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TOMOYO Linux Cross Reference
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/netlink.h>
 15 #include <linux/rculist.h>
 16 #include <linux/slab.h>
 17 #include <linux/types.h>
 18 #include <linux/errno.h>
 19 #include <net/netlink.h>
 20 #include <net/sock.h>
 21 
 22 #include <linux/netfilter.h>
 23 #include <linux/netfilter/nfnetlink.h>
 24 #include <linux/netfilter/nfnetlink_acct.h>
 25 
 26 MODULE_LICENSE("GPL");
 27 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 28 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
 29 
 30 static LIST_HEAD(nfnl_acct_list);
 31 
 32 struct nf_acct {
 33         atomic64_t              pkts;
 34         atomic64_t              bytes;
 35         unsigned long           flags;
 36         struct list_head        head;
 37         atomic_t                refcnt;
 38         char                    name[NFACCT_NAME_MAX];
 39         struct rcu_head         rcu_head;
 40         char                    data[0];
 41 };
 42 
 43 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
 44 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
 45 
 46 static int
 47 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
 48              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 49 {
 50         struct nf_acct *nfacct, *matching = NULL;
 51         char *acct_name;
 52         unsigned int size = 0;
 53         u32 flags = 0;
 54 
 55         if (!tb[NFACCT_NAME])
 56                 return -EINVAL;
 57 
 58         acct_name = nla_data(tb[NFACCT_NAME]);
 59         if (strlen(acct_name) == 0)
 60                 return -EINVAL;
 61 
 62         list_for_each_entry(nfacct, &nfnl_acct_list, head) {
 63                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
 64                         continue;
 65 
 66                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 67                         return -EEXIST;
 68 
 69                 matching = nfacct;
 70                 break;
 71         }
 72 
 73         if (matching) {
 74                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
 75                         /* reset counters if you request a replacement. */
 76                         atomic64_set(&matching->pkts, 0);
 77                         atomic64_set(&matching->bytes, 0);
 78                         smp_mb__before_atomic();
 79                         /* reset overquota flag if quota is enabled. */
 80                         if ((matching->flags & NFACCT_F_QUOTA))
 81                                 clear_bit(NFACCT_OVERQUOTA_BIT,
 82                                           &matching->flags);
 83                         return 0;
 84                 }
 85                 return -EBUSY;
 86         }
 87 
 88         if (tb[NFACCT_FLAGS]) {
 89                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
 90                 if (flags & ~NFACCT_F_QUOTA)
 91                         return -EOPNOTSUPP;
 92                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
 93                         return -EINVAL;
 94                 if (flags & NFACCT_F_OVERQUOTA)
 95                         return -EINVAL;
 96 
 97                 size += sizeof(u64);
 98         }
 99 
100         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
101         if (nfacct == NULL)
102                 return -ENOMEM;
103 
104         if (flags & NFACCT_F_QUOTA) {
105                 u64 *quota = (u64 *)nfacct->data;
106 
107                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
108                 nfacct->flags = flags;
109         }
110 
111         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
112 
113         if (tb[NFACCT_BYTES]) {
114                 atomic64_set(&nfacct->bytes,
115                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
116         }
117         if (tb[NFACCT_PKTS]) {
118                 atomic64_set(&nfacct->pkts,
119                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
120         }
121         atomic_set(&nfacct->refcnt, 1);
122         list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
123         return 0;
124 }
125 
126 static int
127 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
128                    int event, struct nf_acct *acct)
129 {
130         struct nlmsghdr *nlh;
131         struct nfgenmsg *nfmsg;
132         unsigned int flags = portid ? NLM_F_MULTI : 0;
133         u64 pkts, bytes;
134         u32 old_flags;
135 
136         event |= NFNL_SUBSYS_ACCT << 8;
137         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
138         if (nlh == NULL)
139                 goto nlmsg_failure;
140 
141         nfmsg = nlmsg_data(nlh);
142         nfmsg->nfgen_family = AF_UNSPEC;
143         nfmsg->version = NFNETLINK_V0;
144         nfmsg->res_id = 0;
145 
146         if (nla_put_string(skb, NFACCT_NAME, acct->name))
147                 goto nla_put_failure;
148 
149         old_flags = acct->flags;
150         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
151                 pkts = atomic64_xchg(&acct->pkts, 0);
152                 bytes = atomic64_xchg(&acct->bytes, 0);
153                 smp_mb__before_atomic();
154                 if (acct->flags & NFACCT_F_QUOTA)
155                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
156         } else {
157                 pkts = atomic64_read(&acct->pkts);
158                 bytes = atomic64_read(&acct->bytes);
159         }
160         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts)) ||
161             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes)) ||
162             nla_put_be32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt))))
163                 goto nla_put_failure;
164         if (acct->flags & NFACCT_F_QUOTA) {
165                 u64 *quota = (u64 *)acct->data;
166 
167                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
168                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota)))
169                         goto nla_put_failure;
170         }
171         nlmsg_end(skb, nlh);
172         return skb->len;
173 
174 nlmsg_failure:
175 nla_put_failure:
176         nlmsg_cancel(skb, nlh);
177         return -1;
178 }
179 
180 static int
181 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
182 {
183         struct nf_acct *cur, *last;
184 
185         if (cb->args[2])
186                 return 0;
187 
188         last = (struct nf_acct *)cb->args[1];
189         if (cb->args[1])
190                 cb->args[1] = 0;
191 
192         rcu_read_lock();
193         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
194                 if (last) {
195                         if (cur != last)
196                                 continue;
197 
198                         last = NULL;
199                 }
200                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
201                                        cb->nlh->nlmsg_seq,
202                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
203                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
204                         cb->args[1] = (unsigned long)cur;
205                         break;
206                 }
207         }
208         if (!cb->args[1])
209                 cb->args[2] = 1;
210         rcu_read_unlock();
211         return skb->len;
212 }
213 
214 static int
215 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
216              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
217 {
218         int ret = -ENOENT;
219         struct nf_acct *cur;
220         char *acct_name;
221 
222         if (nlh->nlmsg_flags & NLM_F_DUMP) {
223                 struct netlink_dump_control c = {
224                         .dump = nfnl_acct_dump,
225                 };
226                 return netlink_dump_start(nfnl, skb, nlh, &c);
227         }
228 
229         if (!tb[NFACCT_NAME])
230                 return -EINVAL;
231         acct_name = nla_data(tb[NFACCT_NAME]);
232 
233         list_for_each_entry(cur, &nfnl_acct_list, head) {
234                 struct sk_buff *skb2;
235 
236                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
237                         continue;
238 
239                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
240                 if (skb2 == NULL) {
241                         ret = -ENOMEM;
242                         break;
243                 }
244 
245                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
246                                          nlh->nlmsg_seq,
247                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
248                                          NFNL_MSG_ACCT_NEW, cur);
249                 if (ret <= 0) {
250                         kfree_skb(skb2);
251                         break;
252                 }
253                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
254                                         MSG_DONTWAIT);
255                 if (ret > 0)
256                         ret = 0;
257 
258                 /* this avoids a loop in nfnetlink. */
259                 return ret == -EAGAIN ? -ENOBUFS : ret;
260         }
261         return ret;
262 }
263 
264 /* try to delete object, fail if it is still in use. */
265 static int nfnl_acct_try_del(struct nf_acct *cur)
266 {
267         int ret = 0;
268 
269         /* we want to avoid races with nfnl_acct_find_get. */
270         if (atomic_dec_and_test(&cur->refcnt)) {
271                 /* We are protected by nfnl mutex. */
272                 list_del_rcu(&cur->head);
273                 kfree_rcu(cur, rcu_head);
274         } else {
275                 /* still in use, restore reference counter. */
276                 atomic_inc(&cur->refcnt);
277                 ret = -EBUSY;
278         }
279         return ret;
280 }
281 
282 static int
283 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
284              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
285 {
286         char *acct_name;
287         struct nf_acct *cur;
288         int ret = -ENOENT;
289 
290         if (!tb[NFACCT_NAME]) {
291                 list_for_each_entry(cur, &nfnl_acct_list, head)
292                         nfnl_acct_try_del(cur);
293 
294                 return 0;
295         }
296         acct_name = nla_data(tb[NFACCT_NAME]);
297 
298         list_for_each_entry(cur, &nfnl_acct_list, head) {
299                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
300                         continue;
301 
302                 ret = nfnl_acct_try_del(cur);
303                 if (ret < 0)
304                         return ret;
305 
306                 break;
307         }
308         return ret;
309 }
310 
311 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
312         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
313         [NFACCT_BYTES] = { .type = NLA_U64 },
314         [NFACCT_PKTS] = { .type = NLA_U64 },
315         [NFACCT_FLAGS] = { .type = NLA_U32 },
316         [NFACCT_QUOTA] = { .type = NLA_U64 },
317 };
318 
319 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
320         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
321                                             .attr_count = NFACCT_MAX,
322                                             .policy = nfnl_acct_policy },
323         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
324                                             .attr_count = NFACCT_MAX,
325                                             .policy = nfnl_acct_policy },
326         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
327                                             .attr_count = NFACCT_MAX,
328                                             .policy = nfnl_acct_policy },
329         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
330                                             .attr_count = NFACCT_MAX,
331                                             .policy = nfnl_acct_policy },
332 };
333 
334 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
335         .name                           = "acct",
336         .subsys_id                      = NFNL_SUBSYS_ACCT,
337         .cb_count                       = NFNL_MSG_ACCT_MAX,
338         .cb                             = nfnl_acct_cb,
339 };
340 
341 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
342 
343 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
344 {
345         struct nf_acct *cur, *acct = NULL;
346 
347         rcu_read_lock();
348         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
349                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
350                         continue;
351 
352                 if (!try_module_get(THIS_MODULE))
353                         goto err;
354 
355                 if (!atomic_inc_not_zero(&cur->refcnt)) {
356                         module_put(THIS_MODULE);
357                         goto err;
358                 }
359 
360                 acct = cur;
361                 break;
362         }
363 err:
364         rcu_read_unlock();
365         return acct;
366 }
367 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
368 
369 void nfnl_acct_put(struct nf_acct *acct)
370 {
371         atomic_dec(&acct->refcnt);
372         module_put(THIS_MODULE);
373 }
374 EXPORT_SYMBOL_GPL(nfnl_acct_put);
375 
376 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
377 {
378         atomic64_inc(&nfacct->pkts);
379         atomic64_add(skb->len, &nfacct->bytes);
380 }
381 EXPORT_SYMBOL_GPL(nfnl_acct_update);
382 
383 static void nfnl_overquota_report(struct nf_acct *nfacct)
384 {
385         int ret;
386         struct sk_buff *skb;
387 
388         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
389         if (skb == NULL)
390                 return;
391 
392         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
393                                   nfacct);
394         if (ret <= 0) {
395                 kfree_skb(skb);
396                 return;
397         }
398         netlink_broadcast(init_net.nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
399                           GFP_ATOMIC);
400 }
401 
402 int nfnl_acct_overquota(const struct sk_buff *skb, struct nf_acct *nfacct)
403 {
404         u64 now;
405         u64 *quota;
406         int ret = NFACCT_UNDERQUOTA;
407 
408         /* no place here if we don't have a quota */
409         if (!(nfacct->flags & NFACCT_F_QUOTA))
410                 return NFACCT_NO_QUOTA;
411 
412         quota = (u64 *)nfacct->data;
413         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
414                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
415 
416         ret = now > *quota;
417 
418         if (now >= *quota &&
419             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
420                 nfnl_overquota_report(nfacct);
421         }
422 
423         return ret;
424 }
425 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
426 
427 static int __init nfnl_acct_init(void)
428 {
429         int ret;
430 
431         pr_info("nfnl_acct: registering with nfnetlink.\n");
432         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
433         if (ret < 0) {
434                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
435                 goto err_out;
436         }
437         return 0;
438 err_out:
439         return ret;
440 }
441 
442 static void __exit nfnl_acct_exit(void)
443 {
444         struct nf_acct *cur, *tmp;
445 
446         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
447         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
448 
449         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
450                 list_del_rcu(&cur->head);
451                 /* We are sure that our objects have no clients at this point,
452                  * it's safe to release them all without checking refcnt. */
453                 kfree_rcu(cur, rcu_head);
454         }
455 }
456 
457 module_init(nfnl_acct_init);
458 module_exit(nfnl_acct_exit);
459 

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