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 dev_put(dev); 82 } 83 84 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 85 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 86 }; 87 88 static unsigned int mirred_net_id; 89 static struct tc_action_ops act_mirred_ops; 90 91 static int tcf_mirred_init(struct net *net, struct nlattr *nla, 92 struct nlattr *est, struct tc_action **a, 93 struct tcf_proto *tp, 94 u32 flags, struct netlink_ext_ack *extack) 95 { 96 struct tc_action_net *tn = net_generic(net, mirred_net_id); 97 bool bind = flags & TCA_ACT_FLAGS_BIND; 98 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 99 struct tcf_chain *goto_ch = NULL; 100 bool mac_header_xmit = false; 101 struct tc_mirred *parm; 102 struct tcf_mirred *m; 103 struct net_device *dev; 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 dev = dev_get_by_index(net, parm->ifindex); 174 if (!dev) { 175 spin_unlock_bh(&m->tcf_lock); 176 err = -ENODEV; 177 goto put_chain; 178 } 179 mac_header_xmit = dev_is_mac_header_xmit(dev); 180 dev = rcu_replace_pointer(m->tcfm_dev, dev, 181 lockdep_is_held(&m->tcf_lock)); 182 dev_put(dev); 183 m->tcfm_mac_header_xmit = mac_header_xmit; 184 } 185 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 186 m->tcfm_eaction = parm->eaction; 187 spin_unlock_bh(&m->tcf_lock); 188 if (goto_ch) 189 tcf_chain_put_by_act(goto_ch); 190 191 if (ret == ACT_P_CREATED) { 192 spin_lock(&mirred_list_lock); 193 list_add(&m->tcfm_list, &mirred_list); 194 spin_unlock(&mirred_list_lock); 195 } 196 197 return ret; 198 put_chain: 199 if (goto_ch) 200 tcf_chain_put_by_act(goto_ch); 201 release_idr: 202 tcf_idr_release(*a, bind); 203 return err; 204 } 205 206 static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb) 207 { 208 int err; 209 210 if (!want_ingress) 211 err = tcf_dev_queue_xmit(skb, dev_queue_xmit); 212 else 213 err = netif_receive_skb(skb); 214 215 return err; 216 } 217 218 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a, 219 struct tcf_result *res) 220 { 221 struct tcf_mirred *m = to_mirred(a); 222 struct sk_buff *skb2 = skb; 223 bool m_mac_header_xmit; 224 struct net_device *dev; 225 unsigned int rec_level; 226 int retval, err = 0; 227 bool use_reinsert; 228 bool want_ingress; 229 bool is_redirect; 230 bool expects_nh; 231 int m_eaction; 232 int mac_len; 233 bool at_nh; 234 235 rec_level = __this_cpu_inc_return(mirred_rec_level); 236 if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) { 237 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n", 238 netdev_name(skb->dev)); 239 __this_cpu_dec(mirred_rec_level); 240 return TC_ACT_SHOT; 241 } 242 243 tcf_lastuse_update(&m->tcf_tm); 244 tcf_action_update_bstats(&m->common, skb); 245 246 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 247 m_eaction = READ_ONCE(m->tcfm_eaction); 248 retval = READ_ONCE(m->tcf_action); 249 dev = rcu_dereference_bh(m->tcfm_dev); 250 if (unlikely(!dev)) { 251 pr_notice_once("tc mirred: target device is gone\n"); 252 goto out; 253 } 254 255 if (unlikely(!(dev->flags & IFF_UP))) { 256 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 257 dev->name); 258 goto out; 259 } 260 261 /* we could easily avoid the clone only if called by ingress and clsact; 262 * since we can't easily detect the clsact caller, skip clone only for 263 * ingress - that covers the TC S/W datapath. 264 */ 265 is_redirect = tcf_mirred_is_act_redirect(m_eaction); 266 use_reinsert = skb_at_tc_ingress(skb) && is_redirect && 267 tcf_mirred_can_reinsert(retval); 268 if (!use_reinsert) { 269 skb2 = skb_clone(skb, GFP_ATOMIC); 270 if (!skb2) 271 goto out; 272 } 273 274 /* All mirred/redirected skbs should clear previous ct info */ 275 nf_reset_ct(skb2); 276 277 want_ingress = tcf_mirred_act_wants_ingress(m_eaction); 278 279 expects_nh = want_ingress || !m_mac_header_xmit; 280 at_nh = skb->data == skb_network_header(skb); 281 if (at_nh != expects_nh) { 282 mac_len = skb_at_tc_ingress(skb) ? skb->mac_len : 283 skb_network_header(skb) - skb_mac_header(skb); 284 if (expects_nh) { 285 /* target device/action expect data at nh */ 286 skb_pull_rcsum(skb2, mac_len); 287 } else { 288 /* target device/action expect data at mac */ 289 skb_push_rcsum(skb2, mac_len); 290 } 291 } 292 293 skb2->skb_iif = skb->dev->ifindex; 294 skb2->dev = dev; 295 296 /* mirror is always swallowed */ 297 if (is_redirect) { 298 skb_set_redirected(skb2, skb2->tc_at_ingress); 299 300 /* let's the caller reinsert the packet, if possible */ 301 if (use_reinsert) { 302 res->ingress = want_ingress; 303 err = tcf_mirred_forward(res->ingress, skb); 304 if (err) 305 tcf_action_inc_overlimit_qstats(&m->common); 306 __this_cpu_dec(mirred_rec_level); 307 return TC_ACT_CONSUMED; 308 } 309 } 310 311 err = tcf_mirred_forward(want_ingress, skb2); 312 if (err) { 313 out: 314 tcf_action_inc_overlimit_qstats(&m->common); 315 if (tcf_mirred_is_act_redirect(m_eaction)) 316 retval = TC_ACT_SHOT; 317 } 318 __this_cpu_dec(mirred_rec_level); 319 320 return retval; 321 } 322 323 static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets, 324 u64 drops, u64 lastuse, bool hw) 325 { 326 struct tcf_mirred *m = to_mirred(a); 327 struct tcf_t *tm = &m->tcf_tm; 328 329 tcf_action_update_stats(a, bytes, packets, drops, hw); 330 tm->lastuse = max_t(u64, tm->lastuse, lastuse); 331 } 332 333 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 334 int ref) 335 { 336 unsigned char *b = skb_tail_pointer(skb); 337 struct tcf_mirred *m = to_mirred(a); 338 struct tc_mirred opt = { 339 .index = m->tcf_index, 340 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 341 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 342 }; 343 struct net_device *dev; 344 struct tcf_t t; 345 346 spin_lock_bh(&m->tcf_lock); 347 opt.action = m->tcf_action; 348 opt.eaction = m->tcfm_eaction; 349 dev = tcf_mirred_dev_dereference(m); 350 if (dev) 351 opt.ifindex = dev->ifindex; 352 353 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 354 goto nla_put_failure; 355 356 tcf_tm_dump(&t, &m->tcf_tm); 357 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 358 goto nla_put_failure; 359 spin_unlock_bh(&m->tcf_lock); 360 361 return skb->len; 362 363 nla_put_failure: 364 spin_unlock_bh(&m->tcf_lock); 365 nlmsg_trim(skb, b); 366 return -1; 367 } 368 369 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 370 struct netlink_callback *cb, int type, 371 const struct tc_action_ops *ops, 372 struct netlink_ext_ack *extack) 373 { 374 struct tc_action_net *tn = net_generic(net, mirred_net_id); 375 376 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 377 } 378 379 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 380 { 381 struct tc_action_net *tn = net_generic(net, mirred_net_id); 382 383 return tcf_idr_search(tn, a, index); 384 } 385 386 static int mirred_device_event(struct notifier_block *unused, 387 unsigned long event, void *ptr) 388 { 389 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 390 struct tcf_mirred *m; 391 392 ASSERT_RTNL(); 393 if (event == NETDEV_UNREGISTER) { 394 spin_lock(&mirred_list_lock); 395 list_for_each_entry(m, &mirred_list, tcfm_list) { 396 spin_lock_bh(&m->tcf_lock); 397 if (tcf_mirred_dev_dereference(m) == dev) { 398 dev_put(dev); 399 /* Note : no rcu grace period necessary, as 400 * net_device are already rcu protected. 401 */ 402 RCU_INIT_POINTER(m->tcfm_dev, NULL); 403 } 404 spin_unlock_bh(&m->tcf_lock); 405 } 406 spin_unlock(&mirred_list_lock); 407 } 408 409 return NOTIFY_DONE; 410 } 411 412 static struct notifier_block mirred_device_notifier = { 413 .notifier_call = mirred_device_event, 414 }; 415 416 static void tcf_mirred_dev_put(void *priv) 417 { 418 struct net_device *dev = priv; 419 420 dev_put(dev); 421 } 422 423 static struct net_device * 424 tcf_mirred_get_dev(const struct tc_action *a, 425 tc_action_priv_destructor *destructor) 426 { 427 struct tcf_mirred *m = to_mirred(a); 428 struct net_device *dev; 429 430 rcu_read_lock(); 431 dev = rcu_dereference(m->tcfm_dev); 432 if (dev) { 433 dev_hold(dev); 434 *destructor = tcf_mirred_dev_put; 435 } 436 rcu_read_unlock(); 437 438 return dev; 439 } 440 441 static size_t tcf_mirred_get_fill_size(const struct tc_action *act) 442 { 443 return nla_total_size(sizeof(struct tc_mirred)); 444 } 445 446 static struct tc_action_ops act_mirred_ops = { 447 .kind = "mirred", 448 .id = TCA_ID_MIRRED, 449 .owner = THIS_MODULE, 450 .act = tcf_mirred_act, 451 .stats_update = tcf_stats_update, 452 .dump = tcf_mirred_dump, 453 .cleanup = tcf_mirred_release, 454 .init = tcf_mirred_init, 455 .walk = tcf_mirred_walker, 456 .lookup = tcf_mirred_search, 457 .get_fill_size = tcf_mirred_get_fill_size, 458 .size = sizeof(struct tcf_mirred), 459 .get_dev = tcf_mirred_get_dev, 460 }; 461 462 static __net_init int mirred_init_net(struct net *net) 463 { 464 struct tc_action_net *tn = net_generic(net, mirred_net_id); 465 466 return tc_action_net_init(net, tn, &act_mirred_ops); 467 } 468 469 static void __net_exit mirred_exit_net(struct list_head *net_list) 470 { 471 tc_action_net_exit(net_list, mirred_net_id); 472 } 473 474 static struct pernet_operations mirred_net_ops = { 475 .init = mirred_init_net, 476 .exit_batch = mirred_exit_net, 477 .id = &mirred_net_id, 478 .size = sizeof(struct tc_action_net), 479 }; 480 481 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 482 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 483 MODULE_LICENSE("GPL"); 484 485 static int __init mirred_init_module(void) 486 { 487 int err = register_netdevice_notifier(&mirred_device_notifier); 488 if (err) 489 return err; 490 491 pr_info("Mirror/redirect action on\n"); 492 err = tcf_register_action(&act_mirred_ops, &mirred_net_ops); 493 if (err) 494 unregister_netdevice_notifier(&mirred_device_notifier); 495 496 return err; 497 } 498 499 static void __exit mirred_cleanup_module(void) 500 { 501 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 502 unregister_netdevice_notifier(&mirred_device_notifier); 503 } 504 505 module_init(mirred_init_module); 506 module_exit(mirred_cleanup_module); 507