xref: /openbmc/linux/net/sched/act_mirred.c (revision bd336e63)
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 <net/net_namespace.h>
25 #include <net/netlink.h>
26 #include <net/pkt_sched.h>
27 #include <linux/tc_act/tc_mirred.h>
28 #include <net/tc_act/tc_mirred.h>
29 
30 #include <linux/if_arp.h>
31 
32 #define MIRRED_TAB_MASK     7
33 static LIST_HEAD(mirred_list);
34 static DEFINE_SPINLOCK(mirred_list_lock);
35 
36 static void tcf_mirred_release(struct tc_action *a, int bind)
37 {
38 	struct tcf_mirred *m = to_mirred(a);
39 	struct net_device *dev;
40 
41 	/* We could be called either in a RCU callback or with RTNL lock held. */
42 	spin_lock_bh(&mirred_list_lock);
43 	list_del(&m->tcfm_list);
44 	dev = rcu_dereference_protected(m->tcfm_dev, 1);
45 	if (dev)
46 		dev_put(dev);
47 	spin_unlock_bh(&mirred_list_lock);
48 }
49 
50 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
51 	[TCA_MIRRED_PARMS]	= { .len = sizeof(struct tc_mirred) },
52 };
53 
54 static int mirred_net_id;
55 static struct tc_action_ops act_mirred_ops;
56 
57 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
58 			   struct nlattr *est, struct tc_action **a, int ovr,
59 			   int bind)
60 {
61 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
62 	struct nlattr *tb[TCA_MIRRED_MAX + 1];
63 	struct tc_mirred *parm;
64 	struct tcf_mirred *m;
65 	struct net_device *dev;
66 	int ret, ok_push = 0;
67 	bool exists = false;
68 
69 	if (nla == NULL)
70 		return -EINVAL;
71 	ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
72 	if (ret < 0)
73 		return ret;
74 	if (tb[TCA_MIRRED_PARMS] == NULL)
75 		return -EINVAL;
76 	parm = nla_data(tb[TCA_MIRRED_PARMS]);
77 
78 	exists = tcf_hash_check(tn, parm->index, a, bind);
79 	if (exists && bind)
80 		return 0;
81 
82 	switch (parm->eaction) {
83 	case TCA_EGRESS_MIRROR:
84 	case TCA_EGRESS_REDIR:
85 		break;
86 	default:
87 		if (exists)
88 			tcf_hash_release(*a, bind);
89 		return -EINVAL;
90 	}
91 	if (parm->ifindex) {
92 		dev = __dev_get_by_index(net, parm->ifindex);
93 		if (dev == NULL) {
94 			if (exists)
95 				tcf_hash_release(*a, bind);
96 			return -ENODEV;
97 		}
98 		switch (dev->type) {
99 		case ARPHRD_TUNNEL:
100 		case ARPHRD_TUNNEL6:
101 		case ARPHRD_SIT:
102 		case ARPHRD_IPGRE:
103 		case ARPHRD_VOID:
104 		case ARPHRD_NONE:
105 			ok_push = 0;
106 			break;
107 		default:
108 			ok_push = 1;
109 			break;
110 		}
111 	} else {
112 		dev = NULL;
113 	}
114 
115 	if (!exists) {
116 		if (dev == NULL)
117 			return -EINVAL;
118 		ret = tcf_hash_create(tn, parm->index, est, a,
119 				      &act_mirred_ops, bind, true);
120 		if (ret)
121 			return ret;
122 		ret = ACT_P_CREATED;
123 	} else {
124 		tcf_hash_release(*a, bind);
125 		if (!ovr)
126 			return -EEXIST;
127 	}
128 	m = to_mirred(*a);
129 
130 	ASSERT_RTNL();
131 	m->tcf_action = parm->action;
132 	m->tcfm_eaction = parm->eaction;
133 	if (dev != NULL) {
134 		m->tcfm_ifindex = parm->ifindex;
135 		if (ret != ACT_P_CREATED)
136 			dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
137 		dev_hold(dev);
138 		rcu_assign_pointer(m->tcfm_dev, dev);
139 		m->tcfm_ok_push = ok_push;
140 	}
141 
142 	if (ret == ACT_P_CREATED) {
143 		spin_lock_bh(&mirred_list_lock);
144 		list_add(&m->tcfm_list, &mirred_list);
145 		spin_unlock_bh(&mirred_list_lock);
146 		tcf_hash_insert(tn, *a);
147 	}
148 
149 	return ret;
150 }
151 
152 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
153 		      struct tcf_result *res)
154 {
155 	struct tcf_mirred *m = to_mirred(a);
156 	struct net_device *dev;
157 	struct sk_buff *skb2;
158 	int retval, err;
159 	u32 at;
160 
161 	tcf_lastuse_update(&m->tcf_tm);
162 	bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
163 
164 	rcu_read_lock();
165 	retval = READ_ONCE(m->tcf_action);
166 	dev = rcu_dereference(m->tcfm_dev);
167 	if (unlikely(!dev)) {
168 		pr_notice_once("tc mirred: target device is gone\n");
169 		goto out;
170 	}
171 
172 	if (unlikely(!(dev->flags & IFF_UP))) {
173 		net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
174 				       dev->name);
175 		goto out;
176 	}
177 
178 	at = G_TC_AT(skb->tc_verd);
179 	skb2 = skb_clone(skb, GFP_ATOMIC);
180 	if (!skb2)
181 		goto out;
182 
183 	if (!(at & AT_EGRESS)) {
184 		if (m->tcfm_ok_push)
185 			skb_push_rcsum(skb2, skb->mac_len);
186 	}
187 
188 	/* mirror is always swallowed */
189 	if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
190 		skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);
191 
192 	skb2->skb_iif = skb->dev->ifindex;
193 	skb2->dev = dev;
194 	err = dev_queue_xmit(skb2);
195 
196 	if (err) {
197 out:
198 		qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
199 		if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
200 			retval = TC_ACT_SHOT;
201 	}
202 	rcu_read_unlock();
203 
204 	return retval;
205 }
206 
207 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
208 			     u64 lastuse)
209 {
210 	struct tcf_mirred *m = to_mirred(a);
211 	struct tcf_t *tm = &m->tcf_tm;
212 
213 	_bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
214 	tm->lastuse = lastuse;
215 }
216 
217 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
218 			   int ref)
219 {
220 	unsigned char *b = skb_tail_pointer(skb);
221 	struct tcf_mirred *m = to_mirred(a);
222 	struct tc_mirred opt = {
223 		.index   = m->tcf_index,
224 		.action  = m->tcf_action,
225 		.refcnt  = m->tcf_refcnt - ref,
226 		.bindcnt = m->tcf_bindcnt - bind,
227 		.eaction = m->tcfm_eaction,
228 		.ifindex = m->tcfm_ifindex,
229 	};
230 	struct tcf_t t;
231 
232 	if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
233 		goto nla_put_failure;
234 
235 	tcf_tm_dump(&t, &m->tcf_tm);
236 	if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
237 		goto nla_put_failure;
238 	return skb->len;
239 
240 nla_put_failure:
241 	nlmsg_trim(skb, b);
242 	return -1;
243 }
244 
245 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
246 			     struct netlink_callback *cb, int type,
247 			     const struct tc_action_ops *ops)
248 {
249 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
250 
251 	return tcf_generic_walker(tn, skb, cb, type, ops);
252 }
253 
254 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
255 {
256 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
257 
258 	return tcf_hash_search(tn, a, index);
259 }
260 
261 static int mirred_device_event(struct notifier_block *unused,
262 			       unsigned long event, void *ptr)
263 {
264 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
265 	struct tcf_mirred *m;
266 
267 	ASSERT_RTNL();
268 	if (event == NETDEV_UNREGISTER) {
269 		spin_lock_bh(&mirred_list_lock);
270 		list_for_each_entry(m, &mirred_list, tcfm_list) {
271 			if (rcu_access_pointer(m->tcfm_dev) == dev) {
272 				dev_put(dev);
273 				/* Note : no rcu grace period necessary, as
274 				 * net_device are already rcu protected.
275 				 */
276 				RCU_INIT_POINTER(m->tcfm_dev, NULL);
277 			}
278 		}
279 		spin_unlock_bh(&mirred_list_lock);
280 	}
281 
282 	return NOTIFY_DONE;
283 }
284 
285 static struct notifier_block mirred_device_notifier = {
286 	.notifier_call = mirred_device_event,
287 };
288 
289 static struct tc_action_ops act_mirred_ops = {
290 	.kind		=	"mirred",
291 	.type		=	TCA_ACT_MIRRED,
292 	.owner		=	THIS_MODULE,
293 	.act		=	tcf_mirred,
294 	.stats_update	=	tcf_stats_update,
295 	.dump		=	tcf_mirred_dump,
296 	.cleanup	=	tcf_mirred_release,
297 	.init		=	tcf_mirred_init,
298 	.walk		=	tcf_mirred_walker,
299 	.lookup		=	tcf_mirred_search,
300 	.size		=	sizeof(struct tcf_mirred),
301 };
302 
303 static __net_init int mirred_init_net(struct net *net)
304 {
305 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
306 
307 	return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK);
308 }
309 
310 static void __net_exit mirred_exit_net(struct net *net)
311 {
312 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
313 
314 	tc_action_net_exit(tn);
315 }
316 
317 static struct pernet_operations mirred_net_ops = {
318 	.init = mirred_init_net,
319 	.exit = mirred_exit_net,
320 	.id   = &mirred_net_id,
321 	.size = sizeof(struct tc_action_net),
322 };
323 
324 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
325 MODULE_DESCRIPTION("Device Mirror/redirect actions");
326 MODULE_LICENSE("GPL");
327 
328 static int __init mirred_init_module(void)
329 {
330 	int err = register_netdevice_notifier(&mirred_device_notifier);
331 	if (err)
332 		return err;
333 
334 	pr_info("Mirror/redirect action on\n");
335 	return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
336 }
337 
338 static void __exit mirred_cleanup_module(void)
339 {
340 	tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
341 	unregister_netdevice_notifier(&mirred_device_notifier);
342 }
343 
344 module_init(mirred_init_module);
345 module_exit(mirred_cleanup_module);
346