datapath/actions.c

   1 /*
   2  * Distributed under the terms of the GNU GPL version 2.
   3  * Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
   4  *
   5  * Significant portions of this file may be copied from parts of the Linux
   6  * kernel, by Linus Torvalds and others.
   7  */
   8
   9 /* Functions for executing flow actions. */
  10
  11 #include <linux/skbuff.h>
  12 #include <linux/in.h>
  13 #include <linux/ip.h>
  14 #include <linux/tcp.h>
  15 #include <linux/udp.h>
  16 #include <linux/in6.h>
  17 #include <linux/if_vlan.h>
  18 #include <net/inet_ecn.h>
  19 #include <net/ip.h>
  20 #include <net/checksum.h>
  21
  22 #include "actions.h"
  23 #include "datapath.h"
  24 #include "openvswitch/datapath-protocol.h"
  25 #include "vport.h"
  26
  27 static struct sk_buff *
  28 make_writable(struct sk_buff *skb, unsigned min_headroom, gfp_t gfp)
  29 {
  30         if (skb_shared(skb) || skb_cloned(skb)) {
  31                 struct sk_buff *nskb;
  32                 unsigned headroom = max(min_headroom, skb_headroom(skb));
  33
  34                 nskb = skb_copy_expand(skb, headroom, skb_tailroom(skb), gfp);
  35                 if (nskb) {
  36                         set_skb_csum_bits(skb, nskb);
  37                         kfree_skb(skb);
  38                         return nskb;
  39                 }
  40         } else {
  41                 unsigned int hdr_len = (skb_transport_offset(skb)
  42                                         + sizeof(struct tcphdr));
  43                 if (pskb_may_pull(skb, min(hdr_len, skb->len)))
  44                         return skb;
  45         }
  46         kfree_skb(skb);
  47         return NULL;
  48 }
  49
  50 static void set_tunnel(struct sk_buff *skb, struct odp_flow_key *key,
  51                        __be32 tun_id)
  52 {
  53         OVS_CB(skb)->tun_id = key->tun_id = tun_id;
  54 }
  55
  56 static struct sk_buff *
  57 vlan_pull_tag(struct sk_buff *skb)
  58 {
  59         struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
  60         struct ethhdr *eh;
  61
  62         /* Verify we were given a vlan packet */
  63         if (vh->h_vlan_proto != htons(ETH_P_8021Q))
  64                 return skb;
  65
  66         if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE)
  67                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  68                                         + ETH_HLEN, VLAN_HLEN, 0));
  69
  70         memmove(skb->data + VLAN_HLEN, skb->data, 2 * VLAN_ETH_ALEN);
  71
  72         eh = (struct ethhdr *)skb_pull(skb, VLAN_HLEN);
  73
  74         skb->protocol = eh->h_proto;
  75         skb->mac_header += VLAN_HLEN;
  76
  77         return skb;
  78 }
  79
  80
  81 static struct sk_buff *
  82 modify_vlan_tci(struct datapath *dp, struct sk_buff *skb,
  83                 struct odp_flow_key *key, const union odp_action *a,
  84                 int n_actions, gfp_t gfp)
  85 {
  86         u16 tci, mask;
  87
  88         if (a->type == ODPAT_SET_VLAN_VID) {
  89                 tci = ntohs(a->vlan_vid.vlan_vid);
  90                 mask = VLAN_VID_MASK;
  91                 key->dl_vlan = a->vlan_vid.vlan_vid;
  92         } else {
  93                 tci = a->vlan_pcp.vlan_pcp << VLAN_PCP_SHIFT;
  94                 mask = VLAN_PCP_MASK;
  95                 key->dl_vlan_pcp = a->vlan_pcp.vlan_pcp;
  96         }
  97
  98         skb = make_writable(skb, VLAN_HLEN, gfp);
  99         if (!skb)
 100                 return ERR_PTR(-ENOMEM);
 101
 102         if (skb->protocol == htons(ETH_P_8021Q)) {
 103                 /* Modify vlan id, but maintain other TCI values */
 104                 struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
 105                 __be16 old_tci = vh->h_vlan_TCI;
 106
 107                 vh->h_vlan_TCI = htons((ntohs(vh->h_vlan_TCI) & ~mask) | tci);
 108
 109                 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE) {
 110                         __be16 diff[] = { ~old_tci, vh->h_vlan_TCI };
 111
 112                         skb->csum = ~csum_partial((char *)diff, sizeof(diff),
 113                                                 ~skb->csum);
 114                 }
 115         } else {
 116                 /* Add vlan header */
 117
 118                 /* Set up checksumming pointers for checksum-deferred packets
 119                  * on Xen.  Otherwise, dev_queue_xmit() will try to do this
 120                  * when we send the packet out on the wire, and it will fail at
 121                  * that point because skb_checksum_setup() will not look inside
 122                  * an 802.1Q header. */
 123                 vswitch_skb_checksum_setup(skb);
 124
 125                 /* GSO is not implemented for packets with an 802.1Q header, so
 126                  * we have to do segmentation before we add that header.
 127                  *
 128                  * GSO does work with hardware-accelerated VLAN tagging, but we
 129                  * can't use hardware-accelerated VLAN tagging since it
 130                  * requires the device to have a VLAN group configured (with
 131                  * e.g. vconfig(8)) and we don't do that.
 132                  *
 133                  * Having to do this here may be a performance loss, since we
 134                  * can't take advantage of TSO hardware support, although it
 135                  * does not make a measurable network performance difference
 136                  * for 1G Ethernet.  Fixing that would require patching the
 137                  * kernel (either to add GSO support to the VLAN protocol or to
 138                  * support hardware-accelerated VLAN tagging without VLAN
 139                  * groups configured). */
 140                 if (skb_is_gso(skb)) {
 141                         struct sk_buff *segs;
 142
 143                         segs = skb_gso_segment(skb, 0);
 144                         kfree_skb(skb);
 145                         if (unlikely(IS_ERR(segs)))
 146                                 return ERR_CAST(segs);
 147
 148                         do {
 149                                 struct sk_buff *nskb = segs->next;
 150                                 int err;
 151
 152                                 segs->next = NULL;
 153
 154                                 /* GSO can change the checksum type so update.*/
 155                                 compute_ip_summed(segs, true);
 156
 157                                 segs = __vlan_put_tag(segs, tci);
 158                                 err = -ENOMEM;
 159                                 if (segs) {
 160                                         struct odp_flow_key segkey = *key;
 161                                         err = execute_actions(dp, segs,
 162                                                               &segkey, a + 1,
 163                                                               n_actions - 1,
 164                                                               gfp);
 165                                 }
 166
 167                                 if (unlikely(err)) {
 168                                         while ((segs = nskb)) {
 169                                                 nskb = segs->next;
 170                                                 segs->next = NULL;
 171                                                 kfree_skb(segs);
 172                                         }
 173                                         return ERR_PTR(err);
 174                                 }
 175
 176                                 segs = nskb;
 177                         } while (segs->next);
 178
 179                         skb = segs;
 180                         compute_ip_summed(skb, true);
 181                 }
 182
 183                 /* The hardware-accelerated version of vlan_put_tag() works
 184                  * only for a device that has a VLAN group configured (with
 185                  * e.g. vconfig(8)), so call the software-only version
 186                  * __vlan_put_tag() directly instead.
 187                  */
 188                 skb = __vlan_put_tag(skb, tci);
 189                 if (!skb)
 190                         return ERR_PTR(-ENOMEM);
 191
 192                 /* GSO doesn't fix up the hardware computed checksum so this
 193                  * will only be hit in the non-GSO case. */
 194                 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE)
 195                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 196                                                 + ETH_HLEN, VLAN_HLEN, 0));
 197         }
 198
 199         return skb;
 200 }
 201
 202 static struct sk_buff *strip_vlan(struct sk_buff *skb,
 203                                   struct odp_flow_key *key, gfp_t gfp)
 204 {
 205         skb = make_writable(skb, 0, gfp);
 206         if (skb) {
 207                 vlan_pull_tag(skb);
 208                 key->dl_vlan = htons(ODP_VLAN_NONE);
 209         }
 210         return skb;
 211 }
 212
 213 static struct sk_buff *set_dl_addr(struct sk_buff *skb,
 214                                    struct odp_flow_key *key,
 215                                    const struct odp_action_dl_addr *a,
 216                                    gfp_t gfp)
 217 {
 218         skb = make_writable(skb, 0, gfp);
 219         if (skb) {
 220                 struct ethhdr *eh = eth_hdr(skb);
 221                 if (a->type == ODPAT_SET_DL_SRC) {
 222                         memcpy(eh->h_source, a->dl_addr, ETH_ALEN);
 223                         memcpy(key->dl_src, a->dl_addr, ETH_ALEN);
 224                 } else {
 225                         memcpy(eh->h_dest, a->dl_addr, ETH_ALEN);
 226                         memcpy(key->dl_dst, a->dl_addr, ETH_ALEN);
 227                 }
 228         }
 229         return skb;
 230 }
 231
 232 /* Updates 'sum', which is a field in 'skb''s data, given that a 4-byte field
 233  * covered by the sum has been changed from 'from' to 'to'.  If set,
 234  * 'pseudohdr' indicates that the field is in the TCP or UDP pseudo-header.
 235  * Based on nf_proto_csum_replace4. */
 236 static void update_csum(__sum16 *sum, struct sk_buff *skb,
 237                         __be32 from, __be32 to, int pseudohdr)
 238 {
 239         __be32 diff[] = { ~from, to };
 240
 241         if (OVS_CB(skb)->ip_summed != OVS_CSUM_PARTIAL) {
 242                 *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
 243                                 ~csum_unfold(*sum)));
 244                 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE && pseudohdr)
 245                         skb->csum = ~csum_partial((char *)diff, sizeof(diff),
 246                                                 ~skb->csum);
 247         } else if (pseudohdr)
 248                 *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
 249                                 csum_unfold(*sum)));
 250 }
 251
 252 static struct sk_buff *set_nw_addr(struct sk_buff *skb,
 253                                    struct odp_flow_key *key,
 254                                    const struct odp_action_nw_addr *a,
 255                                    gfp_t gfp)
 256 {
 257         if (key->dl_type != htons(ETH_P_IP))
 258                 return skb;
 259
 260         skb = make_writable(skb, 0, gfp);
 261         if (skb) {
 262                 struct iphdr *nh = ip_hdr(skb);
 263                 u32 *f = a->type == ODPAT_SET_NW_SRC ? &nh->saddr : &nh->daddr;
 264                 u32 old = *f;
 265                 u32 new = a->nw_addr;
 266
 267                 if (key->nw_proto == IPPROTO_TCP) {
 268                         struct tcphdr *th = tcp_hdr(skb);
 269                         update_csum(&th->check, skb, old, new, 1);
 270                 } else if (key->nw_proto == IPPROTO_UDP) {
 271                         struct udphdr *th = udp_hdr(skb);
 272                         update_csum(&th->check, skb, old, new, 1);
 273                 }
 274                 update_csum(&nh->check, skb, old, new, 0);
 275                 *f = new;
 276
 277                 if (a->type == ODPAT_SET_NW_SRC)
 278                         key->nw_src = a->nw_addr;
 279                 else
 280                         key->nw_dst = a->nw_addr;
 281         }
 282         return skb;
 283 }
 284
 285 static struct sk_buff *set_nw_tos(struct sk_buff *skb,
 286                                    struct odp_flow_key *key,
 287                                    const struct odp_action_nw_tos *a,
 288                                    gfp_t gfp)
 289 {
 290         if (key->dl_type != htons(ETH_P_IP))
 291                 return skb;
 292
 293         skb = make_writable(skb, 0, gfp);
 294         if (skb) {
 295                 struct iphdr *nh = ip_hdr(skb);
 296                 u8 *f = &nh->tos;
 297                 u8 old = *f;
 298                 u8 new;
 299
 300                 /* Set the DSCP bits and preserve the ECN bits. */
 301                 new = a->nw_tos | (nh->tos & INET_ECN_MASK);
 302                 update_csum(&nh->check, skb, htons((uint16_t)old),
 303                                 htons((uint16_t)new), 0);
 304                 *f = new;
 305                 key->nw_tos = a->nw_tos;
 306         }
 307         return skb;
 308 }
 309
 310 static struct sk_buff *
 311 set_tp_port(struct sk_buff *skb, struct odp_flow_key *key,
 312             const struct odp_action_tp_port *a,
 313             gfp_t gfp)
 314 {
 315         int check_ofs;
 316
 317         if (key->dl_type != htons(ETH_P_IP))
 318                 return skb;
 319
 320         if (key->nw_proto == IPPROTO_TCP)
 321                 check_ofs = offsetof(struct tcphdr, check);
 322         else if (key->nw_proto == IPPROTO_UDP)
 323                 check_ofs = offsetof(struct udphdr, check);
 324         else
 325                 return skb;
 326
 327         skb = make_writable(skb, 0, gfp);
 328         if (skb) {
 329                 struct udphdr *th = udp_hdr(skb);
 330                 u16 *f = a->type == ODPAT_SET_TP_SRC ? &th->source : &th->dest;
 331                 u16 old = *f;
 332                 u16 new = a->tp_port;
 333                 update_csum((u16*)(skb_transport_header(skb) + check_ofs),
 334                                 skb, old, new, 0);
 335                 *f = new;
 336                 if (a->type == ODPAT_SET_TP_SRC)
 337                         key->tp_src = a->tp_port;
 338                 else
 339                         key->tp_dst = a->tp_port;
 340         }
 341         return skb;
 342 }
 343
 344 static inline unsigned packet_length(const struct sk_buff *skb)
 345 {
 346         unsigned length = skb->len - ETH_HLEN;
 347         if (skb->protocol == htons(ETH_P_8021Q))
 348                 length -= VLAN_HLEN;
 349         return length;
 350 }
 351
 352 static void
 353 do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 354 {
 355         struct dp_port *p;
 356         int mtu;
 357
 358         if (!skb)
 359                 goto error;
 360
 361         p = rcu_dereference(dp->ports[out_port]);
 362         if (!p)
 363                 goto error;
 364
 365         mtu = vport_get_mtu(p->vport);
 366         if (packet_length(skb) > mtu && !skb_is_gso(skb)) {
 367                 printk(KERN_WARNING "%s: dropped over-mtu packet: %d > %d\n",
 368                        dp_name(dp), packet_length(skb), mtu);
 369                 goto error;
 370         }
 371
 372         vport_send(p->vport, skb);
 373         return;
 374
 375 error:
 376         kfree_skb(skb);
 377 }
 378
 379 /* Never consumes 'skb'.  Returns a port that 'skb' should be sent to, -1 if
 380  * none.  */
 381 static int output_group(struct datapath *dp, __u16 group,
 382                         struct sk_buff *skb, gfp_t gfp)
 383 {
 384         struct dp_port_group *g = rcu_dereference(dp->groups[group]);
 385         int prev_port = -1;
 386         int i;
 387
 388         if (!g)
 389                 return -1;
 390         for (i = 0; i < g->n_ports; i++) {
 391                 struct dp_port *p = rcu_dereference(dp->ports[g->ports[i]]);
 392                 if (!p || OVS_CB(skb)->dp_port == p)
 393                         continue;
 394                 if (prev_port != -1) {
 395                         struct sk_buff *clone = skb_clone(skb, gfp);
 396                         if (!clone)
 397                                 return -1;
 398                         do_output(dp, clone, prev_port);
 399                 }
 400                 prev_port = p->port_no;
 401         }
 402         return prev_port;
 403 }
 404
 405 static int
 406 output_control(struct datapath *dp, struct sk_buff *skb, u32 arg, gfp_t gfp)
 407 {
 408         skb = skb_clone(skb, gfp);
 409         if (!skb)
 410                 return -ENOMEM;
 411         return dp_output_control(dp, skb, _ODPL_ACTION_NR, arg);
 412 }
 413
 414 /* Send a copy of this packet up to the sFlow agent, along with extra
 415  * information about what happened to it. */
 416 static void sflow_sample(struct datapath *dp, struct sk_buff *skb,
 417                          const union odp_action *a, int n_actions,
 418                          gfp_t gfp, struct dp_port *dp_port)
 419 {
 420         struct odp_sflow_sample_header *hdr;
 421         unsigned int actlen = n_actions * sizeof(union odp_action);
 422         unsigned int hdrlen = sizeof(struct odp_sflow_sample_header);
 423         struct sk_buff *nskb;
 424
 425         nskb = skb_copy_expand(skb, actlen + hdrlen, 0, gfp);
 426         if (!nskb)
 427                 return;
 428
 429         memcpy(__skb_push(nskb, actlen), a, actlen);
 430         hdr = (struct odp_sflow_sample_header*)__skb_push(nskb, hdrlen);
 431         hdr->n_actions = n_actions;
 432         hdr->sample_pool = atomic_read(&dp_port->sflow_pool);
 433         dp_output_control(dp, nskb, _ODPL_SFLOW_NR, 0);
 434 }
 435
 436 /* Execute a list of actions against 'skb'. */
 437 int execute_actions(struct datapath *dp, struct sk_buff *skb,
 438                     struct odp_flow_key *key,
 439                     const union odp_action *a, int n_actions,
 440                     gfp_t gfp)
 441 {
 442         /* Every output action needs a separate clone of 'skb', but the common
 443          * case is just a single output action, so that doing a clone and
 444          * then freeing the original skbuff is wasteful.  So the following code
 445          * is slightly obscure just to avoid that. */
 446         int prev_port = -1;
 447         u32 priority = skb->priority;
 448         int err;
 449
 450         if (dp->sflow_probability) {
 451                 struct dp_port *p = OVS_CB(skb)->dp_port;
 452                 if (p) {
 453                         atomic_inc(&p->sflow_pool);
 454                         if (dp->sflow_probability == UINT_MAX ||
 455                             net_random() < dp->sflow_probability)
 456                                 sflow_sample(dp, skb, a, n_actions, gfp, p);
 457                 }
 458         }
 459
 460         OVS_CB(skb)->tun_id = 0;
 461
 462         for (; n_actions > 0; a++, n_actions--) {
 463                 WARN_ON_ONCE(skb_shared(skb));
 464                 if (prev_port != -1) {
 465                         do_output(dp, skb_clone(skb, gfp), prev_port);
 466                         prev_port = -1;
 467                 }
 468
 469                 switch (a->type) {
 470                 case ODPAT_OUTPUT:
 471                         prev_port = a->output.port;
 472                         break;
 473
 474                 case ODPAT_OUTPUT_GROUP:
 475                         prev_port = output_group(dp, a->output_group.group,
 476                                                  skb, gfp);
 477                         break;
 478
 479                 case ODPAT_CONTROLLER:
 480                         err = output_control(dp, skb, a->controller.arg, gfp);
 481                         if (err) {
 482                                 kfree_skb(skb);
 483                                 return err;
 484                         }
 485                         break;
 486
 487                 case ODPAT_SET_TUNNEL:
 488                         set_tunnel(skb, key, a->tunnel.tun_id);
 489                         break;
 490
 491                 case ODPAT_SET_VLAN_VID:
 492                 case ODPAT_SET_VLAN_PCP:
 493                         skb = modify_vlan_tci(dp, skb, key, a, n_actions, gfp);
 494                         if (IS_ERR(skb))
 495                                 return PTR_ERR(skb);
 496                         break;
 497
 498                 case ODPAT_STRIP_VLAN:
 499                         skb = strip_vlan(skb, key, gfp);
 500                         break;
 501
 502                 case ODPAT_SET_DL_SRC:
 503                 case ODPAT_SET_DL_DST:
 504                         skb = set_dl_addr(skb, key, &a->dl_addr, gfp);
 505                         break;
 506
 507                 case ODPAT_SET_NW_SRC:
 508                 case ODPAT_SET_NW_DST:
 509                         skb = set_nw_addr(skb, key, &a->nw_addr, gfp);
 510                         break;
 511
 512                 case ODPAT_SET_NW_TOS:
 513                         skb = set_nw_tos(skb, key, &a->nw_tos, gfp);
 514                         break;
 515
 516                 case ODPAT_SET_TP_SRC:
 517                 case ODPAT_SET_TP_DST:
 518                         skb = set_tp_port(skb, key, &a->tp_port, gfp);
 519                         break;
 520
 521                 case ODPAT_SET_PRIORITY:
 522                         skb->priority = a->priority.priority;
 523                         break;
 524
 525                 case ODPAT_POP_PRIORITY:
 526                         skb->priority = priority;
 527                         break;
 528                 }
 529                 if (!skb)
 530                         return -ENOMEM;
 531         }
 532         if (prev_port != -1)
 533                 do_output(dp, skb, prev_port);
 534         else
 535                 kfree_skb(skb);
 536         return 0;
 537 }