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Linux/net/sched/act_mirred.c

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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 static LIST_HEAD(mirred_list);
 32 static DEFINE_SPINLOCK(mirred_list_lock);
 33 
 34 static bool tcf_mirred_is_act_redirect(int action)
 35 {
 36         return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
 37 }
 38 
 39 static bool tcf_mirred_act_wants_ingress(int action)
 40 {
 41         switch (action) {
 42         case TCA_EGRESS_REDIR:
 43         case TCA_EGRESS_MIRROR:
 44                 return false;
 45         case TCA_INGRESS_REDIR:
 46         case TCA_INGRESS_MIRROR:
 47                 return true;
 48         default:
 49                 BUG();
 50         }
 51 }
 52 
 53 static void tcf_mirred_release(struct tc_action *a, int bind)
 54 {
 55         struct tcf_mirred *m = to_mirred(a);
 56         struct net_device *dev;
 57 
 58         /* We could be called either in a RCU callback or with RTNL lock held. */
 59         spin_lock_bh(&mirred_list_lock);
 60         list_del(&m->tcfm_list);
 61         dev = rcu_dereference_protected(m->tcfm_dev, 1);
 62         if (dev)
 63                 dev_put(dev);
 64         spin_unlock_bh(&mirred_list_lock);
 65 }
 66 
 67 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
 68         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
 69 };
 70 
 71 static unsigned int mirred_net_id;
 72 static struct tc_action_ops act_mirred_ops;
 73 
 74 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 75                            struct nlattr *est, struct tc_action **a, int ovr,
 76                            int bind)
 77 {
 78         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 79         struct nlattr *tb[TCA_MIRRED_MAX + 1];
 80         bool mac_header_xmit = false;
 81         struct tc_mirred *parm;
 82         struct tcf_mirred *m;
 83         struct net_device *dev;
 84         bool exists = false;
 85         int ret;
 86 
 87         if (nla == NULL)
 88                 return -EINVAL;
 89         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL);
 90         if (ret < 0)
 91                 return ret;
 92         if (tb[TCA_MIRRED_PARMS] == NULL)
 93                 return -EINVAL;
 94         parm = nla_data(tb[TCA_MIRRED_PARMS]);
 95 
 96         exists = tcf_idr_check(tn, parm->index, a, bind);
 97         if (exists && bind)
 98                 return 0;
 99 
100         switch (parm->eaction) {
101         case TCA_EGRESS_MIRROR:
102         case TCA_EGRESS_REDIR:
103         case TCA_INGRESS_REDIR:
104         case TCA_INGRESS_MIRROR:
105                 break;
106         default:
107                 if (exists)
108                         tcf_idr_release(*a, bind);
109                 return -EINVAL;
110         }
111         if (parm->ifindex) {
112                 dev = __dev_get_by_index(net, parm->ifindex);
113                 if (dev == NULL) {
114                         if (exists)
115                                 tcf_idr_release(*a, bind);
116                         return -ENODEV;
117                 }
118                 mac_header_xmit = dev_is_mac_header_xmit(dev);
119         } else {
120                 dev = NULL;
121         }
122 
123         if (!exists) {
124                 if (dev == NULL)
125                         return -EINVAL;
126                 ret = tcf_idr_create(tn, parm->index, est, a,
127                                      &act_mirred_ops, bind, true);
128                 if (ret)
129                         return ret;
130                 ret = ACT_P_CREATED;
131         } else {
132                 tcf_idr_release(*a, bind);
133                 if (!ovr)
134                         return -EEXIST;
135         }
136         m = to_mirred(*a);
137 
138         ASSERT_RTNL();
139         m->tcf_action = parm->action;
140         m->tcfm_eaction = parm->eaction;
141         if (dev != NULL) {
142                 m->tcfm_ifindex = parm->ifindex;
143                 m->net = net;
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_idr_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 = max_t(u64, 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_idr_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 struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
318 {
319         struct tcf_mirred *m = to_mirred(a);
320 
321         return __dev_get_by_index(m->net, m->tcfm_ifindex);
322 }
323 
324 static struct tc_action_ops act_mirred_ops = {
325         .kind           =       "mirred",
326         .type           =       TCA_ACT_MIRRED,
327         .owner          =       THIS_MODULE,
328         .act            =       tcf_mirred,
329         .stats_update   =       tcf_stats_update,
330         .dump           =       tcf_mirred_dump,
331         .cleanup        =       tcf_mirred_release,
332         .init           =       tcf_mirred_init,
333         .walk           =       tcf_mirred_walker,
334         .lookup         =       tcf_mirred_search,
335         .size           =       sizeof(struct tcf_mirred),
336         .get_dev        =       tcf_mirred_get_dev,
337 };
338 
339 static __net_init int mirred_init_net(struct net *net)
340 {
341         struct tc_action_net *tn = net_generic(net, mirred_net_id);
342 
343         return tc_action_net_init(tn, &act_mirred_ops);
344 }
345 
346 static void __net_exit mirred_exit_net(struct net *net)
347 {
348         struct tc_action_net *tn = net_generic(net, mirred_net_id);
349 
350         tc_action_net_exit(tn);
351 }
352 
353 static struct pernet_operations mirred_net_ops = {
354         .init = mirred_init_net,
355         .exit = mirred_exit_net,
356         .id   = &mirred_net_id,
357         .size = sizeof(struct tc_action_net),
358 };
359 
360 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
361 MODULE_DESCRIPTION("Device Mirror/redirect actions");
362 MODULE_LICENSE("GPL");
363 
364 static int __init mirred_init_module(void)
365 {
366         int err = register_netdevice_notifier(&mirred_device_notifier);
367         if (err)
368                 return err;
369 
370         pr_info("Mirror/redirect action on\n");
371         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
372 }
373 
374 static void __exit mirred_cleanup_module(void)
375 {
376         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
377         unregister_netdevice_notifier(&mirred_device_notifier);
378 }
379 
380 module_init(mirred_init_module);
381 module_exit(mirred_cleanup_module);
382 

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