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 struct nfacct_filter {
44 u32 value;
45 u32 mask;
46 };
47
48 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
49 #define NFACCT_OVERQUOTA_BIT 2 /* NFACCT_F_OVERQUOTA */
50
51 static int
nfnl_acct_new(struct sock * nfnl,struct sk_buff * skb,const struct nlmsghdr * nlh,const struct nlattr * const tb[])52 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
53 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
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, &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
102 size += sizeof(u64);
103 }
104
105 nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
106 if (nfacct == NULL)
107 return -ENOMEM;
108
109 if (flags & NFACCT_F_QUOTA) {
110 u64 *quota = (u64 *)nfacct->data;
111
112 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
113 nfacct->flags = flags;
114 }
115
116 strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
117
118 if (tb[NFACCT_BYTES]) {
119 atomic64_set(&nfacct->bytes,
120 be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
121 }
122 if (tb[NFACCT_PKTS]) {
123 atomic64_set(&nfacct->pkts,
124 be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
125 }
126 atomic_set(&nfacct->refcnt, 1);
127 list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
128 return 0;
129 }
130
131 static int
nfnl_acct_fill_info(struct sk_buff * skb,u32 portid,u32 seq,u32 type,int event,struct nf_acct * acct)132 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
133 int event, struct nf_acct *acct)
134 {
135 struct nlmsghdr *nlh;
136 struct nfgenmsg *nfmsg;
137 unsigned int flags = portid ? NLM_F_MULTI : 0;
138 u64 pkts, bytes;
139 u32 old_flags;
140
141 event |= NFNL_SUBSYS_ACCT << 8;
142 nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
143 if (nlh == NULL)
144 goto nlmsg_failure;
145
146 nfmsg = nlmsg_data(nlh);
147 nfmsg->nfgen_family = AF_UNSPEC;
148 nfmsg->version = NFNETLINK_V0;
149 nfmsg->res_id = 0;
150
151 if (nla_put_string(skb, NFACCT_NAME, acct->name))
152 goto nla_put_failure;
153
154 old_flags = acct->flags;
155 if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
156 pkts = atomic64_xchg(&acct->pkts, 0);
157 bytes = atomic64_xchg(&acct->bytes, 0);
158 smp_mb__before_atomic();
159 if (acct->flags & NFACCT_F_QUOTA)
160 clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
161 } else {
162 pkts = atomic64_read(&acct->pkts);
163 bytes = atomic64_read(&acct->bytes);
164 }
165 if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts)) ||
166 nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes)) ||
167 nla_put_be32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt))))
168 goto nla_put_failure;
169 if (acct->flags & NFACCT_F_QUOTA) {
170 u64 *quota = (u64 *)acct->data;
171
172 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
173 nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota)))
174 goto nla_put_failure;
175 }
176 nlmsg_end(skb, nlh);
177 return skb->len;
178
179 nlmsg_failure:
180 nla_put_failure:
181 nlmsg_cancel(skb, nlh);
182 return -1;
183 }
184
185 static int
nfnl_acct_dump(struct sk_buff * skb,struct netlink_callback * cb)186 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
187 {
188 struct nf_acct *cur, *last;
189 const struct nfacct_filter *filter = cb->data;
190
191 if (cb->args[2])
192 return 0;
193
194 last = (struct nf_acct *)cb->args[1];
195 if (cb->args[1])
196 cb->args[1] = 0;
197
198 rcu_read_lock();
199 list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
200 if (last) {
201 if (cur != last)
202 continue;
203
204 last = NULL;
205 }
206
207 if (filter && (cur->flags & filter->mask) != filter->value)
208 continue;
209
210 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
211 cb->nlh->nlmsg_seq,
212 NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
213 NFNL_MSG_ACCT_NEW, cur) < 0) {
214 cb->args[1] = (unsigned long)cur;
215 break;
216 }
217 }
218 if (!cb->args[1])
219 cb->args[2] = 1;
220 rcu_read_unlock();
221 return skb->len;
222 }
223
nfnl_acct_done(struct netlink_callback * cb)224 static int nfnl_acct_done(struct netlink_callback *cb)
225 {
226 kfree(cb->data);
227 return 0;
228 }
229
230 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
231 [NFACCT_FILTER_MASK] = { .type = NLA_U32 },
232 [NFACCT_FILTER_VALUE] = { .type = NLA_U32 },
233 };
234
235 static struct nfacct_filter *
nfacct_filter_alloc(const struct nlattr * const attr)236 nfacct_filter_alloc(const struct nlattr * const attr)
237 {
238 struct nfacct_filter *filter;
239 struct nlattr *tb[NFACCT_FILTER_MAX + 1];
240 int err;
241
242 err = nla_parse_nested(tb, NFACCT_FILTER_MAX, attr, filter_policy);
243 if (err < 0)
244 return ERR_PTR(err);
245
246 filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
247 if (!filter)
248 return ERR_PTR(-ENOMEM);
249
250 filter->mask = ntohl(nla_get_be32(tb[NFACCT_FILTER_MASK]));
251 filter->value = ntohl(nla_get_be32(tb[NFACCT_FILTER_VALUE]));
252
253 return filter;
254 }
255
256 static int
nfnl_acct_get(struct sock * nfnl,struct sk_buff * skb,const struct nlmsghdr * nlh,const struct nlattr * const tb[])257 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
258 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
259 {
260 int ret = -ENOENT;
261 struct nf_acct *cur;
262 char *acct_name;
263
264 if (nlh->nlmsg_flags & NLM_F_DUMP) {
265 struct netlink_dump_control c = {
266 .dump = nfnl_acct_dump,
267 .done = nfnl_acct_done,
268 };
269
270 if (tb[NFACCT_FILTER]) {
271 struct nfacct_filter *filter;
272
273 filter = nfacct_filter_alloc(tb[NFACCT_FILTER]);
274 if (IS_ERR(filter))
275 return PTR_ERR(filter);
276
277 c.data = filter;
278 }
279 return netlink_dump_start(nfnl, skb, nlh, &c);
280 }
281
282 if (!tb[NFACCT_NAME])
283 return -EINVAL;
284 acct_name = nla_data(tb[NFACCT_NAME]);
285
286 list_for_each_entry(cur, &nfnl_acct_list, head) {
287 struct sk_buff *skb2;
288
289 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
290 continue;
291
292 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
293 if (skb2 == NULL) {
294 ret = -ENOMEM;
295 break;
296 }
297
298 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
299 nlh->nlmsg_seq,
300 NFNL_MSG_TYPE(nlh->nlmsg_type),
301 NFNL_MSG_ACCT_NEW, cur);
302 if (ret <= 0) {
303 kfree_skb(skb2);
304 break;
305 }
306 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
307 MSG_DONTWAIT);
308 if (ret > 0)
309 ret = 0;
310
311 /* this avoids a loop in nfnetlink. */
312 return ret == -EAGAIN ? -ENOBUFS : ret;
313 }
314 return ret;
315 }
316
317 /* try to delete object, fail if it is still in use. */
nfnl_acct_try_del(struct nf_acct * cur)318 static int nfnl_acct_try_del(struct nf_acct *cur)
319 {
320 int ret = 0;
321
322 /* we want to avoid races with nfnl_acct_find_get. */
323 if (atomic_dec_and_test(&cur->refcnt)) {
324 /* We are protected by nfnl mutex. */
325 list_del_rcu(&cur->head);
326 kfree_rcu(cur, rcu_head);
327 } else {
328 /* still in use, restore reference counter. */
329 atomic_inc(&cur->refcnt);
330 ret = -EBUSY;
331 }
332 return ret;
333 }
334
335 static int
nfnl_acct_del(struct sock * nfnl,struct sk_buff * skb,const struct nlmsghdr * nlh,const struct nlattr * const tb[])336 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
337 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
338 {
339 char *acct_name;
340 struct nf_acct *cur;
341 int ret = -ENOENT;
342
343 if (!tb[NFACCT_NAME]) {
344 list_for_each_entry(cur, &nfnl_acct_list, head)
345 nfnl_acct_try_del(cur);
346
347 return 0;
348 }
349 acct_name = nla_data(tb[NFACCT_NAME]);
350
351 list_for_each_entry(cur, &nfnl_acct_list, head) {
352 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
353 continue;
354
355 ret = nfnl_acct_try_del(cur);
356 if (ret < 0)
357 return ret;
358
359 break;
360 }
361 return ret;
362 }
363
364 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
365 [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
366 [NFACCT_BYTES] = { .type = NLA_U64 },
367 [NFACCT_PKTS] = { .type = NLA_U64 },
368 [NFACCT_FLAGS] = { .type = NLA_U32 },
369 [NFACCT_QUOTA] = { .type = NLA_U64 },
370 [NFACCT_FILTER] = {.type = NLA_NESTED },
371 };
372
373 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
374 [NFNL_MSG_ACCT_NEW] = { .call = nfnl_acct_new,
375 .attr_count = NFACCT_MAX,
376 .policy = nfnl_acct_policy },
377 [NFNL_MSG_ACCT_GET] = { .call = nfnl_acct_get,
378 .attr_count = NFACCT_MAX,
379 .policy = nfnl_acct_policy },
380 [NFNL_MSG_ACCT_GET_CTRZERO] = { .call = nfnl_acct_get,
381 .attr_count = NFACCT_MAX,
382 .policy = nfnl_acct_policy },
383 [NFNL_MSG_ACCT_DEL] = { .call = nfnl_acct_del,
384 .attr_count = NFACCT_MAX,
385 .policy = nfnl_acct_policy },
386 };
387
388 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
389 .name = "acct",
390 .subsys_id = NFNL_SUBSYS_ACCT,
391 .cb_count = NFNL_MSG_ACCT_MAX,
392 .cb = nfnl_acct_cb,
393 };
394
395 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
396
nfnl_acct_find_get(const char * acct_name)397 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
398 {
399 struct nf_acct *cur, *acct = NULL;
400
401 rcu_read_lock();
402 list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
403 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
404 continue;
405
406 if (!try_module_get(THIS_MODULE))
407 goto err;
408
409 if (!atomic_inc_not_zero(&cur->refcnt)) {
410 module_put(THIS_MODULE);
411 goto err;
412 }
413
414 acct = cur;
415 break;
416 }
417 err:
418 rcu_read_unlock();
419 return acct;
420 }
421 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
422
nfnl_acct_put(struct nf_acct * acct)423 void nfnl_acct_put(struct nf_acct *acct)
424 {
425 atomic_dec(&acct->refcnt);
426 module_put(THIS_MODULE);
427 }
428 EXPORT_SYMBOL_GPL(nfnl_acct_put);
429
nfnl_acct_update(const struct sk_buff * skb,struct nf_acct * nfacct)430 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
431 {
432 atomic64_inc(&nfacct->pkts);
433 atomic64_add(skb->len, &nfacct->bytes);
434 }
435 EXPORT_SYMBOL_GPL(nfnl_acct_update);
436
nfnl_overquota_report(struct nf_acct * nfacct)437 static void nfnl_overquota_report(struct nf_acct *nfacct)
438 {
439 int ret;
440 struct sk_buff *skb;
441
442 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
443 if (skb == NULL)
444 return;
445
446 ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
447 nfacct);
448 if (ret <= 0) {
449 kfree_skb(skb);
450 return;
451 }
452 netlink_broadcast(init_net.nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
453 GFP_ATOMIC);
454 }
455
nfnl_acct_overquota(const struct sk_buff * skb,struct nf_acct * nfacct)456 int nfnl_acct_overquota(const struct sk_buff *skb, struct nf_acct *nfacct)
457 {
458 u64 now;
459 u64 *quota;
460 int ret = NFACCT_UNDERQUOTA;
461
462 /* no place here if we don't have a quota */
463 if (!(nfacct->flags & NFACCT_F_QUOTA))
464 return NFACCT_NO_QUOTA;
465
466 quota = (u64 *)nfacct->data;
467 now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
468 atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
469
470 ret = now > *quota;
471
472 if (now >= *quota &&
473 !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
474 nfnl_overquota_report(nfacct);
475 }
476
477 return ret;
478 }
479 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
480
nfnl_acct_init(void)481 static int __init nfnl_acct_init(void)
482 {
483 int ret;
484
485 pr_info("nfnl_acct: registering with nfnetlink.\n");
486 ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
487 if (ret < 0) {
488 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
489 goto err_out;
490 }
491 return 0;
492 err_out:
493 return ret;
494 }
495
nfnl_acct_exit(void)496 static void __exit nfnl_acct_exit(void)
497 {
498 struct nf_acct *cur, *tmp;
499
500 pr_info("nfnl_acct: unregistering from nfnetlink.\n");
501 nfnetlink_subsys_unregister(&nfnl_acct_subsys);
502
503 list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
504 list_del_rcu(&cur->head);
505 /* We are sure that our objects have no clients at this point,
506 * it's safe to release them all without checking refcnt. */
507 kfree_rcu(cur, rcu_head);
508 }
509 }
510
511 module_init(nfnl_acct_init);
512 module_exit(nfnl_acct_exit);
513