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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
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2 | /* |
3 | * Copyright (c) 2006 Patrick McHardy <kaber@trash.net> | |
4 | * | |
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5 | * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>. |
6 | */ | |
7 | ||
8 | #include <linux/init.h> | |
9 | #include <linux/spinlock.h> | |
10 | #include <linux/skbuff.h> | |
11 | #include <linux/net.h> | |
5a0e3ad6 | 12 | #include <linux/slab.h> |
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13 | |
14 | #include <linux/netfilter/xt_statistic.h> | |
15 | #include <linux/netfilter/x_tables.h> | |
3a9a231d | 16 | #include <linux/module.h> |
f3389805 | 17 | |
acc738fe | 18 | struct xt_statistic_priv { |
fabf3a85 ED |
19 | atomic_t count; |
20 | } ____cacheline_aligned_in_smp; | |
acc738fe | 21 | |
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22 | MODULE_LICENSE("GPL"); |
23 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
2ae15b64 | 24 | MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)"); |
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25 | MODULE_ALIAS("ipt_statistic"); |
26 | MODULE_ALIAS("ip6t_statistic"); | |
27 | ||
1d93a9cb | 28 | static bool |
62fc8051 | 29 | statistic_mt(const struct sk_buff *skb, struct xt_action_param *par) |
f3389805 | 30 | { |
acc738fe | 31 | const struct xt_statistic_info *info = par->matchinfo; |
1d93a9cb | 32 | bool ret = info->flags & XT_STATISTIC_INVERT; |
fabf3a85 | 33 | int nval, oval; |
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34 | |
35 | switch (info->mode) { | |
36 | case XT_STATISTIC_MODE_RANDOM: | |
a251c17a | 37 | if ((get_random_u32() & 0x7FFFFFFF) < info->u.random.probability) |
1d93a9cb | 38 | ret = !ret; |
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39 | break; |
40 | case XT_STATISTIC_MODE_NTH: | |
fabf3a85 ED |
41 | do { |
42 | oval = atomic_read(&info->master->count); | |
43 | nval = (oval == info->u.nth.every) ? 0 : oval + 1; | |
44 | } while (atomic_cmpxchg(&info->master->count, oval, nval) != oval); | |
45 | if (nval == 0) | |
1d93a9cb | 46 | ret = !ret; |
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47 | break; |
48 | } | |
49 | ||
50 | return ret; | |
51 | } | |
52 | ||
b0f38452 | 53 | static int statistic_mt_check(const struct xt_mtchk_param *par) |
f3389805 | 54 | { |
9b4fce7a | 55 | struct xt_statistic_info *info = par->matchinfo; |
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56 | |
57 | if (info->mode > XT_STATISTIC_MODE_MAX || | |
58 | info->flags & ~XT_STATISTIC_MASK) | |
bd414ee6 | 59 | return -EINVAL; |
acc738fe JE |
60 | |
61 | info->master = kzalloc(sizeof(*info->master), GFP_KERNEL); | |
85bc3f38 | 62 | if (info->master == NULL) |
4a5a5c73 | 63 | return -ENOMEM; |
fabf3a85 | 64 | atomic_set(&info->master->count, info->u.nth.count); |
acc738fe | 65 | |
bd414ee6 | 66 | return 0; |
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67 | } |
68 | ||
acc738fe JE |
69 | static void statistic_mt_destroy(const struct xt_mtdtor_param *par) |
70 | { | |
71 | const struct xt_statistic_info *info = par->matchinfo; | |
72 | ||
73 | kfree(info->master); | |
74 | } | |
75 | ||
55b69e91 JE |
76 | static struct xt_match xt_statistic_mt_reg __read_mostly = { |
77 | .name = "statistic", | |
78 | .revision = 0, | |
79 | .family = NFPROTO_UNSPEC, | |
80 | .match = statistic_mt, | |
81 | .checkentry = statistic_mt_check, | |
acc738fe | 82 | .destroy = statistic_mt_destroy, |
55b69e91 | 83 | .matchsize = sizeof(struct xt_statistic_info), |
1e98ffea | 84 | .usersize = offsetof(struct xt_statistic_info, master), |
55b69e91 | 85 | .me = THIS_MODULE, |
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86 | }; |
87 | ||
d3c5ee6d | 88 | static int __init statistic_mt_init(void) |
f3389805 | 89 | { |
55b69e91 | 90 | return xt_register_match(&xt_statistic_mt_reg); |
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91 | } |
92 | ||
d3c5ee6d | 93 | static void __exit statistic_mt_exit(void) |
f3389805 | 94 | { |
55b69e91 | 95 | xt_unregister_match(&xt_statistic_mt_reg); |
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96 | } |
97 | ||
d3c5ee6d JE |
98 | module_init(statistic_mt_init); |
99 | module_exit(statistic_mt_exit); |