net/openvswitch/actions.c

   1 /*
   2  * Copyright (c) 2007-2013 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 "vport.h"
  39
  40 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  41                               struct sw_flow_key *key,
  42                               const struct nlattr *attr, int len);
  43
  44 static int make_writable(struct sk_buff *skb, int write_len)
  45 {
  46         if (!pskb_may_pull(skb, write_len))
  47                 return -ENOMEM;
  48
  49         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
  50                 return 0;
  51
  52         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  53 }
  54
  55 /* remove VLAN header from packet and update csum accordingly. */
  56 static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
  57 {
  58         struct vlan_hdr *vhdr;
  59         int err;
  60
  61         err = make_writable(skb, VLAN_ETH_HLEN);
  62         if (unlikely(err))
  63                 return err;
  64
  65         if (skb->ip_summed == CHECKSUM_COMPLETE)
  66                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  67                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
  68
  69         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
  70         *current_tci = vhdr->h_vlan_TCI;
  71
  72         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
  73         __skb_pull(skb, VLAN_HLEN);
  74
  75         vlan_set_encap_proto(skb, vhdr);
  76         skb->mac_header += VLAN_HLEN;
  77         if (skb_network_offset(skb) < ETH_HLEN)
  78                 skb_set_network_header(skb, ETH_HLEN);
  79         skb_reset_mac_len(skb);
  80
  81         return 0;
  82 }
  83
  84 static int pop_vlan(struct sk_buff *skb)
  85 {
  86         __be16 tci;
  87         int err;
  88
  89         if (likely(vlan_tx_tag_present(skb))) {
  90                 skb->vlan_tci = 0;
  91         } else {
  92                 if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
  93                              skb->len < VLAN_ETH_HLEN))
  94                         return 0;
  95
  96                 err = __pop_vlan_tci(skb, &tci);
  97                 if (err)
  98                         return err;
  99         }
 100         /* move next vlan tag to hw accel tag */
 101         if (likely(skb->protocol != htons(ETH_P_8021Q) ||
 102                    skb->len < VLAN_ETH_HLEN))
 103                 return 0;
 104
 105         err = __pop_vlan_tci(skb, &tci);
 106         if (unlikely(err))
 107                 return err;
 108
 109         __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), ntohs(tci));
 110         return 0;
 111 }
 112
 113 static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
 114 {
 115         if (unlikely(vlan_tx_tag_present(skb))) {
 116                 u16 current_tag;
 117
 118                 /* push down current VLAN tag */
 119                 current_tag = vlan_tx_tag_get(skb);
 120
 121                 if (!__vlan_put_tag(skb, skb->vlan_proto, current_tag))
 122                         return -ENOMEM;
 123
 124                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 125                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 126                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
 127
 128         }
 129         __vlan_hwaccel_put_tag(skb, vlan->vlan_tpid, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
 130         return 0;
 131 }
 132
 133 static int set_eth_addr(struct sk_buff *skb,
 134                         const struct ovs_key_ethernet *eth_key)
 135 {
 136         int err;
 137         err = make_writable(skb, ETH_HLEN);
 138         if (unlikely(err))
 139                 return err;
 140
 141         skb_postpull_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
 142
 143         ether_addr_copy(eth_hdr(skb)->h_source, eth_key->eth_src);
 144         ether_addr_copy(eth_hdr(skb)->h_dest, eth_key->eth_dst);
 145
 146         ovs_skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
 147
 148         return 0;
 149 }
 150
 151 static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
 152                                 __be32 *addr, __be32 new_addr)
 153 {
 154         int transport_len = skb->len - skb_transport_offset(skb);
 155
 156         if (nh->protocol == IPPROTO_TCP) {
 157                 if (likely(transport_len >= sizeof(struct tcphdr)))
 158                         inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
 159                                                  *addr, new_addr, 1);
 160         } else if (nh->protocol == IPPROTO_UDP) {
 161                 if (likely(transport_len >= sizeof(struct udphdr))) {
 162                         struct udphdr *uh = udp_hdr(skb);
 163
 164                         if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 165                                 inet_proto_csum_replace4(&uh->check, skb,
 166                                                          *addr, new_addr, 1);
 167                                 if (!uh->check)
 168                                         uh->check = CSUM_MANGLED_0;
 169                         }
 170                 }
 171         }
 172
 173         csum_replace4(&nh->check, *addr, new_addr);
 174         skb_clear_hash(skb);
 175         *addr = new_addr;
 176 }
 177
 178 static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto,
 179                                  __be32 addr[4], const __be32 new_addr[4])
 180 {
 181         int transport_len = skb->len - skb_transport_offset(skb);
 182
 183         if (l4_proto == IPPROTO_TCP) {
 184                 if (likely(transport_len >= sizeof(struct tcphdr)))
 185                         inet_proto_csum_replace16(&tcp_hdr(skb)->check, skb,
 186                                                   addr, new_addr, 1);
 187         } else if (l4_proto == IPPROTO_UDP) {
 188                 if (likely(transport_len >= sizeof(struct udphdr))) {
 189                         struct udphdr *uh = udp_hdr(skb);
 190
 191                         if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 192                                 inet_proto_csum_replace16(&uh->check, skb,
 193                                                           addr, new_addr, 1);
 194                                 if (!uh->check)
 195                                         uh->check = CSUM_MANGLED_0;
 196                         }
 197                 }
 198         }
 199 }
 200
 201 static void set_ipv6_addr(struct sk_buff *skb, u8 l4_proto,
 202                           __be32 addr[4], const __be32 new_addr[4],
 203                           bool recalculate_csum)
 204 {
 205         if (recalculate_csum)
 206                 update_ipv6_checksum(skb, l4_proto, addr, new_addr);
 207
 208         skb_clear_hash(skb);
 209         memcpy(addr, new_addr, sizeof(__be32[4]));
 210 }
 211
 212 static void set_ipv6_tc(struct ipv6hdr *nh, u8 tc)
 213 {
 214         nh->priority = tc >> 4;
 215         nh->flow_lbl[0] = (nh->flow_lbl[0] & 0x0F) | ((tc & 0x0F) << 4);
 216 }
 217
 218 static void set_ipv6_fl(struct ipv6hdr *nh, u32 fl)
 219 {
 220         nh->flow_lbl[0] = (nh->flow_lbl[0] & 0xF0) | (fl & 0x000F0000) >> 16;
 221         nh->flow_lbl[1] = (fl & 0x0000FF00) >> 8;
 222         nh->flow_lbl[2] = fl & 0x000000FF;
 223 }
 224
 225 static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
 226 {
 227         csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
 228         nh->ttl = new_ttl;
 229 }
 230
 231 static int set_ipv4(struct sk_buff *skb, const struct ovs_key_ipv4 *ipv4_key)
 232 {
 233         struct iphdr *nh;
 234         int err;
 235
 236         err = make_writable(skb, skb_network_offset(skb) +
 237                                  sizeof(struct iphdr));
 238         if (unlikely(err))
 239                 return err;
 240
 241         nh = ip_hdr(skb);
 242
 243         if (ipv4_key->ipv4_src != nh->saddr)
 244                 set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
 245
 246         if (ipv4_key->ipv4_dst != nh->daddr)
 247                 set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
 248
 249         if (ipv4_key->ipv4_tos != nh->tos)
 250                 ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
 251
 252         if (ipv4_key->ipv4_ttl != nh->ttl)
 253                 set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
 254
 255         return 0;
 256 }
 257
 258 static int set_ipv6(struct sk_buff *skb, const struct ovs_key_ipv6 *ipv6_key)
 259 {
 260         struct ipv6hdr *nh;
 261         int err;
 262         __be32 *saddr;
 263         __be32 *daddr;
 264
 265         err = make_writable(skb, skb_network_offset(skb) +
 266                             sizeof(struct ipv6hdr));
 267         if (unlikely(err))
 268                 return err;
 269
 270         nh = ipv6_hdr(skb);
 271         saddr = (__be32 *)&nh->saddr;
 272         daddr = (__be32 *)&nh->daddr;
 273
 274         if (memcmp(ipv6_key->ipv6_src, saddr, sizeof(ipv6_key->ipv6_src)))
 275                 set_ipv6_addr(skb, ipv6_key->ipv6_proto, saddr,
 276                               ipv6_key->ipv6_src, true);
 277
 278         if (memcmp(ipv6_key->ipv6_dst, daddr, sizeof(ipv6_key->ipv6_dst))) {
 279                 unsigned int offset = 0;
 280                 int flags = IP6_FH_F_SKIP_RH;
 281                 bool recalc_csum = true;
 282
 283                 if (ipv6_ext_hdr(nh->nexthdr))
 284                         recalc_csum = ipv6_find_hdr(skb, &offset,
 285                                                     NEXTHDR_ROUTING, NULL,
 286                                                     &flags) != NEXTHDR_ROUTING;
 287
 288                 set_ipv6_addr(skb, ipv6_key->ipv6_proto, daddr,
 289                               ipv6_key->ipv6_dst, recalc_csum);
 290         }
 291
 292         set_ipv6_tc(nh, ipv6_key->ipv6_tclass);
 293         set_ipv6_fl(nh, ntohl(ipv6_key->ipv6_label));
 294         nh->hop_limit = ipv6_key->ipv6_hlimit;
 295
 296         return 0;
 297 }
 298
 299 /* Must follow make_writable() since that can move the skb data. */
 300 static void set_tp_port(struct sk_buff *skb, __be16 *port,
 301                          __be16 new_port, __sum16 *check)
 302 {
 303         inet_proto_csum_replace2(check, skb, *port, new_port, 0);
 304         *port = new_port;
 305         skb_clear_hash(skb);
 306 }
 307
 308 static void set_udp_port(struct sk_buff *skb, __be16 *port, __be16 new_port)
 309 {
 310         struct udphdr *uh = udp_hdr(skb);
 311
 312         if (uh->check && skb->ip_summed != CHECKSUM_PARTIAL) {
 313                 set_tp_port(skb, port, new_port, &uh->check);
 314
 315                 if (!uh->check)
 316                         uh->check = CSUM_MANGLED_0;
 317         } else {
 318                 *port = new_port;
 319                 skb_clear_hash(skb);
 320         }
 321 }
 322
 323 static int set_udp(struct sk_buff *skb, const struct ovs_key_udp *udp_port_key)
 324 {
 325         struct udphdr *uh;
 326         int err;
 327
 328         err = make_writable(skb, skb_transport_offset(skb) +
 329                                  sizeof(struct udphdr));
 330         if (unlikely(err))
 331                 return err;
 332
 333         uh = udp_hdr(skb);
 334         if (udp_port_key->udp_src != uh->source)
 335                 set_udp_port(skb, &uh->source, udp_port_key->udp_src);
 336
 337         if (udp_port_key->udp_dst != uh->dest)
 338                 set_udp_port(skb, &uh->dest, udp_port_key->udp_dst);
 339
 340         return 0;
 341 }
 342
 343 static int set_tcp(struct sk_buff *skb, const struct ovs_key_tcp *tcp_port_key)
 344 {
 345         struct tcphdr *th;
 346         int err;
 347
 348         err = make_writable(skb, skb_transport_offset(skb) +
 349                                  sizeof(struct tcphdr));
 350         if (unlikely(err))
 351                 return err;
 352
 353         th = tcp_hdr(skb);
 354         if (tcp_port_key->tcp_src != th->source)
 355                 set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
 356
 357         if (tcp_port_key->tcp_dst != th->dest)
 358                 set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
 359
 360         return 0;
 361 }
 362
 363 static int set_sctp(struct sk_buff *skb,
 364                      const struct ovs_key_sctp *sctp_port_key)
 365 {
 366         struct sctphdr *sh;
 367         int err;
 368         unsigned int sctphoff = skb_transport_offset(skb);
 369
 370         err = make_writable(skb, sctphoff + sizeof(struct sctphdr));
 371         if (unlikely(err))
 372                 return err;
 373
 374         sh = sctp_hdr(skb);
 375         if (sctp_port_key->sctp_src != sh->source ||
 376             sctp_port_key->sctp_dst != sh->dest) {
 377                 __le32 old_correct_csum, new_csum, old_csum;
 378
 379                 old_csum = sh->checksum;
 380                 old_correct_csum = sctp_compute_cksum(skb, sctphoff);
 381
 382                 sh->source = sctp_port_key->sctp_src;
 383                 sh->dest = sctp_port_key->sctp_dst;
 384
 385                 new_csum = sctp_compute_cksum(skb, sctphoff);
 386
 387                 /* Carry any checksum errors through. */
 388                 sh->checksum = old_csum ^ old_correct_csum ^ new_csum;
 389
 390                 skb_clear_hash(skb);
 391         }
 392
 393         return 0;
 394 }
 395
 396 static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 397 {
 398         struct vport *vport;
 399
 400         if (unlikely(!skb))
 401                 return -ENOMEM;
 402
 403         vport = ovs_vport_rcu(dp, out_port);
 404         if (unlikely(!vport)) {
 405                 kfree_skb(skb);
 406                 return -ENODEV;
 407         }
 408
 409         ovs_vport_send(vport, skb);
 410         return 0;
 411 }
 412
 413 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 414                             struct sw_flow_key *key, const struct nlattr *attr)
 415 {
 416         struct dp_upcall_info upcall;
 417         const struct nlattr *a;
 418         int rem;
 419
 420         upcall.cmd = OVS_PACKET_CMD_ACTION;
 421         upcall.key = key;
 422         upcall.userdata = NULL;
 423         upcall.portid = 0;
 424
 425         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 426                  a = nla_next(a, &rem)) {
 427                 switch (nla_type(a)) {
 428                 case OVS_USERSPACE_ATTR_USERDATA:
 429                         upcall.userdata = a;
 430                         break;
 431
 432                 case OVS_USERSPACE_ATTR_PID:
 433                         upcall.portid = nla_get_u32(a);
 434                         break;
 435                 }
 436         }
 437
 438         return ovs_dp_upcall(dp, skb, &upcall);
 439 }
 440
 441 static bool last_action(const struct nlattr *a, int rem)
 442 {
 443         return a->nla_len == rem;
 444 }
 445
 446 static int sample(struct datapath *dp, struct sk_buff *skb,
 447                   struct sw_flow_key *key, const struct nlattr *attr)
 448 {
 449         const struct nlattr *acts_list = NULL;
 450         const struct nlattr *a;
 451         struct sk_buff *sample_skb;
 452         int rem;
 453
 454         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 455                  a = nla_next(a, &rem)) {
 456                 switch (nla_type(a)) {
 457                 case OVS_SAMPLE_ATTR_PROBABILITY:
 458                         if (prandom_u32() >= nla_get_u32(a))
 459                                 return 0;
 460                         break;
 461
 462                 case OVS_SAMPLE_ATTR_ACTIONS:
 463                         acts_list = a;
 464                         break;
 465                 }
 466         }
 467
 468         rem = nla_len(acts_list);
 469         a = nla_data(acts_list);
 470
 471         /* Actions list is either empty or only contains a single user-space
 472          * action, the latter being a special case as it is the only known
 473          * usage of the sample action.
 474          * In these special cases don't clone the skb as there are no
 475          * side-effects in the nested actions.
 476          * Otherwise, clone in case the nested actions have side effects.
 477          */
 478         if (likely(rem == 0 || (nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
 479                                 last_action(a, rem)))) {
 480                 sample_skb = skb;
 481                 skb_get(skb);
 482         } else {
 483                 sample_skb = skb_clone(skb, GFP_ATOMIC);
 484                 if (!sample_skb) /* Skip sample action when out of memory. */
 485                         return 0;
 486         }
 487
 488         /* Note that do_execute_actions() never consumes skb.
 489          * In the case where skb has been cloned above it is the clone that
 490          * is consumed.  Otherwise the skb_get(skb) call prevents
 491          * consumption by do_execute_actions(). Thus, it is safe to simply
 492          * return the error code and let the caller (also
 493          * do_execute_actions()) free skb on error.
 494          */
 495         return do_execute_actions(dp, sample_skb, key, a, rem);
 496 }
 497
 498 static int execute_set_action(struct sk_buff *skb,
 499                                  const struct nlattr *nested_attr)
 500 {
 501         int err = 0;
 502
 503         switch (nla_type(nested_attr)) {
 504         case OVS_KEY_ATTR_PRIORITY:
 505                 skb->priority = nla_get_u32(nested_attr);
 506                 break;
 507
 508         case OVS_KEY_ATTR_SKB_MARK:
 509                 skb->mark = nla_get_u32(nested_attr);
 510                 break;
 511
 512         case OVS_KEY_ATTR_IPV4_TUNNEL:
 513                 OVS_CB(skb)->egress_tun_key = nla_data(nested_attr);
 514                 break;
 515
 516         case OVS_KEY_ATTR_ETHERNET:
 517                 err = set_eth_addr(skb, nla_data(nested_attr));
 518                 break;
 519
 520         case OVS_KEY_ATTR_IPV4:
 521                 err = set_ipv4(skb, nla_data(nested_attr));
 522                 break;
 523
 524         case OVS_KEY_ATTR_IPV6:
 525                 err = set_ipv6(skb, nla_data(nested_attr));
 526                 break;
 527
 528         case OVS_KEY_ATTR_TCP:
 529                 err = set_tcp(skb, nla_data(nested_attr));
 530                 break;
 531
 532         case OVS_KEY_ATTR_UDP:
 533                 err = set_udp(skb, nla_data(nested_attr));
 534                 break;
 535
 536         case OVS_KEY_ATTR_SCTP:
 537                 err = set_sctp(skb, nla_data(nested_attr));
 538                 break;
 539         }
 540
 541         return err;
 542 }
 543
 544 /* Execute a list of actions against 'skb'. */
 545 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 546                               struct sw_flow_key *key,
 547                               const struct nlattr *attr, int len)
 548 {
 549         /* Every output action needs a separate clone of 'skb', but the common
 550          * case is just a single output action, so that doing a clone and
 551          * then freeing the original skbuff is wasteful.  So the following code
 552          * is slightly obscure just to avoid that. */
 553         int prev_port = -1;
 554         const struct nlattr *a;
 555         int rem;
 556
 557         for (a = attr, rem = len; rem > 0;
 558              a = nla_next(a, &rem)) {
 559                 int err = 0;
 560
 561                 if (prev_port != -1) {
 562                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 563                         prev_port = -1;
 564                 }
 565
 566                 switch (nla_type(a)) {
 567                 case OVS_ACTION_ATTR_OUTPUT:
 568                         prev_port = nla_get_u32(a);
 569                         break;
 570
 571                 case OVS_ACTION_ATTR_USERSPACE:
 572                         output_userspace(dp, skb, key, a);
 573                         break;
 574
 575                 case OVS_ACTION_ATTR_PUSH_VLAN:
 576                         err = push_vlan(skb, nla_data(a));
 577                         if (unlikely(err)) /* skb already freed. */
 578                                 return err;
 579                         break;
 580
 581                 case OVS_ACTION_ATTR_POP_VLAN:
 582                         err = pop_vlan(skb);
 583                         break;
 584
 585                 case OVS_ACTION_ATTR_SET:
 586                         err = execute_set_action(skb, nla_data(a));
 587                         break;
 588
 589                 case OVS_ACTION_ATTR_SAMPLE:
 590                         err = sample(dp, skb, key, a);
 591                         if (unlikely(err)) /* skb already freed. */
 592                                 return err;
 593                         break;
 594                 }
 595
 596                 if (unlikely(err)) {
 597                         kfree_skb(skb);
 598                         return err;
 599                 }
 600         }
 601
 602         if (prev_port != -1)
 603                 do_output(dp, skb, prev_port);
 604         else
 605                 consume_skb(skb);
 606
 607         return 0;
 608 }
 609
 610 /* Execute a list of actions against 'skb'. */
 611 int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
 612                         struct sw_flow_key *key)
 613 {
 614         struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 615
 616         return do_execute_actions(dp, skb, key,
 617                                   acts->actions, acts->actions_len);
 618 }