net/netfilter/nf_flow_table_core.c

   1 #include <linux/kernel.h>
   2 #include <linux/init.h>
   3 #include <linux/module.h>
   4 #include <linux/netfilter.h>
   5 #include <linux/rhashtable.h>
   6 #include <linux/netdevice.h>
   7 #include <net/ip.h>
   8 #include <net/ip6_route.h>
   9 #include <net/netfilter/nf_tables.h>
  10 #include <net/netfilter/nf_flow_table.h>
  11 #include <net/netfilter/nf_conntrack.h>
  12 #include <net/netfilter/nf_conntrack_core.h>
  13 #include <net/netfilter/nf_conntrack_tuple.h>
  14
  15 struct flow_offload_entry {
  16         struct flow_offload     flow;
  17         struct nf_conn          *ct;
  18         struct rcu_head         rcu_head;
  19 };
  20
  21 static DEFINE_MUTEX(flowtable_lock);
  22 static LIST_HEAD(flowtables);
  23
  24 static void
  25 flow_offload_fill_dir(struct flow_offload *flow, struct nf_conn *ct,
  26                       struct nf_flow_route *route,
  27                       enum flow_offload_tuple_dir dir)
  28 {
  29         struct flow_offload_tuple *ft = &flow->tuplehash[dir].tuple;
  30         struct nf_conntrack_tuple *ctt = &ct->tuplehash[dir].tuple;
  31         struct dst_entry *other_dst = route->tuple[!dir].dst;
  32         struct dst_entry *dst = route->tuple[dir].dst;
  33
  34         ft->dir = dir;
  35
  36         switch (ctt->src.l3num) {
  37         case NFPROTO_IPV4:
  38                 ft->src_v4 = ctt->src.u3.in;
  39                 ft->dst_v4 = ctt->dst.u3.in;
  40                 ft->mtu = ip_dst_mtu_maybe_forward(dst, true);
  41                 break;
  42         case NFPROTO_IPV6:
  43                 ft->src_v6 = ctt->src.u3.in6;
  44                 ft->dst_v6 = ctt->dst.u3.in6;
  45                 ft->mtu = ip6_dst_mtu_forward(dst);
  46                 break;
  47         }
  48
  49         ft->l3proto = ctt->src.l3num;
  50         ft->l4proto = ctt->dst.protonum;
  51         ft->src_port = ctt->src.u.tcp.port;
  52         ft->dst_port = ctt->dst.u.tcp.port;
  53
  54         ft->iifidx = other_dst->dev->ifindex;
  55         ft->oifidx = dst->dev->ifindex;
  56         ft->dst_cache = dst;
  57 }
  58
  59 struct flow_offload *
  60 flow_offload_alloc(struct nf_conn *ct, struct nf_flow_route *route)
  61 {
  62         struct flow_offload_entry *entry;
  63         struct flow_offload *flow;
  64
  65         if (unlikely(nf_ct_is_dying(ct) ||
  66             !atomic_inc_not_zero(&ct->ct_general.use)))
  67                 return NULL;
  68
  69         entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
  70         if (!entry)
  71                 goto err_ct_refcnt;
  72
  73         flow = &entry->flow;
  74
  75         if (!dst_hold_safe(route->tuple[FLOW_OFFLOAD_DIR_ORIGINAL].dst))
  76                 goto err_dst_cache_original;
  77
  78         if (!dst_hold_safe(route->tuple[FLOW_OFFLOAD_DIR_REPLY].dst))
  79                 goto err_dst_cache_reply;
  80
  81         entry->ct = ct;
  82
  83         flow_offload_fill_dir(flow, ct, route, FLOW_OFFLOAD_DIR_ORIGINAL);
  84         flow_offload_fill_dir(flow, ct, route, FLOW_OFFLOAD_DIR_REPLY);
  85
  86         if (ct->status & IPS_SRC_NAT)
  87                 flow->flags |= FLOW_OFFLOAD_SNAT;
  88         if (ct->status & IPS_DST_NAT)
  89                 flow->flags |= FLOW_OFFLOAD_DNAT;
  90
  91         return flow;
  92
  93 err_dst_cache_reply:
  94         dst_release(route->tuple[FLOW_OFFLOAD_DIR_ORIGINAL].dst);
  95 err_dst_cache_original:
  96         kfree(entry);
  97 err_ct_refcnt:
  98         nf_ct_put(ct);
  99
 100         return NULL;
 101 }
 102 EXPORT_SYMBOL_GPL(flow_offload_alloc);
 103
 104 static void flow_offload_fixup_tcp(struct ip_ct_tcp *tcp)
 105 {
 106         tcp->state = TCP_CONNTRACK_ESTABLISHED;
 107         tcp->seen[0].td_maxwin = 0;
 108         tcp->seen[1].td_maxwin = 0;
 109 }
 110
 111 #define NF_FLOWTABLE_TCP_PICKUP_TIMEOUT (120 * HZ)
 112 #define NF_FLOWTABLE_UDP_PICKUP_TIMEOUT (30 * HZ)
 113
 114 static void flow_offload_fixup_ct_state(struct nf_conn *ct)
 115 {
 116         const struct nf_conntrack_l4proto *l4proto;
 117         unsigned int timeout;
 118         int l4num;
 119
 120         l4num = nf_ct_protonum(ct);
 121         if (l4num == IPPROTO_TCP)
 122                 flow_offload_fixup_tcp(&ct->proto.tcp);
 123
 124         l4proto = __nf_ct_l4proto_find(l4num);
 125         if (!l4proto)
 126                 return;
 127
 128         if (l4num == IPPROTO_TCP)
 129                 timeout = NF_FLOWTABLE_TCP_PICKUP_TIMEOUT;
 130         else if (l4num == IPPROTO_UDP)
 131                 timeout = NF_FLOWTABLE_UDP_PICKUP_TIMEOUT;
 132         else
 133                 return;
 134
 135         ct->timeout = nfct_time_stamp + timeout;
 136 }
 137
 138 void flow_offload_free(struct flow_offload *flow)
 139 {
 140         struct flow_offload_entry *e;
 141
 142         dst_release(flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_cache);
 143         dst_release(flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_cache);
 144         e = container_of(flow, struct flow_offload_entry, flow);
 145         if (flow->flags & FLOW_OFFLOAD_DYING)
 146                 nf_ct_delete(e->ct, 0, 0);
 147         nf_ct_put(e->ct);
 148         kfree_rcu(e, rcu_head);
 149 }
 150 EXPORT_SYMBOL_GPL(flow_offload_free);
 151
 152 static u32 flow_offload_hash(const void *data, u32 len, u32 seed)
 153 {
 154         const struct flow_offload_tuple *tuple = data;
 155
 156         return jhash(tuple, offsetof(struct flow_offload_tuple, dir), seed);
 157 }
 158
 159 static u32 flow_offload_hash_obj(const void *data, u32 len, u32 seed)
 160 {
 161         const struct flow_offload_tuple_rhash *tuplehash = data;
 162
 163         return jhash(&tuplehash->tuple, offsetof(struct flow_offload_tuple, dir), seed);
 164 }
 165
 166 static int flow_offload_hash_cmp(struct rhashtable_compare_arg *arg,
 167                                         const void *ptr)
 168 {
 169         const struct flow_offload_tuple *tuple = arg->key;
 170         const struct flow_offload_tuple_rhash *x = ptr;
 171
 172         if (memcmp(&x->tuple, tuple, offsetof(struct flow_offload_tuple, dir)))
 173                 return 1;
 174
 175         return 0;
 176 }
 177
 178 static const struct rhashtable_params nf_flow_offload_rhash_params = {
 179         .head_offset            = offsetof(struct flow_offload_tuple_rhash, node),
 180         .hashfn                 = flow_offload_hash,
 181         .obj_hashfn             = flow_offload_hash_obj,
 182         .obj_cmpfn              = flow_offload_hash_cmp,
 183         .automatic_shrinking    = true,
 184 };
 185
 186 int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow)
 187 {
 188         flow->timeout = (u32)jiffies;
 189
 190         rhashtable_insert_fast(&flow_table->rhashtable,
 191                                &flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].node,
 192                                nf_flow_offload_rhash_params);
 193         rhashtable_insert_fast(&flow_table->rhashtable,
 194                                &flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].node,
 195                                nf_flow_offload_rhash_params);
 196         return 0;
 197 }
 198 EXPORT_SYMBOL_GPL(flow_offload_add);
 199
 200 static void flow_offload_del(struct nf_flowtable *flow_table,
 201                              struct flow_offload *flow)
 202 {
 203         struct flow_offload_entry *e;
 204
 205         rhashtable_remove_fast(&flow_table->rhashtable,
 206                                &flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].node,
 207                                nf_flow_offload_rhash_params);
 208         rhashtable_remove_fast(&flow_table->rhashtable,
 209                                &flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].node,
 210                                nf_flow_offload_rhash_params);
 211
 212         e = container_of(flow, struct flow_offload_entry, flow);
 213         clear_bit(IPS_OFFLOAD_BIT, &e->ct->status);
 214
 215         flow_offload_free(flow);
 216 }
 217
 218 void flow_offload_teardown(struct flow_offload *flow)
 219 {
 220         struct flow_offload_entry *e;
 221
 222         flow->flags |= FLOW_OFFLOAD_TEARDOWN;
 223
 224         e = container_of(flow, struct flow_offload_entry, flow);
 225         flow_offload_fixup_ct_state(e->ct);
 226 }
 227 EXPORT_SYMBOL_GPL(flow_offload_teardown);
 228
 229 struct flow_offload_tuple_rhash *
 230 flow_offload_lookup(struct nf_flowtable *flow_table,
 231                     struct flow_offload_tuple *tuple)
 232 {
 233         struct flow_offload_tuple_rhash *tuplehash;
 234         struct flow_offload *flow;
 235         int dir;
 236
 237         tuplehash = rhashtable_lookup(&flow_table->rhashtable, tuple,
 238                                       nf_flow_offload_rhash_params);
 239         if (!tuplehash)
 240                 return NULL;
 241
 242         dir = tuplehash->tuple.dir;
 243         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 244         if (flow->flags & (FLOW_OFFLOAD_DYING | FLOW_OFFLOAD_TEARDOWN))
 245                 return NULL;
 246
 247         return tuplehash;
 248 }
 249 EXPORT_SYMBOL_GPL(flow_offload_lookup);
 250
 251 static int
 252 nf_flow_table_iterate(struct nf_flowtable *flow_table,
 253                       void (*iter)(struct flow_offload *flow, void *data),
 254                       void *data)
 255 {
 256         struct flow_offload_tuple_rhash *tuplehash;
 257         struct rhashtable_iter hti;
 258         struct flow_offload *flow;
 259         int err = 0;
 260
 261         rhashtable_walk_enter(&flow_table->rhashtable, &hti);
 262         rhashtable_walk_start(&hti);
 263
 264         while ((tuplehash = rhashtable_walk_next(&hti))) {
 265                 if (IS_ERR(tuplehash)) {
 266                         if (PTR_ERR(tuplehash) != -EAGAIN) {
 267                                 err = PTR_ERR(tuplehash);
 268                                 break;
 269                         }
 270                         continue;
 271                 }
 272                 if (tuplehash->tuple.dir)
 273                         continue;
 274
 275                 flow = container_of(tuplehash, struct flow_offload, tuplehash[0]);
 276
 277                 iter(flow, data);
 278         }
 279         rhashtable_walk_stop(&hti);
 280         rhashtable_walk_exit(&hti);
 281
 282         return err;
 283 }
 284
 285 static inline bool nf_flow_has_expired(const struct flow_offload *flow)
 286 {
 287         return (__s32)(flow->timeout - (u32)jiffies) <= 0;
 288 }
 289
 290 static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
 291 {
 292         struct nf_flowtable *flow_table = data;
 293
 294         if (nf_flow_has_expired(flow) ||
 295             (flow->flags & (FLOW_OFFLOAD_DYING | FLOW_OFFLOAD_TEARDOWN)))
 296                 flow_offload_del(flow_table, flow);
 297 }
 298
 299 static void nf_flow_offload_work_gc(struct work_struct *work)
 300 {
 301         struct nf_flowtable *flow_table;
 302
 303         flow_table = container_of(work, struct nf_flowtable, gc_work.work);
 304         nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step, flow_table);
 305         queue_delayed_work(system_power_efficient_wq, &flow_table->gc_work, HZ);
 306 }
 307
 308 static int nf_flow_nat_port_tcp(struct sk_buff *skb, unsigned int thoff,
 309                                 __be16 port, __be16 new_port)
 310 {
 311         struct tcphdr *tcph;
 312
 313         if (!pskb_may_pull(skb, thoff + sizeof(*tcph)) ||
 314             skb_try_make_writable(skb, thoff + sizeof(*tcph)))
 315                 return -1;
 316
 317         tcph = (void *)(skb_network_header(skb) + thoff);
 318         inet_proto_csum_replace2(&tcph->check, skb, port, new_port, true);
 319
 320         return 0;
 321 }
 322
 323 static int nf_flow_nat_port_udp(struct sk_buff *skb, unsigned int thoff,
 324                                 __be16 port, __be16 new_port)
 325 {
 326         struct udphdr *udph;
 327
 328         if (!pskb_may_pull(skb, thoff + sizeof(*udph)) ||
 329             skb_try_make_writable(skb, thoff + sizeof(*udph)))
 330                 return -1;
 331
 332         udph = (void *)(skb_network_header(skb) + thoff);
 333         if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 334                 inet_proto_csum_replace2(&udph->check, skb, port,
 335                                          new_port, true);
 336                 if (!udph->check)
 337                         udph->check = CSUM_MANGLED_0;
 338         }
 339
 340         return 0;
 341 }
 342
 343 static int nf_flow_nat_port(struct sk_buff *skb, unsigned int thoff,
 344                             u8 protocol, __be16 port, __be16 new_port)
 345 {
 346         switch (protocol) {
 347         case IPPROTO_TCP:
 348                 if (nf_flow_nat_port_tcp(skb, thoff, port, new_port) < 0)
 349                         return NF_DROP;
 350                 break;
 351         case IPPROTO_UDP:
 352                 if (nf_flow_nat_port_udp(skb, thoff, port, new_port) < 0)
 353                         return NF_DROP;
 354                 break;
 355         }
 356
 357         return 0;
 358 }
 359
 360 int nf_flow_snat_port(const struct flow_offload *flow,
 361                       struct sk_buff *skb, unsigned int thoff,
 362                       u8 protocol, enum flow_offload_tuple_dir dir)
 363 {
 364         struct flow_ports *hdr;
 365         __be16 port, new_port;
 366
 367         if (!pskb_may_pull(skb, thoff + sizeof(*hdr)) ||
 368             skb_try_make_writable(skb, thoff + sizeof(*hdr)))
 369                 return -1;
 370
 371         hdr = (void *)(skb_network_header(skb) + thoff);
 372
 373         switch (dir) {
 374         case FLOW_OFFLOAD_DIR_ORIGINAL:
 375                 port = hdr->source;
 376                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_port;
 377                 hdr->source = new_port;
 378                 break;
 379         case FLOW_OFFLOAD_DIR_REPLY:
 380                 port = hdr->dest;
 381                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_port;
 382                 hdr->dest = new_port;
 383                 break;
 384         default:
 385                 return -1;
 386         }
 387
 388         return nf_flow_nat_port(skb, thoff, protocol, port, new_port);
 389 }
 390 EXPORT_SYMBOL_GPL(nf_flow_snat_port);
 391
 392 int nf_flow_dnat_port(const struct flow_offload *flow,
 393                       struct sk_buff *skb, unsigned int thoff,
 394                       u8 protocol, enum flow_offload_tuple_dir dir)
 395 {
 396         struct flow_ports *hdr;
 397         __be16 port, new_port;
 398
 399         if (!pskb_may_pull(skb, thoff + sizeof(*hdr)) ||
 400             skb_try_make_writable(skb, thoff + sizeof(*hdr)))
 401                 return -1;
 402
 403         hdr = (void *)(skb_network_header(skb) + thoff);
 404
 405         switch (dir) {
 406         case FLOW_OFFLOAD_DIR_ORIGINAL:
 407                 port = hdr->dest;
 408                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_port;
 409                 hdr->dest = new_port;
 410                 break;
 411         case FLOW_OFFLOAD_DIR_REPLY:
 412                 port = hdr->source;
 413                 new_port = flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_port;
 414                 hdr->source = new_port;
 415                 break;
 416         default:
 417                 return -1;
 418         }
 419
 420         return nf_flow_nat_port(skb, thoff, protocol, port, new_port);
 421 }
 422 EXPORT_SYMBOL_GPL(nf_flow_dnat_port);
 423
 424 int nf_flow_table_init(struct nf_flowtable *flowtable)
 425 {
 426         int err;
 427
 428         INIT_DEFERRABLE_WORK(&flowtable->gc_work, nf_flow_offload_work_gc);
 429
 430         err = rhashtable_init(&flowtable->rhashtable,
 431                               &nf_flow_offload_rhash_params);
 432         if (err < 0)
 433                 return err;
 434
 435         queue_delayed_work(system_power_efficient_wq,
 436                            &flowtable->gc_work, HZ);
 437
 438         mutex_lock(&flowtable_lock);
 439         list_add(&flowtable->list, &flowtables);
 440         mutex_unlock(&flowtable_lock);
 441
 442         return 0;
 443 }
 444 EXPORT_SYMBOL_GPL(nf_flow_table_init);
 445
 446 static void nf_flow_table_do_cleanup(struct flow_offload *flow, void *data)
 447 {
 448         struct net_device *dev = data;
 449         struct flow_offload_entry *e;
 450
 451         e = container_of(flow, struct flow_offload_entry, flow);
 452
 453         if (!dev) {
 454                 flow_offload_teardown(flow);
 455                 return;
 456         }
 457         if (net_eq(nf_ct_net(e->ct), dev_net(dev)) &&
 458             (flow->tuplehash[0].tuple.iifidx == dev->ifindex ||
 459              flow->tuplehash[1].tuple.iifidx == dev->ifindex))
 460                 flow_offload_dead(flow);
 461 }
 462
 463 static void nf_flow_table_iterate_cleanup(struct nf_flowtable *flowtable,
 464                                           struct net_device *dev)
 465 {
 466         nf_flow_table_iterate(flowtable, nf_flow_table_do_cleanup, dev);
 467         flush_delayed_work(&flowtable->gc_work);
 468 }
 469
 470 void nf_flow_table_cleanup(struct net_device *dev)
 471 {
 472         struct nf_flowtable *flowtable;
 473
 474         mutex_lock(&flowtable_lock);
 475         list_for_each_entry(flowtable, &flowtables, list)
 476                 nf_flow_table_iterate_cleanup(flowtable, dev);
 477         mutex_unlock(&flowtable_lock);
 478 }
 479 EXPORT_SYMBOL_GPL(nf_flow_table_cleanup);
 480
 481 void nf_flow_table_free(struct nf_flowtable *flow_table)
 482 {
 483         mutex_lock(&flowtable_lock);
 484         list_del(&flow_table->list);
 485         mutex_unlock(&flowtable_lock);
 486         cancel_delayed_work_sync(&flow_table->gc_work);
 487         nf_flow_table_iterate(flow_table, nf_flow_table_do_cleanup, NULL);
 488         nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step, flow_table);
 489         rhashtable_destroy(&flow_table->rhashtable);
 490 }
 491 EXPORT_SYMBOL_GPL(nf_flow_table_free);
 492
 493 MODULE_LICENSE("GPL");
 494 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");