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Linux/net/netfilter/nfnetlink_acct.c

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  1 /*
  2  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
  3  * (C) 2011 Intra2net AG <http://www.intra2net.com>
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation (or any later at your option).
  8  */
  9 #include <linux/init.h>
 10 #include <linux/module.h>
 11 #include <linux/kernel.h>
 12 #include <linux/skbuff.h>
 13 #include <linux/atomic.h>
 14 #include <linux/refcount.h>
 15 #include <linux/netlink.h>
 16 #include <linux/rculist.h>
 17 #include <linux/slab.h>
 18 #include <linux/types.h>
 19 #include <linux/errno.h>
 20 #include <net/netlink.h>
 21 #include <net/sock.h>
 22 
 23 #include <linux/netfilter.h>
 24 #include <linux/netfilter/nfnetlink.h>
 25 #include <linux/netfilter/nfnetlink_acct.h>
 26 
 27 MODULE_LICENSE("GPL");
 28 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 29 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
 30 
 31 struct nf_acct {
 32         atomic64_t              pkts;
 33         atomic64_t              bytes;
 34         unsigned long           flags;
 35         struct list_head        head;
 36         refcount_t              refcnt;
 37         char                    name[NFACCT_NAME_MAX];
 38         struct rcu_head         rcu_head;
 39         char                    data[0];
 40 };
 41 
 42 struct nfacct_filter {
 43         u32 value;
 44         u32 mask;
 45 };
 46 
 47 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
 48 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
 49 
 50 static int nfnl_acct_new(struct net *net, struct sock *nfnl,
 51                          struct sk_buff *skb, const struct nlmsghdr *nlh,
 52                          const struct nlattr * const tb[],
 53                          struct netlink_ext_ack *extack)
 54 {
 55         struct nf_acct *nfacct, *matching = NULL;
 56         char *acct_name;
 57         unsigned int size = 0;
 58         u32 flags = 0;
 59 
 60         if (!tb[NFACCT_NAME])
 61                 return -EINVAL;
 62 
 63         acct_name = nla_data(tb[NFACCT_NAME]);
 64         if (strlen(acct_name) == 0)
 65                 return -EINVAL;
 66 
 67         list_for_each_entry(nfacct, &net->nfnl_acct_list, head) {
 68                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
 69                         continue;
 70 
 71                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 72                         return -EEXIST;
 73 
 74                 matching = nfacct;
 75                 break;
 76         }
 77 
 78         if (matching) {
 79                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
 80                         /* reset counters if you request a replacement. */
 81                         atomic64_set(&matching->pkts, 0);
 82                         atomic64_set(&matching->bytes, 0);
 83                         smp_mb__before_atomic();
 84                         /* reset overquota flag if quota is enabled. */
 85                         if ((matching->flags & NFACCT_F_QUOTA))
 86                                 clear_bit(NFACCT_OVERQUOTA_BIT,
 87                                           &matching->flags);
 88                         return 0;
 89                 }
 90                 return -EBUSY;
 91         }
 92 
 93         if (tb[NFACCT_FLAGS]) {
 94                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
 95                 if (flags & ~NFACCT_F_QUOTA)
 96                         return -EOPNOTSUPP;
 97                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
 98                         return -EINVAL;
 99                 if (flags & NFACCT_F_OVERQUOTA)
100                         return -EINVAL;
101                 if ((flags & NFACCT_F_QUOTA) && !tb[NFACCT_QUOTA])
102                         return -EINVAL;
103 
104                 size += sizeof(u64);
105         }
106 
107         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
108         if (nfacct == NULL)
109                 return -ENOMEM;
110 
111         if (flags & NFACCT_F_QUOTA) {
112                 u64 *quota = (u64 *)nfacct->data;
113 
114                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
115                 nfacct->flags = flags;
116         }
117 
118         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
119 
120         if (tb[NFACCT_BYTES]) {
121                 atomic64_set(&nfacct->bytes,
122                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
123         }
124         if (tb[NFACCT_PKTS]) {
125                 atomic64_set(&nfacct->pkts,
126                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
127         }
128         refcount_set(&nfacct->refcnt, 1);
129         list_add_tail_rcu(&nfacct->head, &net->nfnl_acct_list);
130         return 0;
131 }
132 
133 static int
134 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
135                    int event, struct nf_acct *acct)
136 {
137         struct nlmsghdr *nlh;
138         struct nfgenmsg *nfmsg;
139         unsigned int flags = portid ? NLM_F_MULTI : 0;
140         u64 pkts, bytes;
141         u32 old_flags;
142 
143         event = nfnl_msg_type(NFNL_SUBSYS_ACCT, event);
144         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
145         if (nlh == NULL)
146                 goto nlmsg_failure;
147 
148         nfmsg = nlmsg_data(nlh);
149         nfmsg->nfgen_family = AF_UNSPEC;
150         nfmsg->version = NFNETLINK_V0;
151         nfmsg->res_id = 0;
152 
153         if (nla_put_string(skb, NFACCT_NAME, acct->name))
154                 goto nla_put_failure;
155 
156         old_flags = acct->flags;
157         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
158                 pkts = atomic64_xchg(&acct->pkts, 0);
159                 bytes = atomic64_xchg(&acct->bytes, 0);
160                 smp_mb__before_atomic();
161                 if (acct->flags & NFACCT_F_QUOTA)
162                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
163         } else {
164                 pkts = atomic64_read(&acct->pkts);
165                 bytes = atomic64_read(&acct->bytes);
166         }
167         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts),
168                          NFACCT_PAD) ||
169             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes),
170                          NFACCT_PAD) ||
171             nla_put_be32(skb, NFACCT_USE, htonl(refcount_read(&acct->refcnt))))
172                 goto nla_put_failure;
173         if (acct->flags & NFACCT_F_QUOTA) {
174                 u64 *quota = (u64 *)acct->data;
175 
176                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
177                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota),
178                                  NFACCT_PAD))
179                         goto nla_put_failure;
180         }
181         nlmsg_end(skb, nlh);
182         return skb->len;
183 
184 nlmsg_failure:
185 nla_put_failure:
186         nlmsg_cancel(skb, nlh);
187         return -1;
188 }
189 
190 static int
191 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
192 {
193         struct net *net = sock_net(skb->sk);
194         struct nf_acct *cur, *last;
195         const struct nfacct_filter *filter = cb->data;
196 
197         if (cb->args[2])
198                 return 0;
199 
200         last = (struct nf_acct *)cb->args[1];
201         if (cb->args[1])
202                 cb->args[1] = 0;
203 
204         rcu_read_lock();
205         list_for_each_entry_rcu(cur, &net->nfnl_acct_list, head) {
206                 if (last) {
207                         if (cur != last)
208                                 continue;
209 
210                         last = NULL;
211                 }
212 
213                 if (filter && (cur->flags & filter->mask) != filter->value)
214                         continue;
215 
216                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
217                                        cb->nlh->nlmsg_seq,
218                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
219                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
220                         cb->args[1] = (unsigned long)cur;
221                         break;
222                 }
223         }
224         if (!cb->args[1])
225                 cb->args[2] = 1;
226         rcu_read_unlock();
227         return skb->len;
228 }
229 
230 static int nfnl_acct_done(struct netlink_callback *cb)
231 {
232         kfree(cb->data);
233         return 0;
234 }
235 
236 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
237         [NFACCT_FILTER_MASK]    = { .type = NLA_U32 },
238         [NFACCT_FILTER_VALUE]   = { .type = NLA_U32 },
239 };
240 
241 static struct nfacct_filter *
242 nfacct_filter_alloc(const struct nlattr * const attr)
243 {
244         struct nfacct_filter *filter;
245         struct nlattr *tb[NFACCT_FILTER_MAX + 1];
246         int err;
247 
248         err = nla_parse_nested(tb, NFACCT_FILTER_MAX, attr, filter_policy,
249                                NULL);
250         if (err < 0)
251                 return ERR_PTR(err);
252 
253         if (!tb[NFACCT_FILTER_MASK] || !tb[NFACCT_FILTER_VALUE])
254                 return ERR_PTR(-EINVAL);
255 
256         filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
257         if (!filter)
258                 return ERR_PTR(-ENOMEM);
259 
260         filter->mask = ntohl(nla_get_be32(tb[NFACCT_FILTER_MASK]));
261         filter->value = ntohl(nla_get_be32(tb[NFACCT_FILTER_VALUE]));
262 
263         return filter;
264 }
265 
266 static int nfnl_acct_get(struct net *net, struct sock *nfnl,
267                          struct sk_buff *skb, const struct nlmsghdr *nlh,
268                          const struct nlattr * const tb[],
269                          struct netlink_ext_ack *extack)
270 {
271         int ret = -ENOENT;
272         struct nf_acct *cur;
273         char *acct_name;
274 
275         if (nlh->nlmsg_flags & NLM_F_DUMP) {
276                 struct netlink_dump_control c = {
277                         .dump = nfnl_acct_dump,
278                         .done = nfnl_acct_done,
279                 };
280 
281                 if (tb[NFACCT_FILTER]) {
282                         struct nfacct_filter *filter;
283 
284                         filter = nfacct_filter_alloc(tb[NFACCT_FILTER]);
285                         if (IS_ERR(filter))
286                                 return PTR_ERR(filter);
287 
288                         c.data = filter;
289                 }
290                 return netlink_dump_start(nfnl, skb, nlh, &c);
291         }
292 
293         if (!tb[NFACCT_NAME])
294                 return -EINVAL;
295         acct_name = nla_data(tb[NFACCT_NAME]);
296 
297         list_for_each_entry(cur, &net->nfnl_acct_list, head) {
298                 struct sk_buff *skb2;
299 
300                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
301                         continue;
302 
303                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
304                 if (skb2 == NULL) {
305                         ret = -ENOMEM;
306                         break;
307                 }
308 
309                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
310                                          nlh->nlmsg_seq,
311                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
312                                          NFNL_MSG_ACCT_NEW, cur);
313                 if (ret <= 0) {
314                         kfree_skb(skb2);
315                         break;
316                 }
317                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
318                                         MSG_DONTWAIT);
319                 if (ret > 0)
320                         ret = 0;
321 
322                 /* this avoids a loop in nfnetlink. */
323                 return ret == -EAGAIN ? -ENOBUFS : ret;
324         }
325         return ret;
326 }
327 
328 /* try to delete object, fail if it is still in use. */
329 static int nfnl_acct_try_del(struct nf_acct *cur)
330 {
331         int ret = 0;
332 
333         /* We want to avoid races with nfnl_acct_put. So only when the current
334          * refcnt is 1, we decrease it to 0.
335          */
336         if (refcount_dec_if_one(&cur->refcnt)) {
337                 /* We are protected by nfnl mutex. */
338                 list_del_rcu(&cur->head);
339                 kfree_rcu(cur, rcu_head);
340         } else {
341                 ret = -EBUSY;
342         }
343         return ret;
344 }
345 
346 static int nfnl_acct_del(struct net *net, struct sock *nfnl,
347                          struct sk_buff *skb, const struct nlmsghdr *nlh,
348                          const struct nlattr * const tb[],
349                          struct netlink_ext_ack *extack)
350 {
351         struct nf_acct *cur, *tmp;
352         int ret = -ENOENT;
353         char *acct_name;
354 
355         if (!tb[NFACCT_NAME]) {
356                 list_for_each_entry_safe(cur, tmp, &net->nfnl_acct_list, head)
357                         nfnl_acct_try_del(cur);
358 
359                 return 0;
360         }
361         acct_name = nla_data(tb[NFACCT_NAME]);
362 
363         list_for_each_entry(cur, &net->nfnl_acct_list, head) {
364                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
365                         continue;
366 
367                 ret = nfnl_acct_try_del(cur);
368                 if (ret < 0)
369                         return ret;
370 
371                 break;
372         }
373         return ret;
374 }
375 
376 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
377         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
378         [NFACCT_BYTES] = { .type = NLA_U64 },
379         [NFACCT_PKTS] = { .type = NLA_U64 },
380         [NFACCT_FLAGS] = { .type = NLA_U32 },
381         [NFACCT_QUOTA] = { .type = NLA_U64 },
382         [NFACCT_FILTER] = {.type = NLA_NESTED },
383 };
384 
385 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
386         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
387                                             .attr_count = NFACCT_MAX,
388                                             .policy = nfnl_acct_policy },
389         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
390                                             .attr_count = NFACCT_MAX,
391                                             .policy = nfnl_acct_policy },
392         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
393                                             .attr_count = NFACCT_MAX,
394                                             .policy = nfnl_acct_policy },
395         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
396                                             .attr_count = NFACCT_MAX,
397                                             .policy = nfnl_acct_policy },
398 };
399 
400 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
401         .name                           = "acct",
402         .subsys_id                      = NFNL_SUBSYS_ACCT,
403         .cb_count                       = NFNL_MSG_ACCT_MAX,
404         .cb                             = nfnl_acct_cb,
405 };
406 
407 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
408 
409 struct nf_acct *nfnl_acct_find_get(struct net *net, const char *acct_name)
410 {
411         struct nf_acct *cur, *acct = NULL;
412 
413         rcu_read_lock();
414         list_for_each_entry_rcu(cur, &net->nfnl_acct_list, head) {
415                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
416                         continue;
417 
418                 if (!try_module_get(THIS_MODULE))
419                         goto err;
420 
421                 if (!refcount_inc_not_zero(&cur->refcnt)) {
422                         module_put(THIS_MODULE);
423                         goto err;
424                 }
425 
426                 acct = cur;
427                 break;
428         }
429 err:
430         rcu_read_unlock();
431         return acct;
432 }
433 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
434 
435 void nfnl_acct_put(struct nf_acct *acct)
436 {
437         if (refcount_dec_and_test(&acct->refcnt))
438                 kfree_rcu(acct, rcu_head);
439 
440         module_put(THIS_MODULE);
441 }
442 EXPORT_SYMBOL_GPL(nfnl_acct_put);
443 
444 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
445 {
446         atomic64_inc(&nfacct->pkts);
447         atomic64_add(skb->len, &nfacct->bytes);
448 }
449 EXPORT_SYMBOL_GPL(nfnl_acct_update);
450 
451 static void nfnl_overquota_report(struct net *net, struct nf_acct *nfacct)
452 {
453         int ret;
454         struct sk_buff *skb;
455 
456         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
457         if (skb == NULL)
458                 return;
459 
460         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
461                                   nfacct);
462         if (ret <= 0) {
463                 kfree_skb(skb);
464                 return;
465         }
466         netlink_broadcast(net->nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
467                           GFP_ATOMIC);
468 }
469 
470 int nfnl_acct_overquota(struct net *net, const struct sk_buff *skb,
471                         struct nf_acct *nfacct)
472 {
473         u64 now;
474         u64 *quota;
475         int ret = NFACCT_UNDERQUOTA;
476 
477         /* no place here if we don't have a quota */
478         if (!(nfacct->flags & NFACCT_F_QUOTA))
479                 return NFACCT_NO_QUOTA;
480 
481         quota = (u64 *)nfacct->data;
482         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
483                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
484 
485         ret = now > *quota;
486 
487         if (now >= *quota &&
488             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
489                 nfnl_overquota_report(net, nfacct);
490         }
491 
492         return ret;
493 }
494 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
495 
496 static int __net_init nfnl_acct_net_init(struct net *net)
497 {
498         INIT_LIST_HEAD(&net->nfnl_acct_list);
499 
500         return 0;
501 }
502 
503 static void __net_exit nfnl_acct_net_exit(struct net *net)
504 {
505         struct nf_acct *cur, *tmp;
506 
507         list_for_each_entry_safe(cur, tmp, &net->nfnl_acct_list, head) {
508                 list_del_rcu(&cur->head);
509 
510                 if (refcount_dec_and_test(&cur->refcnt))
511                         kfree_rcu(cur, rcu_head);
512         }
513 }
514 
515 static struct pernet_operations nfnl_acct_ops = {
516         .init   = nfnl_acct_net_init,
517         .exit   = nfnl_acct_net_exit,
518 };
519 
520 static int __init nfnl_acct_init(void)
521 {
522         int ret;
523 
524         ret = register_pernet_subsys(&nfnl_acct_ops);
525         if (ret < 0) {
526                 pr_err("nfnl_acct_init: failed to register pernet ops\n");
527                 goto err_out;
528         }
529 
530         pr_info("nfnl_acct: registering with nfnetlink.\n");
531         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
532         if (ret < 0) {
533                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
534                 goto cleanup_pernet;
535         }
536         return 0;
537 
538 cleanup_pernet:
539         unregister_pernet_subsys(&nfnl_acct_ops);
540 err_out:
541         return ret;
542 }
543 
544 static void __exit nfnl_acct_exit(void)
545 {
546         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
547         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
548         unregister_pernet_subsys(&nfnl_acct_ops);
549 }
550 
551 module_init(nfnl_acct_init);
552 module_exit(nfnl_acct_exit);
553 

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