1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
4  * (C) 2011 Intra2net AG <http://www.intra2net.com>
5  */
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/kernel.h>
9 #include <linux/skbuff.h>
10 #include <linux/atomic.h>
11 #include <linux/refcount.h>
12 #include <linux/netlink.h>
13 #include <linux/rculist.h>
14 #include <linux/slab.h>
15 #include <linux/types.h>
16 #include <linux/errno.h>
17 #include <net/netlink.h>
18 #include <net/sock.h>
19 
20 #include <linux/netfilter.h>
21 #include <linux/netfilter/nfnetlink.h>
22 #include <linux/netfilter/nfnetlink_acct.h>
23 
24 MODULE_LICENSE("GPL");
25 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
26 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
27 
28 struct nf_acct {
29 	atomic64_t		pkts;
30 	atomic64_t		bytes;
31 	unsigned long		flags;
32 	struct list_head	head;
33 	refcount_t		refcnt;
34 	char			name[NFACCT_NAME_MAX];
35 	struct rcu_head		rcu_head;
36 	char			data[0];
37 };
38 
39 struct nfacct_filter {
40 	u32 value;
41 	u32 mask;
42 };
43 
44 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
45 #define NFACCT_OVERQUOTA_BIT	2	/* NFACCT_F_OVERQUOTA */
46 
47 static int nfnl_acct_new(struct net *net, struct sock *nfnl,
48 			 struct sk_buff *skb, const struct nlmsghdr *nlh,
49 			 const struct nlattr * const tb[],
50 			 struct netlink_ext_ack *extack)
51 {
52 	struct nf_acct *nfacct, *matching = NULL;
53 	char *acct_name;
54 	unsigned int size = 0;
55 	u32 flags = 0;
56 
57 	if (!tb[NFACCT_NAME])
58 		return -EINVAL;
59 
60 	acct_name = nla_data(tb[NFACCT_NAME]);
61 	if (strlen(acct_name) == 0)
62 		return -EINVAL;
63 
64 	list_for_each_entry(nfacct, &net->nfnl_acct_list, head) {
65 		if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
66 			continue;
67 
68                 if (nlh->nlmsg_flags & NLM_F_EXCL)
69 			return -EEXIST;
70 
71 		matching = nfacct;
72 		break;
73         }
74 
75 	if (matching) {
76 		if (nlh->nlmsg_flags & NLM_F_REPLACE) {
77 			/* reset counters if you request a replacement. */
78 			atomic64_set(&matching->pkts, 0);
79 			atomic64_set(&matching->bytes, 0);
80 			smp_mb__before_atomic();
81 			/* reset overquota flag if quota is enabled. */
82 			if ((matching->flags & NFACCT_F_QUOTA))
83 				clear_bit(NFACCT_OVERQUOTA_BIT,
84 					  &matching->flags);
85 			return 0;
86 		}
87 		return -EBUSY;
88 	}
89 
90 	if (tb[NFACCT_FLAGS]) {
91 		flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
92 		if (flags & ~NFACCT_F_QUOTA)
93 			return -EOPNOTSUPP;
94 		if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
95 			return -EINVAL;
96 		if (flags & NFACCT_F_OVERQUOTA)
97 			return -EINVAL;
98 		if ((flags & NFACCT_F_QUOTA) && !tb[NFACCT_QUOTA])
99 			return -EINVAL;
100 
101 		size += sizeof(u64);
102 	}
103 
104 	nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
105 	if (nfacct == NULL)
106 		return -ENOMEM;
107 
108 	if (flags & NFACCT_F_QUOTA) {
109 		u64 *quota = (u64 *)nfacct->data;
110 
111 		*quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
112 		nfacct->flags = flags;
113 	}
114 
115 	nla_strlcpy(nfacct->name, tb[NFACCT_NAME], NFACCT_NAME_MAX);
116 
117 	if (tb[NFACCT_BYTES]) {
118 		atomic64_set(&nfacct->bytes,
119 			     be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
120 	}
121 	if (tb[NFACCT_PKTS]) {
122 		atomic64_set(&nfacct->pkts,
123 			     be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
124 	}
125 	refcount_set(&nfacct->refcnt, 1);
126 	list_add_tail_rcu(&nfacct->head, &net->nfnl_acct_list);
127 	return 0;
128 }
129 
130 static int
131 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
132 		   int event, struct nf_acct *acct)
133 {
134 	struct nlmsghdr *nlh;
135 	struct nfgenmsg *nfmsg;
136 	unsigned int flags = portid ? NLM_F_MULTI : 0;
137 	u64 pkts, bytes;
138 	u32 old_flags;
139 
140 	event = nfnl_msg_type(NFNL_SUBSYS_ACCT, event);
141 	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
142 	if (nlh == NULL)
143 		goto nlmsg_failure;
144 
145 	nfmsg = nlmsg_data(nlh);
146 	nfmsg->nfgen_family = AF_UNSPEC;
147 	nfmsg->version = NFNETLINK_V0;
148 	nfmsg->res_id = 0;
149 
150 	if (nla_put_string(skb, NFACCT_NAME, acct->name))
151 		goto nla_put_failure;
152 
153 	old_flags = acct->flags;
154 	if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
155 		pkts = atomic64_xchg(&acct->pkts, 0);
156 		bytes = atomic64_xchg(&acct->bytes, 0);
157 		smp_mb__before_atomic();
158 		if (acct->flags & NFACCT_F_QUOTA)
159 			clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
160 	} else {
161 		pkts = atomic64_read(&acct->pkts);
162 		bytes = atomic64_read(&acct->bytes);
163 	}
164 	if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts),
165 			 NFACCT_PAD) ||
166 	    nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes),
167 			 NFACCT_PAD) ||
168 	    nla_put_be32(skb, NFACCT_USE, htonl(refcount_read(&acct->refcnt))))
169 		goto nla_put_failure;
170 	if (acct->flags & NFACCT_F_QUOTA) {
171 		u64 *quota = (u64 *)acct->data;
172 
173 		if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
174 		    nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota),
175 				 NFACCT_PAD))
176 			goto nla_put_failure;
177 	}
178 	nlmsg_end(skb, nlh);
179 	return skb->len;
180 
181 nlmsg_failure:
182 nla_put_failure:
183 	nlmsg_cancel(skb, nlh);
184 	return -1;
185 }
186 
187 static int
188 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
189 {
190 	struct net *net = sock_net(skb->sk);
191 	struct nf_acct *cur, *last;
192 	const struct nfacct_filter *filter = cb->data;
193 
194 	if (cb->args[2])
195 		return 0;
196 
197 	last = (struct nf_acct *)cb->args[1];
198 	if (cb->args[1])
199 		cb->args[1] = 0;
200 
201 	rcu_read_lock();
202 	list_for_each_entry_rcu(cur, &net->nfnl_acct_list, head) {
203 		if (last) {
204 			if (cur != last)
205 				continue;
206 
207 			last = NULL;
208 		}
209 
210 		if (filter && (cur->flags & filter->mask) != filter->value)
211 			continue;
212 
213 		if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
214 				       cb->nlh->nlmsg_seq,
215 				       NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
216 				       NFNL_MSG_ACCT_NEW, cur) < 0) {
217 			cb->args[1] = (unsigned long)cur;
218 			break;
219 		}
220 	}
221 	if (!cb->args[1])
222 		cb->args[2] = 1;
223 	rcu_read_unlock();
224 	return skb->len;
225 }
226 
227 static int nfnl_acct_done(struct netlink_callback *cb)
228 {
229 	kfree(cb->data);
230 	return 0;
231 }
232 
233 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
234 	[NFACCT_FILTER_MASK]	= { .type = NLA_U32 },
235 	[NFACCT_FILTER_VALUE]	= { .type = NLA_U32 },
236 };
237 
238 static int nfnl_acct_start(struct netlink_callback *cb)
239 {
240 	const struct nlattr *const attr = cb->data;
241 	struct nlattr *tb[NFACCT_FILTER_MAX + 1];
242 	struct nfacct_filter *filter;
243 	int err;
244 
245 	if (!attr)
246 		return 0;
247 
248 	err = nla_parse_nested_deprecated(tb, NFACCT_FILTER_MAX, attr,
249 					  filter_policy, NULL);
250 	if (err < 0)
251 		return err;
252 
253 	if (!tb[NFACCT_FILTER_MASK] || !tb[NFACCT_FILTER_VALUE])
254 		return -EINVAL;
255 
256 	filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
257 	if (!filter)
258 		return -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 	cb->data = filter;
263 
264 	return 0;
265 }
266 
267 static int nfnl_acct_get(struct net *net, struct sock *nfnl,
268 			 struct sk_buff *skb, const struct nlmsghdr *nlh,
269 			 const struct nlattr * const tb[],
270 			 struct netlink_ext_ack *extack)
271 {
272 	int ret = -ENOENT;
273 	struct nf_acct *cur;
274 	char *acct_name;
275 
276 	if (nlh->nlmsg_flags & NLM_F_DUMP) {
277 		struct netlink_dump_control c = {
278 			.dump = nfnl_acct_dump,
279 			.start = nfnl_acct_start,
280 			.done = nfnl_acct_done,
281 			.data = (void *)tb[NFACCT_FILTER],
282 		};
283 
284 		return netlink_dump_start(nfnl, skb, nlh, &c);
285 	}
286 
287 	if (!tb[NFACCT_NAME])
288 		return -EINVAL;
289 	acct_name = nla_data(tb[NFACCT_NAME]);
290 
291 	list_for_each_entry(cur, &net->nfnl_acct_list, head) {
292 		struct sk_buff *skb2;
293 
294 		if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
295 			continue;
296 
297 		skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
298 		if (skb2 == NULL) {
299 			ret = -ENOMEM;
300 			break;
301 		}
302 
303 		ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
304 					 nlh->nlmsg_seq,
305 					 NFNL_MSG_TYPE(nlh->nlmsg_type),
306 					 NFNL_MSG_ACCT_NEW, cur);
307 		if (ret <= 0) {
308 			kfree_skb(skb2);
309 			break;
310 		}
311 		ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
312 					MSG_DONTWAIT);
313 		if (ret > 0)
314 			ret = 0;
315 
316 		/* this avoids a loop in nfnetlink. */
317 		return ret == -EAGAIN ? -ENOBUFS : ret;
318 	}
319 	return ret;
320 }
321 
322 /* try to delete object, fail if it is still in use. */
323 static int nfnl_acct_try_del(struct nf_acct *cur)
324 {
325 	int ret = 0;
326 
327 	/* We want to avoid races with nfnl_acct_put. So only when the current
328 	 * refcnt is 1, we decrease it to 0.
329 	 */
330 	if (refcount_dec_if_one(&cur->refcnt)) {
331 		/* We are protected by nfnl mutex. */
332 		list_del_rcu(&cur->head);
333 		kfree_rcu(cur, rcu_head);
334 	} else {
335 		ret = -EBUSY;
336 	}
337 	return ret;
338 }
339 
340 static int nfnl_acct_del(struct net *net, struct sock *nfnl,
341 			 struct sk_buff *skb, const struct nlmsghdr *nlh,
342 			 const struct nlattr * const tb[],
343 			 struct netlink_ext_ack *extack)
344 {
345 	struct nf_acct *cur, *tmp;
346 	int ret = -ENOENT;
347 	char *acct_name;
348 
349 	if (!tb[NFACCT_NAME]) {
350 		list_for_each_entry_safe(cur, tmp, &net->nfnl_acct_list, head)
351 			nfnl_acct_try_del(cur);
352 
353 		return 0;
354 	}
355 	acct_name = nla_data(tb[NFACCT_NAME]);
356 
357 	list_for_each_entry(cur, &net->nfnl_acct_list, head) {
358 		if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
359 			continue;
360 
361 		ret = nfnl_acct_try_del(cur);
362 		if (ret < 0)
363 			return ret;
364 
365 		break;
366 	}
367 	return ret;
368 }
369 
370 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
371 	[NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
372 	[NFACCT_BYTES] = { .type = NLA_U64 },
373 	[NFACCT_PKTS] = { .type = NLA_U64 },
374 	[NFACCT_FLAGS] = { .type = NLA_U32 },
375 	[NFACCT_QUOTA] = { .type = NLA_U64 },
376 	[NFACCT_FILTER] = {.type = NLA_NESTED },
377 };
378 
379 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
380 	[NFNL_MSG_ACCT_NEW]		= { .call = nfnl_acct_new,
381 					    .attr_count = NFACCT_MAX,
382 					    .policy = nfnl_acct_policy },
383 	[NFNL_MSG_ACCT_GET] 		= { .call = nfnl_acct_get,
384 					    .attr_count = NFACCT_MAX,
385 					    .policy = nfnl_acct_policy },
386 	[NFNL_MSG_ACCT_GET_CTRZERO] 	= { .call = nfnl_acct_get,
387 					    .attr_count = NFACCT_MAX,
388 					    .policy = nfnl_acct_policy },
389 	[NFNL_MSG_ACCT_DEL]		= { .call = nfnl_acct_del,
390 					    .attr_count = NFACCT_MAX,
391 					    .policy = nfnl_acct_policy },
392 };
393 
394 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
395 	.name				= "acct",
396 	.subsys_id			= NFNL_SUBSYS_ACCT,
397 	.cb_count			= NFNL_MSG_ACCT_MAX,
398 	.cb				= nfnl_acct_cb,
399 };
400 
401 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
402 
403 struct nf_acct *nfnl_acct_find_get(struct net *net, const char *acct_name)
404 {
405 	struct nf_acct *cur, *acct = NULL;
406 
407 	rcu_read_lock();
408 	list_for_each_entry_rcu(cur, &net->nfnl_acct_list, head) {
409 		if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
410 			continue;
411 
412 		if (!try_module_get(THIS_MODULE))
413 			goto err;
414 
415 		if (!refcount_inc_not_zero(&cur->refcnt)) {
416 			module_put(THIS_MODULE);
417 			goto err;
418 		}
419 
420 		acct = cur;
421 		break;
422 	}
423 err:
424 	rcu_read_unlock();
425 	return acct;
426 }
427 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
428 
429 void nfnl_acct_put(struct nf_acct *acct)
430 {
431 	if (refcount_dec_and_test(&acct->refcnt))
432 		kfree_rcu(acct, rcu_head);
433 
434 	module_put(THIS_MODULE);
435 }
436 EXPORT_SYMBOL_GPL(nfnl_acct_put);
437 
438 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
439 {
440 	atomic64_inc(&nfacct->pkts);
441 	atomic64_add(skb->len, &nfacct->bytes);
442 }
443 EXPORT_SYMBOL_GPL(nfnl_acct_update);
444 
445 static void nfnl_overquota_report(struct net *net, struct nf_acct *nfacct)
446 {
447 	int ret;
448 	struct sk_buff *skb;
449 
450 	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
451 	if (skb == NULL)
452 		return;
453 
454 	ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
455 				  nfacct);
456 	if (ret <= 0) {
457 		kfree_skb(skb);
458 		return;
459 	}
460 	netlink_broadcast(net->nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
461 			  GFP_ATOMIC);
462 }
463 
464 int nfnl_acct_overquota(struct net *net, struct nf_acct *nfacct)
465 {
466 	u64 now;
467 	u64 *quota;
468 	int ret = NFACCT_UNDERQUOTA;
469 
470 	/* no place here if we don't have a quota */
471 	if (!(nfacct->flags & NFACCT_F_QUOTA))
472 		return NFACCT_NO_QUOTA;
473 
474 	quota = (u64 *)nfacct->data;
475 	now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
476 	       atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
477 
478 	ret = now > *quota;
479 
480 	if (now >= *quota &&
481 	    !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
482 		nfnl_overquota_report(net, nfacct);
483 	}
484 
485 	return ret;
486 }
487 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
488 
489 static int __net_init nfnl_acct_net_init(struct net *net)
490 {
491 	INIT_LIST_HEAD(&net->nfnl_acct_list);
492 
493 	return 0;
494 }
495 
496 static void __net_exit nfnl_acct_net_exit(struct net *net)
497 {
498 	struct nf_acct *cur, *tmp;
499 
500 	list_for_each_entry_safe(cur, tmp, &net->nfnl_acct_list, head) {
501 		list_del_rcu(&cur->head);
502 
503 		if (refcount_dec_and_test(&cur->refcnt))
504 			kfree_rcu(cur, rcu_head);
505 	}
506 }
507 
508 static struct pernet_operations nfnl_acct_ops = {
509         .init   = nfnl_acct_net_init,
510         .exit   = nfnl_acct_net_exit,
511 };
512 
513 static int __init nfnl_acct_init(void)
514 {
515 	int ret;
516 
517 	ret = register_pernet_subsys(&nfnl_acct_ops);
518 	if (ret < 0) {
519 		pr_err("nfnl_acct_init: failed to register pernet ops\n");
520 		goto err_out;
521 	}
522 
523 	ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
524 	if (ret < 0) {
525 		pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
526 		goto cleanup_pernet;
527 	}
528 	return 0;
529 
530 cleanup_pernet:
531 	unregister_pernet_subsys(&nfnl_acct_ops);
532 err_out:
533 	return ret;
534 }
535 
536 static void __exit nfnl_acct_exit(void)
537 {
538 	nfnetlink_subsys_unregister(&nfnl_acct_subsys);
539 	unregister_pernet_subsys(&nfnl_acct_ops);
540 }
541 
542 module_init(nfnl_acct_init);
543 module_exit(nfnl_acct_exit);
544