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 #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_arp.h>
  18 #include <linux/if_vlan.h>
  19 #include <net/inet_ecn.h>
  20 #include <net/ip.h>
  21 #include <net/checksum.h>
  22
  23 #include "actions.h"
  24 #include "checksum.h"
  25 #include "datapath.h"
  26 #include "openvswitch/datapath-protocol.h"
  27 #include "vlan.h"
  28 #include "vport.h"
  29
  30 static int do_execute_actions(struct datapath *, struct sk_buff *,
  31                               const struct sw_flow_key *,
  32                               const struct nlattr *actions, u32 actions_len);
  33
  34 static struct sk_buff *make_writable(struct sk_buff *skb, unsigned min_headroom)
  35 {
  36         if (skb_cloned(skb)) {
  37                 struct sk_buff *nskb;
  38                 unsigned headroom = max(min_headroom, skb_headroom(skb));
  39
  40                 nskb = skb_copy_expand(skb, headroom, skb_tailroom(skb), GFP_ATOMIC);
  41                 if (nskb) {
  42                         set_skb_csum_bits(skb, nskb);
  43                         kfree_skb(skb);
  44                         return nskb;
  45                 }
  46         } else {
  47                 unsigned int hdr_len = (skb_transport_offset(skb)
  48                                         + sizeof(struct tcphdr));
  49                 if (pskb_may_pull(skb, min(hdr_len, skb->len)))
  50                         return skb;
  51         }
  52         kfree_skb(skb);
  53         return NULL;
  54 }
  55
  56 static struct sk_buff *strip_vlan(struct sk_buff *skb)
  57 {
  58         struct ethhdr *eh;
  59
  60         if (vlan_tx_tag_present(skb)) {
  61                 vlan_set_tci(skb, 0);
  62                 return skb;
  63         }
  64
  65         if (unlikely(vlan_eth_hdr(skb)->h_vlan_proto != htons(ETH_P_8021Q) ||
  66             skb->len < VLAN_ETH_HLEN))
  67                 return skb;
  68
  69         skb = make_writable(skb, 0);
  70         if (unlikely(!skb))
  71                 return NULL;
  72
  73         if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
  74                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  75                                         + ETH_HLEN, VLAN_HLEN, 0));
  76
  77         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
  78
  79         eh = (struct ethhdr *)skb_pull(skb, VLAN_HLEN);
  80
  81         skb->protocol = eh->h_proto;
  82         skb->mac_header += VLAN_HLEN;
  83
  84         return skb;
  85 }
  86
  87 static struct sk_buff *modify_vlan_tci(struct datapath *dp, struct sk_buff *skb,
  88                                        const struct sw_flow_key *key,
  89                                        const struct nlattr *a, u32 actions_len)
  90 {
  91         __be16 tci = nla_get_be16(a);
  92         struct vlan_ethhdr *vh;
  93         __be16 old_tci;
  94
  95         if (vlan_tx_tag_present(skb) || skb->protocol != htons(ETH_P_8021Q))
  96                 return __vlan_hwaccel_put_tag(skb, ntohs(tci));
  97
  98         skb = make_writable(skb, 0);
  99         if (unlikely(!skb))
 100                 return NULL;
 101
 102         if (unlikely(skb->len < VLAN_ETH_HLEN))
 103                 return skb;
 104
 105         vh = vlan_eth_hdr(skb);
 106
 107         old_tci = vh->h_vlan_TCI;
 108         vh->h_vlan_TCI = tci;
 109
 110         if (get_ip_summed(skb) == OVS_CSUM_COMPLETE) {
 111                 __be16 diff[] = { ~old_tci, vh->h_vlan_TCI };
 112                 skb->csum = ~csum_partial((char *)diff, sizeof(diff), ~skb->csum);
 113         }
 114
 115         return skb;
 116 }
 117
 118 static bool is_ip(struct sk_buff *skb, const struct sw_flow_key *key)
 119 {
 120         return (key->dl_type == htons(ETH_P_IP) &&
 121                 skb->transport_header > skb->network_header);
 122 }
 123
 124 static __sum16 *get_l4_checksum(struct sk_buff *skb, const struct sw_flow_key *key)
 125 {
 126         int transport_len = skb->len - skb_transport_offset(skb);
 127         if (key->nw_proto == IPPROTO_TCP) {
 128                 if (likely(transport_len >= sizeof(struct tcphdr)))
 129                         return &tcp_hdr(skb)->check;
 130         } else if (key->nw_proto == IPPROTO_UDP) {
 131                 if (likely(transport_len >= sizeof(struct udphdr)))
 132                         return &udp_hdr(skb)->check;
 133         }
 134         return NULL;
 135 }
 136
 137 static struct sk_buff *set_nw_addr(struct sk_buff *skb,
 138                                    const struct sw_flow_key *key,
 139                                    const struct nlattr *a)
 140 {
 141         __be32 new_nwaddr = nla_get_be32(a);
 142         struct iphdr *nh;
 143         __sum16 *check;
 144         __be32 *nwaddr;
 145
 146         if (unlikely(!is_ip(skb, key)))
 147                 return skb;
 148
 149         skb = make_writable(skb, 0);
 150         if (unlikely(!skb))
 151                 return NULL;
 152
 153         nh = ip_hdr(skb);
 154         nwaddr = nla_type(a) == ODP_ACTION_ATTR_SET_NW_SRC ? &nh->saddr : &nh->daddr;
 155
 156         check = get_l4_checksum(skb, key);
 157         if (likely(check))
 158                 inet_proto_csum_replace4(check, skb, *nwaddr, new_nwaddr, 1);
 159         csum_replace4(&nh->check, *nwaddr, new_nwaddr);
 160
 161         *nwaddr = new_nwaddr;
 162
 163         return skb;
 164 }
 165
 166 static struct sk_buff *set_nw_tos(struct sk_buff *skb,
 167                                   const struct sw_flow_key *key,
 168                                   u8 nw_tos)
 169 {
 170         if (unlikely(!is_ip(skb, key)))
 171                 return skb;
 172
 173         skb = make_writable(skb, 0);
 174         if (skb) {
 175                 struct iphdr *nh = ip_hdr(skb);
 176                 u8 *f = &nh->tos;
 177                 u8 old = *f;
 178                 u8 new;
 179
 180                 /* Set the DSCP bits and preserve the ECN bits. */
 181                 new = nw_tos | (nh->tos & INET_ECN_MASK);
 182                 csum_replace4(&nh->check, (__force __be32)old,
 183                                           (__force __be32)new);
 184                 *f = new;
 185         }
 186         return skb;
 187 }
 188
 189 static struct sk_buff *set_tp_port(struct sk_buff *skb,
 190                                    const struct sw_flow_key *key,
 191                                    const struct nlattr *a)
 192 {
 193         struct udphdr *th;
 194         __sum16 *check;
 195         __be16 *port;
 196
 197         if (unlikely(!is_ip(skb, key)))
 198                 return skb;
 199
 200         skb = make_writable(skb, 0);
 201         if (unlikely(!skb))
 202                 return NULL;
 203
 204         /* Must follow make_writable() since that can move the skb data. */
 205         check = get_l4_checksum(skb, key);
 206         if (unlikely(!check))
 207                 return skb;
 208
 209         /*
 210          * Update port and checksum.
 211          *
 212          * This is OK because source and destination port numbers are at the
 213          * same offsets in both UDP and TCP headers, and get_l4_checksum() only
 214          * supports those protocols.
 215          */
 216         th = udp_hdr(skb);
 217         port = nla_type(a) == ODP_ACTION_ATTR_SET_TP_SRC ? &th->source : &th->dest;
 218         inet_proto_csum_replace2(check, skb, *port, nla_get_be16(a), 0);
 219         *port = nla_get_be16(a);
 220
 221         return skb;
 222 }
 223
 224 /**
 225  * is_spoofed_arp - check for invalid ARP packet
 226  *
 227  * @skb: skbuff containing an Ethernet packet, with network header pointing
 228  * just past the Ethernet and optional 802.1Q header.
 229  * @key: flow key extracted from @skb by flow_extract()
 230  *
 231  * Returns true if @skb is an invalid Ethernet+IPv4 ARP packet: one with screwy
 232  * or truncated header fields or one whose inner and outer Ethernet address
 233  * differ.
 234  */
 235 static bool is_spoofed_arp(struct sk_buff *skb, const struct sw_flow_key *key)
 236 {
 237         struct arp_eth_header *arp;
 238
 239         if (key->dl_type != htons(ETH_P_ARP))
 240                 return false;
 241
 242         if (skb_network_offset(skb) + sizeof(struct arp_eth_header) > skb->len)
 243                 return true;
 244
 245         arp = (struct arp_eth_header *)skb_network_header(skb);
 246         return (arp->ar_hrd != htons(ARPHRD_ETHER) ||
 247                 arp->ar_pro != htons(ETH_P_IP) ||
 248                 arp->ar_hln != ETH_ALEN ||
 249                 arp->ar_pln != 4 ||
 250                 compare_ether_addr(arp->ar_sha, eth_hdr(skb)->h_source));
 251 }
 252
 253 static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 254 {
 255         struct vport *p;
 256
 257         if (!skb)
 258                 goto error;
 259
 260         p = rcu_dereference(dp->ports[out_port]);
 261         if (!p)
 262                 goto error;
 263
 264         vport_send(p, skb);
 265         return;
 266
 267 error:
 268         kfree_skb(skb);
 269 }
 270
 271 static int output_control(struct datapath *dp, struct sk_buff *skb, u64 arg,
 272                           const struct sw_flow_key *key)
 273 {
 274         struct dp_upcall_info upcall;
 275
 276         skb = skb_clone(skb, GFP_ATOMIC);
 277         if (!skb)
 278                 return -ENOMEM;
 279
 280         upcall.cmd = ODP_PACKET_CMD_ACTION;
 281         upcall.key = key;
 282         upcall.userdata = arg;
 283         upcall.sample_pool = 0;
 284         upcall.actions = NULL;
 285         upcall.actions_len = 0;
 286         return dp_upcall(dp, skb, &upcall);
 287 }
 288
 289 /* Execute a list of actions against 'skb'. */
 290 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 291                               const struct sw_flow_key *key,
 292                               const struct nlattr *actions, u32 actions_len)
 293 {
 294         /* Every output action needs a separate clone of 'skb', but the common
 295          * case is just a single output action, so that doing a clone and
 296          * then freeing the original skbuff is wasteful.  So the following code
 297          * is slightly obscure just to avoid that. */
 298         int prev_port = -1;
 299         u32 priority = skb->priority;
 300         const struct nlattr *a;
 301         int rem, err;
 302
 303         for (a = actions, rem = actions_len; rem > 0; a = nla_next(a, &rem)) {
 304                 if (prev_port != -1) {
 305                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 306                         prev_port = -1;
 307                 }
 308
 309                 switch (nla_type(a)) {
 310                 case ODP_ACTION_ATTR_OUTPUT:
 311                         prev_port = nla_get_u32(a);
 312                         break;
 313
 314                 case ODP_ACTION_ATTR_CONTROLLER:
 315                         err = output_control(dp, skb, nla_get_u64(a), key);
 316                         if (err) {
 317                                 kfree_skb(skb);
 318                                 return err;
 319                         }
 320                         break;
 321
 322                 case ODP_ACTION_ATTR_SET_TUNNEL:
 323                         OVS_CB(skb)->tun_id = nla_get_be64(a);
 324                         break;
 325
 326                 case ODP_ACTION_ATTR_SET_DL_TCI:
 327                         skb = modify_vlan_tci(dp, skb, key, a, rem);
 328                         break;
 329
 330                 case ODP_ACTION_ATTR_STRIP_VLAN:
 331                         skb = strip_vlan(skb);
 332                         break;
 333
 334                 case ODP_ACTION_ATTR_SET_DL_SRC:
 335                         skb = make_writable(skb, 0);
 336                         if (!skb)
 337                                 return -ENOMEM;
 338                         memcpy(eth_hdr(skb)->h_source, nla_data(a), ETH_ALEN);
 339                         break;
 340
 341                 case ODP_ACTION_ATTR_SET_DL_DST:
 342                         skb = make_writable(skb, 0);
 343                         if (!skb)
 344                                 return -ENOMEM;
 345                         memcpy(eth_hdr(skb)->h_dest, nla_data(a), ETH_ALEN);
 346                         break;
 347
 348                 case ODP_ACTION_ATTR_SET_NW_SRC:
 349                 case ODP_ACTION_ATTR_SET_NW_DST:
 350                         skb = set_nw_addr(skb, key, a);
 351                         break;
 352
 353                 case ODP_ACTION_ATTR_SET_NW_TOS:
 354                         skb = set_nw_tos(skb, key, nla_get_u8(a));
 355                         break;
 356
 357                 case ODP_ACTION_ATTR_SET_TP_SRC:
 358                 case ODP_ACTION_ATTR_SET_TP_DST:
 359                         skb = set_tp_port(skb, key, a);
 360                         break;
 361
 362                 case ODP_ACTION_ATTR_SET_PRIORITY:
 363                         skb->priority = nla_get_u32(a);
 364                         break;
 365
 366                 case ODP_ACTION_ATTR_POP_PRIORITY:
 367                         skb->priority = priority;
 368                         break;
 369
 370                 case ODP_ACTION_ATTR_DROP_SPOOFED_ARP:
 371                         if (unlikely(is_spoofed_arp(skb, key)))
 372                                 goto exit;
 373                         break;
 374                 }
 375                 if (!skb)
 376                         return -ENOMEM;
 377         }
 378 exit:
 379         if (prev_port != -1)
 380                 do_output(dp, skb, prev_port);
 381         else
 382                 kfree_skb(skb);
 383         return 0;
 384 }
 385
 386 static void sflow_sample(struct datapath *dp, struct sk_buff *skb,
 387                          const struct sw_flow_key *key,
 388                          const struct nlattr *a, u32 actions_len)
 389 {
 390         struct sk_buff *nskb;
 391         struct vport *p = OVS_CB(skb)->vport;
 392         struct dp_upcall_info upcall;
 393
 394         if (unlikely(!p))
 395                 return;
 396
 397         atomic_inc(&p->sflow_pool);
 398         if (net_random() >= dp->sflow_probability)
 399                 return;
 400
 401         nskb = skb_clone(skb, GFP_ATOMIC);
 402         if (unlikely(!nskb))
 403                 return;
 404
 405         upcall.cmd = ODP_PACKET_CMD_SAMPLE;
 406         upcall.key = key;
 407         upcall.userdata = 0;
 408         upcall.sample_pool = atomic_read(&p->sflow_pool);
 409         upcall.actions = a;
 410         upcall.actions_len = actions_len;
 411         dp_upcall(dp, nskb, &upcall);
 412 }
 413
 414 /* Execute a list of actions against 'skb'. */
 415 int execute_actions(struct datapath *dp, struct sk_buff *skb,
 416                     const struct sw_flow_key *key,
 417                     const struct nlattr *actions, u32 actions_len)
 418 {
 419         if (dp->sflow_probability)
 420                 sflow_sample(dp, skb, key, actions, actions_len);
 421
 422         OVS_CB(skb)->tun_id = 0;
 423
 424         return do_execute_actions(dp, skb, key, actions, actions_len);
 425 }