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_act(struct sk_buff *skb, const struct tc_action *a,
209 struct tcf_result *res)
211 struct tcf_mirred *m = to_mirred(a);
212 struct sk_buff *skb2 = skb;
213 bool m_mac_header_xmit;
214 struct net_device *dev;
215 unsigned int rec_level;
225 rec_level = __this_cpu_inc_return(mirred_rec_level);
226 if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
227 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
228 netdev_name(skb->dev));
229 __this_cpu_dec(mirred_rec_level);
233 tcf_lastuse_update(&m->tcf_tm);
234 tcf_action_update_bstats(&m->common, skb);
236 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
237 m_eaction = READ_ONCE(m->tcfm_eaction);
238 retval = READ_ONCE(m->tcf_action);
239 dev = rcu_dereference_bh(m->tcfm_dev);
240 if (unlikely(!dev)) {
241 pr_notice_once("tc mirred: target device is gone\n");
245 if (unlikely(!(dev->flags & IFF_UP))) {
246 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
251 /* we could easily avoid the clone only if called by ingress and clsact;
252 * since we can't easily detect the clsact caller, skip clone only for
253 * ingress - that covers the TC S/W datapath.
255 is_redirect = tcf_mirred_is_act_redirect(m_eaction);
256 use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
257 tcf_mirred_can_reinsert(retval);
259 skb2 = skb_clone(skb, GFP_ATOMIC);
264 want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
266 expects_nh = want_ingress || !m_mac_header_xmit;
267 at_nh = skb->data == skb_network_header(skb);
268 if (at_nh != expects_nh) {
269 mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
270 skb_network_header(skb) - skb_mac_header(skb);
272 /* target device/action expect data at nh */
273 skb_pull_rcsum(skb2, mac_len);
275 /* target device/action expect data at mac */
276 skb_push_rcsum(skb2, mac_len);
280 skb2->skb_iif = skb->dev->ifindex;
283 /* mirror is always swallowed */
285 skb_set_redirected(skb2, skb2->tc_at_ingress);
287 /* let's the caller reinsert the packet, if possible */
289 res->ingress = want_ingress;
290 if (skb_tc_reinsert(skb, res))
291 tcf_action_inc_overlimit_qstats(&m->common);
292 __this_cpu_dec(mirred_rec_level);
293 return TC_ACT_CONSUMED;
298 err = dev_queue_xmit(skb2);
300 err = netif_receive_skb(skb2);
304 tcf_action_inc_overlimit_qstats(&m->common);
305 if (tcf_mirred_is_act_redirect(m_eaction))
306 retval = TC_ACT_SHOT;
308 __this_cpu_dec(mirred_rec_level);
313 static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
314 u64 drops, u64 lastuse, bool hw)
316 struct tcf_mirred *m = to_mirred(a);
317 struct tcf_t *tm = &m->tcf_tm;
319 tcf_action_update_stats(a, bytes, packets, drops, hw);
320 tm->lastuse = max_t(u64, tm->lastuse, lastuse);
323 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
326 unsigned char *b = skb_tail_pointer(skb);
327 struct tcf_mirred *m = to_mirred(a);
328 struct tc_mirred opt = {
329 .index = m->tcf_index,
330 .refcnt = refcount_read(&m->tcf_refcnt) - ref,
331 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
333 struct net_device *dev;
336 spin_lock_bh(&m->tcf_lock);
337 opt.action = m->tcf_action;
338 opt.eaction = m->tcfm_eaction;
339 dev = tcf_mirred_dev_dereference(m);
341 opt.ifindex = dev->ifindex;
343 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
344 goto nla_put_failure;
346 tcf_tm_dump(&t, &m->tcf_tm);
347 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
348 goto nla_put_failure;
349 spin_unlock_bh(&m->tcf_lock);
354 spin_unlock_bh(&m->tcf_lock);
359 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
360 struct netlink_callback *cb, int type,
361 const struct tc_action_ops *ops,
362 struct netlink_ext_ack *extack)
364 struct tc_action_net *tn = net_generic(net, mirred_net_id);
366 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
369 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
371 struct tc_action_net *tn = net_generic(net, mirred_net_id);
373 return tcf_idr_search(tn, a, index);
376 static int mirred_device_event(struct notifier_block *unused,
377 unsigned long event, void *ptr)
379 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
380 struct tcf_mirred *m;
383 if (event == NETDEV_UNREGISTER) {
384 spin_lock(&mirred_list_lock);
385 list_for_each_entry(m, &mirred_list, tcfm_list) {
386 spin_lock_bh(&m->tcf_lock);
387 if (tcf_mirred_dev_dereference(m) == dev) {
389 /* Note : no rcu grace period necessary, as
390 * net_device are already rcu protected.
392 RCU_INIT_POINTER(m->tcfm_dev, NULL);
394 spin_unlock_bh(&m->tcf_lock);
396 spin_unlock(&mirred_list_lock);
402 static struct notifier_block mirred_device_notifier = {
403 .notifier_call = mirred_device_event,
406 static void tcf_mirred_dev_put(void *priv)
408 struct net_device *dev = priv;
413 static struct net_device *
414 tcf_mirred_get_dev(const struct tc_action *a,
415 tc_action_priv_destructor *destructor)
417 struct tcf_mirred *m = to_mirred(a);
418 struct net_device *dev;
421 dev = rcu_dereference(m->tcfm_dev);
424 *destructor = tcf_mirred_dev_put;
431 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
433 return nla_total_size(sizeof(struct tc_mirred));
436 static struct tc_action_ops act_mirred_ops = {
439 .owner = THIS_MODULE,
440 .act = tcf_mirred_act,
441 .stats_update = tcf_stats_update,
442 .dump = tcf_mirred_dump,
443 .cleanup = tcf_mirred_release,
444 .init = tcf_mirred_init,
445 .walk = tcf_mirred_walker,
446 .lookup = tcf_mirred_search,
447 .get_fill_size = tcf_mirred_get_fill_size,
448 .size = sizeof(struct tcf_mirred),
449 .get_dev = tcf_mirred_get_dev,
452 static __net_init int mirred_init_net(struct net *net)
454 struct tc_action_net *tn = net_generic(net, mirred_net_id);
456 return tc_action_net_init(net, tn, &act_mirred_ops);
459 static void __net_exit mirred_exit_net(struct list_head *net_list)
461 tc_action_net_exit(net_list, mirred_net_id);
464 static struct pernet_operations mirred_net_ops = {
465 .init = mirred_init_net,
466 .exit_batch = mirred_exit_net,
467 .id = &mirred_net_id,
468 .size = sizeof(struct tc_action_net),
471 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
472 MODULE_DESCRIPTION("Device Mirror/redirect actions");
473 MODULE_LICENSE("GPL");
475 static int __init mirred_init_module(void)
477 int err = register_netdevice_notifier(&mirred_device_notifier);
481 pr_info("Mirror/redirect action on\n");
482 err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
484 unregister_netdevice_notifier(&mirred_device_notifier);
489 static void __exit mirred_cleanup_module(void)
491 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
492 unregister_netdevice_notifier(&mirred_device_notifier);
495 module_init(mirred_init_module);
496 module_exit(mirred_cleanup_module);