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