net/openvswitch/actions.c

   1 /*
   2  * Copyright (c) 2007-2011 Nicira Networks.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301, USA
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/skbuff.h>
  22 #include <linux/in.h>
  23 #include <linux/ip.h>
  24 #include <linux/openvswitch.h>
  25 #include <linux/tcp.h>
  26 #include <linux/udp.h>
  27 #include <linux/in6.h>
  28 #include <linux/if_arp.h>
  29 #include <linux/if_vlan.h>
  30 #include <net/ip.h>
  31 #include <net/checksum.h>
  32 #include <net/dsfield.h>
  33
  34 #include "datapath.h"
  35 #include "vport.h"
  36
  37 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  38                         const struct nlattr *attr, int len, bool keep_skb);
  39
  40 static int make_writable(struct sk_buff *skb, int write_len)
  41 {
  42         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
  43                 return 0;
  44
  45         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  46 }
  47
  48 /* remove VLAN header from packet and update csum accrodingly. */
  49 static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
  50 {
  51         struct vlan_hdr *vhdr;
  52         int err;
  53
  54         err = make_writable(skb, VLAN_ETH_HLEN);
  55         if (unlikely(err))
  56                 return err;
  57
  58         if (skb->ip_summed == CHECKSUM_COMPLETE)
  59                 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
  60                                         + ETH_HLEN, VLAN_HLEN, 0));
  61
  62         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
  63         *current_tci = vhdr->h_vlan_TCI;
  64
  65         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
  66         __skb_pull(skb, VLAN_HLEN);
  67
  68         vlan_set_encap_proto(skb, vhdr);
  69         skb->mac_header += VLAN_HLEN;
  70         skb_reset_mac_len(skb);
  71
  72         return 0;
  73 }
  74
  75 static int pop_vlan(struct sk_buff *skb)
  76 {
  77         __be16 tci;
  78         int err;
  79
  80         if (likely(vlan_tx_tag_present(skb))) {
  81                 skb->vlan_tci = 0;
  82         } else {
  83                 if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
  84                              skb->len < VLAN_ETH_HLEN))
  85                         return 0;
  86
  87                 err = __pop_vlan_tci(skb, &tci);
  88                 if (err)
  89                         return err;
  90         }
  91         /* move next vlan tag to hw accel tag */
  92         if (likely(skb->protocol != htons(ETH_P_8021Q) ||
  93                    skb->len < VLAN_ETH_HLEN))
  94                 return 0;
  95
  96         err = __pop_vlan_tci(skb, &tci);
  97         if (unlikely(err))
  98                 return err;
  99
 100         __vlan_hwaccel_put_tag(skb, ntohs(tci));
 101         return 0;
 102 }
 103
 104 static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
 105 {
 106         if (unlikely(vlan_tx_tag_present(skb))) {
 107                 u16 current_tag;
 108
 109                 /* push down current VLAN tag */
 110                 current_tag = vlan_tx_tag_get(skb);
 111
 112                 if (!__vlan_put_tag(skb, current_tag))
 113                         return -ENOMEM;
 114
 115                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 116                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
 117                                         + ETH_HLEN, VLAN_HLEN, 0));
 118
 119         }
 120         __vlan_hwaccel_put_tag(skb, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
 121         return 0;
 122 }
 123
 124 static int set_eth_addr(struct sk_buff *skb,
 125                         const struct ovs_key_ethernet *eth_key)
 126 {
 127         int err;
 128         err = make_writable(skb, ETH_HLEN);
 129         if (unlikely(err))
 130                 return err;
 131
 132         memcpy(eth_hdr(skb)->h_source, eth_key->eth_src, ETH_ALEN);
 133         memcpy(eth_hdr(skb)->h_dest, eth_key->eth_dst, ETH_ALEN);
 134
 135         return 0;
 136 }
 137
 138 static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
 139                                 __be32 *addr, __be32 new_addr)
 140 {
 141         int transport_len = skb->len - skb_transport_offset(skb);
 142
 143         if (nh->protocol == IPPROTO_TCP) {
 144                 if (likely(transport_len >= sizeof(struct tcphdr)))
 145                         inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
 146                                                  *addr, new_addr, 1);
 147         } else if (nh->protocol == IPPROTO_UDP) {
 148                 if (likely(transport_len >= sizeof(struct udphdr)))
 149                         inet_proto_csum_replace4(&udp_hdr(skb)->check, skb,
 150                                                  *addr, new_addr, 1);
 151         }
 152
 153         csum_replace4(&nh->check, *addr, new_addr);
 154         skb->rxhash = 0;
 155         *addr = new_addr;
 156 }
 157
 158 static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
 159 {
 160         csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
 161         nh->ttl = new_ttl;
 162 }
 163
 164 static int set_ipv4(struct sk_buff *skb, const struct ovs_key_ipv4 *ipv4_key)
 165 {
 166         struct iphdr *nh;
 167         int err;
 168
 169         err = make_writable(skb, skb_network_offset(skb) +
 170                                  sizeof(struct iphdr));
 171         if (unlikely(err))
 172                 return err;
 173
 174         nh = ip_hdr(skb);
 175
 176         if (ipv4_key->ipv4_src != nh->saddr)
 177                 set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
 178
 179         if (ipv4_key->ipv4_dst != nh->daddr)
 180                 set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
 181
 182         if (ipv4_key->ipv4_tos != nh->tos)
 183                 ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
 184
 185         if (ipv4_key->ipv4_ttl != nh->ttl)
 186                 set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
 187
 188         return 0;
 189 }
 190
 191 /* Must follow make_writable() since that can move the skb data. */
 192 static void set_tp_port(struct sk_buff *skb, __be16 *port,
 193                          __be16 new_port, __sum16 *check)
 194 {
 195         inet_proto_csum_replace2(check, skb, *port, new_port, 0);
 196         *port = new_port;
 197         skb->rxhash = 0;
 198 }
 199
 200 static int set_udp_port(struct sk_buff *skb,
 201                         const struct ovs_key_udp *udp_port_key)
 202 {
 203         struct udphdr *uh;
 204         int err;
 205
 206         err = make_writable(skb, skb_transport_offset(skb) +
 207                                  sizeof(struct udphdr));
 208         if (unlikely(err))
 209                 return err;
 210
 211         uh = udp_hdr(skb);
 212         if (udp_port_key->udp_src != uh->source)
 213                 set_tp_port(skb, &uh->source, udp_port_key->udp_src, &uh->check);
 214
 215         if (udp_port_key->udp_dst != uh->dest)
 216                 set_tp_port(skb, &uh->dest, udp_port_key->udp_dst, &uh->check);
 217
 218         return 0;
 219 }
 220
 221 static int set_tcp_port(struct sk_buff *skb,
 222                         const struct ovs_key_tcp *tcp_port_key)
 223 {
 224         struct tcphdr *th;
 225         int err;
 226
 227         err = make_writable(skb, skb_transport_offset(skb) +
 228                                  sizeof(struct tcphdr));
 229         if (unlikely(err))
 230                 return err;
 231
 232         th = tcp_hdr(skb);
 233         if (tcp_port_key->tcp_src != th->source)
 234                 set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
 235
 236         if (tcp_port_key->tcp_dst != th->dest)
 237                 set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
 238
 239         return 0;
 240 }
 241
 242 static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 243 {
 244         struct vport *vport;
 245
 246         if (unlikely(!skb))
 247                 return -ENOMEM;
 248
 249         vport = rcu_dereference(dp->ports[out_port]);
 250         if (unlikely(!vport)) {
 251                 kfree_skb(skb);
 252                 return -ENODEV;
 253         }
 254
 255         ovs_vport_send(vport, skb);
 256         return 0;
 257 }
 258
 259 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 260                             const struct nlattr *attr)
 261 {
 262         struct dp_upcall_info upcall;
 263         const struct nlattr *a;
 264         int rem;
 265
 266         upcall.cmd = OVS_PACKET_CMD_ACTION;
 267         upcall.key = &OVS_CB(skb)->flow->key;
 268         upcall.userdata = NULL;
 269         upcall.pid = 0;
 270
 271         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 272                  a = nla_next(a, &rem)) {
 273                 switch (nla_type(a)) {
 274                 case OVS_USERSPACE_ATTR_USERDATA:
 275                         upcall.userdata = a;
 276                         break;
 277
 278                 case OVS_USERSPACE_ATTR_PID:
 279                         upcall.pid = nla_get_u32(a);
 280                         break;
 281                 }
 282         }
 283
 284         return ovs_dp_upcall(dp, skb, &upcall);
 285 }
 286
 287 static int sample(struct datapath *dp, struct sk_buff *skb,
 288                   const struct nlattr *attr)
 289 {
 290         const struct nlattr *acts_list = NULL;
 291         const struct nlattr *a;
 292         int rem;
 293
 294         for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 295                  a = nla_next(a, &rem)) {
 296                 switch (nla_type(a)) {
 297                 case OVS_SAMPLE_ATTR_PROBABILITY:
 298                         if (net_random() >= nla_get_u32(a))
 299                                 return 0;
 300                         break;
 301
 302                 case OVS_SAMPLE_ATTR_ACTIONS:
 303                         acts_list = a;
 304                         break;
 305                 }
 306         }
 307
 308         return do_execute_actions(dp, skb, nla_data(acts_list),
 309                                                  nla_len(acts_list), true);
 310 }
 311
 312 static int execute_set_action(struct sk_buff *skb,
 313                                  const struct nlattr *nested_attr)
 314 {
 315         int err = 0;
 316
 317         switch (nla_type(nested_attr)) {
 318         case OVS_KEY_ATTR_PRIORITY:
 319                 skb->priority = nla_get_u32(nested_attr);
 320                 break;
 321
 322         case OVS_KEY_ATTR_ETHERNET:
 323                 err = set_eth_addr(skb, nla_data(nested_attr));
 324                 break;
 325
 326         case OVS_KEY_ATTR_IPV4:
 327                 err = set_ipv4(skb, nla_data(nested_attr));
 328                 break;
 329
 330         case OVS_KEY_ATTR_TCP:
 331                 err = set_tcp_port(skb, nla_data(nested_attr));
 332                 break;
 333
 334         case OVS_KEY_ATTR_UDP:
 335                 err = set_udp_port(skb, nla_data(nested_attr));
 336                 break;
 337         }
 338
 339         return err;
 340 }
 341
 342 /* Execute a list of actions against 'skb'. */
 343 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 344                         const struct nlattr *attr, int len, bool keep_skb)
 345 {
 346         /* Every output action needs a separate clone of 'skb', but the common
 347          * case is just a single output action, so that doing a clone and
 348          * then freeing the original skbuff is wasteful.  So the following code
 349          * is slightly obscure just to avoid that. */
 350         int prev_port = -1;
 351         const struct nlattr *a;
 352         int rem;
 353
 354         for (a = attr, rem = len; rem > 0;
 355              a = nla_next(a, &rem)) {
 356                 int err = 0;
 357
 358                 if (prev_port != -1) {
 359                         do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 360                         prev_port = -1;
 361                 }
 362
 363                 switch (nla_type(a)) {
 364                 case OVS_ACTION_ATTR_OUTPUT:
 365                         prev_port = nla_get_u32(a);
 366                         break;
 367
 368                 case OVS_ACTION_ATTR_USERSPACE:
 369                         output_userspace(dp, skb, a);
 370                         break;
 371
 372                 case OVS_ACTION_ATTR_PUSH_VLAN:
 373                         err = push_vlan(skb, nla_data(a));
 374                         if (unlikely(err)) /* skb already freed. */
 375                                 return err;
 376                         break;
 377
 378                 case OVS_ACTION_ATTR_POP_VLAN:
 379                         err = pop_vlan(skb);
 380                         break;
 381
 382                 case OVS_ACTION_ATTR_SET:
 383                         err = execute_set_action(skb, nla_data(a));
 384                         break;
 385
 386                 case OVS_ACTION_ATTR_SAMPLE:
 387                         err = sample(dp, skb, a);
 388                         break;
 389                 }
 390
 391                 if (unlikely(err)) {
 392                         kfree_skb(skb);
 393                         return err;
 394                 }
 395         }
 396
 397         if (prev_port != -1) {
 398                 if (keep_skb)
 399                         skb = skb_clone(skb, GFP_ATOMIC);
 400
 401                 do_output(dp, skb, prev_port);
 402         } else if (!keep_skb)
 403                 consume_skb(skb);
 404
 405         return 0;
 406 }
 407
 408 /* Execute a list of actions against 'skb'. */
 409 int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb)
 410 {
 411         struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 412
 413         return do_execute_actions(dp, skb, acts->actions,
 414                                          acts->actions_len, false);
 415 }