datapath/actions.c

   1 /*
   2  * Distributed under the terms of the GNU GPL version 2.
   3  * Copyright (c) 2007, 2008, 2009, 2010, 2011 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/skbuff.h>
  14 #include <linux/in.h>
  15 #include <linux/ip.h>
  16 #include <linux/openvswitch.h>
  17 #include <linux/tcp.h>
  18 #include <linux/udp.h>
  19 #include <linux/in6.h>
  20 #include <linux/if_arp.h>
  21 #include <linux/if_vlan.h>
  22 #include <net/ip.h>
  23 #include <net/checksum.h>
  24 #include <net/dsfield.h>
  25
  26 #include "checksum.h"
  27 #include "datapath.h"
  28 #include "vlan.h"
  29 #include "vport.h"
  30
  31 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  32                         const struct nlattr *attr, int len, bool keep_skb);
  33
  34 static int make_writable(struct sk_buff *skb, int write_len)
  35 {
  36         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
  37                 return 0;
  38
  39         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  40 }
  41
  42 /* remove VLAN header from packet and update csum accrodingly. */
  43 static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
  44 {
  45         struct ethhdr *eh;
  46         struct vlan_ethhdr *veth;
  47         int err;
  48
  49         err = make_writable(skb, VLAN_ETH_HLEN);
  50         if (unlikely(err))
  51                 return err;
  52
  53         if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
  54                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  55                                         + ETH_HLEN, VLAN_HLEN, 0));
  56
  57         veth = (struct vlan_ethhdr *) skb->data;
  58         *current_tci = veth->h_vlan_TCI;
  59
  60         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
  61
  62         eh = (struct ethhdr *)__skb_pull(skb, VLAN_HLEN);
  63
  64         skb->protocol = eh->h_proto;
  65         skb->mac_header += VLAN_HLEN;
  66
  67         return 0;
  68 }
  69
  70 static int pop_vlan(struct sk_buff *skb)
  71 {
  72         __be16 tci;
  73         int err;
  74
  75         if (likely(vlan_tx_tag_present(skb))) {
  76                 vlan_set_tci(skb, 0);
  77         } else {
  78                 if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
  79                              skb->len < VLAN_ETH_HLEN))
  80                         return 0;
  81
  82                 err = __pop_vlan_tci(skb, &tci);
  83                 if (err)
  84                         return err;
  85         }
  86         /* move next vlan tag to hw accel tag */
  87         if (likely(skb->protocol != htons(ETH_P_8021Q) ||
  88                    skb->len < VLAN_ETH_HLEN))
  89                 return 0;
  90
  91         err = __pop_vlan_tci(skb, &tci);
  92         if (unlikely(err))
  93                 return err;
  94
  95         __vlan_hwaccel_put_tag(skb, ntohs(tci));
  96         return 0;
  97 }
  98
  99 static int push_vlan(struct sk_buff *skb, const struct ovs_key_8021q *q_key)
 100 {
 101         if (unlikely(vlan_tx_tag_present(skb))) {
 102                 u16 current_tag;
 103
 104                 /* push down current VLAN tag */
 105                 current_tag = vlan_tx_tag_get(skb);
 106
 107                 if (!__vlan_put_tag(skb, current_tag))
 108                         return -ENOMEM;
 109
 110                 if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
 111                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 112                                         + ETH_HLEN, VLAN_HLEN, 0));
 113
 114         }
 115         __vlan_hwaccel_put_tag(skb, ntohs(q_key->q_tci));
 116         return 0;
 117 }
 118
 119 static int set_eth_addr(struct sk_buff *skb,
 120                         const struct ovs_key_ethernet *eth_key)
 121 {
 122         int err;
 123         err = make_writable(skb, ETH_HLEN);
 124         if (unlikely(err))
 125                 return err;
 126
 127         memcpy(eth_hdr(skb)->h_source, eth_key->eth_src, ETH_HLEN);
 128         memcpy(eth_hdr(skb)->h_dest, eth_key->eth_dst, ETH_HLEN);
 129
 130         return 0;
 131 }
 132
 133 static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
 134                                 __be32 *addr, __be32 new_addr)
 135 {
 136         int transport_len = skb->len - skb_transport_offset(skb);
 137
 138         if (nh->protocol == IPPROTO_TCP) {
 139                 if (likely(transport_len >= sizeof(struct tcphdr)))
 140                         inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
 141                                                  *addr, new_addr, 1);
 142         } else if (nh->protocol == IPPROTO_UDP) {
 143                 if (likely(transport_len >= sizeof(struct udphdr)))
 144                         inet_proto_csum_replace4(&udp_hdr(skb)->check, skb,
 145                                                  *addr, new_addr, 1);
 146         }
 147
 148         csum_replace4(&nh->check, *addr, new_addr);
 149         skb_clear_rxhash(skb);
 150         *addr = new_addr;
 151 }
 152
 153 static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
 154 {
 155         csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
 156         nh->ttl = new_ttl;
 157 }
 158
 159 static int set_ipv4(struct sk_buff *skb, const struct ovs_key_ipv4 *ipv4_key)
 160 {
 161         struct iphdr *nh;
 162         int err;
 163
 164         err = make_writable(skb, skb_network_offset(skb) +
 165                                  sizeof(struct iphdr));
 166         if (unlikely(err))
 167                 return err;
 168
 169         nh = ip_hdr(skb);
 170
 171         if (ipv4_key->ipv4_src != nh->saddr)
 172                 set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
 173
 174         if (ipv4_key->ipv4_dst != nh->daddr)
 175                 set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
 176
 177         if (ipv4_key->ipv4_tos != nh->tos)
 178                 ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
 179
 180         if (ipv4_key->ipv4_ttl != nh->ttl)
 181                 set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
 182
 183         return 0;
 184 }
 185
 186 /* Must follow make_writable() since that can move the skb data. */
 187 static void set_tp_port(struct sk_buff *skb, __be16 *port,
 188                          __be16 new_port, __sum16 *check)
 189 {
 190         inet_proto_csum_replace2(check, skb, *port, new_port, 0);
 191         *port = new_port;
 192         skb_clear_rxhash(skb);
 193 }
 194
 195 static int set_udp_port(struct sk_buff *skb,
 196                         const struct ovs_key_udp *udp_port_key)
 197 {
 198         struct udphdr *uh;
 199         int err;
 200
 201         err = make_writable(skb, skb_transport_offset(skb) +
 202                                  sizeof(struct udphdr));
 203         if (unlikely(err))
 204                 return err;
 205
 206         uh = udp_hdr(skb);
 207         if (udp_port_key->udp_src != uh->source)
 208                 set_tp_port(skb, &uh->source, udp_port_key->udp_src, &uh->check);
 209
 210         if (udp_port_key->udp_dst != uh->dest)
 211                 set_tp_port(skb, &uh->dest, udp_port_key->udp_dst, &uh->check);
 212
 213         return 0;
 214 }
 215
 216 static int set_tcp_port(struct sk_buff *skb,
 217                         const struct ovs_key_tcp *tcp_port_key)
 218 {
 219         struct tcphdr *th;
 220         int err;
 221
 222         err = make_writable(skb, skb_transport_offset(skb) +
 223                                  sizeof(struct tcphdr));
 224         if (unlikely(err))
 225                 return err;
 226
 227         th = tcp_hdr(skb);
 228         if (tcp_port_key->tcp_src != th->source)
 229                 set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
 230
 231         if (tcp_port_key->tcp_dst != th->dest)
 232                 set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
 233
 234         return 0;
 235 }
 236
 237 static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 238 {
 239         struct vport *vport;
 240
 241         if (unlikely(!skb))
 242                 return -ENOMEM;
 243
 244         vport = rcu_dereference(dp->ports[out_port]);
 245         if (unlikely(!vport)) {
 246                 kfree_skb(skb);
 247                 return -ENODEV;
 248         }
 249
 250         vport_send(vport, skb);
 251         return 0;
 252 }
 253
 254 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 255                             const struct nlattr *attr)
 256 {
 257         struct dp_upcall_info upcall;
 258         const struct nlattr *a;
 259         int rem;
 260
 261         upcall.cmd = OVS_PACKET_CMD_ACTION;
 262         upcall.key = &OVS_CB(skb)->flow->key;
 263         upcall.userdata = NULL;
 264         upcall.pid = 0;
 265
 266         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 267                  a = nla_next(a, &rem)) {
 268                 switch (nla_type(a)) {
 269                 case OVS_USERSPACE_ATTR_USERDATA:
 270                         upcall.userdata = a;
 271                         break;
 272
 273                 case OVS_USERSPACE_ATTR_PID:
 274                         upcall.pid = nla_get_u32(a);
 275                         break;
 276                 }
 277         }
 278
 279         return dp_upcall(dp, skb, &upcall);
 280 }
 281
 282 static int sample(struct datapath *dp, struct sk_buff *skb,
 283                   const struct nlattr *attr)
 284 {
 285         const struct nlattr *acts_list = NULL;
 286         const struct nlattr *a;
 287         int rem;
 288
 289         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 290                  a = nla_next(a, &rem)) {
 291                 switch (nla_type(a)) {
 292                 case OVS_SAMPLE_ATTR_PROBABILITY:
 293                         if (net_random() >= nla_get_u32(a))
 294                                 return 0;
 295                         break;
 296
 297                 case OVS_SAMPLE_ATTR_ACTIONS:
 298                         acts_list = a;
 299                         break;
 300                 }
 301         }
 302
 303         return do_execute_actions(dp, skb, nla_data(acts_list),
 304                                                  nla_len(acts_list), true);
 305 }
 306
 307 static int execute_set_action(struct sk_buff *skb,
 308                                  const struct nlattr *nested_attr)
 309 {
 310         int err = 0;
 311
 312         switch (nla_type(nested_attr)) {
 313         case OVS_KEY_ATTR_PRIORITY:
 314                 skb->priority = nla_get_u32(nested_attr);
 315                 break;
 316
 317         case OVS_KEY_ATTR_TUN_ID:
 318                 OVS_CB(skb)->tun_id = nla_get_be64(nested_attr);
 319                 break;
 320
 321         case OVS_KEY_ATTR_ETHERNET:
 322                 err = set_eth_addr(skb, nla_data(nested_attr));
 323                 break;
 324
 325         case OVS_KEY_ATTR_IPV4:
 326                 err = set_ipv4(skb, nla_data(nested_attr));
 327                 break;
 328
 329         case OVS_KEY_ATTR_TCP:
 330                 err = set_tcp_port(skb, nla_data(nested_attr));
 331                 break;
 332
 333         case OVS_KEY_ATTR_UDP:
 334                 err = set_udp_port(skb, nla_data(nested_attr));
 335                 break;
 336         }
 337
 338         return err;
 339 }
 340
 341 /* Execute a list of actions against 'skb'. */
 342 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 343                         const struct nlattr *attr, int len, bool keep_skb)
 344 {
 345         /* Every output action needs a separate clone of 'skb', but the common
 346          * case is just a single output action, so that doing a clone and
 347          * then freeing the original skbuff is wasteful.  So the following code
 348          * is slightly obscure just to avoid that. */
 349         int prev_port = -1;
 350         const struct nlattr *a;
 351         int rem;
 352
 353         for (a = attr, rem = len; rem > 0;
 354              a = nla_next(a, &rem)) {
 355                 int err = 0;
 356
 357                 if (prev_port != -1) {
 358                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 359                         prev_port = -1;
 360                 }
 361
 362                 switch (nla_type(a)) {
 363                 case OVS_ACTION_ATTR_OUTPUT:
 364                         prev_port = nla_get_u32(a);
 365                         break;
 366
 367                 case OVS_ACTION_ATTR_USERSPACE:
 368                         output_userspace(dp, skb, a);
 369                         break;
 370
 371                 case OVS_ACTION_ATTR_PUSH:
 372                         /* Only supported push action is on vlan tag. */
 373                         err = push_vlan(skb, nla_data(nla_data(a)));
 374                         if (unlikely(err)) /* skb already freed. */
 375                                 return err;
 376                         break;
 377
 378                 case OVS_ACTION_ATTR_POP:
 379                         /* Only supported pop action is on vlan tag. */
 380                         err = pop_vlan(skb);
 381                         break;
 382
 383                 case OVS_ACTION_ATTR_SET:
 384                         err = execute_set_action(skb, nla_data(a));
 385                         break;
 386
 387                 case OVS_ACTION_ATTR_SAMPLE:
 388                         err = sample(dp, skb, a);
 389                         break;
 390                 }
 391
 392                 if (unlikely(err)) {
 393                         kfree_skb(skb);
 394                         return err;
 395                 }
 396         }
 397
 398         if (prev_port != -1) {
 399                 if (keep_skb)
 400                         skb = skb_clone(skb, GFP_ATOMIC);
 401
 402                 do_output(dp, skb, prev_port);
 403         } else if (!keep_skb)
 404                 consume_skb(skb);
 405
 406         return 0;
 407 }
 408
 409 /* We limit the number of times that we pass into execute_actions()
 410  * to avoid blowing out the stack in the event that we have a loop. */
 411 #define MAX_LOOPS 5
 412
 413 struct loop_counter {
 414         u8 count;               /* Count. */
 415         bool looping;           /* Loop detected? */
 416 };
 417
 418 static DEFINE_PER_CPU(struct loop_counter, loop_counters);
 419
 420 static int loop_suppress(struct datapath *dp, struct sw_flow_actions *actions)
 421 {
 422         if (net_ratelimit())
 423                 pr_warn("%s: flow looped %d times, dropping\n",
 424                                 dp_name(dp), MAX_LOOPS);
 425         actions->actions_len = 0;
 426         return -ELOOP;
 427 }
 428
 429 /* Execute a list of actions against 'skb'. */
 430 int execute_actions(struct datapath *dp, struct sk_buff *skb)
 431 {
 432         struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 433         struct loop_counter *loop;
 434         int error;
 435
 436         /* Check whether we've looped too much. */
 437         loop = &__get_cpu_var(loop_counters);
 438         if (unlikely(++loop->count > MAX_LOOPS))
 439                 loop->looping = true;
 440         if (unlikely(loop->looping)) {
 441                 error = loop_suppress(dp, acts);
 442                 kfree_skb(skb);
 443                 goto out_loop;
 444         }
 445
 446         OVS_CB(skb)->tun_id = 0;
 447         error = do_execute_actions(dp, skb, acts->actions,
 448                                          acts->actions_len, false);
 449
 450         /* Check whether sub-actions looped too much. */
 451         if (unlikely(loop->looping))
 452                 error = loop_suppress(dp, acts);
 453
 454 out_loop:
 455         /* Decrement loop counter. */
 456         if (!--loop->count)
 457                 loop->looping = false;
 458
 459         return error;
 460 }