xref: /openbmc/linux/net/sched/act_mirred.c (revision b593bce5) 
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 			   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 
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_deprecated(tb, TCA_MIRRED_MAX, nla,
113 					  mirred_policy, extack);
114 	if (ret < 0)
115 		return ret;
116 	if (!tb[TCA_MIRRED_PARMS]) {
117 		NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
118 		return -EINVAL;
119 	}
120 	parm = nla_data(tb[TCA_MIRRED_PARMS]);
121 
122 	err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
123 	if (err < 0)
124 		return err;
125 	exists = err;
126 	if (exists && bind)
127 		return 0;
128 
129 	switch (parm->eaction) {
130 	case TCA_EGRESS_MIRROR:
131 	case TCA_EGRESS_REDIR:
132 	case TCA_INGRESS_REDIR:
133 	case TCA_INGRESS_MIRROR:
134 		break;
135 	default:
136 		if (exists)
137 			tcf_idr_release(*a, bind);
138 		else
139 			tcf_idr_cleanup(tn, parm->index);
140 		NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
141 		return -EINVAL;
142 	}
143 
144 	if (!exists) {
145 		if (!parm->ifindex) {
146 			tcf_idr_cleanup(tn, parm->index);
147 			NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
148 			return -EINVAL;
149 		}
150 		ret = tcf_idr_create(tn, parm->index, est, a,
151 				     &act_mirred_ops, bind, true);
152 		if (ret) {
153 			tcf_idr_cleanup(tn, parm->index);
154 			return ret;
155 		}
156 		ret = ACT_P_CREATED;
157 	} else if (!ovr) {
158 		tcf_idr_release(*a, bind);
159 		return -EEXIST;
160 	}
161 
162 	m = to_mirred(*a);
163 	if (ret == ACT_P_CREATED)
164 		INIT_LIST_HEAD(&m->tcfm_list);
165 
166 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
167 	if (err < 0)
168 		goto release_idr;
169 
170 	spin_lock_bh(&m->tcf_lock);
171 
172 	if (parm->ifindex) {
173 		dev = dev_get_by_index(net, parm->ifindex);
174 		if (!dev) {
175 			spin_unlock_bh(&m->tcf_lock);
176 			err = -ENODEV;
177 			goto put_chain;
178 		}
179 		mac_header_xmit = dev_is_mac_header_xmit(dev);
180 		rcu_swap_protected(m->tcfm_dev, dev,
181 				   lockdep_is_held(&m->tcf_lock));
182 		if (dev)
183 			dev_put(dev);
184 		m->tcfm_mac_header_xmit = mac_header_xmit;
185 	}
186 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
187 	m->tcfm_eaction = parm->eaction;
188 	spin_unlock_bh(&m->tcf_lock);
189 	if (goto_ch)
190 		tcf_chain_put_by_act(goto_ch);
191 
192 	if (ret == ACT_P_CREATED) {
193 		spin_lock(&mirred_list_lock);
194 		list_add(&m->tcfm_list, &mirred_list);
195 		spin_unlock(&mirred_list_lock);
196 
197 		tcf_idr_insert(tn, *a);
198 	}
199 
200 	return ret;
201 put_chain:
202 	if (goto_ch)
203 		tcf_chain_put_by_act(goto_ch);
204 release_idr:
205 	tcf_idr_release(*a, bind);
206 	return err;
207 }
208 
209 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
210 			  struct tcf_result *res)
211 {
212 	struct tcf_mirred *m = to_mirred(a);
213 	struct sk_buff *skb2 = skb;
214 	bool m_mac_header_xmit;
215 	struct net_device *dev;
216 	unsigned int rec_level;
217 	int retval, err = 0;
218 	bool use_reinsert;
219 	bool want_ingress;
220 	bool is_redirect;
221 	int m_eaction;
222 	int mac_len;
223 
224 	rec_level = __this_cpu_inc_return(mirred_rec_level);
225 	if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
226 		net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
227 				     netdev_name(skb->dev));
228 		__this_cpu_dec(mirred_rec_level);
229 		return TC_ACT_SHOT;
230 	}
231 
232 	tcf_lastuse_update(&m->tcf_tm);
233 	bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
234 
235 	m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
236 	m_eaction = READ_ONCE(m->tcfm_eaction);
237 	retval = READ_ONCE(m->tcf_action);
238 	dev = rcu_dereference_bh(m->tcfm_dev);
239 	if (unlikely(!dev)) {
240 		pr_notice_once("tc mirred: target device is gone\n");
241 		goto out;
242 	}
243 
244 	if (unlikely(!(dev->flags & IFF_UP))) {
245 		net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
246 				       dev->name);
247 		goto out;
248 	}
249 
250 	/* we could easily avoid the clone only if called by ingress and clsact;
251 	 * since we can't easily detect the clsact caller, skip clone only for
252 	 * ingress - that covers the TC S/W datapath.
253 	 */
254 	is_redirect = tcf_mirred_is_act_redirect(m_eaction);
255 	use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
256 		       tcf_mirred_can_reinsert(retval);
257 	if (!use_reinsert) {
258 		skb2 = skb_clone(skb, GFP_ATOMIC);
259 		if (!skb2)
260 			goto out;
261 	}
262 
263 	/* If action's target direction differs than filter's direction,
264 	 * and devices expect a mac header on xmit, then mac push/pull is
265 	 * needed.
266 	 */
267 	want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
268 	if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) {
269 		if (!skb_at_tc_ingress(skb)) {
270 			/* caught at egress, act ingress: pull mac */
271 			mac_len = skb_network_header(skb) - skb_mac_header(skb);
272 			skb_pull_rcsum(skb2, mac_len);
273 		} else {
274 			/* caught at ingress, act egress: push mac */
275 			skb_push_rcsum(skb2, skb->mac_len);
276 		}
277 	}
278 
279 	skb2->skb_iif = skb->dev->ifindex;
280 	skb2->dev = dev;
281 
282 	/* mirror is always swallowed */
283 	if (is_redirect) {
284 		skb2->tc_redirected = 1;
285 		skb2->tc_from_ingress = skb2->tc_at_ingress;
286 		if (skb2->tc_from_ingress)
287 			skb2->tstamp = 0;
288 		/* let's the caller reinsert the packet, if possible */
289 		if (use_reinsert) {
290 			res->ingress = want_ingress;
291 			res->qstats = this_cpu_ptr(m->common.cpu_qstats);
292 			skb_tc_reinsert(skb, res);
293 			__this_cpu_dec(mirred_rec_level);
294 			return TC_ACT_CONSUMED;
295 		}
296 	}
297 
298 	if (!want_ingress)
299 		err = dev_queue_xmit(skb2);
300 	else
301 		err = netif_receive_skb(skb2);
302 
303 	if (err) {
304 out:
305 		qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
306 		if (tcf_mirred_is_act_redirect(m_eaction))
307 			retval = TC_ACT_SHOT;
308 	}
309 	__this_cpu_dec(mirred_rec_level);
310 
311 	return retval;
312 }
313 
314 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
315 			     u64 lastuse, bool hw)
316 {
317 	struct tcf_mirred *m = to_mirred(a);
318 	struct tcf_t *tm = &m->tcf_tm;
319 
320 	_bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
321 	if (hw)
322 		_bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw),
323 				   bytes, packets);
324 	tm->lastuse = max_t(u64, tm->lastuse, lastuse);
325 }
326 
327 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
328 			   int ref)
329 {
330 	unsigned char *b = skb_tail_pointer(skb);
331 	struct tcf_mirred *m = to_mirred(a);
332 	struct tc_mirred opt = {
333 		.index   = m->tcf_index,
334 		.refcnt  = refcount_read(&m->tcf_refcnt) - ref,
335 		.bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
336 	};
337 	struct net_device *dev;
338 	struct tcf_t t;
339 
340 	spin_lock_bh(&m->tcf_lock);
341 	opt.action = m->tcf_action;
342 	opt.eaction = m->tcfm_eaction;
343 	dev = tcf_mirred_dev_dereference(m);
344 	if (dev)
345 		opt.ifindex = dev->ifindex;
346 
347 	if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
348 		goto nla_put_failure;
349 
350 	tcf_tm_dump(&t, &m->tcf_tm);
351 	if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
352 		goto nla_put_failure;
353 	spin_unlock_bh(&m->tcf_lock);
354 
355 	return skb->len;
356 
357 nla_put_failure:
358 	spin_unlock_bh(&m->tcf_lock);
359 	nlmsg_trim(skb, b);
360 	return -1;
361 }
362 
363 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
364 			     struct netlink_callback *cb, int type,
365 			     const struct tc_action_ops *ops,
366 			     struct netlink_ext_ack *extack)
367 {
368 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
369 
370 	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
371 }
372 
373 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
374 {
375 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
376 
377 	return tcf_idr_search(tn, a, index);
378 }
379 
380 static int mirred_device_event(struct notifier_block *unused,
381 			       unsigned long event, void *ptr)
382 {
383 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
384 	struct tcf_mirred *m;
385 
386 	ASSERT_RTNL();
387 	if (event == NETDEV_UNREGISTER) {
388 		spin_lock(&mirred_list_lock);
389 		list_for_each_entry(m, &mirred_list, tcfm_list) {
390 			spin_lock_bh(&m->tcf_lock);
391 			if (tcf_mirred_dev_dereference(m) == dev) {
392 				dev_put(dev);
393 				/* Note : no rcu grace period necessary, as
394 				 * net_device are already rcu protected.
395 				 */
396 				RCU_INIT_POINTER(m->tcfm_dev, NULL);
397 			}
398 			spin_unlock_bh(&m->tcf_lock);
399 		}
400 		spin_unlock(&mirred_list_lock);
401 	}
402 
403 	return NOTIFY_DONE;
404 }
405 
406 static struct notifier_block mirred_device_notifier = {
407 	.notifier_call = mirred_device_event,
408 };
409 
410 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
411 {
412 	struct tcf_mirred *m = to_mirred(a);
413 	struct net_device *dev;
414 
415 	rcu_read_lock();
416 	dev = rcu_dereference(m->tcfm_dev);
417 	if (dev)
418 		dev_hold(dev);
419 	rcu_read_unlock();
420 
421 	return dev;
422 }
423 
424 static void tcf_mirred_put_dev(struct net_device *dev)
425 {
426 	dev_put(dev);
427 }
428 
429 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
430 {
431 	return nla_total_size(sizeof(struct tc_mirred));
432 }
433 
434 static struct tc_action_ops act_mirred_ops = {
435 	.kind		=	"mirred",
436 	.id		=	TCA_ID_MIRRED,
437 	.owner		=	THIS_MODULE,
438 	.act		=	tcf_mirred_act,
439 	.stats_update	=	tcf_stats_update,
440 	.dump		=	tcf_mirred_dump,
441 	.cleanup	=	tcf_mirred_release,
442 	.init		=	tcf_mirred_init,
443 	.walk		=	tcf_mirred_walker,
444 	.lookup		=	tcf_mirred_search,
445 	.get_fill_size	=	tcf_mirred_get_fill_size,
446 	.size		=	sizeof(struct tcf_mirred),
447 	.get_dev	=	tcf_mirred_get_dev,
448 	.put_dev	=	tcf_mirred_put_dev,
449 };
450 
451 static __net_init int mirred_init_net(struct net *net)
452 {
453 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
454 
455 	return tc_action_net_init(tn, &act_mirred_ops);
456 }
457 
458 static void __net_exit mirred_exit_net(struct list_head *net_list)
459 {
460 	tc_action_net_exit(net_list, mirred_net_id);
461 }
462 
463 static struct pernet_operations mirred_net_ops = {
464 	.init = mirred_init_net,
465 	.exit_batch = mirred_exit_net,
466 	.id   = &mirred_net_id,
467 	.size = sizeof(struct tc_action_net),
468 };
469 
470 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
471 MODULE_DESCRIPTION("Device Mirror/redirect actions");
472 MODULE_LICENSE("GPL");
473 
474 static int __init mirred_init_module(void)
475 {
476 	int err = register_netdevice_notifier(&mirred_device_notifier);
477 	if (err)
478 		return err;
479 
480 	pr_info("Mirror/redirect action on\n");
481 	return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
482 }
483 
484 static void __exit mirred_cleanup_module(void)
485 {
486 	tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
487 	unregister_netdevice_notifier(&mirred_device_notifier);
488 }
489 
490 module_init(mirred_init_module);
491 module_exit(mirred_cleanup_module);
492