datapath/actions.c

   1 /*
   2  * Copyright (c) 2007-2014 Nicira, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301, USA
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/skbuff.h>
  22 #include <linux/in.h>
  23 #include <linux/ip.h>
  24 #include <linux/openvswitch.h>
  25 #include <linux/sctp.h>
  26 #include <linux/tcp.h>
  27 #include <linux/udp.h>
  28 #include <linux/in6.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/if_vlan.h>
  31 #include <net/ip.h>
  32 #include <net/ipv6.h>
  33 #include <net/checksum.h>
  34 #include <net/dsfield.h>
  35 #include <net/sctp/checksum.h>
  36
  37 #include "datapath.h"
  38 #include "vlan.h"
  39 #include "vport.h"
  40
  41 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  42                               const struct nlattr *attr, int len, bool keep_skb);
  43
  44 static int make_writable(struct sk_buff *skb, int write_len)
  45 {
  46         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
  47                 return 0;
  48
  49         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  50 }
  51
  52 /* remove VLAN header from packet and update csum accordingly. */
  53 static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
  54 {
  55         struct vlan_hdr *vhdr;
  56         int err;
  57
  58         err = make_writable(skb, VLAN_ETH_HLEN);
  59         if (unlikely(err))
  60                 return err;
  61
  62         if (skb->ip_summed == CHECKSUM_COMPLETE)
  63                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  64                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
  65
  66         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
  67         *current_tci = vhdr->h_vlan_TCI;
  68
  69         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
  70         __skb_pull(skb, VLAN_HLEN);
  71
  72         vlan_set_encap_proto(skb, vhdr);
  73         skb->mac_header += VLAN_HLEN;
  74         skb_reset_mac_len(skb);
  75
  76         return 0;
  77 }
  78
  79 static int pop_vlan(struct sk_buff *skb)
  80 {
  81         __be16 tci;
  82         int err;
  83
  84         if (likely(vlan_tx_tag_present(skb))) {
  85                 vlan_set_tci(skb, 0);
  86         } else {
  87                 if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
  88                              skb->len < VLAN_ETH_HLEN))
  89                         return 0;
  90
  91                 err = __pop_vlan_tci(skb, &tci);
  92                 if (err)
  93                         return err;
  94         }
  95         /* move next vlan tag to hw accel tag */
  96         if (likely(skb->protocol != htons(ETH_P_8021Q) ||
  97                    skb->len < VLAN_ETH_HLEN))
  98                 return 0;
  99
 100         err = __pop_vlan_tci(skb, &tci);
 101         if (unlikely(err))
 102                 return err;
 103
 104         __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), ntohs(tci));
 105         return 0;
 106 }
 107
 108 static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
 109 {
 110         if (unlikely(vlan_tx_tag_present(skb))) {
 111                 u16 current_tag;
 112
 113                 /* push down current VLAN tag */
 114                 current_tag = vlan_tx_tag_get(skb);
 115
 116                 if (!__vlan_put_tag(skb, skb->vlan_proto, current_tag))
 117                         return -ENOMEM;
 118
 119                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 120                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 121                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
 122
 123         }
 124         __vlan_hwaccel_put_tag(skb, vlan->vlan_tpid, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
 125         return 0;
 126 }
 127
 128 static int set_eth_addr(struct sk_buff *skb,
 129                         const struct ovs_key_ethernet *eth_key)
 130 {
 131         int err;
 132         err = make_writable(skb, ETH_HLEN);
 133         if (unlikely(err))
 134                 return err;
 135
 136         skb_postpull_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
 137
 138         ether_addr_copy(eth_hdr(skb)->h_source, eth_key->eth_src);
 139         ether_addr_copy(eth_hdr(skb)->h_dest, eth_key->eth_dst);
 140
 141         ovs_skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
 142
 143         return 0;
 144 }
 145
 146 static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
 147                                 __be32 *addr, __be32 new_addr)
 148 {
 149         int transport_len = skb->len - skb_transport_offset(skb);
 150
 151         if (nh->protocol == IPPROTO_TCP) {
 152                 if (likely(transport_len >= sizeof(struct tcphdr)))
 153                         inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
 154                                                  *addr, new_addr, 1);
 155         } else if (nh->protocol == IPPROTO_UDP) {
 156                 if (likely(transport_len >= sizeof(struct udphdr))) {
 157                         struct udphdr *uh = udp_hdr(skb);
 158
 159                         if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 160                                 inet_proto_csum_replace4(&uh->check, skb,
 161                                                          *addr, new_addr, 1);
 162                                 if (!uh->check)
 163                                         uh->check = CSUM_MANGLED_0;
 164                         }
 165                 }
 166         }
 167
 168         csum_replace4(&nh->check, *addr, new_addr);
 169         skb_clear_hash(skb);
 170         *addr = new_addr;
 171 }
 172
 173 static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto,
 174                                  __be32 addr[4], const __be32 new_addr[4])
 175 {
 176         int transport_len = skb->len - skb_transport_offset(skb);
 177
 178         if (l4_proto == IPPROTO_TCP) {
 179                 if (likely(transport_len >= sizeof(struct tcphdr)))
 180                         inet_proto_csum_replace16(&tcp_hdr(skb)->check, skb,
 181                                                   addr, new_addr, 1);
 182         } else if (l4_proto == IPPROTO_UDP) {
 183                 if (likely(transport_len >= sizeof(struct udphdr))) {
 184                         struct udphdr *uh = udp_hdr(skb);
 185
 186                         if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 187                                 inet_proto_csum_replace16(&uh->check, skb,
 188                                                           addr, new_addr, 1);
 189                                 if (!uh->check)
 190                                         uh->check = CSUM_MANGLED_0;
 191                         }
 192                 }
 193         }
 194 }
 195
 196 static void set_ipv6_addr(struct sk_buff *skb, u8 l4_proto,
 197                           __be32 addr[4], const __be32 new_addr[4],
 198                           bool recalculate_csum)
 199 {
 200         if (recalculate_csum)
 201                 update_ipv6_checksum(skb, l4_proto, addr, new_addr);
 202
 203         skb_clear_hash(skb);
 204         memcpy(addr, new_addr, sizeof(__be32[4]));
 205 }
 206
 207 static void set_ipv6_tc(struct ipv6hdr *nh, u8 tc)
 208 {
 209         nh->priority = tc >> 4;
 210         nh->flow_lbl[0] = (nh->flow_lbl[0] & 0x0F) | ((tc & 0x0F) << 4);
 211 }
 212
 213 static void set_ipv6_fl(struct ipv6hdr *nh, u32 fl)
 214 {
 215         nh->flow_lbl[0] = (nh->flow_lbl[0] & 0xF0) | (fl & 0x000F0000) >> 16;
 216         nh->flow_lbl[1] = (fl & 0x0000FF00) >> 8;
 217         nh->flow_lbl[2] = fl & 0x000000FF;
 218 }
 219
 220 static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
 221 {
 222         csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
 223         nh->ttl = new_ttl;
 224 }
 225
 226 static int set_ipv4(struct sk_buff *skb, const struct ovs_key_ipv4 *ipv4_key)
 227 {
 228         struct iphdr *nh;
 229         int err;
 230
 231         err = make_writable(skb, skb_network_offset(skb) +
 232                                  sizeof(struct iphdr));
 233         if (unlikely(err))
 234                 return err;
 235
 236         nh = ip_hdr(skb);
 237
 238         if (ipv4_key->ipv4_src != nh->saddr)
 239                 set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
 240
 241         if (ipv4_key->ipv4_dst != nh->daddr)
 242                 set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
 243
 244         if (ipv4_key->ipv4_tos != nh->tos)
 245                 ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
 246
 247         if (ipv4_key->ipv4_ttl != nh->ttl)
 248                 set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
 249
 250         return 0;
 251 }
 252
 253 static int set_ipv6(struct sk_buff *skb, const struct ovs_key_ipv6 *ipv6_key)
 254 {
 255         struct ipv6hdr *nh;
 256         int err;
 257         __be32 *saddr;
 258         __be32 *daddr;
 259
 260         err = make_writable(skb, skb_network_offset(skb) +
 261                             sizeof(struct ipv6hdr));
 262         if (unlikely(err))
 263                 return err;
 264
 265         nh = ipv6_hdr(skb);
 266         saddr = (__be32 *)&nh->saddr;
 267         daddr = (__be32 *)&nh->daddr;
 268
 269         if (memcmp(ipv6_key->ipv6_src, saddr, sizeof(ipv6_key->ipv6_src)))
 270                 set_ipv6_addr(skb, ipv6_key->ipv6_proto, saddr,
 271                               ipv6_key->ipv6_src, true);
 272
 273         if (memcmp(ipv6_key->ipv6_dst, daddr, sizeof(ipv6_key->ipv6_dst))) {
 274                 unsigned int offset = 0;
 275                 int flags = OVS_IP6T_FH_F_SKIP_RH;
 276                 bool recalc_csum = true;
 277
 278                 if (ipv6_ext_hdr(nh->nexthdr))
 279                         recalc_csum = ipv6_find_hdr(skb, &offset,
 280                                                     NEXTHDR_ROUTING, NULL,
 281                                                     &flags) != NEXTHDR_ROUTING;
 282
 283                 set_ipv6_addr(skb, ipv6_key->ipv6_proto, daddr,
 284                               ipv6_key->ipv6_dst, recalc_csum);
 285         }
 286
 287         set_ipv6_tc(nh, ipv6_key->ipv6_tclass);
 288         set_ipv6_fl(nh, ntohl(ipv6_key->ipv6_label));
 289         nh->hop_limit = ipv6_key->ipv6_hlimit;
 290
 291         return 0;
 292 }
 293
 294 /* Must follow make_writable() since that can move the skb data. */
 295 static void set_tp_port(struct sk_buff *skb, __be16 *port,
 296                          __be16 new_port, __sum16 *check)
 297 {
 298         inet_proto_csum_replace2(check, skb, *port, new_port, 0);
 299         *port = new_port;
 300         skb_clear_hash(skb);
 301 }
 302
 303 static void set_udp_port(struct sk_buff *skb, __be16 *port, __be16 new_port)
 304 {
 305         struct udphdr *uh = udp_hdr(skb);
 306
 307         if (uh->check && skb->ip_summed != CHECKSUM_PARTIAL) {
 308                 set_tp_port(skb, port, new_port, &uh->check);
 309
 310                 if (!uh->check)
 311                         uh->check = CSUM_MANGLED_0;
 312         } else {
 313                 *port = new_port;
 314                 skb_clear_hash(skb);
 315         }
 316 }
 317
 318 static int set_udp(struct sk_buff *skb, const struct ovs_key_udp *udp_port_key)
 319 {
 320         struct udphdr *uh;
 321         int err;
 322
 323         err = make_writable(skb, skb_transport_offset(skb) +
 324                                  sizeof(struct udphdr));
 325         if (unlikely(err))
 326                 return err;
 327
 328         uh = udp_hdr(skb);
 329         if (udp_port_key->udp_src != uh->source)
 330                 set_udp_port(skb, &uh->source, udp_port_key->udp_src);
 331
 332         if (udp_port_key->udp_dst != uh->dest)
 333                 set_udp_port(skb, &uh->dest, udp_port_key->udp_dst);
 334
 335         return 0;
 336 }
 337
 338 static int set_tcp(struct sk_buff *skb, const struct ovs_key_tcp *tcp_port_key)
 339 {
 340         struct tcphdr *th;
 341         int err;
 342
 343         err = make_writable(skb, skb_transport_offset(skb) +
 344                                  sizeof(struct tcphdr));
 345         if (unlikely(err))
 346                 return err;
 347
 348         th = tcp_hdr(skb);
 349         if (tcp_port_key->tcp_src != th->source)
 350                 set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
 351
 352         if (tcp_port_key->tcp_dst != th->dest)
 353                 set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
 354
 355         return 0;
 356 }
 357
 358 static int set_sctp(struct sk_buff *skb,
 359                      const struct ovs_key_sctp *sctp_port_key)
 360 {
 361         struct sctphdr *sh;
 362         int err;
 363         unsigned int sctphoff = skb_transport_offset(skb);
 364
 365         err = make_writable(skb, sctphoff + sizeof(struct sctphdr));
 366         if (unlikely(err))
 367                 return err;
 368
 369         sh = sctp_hdr(skb);
 370         if (sctp_port_key->sctp_src != sh->source ||
 371             sctp_port_key->sctp_dst != sh->dest) {
 372                 __le32 old_correct_csum, new_csum, old_csum;
 373
 374                 old_csum = sh->checksum;
 375                 old_correct_csum = sctp_compute_cksum(skb, sctphoff);
 376
 377                 sh->source = sctp_port_key->sctp_src;
 378                 sh->dest = sctp_port_key->sctp_dst;
 379
 380                 new_csum = sctp_compute_cksum(skb, sctphoff);
 381
 382                 /* Carry any checksum errors through. */
 383                 sh->checksum = old_csum ^ old_correct_csum ^ new_csum;
 384
 385                 skb_clear_hash(skb);
 386         }
 387
 388         return 0;
 389 }
 390
 391 static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 392 {
 393         struct vport *vport;
 394
 395         if (unlikely(!skb))
 396                 return -ENOMEM;
 397
 398         vport = ovs_vport_rcu(dp, out_port);
 399         if (unlikely(!vport)) {
 400                 kfree_skb(skb);
 401                 return -ENODEV;
 402         }
 403
 404         ovs_vport_send(vport, skb);
 405         return 0;
 406 }
 407
 408 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 409                             const struct nlattr *attr)
 410 {
 411         struct dp_upcall_info upcall;
 412         const struct nlattr *a;
 413         int rem;
 414
 415         BUG_ON(!OVS_CB(skb)->pkt_key);
 416
 417         upcall.cmd = OVS_PACKET_CMD_ACTION;
 418         upcall.key = OVS_CB(skb)->pkt_key;
 419         upcall.userdata = NULL;
 420         upcall.portid = 0;
 421
 422         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 423                  a = nla_next(a, &rem)) {
 424                 switch (nla_type(a)) {
 425                 case OVS_USERSPACE_ATTR_USERDATA:
 426                         upcall.userdata = a;
 427                         break;
 428
 429                 case OVS_USERSPACE_ATTR_PID:
 430                         upcall.portid = nla_get_u32(a);
 431                         break;
 432                 }
 433         }
 434
 435         return ovs_dp_upcall(dp, skb, &upcall);
 436 }
 437
 438 static int sample(struct datapath *dp, struct sk_buff *skb,
 439                   const struct nlattr *attr)
 440 {
 441         const struct nlattr *acts_list = NULL;
 442         const struct nlattr *a;
 443         int rem;
 444
 445         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 446                  a = nla_next(a, &rem)) {
 447                 switch (nla_type(a)) {
 448                 case OVS_SAMPLE_ATTR_PROBABILITY:
 449                         if (prandom_u32() >= nla_get_u32(a))
 450                                 return 0;
 451                         break;
 452
 453                 case OVS_SAMPLE_ATTR_ACTIONS:
 454                         acts_list = a;
 455                         break;
 456                 }
 457         }
 458
 459         return do_execute_actions(dp, skb, nla_data(acts_list),
 460                                   nla_len(acts_list), true);
 461 }
 462
 463 static void execute_hash(struct sk_buff *skb, const struct nlattr *attr)
 464 {
 465         struct sw_flow_key *key = OVS_CB(skb)->pkt_key;
 466         struct ovs_action_hash *hash_act = nla_data(attr);
 467         u32 hash = 0;
 468
 469         /* OVS_HASH_ALG_L4 is the only possible hash algorithm.  */
 470         hash = skb_get_hash(skb);
 471         hash = jhash_1word(hash, hash_act->hash_basis);
 472         if (!hash)
 473                 hash = 0x1;
 474
 475         key->ovs_flow_hash = hash;
 476 }
 477
 478 static int execute_set_action(struct sk_buff *skb,
 479                                  const struct nlattr *nested_attr)
 480 {
 481         int err = 0;
 482
 483         switch (nla_type(nested_attr)) {
 484         case OVS_KEY_ATTR_PRIORITY:
 485                 skb->priority = nla_get_u32(nested_attr);
 486                 break;
 487
 488         case OVS_KEY_ATTR_SKB_MARK:
 489                 skb->mark = nla_get_u32(nested_attr);
 490                 break;
 491
 492         case OVS_KEY_ATTR_IPV4_TUNNEL:
 493                 OVS_CB(skb)->tun_key = nla_data(nested_attr);
 494                 break;
 495
 496         case OVS_KEY_ATTR_ETHERNET:
 497                 err = set_eth_addr(skb, nla_data(nested_attr));
 498                 break;
 499
 500         case OVS_KEY_ATTR_IPV4:
 501                 err = set_ipv4(skb, nla_data(nested_attr));
 502                 break;
 503
 504         case OVS_KEY_ATTR_IPV6:
 505                 err = set_ipv6(skb, nla_data(nested_attr));
 506                 break;
 507
 508         case OVS_KEY_ATTR_TCP:
 509                 err = set_tcp(skb, nla_data(nested_attr));
 510                 break;
 511
 512         case OVS_KEY_ATTR_UDP:
 513                 err = set_udp(skb, nla_data(nested_attr));
 514                 break;
 515
 516         case OVS_KEY_ATTR_SCTP:
 517                 err = set_sctp(skb, nla_data(nested_attr));
 518                 break;
 519         }
 520
 521         return err;
 522 }
 523
 524 static int execute_recirc(struct datapath *dp, struct sk_buff *skb,
 525                                  const struct nlattr *a)
 526 {
 527         struct sw_flow_key recirc_key;
 528         const struct vport *p = OVS_CB(skb)->input_vport;
 529         uint32_t hash = OVS_CB(skb)->pkt_key->ovs_flow_hash;
 530         int err;
 531
 532         err = ovs_flow_extract(skb, p->port_no, &recirc_key);
 533         if (err)
 534                 return err;
 535
 536         recirc_key.ovs_flow_hash = hash;
 537         recirc_key.recirc_id = nla_get_u32(a);
 538
 539         ovs_dp_process_packet_with_key(skb, &recirc_key, true);
 540
 541         return 0;
 542 }
 543
 544 /* Execute a list of actions against 'skb'. */
 545 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 546                         const struct nlattr *attr, int len, bool keep_skb)
 547 {
 548         /* Every output action needs a separate clone of 'skb', but the common
 549          * case is just a single output action, so that doing a clone and
 550          * then freeing the original skbuff is wasteful.  So the following code
 551          * is slightly obscure just to avoid that. */
 552         int prev_port = -1;
 553         const struct nlattr *a;
 554         int rem;
 555
 556         for (a = attr, rem = len; rem > 0;
 557              a = nla_next(a, &rem)) {
 558                 int err = 0;
 559
 560                 if (prev_port != -1) {
 561                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 562                         prev_port = -1;
 563                 }
 564
 565                 switch (nla_type(a)) {
 566                 case OVS_ACTION_ATTR_OUTPUT:
 567                         prev_port = nla_get_u32(a);
 568                         break;
 569
 570                 case OVS_ACTION_ATTR_USERSPACE:
 571                         output_userspace(dp, skb, a);
 572                         break;
 573
 574                 case OVS_ACTION_ATTR_HASH:
 575                         execute_hash(skb, a);
 576                         break;
 577
 578                 case OVS_ACTION_ATTR_PUSH_VLAN:
 579                         err = push_vlan(skb, nla_data(a));
 580                         if (unlikely(err)) /* skb already freed. */
 581                                 return err;
 582                         break;
 583
 584                 case OVS_ACTION_ATTR_POP_VLAN:
 585                         err = pop_vlan(skb);
 586                         break;
 587
 588                 case OVS_ACTION_ATTR_RECIRC: {
 589                         struct sk_buff *recirc_skb;
 590                         const bool last_action = (a->nla_len == rem);
 591
 592                         if (!last_action || keep_skb)
 593                                 recirc_skb = skb_clone(skb, GFP_ATOMIC);
 594                         else
 595                                 recirc_skb = skb;
 596
 597                         err = execute_recirc(dp, recirc_skb, a);
 598
 599                         if (last_action || err)
 600                                 return err;
 601
 602                         break;
 603                 }
 604
 605                 case OVS_ACTION_ATTR_SET:
 606                         err = execute_set_action(skb, nla_data(a));
 607                         break;
 608
 609                 case OVS_ACTION_ATTR_SAMPLE:
 610                         err = sample(dp, skb, a);
 611                         if (unlikely(err)) /* skb already freed. */
 612                                 return err;
 613                         break;
 614                 }
 615
 616                 if (unlikely(err)) {
 617                         kfree_skb(skb);
 618                         return err;
 619                 }
 620         }
 621
 622         if (prev_port != -1) {
 623                 if (keep_skb)
 624                         skb = skb_clone(skb, GFP_ATOMIC);
 625
 626                 do_output(dp, skb, prev_port);
 627         } else if (!keep_skb)
 628                 consume_skb(skb);
 629
 630         return 0;
 631 }
 632
 633 /* We limit the number of times that we pass into execute_actions()
 634  * to avoid blowing out the stack in the event that we have a loop.
 635  *
 636  * Each loop adds some (estimated) cost to the kernel stack.
 637  * The loop terminates when the max cost is exceeded.
 638  * */
 639 #define RECIRC_STACK_COST 1
 640 #define DEFAULT_STACK_COST 4
 641 /* Allow up to 4 regular services, and up to 3 recirculations */
 642 #define MAX_STACK_COST (DEFAULT_STACK_COST * 4 + RECIRC_STACK_COST * 3)
 643
 644 struct loop_counter {
 645         u8 stack_cost;          /* loop stack cost. */
 646         bool looping;           /* Loop detected? */
 647 };
 648
 649 static DEFINE_PER_CPU(struct loop_counter, loop_counters);
 650
 651 static int loop_suppress(struct datapath *dp, struct sw_flow_actions *actions)
 652 {
 653         if (net_ratelimit())
 654                 pr_warn("%s: flow loop detected, dropping\n",
 655                                 ovs_dp_name(dp));
 656         actions->actions_len = 0;
 657         return -ELOOP;
 658 }
 659
 660 /* Execute a list of actions against 'skb'. */
 661 int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb, bool recirc)
 662 {
 663         struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 664         const u8 stack_cost = recirc ? RECIRC_STACK_COST : DEFAULT_STACK_COST;
 665         struct loop_counter *loop;
 666         int error;
 667
 668         /* Check whether we've looped too much. */
 669         loop = &__get_cpu_var(loop_counters);
 670         loop->stack_cost += stack_cost;
 671         if (unlikely(loop->stack_cost > MAX_STACK_COST))
 672                 loop->looping = true;
 673         if (unlikely(loop->looping)) {
 674                 error = loop_suppress(dp, acts);
 675                 kfree_skb(skb);
 676                 goto out_loop;
 677         }
 678
 679         OVS_CB(skb)->tun_key = NULL;
 680         error = do_execute_actions(dp, skb, acts->actions,
 681                                          acts->actions_len, false);
 682
 683         /* Check whether sub-actions looped too much. */
 684         if (unlikely(loop->looping))
 685                 error = loop_suppress(dp, acts);
 686
 687 out_loop:
 688         /* Decrement loop stack cost. */
 689         loop->stack_cost -= stack_cost;
 690         if (!loop->stack_cost)
 691                 loop->looping = false;
 692
 693         return error;
 694 }