&flowtable->use))
 424                 return -EMFILE;
 425
 426         priv->flowtable = flowtable;
 427
 428         return nf_ct_netns_get(ctx->net, ctx->family);
 429 }
 430
 431 static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
 432                                         const struct nft_expr *expr,
 433                                         enum nft_trans_phase phase)
 434 {
 435         struct nft_flow_offload *priv = nft_expr_priv(expr);
 436
 437         nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
 438 }
 439
 440 static void nft_flow_offload_activate(const struct nft_ctx *ctx,
 441                                       const struct nft_expr *expr)
 442 {
 443         struct nft_flow_offload *priv = nft_expr_priv(expr);
 444
 445         nft_use_inc_restore(&priv->flowtable->use);
 446 }
 447
 448 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
 449                                      const struct nft_expr *expr)
 450 {
 451         nf_ct_netns_put(ctx->net, ctx->family);
 452 }
 453
 454 static int nft_flow_offload_dump(struct sk_buff *skb,
 455                                  const struct nft_expr *expr, bool reset)
 456 {
 457         struct nft_flow_offload *priv = nft_expr_priv(expr);
 458
 459         if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
 460                 goto nla_put_failure;
 461
 462         return 0;
 463
 464 nla_put_failure:
 465         return -1;
 466 }
 467
 468 static struct nft_expr_type nft_flow_offload_type;
 469 static const struct nft_expr_ops nft_flow_offload_ops = {
 470         .type           = &nft_flow_offload_type,
 471         .size           = NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
 472         .eval           = nft_flow_offload_eval,
 473         .init           = nft_flow_offload_init,
 474         .activate       = nft_flow_offload_activate,
 475         .deactivate     = nft_flow_offload_deactivate,
 476         .destroy        = nft_flow_offload_destroy,
 477         .validate       = nft_flow_offload_validate,
 478         .dump           = nft_flow_offload_dump,
 479         .reduce         = NFT_REDUCE_READONLY,
 480 };
 481
 482 static struct nft_expr_type nft_flow_offload_type __read_mostly = {
 483         .name           = "flow_offload",
 484         .ops            = &nft_flow_offload_ops,
 485         .policy         = nft_flow_offload_policy,
 486         .maxattr        = NFTA_FLOW_MAX,
 487         .owner          = THIS_MODULE,
 488 };
 489
 490 static int flow_offload_netdev_event(struct notifier_block *this,
 491                                      unsigned long event, void *ptr)
 492 {
 493         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 494
 495         if (event != NETDEV_DOWN)
 496                 return NOTIFY_DONE;
 497
 498         nf_flow_table_cleanup(dev);
 499
 500         return NOTIFY_DONE;
 501 }
 502
 503 static struct notifier_block flow_offload_netdev_notifier = {
 504         .notifier_call  = flow_offload_netdev_event,
 505 };
 506
 507 static int __init nft_flow_offload_module_init(void)
 508 {
 509         int err;
 510
 511         err = register_netdevice_notifier(&flow_offload_netdev_notifier);
 512         if (err)
 513                 goto err;
 514
 515         err = nft_register_expr(&nft_flow_offload_type);
 516         if (err < 0)
 517                 goto register_expr;
 518
 519         return 0;
 520
 521 register_expr:
 522         unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 523 err:
 524         return err;
 525 }
 526
 527 static void __exit nft_flow_offload_module_exit(void)
 528 {
 529         nft_unregister_expr(&nft_flow_offload_type);
 530         unregister_netdevice_notifier(&flow_offload_netdev_notifier);
 531 }
 532
 533 module_init(nft_flow_offload_module_init);
 534 module_exit(nft_flow_offload_module_exit);
 535
 536 MODULE_LICENSE("GPL");
 537 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 538 MODULE_ALIAS_NFT_EXPR("flow_offload");
 539 MODULE_DESCRIPTION("nftables hardware flow offload module");