xref: /openbmc/linux/net/sched/act_mirred.c (revision 55fd7e02)
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 #define MIRRED_RECURSION_LIMIT    4
31 static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
32 
33 static bool tcf_mirred_is_act_redirect(int action)
34 {
35 	return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
36 }
37 
38 static bool tcf_mirred_act_wants_ingress(int action)
39 {
40 	switch (action) {
41 	case TCA_EGRESS_REDIR:
42 	case TCA_EGRESS_MIRROR:
43 		return false;
44 	case TCA_INGRESS_REDIR:
45 	case TCA_INGRESS_MIRROR:
46 		return true;
47 	default:
48 		BUG();
49 	}
50 }
51 
52 static bool tcf_mirred_can_reinsert(int action)
53 {
54 	switch (action) {
55 	case TC_ACT_SHOT:
56 	case TC_ACT_STOLEN:
57 	case TC_ACT_QUEUED:
58 	case TC_ACT_TRAP:
59 		return true;
60 	}
61 	return false;
62 }
63 
64 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
65 {
66 	return rcu_dereference_protected(m->tcfm_dev,
67 					 lockdep_is_held(&m->tcf_lock));
68 }
69 
70 static void tcf_mirred_release(struct tc_action *a)
71 {
72 	struct tcf_mirred *m = to_mirred(a);
73 	struct net_device *dev;
74 
75 	spin_lock(&mirred_list_lock);
76 	list_del(&m->tcfm_list);
77 	spin_unlock(&mirred_list_lock);
78 
79 	/* last reference to action, no need to lock */
80 	dev = rcu_dereference_protected(m->tcfm_dev, 1);
81 	if (dev)
82 		dev_put(dev);
83 }
84 
85 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
86 	[TCA_MIRRED_PARMS]	= { .len = sizeof(struct tc_mirred) },
87 };
88 
89 static unsigned int mirred_net_id;
90 static struct tc_action_ops act_mirred_ops;
91 
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,
95 			   struct tcf_proto *tp,
96 			   u32 flags, struct netlink_ext_ack *extack)
97 {
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;
105 	bool exists = false;
106 	int ret, err;
107 	u32 index;
108 
109 	if (!nla) {
110 		NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
111 		return -EINVAL;
112 	}
113 	ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
114 					  mirred_policy, extack);
115 	if (ret < 0)
116 		return ret;
117 	if (!tb[TCA_MIRRED_PARMS]) {
118 		NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
119 		return -EINVAL;
120 	}
121 	parm = nla_data(tb[TCA_MIRRED_PARMS]);
122 	index = parm->index;
123 	err = tcf_idr_check_alloc(tn, &index, a, bind);
124 	if (err < 0)
125 		return err;
126 	exists = err;
127 	if (exists && bind)
128 		return 0;
129 
130 	switch (parm->eaction) {
131 	case TCA_EGRESS_MIRROR:
132 	case TCA_EGRESS_REDIR:
133 	case TCA_INGRESS_REDIR:
134 	case TCA_INGRESS_MIRROR:
135 		break;
136 	default:
137 		if (exists)
138 			tcf_idr_release(*a, bind);
139 		else
140 			tcf_idr_cleanup(tn, index);
141 		NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
142 		return -EINVAL;
143 	}
144 
145 	if (!exists) {
146 		if (!parm->ifindex) {
147 			tcf_idr_cleanup(tn, index);
148 			NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
149 			return -EINVAL;
150 		}
151 		ret = tcf_idr_create_from_flags(tn, index, est, a,
152 						&act_mirred_ops, bind, flags);
153 		if (ret) {
154 			tcf_idr_cleanup(tn, index);
155 			return ret;
156 		}
157 		ret = ACT_P_CREATED;
158 	} else if (!ovr) {
159 		tcf_idr_release(*a, bind);
160 		return -EEXIST;
161 	}
162 
163 	m = to_mirred(*a);
164 	if (ret == ACT_P_CREATED)
165 		INIT_LIST_HEAD(&m->tcfm_list);
166 
167 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
168 	if (err < 0)
169 		goto release_idr;
170 
171 	spin_lock_bh(&m->tcf_lock);
172 
173 	if (parm->ifindex) {
174 		dev = dev_get_by_index(net, parm->ifindex);
175 		if (!dev) {
176 			spin_unlock_bh(&m->tcf_lock);
177 			err = -ENODEV;
178 			goto put_chain;
179 		}
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));
183 		if (dev)
184 			dev_put(dev);
185 		m->tcfm_mac_header_xmit = mac_header_xmit;
186 	}
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);
190 	if (goto_ch)
191 		tcf_chain_put_by_act(goto_ch);
192 
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);
197 
198 		tcf_idr_insert(tn, *a);
199 	}
200 
201 	return ret;
202 put_chain:
203 	if (goto_ch)
204 		tcf_chain_put_by_act(goto_ch);
205 release_idr:
206 	tcf_idr_release(*a, bind);
207 	return err;
208 }
209 
210 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
211 			  struct tcf_result *res)
212 {
213 	struct tcf_mirred *m = to_mirred(a);
214 	struct sk_buff *skb2 = skb;
215 	bool m_mac_header_xmit;
216 	struct net_device *dev;
217 	unsigned int rec_level;
218 	int retval, err = 0;
219 	bool use_reinsert;
220 	bool want_ingress;
221 	bool is_redirect;
222 	bool expects_nh;
223 	int m_eaction;
224 	int mac_len;
225 	bool at_nh;
226 
227 	rec_level = __this_cpu_inc_return(mirred_rec_level);
228 	if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
229 		net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
230 				     netdev_name(skb->dev));
231 		__this_cpu_dec(mirred_rec_level);
232 		return TC_ACT_SHOT;
233 	}
234 
235 	tcf_lastuse_update(&m->tcf_tm);
236 	tcf_action_update_bstats(&m->common, skb);
237 
238 	m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
239 	m_eaction = READ_ONCE(m->tcfm_eaction);
240 	retval = READ_ONCE(m->tcf_action);
241 	dev = rcu_dereference_bh(m->tcfm_dev);
242 	if (unlikely(!dev)) {
243 		pr_notice_once("tc mirred: target device is gone\n");
244 		goto out;
245 	}
246 
247 	if (unlikely(!(dev->flags & IFF_UP))) {
248 		net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
249 				       dev->name);
250 		goto out;
251 	}
252 
253 	/* we could easily avoid the clone only if called by ingress and clsact;
254 	 * since we can't easily detect the clsact caller, skip clone only for
255 	 * ingress - that covers the TC S/W datapath.
256 	 */
257 	is_redirect = tcf_mirred_is_act_redirect(m_eaction);
258 	use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
259 		       tcf_mirred_can_reinsert(retval);
260 	if (!use_reinsert) {
261 		skb2 = skb_clone(skb, GFP_ATOMIC);
262 		if (!skb2)
263 			goto out;
264 	}
265 
266 	want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
267 
268 	expects_nh = want_ingress || !m_mac_header_xmit;
269 	at_nh = skb->data == skb_network_header(skb);
270 	if (at_nh != expects_nh) {
271 		mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
272 			  skb_network_header(skb) - skb_mac_header(skb);
273 		if (expects_nh) {
274 			/* target device/action expect data at nh */
275 			skb_pull_rcsum(skb2, mac_len);
276 		} else {
277 			/* target device/action expect data at mac */
278 			skb_push_rcsum(skb2, mac_len);
279 		}
280 	}
281 
282 	skb2->skb_iif = skb->dev->ifindex;
283 	skb2->dev = dev;
284 
285 	/* mirror is always swallowed */
286 	if (is_redirect) {
287 		skb_set_redirected(skb2, skb2->tc_at_ingress);
288 
289 		/* let's the caller reinsert the packet, if possible */
290 		if (use_reinsert) {
291 			res->ingress = want_ingress;
292 			if (skb_tc_reinsert(skb, res))
293 				tcf_action_inc_overlimit_qstats(&m->common);
294 			__this_cpu_dec(mirred_rec_level);
295 			return TC_ACT_CONSUMED;
296 		}
297 	}
298 
299 	if (!want_ingress)
300 		err = dev_queue_xmit(skb2);
301 	else
302 		err = netif_receive_skb(skb2);
303 
304 	if (err) {
305 out:
306 		tcf_action_inc_overlimit_qstats(&m->common);
307 		if (tcf_mirred_is_act_redirect(m_eaction))
308 			retval = TC_ACT_SHOT;
309 	}
310 	__this_cpu_dec(mirred_rec_level);
311 
312 	return retval;
313 }
314 
315 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
316 			     u64 lastuse, bool hw)
317 {
318 	struct tcf_mirred *m = to_mirred(a);
319 	struct tcf_t *tm = &m->tcf_tm;
320 
321 	tcf_action_update_stats(a, bytes, packets, false, hw);
322 	tm->lastuse = max_t(u64, tm->lastuse, lastuse);
323 }
324 
325 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
326 			   int ref)
327 {
328 	unsigned char *b = skb_tail_pointer(skb);
329 	struct tcf_mirred *m = to_mirred(a);
330 	struct tc_mirred opt = {
331 		.index   = m->tcf_index,
332 		.refcnt  = refcount_read(&m->tcf_refcnt) - ref,
333 		.bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
334 	};
335 	struct net_device *dev;
336 	struct tcf_t t;
337 
338 	spin_lock_bh(&m->tcf_lock);
339 	opt.action = m->tcf_action;
340 	opt.eaction = m->tcfm_eaction;
341 	dev = tcf_mirred_dev_dereference(m);
342 	if (dev)
343 		opt.ifindex = dev->ifindex;
344 
345 	if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
346 		goto nla_put_failure;
347 
348 	tcf_tm_dump(&t, &m->tcf_tm);
349 	if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
350 		goto nla_put_failure;
351 	spin_unlock_bh(&m->tcf_lock);
352 
353 	return skb->len;
354 
355 nla_put_failure:
356 	spin_unlock_bh(&m->tcf_lock);
357 	nlmsg_trim(skb, b);
358 	return -1;
359 }
360 
361 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
362 			     struct netlink_callback *cb, int type,
363 			     const struct tc_action_ops *ops,
364 			     struct netlink_ext_ack *extack)
365 {
366 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
367 
368 	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
369 }
370 
371 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
372 {
373 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
374 
375 	return tcf_idr_search(tn, a, index);
376 }
377 
378 static int mirred_device_event(struct notifier_block *unused,
379 			       unsigned long event, void *ptr)
380 {
381 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
382 	struct tcf_mirred *m;
383 
384 	ASSERT_RTNL();
385 	if (event == NETDEV_UNREGISTER) {
386 		spin_lock(&mirred_list_lock);
387 		list_for_each_entry(m, &mirred_list, tcfm_list) {
388 			spin_lock_bh(&m->tcf_lock);
389 			if (tcf_mirred_dev_dereference(m) == dev) {
390 				dev_put(dev);
391 				/* Note : no rcu grace period necessary, as
392 				 * net_device are already rcu protected.
393 				 */
394 				RCU_INIT_POINTER(m->tcfm_dev, NULL);
395 			}
396 			spin_unlock_bh(&m->tcf_lock);
397 		}
398 		spin_unlock(&mirred_list_lock);
399 	}
400 
401 	return NOTIFY_DONE;
402 }
403 
404 static struct notifier_block mirred_device_notifier = {
405 	.notifier_call = mirred_device_event,
406 };
407 
408 static void tcf_mirred_dev_put(void *priv)
409 {
410 	struct net_device *dev = priv;
411 
412 	dev_put(dev);
413 }
414 
415 static struct net_device *
416 tcf_mirred_get_dev(const struct tc_action *a,
417 		   tc_action_priv_destructor *destructor)
418 {
419 	struct tcf_mirred *m = to_mirred(a);
420 	struct net_device *dev;
421 
422 	rcu_read_lock();
423 	dev = rcu_dereference(m->tcfm_dev);
424 	if (dev) {
425 		dev_hold(dev);
426 		*destructor = tcf_mirred_dev_put;
427 	}
428 	rcu_read_unlock();
429 
430 	return dev;
431 }
432 
433 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
434 {
435 	return nla_total_size(sizeof(struct tc_mirred));
436 }
437 
438 static struct tc_action_ops act_mirred_ops = {
439 	.kind		=	"mirred",
440 	.id		=	TCA_ID_MIRRED,
441 	.owner		=	THIS_MODULE,
442 	.act		=	tcf_mirred_act,
443 	.stats_update	=	tcf_stats_update,
444 	.dump		=	tcf_mirred_dump,
445 	.cleanup	=	tcf_mirred_release,
446 	.init		=	tcf_mirred_init,
447 	.walk		=	tcf_mirred_walker,
448 	.lookup		=	tcf_mirred_search,
449 	.get_fill_size	=	tcf_mirred_get_fill_size,
450 	.size		=	sizeof(struct tcf_mirred),
451 	.get_dev	=	tcf_mirred_get_dev,
452 };
453 
454 static __net_init int mirred_init_net(struct net *net)
455 {
456 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
457 
458 	return tc_action_net_init(net, tn, &act_mirred_ops);
459 }
460 
461 static void __net_exit mirred_exit_net(struct list_head *net_list)
462 {
463 	tc_action_net_exit(net_list, mirred_net_id);
464 }
465 
466 static struct pernet_operations mirred_net_ops = {
467 	.init = mirred_init_net,
468 	.exit_batch = mirred_exit_net,
469 	.id   = &mirred_net_id,
470 	.size = sizeof(struct tc_action_net),
471 };
472 
473 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
474 MODULE_DESCRIPTION("Device Mirror/redirect actions");
475 MODULE_LICENSE("GPL");
476 
477 static int __init mirred_init_module(void)
478 {
479 	int err = register_netdevice_notifier(&mirred_device_notifier);
480 	if (err)
481 		return err;
482 
483 	pr_info("Mirror/redirect action on\n");
484 	err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
485 	if (err)
486 		unregister_netdevice_notifier(&mirred_device_notifier);
487 
488 	return err;
489 }
490 
491 static void __exit mirred_cleanup_module(void)
492 {
493 	tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
494 	unregister_netdevice_notifier(&mirred_device_notifier);
495 }
496 
497 module_init(mirred_init_module);
498 module_exit(mirred_cleanup_module);
499