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/pkt_sched.h> 23 #include <net/pkt_cls.h> 24 #include <linux/tc_act/tc_mirred.h> 25 #include <net/tc_act/tc_mirred.h> 26 27 static LIST_HEAD(mirred_list); 28 static DEFINE_SPINLOCK(mirred_list_lock); 29 30 #define MIRRED_RECURSION_LIMIT 4 31 static DEFINE_PER_CPU(unsigned int, mirred_rec_level); 32 33 static bool tcf_mirred_is_act_redirect(int action) 34 { 35 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR; 36 } 37 38 static bool tcf_mirred_act_wants_ingress(int action) 39 { 40 switch (action) { 41 case TCA_EGRESS_REDIR: 42 case TCA_EGRESS_MIRROR: 43 return false; 44 case TCA_INGRESS_REDIR: 45 case TCA_INGRESS_MIRROR: 46 return true; 47 default: 48 BUG(); 49 } 50 } 51 52 static bool tcf_mirred_can_reinsert(int action) 53 { 54 switch (action) { 55 case TC_ACT_SHOT: 56 case TC_ACT_STOLEN: 57 case TC_ACT_QUEUED: 58 case TC_ACT_TRAP: 59 return true; 60 } 61 return false; 62 } 63 64 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m) 65 { 66 return rcu_dereference_protected(m->tcfm_dev, 67 lockdep_is_held(&m->tcf_lock)); 68 } 69 70 static void tcf_mirred_release(struct tc_action *a) 71 { 72 struct tcf_mirred *m = to_mirred(a); 73 struct net_device *dev; 74 75 spin_lock(&mirred_list_lock); 76 list_del(&m->tcfm_list); 77 spin_unlock(&mirred_list_lock); 78 79 /* last reference to action, no need to lock */ 80 dev = rcu_dereference_protected(m->tcfm_dev, 1); 81 if (dev) 82 dev_put(dev); 83 } 84 85 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 86 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 87 }; 88 89 static unsigned int mirred_net_id; 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 int ovr, int bind, bool rtnl_held, 95 struct tcf_proto *tp, 96 struct netlink_ext_ack *extack) 97 { 98 struct tc_action_net *tn = net_generic(net, mirred_net_id); 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 struct net_device *dev; 105 bool exists = false; 106 int ret, err; 107 u32 index; 108 109 if (!nla) { 110 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed"); 111 return -EINVAL; 112 } 113 ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla, 114 mirred_policy, extack); 115 if (ret < 0) 116 return ret; 117 if (!tb[TCA_MIRRED_PARMS]) { 118 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters"); 119 return -EINVAL; 120 } 121 parm = nla_data(tb[TCA_MIRRED_PARMS]); 122 index = parm->index; 123 err = tcf_idr_check_alloc(tn, &index, a, bind); 124 if (err < 0) 125 return err; 126 exists = err; 127 if (exists && bind) 128 return 0; 129 130 switch (parm->eaction) { 131 case TCA_EGRESS_MIRROR: 132 case TCA_EGRESS_REDIR: 133 case TCA_INGRESS_REDIR: 134 case TCA_INGRESS_MIRROR: 135 break; 136 default: 137 if (exists) 138 tcf_idr_release(*a, bind); 139 else 140 tcf_idr_cleanup(tn, index); 141 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 142 return -EINVAL; 143 } 144 145 if (!exists) { 146 if (!parm->ifindex) { 147 tcf_idr_cleanup(tn, index); 148 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 149 return -EINVAL; 150 } 151 ret = tcf_idr_create(tn, index, est, a, 152 &act_mirred_ops, bind, true); 153 if (ret) { 154 tcf_idr_cleanup(tn, index); 155 return ret; 156 } 157 ret = ACT_P_CREATED; 158 } else if (!ovr) { 159 tcf_idr_release(*a, bind); 160 return -EEXIST; 161 } 162 163 m = to_mirred(*a); 164 if (ret == ACT_P_CREATED) 165 INIT_LIST_HEAD(&m->tcfm_list); 166 167 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 168 if (err < 0) 169 goto release_idr; 170 171 spin_lock_bh(&m->tcf_lock); 172 173 if (parm->ifindex) { 174 dev = dev_get_by_index(net, parm->ifindex); 175 if (!dev) { 176 spin_unlock_bh(&m->tcf_lock); 177 err = -ENODEV; 178 goto put_chain; 179 } 180 mac_header_xmit = dev_is_mac_header_xmit(dev); 181 rcu_swap_protected(m->tcfm_dev, dev, 182 lockdep_is_held(&m->tcf_lock)); 183 if (dev) 184 dev_put(dev); 185 m->tcfm_mac_header_xmit = mac_header_xmit; 186 } 187 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 188 m->tcfm_eaction = parm->eaction; 189 spin_unlock_bh(&m->tcf_lock); 190 if (goto_ch) 191 tcf_chain_put_by_act(goto_ch); 192 193 if (ret == ACT_P_CREATED) { 194 spin_lock(&mirred_list_lock); 195 list_add(&m->tcfm_list, &mirred_list); 196 spin_unlock(&mirred_list_lock); 197 198 tcf_idr_insert(tn, *a); 199 } 200 201 return ret; 202 put_chain: 203 if (goto_ch) 204 tcf_chain_put_by_act(goto_ch); 205 release_idr: 206 tcf_idr_release(*a, bind); 207 return err; 208 } 209 210 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a, 211 struct tcf_result *res) 212 { 213 struct tcf_mirred *m = to_mirred(a); 214 struct sk_buff *skb2 = skb; 215 bool m_mac_header_xmit; 216 struct net_device *dev; 217 unsigned int rec_level; 218 int retval, err = 0; 219 bool use_reinsert; 220 bool want_ingress; 221 bool is_redirect; 222 int m_eaction; 223 int mac_len; 224 225 rec_level = __this_cpu_inc_return(mirred_rec_level); 226 if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) { 227 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n", 228 netdev_name(skb->dev)); 229 __this_cpu_dec(mirred_rec_level); 230 return TC_ACT_SHOT; 231 } 232 233 tcf_lastuse_update(&m->tcf_tm); 234 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 235 236 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 237 m_eaction = READ_ONCE(m->tcfm_eaction); 238 retval = READ_ONCE(m->tcf_action); 239 dev = rcu_dereference_bh(m->tcfm_dev); 240 if (unlikely(!dev)) { 241 pr_notice_once("tc mirred: target device is gone\n"); 242 goto out; 243 } 244 245 if (unlikely(!(dev->flags & IFF_UP))) { 246 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 247 dev->name); 248 goto out; 249 } 250 251 /* we could easily avoid the clone only if called by ingress and clsact; 252 * since we can't easily detect the clsact caller, skip clone only for 253 * ingress - that covers the TC S/W datapath. 254 */ 255 is_redirect = tcf_mirred_is_act_redirect(m_eaction); 256 use_reinsert = skb_at_tc_ingress(skb) && is_redirect && 257 tcf_mirred_can_reinsert(retval); 258 if (!use_reinsert) { 259 skb2 = skb_clone(skb, GFP_ATOMIC); 260 if (!skb2) 261 goto out; 262 } 263 264 /* If action's target direction differs than filter's direction, 265 * and devices expect a mac header on xmit, then mac push/pull is 266 * needed. 267 */ 268 want_ingress = tcf_mirred_act_wants_ingress(m_eaction); 269 if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) { 270 if (!skb_at_tc_ingress(skb)) { 271 /* caught at egress, act ingress: pull mac */ 272 mac_len = skb_network_header(skb) - skb_mac_header(skb); 273 skb_pull_rcsum(skb2, mac_len); 274 } else { 275 /* caught at ingress, act egress: push mac */ 276 skb_push_rcsum(skb2, skb->mac_len); 277 } 278 } 279 280 skb2->skb_iif = skb->dev->ifindex; 281 skb2->dev = dev; 282 283 /* mirror is always swallowed */ 284 if (is_redirect) { 285 skb2->tc_redirected = 1; 286 skb2->tc_from_ingress = skb2->tc_at_ingress; 287 if (skb2->tc_from_ingress) 288 skb2->tstamp = 0; 289 /* let's the caller reinsert the packet, if possible */ 290 if (use_reinsert) { 291 res->ingress = want_ingress; 292 res->qstats = this_cpu_ptr(m->common.cpu_qstats); 293 skb_tc_reinsert(skb, res); 294 __this_cpu_dec(mirred_rec_level); 295 return TC_ACT_CONSUMED; 296 } 297 } 298 299 if (!want_ingress) 300 err = dev_queue_xmit(skb2); 301 else 302 err = netif_receive_skb(skb2); 303 304 if (err) { 305 out: 306 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); 307 if (tcf_mirred_is_act_redirect(m_eaction)) 308 retval = TC_ACT_SHOT; 309 } 310 __this_cpu_dec(mirred_rec_level); 311 312 return retval; 313 } 314 315 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets, 316 u64 lastuse, bool hw) 317 { 318 struct tcf_mirred *m = to_mirred(a); 319 struct tcf_t *tm = &m->tcf_tm; 320 321 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets); 322 if (hw) 323 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw), 324 bytes, packets); 325 tm->lastuse = max_t(u64, tm->lastuse, lastuse); 326 } 327 328 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 329 int ref) 330 { 331 unsigned char *b = skb_tail_pointer(skb); 332 struct tcf_mirred *m = to_mirred(a); 333 struct tc_mirred opt = { 334 .index = m->tcf_index, 335 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 336 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 337 }; 338 struct net_device *dev; 339 struct tcf_t t; 340 341 spin_lock_bh(&m->tcf_lock); 342 opt.action = m->tcf_action; 343 opt.eaction = m->tcfm_eaction; 344 dev = tcf_mirred_dev_dereference(m); 345 if (dev) 346 opt.ifindex = dev->ifindex; 347 348 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 349 goto nla_put_failure; 350 351 tcf_tm_dump(&t, &m->tcf_tm); 352 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 353 goto nla_put_failure; 354 spin_unlock_bh(&m->tcf_lock); 355 356 return skb->len; 357 358 nla_put_failure: 359 spin_unlock_bh(&m->tcf_lock); 360 nlmsg_trim(skb, b); 361 return -1; 362 } 363 364 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 365 struct netlink_callback *cb, int type, 366 const struct tc_action_ops *ops, 367 struct netlink_ext_ack *extack) 368 { 369 struct tc_action_net *tn = net_generic(net, mirred_net_id); 370 371 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 372 } 373 374 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 375 { 376 struct tc_action_net *tn = net_generic(net, mirred_net_id); 377 378 return tcf_idr_search(tn, a, index); 379 } 380 381 static int mirred_device_event(struct notifier_block *unused, 382 unsigned long event, void *ptr) 383 { 384 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 385 struct tcf_mirred *m; 386 387 ASSERT_RTNL(); 388 if (event == NETDEV_UNREGISTER) { 389 spin_lock(&mirred_list_lock); 390 list_for_each_entry(m, &mirred_list, tcfm_list) { 391 spin_lock_bh(&m->tcf_lock); 392 if (tcf_mirred_dev_dereference(m) == dev) { 393 dev_put(dev); 394 /* Note : no rcu grace period necessary, as 395 * net_device are already rcu protected. 396 */ 397 RCU_INIT_POINTER(m->tcfm_dev, NULL); 398 } 399 spin_unlock_bh(&m->tcf_lock); 400 } 401 spin_unlock(&mirred_list_lock); 402 } 403 404 return NOTIFY_DONE; 405 } 406 407 static struct notifier_block mirred_device_notifier = { 408 .notifier_call = mirred_device_event, 409 }; 410 411 static void tcf_mirred_dev_put(void *priv) 412 { 413 struct net_device *dev = priv; 414 415 dev_put(dev); 416 } 417 418 static struct net_device * 419 tcf_mirred_get_dev(const struct tc_action *a, 420 tc_action_priv_destructor *destructor) 421 { 422 struct tcf_mirred *m = to_mirred(a); 423 struct net_device *dev; 424 425 rcu_read_lock(); 426 dev = rcu_dereference(m->tcfm_dev); 427 if (dev) { 428 dev_hold(dev); 429 *destructor = tcf_mirred_dev_put; 430 } 431 rcu_read_unlock(); 432 433 return dev; 434 } 435 436 static size_t tcf_mirred_get_fill_size(const struct tc_action *act) 437 { 438 return nla_total_size(sizeof(struct tc_mirred)); 439 } 440 441 static struct tc_action_ops act_mirred_ops = { 442 .kind = "mirred", 443 .id = TCA_ID_MIRRED, 444 .owner = THIS_MODULE, 445 .act = tcf_mirred_act, 446 .stats_update = tcf_stats_update, 447 .dump = tcf_mirred_dump, 448 .cleanup = tcf_mirred_release, 449 .init = tcf_mirred_init, 450 .walk = tcf_mirred_walker, 451 .lookup = tcf_mirred_search, 452 .get_fill_size = tcf_mirred_get_fill_size, 453 .size = sizeof(struct tcf_mirred), 454 .get_dev = tcf_mirred_get_dev, 455 }; 456 457 static __net_init int mirred_init_net(struct net *net) 458 { 459 struct tc_action_net *tn = net_generic(net, mirred_net_id); 460 461 return tc_action_net_init(net, tn, &act_mirred_ops); 462 } 463 464 static void __net_exit mirred_exit_net(struct list_head *net_list) 465 { 466 tc_action_net_exit(net_list, mirred_net_id); 467 } 468 469 static struct pernet_operations mirred_net_ops = { 470 .init = mirred_init_net, 471 .exit_batch = mirred_exit_net, 472 .id = &mirred_net_id, 473 .size = sizeof(struct tc_action_net), 474 }; 475 476 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 477 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 478 MODULE_LICENSE("GPL"); 479 480 static int __init mirred_init_module(void) 481 { 482 int err = register_netdevice_notifier(&mirred_device_notifier); 483 if (err) 484 return err; 485 486 pr_info("Mirror/redirect action on\n"); 487 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 488 } 489 490 static void __exit mirred_cleanup_module(void) 491 { 492 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 493 unregister_netdevice_notifier(&mirred_device_notifier); 494 } 495 496 module_init(mirred_init_module); 497 module_exit(mirred_cleanup_module); 498