1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * net/sched/act_mirred.c packet mirroring and redirect actions
5 * Authors: Jamal Hadi Salim (2002-4)
7 * TODO: Add ingress support (and socket redirect support)
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>
27 static LIST_HEAD(mirred_list);
28 static DEFINE_SPINLOCK(mirred_list_lock);
30 #define MIRRED_RECURSION_LIMIT 4
31 static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
33 static bool tcf_mirred_is_act_redirect(int action)
35 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
38 static bool tcf_mirred_act_wants_ingress(int action)
41 case TCA_EGRESS_REDIR:
42 case TCA_EGRESS_MIRROR:
44 case TCA_INGRESS_REDIR:
45 case TCA_INGRESS_MIRROR:
52 static bool tcf_mirred_can_reinsert(int action)
64 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
66 return rcu_dereference_protected(m->tcfm_dev,
67 lockdep_is_held(&m->tcf_lock));
70 static void tcf_mirred_release(struct tc_action *a)
72 struct tcf_mirred *m = to_mirred(a);
73 struct net_device *dev;
75 spin_lock(&mirred_list_lock);
76 list_del(&m->tcfm_list);
77 spin_unlock(&mirred_list_lock);
79 /* last reference to action, no need to lock */
80 dev = rcu_dereference_protected(m->tcfm_dev, 1);
85 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
86 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) },
89 static unsigned int mirred_net_id;
90 static struct tc_action_ops act_mirred_ops;
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,
96 u32 flags, struct netlink_ext_ack *extack)
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;
110 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
113 ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
114 mirred_policy, extack);
117 if (!tb[TCA_MIRRED_PARMS]) {
118 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
121 parm = nla_data(tb[TCA_MIRRED_PARMS]);
123 err = tcf_idr_check_alloc(tn, &index, a, bind);
130 switch (parm->eaction) {
131 case TCA_EGRESS_MIRROR:
132 case TCA_EGRESS_REDIR:
133 case TCA_INGRESS_REDIR:
134 case TCA_INGRESS_MIRROR:
138 tcf_idr_release(*a, bind);
140 tcf_idr_cleanup(tn, index);
141 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
146 if (!parm->ifindex) {
147 tcf_idr_cleanup(tn, index);
148 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
151 ret = tcf_idr_create_from_flags(tn, index, est, a,
152 &act_mirred_ops, bind, flags);
154 tcf_idr_cleanup(tn, index);
159 tcf_idr_release(*a, bind);
164 if (ret == ACT_P_CREATED)
165 INIT_LIST_HEAD(&m->tcfm_list);
167 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
171 spin_lock_bh(&m->tcf_lock);
174 dev = dev_get_by_index(net, parm->ifindex);
176 spin_unlock_bh(&m->tcf_lock);
180 mac_header_xmit = dev_is_mac_header_xmit(dev);
181 dev = rcu_replace_pointer(m->tcfm_dev, dev,
182 lockdep_is_held(&m->tcf_lock));
185 m->tcfm_mac_header_xmit = mac_header_xmit;
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);
191 tcf_chain_put_by_act(goto_ch);
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);
202 tcf_chain_put_by_act(goto_ch);
204 tcf_idr_release(*a, bind);
208 static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
213 err = tcf_dev_queue_xmit(skb, dev_queue_xmit);
215 err = netif_receive_skb(skb);
220 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
221 struct tcf_result *res)
223 struct tcf_mirred *m = to_mirred(a);
224 struct sk_buff *skb2 = skb;
225 bool m_mac_header_xmit;
226 struct net_device *dev;
227 unsigned int rec_level;
237 rec_level = __this_cpu_inc_return(mirred_rec_level);
238 if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
239 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
240 netdev_name(skb->dev));
241 __this_cpu_dec(mirred_rec_level);
245 tcf_lastuse_update(&m->tcf_tm);
246 tcf_action_update_bstats(&m->common, skb);
248 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
249 m_eaction = READ_ONCE(m->tcfm_eaction);
250 retval = READ_ONCE(m->tcf_action);
251 dev = rcu_dereference_bh(m->tcfm_dev);
252 if (unlikely(!dev)) {
253 pr_notice_once("tc mirred: target device is gone\n");
257 if (unlikely(!(dev->flags & IFF_UP))) {
258 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
263 /* we could easily avoid the clone only if called by ingress and clsact;
264 * since we can't easily detect the clsact caller, skip clone only for
265 * ingress - that covers the TC S/W datapath.
267 is_redirect = tcf_mirred_is_act_redirect(m_eaction);
268 use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
269 tcf_mirred_can_reinsert(retval);
271 skb2 = skb_clone(skb, GFP_ATOMIC);
276 want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
278 expects_nh = want_ingress || !m_mac_header_xmit;
279 at_nh = skb->data == skb_network_header(skb);
280 if (at_nh != expects_nh) {
281 mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
282 skb_network_header(skb) - skb_mac_header(skb);
284 /* target device/action expect data at nh */
285 skb_pull_rcsum(skb2, mac_len);
287 /* target device/action expect data at mac */
288 skb_push_rcsum(skb2, mac_len);
292 skb2->skb_iif = skb->dev->ifindex;
295 /* mirror is always swallowed */
297 skb_set_redirected(skb2, skb2->tc_at_ingress);
299 /* let's the caller reinsert the packet, if possible */
301 res->ingress = want_ingress;
302 err = tcf_mirred_forward(res->ingress, skb);
304 tcf_action_inc_overlimit_qstats(&m->common);
305 __this_cpu_dec(mirred_rec_level);
306 return TC_ACT_CONSUMED;
310 err = tcf_mirred_forward(want_ingress, skb2);
313 tcf_action_inc_overlimit_qstats(&m->common);
314 if (tcf_mirred_is_act_redirect(m_eaction))
315 retval = TC_ACT_SHOT;
317 __this_cpu_dec(mirred_rec_level);
322 static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
323 u64 drops, u64 lastuse, bool hw)
325 struct tcf_mirred *m = to_mirred(a);
326 struct tcf_t *tm = &m->tcf_tm;
328 tcf_action_update_stats(a, bytes, packets, drops, hw);
329 tm->lastuse = max_t(u64, tm->lastuse, lastuse);
332 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
335 unsigned char *b = skb_tail_pointer(skb);
336 struct tcf_mirred *m = to_mirred(a);
337 struct tc_mirred opt = {
338 .index = m->tcf_index,
339 .refcnt = refcount_read(&m->tcf_refcnt) - ref,
340 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
342 struct net_device *dev;
345 spin_lock_bh(&m->tcf_lock);
346 opt.action = m->tcf_action;
347 opt.eaction = m->tcfm_eaction;
348 dev = tcf_mirred_dev_dereference(m);
350 opt.ifindex = dev->ifindex;
352 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
353 goto nla_put_failure;
355 tcf_tm_dump(&t, &m->tcf_tm);
356 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
357 goto nla_put_failure;
358 spin_unlock_bh(&m->tcf_lock);
363 spin_unlock_bh(&m->tcf_lock);
368 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
369 struct netlink_callback *cb, int type,
370 const struct tc_action_ops *ops,
371 struct netlink_ext_ack *extack)
373 struct tc_action_net *tn = net_generic(net, mirred_net_id);
375 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
378 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
380 struct tc_action_net *tn = net_generic(net, mirred_net_id);
382 return tcf_idr_search(tn, a, index);
385 static int mirred_device_event(struct notifier_block *unused,
386 unsigned long event, void *ptr)
388 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
389 struct tcf_mirred *m;
392 if (event == NETDEV_UNREGISTER) {
393 spin_lock(&mirred_list_lock);
394 list_for_each_entry(m, &mirred_list, tcfm_list) {
395 spin_lock_bh(&m->tcf_lock);
396 if (tcf_mirred_dev_dereference(m) == dev) {
398 /* Note : no rcu grace period necessary, as
399 * net_device are already rcu protected.
401 RCU_INIT_POINTER(m->tcfm_dev, NULL);
403 spin_unlock_bh(&m->tcf_lock);
405 spin_unlock(&mirred_list_lock);
411 static struct notifier_block mirred_device_notifier = {
412 .notifier_call = mirred_device_event,
415 static void tcf_mirred_dev_put(void *priv)
417 struct net_device *dev = priv;
422 static struct net_device *
423 tcf_mirred_get_dev(const struct tc_action *a,
424 tc_action_priv_destructor *destructor)
426 struct tcf_mirred *m = to_mirred(a);
427 struct net_device *dev;
430 dev = rcu_dereference(m->tcfm_dev);
433 *destructor = tcf_mirred_dev_put;
440 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
442 return nla_total_size(sizeof(struct tc_mirred));
445 static struct tc_action_ops act_mirred_ops = {
448 .owner = THIS_MODULE,
449 .act = tcf_mirred_act,
450 .stats_update = tcf_stats_update,
451 .dump = tcf_mirred_dump,
452 .cleanup = tcf_mirred_release,
453 .init = tcf_mirred_init,
454 .walk = tcf_mirred_walker,
455 .lookup = tcf_mirred_search,
456 .get_fill_size = tcf_mirred_get_fill_size,
457 .size = sizeof(struct tcf_mirred),
458 .get_dev = tcf_mirred_get_dev,
461 static __net_init int mirred_init_net(struct net *net)
463 struct tc_action_net *tn = net_generic(net, mirred_net_id);
465 return tc_action_net_init(net, tn, &act_mirred_ops);
468 static void __net_exit mirred_exit_net(struct list_head *net_list)
470 tc_action_net_exit(net_list, mirred_net_id);
473 static struct pernet_operations mirred_net_ops = {
474 .init = mirred_init_net,
475 .exit_batch = mirred_exit_net,
476 .id = &mirred_net_id,
477 .size = sizeof(struct tc_action_net),
480 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
481 MODULE_DESCRIPTION("Device Mirror/redirect actions");
482 MODULE_LICENSE("GPL");
484 static int __init mirred_init_module(void)
486 int err = register_netdevice_notifier(&mirred_device_notifier);
490 pr_info("Mirror/redirect action on\n");
491 err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
493 unregister_netdevice_notifier(&mirred_device_notifier);
498 static void __exit mirred_cleanup_module(void)
500 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
501 unregister_netdevice_notifier(&mirred_device_notifier);
504 module_init(mirred_init_module);
505 module_exit(mirred_cleanup_module);