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act_police.c
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1 /*
2  * net/sched/police.c Input police filter.
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: Alexey Kuznetsov, <[email protected]>
10  * J Hadi Salim (action changes)
11  */
12 
13 #include <linux/module.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/string.h>
17 #include <linux/errno.h>
18 #include <linux/skbuff.h>
19 #include <linux/rtnetlink.h>
20 #include <linux/init.h>
21 #include <linux/slab.h>
22 #include <net/act_api.h>
23 #include <net/netlink.h>
24 
25 #define L2T(p, L) qdisc_l2t((p)->tcfp_R_tab, L)
26 #define L2T_P(p, L) qdisc_l2t((p)->tcfp_P_tab, L)
27 
28 #define POL_TAB_MASK 15
29 static struct tcf_common *tcf_police_ht[POL_TAB_MASK + 1];
30 static u32 police_idx_gen;
31 static DEFINE_RWLOCK(police_lock);
32 
33 static struct tcf_hashinfo police_hash_info = {
34  .htab = tcf_police_ht,
35  .hmask = POL_TAB_MASK,
36  .lock = &police_lock,
37 };
38 
39 /* old policer structure from before tc actions */
40 struct tc_police_compat {
41  u32 index;
42  int action;
43  u32 limit;
44  u32 burst;
45  u32 mtu;
46  struct tc_ratespec rate;
47  struct tc_ratespec peakrate;
48 };
49 
50 /* Each policer is serialized by its individual spinlock */
51 
52 static int tcf_act_police_walker(struct sk_buff *skb, struct netlink_callback *cb,
53  int type, struct tc_action *a)
54 {
55  struct tcf_common *p;
56  int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
57  struct nlattr *nest;
58 
59  read_lock_bh(&police_lock);
60 
61  s_i = cb->args[0];
62 
63  for (i = 0; i < (POL_TAB_MASK + 1); i++) {
64  p = tcf_police_ht[tcf_hash(i, POL_TAB_MASK)];
65 
66  for (; p; p = p->tcfc_next) {
67  index++;
68  if (index < s_i)
69  continue;
70  a->priv = p;
71  a->order = index;
72  nest = nla_nest_start(skb, a->order);
73  if (nest == NULL)
74  goto nla_put_failure;
75  if (type == RTM_DELACTION)
76  err = tcf_action_dump_1(skb, a, 0, 1);
77  else
78  err = tcf_action_dump_1(skb, a, 0, 0);
79  if (err < 0) {
80  index--;
81  nla_nest_cancel(skb, nest);
82  goto done;
83  }
84  nla_nest_end(skb, nest);
85  n_i++;
86  }
87  }
88 done:
89  read_unlock_bh(&police_lock);
90  if (n_i)
91  cb->args[0] += n_i;
92  return n_i;
93 
94 nla_put_failure:
95  nla_nest_cancel(skb, nest);
96  goto done;
97 }
98 
99 static void tcf_police_destroy(struct tcf_police *p)
100 {
101  unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK);
102  struct tcf_common **p1p;
103 
104  for (p1p = &tcf_police_ht[h]; *p1p; p1p = &(*p1p)->tcfc_next) {
105  if (*p1p == &p->common) {
106  write_lock_bh(&police_lock);
107  *p1p = p->tcf_next;
108  write_unlock_bh(&police_lock);
109  gen_kill_estimator(&p->tcf_bstats,
110  &p->tcf_rate_est);
111  if (p->tcfp_R_tab)
112  qdisc_put_rtab(p->tcfp_R_tab);
113  if (p->tcfp_P_tab)
114  qdisc_put_rtab(p->tcfp_P_tab);
115  /*
116  * gen_estimator est_timer() might access p->tcf_lock
117  * or bstats, wait a RCU grace period before freeing p
118  */
119  kfree_rcu(p, tcf_rcu);
120  return;
121  }
122  }
123  WARN_ON(1);
124 }
125 
126 static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
127  [TCA_POLICE_RATE] = { .len = TC_RTAB_SIZE },
128  [TCA_POLICE_PEAKRATE] = { .len = TC_RTAB_SIZE },
129  [TCA_POLICE_AVRATE] = { .type = NLA_U32 },
130  [TCA_POLICE_RESULT] = { .type = NLA_U32 },
131 };
132 
133 static int tcf_act_police_locate(struct nlattr *nla, struct nlattr *est,
134  struct tc_action *a, int ovr, int bind)
135 {
136  unsigned int h;
137  int ret = 0, err;
138  struct nlattr *tb[TCA_POLICE_MAX + 1];
139  struct tc_police *parm;
140  struct tcf_police *police;
141  struct qdisc_rate_table *R_tab = NULL, *P_tab = NULL;
142  int size;
143 
144  if (nla == NULL)
145  return -EINVAL;
146 
147  err = nla_parse_nested(tb, TCA_POLICE_MAX, nla, police_policy);
148  if (err < 0)
149  return err;
150 
151  if (tb[TCA_POLICE_TBF] == NULL)
152  return -EINVAL;
153  size = nla_len(tb[TCA_POLICE_TBF]);
154  if (size != sizeof(*parm) && size != sizeof(struct tc_police_compat))
155  return -EINVAL;
156  parm = nla_data(tb[TCA_POLICE_TBF]);
157 
158  if (parm->index) {
159  struct tcf_common *pc;
160 
161  pc = tcf_hash_lookup(parm->index, &police_hash_info);
162  if (pc != NULL) {
163  a->priv = pc;
164  police = to_police(pc);
165  if (bind) {
166  police->tcf_bindcnt += 1;
167  police->tcf_refcnt += 1;
168  }
169  if (ovr)
170  goto override;
171  return ret;
172  }
173  }
174 
175  police = kzalloc(sizeof(*police), GFP_KERNEL);
176  if (police == NULL)
177  return -ENOMEM;
178  ret = ACT_P_CREATED;
179  police->tcf_refcnt = 1;
180  spin_lock_init(&police->tcf_lock);
181  if (bind)
182  police->tcf_bindcnt = 1;
183 override:
184  if (parm->rate.rate) {
185  err = -ENOMEM;
186  R_tab = qdisc_get_rtab(&parm->rate, tb[TCA_POLICE_RATE]);
187  if (R_tab == NULL)
188  goto failure;
189 
190  if (parm->peakrate.rate) {
191  P_tab = qdisc_get_rtab(&parm->peakrate,
192  tb[TCA_POLICE_PEAKRATE]);
193  if (P_tab == NULL)
194  goto failure;
195  }
196  }
197 
198  spin_lock_bh(&police->tcf_lock);
199  if (est) {
200  err = gen_replace_estimator(&police->tcf_bstats,
201  &police->tcf_rate_est,
202  &police->tcf_lock, est);
203  if (err)
204  goto failure_unlock;
205  } else if (tb[TCA_POLICE_AVRATE] &&
206  (ret == ACT_P_CREATED ||
207  !gen_estimator_active(&police->tcf_bstats,
208  &police->tcf_rate_est))) {
209  err = -EINVAL;
210  goto failure_unlock;
211  }
212 
213  /* No failure allowed after this point */
214  if (R_tab != NULL) {
215  qdisc_put_rtab(police->tcfp_R_tab);
216  police->tcfp_R_tab = R_tab;
217  }
218  if (P_tab != NULL) {
219  qdisc_put_rtab(police->tcfp_P_tab);
220  police->tcfp_P_tab = P_tab;
221  }
222 
223  if (tb[TCA_POLICE_RESULT])
224  police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
225  police->tcfp_toks = police->tcfp_burst = parm->burst;
226  police->tcfp_mtu = parm->mtu;
227  if (police->tcfp_mtu == 0) {
228  police->tcfp_mtu = ~0;
229  if (police->tcfp_R_tab)
230  police->tcfp_mtu = 255<<police->tcfp_R_tab->rate.cell_log;
231  }
232  if (police->tcfp_P_tab)
233  police->tcfp_ptoks = L2T_P(police, police->tcfp_mtu);
234  police->tcf_action = parm->action;
235 
236  if (tb[TCA_POLICE_AVRATE])
237  police->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);
238 
239  spin_unlock_bh(&police->tcf_lock);
240  if (ret != ACT_P_CREATED)
241  return ret;
242 
243  police->tcfp_t_c = psched_get_time();
244  police->tcf_index = parm->index ? parm->index :
245  tcf_hash_new_index(&police_idx_gen, &police_hash_info);
246  h = tcf_hash(police->tcf_index, POL_TAB_MASK);
247  write_lock_bh(&police_lock);
248  police->tcf_next = tcf_police_ht[h];
249  tcf_police_ht[h] = &police->common;
250  write_unlock_bh(&police_lock);
251 
252  a->priv = police;
253  return ret;
254 
255 failure_unlock:
256  spin_unlock_bh(&police->tcf_lock);
257 failure:
258  if (P_tab)
259  qdisc_put_rtab(P_tab);
260  if (R_tab)
261  qdisc_put_rtab(R_tab);
262  if (ret == ACT_P_CREATED)
263  kfree(police);
264  return err;
265 }
266 
267 static int tcf_act_police_cleanup(struct tc_action *a, int bind)
268 {
269  struct tcf_police *p = a->priv;
270  int ret = 0;
271 
272  if (p != NULL) {
273  if (bind)
274  p->tcf_bindcnt--;
275 
276  p->tcf_refcnt--;
277  if (p->tcf_refcnt <= 0 && !p->tcf_bindcnt) {
278  tcf_police_destroy(p);
279  ret = 1;
280  }
281  }
282  return ret;
283 }
284 
285 static int tcf_act_police(struct sk_buff *skb, const struct tc_action *a,
286  struct tcf_result *res)
287 {
288  struct tcf_police *police = a->priv;
289  psched_time_t now;
290  long toks;
291  long ptoks = 0;
292 
293  spin_lock(&police->tcf_lock);
294 
295  bstats_update(&police->tcf_bstats, skb);
296 
297  if (police->tcfp_ewma_rate &&
298  police->tcf_rate_est.bps >= police->tcfp_ewma_rate) {
299  police->tcf_qstats.overlimits++;
300  if (police->tcf_action == TC_ACT_SHOT)
301  police->tcf_qstats.drops++;
302  spin_unlock(&police->tcf_lock);
303  return police->tcf_action;
304  }
305 
306  if (qdisc_pkt_len(skb) <= police->tcfp_mtu) {
307  if (police->tcfp_R_tab == NULL) {
308  spin_unlock(&police->tcf_lock);
309  return police->tcfp_result;
310  }
311 
312  now = psched_get_time();
313  toks = psched_tdiff_bounded(now, police->tcfp_t_c,
314  police->tcfp_burst);
315  if (police->tcfp_P_tab) {
316  ptoks = toks + police->tcfp_ptoks;
317  if (ptoks > (long)L2T_P(police, police->tcfp_mtu))
318  ptoks = (long)L2T_P(police, police->tcfp_mtu);
319  ptoks -= L2T_P(police, qdisc_pkt_len(skb));
320  }
321  toks += police->tcfp_toks;
322  if (toks > (long)police->tcfp_burst)
323  toks = police->tcfp_burst;
324  toks -= L2T(police, qdisc_pkt_len(skb));
325  if ((toks|ptoks) >= 0) {
326  police->tcfp_t_c = now;
327  police->tcfp_toks = toks;
328  police->tcfp_ptoks = ptoks;
329  spin_unlock(&police->tcf_lock);
330  return police->tcfp_result;
331  }
332  }
333 
334  police->tcf_qstats.overlimits++;
335  if (police->tcf_action == TC_ACT_SHOT)
336  police->tcf_qstats.drops++;
337  spin_unlock(&police->tcf_lock);
338  return police->tcf_action;
339 }
340 
341 static int
342 tcf_act_police_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
343 {
344  unsigned char *b = skb_tail_pointer(skb);
345  struct tcf_police *police = a->priv;
346  struct tc_police opt = {
347  .index = police->tcf_index,
348  .action = police->tcf_action,
349  .mtu = police->tcfp_mtu,
350  .burst = police->tcfp_burst,
351  .refcnt = police->tcf_refcnt - ref,
352  .bindcnt = police->tcf_bindcnt - bind,
353  };
354 
355  if (police->tcfp_R_tab)
356  opt.rate = police->tcfp_R_tab->rate;
357  if (police->tcfp_P_tab)
358  opt.peakrate = police->tcfp_P_tab->rate;
359  if (nla_put(skb, TCA_POLICE_TBF, sizeof(opt), &opt))
360  goto nla_put_failure;
361  if (police->tcfp_result &&
362  nla_put_u32(skb, TCA_POLICE_RESULT, police->tcfp_result))
363  goto nla_put_failure;
364  if (police->tcfp_ewma_rate &&
365  nla_put_u32(skb, TCA_POLICE_AVRATE, police->tcfp_ewma_rate))
366  goto nla_put_failure;
367  return skb->len;
368 
369 nla_put_failure:
370  nlmsg_trim(skb, b);
371  return -1;
372 }
373 
374 MODULE_AUTHOR("Alexey Kuznetsov");
375 MODULE_DESCRIPTION("Policing actions");
376 MODULE_LICENSE("GPL");
377 
378 static struct tc_action_ops act_police_ops = {
379  .kind = "police",
380  .hinfo = &police_hash_info,
381  .type = TCA_ID_POLICE,
382  .capab = TCA_CAP_NONE,
383  .owner = THIS_MODULE,
384  .act = tcf_act_police,
385  .dump = tcf_act_police_dump,
386  .cleanup = tcf_act_police_cleanup,
387  .lookup = tcf_hash_search,
388  .init = tcf_act_police_locate,
389  .walk = tcf_act_police_walker
390 };
391 
392 static int __init
393 police_init_module(void)
394 {
395  return tcf_register_action(&act_police_ops);
396 }
397 
398 static void __exit
399 police_cleanup_module(void)
400 {
401  tcf_unregister_action(&act_police_ops);
402 }
403 
404 module_init(police_init_module);
405 module_exit(police_cleanup_module);
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