linux/net/openvswitch/actions.c
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   1/*
   2 * Copyright (c) 2007-2012 Nicira, Inc.
   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
  37static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  38                        const struct nlattr *attr, int len, bool keep_skb);
  39
  40static 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 accordingly. */
  49static 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
  75static 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
 104static 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
 124static 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
 138static 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                        struct udphdr *uh = udp_hdr(skb);
 150
 151                        if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
 152                                inet_proto_csum_replace4(&uh->check, skb,
 153                                                         *addr, new_addr, 1);
 154                                if (!uh->check)
 155                                        uh->check = CSUM_MANGLED_0;
 156                        }
 157                }
 158        }
 159
 160        csum_replace4(&nh->check, *addr, new_addr);
 161        skb->rxhash = 0;
 162        *addr = new_addr;
 163}
 164
 165static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
 166{
 167        csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
 168        nh->ttl = new_ttl;
 169}
 170
 171static int set_ipv4(struct sk_buff *skb, const struct ovs_key_ipv4 *ipv4_key)
 172{
 173        struct iphdr *nh;
 174        int err;
 175
 176        err = make_writable(skb, skb_network_offset(skb) +
 177                                 sizeof(struct iphdr));
 178        if (unlikely(err))
 179                return err;
 180
 181        nh = ip_hdr(skb);
 182
 183        if (ipv4_key->ipv4_src != nh->saddr)
 184                set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
 185
 186        if (ipv4_key->ipv4_dst != nh->daddr)
 187                set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
 188
 189        if (ipv4_key->ipv4_tos != nh->tos)
 190                ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
 191
 192        if (ipv4_key->ipv4_ttl != nh->ttl)
 193                set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
 194
 195        return 0;
 196}
 197
 198/* Must follow make_writable() since that can move the skb data. */
 199static void set_tp_port(struct sk_buff *skb, __be16 *port,
 200                         __be16 new_port, __sum16 *check)
 201{
 202        inet_proto_csum_replace2(check, skb, *port, new_port, 0);
 203        *port = new_port;
 204        skb->rxhash = 0;
 205}
 206
 207static void set_udp_port(struct sk_buff *skb, __be16 *port, __be16 new_port)
 208{
 209        struct udphdr *uh = udp_hdr(skb);
 210
 211        if (uh->check && skb->ip_summed != CHECKSUM_PARTIAL) {
 212                set_tp_port(skb, port, new_port, &uh->check);
 213
 214                if (!uh->check)
 215                        uh->check = CSUM_MANGLED_0;
 216        } else {
 217                *port = new_port;
 218                skb->rxhash = 0;
 219        }
 220}
 221
 222static int set_udp(struct sk_buff *skb, const struct ovs_key_udp *udp_port_key)
 223{
 224        struct udphdr *uh;
 225        int err;
 226
 227        err = make_writable(skb, skb_transport_offset(skb) +
 228                                 sizeof(struct udphdr));
 229        if (unlikely(err))
 230                return err;
 231
 232        uh = udp_hdr(skb);
 233        if (udp_port_key->udp_src != uh->source)
 234                set_udp_port(skb, &uh->source, udp_port_key->udp_src);
 235
 236        if (udp_port_key->udp_dst != uh->dest)
 237                set_udp_port(skb, &uh->dest, udp_port_key->udp_dst);
 238
 239        return 0;
 240}
 241
 242static int set_tcp(struct sk_buff *skb, const struct ovs_key_tcp *tcp_port_key)
 243{
 244        struct tcphdr *th;
 245        int err;
 246
 247        err = make_writable(skb, skb_transport_offset(skb) +
 248                                 sizeof(struct tcphdr));
 249        if (unlikely(err))
 250                return err;
 251
 252        th = tcp_hdr(skb);
 253        if (tcp_port_key->tcp_src != th->source)
 254                set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
 255
 256        if (tcp_port_key->tcp_dst != th->dest)
 257                set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
 258
 259        return 0;
 260}
 261
 262static int do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 263{
 264        struct vport *vport;
 265
 266        if (unlikely(!skb))
 267                return -ENOMEM;
 268
 269        vport = rcu_dereference(dp->ports[out_port]);
 270        if (unlikely(!vport)) {
 271                kfree_skb(skb);
 272                return -ENODEV;
 273        }
 274
 275        ovs_vport_send(vport, skb);
 276        return 0;
 277}
 278
 279static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 280                            const struct nlattr *attr)
 281{
 282        struct dp_upcall_info upcall;
 283        const struct nlattr *a;
 284        int rem;
 285
 286        upcall.cmd = OVS_PACKET_CMD_ACTION;
 287        upcall.key = &OVS_CB(skb)->flow->key;
 288        upcall.userdata = NULL;
 289        upcall.pid = 0;
 290
 291        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 292                 a = nla_next(a, &rem)) {
 293                switch (nla_type(a)) {
 294                case OVS_USERSPACE_ATTR_USERDATA:
 295                        upcall.userdata = a;
 296                        break;
 297
 298                case OVS_USERSPACE_ATTR_PID:
 299                        upcall.pid = nla_get_u32(a);
 300                        break;
 301                }
 302        }
 303
 304        return ovs_dp_upcall(dp, skb, &upcall);
 305}
 306
 307static int sample(struct datapath *dp, struct sk_buff *skb,
 308                  const struct nlattr *attr)
 309{
 310        const struct nlattr *acts_list = NULL;
 311        const struct nlattr *a;
 312        int rem;
 313
 314        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 315                 a = nla_next(a, &rem)) {
 316                switch (nla_type(a)) {
 317                case OVS_SAMPLE_ATTR_PROBABILITY:
 318                        if (net_random() >= nla_get_u32(a))
 319                                return 0;
 320                        break;
 321
 322                case OVS_SAMPLE_ATTR_ACTIONS:
 323                        acts_list = a;
 324                        break;
 325                }
 326        }
 327
 328        return do_execute_actions(dp, skb, nla_data(acts_list),
 329                                                 nla_len(acts_list), true);
 330}
 331
 332static int execute_set_action(struct sk_buff *skb,
 333                                 const struct nlattr *nested_attr)
 334{
 335        int err = 0;
 336
 337        switch (nla_type(nested_attr)) {
 338        case OVS_KEY_ATTR_PRIORITY:
 339                skb->priority = nla_get_u32(nested_attr);
 340                break;
 341
 342        case OVS_KEY_ATTR_ETHERNET:
 343                err = set_eth_addr(skb, nla_data(nested_attr));
 344                break;
 345
 346        case OVS_KEY_ATTR_IPV4:
 347                err = set_ipv4(skb, nla_data(nested_attr));
 348                break;
 349
 350        case OVS_KEY_ATTR_TCP:
 351                err = set_tcp(skb, nla_data(nested_attr));
 352                break;
 353
 354        case OVS_KEY_ATTR_UDP:
 355                err = set_udp(skb, nla_data(nested_attr));
 356                break;
 357        }
 358
 359        return err;
 360}
 361
 362/* Execute a list of actions against 'skb'. */
 363static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 364                        const struct nlattr *attr, int len, bool keep_skb)
 365{
 366        /* Every output action needs a separate clone of 'skb', but the common
 367         * case is just a single output action, so that doing a clone and
 368         * then freeing the original skbuff is wasteful.  So the following code
 369         * is slightly obscure just to avoid that. */
 370        int prev_port = -1;
 371        const struct nlattr *a;
 372        int rem;
 373
 374        for (a = attr, rem = len; rem > 0;
 375             a = nla_next(a, &rem)) {
 376                int err = 0;
 377
 378                if (prev_port != -1) {
 379                        do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
 380                        prev_port = -1;
 381                }
 382
 383                switch (nla_type(a)) {
 384                case OVS_ACTION_ATTR_OUTPUT:
 385                        prev_port = nla_get_u32(a);
 386                        break;
 387
 388                case OVS_ACTION_ATTR_USERSPACE:
 389                        output_userspace(dp, skb, a);
 390                        break;
 391
 392                case OVS_ACTION_ATTR_PUSH_VLAN:
 393                        err = push_vlan(skb, nla_data(a));
 394                        if (unlikely(err)) /* skb already freed. */
 395                                return err;
 396                        break;
 397
 398                case OVS_ACTION_ATTR_POP_VLAN:
 399                        err = pop_vlan(skb);
 400                        break;
 401
 402                case OVS_ACTION_ATTR_SET:
 403                        err = execute_set_action(skb, nla_data(a));
 404                        break;
 405
 406                case OVS_ACTION_ATTR_SAMPLE:
 407                        err = sample(dp, skb, a);
 408                        break;
 409                }
 410
 411                if (unlikely(err)) {
 412                        kfree_skb(skb);
 413                        return err;
 414                }
 415        }
 416
 417        if (prev_port != -1) {
 418                if (keep_skb)
 419                        skb = skb_clone(skb, GFP_ATOMIC);
 420
 421                do_output(dp, skb, prev_port);
 422        } else if (!keep_skb)
 423                consume_skb(skb);
 424
 425        return 0;
 426}
 427
 428/* Execute a list of actions against 'skb'. */
 429int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb)
 430{
 431        struct sw_flow_actions *acts = rcu_dereference(OVS_CB(skb)->flow->sf_acts);
 432
 433        return do_execute_actions(dp, skb, acts->actions,
 434                                         acts->actions_len, false);
 435}
 436
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