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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 <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 int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
208 {
209         unsigned char *b = skb_tail_pointer(skb);
210         struct tcf_mirred *m = to_mirred(a);
211         struct tc_mirred opt = {
212                 .index   = m->tcf_index,
213                 .action  = m->tcf_action,
214                 .refcnt  = m->tcf_refcnt - ref,
215                 .bindcnt = m->tcf_bindcnt - bind,
216                 .eaction = m->tcfm_eaction,
217                 .ifindex = m->tcfm_ifindex,
218         };
219         struct tcf_t t;
220 
221         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
222                 goto nla_put_failure;
223 
224         tcf_tm_dump(&t, &m->tcf_tm);
225         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
226                 goto nla_put_failure;
227         return skb->len;
228 
229 nla_put_failure:
230         nlmsg_trim(skb, b);
231         return -1;
232 }
233 
234 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
235                              struct netlink_callback *cb, int type,
236                              const struct tc_action_ops *ops)
237 {
238         struct tc_action_net *tn = net_generic(net, mirred_net_id);
239 
240         return tcf_generic_walker(tn, skb, cb, type, ops);
241 }
242 
243 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
244 {
245         struct tc_action_net *tn = net_generic(net, mirred_net_id);
246 
247         return tcf_hash_search(tn, a, index);
248 }
249 
250 static int mirred_device_event(struct notifier_block *unused,
251                                unsigned long event, void *ptr)
252 {
253         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
254         struct tcf_mirred *m;
255 
256         ASSERT_RTNL();
257         if (event == NETDEV_UNREGISTER) {
258                 spin_lock_bh(&mirred_list_lock);
259                 list_for_each_entry(m, &mirred_list, tcfm_list) {
260                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
261                                 dev_put(dev);
262                                 /* Note : no rcu grace period necessary, as
263                                  * net_device are already rcu protected.
264                                  */
265                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
266                         }
267                 }
268                 spin_unlock_bh(&mirred_list_lock);
269         }
270 
271         return NOTIFY_DONE;
272 }
273 
274 static struct notifier_block mirred_device_notifier = {
275         .notifier_call = mirred_device_event,
276 };
277 
278 static struct tc_action_ops act_mirred_ops = {
279         .kind           =       "mirred",
280         .type           =       TCA_ACT_MIRRED,
281         .owner          =       THIS_MODULE,
282         .act            =       tcf_mirred,
283         .dump           =       tcf_mirred_dump,
284         .cleanup        =       tcf_mirred_release,
285         .init           =       tcf_mirred_init,
286         .walk           =       tcf_mirred_walker,
287         .lookup         =       tcf_mirred_search,
288         .size           =       sizeof(struct tcf_mirred),
289 };
290 
291 static __net_init int mirred_init_net(struct net *net)
292 {
293         struct tc_action_net *tn = net_generic(net, mirred_net_id);
294 
295         return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK);
296 }
297 
298 static void __net_exit mirred_exit_net(struct net *net)
299 {
300         struct tc_action_net *tn = net_generic(net, mirred_net_id);
301 
302         tc_action_net_exit(tn);
303 }
304 
305 static struct pernet_operations mirred_net_ops = {
306         .init = mirred_init_net,
307         .exit = mirred_exit_net,
308         .id   = &mirred_net_id,
309         .size = sizeof(struct tc_action_net),
310 };
311 
312 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
313 MODULE_DESCRIPTION("Device Mirror/redirect actions");
314 MODULE_LICENSE("GPL");
315 
316 static int __init mirred_init_module(void)
317 {
318         int err = register_netdevice_notifier(&mirred_device_notifier);
319         if (err)
320                 return err;
321 
322         pr_info("Mirror/redirect action on\n");
323         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
324 }
325 
326 static void __exit mirred_cleanup_module(void)
327 {
328         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
329         unregister_netdevice_notifier(&mirred_device_notifier);
330 }
331 
332 module_init(mirred_init_module);
333 module_exit(mirred_cleanup_module);
334 

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