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); 554