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 "loop_counter.h"
  27 #include "openvswitch/datapath-protocol.h"
  28 #include "vlan.h"
  29 #include "vport.h"
  30
  31 static int do_execute_actions(struct datapath *, struct sk_buff *,
  32                               struct sw_flow_actions *acts);
  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 sk_buff *skb, __be16 tci)
  88 {
  89         struct vlan_ethhdr *vh;
  90         __be16 old_tci;
  91
  92         if (vlan_tx_tag_present(skb) || skb->protocol != htons(ETH_P_8021Q))
  93                 return __vlan_hwaccel_put_tag(skb, ntohs(tci));
  94
  95         skb = make_writable(skb, 0);
  96         if (unlikely(!skb))
  97                 return NULL;
  98
  99         if (unlikely(skb->len < VLAN_ETH_HLEN))
 100                 return skb;
 101
 102         vh = vlan_eth_hdr(skb);
 103
 104         old_tci = vh->h_vlan_TCI;
 105         vh->h_vlan_TCI = tci;
 106
 107         if (get_ip_summed(skb) == OVS_CSUM_COMPLETE) {
 108                 __be16 diff[] = { ~old_tci, vh->h_vlan_TCI };
 109                 skb->csum = ~csum_partial((char *)diff, sizeof(diff), ~skb->csum);
 110         }
 111
 112         return skb;
 113 }
 114
 115 static bool is_ip(struct sk_buff *skb)
 116 {
 117         return (OVS_CB(skb)->flow->key.eth.type == htons(ETH_P_IP) &&
 118                 skb->transport_header > skb->network_header);
 119 }
 120
 121 static __sum16 *get_l4_checksum(struct sk_buff *skb)
 122 {
 123         u8 nw_proto = OVS_CB(skb)->flow->key.ip.proto;
 124         int transport_len = skb->len - skb_transport_offset(skb);
 125         if (nw_proto == IPPROTO_TCP) {
 126                 if (likely(transport_len >= sizeof(struct tcphdr)))
 127                         return &tcp_hdr(skb)->check;
 128         } else if (nw_proto == IPPROTO_UDP) {
 129                 if (likely(transport_len >= sizeof(struct udphdr)))
 130                         return &udp_hdr(skb)->check;
 131         }
 132         return NULL;
 133 }
 134
 135 static struct sk_buff *set_nw_addr(struct sk_buff *skb, const struct nlattr *a)
 136 {
 137         __be32 new_nwaddr = nla_get_be32(a);
 138         struct iphdr *nh;
 139         __sum16 *check;
 140         __be32 *nwaddr;
 141
 142         if (unlikely(!is_ip(skb)))
 143                 return skb;
 144
 145         skb = make_writable(skb, 0);
 146         if (unlikely(!skb))
 147                 return NULL;
 148
 149         nh = ip_hdr(skb);
 150         nwaddr = nla_type(a) == ODP_ACTION_ATTR_SET_NW_SRC ? &nh->saddr : &nh->daddr;
 151
 152         check = get_l4_checksum(skb);
 153         if (likely(check))
 154                 inet_proto_csum_replace4(check, skb, *nwaddr, new_nwaddr, 1);
 155         csum_replace4(&nh->check, *nwaddr, new_nwaddr);
 156
 157         skb_clear_rxhash(skb);
 158
 159         *nwaddr = new_nwaddr;
 160
 161         return skb;
 162 }
 163
 164 static struct sk_buff *set_nw_tos(struct sk_buff *skb, u8 nw_tos)
 165 {
 166         if (unlikely(!is_ip(skb)))
 167                 return skb;
 168
 169         skb = make_writable(skb, 0);
 170         if (skb) {
 171                 struct iphdr *nh = ip_hdr(skb);
 172                 u8 *f = &nh->tos;
 173                 u8 old = *f;
 174                 u8 new;
 175
 176                 /* Set the DSCP bits and preserve the ECN bits. */
 177                 new = nw_tos | (nh->tos & INET_ECN_MASK);
 178                 csum_replace4(&nh->check, (__force __be32)old,
 179                                           (__force __be32)new);
 180                 *f = new;
 181         }
 182         return skb;
 183 }
 184
 185 static struct sk_buff *set_tp_port(struct sk_buff *skb, const struct nlattr *a)
 186 {
 187         struct udphdr *th;
 188         __sum16 *check;
 189         __be16 *port;
 190
 191         if (unlikely(!is_ip(skb)))
 192                 return skb;
 193
 194         skb = make_writable(skb, 0);
 195         if (unlikely(!skb))
 196                 return NULL;
 197
 198         /* Must follow make_writable() since that can move the skb data. */
 199         check = get_l4_checksum(skb);
 200         if (unlikely(!check))
 201                 return skb;
 202
 203         /*
 204          * Update port and checksum.
 205          *
 206          * This is OK because source and destination port numbers are at the
 207          * same offsets in both UDP and TCP headers, and get_l4_checksum() only
 208          * supports those protocols.
 209          */
 210         th = udp_hdr(skb);
 211         port = nla_type(a) == ODP_ACTION_ATTR_SET_TP_SRC ? &th->source : &th->dest;
 212         inet_proto_csum_replace2(check, skb, *port, nla_get_be16(a), 0);
 213         *port = nla_get_be16(a);
 214         skb_clear_rxhash(skb);
 215
 216         return skb;
 217 }
 218
 219 static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 220 {
 221         struct vport *p;
 222
 223         if (!skb)
 224                 goto error;
 225
 226         p = rcu_dereference(dp->ports[out_port]);
 227         if (!p)
 228                 goto error;
 229
 230         vport_send(p, skb);
 231         return;
 232
 233 error:
 234         kfree_skb(skb);
 235 }
 236
 237 static int output_control(struct datapath *dp, struct sk_buff *skb, u64 arg)
 238 {
 239         struct dp_upcall_info upcall;
 240
 241         skb = skb_clone(skb, GFP_ATOMIC);
 242         if (!skb)
 243                 return -ENOMEM;
 244
 245         upcall.cmd = ODP_PACKET_CMD_ACTION;
 246         upcall.key = &OVS_CB(skb)->flow->key;
 247         upcall.userdata = arg;
 248         upcall.sample_pool = 0;
 249         upcall.actions = NULL;
 250         upcall.actions_len = 0;
 251         return dp_upcall(dp, skb, &upcall);
 252 }
 253
 254 /* Execute a list of actions against 'skb'. */
 255 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 256                               struct sw_flow_actions *acts)
 257 {
 258         /* Every output action needs a separate clone of 'skb', but the common
 259          * case is just a single output action, so that doing a clone and
 260          * then freeing the original skbuff is wasteful.  So the following code
 261          * is slightly obscure just to avoid that. */
 262         int prev_port = -1;
 263         u32 priority = skb->priority;
 264         const struct nlattr *a;
 265         int rem, err;
 266
 267         for (a = acts->actions, rem = acts->actions_len; rem > 0;
 268              a = nla_next(a, &rem)) {
 269                 if (prev_port != -1) {
 270                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 271                         prev_port = -1;
 272                 }
 273
 274                 switch (nla_type(a)) {
 275                 case ODP_ACTION_ATTR_OUTPUT:
 276                         prev_port = nla_get_u32(a);
 277                         break;
 278
 279                 case ODP_ACTION_ATTR_CONTROLLER:
 280                         err = output_control(dp, skb, nla_get_u64(a));
 281                         if (err) {
 282                                 kfree_skb(skb);
 283                                 return err;
 284                         }
 285                         break;
 286
 287                 case ODP_ACTION_ATTR_SET_TUNNEL:
 288                         OVS_CB(skb)->tun_id = nla_get_be64(a);
 289                         break;
 290
 291                 case ODP_ACTION_ATTR_SET_DL_TCI:
 292                         skb = modify_vlan_tci(skb, nla_get_be16(a));
 293                         break;
 294
 295                 case ODP_ACTION_ATTR_STRIP_VLAN:
 296                         skb = strip_vlan(skb);
 297                         break;
 298
 299                 case ODP_ACTION_ATTR_SET_DL_SRC:
 300                         skb = make_writable(skb, 0);
 301                         if (!skb)
 302                                 return -ENOMEM;
 303                         memcpy(eth_hdr(skb)->h_source, nla_data(a), ETH_ALEN);
 304                         break;
 305
 306                 case ODP_ACTION_ATTR_SET_DL_DST:
 307                         skb = make_writable(skb, 0);
 308                         if (!skb)
 309                                 return -ENOMEM;
 310                         memcpy(eth_hdr(skb)->h_dest, nla_data(a), ETH_ALEN);
 311                         break;
 312
 313                 case ODP_ACTION_ATTR_SET_NW_SRC:
 314                 case ODP_ACTION_ATTR_SET_NW_DST:
 315                         skb = set_nw_addr(skb, a);
 316                         break;
 317
 318                 case ODP_ACTION_ATTR_SET_NW_TOS:
 319                         skb = set_nw_tos(skb, nla_get_u8(a));
 320                         break;
 321
 322                 case ODP_ACTION_ATTR_SET_TP_SRC:
 323                 case ODP_ACTION_ATTR_SET_TP_DST:
 324                         skb = set_tp_port(skb, a);
 325                         break;
 326
 327                 case ODP_ACTION_ATTR_SET_PRIORITY:
 328                         skb->priority = nla_get_u32(a);
 329                         break;
 330
 331                 case ODP_ACTION_ATTR_POP_PRIORITY:
 332                         skb->priority = priority;
 333                         break;
 334                 }
 335                 if (!skb)
 336                         return -ENOMEM;
 337         }
 338
 339         if (prev_port != -1)
 340                 do_output(dp, skb, prev_port);
 341         else
 342                 kfree_skb(skb);
 343         return 0;
 344 }
 345
 346 static void sflow_sample(struct datapath *dp, struct sk_buff *skb,
 347                          struct sw_flow_actions *acts)
 348 {
 349         struct sk_buff *nskb;
 350         struct vport *p = OVS_CB(skb)->vport;
 351         struct dp_upcall_info upcall;
 352
 353         if (unlikely(!p))
 354                 return;
 355
 356         atomic_inc(&p->sflow_pool);
 357         if (net_random() >= dp->sflow_probability)
 358                 return;
 359
 360         nskb = skb_clone(skb, GFP_ATOMIC);
 361         if (unlikely(!nskb))
 362                 return;
 363
 364         upcall.cmd = ODP_PACKET_CMD_SAMPLE;
 365         upcall.key = &OVS_CB(skb)->flow->key;
 366         upcall.userdata = 0;
 367         upcall.sample_pool = atomic_read(&p->sflow_pool);
 368         upcall.actions = acts->actions;
 369         upcall.actions_len = acts->actions_len;
 370         dp_upcall(dp, nskb, &upcall);
 371 }
 372
 373 /* Execute a list of actions against 'skb'. */
 374 int execute_actions(struct datapath *dp, struct sk_buff *skb)
 375 {
 376         struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 377         struct loop_counter *loop;
 378         int error;
 379
 380         /* Check whether we've looped too much. */
 381         loop = loop_get_counter();
 382         if (unlikely(++loop->count > MAX_LOOPS))
 383                 loop->looping = true;
 384         if (unlikely(loop->looping)) {
 385                 error = loop_suppress(dp, acts);
 386                 kfree_skb(skb);
 387                 goto out_loop;
 388         }
 389
 390         /* Really execute actions. */
 391         if (dp->sflow_probability)
 392                 sflow_sample(dp, skb, acts);
 393         OVS_CB(skb)->tun_id = 0;
 394         error = do_execute_actions(dp, skb, acts);
 395
 396         /* Check whether sub-actions looped too much. */
 397         if (unlikely(loop->looping))
 398                 error = loop_suppress(dp, acts);
 399
 400 out_loop:
 401         /* Decrement loop counter. */
 402         if (!--loop->count)
 403                 loop->looping = false;
 404         loop_put_counter();
 405
 406         return error;
 407 }