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 struct list_head head;
36 atomic_t refcnt;
37 char name[NFACCT_NAME_MAX];
38 struct rcu_head rcu_head;
39 };
40
41 static int
nfnl_acct_new(struct sock * nfnl,struct sk_buff * skb,const struct nlmsghdr * nlh,const struct nlattr * const tb[])42 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
43 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
44 {
45 struct nf_acct *nfacct, *matching = NULL;
46 char *acct_name;
47
48 if (!tb[NFACCT_NAME])
49 return -EINVAL;
50
51 acct_name = nla_data(tb[NFACCT_NAME]);
52
53 list_for_each_entry(nfacct, &nfnl_acct_list, head) {
54 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
55 continue;
56
57 if (nlh->nlmsg_flags & NLM_F_EXCL)
58 return -EEXIST;
59
60 matching = nfacct;
61 break;
62 }
63
64 if (matching) {
65 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
66 /* reset counters if you request a replacement. */
67 atomic64_set(&matching->pkts, 0);
68 atomic64_set(&matching->bytes, 0);
69 return 0;
70 }
71 return -EBUSY;
72 }
73
74 nfacct = kzalloc(sizeof(struct nf_acct), GFP_KERNEL);
75 if (nfacct == NULL)
76 return -ENOMEM;
77
78 strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
79
80 if (tb[NFACCT_BYTES]) {
81 atomic64_set(&nfacct->bytes,
82 be64_to_cpu(nla_get_u64(tb[NFACCT_BYTES])));
83 }
84 if (tb[NFACCT_PKTS]) {
85 atomic64_set(&nfacct->pkts,
86 be64_to_cpu(nla_get_u64(tb[NFACCT_PKTS])));
87 }
88 atomic_set(&nfacct->refcnt, 1);
89 list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
90 return 0;
91 }
92
93 static int
nfnl_acct_fill_info(struct sk_buff * skb,u32 pid,u32 seq,u32 type,int event,struct nf_acct * acct)94 nfnl_acct_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
95 int event, struct nf_acct *acct)
96 {
97 struct nlmsghdr *nlh;
98 struct nfgenmsg *nfmsg;
99 unsigned int flags = pid ? NLM_F_MULTI : 0;
100 u64 pkts, bytes;
101
102 event |= NFNL_SUBSYS_ACCT << 8;
103 nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags);
104 if (nlh == NULL)
105 goto nlmsg_failure;
106
107 nfmsg = nlmsg_data(nlh);
108 nfmsg->nfgen_family = AF_UNSPEC;
109 nfmsg->version = NFNETLINK_V0;
110 nfmsg->res_id = 0;
111
112 NLA_PUT_STRING(skb, NFACCT_NAME, acct->name);
113
114 if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
115 pkts = atomic64_xchg(&acct->pkts, 0);
116 bytes = atomic64_xchg(&acct->bytes, 0);
117 } else {
118 pkts = atomic64_read(&acct->pkts);
119 bytes = atomic64_read(&acct->bytes);
120 }
121 NLA_PUT_BE64(skb, NFACCT_PKTS, cpu_to_be64(pkts));
122 NLA_PUT_BE64(skb, NFACCT_BYTES, cpu_to_be64(bytes));
123 NLA_PUT_BE32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt)));
124
125 nlmsg_end(skb, nlh);
126 return skb->len;
127
128 nlmsg_failure:
129 nla_put_failure:
130 nlmsg_cancel(skb, nlh);
131 return -1;
132 }
133
134 static int
nfnl_acct_dump(struct sk_buff * skb,struct netlink_callback * cb)135 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
136 {
137 struct nf_acct *cur, *last;
138
139 if (cb->args[2])
140 return 0;
141
142 last = (struct nf_acct *)cb->args[1];
143 if (cb->args[1])
144 cb->args[1] = 0;
145
146 rcu_read_lock();
147 list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
148 if (last && cur != last)
149 continue;
150
151 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).pid,
152 cb->nlh->nlmsg_seq,
153 NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
154 NFNL_MSG_ACCT_NEW, cur) < 0) {
155 cb->args[1] = (unsigned long)cur;
156 break;
157 }
158 }
159 if (!cb->args[1])
160 cb->args[2] = 1;
161 rcu_read_unlock();
162 return skb->len;
163 }
164
165 static int
nfnl_acct_get(struct sock * nfnl,struct sk_buff * skb,const struct nlmsghdr * nlh,const struct nlattr * const tb[])166 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
167 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
168 {
169 int ret = -ENOENT;
170 struct nf_acct *cur;
171 char *acct_name;
172
173 if (nlh->nlmsg_flags & NLM_F_DUMP) {
174 struct netlink_dump_control c = {
175 .dump = nfnl_acct_dump,
176 };
177 return netlink_dump_start(nfnl, skb, nlh, &c);
178 }
179
180 if (!tb[NFACCT_NAME])
181 return -EINVAL;
182 acct_name = nla_data(tb[NFACCT_NAME]);
183
184 list_for_each_entry(cur, &nfnl_acct_list, head) {
185 struct sk_buff *skb2;
186
187 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
188 continue;
189
190 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
191 if (skb2 == NULL) {
192 ret = -ENOMEM;
193 break;
194 }
195
196 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).pid,
197 nlh->nlmsg_seq,
198 NFNL_MSG_TYPE(nlh->nlmsg_type),
199 NFNL_MSG_ACCT_NEW, cur);
200 if (ret <= 0) {
201 kfree_skb(skb2);
202 break;
203 }
204 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).pid,
205 MSG_DONTWAIT);
206 if (ret > 0)
207 ret = 0;
208
209 /* this avoids a loop in nfnetlink. */
210 return ret == -EAGAIN ? -ENOBUFS : ret;
211 }
212 return ret;
213 }
214
215 /* try to delete object, fail if it is still in use. */
nfnl_acct_try_del(struct nf_acct * cur)216 static int nfnl_acct_try_del(struct nf_acct *cur)
217 {
218 int ret = 0;
219
220 /* we want to avoid races with nfnl_acct_find_get. */
221 if (atomic_dec_and_test(&cur->refcnt)) {
222 /* We are protected by nfnl mutex. */
223 list_del_rcu(&cur->head);
224 kfree_rcu(cur, rcu_head);
225 } else {
226 /* still in use, restore reference counter. */
227 atomic_inc(&cur->refcnt);
228 ret = -EBUSY;
229 }
230 return ret;
231 }
232
233 static int
nfnl_acct_del(struct sock * nfnl,struct sk_buff * skb,const struct nlmsghdr * nlh,const struct nlattr * const tb[])234 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
235 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
236 {
237 char *acct_name;
238 struct nf_acct *cur;
239 int ret = -ENOENT;
240
241 if (!tb[NFACCT_NAME]) {
242 list_for_each_entry(cur, &nfnl_acct_list, head)
243 nfnl_acct_try_del(cur);
244
245 return 0;
246 }
247 acct_name = nla_data(tb[NFACCT_NAME]);
248
249 list_for_each_entry(cur, &nfnl_acct_list, head) {
250 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
251 continue;
252
253 ret = nfnl_acct_try_del(cur);
254 if (ret < 0)
255 return ret;
256
257 break;
258 }
259 return ret;
260 }
261
262 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
263 [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
264 [NFACCT_BYTES] = { .type = NLA_U64 },
265 [NFACCT_PKTS] = { .type = NLA_U64 },
266 };
267
268 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
269 [NFNL_MSG_ACCT_NEW] = { .call = nfnl_acct_new,
270 .attr_count = NFACCT_MAX,
271 .policy = nfnl_acct_policy },
272 [NFNL_MSG_ACCT_GET] = { .call = nfnl_acct_get,
273 .attr_count = NFACCT_MAX,
274 .policy = nfnl_acct_policy },
275 [NFNL_MSG_ACCT_GET_CTRZERO] = { .call = nfnl_acct_get,
276 .attr_count = NFACCT_MAX,
277 .policy = nfnl_acct_policy },
278 [NFNL_MSG_ACCT_DEL] = { .call = nfnl_acct_del,
279 .attr_count = NFACCT_MAX,
280 .policy = nfnl_acct_policy },
281 };
282
283 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
284 .name = "acct",
285 .subsys_id = NFNL_SUBSYS_ACCT,
286 .cb_count = NFNL_MSG_ACCT_MAX,
287 .cb = nfnl_acct_cb,
288 };
289
290 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
291
nfnl_acct_find_get(const char * acct_name)292 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
293 {
294 struct nf_acct *cur, *acct = NULL;
295
296 rcu_read_lock();
297 list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
298 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
299 continue;
300
301 if (!try_module_get(THIS_MODULE))
302 goto err;
303
304 if (!atomic_inc_not_zero(&cur->refcnt)) {
305 module_put(THIS_MODULE);
306 goto err;
307 }
308
309 acct = cur;
310 break;
311 }
312 err:
313 rcu_read_unlock();
314 return acct;
315 }
316 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
317
nfnl_acct_put(struct nf_acct * acct)318 void nfnl_acct_put(struct nf_acct *acct)
319 {
320 atomic_dec(&acct->refcnt);
321 module_put(THIS_MODULE);
322 }
323 EXPORT_SYMBOL_GPL(nfnl_acct_put);
324
nfnl_acct_update(const struct sk_buff * skb,struct nf_acct * nfacct)325 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
326 {
327 atomic64_inc(&nfacct->pkts);
328 atomic64_add(skb->len, &nfacct->bytes);
329 }
330 EXPORT_SYMBOL_GPL(nfnl_acct_update);
331
nfnl_acct_init(void)332 static int __init nfnl_acct_init(void)
333 {
334 int ret;
335
336 pr_info("nfnl_acct: registering with nfnetlink.\n");
337 ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
338 if (ret < 0) {
339 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
340 goto err_out;
341 }
342 return 0;
343 err_out:
344 return ret;
345 }
346
nfnl_acct_exit(void)347 static void __exit nfnl_acct_exit(void)
348 {
349 struct nf_acct *cur, *tmp;
350
351 pr_info("nfnl_acct: unregistering from nfnetlink.\n");
352 nfnetlink_subsys_unregister(&nfnl_acct_subsys);
353
354 list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
355 list_del_rcu(&cur->head);
356 /* We are sure that our objects have no clients at this point,
357 * it's safe to release them all without checking refcnt. */
358 kfree_rcu(cur, rcu_head);
359 }
360 }
361
362 module_init(nfnl_acct_init);
363 module_exit(nfnl_acct_exit);
364