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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 <linux/if_arp.h>
25 #include <net/net_namespace.h>
26 #include <net/netlink.h>
27 #include <net/pkt_sched.h>
28 #include <linux/tc_act/tc_mirred.h>
29 #include <net/tc_act/tc_mirred.h>
30
31 #define MIRRED_TAB_MASK 7
32 static LIST_HEAD(mirred_list);
33 static DEFINE_SPINLOCK(mirred_list_lock);
34
35 static bool tcf_mirred_is_act_redirect(int action)
36 {
37 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
38 }
39
40 static bool tcf_mirred_act_wants_ingress(int action)
41 {
42 switch (action) {
43 case TCA_EGRESS_REDIR:
44 case TCA_EGRESS_MIRROR:
45 return false;
46 case TCA_INGRESS_REDIR:
47 case TCA_INGRESS_MIRROR:
48 return true;
49 default:
50 BUG();
51 }
52 }
53
54 static void tcf_mirred_release(struct tc_action *a, int bind)
55 {
56 struct tcf_mirred *m = to_mirred(a);
57 struct net_device *dev;
58
59 /* We could be called either in a RCU callback or with RTNL lock held. */
60 spin_lock_bh(&mirred_list_lock);
61 list_del(&m->tcfm_list);
62 dev = rcu_dereference_protected(m->tcfm_dev, 1);
63 if (dev)
64 dev_put(dev);
65 spin_unlock_bh(&mirred_list_lock);
66 }
67
68 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
69 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) },
70 };
71
72 static unsigned int mirred_net_id;
73 static struct tc_action_ops act_mirred_ops;
74
75 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
76 struct nlattr *est, struct tc_action **a, int ovr,
77 int bind)
78 {
79 struct tc_action_net *tn = net_generic(net, mirred_net_id);
80 struct nlattr *tb[TCA_MIRRED_MAX + 1];
81 bool mac_header_xmit = false;
82 struct tc_mirred *parm;
83 struct tcf_mirred *m;
84 struct net_device *dev;
85 bool exists = false;
86 int ret;
87
88 if (nla == NULL)
89 return -EINVAL;
90 ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL);
91 if (ret < 0)
92 return ret;
93 if (tb[TCA_MIRRED_PARMS] == NULL)
94 return -EINVAL;
95 parm = nla_data(tb[TCA_MIRRED_PARMS]);
96
97 exists = tcf_hash_check(tn, parm->index, a, bind);
98 if (exists && bind)
99 return 0;
100
101 switch (parm->eaction) {
102 case TCA_EGRESS_MIRROR:
103 case TCA_EGRESS_REDIR:
104 case TCA_INGRESS_REDIR:
105 case TCA_INGRESS_MIRROR:
106 break;
107 default:
108 if (exists)
109 tcf_hash_release(*a, bind);
110 return -EINVAL;
111 }
112 if (parm->ifindex) {
113 dev = __dev_get_by_index(net, parm->ifindex);
114 if (dev == NULL) {
115 if (exists)
116 tcf_hash_release(*a, bind);
117 return -ENODEV;
118 }
119 mac_header_xmit = dev_is_mac_header_xmit(dev);
120 } else {
121 dev = NULL;
122 }
123
124 if (!exists) {
125 if (dev == NULL)
126 return -EINVAL;
127 ret = tcf_hash_create(tn, parm->index, est, a,
128 &act_mirred_ops, bind, true);
129 if (ret)
130 return ret;
131 ret = ACT_P_CREATED;
132 } else {
133 tcf_hash_release(*a, bind);
134 if (!ovr)
135 return -EEXIST;
136 }
137 m = to_mirred(*a);
138
139 ASSERT_RTNL();
140 m->tcf_action = parm->action;
141 m->tcfm_eaction = parm->eaction;
142 if (dev != NULL) {
143 m->tcfm_ifindex = parm->ifindex;
144 if (ret != ACT_P_CREATED)
145 dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
146 dev_hold(dev);
147 rcu_assign_pointer(m->tcfm_dev, dev);
148 m->tcfm_mac_header_xmit = mac_header_xmit;
149 }
150
151 if (ret == ACT_P_CREATED) {
152 spin_lock_bh(&mirred_list_lock);
153 list_add(&m->tcfm_list, &mirred_list);
154 spin_unlock_bh(&mirred_list_lock);
155 tcf_hash_insert(tn, *a);
156 }
157
158 return ret;
159 }
160
161 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
162 struct tcf_result *res)
163 {
164 struct tcf_mirred *m = to_mirred(a);
165 bool m_mac_header_xmit;
166 struct net_device *dev;
167 struct sk_buff *skb2;
168 int retval, err = 0;
169 int m_eaction;
170 int mac_len;
171
172 tcf_lastuse_update(&m->tcf_tm);
173 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
174
175 rcu_read_lock();
176 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
177 m_eaction = READ_ONCE(m->tcfm_eaction);
178 retval = READ_ONCE(m->tcf_action);
179 dev = rcu_dereference(m->tcfm_dev);
180 if (unlikely(!dev)) {
181 pr_notice_once("tc mirred: target device is gone\n");
182 goto out;
183 }
184
185 if (unlikely(!(dev->flags & IFF_UP))) {
186 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
187 dev->name);
188 goto out;
189 }
190
191 skb2 = skb_clone(skb, GFP_ATOMIC);
192 if (!skb2)
193 goto out;
194
195 /* If action's target direction differs than filter's direction,
196 * and devices expect a mac header on xmit, then mac push/pull is
197 * needed.
198 */
199 if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) &&
200 m_mac_header_xmit) {
201 if (!skb_at_tc_ingress(skb)) {
202 /* caught at egress, act ingress: pull mac */
203 mac_len = skb_network_header(skb) - skb_mac_header(skb);
204 skb_pull_rcsum(skb2, mac_len);
205 } else {
206 /* caught at ingress, act egress: push mac */
207 skb_push_rcsum(skb2, skb->mac_len);
208 }
209 }
210
211 /* mirror is always swallowed */
212 if (tcf_mirred_is_act_redirect(m_eaction)) {
213 skb2->tc_redirected = 1;
214 skb2->tc_from_ingress = skb2->tc_at_ingress;
215 }
216
217 skb2->skb_iif = skb->dev->ifindex;
218 skb2->dev = dev;
219 if (!tcf_mirred_act_wants_ingress(m_eaction))
220 err = dev_queue_xmit(skb2);
221 else
222 err = netif_receive_skb(skb2);
223
224 if (err) {
225 out:
226 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
227 if (tcf_mirred_is_act_redirect(m_eaction))
228 retval = TC_ACT_SHOT;
229 }
230 rcu_read_unlock();
231
232 return retval;
233 }
234
235 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
236 u64 lastuse)
237 {
238 struct tcf_mirred *m = to_mirred(a);
239 struct tcf_t *tm = &m->tcf_tm;
240
241 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
242 tm->lastuse = lastuse;
243 }
244
245 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
246 int ref)
247 {
248 unsigned char *b = skb_tail_pointer(skb);
249 struct tcf_mirred *m = to_mirred(a);
250 struct tc_mirred opt = {
251 .index = m->tcf_index,
252 .action = m->tcf_action,
253 .refcnt = m->tcf_refcnt - ref,
254 .bindcnt = m->tcf_bindcnt - bind,
255 .eaction = m->tcfm_eaction,
256 .ifindex = m->tcfm_ifindex,
257 };
258 struct tcf_t t;
259
260 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
261 goto nla_put_failure;
262
263 tcf_tm_dump(&t, &m->tcf_tm);
264 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
265 goto nla_put_failure;
266 return skb->len;
267
268 nla_put_failure:
269 nlmsg_trim(skb, b);
270 return -1;
271 }
272
273 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
274 struct netlink_callback *cb, int type,
275 const struct tc_action_ops *ops)
276 {
277 struct tc_action_net *tn = net_generic(net, mirred_net_id);
278
279 return tcf_generic_walker(tn, skb, cb, type, ops);
280 }
281
282 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
283 {
284 struct tc_action_net *tn = net_generic(net, mirred_net_id);
285
286 return tcf_hash_search(tn, a, index);
287 }
288
289 static int mirred_device_event(struct notifier_block *unused,
290 unsigned long event, void *ptr)
291 {
292 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
293 struct tcf_mirred *m;
294
295 ASSERT_RTNL();
296 if (event == NETDEV_UNREGISTER) {
297 spin_lock_bh(&mirred_list_lock);
298 list_for_each_entry(m, &mirred_list, tcfm_list) {
299 if (rcu_access_pointer(m->tcfm_dev) == dev) {
300 dev_put(dev);
301 /* Note : no rcu grace period necessary, as
302 * net_device are already rcu protected.
303 */
304 RCU_INIT_POINTER(m->tcfm_dev, NULL);
305 }
306 }
307 spin_unlock_bh(&mirred_list_lock);
308 }
309
310 return NOTIFY_DONE;
311 }
312
313 static struct notifier_block mirred_device_notifier = {
314 .notifier_call = mirred_device_event,
315 };
316
317 static int tcf_mirred_device(const struct tc_action *a, struct net *net,
318 struct net_device **mirred_dev)
319 {
320 int ifindex = tcf_mirred_ifindex(a);
321
322 *mirred_dev = __dev_get_by_index(net, ifindex);
323 if (!*mirred_dev)
324 return -EINVAL;
325 return 0;
326 }
327
328 static struct tc_action_ops act_mirred_ops = {
329 .kind = "mirred",
330 .type = TCA_ACT_MIRRED,
331 .owner = THIS_MODULE,
332 .act = tcf_mirred,
333 .stats_update = tcf_stats_update,
334 .dump = tcf_mirred_dump,
335 .cleanup = tcf_mirred_release,
336 .init = tcf_mirred_init,
337 .walk = tcf_mirred_walker,
338 .lookup = tcf_mirred_search,
339 .size = sizeof(struct tcf_mirred),
340 .get_dev = tcf_mirred_device,
341 };
342
343 static __net_init int mirred_init_net(struct net *net)
344 {
345 struct tc_action_net *tn = net_generic(net, mirred_net_id);
346
347 return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK);
348 }
349
350 static void __net_exit mirred_exit_net(struct net *net)
351 {
352 struct tc_action_net *tn = net_generic(net, mirred_net_id);
353
354 tc_action_net_exit(tn);
355 }
356
357 static struct pernet_operations mirred_net_ops = {
358 .init = mirred_init_net,
359 .exit = mirred_exit_net,
360 .id = &mirred_net_id,
361 .size = sizeof(struct tc_action_net),
362 };
363
364 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
365 MODULE_DESCRIPTION("Device Mirror/redirect actions");
366 MODULE_LICENSE("GPL");
367
368 static int __init mirred_init_module(void)
369 {
370 int err = register_netdevice_notifier(&mirred_device_notifier);
371 if (err)
372 return err;
373
374 pr_info("Mirror/redirect action on\n");
375 return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
376 }
377
378 static void __exit mirred_cleanup_module(void)
379 {
380 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
381 unregister_netdevice_notifier(&mirred_device_notifier);
382 }
383
384 module_init(mirred_init_module);
385 module_exit(mirred_cleanup_module);