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 netlink_ext_ack *extack) 98 { 99 struct tc_action_net *tn = net_generic(net, mirred_net_id); 100 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 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; 107 108 if (!nla) { 109 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed"); 110 return -EINVAL; 111 } 112 ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack); 113 if (ret < 0) 114 return ret; 115 if (!tb[TCA_MIRRED_PARMS]) { 116 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters"); 117 return -EINVAL; 118 } 119 parm = nla_data(tb[TCA_MIRRED_PARMS]); 120 121 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 122 if (err < 0) 123 return err; 124 exists = err; 125 if (exists && bind) 126 return 0; 127 128 switch (parm->eaction) { 129 case TCA_EGRESS_MIRROR: 130 case TCA_EGRESS_REDIR: 131 case TCA_INGRESS_REDIR: 132 case TCA_INGRESS_MIRROR: 133 break; 134 default: 135 if (exists) 136 tcf_idr_release(*a, bind); 137 else 138 tcf_idr_cleanup(tn, parm->index); 139 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 140 return -EINVAL; 141 } 142 143 if (!exists) { 144 if (!parm->ifindex) { 145 tcf_idr_cleanup(tn, parm->index); 146 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 147 return -EINVAL; 148 } 149 ret = tcf_idr_create(tn, parm->index, est, a, 150 &act_mirred_ops, bind, true); 151 if (ret) { 152 tcf_idr_cleanup(tn, parm->index); 153 return ret; 154 } 155 ret = ACT_P_CREATED; 156 } else if (!ovr) { 157 tcf_idr_release(*a, bind); 158 return -EEXIST; 159 } 160 m = to_mirred(*a); 161 162 spin_lock_bh(&m->tcf_lock); 163 m->tcf_action = parm->action; 164 m->tcfm_eaction = parm->eaction; 165 166 if (parm->ifindex) { 167 dev = dev_get_by_index(net, parm->ifindex); 168 if (!dev) { 169 spin_unlock_bh(&m->tcf_lock); 170 tcf_idr_release(*a, bind); 171 return -ENODEV; 172 } 173 mac_header_xmit = dev_is_mac_header_xmit(dev); 174 rcu_swap_protected(m->tcfm_dev, dev, 175 lockdep_is_held(&m->tcf_lock)); 176 if (dev) 177 dev_put(dev); 178 m->tcfm_mac_header_xmit = mac_header_xmit; 179 } 180 spin_unlock_bh(&m->tcf_lock); 181 182 if (ret == ACT_P_CREATED) { 183 spin_lock(&mirred_list_lock); 184 list_add(&m->tcfm_list, &mirred_list); 185 spin_unlock(&mirred_list_lock); 186 187 tcf_idr_insert(tn, *a); 188 } 189 190 return ret; 191 } 192 193 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a, 194 struct tcf_result *res) 195 { 196 struct tcf_mirred *m = to_mirred(a); 197 struct sk_buff *skb2 = skb; 198 bool m_mac_header_xmit; 199 struct net_device *dev; 200 int retval, err = 0; 201 bool use_reinsert; 202 bool want_ingress; 203 bool is_redirect; 204 int m_eaction; 205 int mac_len; 206 207 tcf_lastuse_update(&m->tcf_tm); 208 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 209 210 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 211 m_eaction = READ_ONCE(m->tcfm_eaction); 212 retval = READ_ONCE(m->tcf_action); 213 dev = rcu_dereference_bh(m->tcfm_dev); 214 if (unlikely(!dev)) { 215 pr_notice_once("tc mirred: target device is gone\n"); 216 goto out; 217 } 218 219 if (unlikely(!(dev->flags & IFF_UP))) { 220 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 221 dev->name); 222 goto out; 223 } 224 225 /* we could easily avoid the clone only if called by ingress and clsact; 226 * since we can't easily detect the clsact caller, skip clone only for 227 * ingress - that covers the TC S/W datapath. 228 */ 229 is_redirect = tcf_mirred_is_act_redirect(m_eaction); 230 use_reinsert = skb_at_tc_ingress(skb) && is_redirect && 231 tcf_mirred_can_reinsert(retval); 232 if (!use_reinsert) { 233 skb2 = skb_clone(skb, GFP_ATOMIC); 234 if (!skb2) 235 goto out; 236 } 237 238 /* If action's target direction differs than filter's direction, 239 * and devices expect a mac header on xmit, then mac push/pull is 240 * needed. 241 */ 242 want_ingress = tcf_mirred_act_wants_ingress(m_eaction); 243 if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) { 244 if (!skb_at_tc_ingress(skb)) { 245 /* caught at egress, act ingress: pull mac */ 246 mac_len = skb_network_header(skb) - skb_mac_header(skb); 247 skb_pull_rcsum(skb2, mac_len); 248 } else { 249 /* caught at ingress, act egress: push mac */ 250 skb_push_rcsum(skb2, skb->mac_len); 251 } 252 } 253 254 skb2->skb_iif = skb->dev->ifindex; 255 skb2->dev = dev; 256 257 /* mirror is always swallowed */ 258 if (is_redirect) { 259 skb2->tc_redirected = 1; 260 skb2->tc_from_ingress = skb2->tc_at_ingress; 261 262 /* let's the caller reinsert the packet, if possible */ 263 if (use_reinsert) { 264 res->ingress = want_ingress; 265 res->qstats = this_cpu_ptr(m->common.cpu_qstats); 266 return TC_ACT_REINSERT; 267 } 268 } 269 270 if (!want_ingress) 271 err = dev_queue_xmit(skb2); 272 else 273 err = netif_receive_skb(skb2); 274 275 if (err) { 276 out: 277 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); 278 if (tcf_mirred_is_act_redirect(m_eaction)) 279 retval = TC_ACT_SHOT; 280 } 281 282 return retval; 283 } 284 285 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets, 286 u64 lastuse, bool hw) 287 { 288 struct tcf_mirred *m = to_mirred(a); 289 struct tcf_t *tm = &m->tcf_tm; 290 291 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets); 292 if (hw) 293 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw), 294 bytes, packets); 295 tm->lastuse = max_t(u64, tm->lastuse, lastuse); 296 } 297 298 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 299 int ref) 300 { 301 unsigned char *b = skb_tail_pointer(skb); 302 struct tcf_mirred *m = to_mirred(a); 303 struct tc_mirred opt = { 304 .index = m->tcf_index, 305 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 306 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 307 }; 308 struct net_device *dev; 309 struct tcf_t t; 310 311 spin_lock_bh(&m->tcf_lock); 312 opt.action = m->tcf_action; 313 opt.eaction = m->tcfm_eaction; 314 dev = tcf_mirred_dev_dereference(m); 315 if (dev) 316 opt.ifindex = dev->ifindex; 317 318 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 319 goto nla_put_failure; 320 321 tcf_tm_dump(&t, &m->tcf_tm); 322 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 323 goto nla_put_failure; 324 spin_unlock_bh(&m->tcf_lock); 325 326 return skb->len; 327 328 nla_put_failure: 329 spin_unlock_bh(&m->tcf_lock); 330 nlmsg_trim(skb, b); 331 return -1; 332 } 333 334 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 335 struct netlink_callback *cb, int type, 336 const struct tc_action_ops *ops, 337 struct netlink_ext_ack *extack) 338 { 339 struct tc_action_net *tn = net_generic(net, mirred_net_id); 340 341 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 342 } 343 344 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 345 { 346 struct tc_action_net *tn = net_generic(net, mirred_net_id); 347 348 return tcf_idr_search(tn, a, index); 349 } 350 351 static int mirred_device_event(struct notifier_block *unused, 352 unsigned long event, void *ptr) 353 { 354 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 355 struct tcf_mirred *m; 356 357 ASSERT_RTNL(); 358 if (event == NETDEV_UNREGISTER) { 359 spin_lock(&mirred_list_lock); 360 list_for_each_entry(m, &mirred_list, tcfm_list) { 361 spin_lock_bh(&m->tcf_lock); 362 if (tcf_mirred_dev_dereference(m) == dev) { 363 dev_put(dev); 364 /* Note : no rcu grace period necessary, as 365 * net_device are already rcu protected. 366 */ 367 RCU_INIT_POINTER(m->tcfm_dev, NULL); 368 } 369 spin_unlock_bh(&m->tcf_lock); 370 } 371 spin_unlock(&mirred_list_lock); 372 } 373 374 return NOTIFY_DONE; 375 } 376 377 static struct notifier_block mirred_device_notifier = { 378 .notifier_call = mirred_device_event, 379 }; 380 381 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a) 382 { 383 struct tcf_mirred *m = to_mirred(a); 384 struct net_device *dev; 385 386 rcu_read_lock(); 387 dev = rcu_dereference(m->tcfm_dev); 388 if (dev) 389 dev_hold(dev); 390 rcu_read_unlock(); 391 392 return dev; 393 } 394 395 static void tcf_mirred_put_dev(struct net_device *dev) 396 { 397 dev_put(dev); 398 } 399 400 static struct tc_action_ops act_mirred_ops = { 401 .kind = "mirred", 402 .type = TCA_ACT_MIRRED, 403 .owner = THIS_MODULE, 404 .act = tcf_mirred_act, 405 .stats_update = tcf_stats_update, 406 .dump = tcf_mirred_dump, 407 .cleanup = tcf_mirred_release, 408 .init = tcf_mirred_init, 409 .walk = tcf_mirred_walker, 410 .lookup = tcf_mirred_search, 411 .size = sizeof(struct tcf_mirred), 412 .get_dev = tcf_mirred_get_dev, 413 .put_dev = tcf_mirred_put_dev, 414 }; 415 416 static __net_init int mirred_init_net(struct net *net) 417 { 418 struct tc_action_net *tn = net_generic(net, mirred_net_id); 419 420 return tc_action_net_init(tn, &act_mirred_ops); 421 } 422 423 static void __net_exit mirred_exit_net(struct list_head *net_list) 424 { 425 tc_action_net_exit(net_list, mirred_net_id); 426 } 427 428 static struct pernet_operations mirred_net_ops = { 429 .init = mirred_init_net, 430 .exit_batch = mirred_exit_net, 431 .id = &mirred_net_id, 432 .size = sizeof(struct tc_action_net), 433 }; 434 435 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 436 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 437 MODULE_LICENSE("GPL"); 438 439 static int __init mirred_init_module(void) 440 { 441 int err = register_netdevice_notifier(&mirred_device_notifier); 442 if (err) 443 return err; 444 445 pr_info("Mirror/redirect action on\n"); 446 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 447 } 448 449 static void __exit mirred_cleanup_module(void) 450 { 451 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 452 unregister_netdevice_notifier(&mirred_device_notifier); 453 } 454 455 module_init(mirred_init_module); 456 module_exit(mirred_cleanup_module); 457