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