datapath/actions.c

   1 /*
   2  * Copyright (c) 2007-2012 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/tcp.h>
  26 #include <linux/udp.h>
  27 #include <linux/in6.h>
  28 #include <linux/if_arp.h>
  29 #include <linux/if_vlan.h>
  30 #include <net/ip.h>
  31 #include <net/ipv6.h>
  32 #include <net/checksum.h>
  33 #include <net/dsfield.h>
  34
  35 #include "checksum.h"
  36 #include "datapath.h"
  37 #include "vlan.h"
  38 #include "vport.h"
  39
  40 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  41                               const struct nlattr *attr, int len, bool keep_skb);
  42
  43 static int make_writable(struct sk_buff *skb, int write_len)
  44 {
  45         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
  46                 return 0;
  47
  48         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  49 }
  50
  51 /* remove VLAN header from packet and update csum accordingly. */
  52 static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
  53 {
  54         struct vlan_hdr *vhdr;
  55         int err;
  56
  57         err = make_writable(skb, VLAN_ETH_HLEN);
  58         if (unlikely(err))
  59                 return err;
  60
  61         if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
  62                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  63                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
  64
  65         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
  66         *current_tci = vhdr->h_vlan_TCI;
  67
  68         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
  69         __skb_pull(skb, VLAN_HLEN);
  70
  71         vlan_set_encap_proto(skb, vhdr);
  72         skb->mac_header += VLAN_HLEN;
  73         skb_reset_mac_len(skb);
  74
  75         return 0;
  76 }
  77
  78 static int pop_vlan(struct sk_buff *skb)
  79 {
  80         __be16 tci;
  81         int err;
  82
  83         if (likely(vlan_tx_tag_present(skb))) {
  84                 vlan_set_tci(skb, 0);
  85         } else {
  86                 if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
  87                              skb->len < VLAN_ETH_HLEN))
  88                         return 0;
  89
  90                 err = __pop_vlan_tci(skb, &tci);
  91                 if (err)
  92                         return err;
  93         }
  94         /* move next vlan tag to hw accel tag */
  95         if (likely(skb->protocol != htons(ETH_P_8021Q) ||
  96                    skb->len < VLAN_ETH_HLEN))
  97                 return 0;
  98
  99         err = __pop_vlan_tci(skb, &tci);
 100         if (unlikely(err))
 101                 return err;
 102
 103         __vlan_hwaccel_put_tag(skb, ntohs(tci));
 104         return 0;
 105 }
 106
 107 static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
 108 {
 109         if (unlikely(vlan_tx_tag_present(skb))) {
 110                 u16 current_tag;
 111
 112                 /* push down current VLAN tag */
 113                 current_tag = vlan_tx_tag_get(skb);
 114
 115                 if (!__vlan_put_tag(skb, current_tag))
 116                         return -ENOMEM;
 117
 118                 if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
 119                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 120                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
 121
 122         }
 123         __vlan_hwaccel_put_tag(skb, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
 124         return 0;
 125 }
 126
 127 static int set_eth_addr(struct sk_buff *skb,
 128                         const struct ovs_key_ethernet *eth_key)
 129 {
 130         int err;
 131         err = make_writable(skb, ETH_HLEN);
 132         if (unlikely(err))
 133                 return err;
 134
 135         memcpy(eth_hdr(skb)->h_source, eth_key->eth_src, ETH_ALEN);
 136         memcpy(eth_hdr(skb)->h_dest, eth_key->eth_dst, ETH_ALEN);
 137
 138         return 0;
 139 }
 140
 141 static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
 142                                 __be32 *addr, __be32 new_addr)
 143 {
 144         int transport_len = skb->len - skb_transport_offset(skb);
 145
 146         if (nh->protocol == IPPROTO_TCP) {
 147                 if (likely(transport_len >= sizeof(struct tcphdr)))
 148                         inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
 149                                                  *addr, new_addr, 1);
 150         } else if (nh->protocol == IPPROTO_UDP) {
 151                 if (likely(transport_len >= sizeof(struct udphdr))) {
 152                         struct udphdr *uh = udp_hdr(skb);
 153
 154                         if (uh->check ||
 155                             get_ip_summed(skb) == OVS_CSUM_PARTIAL) {
 156                                 inet_proto_csum_replace4(&uh->check, skb,
 157                                                          *addr, new_addr, 1);
 158                                 if (!uh->check)
 159                                         uh->check = CSUM_MANGLED_0;
 160                         }
 161                 }
 162         }
 163
 164         csum_replace4(&nh->check, *addr, new_addr);
 165         skb_clear_rxhash(skb);
 166         *addr = new_addr;
 167 }
 168
 169 static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto,
 170                                  __be32 addr[4], const __be32 new_addr[4])
 171 {
 172         int transport_len = skb->len - skb_transport_offset(skb);
 173
 174         if (l4_proto == IPPROTO_TCP) {
 175                 if (likely(transport_len >= sizeof(struct tcphdr)))
 176                         inet_proto_csum_replace16(&tcp_hdr(skb)->check, skb,
 177                                                   addr, new_addr, 1);
 178         } else if (l4_proto == IPPROTO_UDP) {
 179                 if (likely(transport_len >= sizeof(struct udphdr))) {
 180                         struct udphdr *uh = udp_hdr(skb);
 181
 182                         if (uh->check ||
 183                             get_ip_summed(skb) == OVS_CSUM_PARTIAL) {
 184                                 inet_proto_csum_replace16(&uh->check, skb,
 185                                                           addr, new_addr, 1);
 186                                 if (!uh->check)
 187                                         uh->check = CSUM_MANGLED_0;
 188                         }
 189                 }
 190         }
 191 }
 192
 193 static void set_ipv6_addr(struct sk_buff *skb, u8 l4_proto,
 194                           __be32 addr[4], const __be32 new_addr[4],
 195                           bool recalculate_csum)
 196 {
 197         if (recalculate_csum)
 198                 update_ipv6_checksum(skb, l4_proto, addr, new_addr);
 199
 200         skb_clear_rxhash(skb);
 201         memcpy(addr, new_addr, sizeof(__be32[4]));
 202 }
 203
 204 static void set_ipv6_tc(struct ipv6hdr *nh, u8 tc)
 205 {
 206         nh->priority = tc >> 4;
 207         nh->flow_lbl[0] = (nh->flow_lbl[0] & 0x0F) | ((tc & 0x0F) << 4);
 208 }
 209
 210 static void set_ipv6_fl(struct ipv6hdr *nh, u32 fl)
 211 {
 212         nh->flow_lbl[0] = (nh->flow_lbl[0] & 0xF0) | (fl & 0x000F0000) >> 16;
 213         nh->flow_lbl[1] = (fl & 0x0000FF00) >> 8;
 214         nh->flow_lbl[2] = fl & 0x000000FF;
 215 }
 216
 217 static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
 218 {
 219         csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
 220         nh->ttl = new_ttl;
 221 }
 222
 223 static int set_ipv4(struct sk_buff *skb, const struct ovs_key_ipv4 *ipv4_key)
 224 {
 225         struct iphdr *nh;
 226         int err;
 227
 228         err = make_writable(skb, skb_network_offset(skb) +
 229                                  sizeof(struct iphdr));
 230         if (unlikely(err))
 231                 return err;
 232
 233         nh = ip_hdr(skb);
 234
 235         if (ipv4_key->ipv4_src != nh->saddr)
 236                 set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
 237
 238         if (ipv4_key->ipv4_dst != nh->daddr)
 239                 set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
 240
 241         if (ipv4_key->ipv4_tos != nh->tos)
 242                 ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
 243
 244         if (ipv4_key->ipv4_ttl != nh->ttl)
 245                 set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
 246
 247         return 0;
 248 }
 249
 250 static int set_ipv6(struct sk_buff *skb, const struct ovs_key_ipv6 *ipv6_key)
 251 {
 252         struct ipv6hdr *nh;
 253         int err;
 254         __be32 *saddr;
 255         __be32 *daddr;
 256
 257         err = make_writable(skb, skb_network_offset(skb) +
 258                             sizeof(struct ipv6hdr));
 259         if (unlikely(err))
 260                 return err;
 261
 262         nh = ipv6_hdr(skb);
 263         saddr = (__be32 *)&nh->saddr;
 264         daddr = (__be32 *)&nh->daddr;
 265
 266         if (memcmp(ipv6_key->ipv6_src, saddr, sizeof(ipv6_key->ipv6_src)))
 267                 set_ipv6_addr(skb, ipv6_key->ipv6_proto, saddr,
 268                               ipv6_key->ipv6_src, true);
 269
 270         if (memcmp(ipv6_key->ipv6_dst, daddr, sizeof(ipv6_key->ipv6_dst))) {
 271                 unsigned int offset = 0;
 272                 int flags = OVS_IP6T_FH_F_SKIP_RH;
 273                 bool recalc_csum = true;
 274
 275                 if (ipv6_ext_hdr(nh->nexthdr))
 276                         recalc_csum = ipv6_find_hdr(skb, &offset,
 277                                                     NEXTHDR_ROUTING, NULL,
 278                                                     &flags) != NEXTHDR_ROUTING;
 279
 280                 set_ipv6_addr(skb, ipv6_key->ipv6_proto, daddr,
 281                               ipv6_key->ipv6_dst, recalc_csum);
 282         }
 283
 284         set_ipv6_tc(nh, ipv6_key->ipv6_tclass);
 285         set_ipv6_fl(nh, ntohl(ipv6_key->ipv6_label));
 286         nh->hop_limit = ipv6_key->ipv6_hlimit;
 287
 288         return 0;
 289 }
 290
 291 /* Must follow make_writable() since that can move the skb data. */
 292 static void set_tp_port(struct sk_buff *skb, __be16 *port,
 293                          __be16 new_port, __sum16 *check)
 294 {
 295         inet_proto_csum_replace2(check, skb, *port, new_port, 0);
 296         *port = new_port;
 297         skb_clear_rxhash(skb);
 298 }
 299
 300 static void set_udp_port(struct sk_buff *skb, __be16 *port, __be16 new_port)
 301 {
 302         struct udphdr *uh = udp_hdr(skb);
 303
 304         if (uh->check && get_ip_summed(skb) != OVS_CSUM_PARTIAL) {
 305                 set_tp_port(skb, port, new_port, &uh->check);
 306
 307                 if (!uh->check)
 308                         uh->check = CSUM_MANGLED_0;
 309         } else {
 310                 *port = new_port;
 311                 skb_clear_rxhash(skb);
 312         }
 313 }
 314
 315 static int set_udp(struct sk_buff *skb, const struct ovs_key_udp *udp_port_key)
 316 {
 317         struct udphdr *uh;
 318         int err;
 319
 320         err = make_writable(skb, skb_transport_offset(skb) +
 321                                  sizeof(struct udphdr));
 322         if (unlikely(err))
 323                 return err;
 324
 325         uh = udp_hdr(skb);
 326         if (udp_port_key->udp_src != uh->source)
 327                 set_udp_port(skb, &uh->source, udp_port_key->udp_src);
 328
 329         if (udp_port_key->udp_dst != uh->dest)
 330                 set_udp_port(skb, &uh->dest, udp_port_key->udp_dst);
 331
 332         return 0;
 333 }
 334
 335 static int set_tcp(struct sk_buff *skb, const struct ovs_key_tcp *tcp_port_key)
 336 {
 337         struct tcphdr *th;
 338         int err;
 339
 340         err = make_writable(skb, skb_transport_offset(skb) +
 341                                  sizeof(struct tcphdr));
 342         if (unlikely(err))
 343                 return err;
 344
 345         th = tcp_hdr(skb);
 346         if (tcp_port_key->tcp_src != th->source)
 347                 set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
 348
 349         if (tcp_port_key->tcp_dst != th->dest)
 350                 set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
 351
 352         return 0;
 353 }
 354
 355 static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 356 {
 357         struct vport *vport;
 358
 359         if (unlikely(!skb))
 360                 return -ENOMEM;
 361
 362         vport = ovs_vport_rcu(dp, out_port);
 363         if (unlikely(!vport)) {
 364                 kfree_skb(skb);
 365                 return -ENODEV;
 366         }
 367
 368         ovs_vport_send(vport, skb);
 369         return 0;
 370 }
 371
 372 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 373                             const struct nlattr *attr)
 374 {
 375         struct dp_upcall_info upcall;
 376         const struct nlattr *a;
 377         int rem;
 378
 379         upcall.cmd = OVS_PACKET_CMD_ACTION;
 380         upcall.key = &OVS_CB(skb)->flow->key;
 381         upcall.userdata = NULL;
 382         upcall.portid = 0;
 383
 384         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 385                  a = nla_next(a, &rem)) {
 386                 switch (nla_type(a)) {
 387                 case OVS_USERSPACE_ATTR_USERDATA:
 388                         upcall.userdata = a;
 389                         break;
 390
 391                 case OVS_USERSPACE_ATTR_PID:
 392                         upcall.portid = nla_get_u32(a);
 393                         break;
 394                 }
 395         }
 396
 397         return ovs_dp_upcall(dp, skb, &upcall);
 398 }
 399
 400 static int sample(struct datapath *dp, struct sk_buff *skb,
 401                   const struct nlattr *attr)
 402 {
 403         const struct nlattr *acts_list = NULL;
 404         const struct nlattr *a;
 405         int rem;
 406
 407         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 408                  a = nla_next(a, &rem)) {
 409                 switch (nla_type(a)) {
 410                 case OVS_SAMPLE_ATTR_PROBABILITY:
 411                         if (net_random() >= nla_get_u32(a))
 412                                 return 0;
 413                         break;
 414
 415                 case OVS_SAMPLE_ATTR_ACTIONS:
 416                         acts_list = a;
 417                         break;
 418                 }
 419         }
 420
 421         return do_execute_actions(dp, skb, nla_data(acts_list),
 422                                   nla_len(acts_list), true);
 423 }
 424
 425 static int execute_set_action(struct sk_buff *skb,
 426                                  const struct nlattr *nested_attr)
 427 {
 428         int err = 0;
 429
 430         switch (nla_type(nested_attr)) {
 431         case OVS_KEY_ATTR_PRIORITY:
 432                 skb->priority = nla_get_u32(nested_attr);
 433                 break;
 434
 435         case OVS_KEY_ATTR_SKB_MARK:
 436                 skb_set_mark(skb, nla_get_u32(nested_attr));
 437                 break;
 438
 439         case OVS_KEY_ATTR_IPV4_TUNNEL:
 440                 OVS_CB(skb)->tun_key = nla_data(nested_attr);
 441                 break;
 442
 443         case OVS_KEY_ATTR_ETHERNET:
 444                 err = set_eth_addr(skb, nla_data(nested_attr));
 445                 break;
 446
 447         case OVS_KEY_ATTR_IPV4:
 448                 err = set_ipv4(skb, nla_data(nested_attr));
 449                 break;
 450
 451         case OVS_KEY_ATTR_IPV6:
 452                 err = set_ipv6(skb, nla_data(nested_attr));
 453                 break;
 454
 455         case OVS_KEY_ATTR_TCP:
 456                 err = set_tcp(skb, nla_data(nested_attr));
 457                 break;
 458
 459         case OVS_KEY_ATTR_UDP:
 460                 err = set_udp(skb, nla_data(nested_attr));
 461                 break;
 462         }
 463
 464         return err;
 465 }
 466
 467 /* Execute a list of actions against 'skb'. */
 468 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 469                         const struct nlattr *attr, int len, bool keep_skb)
 470 {
 471         /* Every output action needs a separate clone of 'skb', but the common
 472          * case is just a single output action, so that doing a clone and
 473          * then freeing the original skbuff is wasteful.  So the following code
 474          * is slightly obscure just to avoid that. */
 475         int prev_port = -1;
 476         const struct nlattr *a;
 477         int rem;
 478
 479         for (a = attr, rem = len; rem > 0;
 480              a = nla_next(a, &rem)) {
 481                 int err = 0;
 482
 483                 if (prev_port != -1) {
 484                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 485                         prev_port = -1;
 486                 }
 487
 488                 switch (nla_type(a)) {
 489                 case OVS_ACTION_ATTR_OUTPUT:
 490                         prev_port = nla_get_u32(a);
 491                         break;
 492
 493                 case OVS_ACTION_ATTR_USERSPACE:
 494                         output_userspace(dp, skb, a);
 495                         break;
 496
 497                 case OVS_ACTION_ATTR_PUSH_VLAN:
 498                         err = push_vlan(skb, nla_data(a));
 499                         if (unlikely(err)) /* skb already freed. */
 500                                 return err;
 501                         break;
 502
 503                 case OVS_ACTION_ATTR_POP_VLAN:
 504                         err = pop_vlan(skb);
 505                         break;
 506
 507                 case OVS_ACTION_ATTR_SET:
 508                         err = execute_set_action(skb, nla_data(a));
 509                         break;
 510
 511                 case OVS_ACTION_ATTR_SAMPLE:
 512                         err = sample(dp, skb, a);
 513                         break;
 514                 }
 515
 516                 if (unlikely(err)) {
 517                         kfree_skb(skb);
 518                         return err;
 519                 }
 520         }
 521
 522         if (prev_port != -1) {
 523                 if (keep_skb)
 524                         skb = skb_clone(skb, GFP_ATOMIC);
 525
 526                 do_output(dp, skb, prev_port);
 527         } else if (!keep_skb)
 528                 consume_skb(skb);
 529
 530         return 0;
 531 }
 532
 533 /* We limit the number of times that we pass into execute_actions()
 534  * to avoid blowing out the stack in the event that we have a loop. */
 535 #define MAX_LOOPS 4
 536
 537 struct loop_counter {
 538         u8 count;               /* Count. */
 539         bool looping;           /* Loop detected? */
 540 };
 541
 542 static DEFINE_PER_CPU(struct loop_counter, loop_counters);
 543
 544 static int loop_suppress(struct datapath *dp, struct sw_flow_actions *actions)
 545 {
 546         if (net_ratelimit())
 547                 pr_warn("%s: flow looped %d times, dropping\n",
 548                                 ovs_dp_name(dp), MAX_LOOPS);
 549         actions->actions_len = 0;
 550         return -ELOOP;
 551 }
 552
 553 /* Execute a list of actions against 'skb'. */
 554 int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb)
 555 {
 556         struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 557         struct loop_counter *loop;
 558         int error;
 559
 560         /* Check whether we've looped too much. */
 561         loop = &__get_cpu_var(loop_counters);
 562         if (unlikely(++loop->count > MAX_LOOPS))
 563                 loop->looping = true;
 564         if (unlikely(loop->looping)) {
 565                 error = loop_suppress(dp, acts);
 566                 kfree_skb(skb);
 567                 goto out_loop;
 568         }
 569
 570         OVS_CB(skb)->tun_key = NULL;
 571         error = do_execute_actions(dp, skb, acts->actions,
 572                                          acts->actions_len, false);
 573
 574         /* Check whether sub-actions looped too much. */
 575         if (unlikely(loop->looping))
 576                 error = loop_suppress(dp, acts);
 577
 578 out_loop:
 579         /* Decrement loop counter. */
 580         if (!--loop->count)
 581                 loop->looping = false;
 582
 583         return error;
 584 }