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 static bool tcf_mirred_is_act_redirect(int action) 31 { 32 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR; 33 } 34 35 static bool tcf_mirred_act_wants_ingress(int action) 36 { 37 switch (action) { 38 case TCA_EGRESS_REDIR: 39 case TCA_EGRESS_MIRROR: 40 return false; 41 case TCA_INGRESS_REDIR: 42 case TCA_INGRESS_MIRROR: 43 return true; 44 default: 45 BUG(); 46 } 47 } 48 49 static bool tcf_mirred_can_reinsert(int action) 50 { 51 switch (action) { 52 case TC_ACT_SHOT: 53 case TC_ACT_STOLEN: 54 case TC_ACT_QUEUED: 55 case TC_ACT_TRAP: 56 return true; 57 } 58 return false; 59 } 60 61 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m) 62 { 63 return rcu_dereference_protected(m->tcfm_dev, 64 lockdep_is_held(&m->tcf_lock)); 65 } 66 67 static void tcf_mirred_release(struct tc_action *a) 68 { 69 struct tcf_mirred *m = to_mirred(a); 70 struct net_device *dev; 71 72 spin_lock(&mirred_list_lock); 73 list_del(&m->tcfm_list); 74 spin_unlock(&mirred_list_lock); 75 76 /* last reference to action, no need to lock */ 77 dev = rcu_dereference_protected(m->tcfm_dev, 1); 78 if (dev) 79 dev_put(dev); 80 } 81 82 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 83 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 84 }; 85 86 static unsigned int mirred_net_id; 87 static struct tc_action_ops act_mirred_ops; 88 89 static int tcf_mirred_init(struct net *net, struct nlattr *nla, 90 struct nlattr *est, struct tc_action **a, 91 int ovr, int bind, bool rtnl_held, 92 struct tcf_proto *tp, 93 struct netlink_ext_ack *extack) 94 { 95 struct tc_action_net *tn = net_generic(net, mirred_net_id); 96 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 97 struct tcf_chain *goto_ch = NULL; 98 bool mac_header_xmit = false; 99 struct tc_mirred *parm; 100 struct tcf_mirred *m; 101 struct net_device *dev; 102 bool exists = false; 103 int ret, err; 104 105 if (!nla) { 106 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed"); 107 return -EINVAL; 108 } 109 ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla, 110 mirred_policy, extack); 111 if (ret < 0) 112 return ret; 113 if (!tb[TCA_MIRRED_PARMS]) { 114 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters"); 115 return -EINVAL; 116 } 117 parm = nla_data(tb[TCA_MIRRED_PARMS]); 118 119 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 120 if (err < 0) 121 return err; 122 exists = err; 123 if (exists && bind) 124 return 0; 125 126 switch (parm->eaction) { 127 case TCA_EGRESS_MIRROR: 128 case TCA_EGRESS_REDIR: 129 case TCA_INGRESS_REDIR: 130 case TCA_INGRESS_MIRROR: 131 break; 132 default: 133 if (exists) 134 tcf_idr_release(*a, bind); 135 else 136 tcf_idr_cleanup(tn, parm->index); 137 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 138 return -EINVAL; 139 } 140 141 if (!exists) { 142 if (!parm->ifindex) { 143 tcf_idr_cleanup(tn, parm->index); 144 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 145 return -EINVAL; 146 } 147 ret = tcf_idr_create(tn, parm->index, est, a, 148 &act_mirred_ops, bind, true); 149 if (ret) { 150 tcf_idr_cleanup(tn, parm->index); 151 return ret; 152 } 153 ret = ACT_P_CREATED; 154 } else if (!ovr) { 155 tcf_idr_release(*a, bind); 156 return -EEXIST; 157 } 158 159 m = to_mirred(*a); 160 if (ret == ACT_P_CREATED) 161 INIT_LIST_HEAD(&m->tcfm_list); 162 163 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 164 if (err < 0) 165 goto release_idr; 166 167 spin_lock_bh(&m->tcf_lock); 168 169 if (parm->ifindex) { 170 dev = dev_get_by_index(net, parm->ifindex); 171 if (!dev) { 172 spin_unlock_bh(&m->tcf_lock); 173 err = -ENODEV; 174 goto put_chain; 175 } 176 mac_header_xmit = dev_is_mac_header_xmit(dev); 177 rcu_swap_protected(m->tcfm_dev, dev, 178 lockdep_is_held(&m->tcf_lock)); 179 if (dev) 180 dev_put(dev); 181 m->tcfm_mac_header_xmit = mac_header_xmit; 182 } 183 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 184 m->tcfm_eaction = parm->eaction; 185 spin_unlock_bh(&m->tcf_lock); 186 if (goto_ch) 187 tcf_chain_put_by_act(goto_ch); 188 189 if (ret == ACT_P_CREATED) { 190 spin_lock(&mirred_list_lock); 191 list_add(&m->tcfm_list, &mirred_list); 192 spin_unlock(&mirred_list_lock); 193 194 tcf_idr_insert(tn, *a); 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_act(struct sk_buff *skb, const struct tc_action *a, 207 struct tcf_result *res) 208 { 209 struct tcf_mirred *m = to_mirred(a); 210 struct sk_buff *skb2 = skb; 211 bool m_mac_header_xmit; 212 struct net_device *dev; 213 int retval, err = 0; 214 bool use_reinsert; 215 bool want_ingress; 216 bool is_redirect; 217 int m_eaction; 218 int mac_len; 219 220 tcf_lastuse_update(&m->tcf_tm); 221 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 222 223 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 224 m_eaction = READ_ONCE(m->tcfm_eaction); 225 retval = READ_ONCE(m->tcf_action); 226 dev = rcu_dereference_bh(m->tcfm_dev); 227 if (unlikely(!dev)) { 228 pr_notice_once("tc mirred: target device is gone\n"); 229 goto out; 230 } 231 232 if (unlikely(!(dev->flags & IFF_UP))) { 233 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 234 dev->name); 235 goto out; 236 } 237 238 /* we could easily avoid the clone only if called by ingress and clsact; 239 * since we can't easily detect the clsact caller, skip clone only for 240 * ingress - that covers the TC S/W datapath. 241 */ 242 is_redirect = tcf_mirred_is_act_redirect(m_eaction); 243 use_reinsert = skb_at_tc_ingress(skb) && is_redirect && 244 tcf_mirred_can_reinsert(retval); 245 if (!use_reinsert) { 246 skb2 = skb_clone(skb, GFP_ATOMIC); 247 if (!skb2) 248 goto out; 249 } 250 251 /* If action's target direction differs than filter's direction, 252 * and devices expect a mac header on xmit, then mac push/pull is 253 * needed. 254 */ 255 want_ingress = tcf_mirred_act_wants_ingress(m_eaction); 256 if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) { 257 if (!skb_at_tc_ingress(skb)) { 258 /* caught at egress, act ingress: pull mac */ 259 mac_len = skb_network_header(skb) - skb_mac_header(skb); 260 skb_pull_rcsum(skb2, mac_len); 261 } else { 262 /* caught at ingress, act egress: push mac */ 263 skb_push_rcsum(skb2, skb->mac_len); 264 } 265 } 266 267 skb2->skb_iif = skb->dev->ifindex; 268 skb2->dev = dev; 269 270 /* mirror is always swallowed */ 271 if (is_redirect) { 272 skb2->tc_redirected = 1; 273 skb2->tc_from_ingress = skb2->tc_at_ingress; 274 if (skb2->tc_from_ingress) 275 skb2->tstamp = 0; 276 /* let's the caller reinsert the packet, if possible */ 277 if (use_reinsert) { 278 res->ingress = want_ingress; 279 res->qstats = this_cpu_ptr(m->common.cpu_qstats); 280 return TC_ACT_REINSERT; 281 } 282 } 283 284 if (!want_ingress) 285 err = dev_queue_xmit(skb2); 286 else 287 err = netif_receive_skb(skb2); 288 289 if (err) { 290 out: 291 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); 292 if (tcf_mirred_is_act_redirect(m_eaction)) 293 retval = TC_ACT_SHOT; 294 } 295 296 return retval; 297 } 298 299 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets, 300 u64 lastuse, bool hw) 301 { 302 struct tcf_mirred *m = to_mirred(a); 303 struct tcf_t *tm = &m->tcf_tm; 304 305 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets); 306 if (hw) 307 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw), 308 bytes, packets); 309 tm->lastuse = max_t(u64, tm->lastuse, lastuse); 310 } 311 312 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 313 int ref) 314 { 315 unsigned char *b = skb_tail_pointer(skb); 316 struct tcf_mirred *m = to_mirred(a); 317 struct tc_mirred opt = { 318 .index = m->tcf_index, 319 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 320 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 321 }; 322 struct net_device *dev; 323 struct tcf_t t; 324 325 spin_lock_bh(&m->tcf_lock); 326 opt.action = m->tcf_action; 327 opt.eaction = m->tcfm_eaction; 328 dev = tcf_mirred_dev_dereference(m); 329 if (dev) 330 opt.ifindex = dev->ifindex; 331 332 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 333 goto nla_put_failure; 334 335 tcf_tm_dump(&t, &m->tcf_tm); 336 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 337 goto nla_put_failure; 338 spin_unlock_bh(&m->tcf_lock); 339 340 return skb->len; 341 342 nla_put_failure: 343 spin_unlock_bh(&m->tcf_lock); 344 nlmsg_trim(skb, b); 345 return -1; 346 } 347 348 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 349 struct netlink_callback *cb, int type, 350 const struct tc_action_ops *ops, 351 struct netlink_ext_ack *extack) 352 { 353 struct tc_action_net *tn = net_generic(net, mirred_net_id); 354 355 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 356 } 357 358 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 359 { 360 struct tc_action_net *tn = net_generic(net, mirred_net_id); 361 362 return tcf_idr_search(tn, a, index); 363 } 364 365 static int mirred_device_event(struct notifier_block *unused, 366 unsigned long event, void *ptr) 367 { 368 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 369 struct tcf_mirred *m; 370 371 ASSERT_RTNL(); 372 if (event == NETDEV_UNREGISTER) { 373 spin_lock(&mirred_list_lock); 374 list_for_each_entry(m, &mirred_list, tcfm_list) { 375 spin_lock_bh(&m->tcf_lock); 376 if (tcf_mirred_dev_dereference(m) == dev) { 377 dev_put(dev); 378 /* Note : no rcu grace period necessary, as 379 * net_device are already rcu protected. 380 */ 381 RCU_INIT_POINTER(m->tcfm_dev, NULL); 382 } 383 spin_unlock_bh(&m->tcf_lock); 384 } 385 spin_unlock(&mirred_list_lock); 386 } 387 388 return NOTIFY_DONE; 389 } 390 391 static struct notifier_block mirred_device_notifier = { 392 .notifier_call = mirred_device_event, 393 }; 394 395 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a) 396 { 397 struct tcf_mirred *m = to_mirred(a); 398 struct net_device *dev; 399 400 rcu_read_lock(); 401 dev = rcu_dereference(m->tcfm_dev); 402 if (dev) 403 dev_hold(dev); 404 rcu_read_unlock(); 405 406 return dev; 407 } 408 409 static void tcf_mirred_put_dev(struct net_device *dev) 410 { 411 dev_put(dev); 412 } 413 414 static struct tc_action_ops act_mirred_ops = { 415 .kind = "mirred", 416 .id = TCA_ID_MIRRED, 417 .owner = THIS_MODULE, 418 .act = tcf_mirred_act, 419 .stats_update = tcf_stats_update, 420 .dump = tcf_mirred_dump, 421 .cleanup = tcf_mirred_release, 422 .init = tcf_mirred_init, 423 .walk = tcf_mirred_walker, 424 .lookup = tcf_mirred_search, 425 .size = sizeof(struct tcf_mirred), 426 .get_dev = tcf_mirred_get_dev, 427 .put_dev = tcf_mirred_put_dev, 428 }; 429 430 static __net_init int mirred_init_net(struct net *net) 431 { 432 struct tc_action_net *tn = net_generic(net, mirred_net_id); 433 434 return tc_action_net_init(tn, &act_mirred_ops); 435 } 436 437 static void __net_exit mirred_exit_net(struct list_head *net_list) 438 { 439 tc_action_net_exit(net_list, mirred_net_id); 440 } 441 442 static struct pernet_operations mirred_net_ops = { 443 .init = mirred_init_net, 444 .exit_batch = mirred_exit_net, 445 .id = &mirred_net_id, 446 .size = sizeof(struct tc_action_net), 447 }; 448 449 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 450 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 451 MODULE_LICENSE("GPL"); 452 453 static int __init mirred_init_module(void) 454 { 455 int err = register_netdevice_notifier(&mirred_device_notifier); 456 if (err) 457 return err; 458 459 pr_info("Mirror/redirect action on\n"); 460 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 461 } 462 463 static void __exit mirred_cleanup_module(void) 464 { 465 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 466 unregister_netdevice_notifier(&mirred_device_notifier); 467 } 468 469 module_init(mirred_init_module); 470 module_exit(mirred_cleanup_module); 471