datapath/actions.c

   1 /*
   2  * Distributed under the terms of the GNU GPL version 2.
   3  * Copyright (c) 2007, 2008, 2009 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/ip.h>
  19 #include <net/checksum.h>
  20 #include "datapath.h"
  21 #include "dp_dev.h"
  22 #include "actions.h"
  23 #include "openvswitch/datapath-protocol.h"
  24
  25 static struct sk_buff *
  26 make_writable(struct sk_buff *skb, unsigned min_headroom, gfp_t gfp)
  27 {
  28         if (skb_shared(skb) || skb_cloned(skb)) {
  29                 struct sk_buff *nskb;
  30                 unsigned headroom = max(min_headroom, skb_headroom(skb));
  31
  32                 nskb = skb_copy_expand(skb, headroom, skb_tailroom(skb), gfp);
  33                 if (nskb) {
  34 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
  35                         /* Before 2.6.24 these fields were not copied when
  36                          * doing an skb_copy_expand. */
  37                         nskb->ip_summed = skb->ip_summed;
  38                         nskb->csum = skb->csum;
  39 #endif
  40 #if defined(CONFIG_XEN) && LINUX_VERSION_CODE == KERNEL_VERSION(2,6,18)
  41                         /* These fields are copied in skb_clone but not in
  42                          * skb_copy or related functions.  We need to manually
  43                          * copy them over here. */
  44                         nskb->proto_data_valid = skb->proto_data_valid;
  45                         nskb->proto_csum_blank = skb->proto_csum_blank;
  46 #endif
  47                         kfree_skb(skb);
  48                         return nskb;
  49                 }
  50         } else {
  51                 unsigned int hdr_len = (skb_transport_offset(skb)
  52                                         + sizeof(struct tcphdr));
  53                 if (pskb_may_pull(skb, min(hdr_len, skb->len)))
  54                         return skb;
  55         }
  56         kfree_skb(skb);
  57         return NULL;
  58 }
  59
  60
  61 static struct sk_buff *
  62 vlan_pull_tag(struct sk_buff *skb)
  63 {
  64         struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
  65         struct ethhdr *eh;
  66
  67
  68         /* Verify we were given a vlan packet */
  69         if (vh->h_vlan_proto != htons(ETH_P_8021Q))
  70                 return skb;
  71
  72         memmove(skb->data + VLAN_HLEN, skb->data, 2 * VLAN_ETH_ALEN);
  73
  74         eh = (struct ethhdr *)skb_pull(skb, VLAN_HLEN);
  75
  76         skb->protocol = eh->h_proto;
  77         skb->mac_header += VLAN_HLEN;
  78
  79         return skb;
  80 }
  81
  82
  83 static struct sk_buff *
  84 modify_vlan_tci(struct datapath *dp, struct sk_buff *skb,
  85                 struct odp_flow_key *key, const union odp_action *a,
  86                 int n_actions, gfp_t gfp)
  87 {
  88         u16 tci, mask;
  89
  90         if (a->type == ODPAT_SET_VLAN_VID) {
  91                 tci = ntohs(a->vlan_vid.vlan_vid);
  92                 mask = VLAN_VID_MASK;
  93                 key->dl_vlan = htons(tci & mask);
  94         } else {
  95                 tci = a->vlan_pcp.vlan_pcp << 13;
  96                 mask = VLAN_PCP_MASK;
  97         }
  98
  99         skb = make_writable(skb, VLAN_HLEN, gfp);
 100         if (!skb)
 101                 return ERR_PTR(-ENOMEM);
 102
 103         if (skb->protocol == htons(ETH_P_8021Q)) {
 104                 /* Modify vlan id, but maintain other TCI values */
 105                 struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
 106                 vh->h_vlan_TCI = htons((ntohs(vh->h_vlan_TCI) & ~mask) | tci);
 107         } else {
 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                 vswitch_skb_checksum_setup(skb);
 116
 117                 /* GSO is not implemented for packets with an 802.1Q header, so
 118                  * we have to do segmentation before we add that header.
 119                  *
 120                  * GSO does work with hardware-accelerated VLAN tagging, but we
 121                  * can't use hardware-accelerated VLAN tagging since it
 122                  * requires the device to have a VLAN group configured (with
 123                  * e.g. vconfig(8)) and we don't do that.
 124                  *
 125                  * Having to do this here may be a performance loss, since we
 126                  * can't take advantage of TSO hardware support, although it
 127                  * does not make a measurable network performance difference
 128                  * for 1G Ethernet.  Fixing that would require patching the
 129                  * kernel (either to add GSO support to the VLAN protocol or to
 130                  * support hardware-accelerated VLAN tagging without VLAN
 131                  * groups configured). */
 132                 if (skb_is_gso(skb)) {
 133                         struct sk_buff *segs;
 134
 135                         segs = skb_gso_segment(skb, 0);
 136                         kfree_skb(skb);
 137                         if (unlikely(IS_ERR(segs)))
 138                                 return ERR_CAST(segs);
 139
 140                         do {
 141                                 struct sk_buff *nskb = segs->next;
 142                                 int err;
 143
 144                                 segs->next = NULL;
 145
 146                                 segs = __vlan_put_tag(segs, tci);
 147                                 err = -ENOMEM;
 148                                 if (segs) {
 149                                         struct odp_flow_key segkey = *key;
 150                                         err = execute_actions(dp, segs,
 151                                                               &segkey, a + 1,
 152                                                               n_actions - 1,
 153                                                               gfp);
 154                                 }
 155
 156                                 if (unlikely(err)) {
 157                                         while ((segs = nskb)) {
 158                                                 nskb = segs->next;
 159                                                 segs->next = NULL;
 160                                                 kfree_skb(segs);
 161                                         }
 162                                         return ERR_PTR(err);
 163                                 }
 164
 165                                 segs = nskb;
 166                         } while (segs->next);
 167
 168                         skb = segs;
 169                 }
 170
 171                 /* The hardware-accelerated version of vlan_put_tag() works
 172                  * only for a device that has a VLAN group configured (with
 173                  * e.g. vconfig(8)), so call the software-only version
 174                  * __vlan_put_tag() directly instead.
 175                  */
 176                 skb = __vlan_put_tag(skb, tci);
 177                 if (!skb)
 178                         return ERR_PTR(-ENOMEM);
 179         }
 180
 181         return skb;
 182 }
 183
 184 static struct sk_buff *strip_vlan(struct sk_buff *skb,
 185                                   struct odp_flow_key *key, gfp_t gfp)
 186 {
 187         skb = make_writable(skb, 0, gfp);
 188         if (skb) {
 189                 vlan_pull_tag(skb);
 190                 key->dl_vlan = htons(ODP_VLAN_NONE);
 191         }
 192         return skb;
 193 }
 194
 195 static struct sk_buff *set_dl_addr(struct sk_buff *skb,
 196                                    const struct odp_action_dl_addr *a,
 197                                    gfp_t gfp)
 198 {
 199         skb = make_writable(skb, 0, gfp);
 200         if (skb) {
 201                 struct ethhdr *eh = eth_hdr(skb);
 202                 memcpy(a->type == ODPAT_SET_DL_SRC ? eh->h_source : eh->h_dest,
 203                        a->dl_addr, ETH_ALEN);
 204         }
 205         return skb;
 206 }
 207
 208 /* Updates 'sum', which is a field in 'skb''s data, given that a 4-byte field
 209  * covered by the sum has been changed from 'from' to 'to'.  If set,
 210  * 'pseudohdr' indicates that the field is in the TCP or UDP pseudo-header.
 211  * Based on nf_proto_csum_replace4. */
 212 static void update_csum(__sum16 *sum, struct sk_buff *skb,
 213                         __be32 from, __be32 to, int pseudohdr)
 214 {
 215         __be32 diff[] = { ~from, to };
 216         if (skb->ip_summed != CHECKSUM_PARTIAL) {
 217                 *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
 218                                 ~csum_unfold(*sum)));
 219                 if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
 220                         skb->csum = ~csum_partial((char *)diff, sizeof(diff),
 221                                                 ~skb->csum);
 222         } else if (pseudohdr)
 223                 *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
 224                                 csum_unfold(*sum)));
 225 }
 226
 227 static struct sk_buff *set_nw_addr(struct sk_buff *skb,
 228                                    struct odp_flow_key *key,
 229                                    const struct odp_action_nw_addr *a,
 230                                    gfp_t gfp)
 231 {
 232         if (key->dl_type != htons(ETH_P_IP))
 233                 return skb;
 234
 235         skb = make_writable(skb, 0, gfp);
 236         if (skb) {
 237                 struct iphdr *nh = ip_hdr(skb);
 238                 u32 *f = a->type == ODPAT_SET_NW_SRC ? &nh->saddr : &nh->daddr;
 239                 u32 old = *f;
 240                 u32 new = a->nw_addr;
 241
 242                 if (key->nw_proto == IPPROTO_TCP) {
 243                         struct tcphdr *th = tcp_hdr(skb);
 244                         update_csum(&th->check, skb, old, new, 1);
 245                 } else if (key->nw_proto == IPPROTO_UDP) {
 246                         struct udphdr *th = udp_hdr(skb);
 247                         update_csum(&th->check, skb, old, new, 1);
 248                 }
 249                 update_csum(&nh->check, skb, old, new, 0);
 250                 *f = new;
 251         }
 252         return skb;
 253 }
 254
 255 static struct sk_buff *
 256 set_tp_port(struct sk_buff *skb, struct odp_flow_key *key,
 257             const struct odp_action_tp_port *a,
 258             gfp_t gfp)
 259 {
 260         int check_ofs;
 261
 262         if (key->dl_type != htons(ETH_P_IP))
 263                 return skb;
 264
 265         if (key->nw_proto == IPPROTO_TCP)
 266                 check_ofs = offsetof(struct tcphdr, check);
 267         else if (key->nw_proto == IPPROTO_UDP)
 268                 check_ofs = offsetof(struct udphdr, check);
 269         else
 270                 return skb;
 271
 272         skb = make_writable(skb, 0, gfp);
 273         if (skb) {
 274                 struct udphdr *th = udp_hdr(skb);
 275                 u16 *f = a->type == ODPAT_SET_TP_SRC ? &th->source : &th->dest;
 276                 u16 old = *f;
 277                 u16 new = a->tp_port;
 278                 update_csum((u16*)(skb_transport_header(skb) + check_ofs),
 279                                 skb, old, new, 1);
 280                 *f = new;
 281         }
 282         return skb;
 283 }
 284
 285 static inline unsigned packet_length(const struct sk_buff *skb)
 286 {
 287         unsigned length = skb->len - ETH_HLEN;
 288         if (skb->protocol == htons(ETH_P_8021Q))
 289                 length -= VLAN_HLEN;
 290         return length;
 291 }
 292
 293 int dp_xmit_skb(struct sk_buff *skb)
 294 {
 295         struct datapath *dp = skb->dev->br_port->dp;
 296         int len = skb->len;
 297
 298         if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) {
 299                 printk(KERN_WARNING "%s: dropped over-mtu packet: %d > %d\n",
 300                        dp_name(dp), packet_length(skb), skb->dev->mtu);
 301                 kfree_skb(skb);
 302                 return -E2BIG;
 303         }
 304
 305         dev_queue_xmit(skb);
 306
 307         return len;
 308 }
 309
 310 static void
 311 do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 312 {
 313         struct net_bridge_port *p;
 314         struct net_device *dev;
 315
 316         if (!skb)
 317                 goto error;
 318
 319         p = dp->ports[out_port];
 320         if (!p)
 321                 goto error;
 322
 323         dev = skb->dev = p->dev;
 324         if (is_dp_dev(dev))
 325                 dp_dev_recv(dev, skb);
 326         else
 327                 dp_xmit_skb(skb);
 328         return;
 329
 330 error:
 331         kfree_skb(skb);
 332 }
 333
 334 /* Never consumes 'skb'.  Returns a port that 'skb' should be sent to, -1 if
 335  * none.  */
 336 static int output_group(struct datapath *dp, __u16 group,
 337                         struct sk_buff *skb, gfp_t gfp)
 338 {
 339         struct dp_port_group *g = rcu_dereference(dp->groups[group]);
 340         int prev_port = -1;
 341         int i;
 342
 343         if (!g)
 344                 return -1;
 345         for (i = 0; i < g->n_ports; i++) {
 346                 struct net_bridge_port *p = dp->ports[g->ports[i]];
 347                 if (!p || skb->dev == p->dev)
 348                         continue;
 349                 if (prev_port != -1) {
 350                         struct sk_buff *clone = skb_clone(skb, gfp);
 351                         if (!clone)
 352                                 return -1;
 353                         do_output(dp, clone, prev_port);
 354                 }
 355                 prev_port = p->port_no;
 356         }
 357         return prev_port;
 358 }
 359
 360 static int
 361 output_control(struct datapath *dp, struct sk_buff *skb, u32 arg, gfp_t gfp)
 362 {
 363         skb = skb_clone(skb, gfp);
 364         if (!skb)
 365                 return -ENOMEM;
 366         return dp_output_control(dp, skb, _ODPL_ACTION_NR, arg);
 367 }
 368
 369 /* Execute a list of actions against 'skb'. */
 370 int execute_actions(struct datapath *dp, struct sk_buff *skb,
 371                     struct odp_flow_key *key,
 372                     const union odp_action *a, int n_actions,
 373                     gfp_t gfp)
 374 {
 375         /* Every output action needs a separate clone of 'skb', but the common
 376          * case is just a single output action, so that doing a clone and
 377          * then freeing the original skbuff is wasteful.  So the following code
 378          * is slightly obscure just to avoid that. */
 379         int prev_port = -1;
 380         int err;
 381         for (; n_actions > 0; a++, n_actions--) {
 382                 WARN_ON_ONCE(skb_shared(skb));
 383                 if (prev_port != -1) {
 384                         do_output(dp, skb_clone(skb, gfp), prev_port);
 385                         prev_port = -1;
 386                 }
 387
 388                 switch (a->type) {
 389                 case ODPAT_OUTPUT:
 390                         prev_port = a->output.port;
 391                         break;
 392
 393                 case ODPAT_OUTPUT_GROUP:
 394                         prev_port = output_group(dp, a->output_group.group,
 395                                                  skb, gfp);
 396                         break;
 397
 398                 case ODPAT_CONTROLLER:
 399                         err = output_control(dp, skb, a->controller.arg, gfp);
 400                         if (err) {
 401                                 kfree_skb(skb);
 402                                 return err;
 403                         }
 404                         break;
 405
 406                 case ODPAT_SET_VLAN_VID:
 407                 case ODPAT_SET_VLAN_PCP:
 408                         skb = modify_vlan_tci(dp, skb, key, a, n_actions, gfp);
 409                         if (IS_ERR(skb))
 410                                 return PTR_ERR(skb);
 411                         break;
 412
 413                 case ODPAT_STRIP_VLAN:
 414                         skb = strip_vlan(skb, key, gfp);
 415                         break;
 416
 417                 case ODPAT_SET_DL_SRC:
 418                 case ODPAT_SET_DL_DST:
 419                         skb = set_dl_addr(skb, &a->dl_addr, gfp);
 420                         break;
 421
 422                 case ODPAT_SET_NW_SRC:
 423                 case ODPAT_SET_NW_DST:
 424                         skb = set_nw_addr(skb, key, &a->nw_addr, gfp);
 425                         break;
 426
 427                 case ODPAT_SET_TP_SRC:
 428                 case ODPAT_SET_TP_DST:
 429                         skb = set_tp_port(skb, key, &a->tp_port, gfp);
 430                         break;
 431                 }
 432                 if (!skb)
 433                         return -ENOMEM;
 434         }
 435         if (prev_port != -1)
 436                 do_output(dp, skb, prev_port);
 437         else
 438                 kfree_skb(skb);
 439         return 0;
 440 }