1 /* 2 * net/sched/act_mirred.c packet mirroring and redirect actions 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Jamal Hadi Salim (2002-4) 10 * 11 * TODO: Add ingress support (and socket redirect support) 12 * 13 */ 14 15 #include <linux/types.h> 16 #include <linux/kernel.h> 17 #include <linux/string.h> 18 #include <linux/errno.h> 19 #include <linux/skbuff.h> 20 #include <linux/rtnetlink.h> 21 #include <linux/module.h> 22 #include <linux/init.h> 23 #include <linux/gfp.h> 24 #include <linux/if_arp.h> 25 #include <net/net_namespace.h> 26 #include <net/netlink.h> 27 #include <net/pkt_sched.h> 28 #include <net/pkt_cls.h> 29 #include <linux/tc_act/tc_mirred.h> 30 #include <net/tc_act/tc_mirred.h> 31 32 static LIST_HEAD(mirred_list); 33 static DEFINE_SPINLOCK(mirred_list_lock); 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 if (dev) 84 dev_put(dev); 85 } 86 87 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 88 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 89 }; 90 91 static unsigned int mirred_net_id; 92 static struct tc_action_ops act_mirred_ops; 93 94 static int tcf_mirred_init(struct net *net, struct nlattr *nla, 95 struct nlattr *est, struct tc_action **a, 96 int ovr, int bind, bool rtnl_held, 97 struct tcf_proto *tp, 98 struct netlink_ext_ack *extack) 99 { 100 struct tc_action_net *tn = net_generic(net, mirred_net_id); 101 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 102 struct tcf_chain *goto_ch = NULL; 103 bool mac_header_xmit = false; 104 struct tc_mirred *parm; 105 struct tcf_mirred *m; 106 struct net_device *dev; 107 bool exists = false; 108 int ret, err; 109 110 if (!nla) { 111 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed"); 112 return -EINVAL; 113 } 114 ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla, 115 mirred_policy, extack); 116 if (ret < 0) 117 return ret; 118 if (!tb[TCA_MIRRED_PARMS]) { 119 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters"); 120 return -EINVAL; 121 } 122 parm = nla_data(tb[TCA_MIRRED_PARMS]); 123 124 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 125 if (err < 0) 126 return err; 127 exists = err; 128 if (exists && bind) 129 return 0; 130 131 switch (parm->eaction) { 132 case TCA_EGRESS_MIRROR: 133 case TCA_EGRESS_REDIR: 134 case TCA_INGRESS_REDIR: 135 case TCA_INGRESS_MIRROR: 136 break; 137 default: 138 if (exists) 139 tcf_idr_release(*a, bind); 140 else 141 tcf_idr_cleanup(tn, parm->index); 142 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 143 return -EINVAL; 144 } 145 146 if (!exists) { 147 if (!parm->ifindex) { 148 tcf_idr_cleanup(tn, parm->index); 149 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 150 return -EINVAL; 151 } 152 ret = tcf_idr_create(tn, parm->index, est, a, 153 &act_mirred_ops, bind, true); 154 if (ret) { 155 tcf_idr_cleanup(tn, parm->index); 156 return ret; 157 } 158 ret = ACT_P_CREATED; 159 } else if (!ovr) { 160 tcf_idr_release(*a, bind); 161 return -EEXIST; 162 } 163 164 m = to_mirred(*a); 165 if (ret == ACT_P_CREATED) 166 INIT_LIST_HEAD(&m->tcfm_list); 167 168 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 169 if (err < 0) 170 goto release_idr; 171 172 spin_lock_bh(&m->tcf_lock); 173 174 if (parm->ifindex) { 175 dev = dev_get_by_index(net, parm->ifindex); 176 if (!dev) { 177 spin_unlock_bh(&m->tcf_lock); 178 err = -ENODEV; 179 goto put_chain; 180 } 181 mac_header_xmit = dev_is_mac_header_xmit(dev); 182 rcu_swap_protected(m->tcfm_dev, dev, 183 lockdep_is_held(&m->tcf_lock)); 184 if (dev) 185 dev_put(dev); 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 tcf_idr_insert(tn, *a); 200 } 201 202 return ret; 203 put_chain: 204 if (goto_ch) 205 tcf_chain_put_by_act(goto_ch); 206 release_idr: 207 tcf_idr_release(*a, bind); 208 return err; 209 } 210 211 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a, 212 struct tcf_result *res) 213 { 214 struct tcf_mirred *m = to_mirred(a); 215 struct sk_buff *skb2 = skb; 216 bool m_mac_header_xmit; 217 struct net_device *dev; 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 tcf_lastuse_update(&m->tcf_tm); 226 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 227 228 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 229 m_eaction = READ_ONCE(m->tcfm_eaction); 230 retval = READ_ONCE(m->tcf_action); 231 dev = rcu_dereference_bh(m->tcfm_dev); 232 if (unlikely(!dev)) { 233 pr_notice_once("tc mirred: target device is gone\n"); 234 goto out; 235 } 236 237 if (unlikely(!(dev->flags & IFF_UP))) { 238 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 239 dev->name); 240 goto out; 241 } 242 243 /* we could easily avoid the clone only if called by ingress and clsact; 244 * since we can't easily detect the clsact caller, skip clone only for 245 * ingress - that covers the TC S/W datapath. 246 */ 247 is_redirect = tcf_mirred_is_act_redirect(m_eaction); 248 use_reinsert = skb_at_tc_ingress(skb) && is_redirect && 249 tcf_mirred_can_reinsert(retval); 250 if (!use_reinsert) { 251 skb2 = skb_clone(skb, GFP_ATOMIC); 252 if (!skb2) 253 goto out; 254 } 255 256 /* If action's target direction differs than filter's direction, 257 * and devices expect a mac header on xmit, then mac push/pull is 258 * needed. 259 */ 260 want_ingress = tcf_mirred_act_wants_ingress(m_eaction); 261 if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) { 262 if (!skb_at_tc_ingress(skb)) { 263 /* caught at egress, act ingress: pull mac */ 264 mac_len = skb_network_header(skb) - skb_mac_header(skb); 265 skb_pull_rcsum(skb2, mac_len); 266 } else { 267 /* caught at ingress, act egress: push mac */ 268 skb_push_rcsum(skb2, skb->mac_len); 269 } 270 } 271 272 skb2->skb_iif = skb->dev->ifindex; 273 skb2->dev = dev; 274 275 /* mirror is always swallowed */ 276 if (is_redirect) { 277 skb2->tc_redirected = 1; 278 skb2->tc_from_ingress = skb2->tc_at_ingress; 279 if (skb2->tc_from_ingress) 280 skb2->tstamp = 0; 281 /* let's the caller reinsert the packet, if possible */ 282 if (use_reinsert) { 283 res->ingress = want_ingress; 284 res->qstats = this_cpu_ptr(m->common.cpu_qstats); 285 return TC_ACT_REINSERT; 286 } 287 } 288 289 if (!want_ingress) 290 err = dev_queue_xmit(skb2); 291 else 292 err = netif_receive_skb(skb2); 293 294 if (err) { 295 out: 296 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); 297 if (tcf_mirred_is_act_redirect(m_eaction)) 298 retval = TC_ACT_SHOT; 299 } 300 301 return retval; 302 } 303 304 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets, 305 u64 lastuse, bool hw) 306 { 307 struct tcf_mirred *m = to_mirred(a); 308 struct tcf_t *tm = &m->tcf_tm; 309 310 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets); 311 if (hw) 312 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw), 313 bytes, packets); 314 tm->lastuse = max_t(u64, tm->lastuse, lastuse); 315 } 316 317 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 318 int ref) 319 { 320 unsigned char *b = skb_tail_pointer(skb); 321 struct tcf_mirred *m = to_mirred(a); 322 struct tc_mirred opt = { 323 .index = m->tcf_index, 324 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 325 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 326 }; 327 struct net_device *dev; 328 struct tcf_t t; 329 330 spin_lock_bh(&m->tcf_lock); 331 opt.action = m->tcf_action; 332 opt.eaction = m->tcfm_eaction; 333 dev = tcf_mirred_dev_dereference(m); 334 if (dev) 335 opt.ifindex = dev->ifindex; 336 337 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 338 goto nla_put_failure; 339 340 tcf_tm_dump(&t, &m->tcf_tm); 341 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 342 goto nla_put_failure; 343 spin_unlock_bh(&m->tcf_lock); 344 345 return skb->len; 346 347 nla_put_failure: 348 spin_unlock_bh(&m->tcf_lock); 349 nlmsg_trim(skb, b); 350 return -1; 351 } 352 353 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 354 struct netlink_callback *cb, int type, 355 const struct tc_action_ops *ops, 356 struct netlink_ext_ack *extack) 357 { 358 struct tc_action_net *tn = net_generic(net, mirred_net_id); 359 360 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 361 } 362 363 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 364 { 365 struct tc_action_net *tn = net_generic(net, mirred_net_id); 366 367 return tcf_idr_search(tn, a, index); 368 } 369 370 static int mirred_device_event(struct notifier_block *unused, 371 unsigned long event, void *ptr) 372 { 373 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 374 struct tcf_mirred *m; 375 376 ASSERT_RTNL(); 377 if (event == NETDEV_UNREGISTER) { 378 spin_lock(&mirred_list_lock); 379 list_for_each_entry(m, &mirred_list, tcfm_list) { 380 spin_lock_bh(&m->tcf_lock); 381 if (tcf_mirred_dev_dereference(m) == dev) { 382 dev_put(dev); 383 /* Note : no rcu grace period necessary, as 384 * net_device are already rcu protected. 385 */ 386 RCU_INIT_POINTER(m->tcfm_dev, NULL); 387 } 388 spin_unlock_bh(&m->tcf_lock); 389 } 390 spin_unlock(&mirred_list_lock); 391 } 392 393 return NOTIFY_DONE; 394 } 395 396 static struct notifier_block mirred_device_notifier = { 397 .notifier_call = mirred_device_event, 398 }; 399 400 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a) 401 { 402 struct tcf_mirred *m = to_mirred(a); 403 struct net_device *dev; 404 405 rcu_read_lock(); 406 dev = rcu_dereference(m->tcfm_dev); 407 if (dev) 408 dev_hold(dev); 409 rcu_read_unlock(); 410 411 return dev; 412 } 413 414 static void tcf_mirred_put_dev(struct net_device *dev) 415 { 416 dev_put(dev); 417 } 418 419 static struct tc_action_ops act_mirred_ops = { 420 .kind = "mirred", 421 .id = TCA_ID_MIRRED, 422 .owner = THIS_MODULE, 423 .act = tcf_mirred_act, 424 .stats_update = tcf_stats_update, 425 .dump = tcf_mirred_dump, 426 .cleanup = tcf_mirred_release, 427 .init = tcf_mirred_init, 428 .walk = tcf_mirred_walker, 429 .lookup = tcf_mirred_search, 430 .size = sizeof(struct tcf_mirred), 431 .get_dev = tcf_mirred_get_dev, 432 .put_dev = tcf_mirred_put_dev, 433 }; 434 435 static __net_init int mirred_init_net(struct net *net) 436 { 437 struct tc_action_net *tn = net_generic(net, mirred_net_id); 438 439 return tc_action_net_init(tn, &act_mirred_ops); 440 } 441 442 static void __net_exit mirred_exit_net(struct list_head *net_list) 443 { 444 tc_action_net_exit(net_list, mirred_net_id); 445 } 446 447 static struct pernet_operations mirred_net_ops = { 448 .init = mirred_init_net, 449 .exit_batch = mirred_exit_net, 450 .id = &mirred_net_id, 451 .size = sizeof(struct tc_action_net), 452 }; 453 454 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 455 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 456 MODULE_LICENSE("GPL"); 457 458 static int __init mirred_init_module(void) 459 { 460 int err = register_netdevice_notifier(&mirred_device_notifier); 461 if (err) 462 return err; 463 464 pr_info("Mirror/redirect action on\n"); 465 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 466 } 467 468 static void __exit mirred_cleanup_module(void) 469 { 470 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 471 unregister_netdevice_notifier(&mirred_device_notifier); 472 } 473 474 module_init(mirred_init_module); 475 module_exit(mirred_cleanup_module); 476