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1 | /* |
2 | * (C) 2007 Patrick McHardy <kaber@trash.net> |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify |
5 | * it under the terms of the GNU General Public License version 2 as |
6 | * published by the Free Software Foundation. |
7 | */ |
8 | #include <linux/module.h> |
9 | #include <linux/skbuff.h> |
10 | #include <linux/gen_stats.h> |
11 | #include <linux/jhash.h> |
12 | #include <linux/rtnetlink.h> |
13 | #include <linux/random.h> |
14 | #include <linux/slab.h> |
15 | #include <net/gen_stats.h> |
16 | #include <net/netlink.h> |
17 | |
18 | #include <linux/netfilter/x_tables.h> |
19 | #include <linux/netfilter/xt_RATEEST.h> |
20 | #include <net/netfilter/xt_rateest.h> |
21 | |
22 | static DEFINE_MUTEX(xt_rateest_mutex); |
23 | |
24 | #define RATEEST_HSIZE 16 |
25 | static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly; |
26 | static unsigned int jhash_rnd __read_mostly; |
27 | static bool rnd_inited __read_mostly; |
28 | |
29 | static unsigned int xt_rateest_hash(const char *name) |
30 | { |
31 | return jhash(name, FIELD_SIZEOF(struct xt_rateest, name), jhash_rnd) & |
32 | (RATEEST_HSIZE - 1); |
33 | } |
34 | |
35 | static void xt_rateest_hash_insert(struct xt_rateest *est) |
36 | { |
37 | unsigned int h; |
38 | |
39 | h = xt_rateest_hash(est->name); |
40 | hlist_add_head(&est->list, &rateest_hash[h]); |
41 | } |
42 | |
43 | struct xt_rateest *xt_rateest_lookup(const char *name) |
44 | { |
45 | struct xt_rateest *est; |
46 | unsigned int h; |
47 | |
48 | h = xt_rateest_hash(name); |
49 | mutex_lock(&xt_rateest_mutex); |
50 | hlist_for_each_entry(est, &rateest_hash[h], list) { |
51 | if (strcmp(est->name, name) == 0) { |
52 | est->refcnt++; |
53 | mutex_unlock(&xt_rateest_mutex); |
54 | return est; |
55 | } |
56 | } |
57 | mutex_unlock(&xt_rateest_mutex); |
58 | return NULL; |
59 | } |
60 | EXPORT_SYMBOL_GPL(xt_rateest_lookup); |
61 | |
62 | void xt_rateest_put(struct xt_rateest *est) |
63 | { |
64 | mutex_lock(&xt_rateest_mutex); |
65 | if (--est->refcnt == 0) { |
66 | hlist_del(&est->list); |
67 | gen_kill_estimator(&est->bstats, &est->rstats); |
68 | /* |
69 | * gen_estimator est_timer() might access est->lock or bstats, |
70 | * wait a RCU grace period before freeing 'est' |
71 | */ |
72 | kfree_rcu(est, rcu); |
73 | } |
74 | mutex_unlock(&xt_rateest_mutex); |
75 | } |
76 | EXPORT_SYMBOL_GPL(xt_rateest_put); |
77 | |
78 | static unsigned int |
79 | xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par) |
80 | { |
81 | const struct xt_rateest_target_info *info = par->targinfo; |
82 | struct gnet_stats_basic_packed *stats = &info->est->bstats; |
83 | |
84 | spin_lock_bh(&info->est->lock); |
85 | stats->bytes += skb->len; |
86 | stats->packets++; |
87 | spin_unlock_bh(&info->est->lock); |
88 | |
89 | return XT_CONTINUE; |
90 | } |
91 | |
92 | static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par) |
93 | { |
94 | struct xt_rateest_target_info *info = par->targinfo; |
95 | struct xt_rateest *est; |
96 | struct { |
97 | struct nlattr opt; |
98 | struct gnet_estimator est; |
99 | } cfg; |
100 | int ret; |
101 | |
102 | if (unlikely(!rnd_inited)) { |
103 | get_random_bytes(&jhash_rnd, sizeof(jhash_rnd)); |
104 | rnd_inited = true; |
105 | } |
106 | |
107 | est = xt_rateest_lookup(info->name); |
108 | if (est) { |
109 | /* |
110 | * If estimator parameters are specified, they must match the |
111 | * existing estimator. |
112 | */ |
113 | if ((!info->interval && !info->ewma_log) || |
114 | (info->interval != est->params.interval || |
115 | info->ewma_log != est->params.ewma_log)) { |
116 | xt_rateest_put(est); |
117 | return -EINVAL; |
118 | } |
119 | info->est = est; |
120 | return 0; |
121 | } |
122 | |
123 | ret = -ENOMEM; |
124 | est = kzalloc(sizeof(*est), GFP_KERNEL); |
125 | if (!est) |
126 | goto err1; |
127 | |
128 | strlcpy(est->name, info->name, sizeof(est->name)); |
129 | spin_lock_init(&est->lock); |
130 | est->refcnt = 1; |
131 | est->params.interval = info->interval; |
132 | est->params.ewma_log = info->ewma_log; |
133 | |
134 | cfg.opt.nla_len = nla_attr_size(sizeof(cfg.est)); |
135 | cfg.opt.nla_type = TCA_STATS_RATE_EST; |
136 | cfg.est.interval = info->interval; |
137 | cfg.est.ewma_log = info->ewma_log; |
138 | |
139 | ret = gen_new_estimator(&est->bstats, &est->rstats, |
140 | &est->lock, &cfg.opt); |
141 | if (ret < 0) |
142 | goto err2; |
143 | |
144 | info->est = est; |
145 | xt_rateest_hash_insert(est); |
146 | return 0; |
147 | |
148 | err2: |
149 | kfree(est); |
150 | err1: |
151 | return ret; |
152 | } |
153 | |
154 | static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par) |
155 | { |
156 | struct xt_rateest_target_info *info = par->targinfo; |
157 | |
158 | xt_rateest_put(info->est); |
159 | } |
160 | |
161 | static struct xt_target xt_rateest_tg_reg __read_mostly = { |
162 | .name = "RATEEST", |
163 | .revision = 0, |
164 | .family = NFPROTO_UNSPEC, |
165 | .target = xt_rateest_tg, |
166 | .checkentry = xt_rateest_tg_checkentry, |
167 | .destroy = xt_rateest_tg_destroy, |
168 | .targetsize = sizeof(struct xt_rateest_target_info), |
169 | .me = THIS_MODULE, |
170 | }; |
171 | |
172 | static int __init xt_rateest_tg_init(void) |
173 | { |
174 | unsigned int i; |
175 | |
176 | for (i = 0; i < ARRAY_SIZE(rateest_hash); i++) |
177 | INIT_HLIST_HEAD(&rateest_hash[i]); |
178 | |
179 | return xt_register_target(&xt_rateest_tg_reg); |
180 | } |
181 | |
182 | static void __exit xt_rateest_tg_fini(void) |
183 | { |
184 | xt_unregister_target(&xt_rateest_tg_reg); |
185 | } |
186 | |
187 | |
188 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |
189 | MODULE_LICENSE("GPL"); |
190 | MODULE_DESCRIPTION("Xtables: packet rate estimator"); |
191 | MODULE_ALIAS("ipt_RATEEST"); |
192 | MODULE_ALIAS("ip6t_RATEEST"); |
193 | module_init(xt_rateest_tg_init); |
194 | module_exit(xt_rateest_tg_fini); |
195 |
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