1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * (C) 2007 Patrick McHardy <kaber@trash.net>
4 */
5#include <linux/module.h>
6#include <linux/skbuff.h>
7#include <linux/gen_stats.h>
8#include <linux/jhash.h>
9#include <linux/rtnetlink.h>
10#include <linux/random.h>
11#include <linux/slab.h>
12#include <net/gen_stats.h>
13#include <net/netlink.h>
14#include <net/netns/generic.h>
15
16#include <linux/netfilter/x_tables.h>
17#include <linux/netfilter/xt_RATEEST.h>
18#include <net/netfilter/xt_rateest.h>
19
20#define RATEEST_HSIZE	16
21
22struct xt_rateest_net {
23	struct mutex hash_lock;
24	struct hlist_head hash[RATEEST_HSIZE];
25};
26
27static unsigned int xt_rateest_id;
28
29static unsigned int jhash_rnd __read_mostly;
30
31static unsigned int xt_rateest_hash(const char *name)
32{
33	return jhash(name, sizeof_field(struct xt_rateest, name), jhash_rnd) &
34	       (RATEEST_HSIZE - 1);
35}
36
37static void xt_rateest_hash_insert(struct xt_rateest_net *xn,
38				   struct xt_rateest *est)
39{
40	unsigned int h;
41
42	h = xt_rateest_hash(est->name);
43	hlist_add_head(&est->list, &xn->hash[h]);
44}
45
46static struct xt_rateest *__xt_rateest_lookup(struct xt_rateest_net *xn,
47					      const char *name)
48{
49	struct xt_rateest *est;
50	unsigned int h;
51
52	h = xt_rateest_hash(name);
53	hlist_for_each_entry(est, &xn->hash[h], list) {
54		if (strcmp(est->name, name) == 0) {
55			est->refcnt++;
56			return est;
57		}
58	}
59
60	return NULL;
61}
62
63struct xt_rateest *xt_rateest_lookup(struct net *net, const char *name)
64{
65	struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
66	struct xt_rateest *est;
67
68	mutex_lock(&xn->hash_lock);
69	est = __xt_rateest_lookup(xn, name);
70	mutex_unlock(&xn->hash_lock);
71	return est;
72}
73EXPORT_SYMBOL_GPL(xt_rateest_lookup);
74
75void xt_rateest_put(struct net *net, struct xt_rateest *est)
76{
77	struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
78
79	mutex_lock(&xn->hash_lock);
80	if (--est->refcnt == 0) {
81		hlist_del(&est->list);
82		gen_kill_estimator(&est->rate_est);
83		/*
84		 * gen_estimator est_timer() might access est->lock or bstats,
85		 * wait a RCU grace period before freeing 'est'
86		 */
87		kfree_rcu(est, rcu);
88	}
89	mutex_unlock(&xn->hash_lock);
90}
91EXPORT_SYMBOL_GPL(xt_rateest_put);
92
93static unsigned int
94xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
95{
96	const struct xt_rateest_target_info *info = par->targinfo;
97	struct gnet_stats_basic_sync *stats = &info->est->bstats;
98
99	spin_lock_bh(&info->est->lock);
100	u64_stats_add(&stats->bytes, skb->len);
101	u64_stats_inc(&stats->packets);
102	spin_unlock_bh(&info->est->lock);
103
104	return XT_CONTINUE;
105}
106
107static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
108{
109	struct xt_rateest_net *xn = net_generic(par->net, xt_rateest_id);
110	struct xt_rateest_target_info *info = par->targinfo;
111	struct xt_rateest *est;
112	struct {
113		struct nlattr		opt;
114		struct gnet_estimator	est;
115	} cfg;
116	int ret;
117
118	if (strnlen(info->name, sizeof(est->name)) >= sizeof(est->name))
119		return -ENAMETOOLONG;
120
121	net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
122
123	mutex_lock(&xn->hash_lock);
124	est = __xt_rateest_lookup(xn, info->name);
125	if (est) {
126		mutex_unlock(&xn->hash_lock);
127		/*
128		 * If estimator parameters are specified, they must match the
129		 * existing estimator.
130		 */
131		if ((!info->interval && !info->ewma_log) ||
132		    (info->interval != est->params.interval ||
133		     info->ewma_log != est->params.ewma_log)) {
134			xt_rateest_put(par->net, est);
135			return -EINVAL;
136		}
137		info->est = est;
138		return 0;
139	}
140
141	ret = -ENOMEM;
142	est = kzalloc(sizeof(*est), GFP_KERNEL);
143	if (!est)
144		goto err1;
145
146	gnet_stats_basic_sync_init(&est->bstats);
147	strscpy(est->name, info->name, sizeof(est->name));
148	spin_lock_init(&est->lock);
149	est->refcnt		= 1;
150	est->params.interval	= info->interval;
151	est->params.ewma_log	= info->ewma_log;
152
153	cfg.opt.nla_len		= nla_attr_size(sizeof(cfg.est));
154	cfg.opt.nla_type	= TCA_STATS_RATE_EST;
155	cfg.est.interval	= info->interval;
156	cfg.est.ewma_log	= info->ewma_log;
157
158	ret = gen_new_estimator(&est->bstats, NULL, &est->rate_est,
159				&est->lock, NULL, &cfg.opt);
160	if (ret < 0)
161		goto err2;
162
163	info->est = est;
164	xt_rateest_hash_insert(xn, est);
165	mutex_unlock(&xn->hash_lock);
166	return 0;
167
168err2:
169	kfree(est);
170err1:
171	mutex_unlock(&xn->hash_lock);
172	return ret;
173}
174
175static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
176{
177	struct xt_rateest_target_info *info = par->targinfo;
178
179	xt_rateest_put(par->net, info->est);
180}
181
182static struct xt_target xt_rateest_tg_reg __read_mostly = {
183	.name       = "RATEEST",
184	.revision   = 0,
185	.family     = NFPROTO_UNSPEC,
186	.target     = xt_rateest_tg,
187	.checkentry = xt_rateest_tg_checkentry,
188	.destroy    = xt_rateest_tg_destroy,
189	.targetsize = sizeof(struct xt_rateest_target_info),
190	.usersize   = offsetof(struct xt_rateest_target_info, est),
191	.me         = THIS_MODULE,
192};
193
194static __net_init int xt_rateest_net_init(struct net *net)
195{
196	struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
197	int i;
198
199	mutex_init(&xn->hash_lock);
200	for (i = 0; i < ARRAY_SIZE(xn->hash); i++)
201		INIT_HLIST_HEAD(&xn->hash[i]);
202	return 0;
203}
204
205static struct pernet_operations xt_rateest_net_ops = {
206	.init = xt_rateest_net_init,
207	.id   = &xt_rateest_id,
208	.size = sizeof(struct xt_rateest_net),
209};
210
211static int __init xt_rateest_tg_init(void)
212{
213	int err = register_pernet_subsys(&xt_rateest_net_ops);
214
215	if (err)
216		return err;
217	return xt_register_target(&xt_rateest_tg_reg);
218}
219
220static void __exit xt_rateest_tg_fini(void)
221{
222	xt_unregister_target(&xt_rateest_tg_reg);
223	unregister_pernet_subsys(&xt_rateest_net_ops);
224}
225
226
227MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
228MODULE_LICENSE("GPL");
229MODULE_DESCRIPTION("Xtables: packet rate estimator");
230MODULE_ALIAS("ipt_RATEEST");
231MODULE_ALIAS("ip6t_RATEEST");
232module_init(xt_rateest_tg_init);
233module_exit(xt_rateest_tg_fini);
234