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                 int err;
 117
 118                 /* Add vlan header */
 119
 120                 /* Set up checksumming pointers for checksum-deferred packets
 121                  * on Xen.  Otherwise, dev_queue_xmit() will try to do this
 122                  * when we send the packet out on the wire, and it will fail at
 123                  * that point because skb_checksum_setup() will not look inside
 124                  * an 802.1Q header. */
 125                 err = vswitch_skb_checksum_setup(skb);
 126                 if (unlikely(err)) {
 127                         kfree_skb(skb);
 128                         return ERR_PTR(err);
 129                 }
 130
 131                 /* GSO is not implemented for packets with an 802.1Q header, so
 132                  * we have to do segmentation before we add that header.
 133                  *
 134                  * GSO does work with hardware-accelerated VLAN tagging, but we
 135                  * can't use hardware-accelerated VLAN tagging since it
 136                  * requires the device to have a VLAN group configured (with
 137                  * e.g. vconfig(8)) and we don't do that.
 138                  *
 139                  * Having to do this here may be a performance loss, since we
 140                  * can't take advantage of TSO hardware support, although it
 141                  * does not make a measurable network performance difference
 142                  * for 1G Ethernet.  Fixing that would require patching the
 143                  * kernel (either to add GSO support to the VLAN protocol or to
 144                  * support hardware-accelerated VLAN tagging without VLAN
 145                  * groups configured). */
 146                 if (skb_is_gso(skb)) {
 147                         struct sk_buff *segs;
 148
 149                         segs = skb_gso_segment(skb, 0);
 150                         kfree_skb(skb);
 151                         if (unlikely(IS_ERR(segs)))
 152                                 return ERR_CAST(segs);
 153
 154                         do {
 155                                 struct sk_buff *nskb = segs->next;
 156                                 int err;
 157
 158                                 segs->next = NULL;
 159
 160                                 /* GSO can change the checksum type so update.*/
 161                                 compute_ip_summed(segs, true);
 162
 163                                 segs = __vlan_put_tag(segs, tci);
 164                                 err = -ENOMEM;
 165                                 if (segs) {
 166                                         struct odp_flow_key segkey = *key;
 167                                         err = execute_actions(dp, segs,
 168                                                               &segkey, a + 1,
 169                                                               n_actions - 1,
 170                                                               gfp);
 171                                 }
 172
 173                                 if (unlikely(err)) {
 174                                         while ((segs = nskb)) {
 175                                                 nskb = segs->next;
 176                                                 segs->next = NULL;
 177                                                 kfree_skb(segs);
 178                                         }
 179                                         return ERR_PTR(err);
 180                                 }
 181
 182                                 segs = nskb;
 183                         } while (segs->next);
 184
 185                         skb = segs;
 186                         compute_ip_summed(skb, true);
 187                 }
 188
 189                 /* The hardware-accelerated version of vlan_put_tag() works
 190                  * only for a device that has a VLAN group configured (with
 191                  * e.g. vconfig(8)), so call the software-only version
 192                  * __vlan_put_tag() directly instead.
 193                  */
 194                 skb = __vlan_put_tag(skb, tci);
 195                 if (!skb)
 196                         return ERR_PTR(-ENOMEM);
 197
 198                 /* GSO doesn't fix up the hardware computed checksum so this
 199                  * will only be hit in the non-GSO case. */
 200                 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE)
 201                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 202                                                 + ETH_HLEN, VLAN_HLEN, 0));
 203         }
 204
 205         return skb;
 206 }
 207
 208 static struct sk_buff *strip_vlan(struct sk_buff *skb,
 209                                   struct odp_flow_key *key, gfp_t gfp)
 210 {
 211         skb = make_writable(skb, 0, gfp);
 212         if (skb) {
 213                 vlan_pull_tag(skb);
 214                 key->dl_vlan = htons(ODP_VLAN_NONE);
 215         }
 216         return skb;
 217 }
 218
 219 static struct sk_buff *set_dl_addr(struct sk_buff *skb,
 220                                    struct odp_flow_key *key,
 221                                    const struct odp_action_dl_addr *a,
 222                                    gfp_t gfp)
 223 {
 224         skb = make_writable(skb, 0, gfp);
 225         if (skb) {
 226                 struct ethhdr *eh = eth_hdr(skb);
 227                 if (a->type == ODPAT_SET_DL_SRC) {
 228                         memcpy(eh->h_source, a->dl_addr, ETH_ALEN);
 229                         memcpy(key->dl_src, a->dl_addr, ETH_ALEN);
 230                 } else {
 231                         memcpy(eh->h_dest, a->dl_addr, ETH_ALEN);
 232                         memcpy(key->dl_dst, a->dl_addr, ETH_ALEN);
 233                 }
 234         }
 235         return skb;
 236 }
 237
 238 /* Updates 'sum', which is a field in 'skb''s data, given that a 4-byte field
 239  * covered by the sum has been changed from 'from' to 'to'.  If set,
 240  * 'pseudohdr' indicates that the field is in the TCP or UDP pseudo-header.
 241  * Based on nf_proto_csum_replace4. */
 242 static void update_csum(__sum16 *sum, struct sk_buff *skb,
 243                         __be32 from, __be32 to, int pseudohdr)
 244 {
 245         __be32 diff[] = { ~from, to };
 246
 247         if (OVS_CB(skb)->ip_summed != OVS_CSUM_PARTIAL) {
 248                 *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
 249                                 ~csum_unfold(*sum)));
 250                 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE && pseudohdr)
 251                         skb->csum = ~csum_partial((char *)diff, sizeof(diff),
 252                                                 ~skb->csum);
 253         } else if (pseudohdr)
 254                 *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
 255                                 csum_unfold(*sum)));
 256 }
 257
 258 static struct sk_buff *set_nw_addr(struct sk_buff *skb,
 259                                    struct odp_flow_key *key,
 260                                    const struct odp_action_nw_addr *a,
 261                                    gfp_t gfp)
 262 {
 263         if (key->dl_type != htons(ETH_P_IP))
 264                 return skb;
 265
 266         skb = make_writable(skb, 0, gfp);
 267         if (skb) {
 268                 struct iphdr *nh = ip_hdr(skb);
 269                 u32 *f = a->type == ODPAT_SET_NW_SRC ? &nh->saddr : &nh->daddr;
 270                 u32 old = *f;
 271                 u32 new = a->nw_addr;
 272
 273                 if (key->nw_proto == IPPROTO_TCP) {
 274                         struct tcphdr *th = tcp_hdr(skb);
 275                         update_csum(&th->check, skb, old, new, 1);
 276                 } else if (key->nw_proto == IPPROTO_UDP) {
 277                         struct udphdr *th = udp_hdr(skb);
 278                         update_csum(&th->check, skb, old, new, 1);
 279                 }
 280                 update_csum(&nh->check, skb, old, new, 0);
 281                 *f = new;
 282
 283                 if (a->type == ODPAT_SET_NW_SRC)
 284                         key->nw_src = a->nw_addr;
 285                 else
 286                         key->nw_dst = a->nw_addr;
 287         }
 288         return skb;
 289 }
 290
 291 static struct sk_buff *set_nw_tos(struct sk_buff *skb,
 292                                    struct odp_flow_key *key,
 293                                    const struct odp_action_nw_tos *a,
 294                                    gfp_t gfp)
 295 {
 296         if (key->dl_type != htons(ETH_P_IP))
 297                 return skb;
 298
 299         skb = make_writable(skb, 0, gfp);
 300         if (skb) {
 301                 struct iphdr *nh = ip_hdr(skb);
 302                 u8 *f = &nh->tos;
 303                 u8 old = *f;
 304                 u8 new;
 305
 306                 /* Set the DSCP bits and preserve the ECN bits. */
 307                 new = a->nw_tos | (nh->tos & INET_ECN_MASK);
 308                 update_csum(&nh->check, skb, htons((uint16_t)old),
 309                                 htons((uint16_t)new), 0);
 310                 *f = new;
 311                 key->nw_tos = a->nw_tos;
 312         }
 313         return skb;
 314 }
 315
 316 static struct sk_buff *
 317 set_tp_port(struct sk_buff *skb, struct odp_flow_key *key,
 318             const struct odp_action_tp_port *a,
 319             gfp_t gfp)
 320 {
 321         int check_ofs;
 322
 323         if (key->dl_type != htons(ETH_P_IP))
 324                 return skb;
 325
 326         if (key->nw_proto == IPPROTO_TCP)
 327                 check_ofs = offsetof(struct tcphdr, check);
 328         else if (key->nw_proto == IPPROTO_UDP)
 329                 check_ofs = offsetof(struct udphdr, check);
 330         else
 331                 return skb;
 332
 333         skb = make_writable(skb, 0, gfp);
 334         if (skb) {
 335                 struct udphdr *th = udp_hdr(skb);
 336                 u16 *f = a->type == ODPAT_SET_TP_SRC ? &th->source : &th->dest;
 337                 u16 old = *f;
 338                 u16 new = a->tp_port;
 339                 update_csum((u16*)(skb_transport_header(skb) + check_ofs),
 340                                 skb, old, new, 0);
 341                 *f = new;
 342                 if (a->type == ODPAT_SET_TP_SRC)
 343                         key->tp_src = a->tp_port;
 344                 else
 345                         key->tp_dst = a->tp_port;
 346         }
 347         return skb;
 348 }
 349
 350 static inline unsigned packet_length(const struct sk_buff *skb)
 351 {
 352         unsigned length = skb->len - ETH_HLEN;
 353         if (skb->protocol == htons(ETH_P_8021Q))
 354                 length -= VLAN_HLEN;
 355         return length;
 356 }
 357
 358 static void
 359 do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 360 {
 361         struct dp_port *p;
 362         int mtu;
 363
 364         if (!skb)
 365                 goto error;
 366
 367         p = rcu_dereference(dp->ports[out_port]);
 368         if (!p)
 369                 goto error;
 370
 371         mtu = vport_get_mtu(p->vport);
 372         if (packet_length(skb) > mtu && !skb_is_gso(skb)) {
 373                 printk(KERN_WARNING "%s: dropped over-mtu packet: %d > %d\n",
 374                        dp_name(dp), packet_length(skb), mtu);
 375                 goto error;
 376         }
 377
 378         vport_send(p->vport, skb);
 379         return;
 380
 381 error:
 382         kfree_skb(skb);
 383 }
 384
 385 /* Never consumes 'skb'.  Returns a port that 'skb' should be sent to, -1 if
 386  * none.  */
 387 static int output_group(struct datapath *dp, __u16 group,
 388                         struct sk_buff *skb, gfp_t gfp)
 389 {
 390         struct dp_port_group *g = rcu_dereference(dp->groups[group]);
 391         int prev_port = -1;
 392         int i;
 393
 394         if (!g)
 395                 return -1;
 396         for (i = 0; i < g->n_ports; i++) {
 397                 struct dp_port *p = rcu_dereference(dp->ports[g->ports[i]]);
 398                 if (!p || OVS_CB(skb)->dp_port == p)
 399                         continue;
 400                 if (prev_port != -1) {
 401                         struct sk_buff *clone = skb_clone(skb, gfp);
 402                         if (!clone)
 403                                 return -1;
 404                         do_output(dp, clone, prev_port);
 405                 }
 406                 prev_port = p->port_no;
 407         }
 408         return prev_port;
 409 }
 410
 411 static int
 412 output_control(struct datapath *dp, struct sk_buff *skb, u32 arg, gfp_t gfp)
 413 {
 414         skb = skb_clone(skb, gfp);
 415         if (!skb)
 416                 return -ENOMEM;
 417         return dp_output_control(dp, skb, _ODPL_ACTION_NR, arg);
 418 }
 419
 420 /* Send a copy of this packet up to the sFlow agent, along with extra
 421  * information about what happened to it. */
 422 static void sflow_sample(struct datapath *dp, struct sk_buff *skb,
 423                          const union odp_action *a, int n_actions,
 424                          gfp_t gfp, struct dp_port *dp_port)
 425 {
 426         struct odp_sflow_sample_header *hdr;
 427         unsigned int actlen = n_actions * sizeof(union odp_action);
 428         unsigned int hdrlen = sizeof(struct odp_sflow_sample_header);
 429         struct sk_buff *nskb;
 430
 431         nskb = skb_copy_expand(skb, actlen + hdrlen, 0, gfp);
 432         if (!nskb)
 433                 return;
 434
 435         memcpy(__skb_push(nskb, actlen), a, actlen);
 436         hdr = (struct odp_sflow_sample_header*)__skb_push(nskb, hdrlen);
 437         hdr->n_actions = n_actions;
 438         hdr->sample_pool = atomic_read(&dp_port->sflow_pool);
 439         dp_output_control(dp, nskb, _ODPL_SFLOW_NR, 0);
 440 }
 441
 442 /* Execute a list of actions against 'skb'. */
 443 int execute_actions(struct datapath *dp, struct sk_buff *skb,
 444                     struct odp_flow_key *key,
 445                     const union odp_action *a, int n_actions,
 446                     gfp_t gfp)
 447 {
 448         /* Every output action needs a separate clone of 'skb', but the common
 449          * case is just a single output action, so that doing a clone and
 450          * then freeing the original skbuff is wasteful.  So the following code
 451          * is slightly obscure just to avoid that. */
 452         int prev_port = -1;
 453         u32 priority = skb->priority;
 454         int err;
 455
 456         if (dp->sflow_probability) {
 457                 struct dp_port *p = OVS_CB(skb)->dp_port;
 458                 if (p) {
 459                         atomic_inc(&p->sflow_pool);
 460                         if (dp->sflow_probability == UINT_MAX ||
 461                             net_random() < dp->sflow_probability)
 462                                 sflow_sample(dp, skb, a, n_actions, gfp, p);
 463                 }
 464         }
 465
 466         OVS_CB(skb)->tun_id = 0;
 467
 468         for (; n_actions > 0; a++, n_actions--) {
 469                 WARN_ON_ONCE(skb_shared(skb));
 470                 if (prev_port != -1) {
 471                         do_output(dp, skb_clone(skb, gfp), prev_port);
 472                         prev_port = -1;
 473                 }
 474
 475                 switch (a->type) {
 476                 case ODPAT_OUTPUT:
 477                         prev_port = a->output.port;
 478                         break;
 479
 480                 case ODPAT_OUTPUT_GROUP:
 481                         prev_port = output_group(dp, a->output_group.group,
 482                                                  skb, gfp);
 483                         break;
 484
 485                 case ODPAT_CONTROLLER:
 486                         err = output_control(dp, skb, a->controller.arg, gfp);
 487                         if (err) {
 488                                 kfree_skb(skb);
 489                                 return err;
 490                         }
 491                         break;
 492
 493                 case ODPAT_SET_TUNNEL:
 494                         set_tunnel(skb, key, a->tunnel.tun_id);
 495                         break;
 496
 497                 case ODPAT_SET_VLAN_VID:
 498                 case ODPAT_SET_VLAN_PCP:
 499                         skb = modify_vlan_tci(dp, skb, key, a, n_actions, gfp);
 500                         if (IS_ERR(skb))
 501                                 return PTR_ERR(skb);
 502                         break;
 503
 504                 case ODPAT_STRIP_VLAN:
 505                         skb = strip_vlan(skb, key, gfp);
 506                         break;
 507
 508                 case ODPAT_SET_DL_SRC:
 509                 case ODPAT_SET_DL_DST:
 510                         skb = set_dl_addr(skb, key, &a->dl_addr, gfp);
 511                         break;
 512
 513                 case ODPAT_SET_NW_SRC:
 514                 case ODPAT_SET_NW_DST:
 515                         skb = set_nw_addr(skb, key, &a->nw_addr, gfp);
 516                         break;
 517
 518                 case ODPAT_SET_NW_TOS:
 519                         skb = set_nw_tos(skb, key, &a->nw_tos, gfp);
 520                         break;
 521
 522                 case ODPAT_SET_TP_SRC:
 523                 case ODPAT_SET_TP_DST:
 524                         skb = set_tp_port(skb, key, &a->tp_port, gfp);
 525                         break;
 526
 527                 case ODPAT_SET_PRIORITY:
 528                         skb->priority = a->priority.priority;
 529                         break;
 530
 531                 case ODPAT_POP_PRIORITY:
 532                         skb->priority = priority;
 533                         break;
 534                 }
 535                 if (!skb)
 536                         return -ENOMEM;
 537         }
 538         if (prev_port != -1)
 539                 do_output(dp, skb, prev_port);
 540         else
 541                 kfree_skb(skb);
 542         return 0;
 543 }