net/sched/act_mirred.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/act_mirred.c       packet mirroring and redirect actions
   4  *
   5  * Authors:     Jamal Hadi Salim (2002-4)
   6  *
   7  * TODO: Add ingress support (and socket redirect support)
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/rtnetlink.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/gfp.h>
  19 #include <linux/if_arp.h>
  20 #include <net/net_namespace.h>
  21 #include <net/netlink.h>
  22 #include <net/dst.h>
  23 #include <net/pkt_sched.h>
  24 #include <net/pkt_cls.h>
  25 #include <linux/tc_act/tc_mirred.h>
  26 #include <net/tc_act/tc_mirred.h>
  27 #include <net/tc_wrapper.h>
  28
  29 static LIST_HEAD(mirred_list);
  30 static DEFINE_SPINLOCK(mirred_list_lock);
  31
  32 #define MIRRED_NEST_LIMIT    4
  33 static DEFINE_PER_CPU(unsigned int, mirred_nest_level);
  34
  35 static bool tcf_mirred_is_act_redirect(int action)
  36 {
  37         return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  38 }
  39
  40 static bool tcf_mirred_act_wants_ingress(int action)
  41 {
  42         switch (action) {
  43         case TCA_EGRESS_REDIR:
  44         case TCA_EGRESS_MIRROR:
  45                 return false;
  46         case TCA_INGRESS_REDIR:
  47         case TCA_INGRESS_MIRROR:
  48                 return true;
  49         default:
  50                 BUG();
  51         }
  52 }
  53
  54 static bool tcf_mirred_can_reinsert(int action)
  55 {
  56         switch (action) {
  57         case TC_ACT_SHOT:
  58         case TC_ACT_STOLEN:
  59         case TC_ACT_QUEUED:
  60         case TC_ACT_TRAP:
  61                 return true;
  62         }
  63         return false;
  64 }
  65
  66 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
  67 {
  68         return rcu_dereference_protected(m->tcfm_dev,
  69                                          lockdep_is_held(&m->tcf_lock));
  70 }
  71
  72 static void tcf_mirred_release(struct tc_action *a)
  73 {
  74         struct tcf_mirred *m = to_mirred(a);
  75         struct net_device *dev;
  76
  77         spin_lock(&mirred_list_lock);
  78         list_del(&m->tcfm_list);
  79         spin_unlock(&mirred_list_lock);
  80
  81         /* last reference to action, no need to lock */
  82         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  83         netdev_put(dev, &m->tcfm_dev_tracker);
  84 }
  85
  86 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  87         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  88 };
  89
  90 static struct tc_action_ops act_mirred_ops;
  91
  92 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  93                            struct nlattr *est, struct tc_action **a,
  94                            struct tcf_proto *tp,
  95                            u32 flags, struct netlink_ext_ack *extack)
  96 {
  97         struct tc_action_net *tn = net_generic(net, act_mirred_ops.net_id);
  98         bool bind = flags & TCA_ACT_FLAGS_BIND;
  99         struct nlattr *tb[TCA_MIRRED_MAX + 1];
 100         struct tcf_chain *goto_ch = NULL;
 101         bool mac_header_xmit = false;
 102         struct tc_mirred *parm;
 103         struct tcf_mirred *m;
 104         bool exists = false;
 105         int ret, err;
 106         u32 index;
 107
 108         if (!nla) {
 109                 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
 110                 return -EINVAL;
 111         }
 112         ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
 113                                           mirred_policy, extack);
 114         if (ret < 0)
 115                 return ret;
 116         if (!tb[TCA_MIRRED_PARMS]) {
 117                 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
 118                 return -EINVAL;
 119         }
 120         parm = nla_data(tb[TCA_MIRRED_PARMS]);
 121         index = parm->index;
 122         err = tcf_idr_check_alloc(tn, &index, a, bind);
 123         if (err < 0)
 124                 return err;
 125         exists = err;
 126         if (exists && bind)
 127                 return 0;
 128
 129         switch (parm->eaction) {
 130         case TCA_EGRESS_MIRROR:
 131         case TCA_EGRESS_REDIR:
 132         case TCA_INGRESS_REDIR:
 133         case TCA_INGRESS_MIRROR:
 134                 break;
 135         default:
 136                 if (exists)
 137                         tcf_idr_release(*a, bind);
 138                 else
 139                         tcf_idr_cleanup(tn, index);
 140                 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 141                 return -EINVAL;
 142         }
 143
 144         if (!exists) {
 145                 if (!parm->ifindex) {
 146                         tcf_idr_cleanup(tn, index);
 147                         NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 148                         return -EINVAL;
 149                 }
 150                 ret = tcf_idr_create_from_flags(tn, index, est, a,
 151                                                 &act_mirred_ops, bind, flags);
 152                 if (ret) {
 153                         tcf_idr_cleanup(tn, index);
 154                         return ret;
 155                 }
 156                 ret = ACT_P_CREATED;
 157         } else if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 158                 tcf_idr_release(*a, bind);
 159                 return -EEXIST;
 160         }
 161
 162         m = to_mirred(*a);
 163         if (ret == ACT_P_CREATED)
 164                 INIT_LIST_HEAD(&m->tcfm_list);
 165
 166         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 167         if (err < 0)
 168                 goto release_idr;
 169
 170         spin_lock_bh(&m->tcf_lock);
 171
 172         if (parm->ifindex) {
 173                 struct net_device *odev, *ndev;
 174
 175                 ndev = dev_get_by_index(net, parm->ifindex);
 176                 if (!ndev) {
 177                         spin_unlock_bh(&m->tcf_lock);
 178                         err = -ENODEV;
 179                         goto put_chain;
 180                 }
 181                 mac_header_xmit = dev_is_mac_header_xmit(ndev);
 182                 odev = rcu_replace_pointer(m->tcfm_dev, ndev,
 183                                           lockdep_is_held(&m->tcf_lock));
 184                 netdev_put(odev, &m->tcfm_dev_tracker);
 185                 netdev_tracker_alloc(ndev, &m->tcfm_dev_tracker, GFP_ATOMIC);
 186                 m->tcfm_mac_header_xmit = mac_header_xmit;
 187         }
 188         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 189         m->tcfm_eaction = parm->eaction;
 190         spin_unlock_bh(&m->tcf_lock);
 191         if (goto_ch)
 192                 tcf_chain_put_by_act(goto_ch);
 193
 194         if (ret == ACT_P_CREATED) {
 195                 spin_lock(&mirred_list_lock);
 196                 list_add(&m->tcfm_list, &mirred_list);
 197                 spin_unlock(&mirred_list_lock);
 198         }
 199
 200         return ret;
 201 put_chain:
 202         if (goto_ch)
 203                 tcf_chain_put_by_act(goto_ch);
 204 release_idr:
 205         tcf_idr_release(*a, bind);
 206         return err;
 207 }
 208
 209 static bool is_mirred_nested(void)
 210 {
 211         return unlikely(__this_cpu_read(mirred_nest_level) > 1);
 212 }
 213
 214 static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
 215 {
 216         int err;
 217
 218         if (!want_ingress)
 219                 err = tcf_dev_queue_xmit(skb, dev_queue_xmit);
 220         else if (is_mirred_nested())
 221                 err = netif_rx(skb);
 222         else
 223                 err = netif_receive_skb(skb);
 224
 225         return err;
 226 }
 227
 228 TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
 229                                      const struct tc_action *a,
 230                                      struct tcf_result *res)
 231 {
 232         struct tcf_mirred *m = to_mirred(a);
 233         struct sk_buff *skb2 = skb;
 234         bool m_mac_header_xmit;
 235         struct net_device *dev;
 236         unsigned int nest_level;
 237         int retval, err = 0;
 238         bool use_reinsert;
 239         bool want_ingress;
 240         bool is_redirect;
 241         bool expects_nh;
 242         bool at_ingress;
 243         int m_eaction;
 244         int mac_len;
 245         bool at_nh;
 246
 247         nest_level = __this_cpu_inc_return(mirred_nest_level);
 248         if (unlikely(nest_level > MIRRED_NEST_LIMIT)) {
 249                 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
 250                                      netdev_name(skb->dev));
 251                 __this_cpu_dec(mirred_nest_level);
 252                 return TC_ACT_SHOT;
 253         }
 254
 255         tcf_lastuse_update(&m->tcf_tm);
 256         tcf_action_update_bstats(&m->common, skb);
 257
 258         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 259         m_eaction = READ_ONCE(m->tcfm_eaction);
 260         retval = READ_ONCE(m->tcf_action);
 261         dev = rcu_dereference_bh(m->tcfm_dev);
 262         if (unlikely(!dev)) {
 263                 pr_notice_once("tc mirred: target device is gone\n");
 264                 goto out;
 265         }
 266
 267         if (unlikely(!(dev->flags & IFF_UP)) || !netif_carrier_ok(dev)) {
 268                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 269                                        dev->name);
 270                 goto out;
 271         }
 272
 273         /* we could easily avoid the clone only if called by ingress and clsact;
 274          * since we can't easily detect the clsact caller, skip clone only for
 275          * ingress - that covers the TC S/W datapath.
 276          */
 277         is_redirect = tcf_mirred_is_act_redirect(m_eaction);
 278         at_ingress = skb_at_tc_ingress(skb);
 279         use_reinsert = at_ingress && is_redirect &&
 280                        tcf_mirred_can_reinsert(retval);
 281         if (!use_reinsert) {
 282                 skb2 = skb_clone(skb, GFP_ATOMIC);
 283                 if (!skb2)
 284                         goto out;
 285         }
 286
 287         want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
 288
 289         /* All mirred/redirected skbs should clear previous ct info */
 290         nf_reset_ct(skb2);
 291         if (want_ingress && !at_ingress) /* drop dst for egress -> ingress */
 292                 skb_dst_drop(skb2);
 293
 294         expects_nh = want_ingress || !m_mac_header_xmit;
 295         at_nh = skb->data == skb_network_header(skb);
 296         if (at_nh != expects_nh) {
 297                 mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
 298                           skb_network_offset(skb);
 299                 if (expects_nh) {
 300                         /* target device/action expect data at nh */
 301                         skb_pull_rcsum(skb2, mac_len);
 302                 } else {
 303                         /* target device/action expect data at mac */
 304                         skb_push_rcsum(skb2, mac_len);
 305                 }
 306         }
 307
 308         skb2->skb_iif = skb->dev->ifindex;
 309         skb2->dev = dev;
 310
 311         /* mirror is always swallowed */
 312         if (is_redirect) {
 313                 skb_set_redirected(skb2, skb2->tc_at_ingress);
 314
 315                 /* let's the caller reinsert the packet, if possible */
 316                 if (use_reinsert) {
 317                         err = tcf_mirred_forward(want_ingress, skb);
 318                         if (err)
 319                                 tcf_action_inc_overlimit_qstats(&m->common);
 320                         __this_cpu_dec(mirred_nest_level);
 321                         return TC_ACT_CONSUMED;
 322                 }
 323         }
 324
 325         err = tcf_mirred_forward(want_ingress, skb2);
 326         if (err) {
 327 out:
 328                 tcf_action_inc_overlimit_qstats(&m->common);
 329                 if (tcf_mirred_is_act_redirect(m_eaction))
 330                         retval = TC_ACT_SHOT;
 331         }
 332         __this_cpu_dec(mirred_nest_level);
 333
 334         return retval;
 335 }
 336
 337 static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
 338                              u64 drops, u64 lastuse, bool hw)
 339 {
 340         struct tcf_mirred *m = to_mirred(a);
 341         struct tcf_t *tm = &m->tcf_tm;
 342
 343         tcf_action_update_stats(a, bytes, packets, drops, hw);
 344         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 345 }
 346
 347 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 348                            int ref)
 349 {
 350         unsigned char *b = skb_tail_pointer(skb);
 351         struct tcf_mirred *m = to_mirred(a);
 352         struct tc_mirred opt = {
 353                 .index   = m->tcf_index,
 354                 .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 355                 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 356         };
 357         struct net_device *dev;
 358         struct tcf_t t;
 359
 360         spin_lock_bh(&m->tcf_lock);
 361         opt.action = m->tcf_action;
 362         opt.eaction = m->tcfm_eaction;
 363         dev = tcf_mirred_dev_dereference(m);
 364         if (dev)
 365                 opt.ifindex = dev->ifindex;
 366
 367         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 368                 goto nla_put_failure;
 369
 370         tcf_tm_dump(&t, &m->tcf_tm);
 371         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 372                 goto nla_put_failure;
 373         spin_unlock_bh(&m->tcf_lock);
 374
 375         return skb->len;
 376
 377 nla_put_failure:
 378         spin_unlock_bh(&m->tcf_lock);
 379         nlmsg_trim(skb, b);
 380         return -1;
 381 }
 382
 383 static int mirred_device_event(struct notifier_block *unused,
 384                                unsigned long event, void *ptr)
 385 {
 386         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 387         struct tcf_mirred *m;
 388
 389         ASSERT_RTNL();
 390         if (event == NETDEV_UNREGISTER) {
 391                 spin_lock(&mirred_list_lock);
 392                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 393                         spin_lock_bh(&m->tcf_lock);
 394                         if (tcf_mirred_dev_dereference(m) == dev) {
 395                                 netdev_put(dev, &m->tcfm_dev_tracker);
 396                                 /* Note : no rcu grace period necessary, as
 397                                  * net_device are already rcu protected.
 398                                  */
 399                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 400                         }
 401                         spin_unlock_bh(&m->tcf_lock);
 402                 }
 403                 spin_unlock(&mirred_list_lock);
 404         }
 405
 406         return NOTIFY_DONE;
 407 }
 408
 409 static struct notifier_block mirred_device_notifier = {
 410         .notifier_call = mirred_device_event,
 411 };
 412
 413 static void tcf_mirred_dev_put(void *priv)
 414 {
 415         struct net_device *dev = priv;
 416
 417         dev_put(dev);
 418 }
 419
 420 static struct net_device *
 421 tcf_mirred_get_dev(const struct tc_action *a,
 422                    tc_action_priv_destructor *destructor)
 423 {
 424         struct tcf_mirred *m = to_mirred(a);
 425         struct net_device *dev;
 426
 427         rcu_read_lock();
 428         dev = rcu_dereference(m->tcfm_dev);
 429         if (dev) {
 430                 dev_hold(dev);
 431                 *destructor = tcf_mirred_dev_put;
 432         }
 433         rcu_read_unlock();
 434
 435         return dev;
 436 }
 437
 438 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
 439 {
 440         return nla_total_size(sizeof(struct tc_mirred));
 441 }
 442
 443 static void tcf_offload_mirred_get_dev(struct flow_action_entry *entry,
 444                                        const struct tc_action *act)
 445 {
 446         entry->dev = act->ops->get_dev(act, &entry->destructor);
 447         if (!entry->dev)
 448                 return;
 449         entry->destructor_priv = entry->dev;
 450 }
 451
 452 static int tcf_mirred_offload_act_setup(struct tc_action *act, void *entry_data,
 453                                         u32 *index_inc, bool bind,
 454                                         struct netlink_ext_ack *extack)
 455 {
 456         if (bind) {
 457                 struct flow_action_entry *entry = entry_data;
 458
 459                 if (is_tcf_mirred_egress_redirect(act)) {
 460                         entry->id = FLOW_ACTION_REDIRECT;
 461                         tcf_offload_mirred_get_dev(entry, act);
 462                 } else if (is_tcf_mirred_egress_mirror(act)) {
 463                         entry->id = FLOW_ACTION_MIRRED;
 464                         tcf_offload_mirred_get_dev(entry, act);
 465                 } else if (is_tcf_mirred_ingress_redirect(act)) {
 466                         entry->id = FLOW_ACTION_REDIRECT_INGRESS;
 467                         tcf_offload_mirred_get_dev(entry, act);
 468                 } else if (is_tcf_mirred_ingress_mirror(act)) {
 469                         entry->id = FLOW_ACTION_MIRRED_INGRESS;
 470                         tcf_offload_mirred_get_dev(entry, act);
 471                 } else {
 472                         NL_SET_ERR_MSG_MOD(extack, "Unsupported mirred offload");
 473                         return -EOPNOTSUPP;
 474                 }
 475                 *index_inc = 1;
 476         } else {
 477                 struct flow_offload_action *fl_action = entry_data;
 478
 479                 if (is_tcf_mirred_egress_redirect(act))
 480                         fl_action->id = FLOW_ACTION_REDIRECT;
 481                 else if (is_tcf_mirred_egress_mirror(act))
 482                         fl_action->id = FLOW_ACTION_MIRRED;
 483                 else if (is_tcf_mirred_ingress_redirect(act))
 484                         fl_action->id = FLOW_ACTION_REDIRECT_INGRESS;
 485                 else if (is_tcf_mirred_ingress_mirror(act))
 486                         fl_action->id = FLOW_ACTION_MIRRED_INGRESS;
 487                 else
 488                         return -EOPNOTSUPP;
 489         }
 490
 491         return 0;
 492 }
 493
 494 static struct tc_action_ops act_mirred_ops = {
 495         .kind           =       "mirred",
 496         .id             =       TCA_ID_MIRRED,
 497         .owner          =       THIS_MODULE,
 498         .act            =       tcf_mirred_act,
 499         .stats_update   =       tcf_stats_update,
 500         .dump           =       tcf_mirred_dump,
 501         .cleanup        =       tcf_mirred_release,
 502         .init           =       tcf_mirred_init,
 503         .get_fill_size  =       tcf_mirred_get_fill_size,
 504         .offload_act_setup =    tcf_mirred_offload_act_setup,
 505         .size           =       sizeof(struct tcf_mirred),
 506         .get_dev        =       tcf_mirred_get_dev,
 507 };
 508
 509 static __net_init int mirred_init_net(struct net *net)
 510 {
 511         struct tc_action_net *tn = net_generic(net, act_mirred_ops.net_id);
 512
 513         return tc_action_net_init(net, tn, &act_mirred_ops);
 514 }
 515
 516 static void __net_exit mirred_exit_net(struct list_head *net_list)
 517 {
 518         tc_action_net_exit(net_list, act_mirred_ops.net_id);
 519 }
 520
 521 static struct pernet_operations mirred_net_ops = {
 522         .init = mirred_init_net,
 523         .exit_batch = mirred_exit_net,
 524         .id   = &act_mirred_ops.net_id,
 525         .size = sizeof(struct tc_action_net),
 526 };
 527
 528 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 529 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 530 MODULE_LICENSE("GPL");
 531
 532 static int __init mirred_init_module(void)
 533 {
 534         int err = register_netdevice_notifier(&mirred_device_notifier);
 535         if (err)
 536                 return err;
 537
 538         pr_info("Mirror/redirect action on\n");
 539         err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 540         if (err)
 541                 unregister_netdevice_notifier(&mirred_device_notifier);
 542
 543         return err;
 544 }
 545
 546 static void __exit mirred_cleanup_module(void)
 547 {
 548         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 549         unregister_netdevice_notifier(&mirred_device_notifier);
 550 }
 551
 552 module_init(mirred_init_module);
 553 module_exit(mirred_cleanup_module);