1 | /* |
2 | * netfilter module to limit the number of parallel tcp |
3 | * connections per IP address. |
4 | * (c) 2000 Gerd Knorr <kraxel@bytesex.org> |
5 | * Nov 2002: Martin Bene <martin.bene@icomedias.com>: |
6 | * only ignore TIME_WAIT or gone connections |
7 | * (C) CC Computer Consultants GmbH, 2007 |
8 | * |
9 | * based on ... |
10 | * |
11 | * Kernel module to match connection tracking information. |
12 | * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au). |
13 | */ |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | |
16 | #include <linux/ip.h> |
17 | #include <linux/ipv6.h> |
18 | #include <linux/module.h> |
19 | #include <linux/skbuff.h> |
20 | #include <linux/netfilter/x_tables.h> |
21 | #include <linux/netfilter/xt_connlimit.h> |
22 | |
23 | #include <net/netfilter/nf_conntrack.h> |
24 | #include <net/netfilter/nf_conntrack_core.h> |
25 | #include <net/netfilter/nf_conntrack_tuple.h> |
26 | #include <net/netfilter/nf_conntrack_zones.h> |
27 | #include <net/netfilter/nf_conntrack_count.h> |
28 | |
29 | static bool |
30 | connlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) |
31 | { |
32 | struct net *net = xt_net(par); |
33 | const struct xt_connlimit_info *info = par->matchinfo; |
34 | struct nf_conntrack_tuple tuple; |
35 | const struct nf_conntrack_tuple *tuple_ptr = &tuple; |
36 | const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt; |
37 | enum ip_conntrack_info ctinfo; |
38 | const struct nf_conn *ct; |
39 | unsigned int connections; |
40 | u32 key[5]; |
41 | |
42 | ct = nf_ct_get(skb, ctinfo: &ctinfo); |
43 | if (ct != NULL) { |
44 | tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
45 | zone = nf_ct_zone(ct); |
46 | } else if (!nf_ct_get_tuplepr(skb, nhoff: skb_network_offset(skb), |
47 | l3num: xt_family(par), net, tuple: &tuple)) { |
48 | goto hotdrop; |
49 | } |
50 | |
51 | if (xt_family(par) == NFPROTO_IPV6) { |
52 | const struct ipv6hdr *iph = ipv6_hdr(skb); |
53 | union nf_inet_addr addr; |
54 | unsigned int i; |
55 | |
56 | memcpy(&addr.ip6, (info->flags & XT_CONNLIMIT_DADDR) ? |
57 | &iph->daddr : &iph->saddr, sizeof(addr.ip6)); |
58 | |
59 | for (i = 0; i < ARRAY_SIZE(addr.ip6); ++i) |
60 | addr.ip6[i] &= info->mask.ip6[i]; |
61 | memcpy(key, &addr, sizeof(addr.ip6)); |
62 | key[4] = zone->id; |
63 | } else { |
64 | const struct iphdr *iph = ip_hdr(skb); |
65 | |
66 | key[0] = (info->flags & XT_CONNLIMIT_DADDR) ? |
67 | (__force __u32)iph->daddr : (__force __u32)iph->saddr; |
68 | key[0] &= (__force __u32)info->mask.ip; |
69 | key[1] = zone->id; |
70 | } |
71 | |
72 | connections = nf_conncount_count(net, data: info->data, key, tuple: tuple_ptr, |
73 | zone); |
74 | if (connections == 0) |
75 | /* kmalloc failed, drop it entirely */ |
76 | goto hotdrop; |
77 | |
78 | return (connections > info->limit) ^ !!(info->flags & XT_CONNLIMIT_INVERT); |
79 | |
80 | hotdrop: |
81 | par->hotdrop = true; |
82 | return false; |
83 | } |
84 | |
85 | static int connlimit_mt_check(const struct xt_mtchk_param *par) |
86 | { |
87 | struct xt_connlimit_info *info = par->matchinfo; |
88 | unsigned int keylen; |
89 | |
90 | keylen = sizeof(u32); |
91 | if (par->family == NFPROTO_IPV6) |
92 | keylen += sizeof(struct in6_addr); |
93 | else |
94 | keylen += sizeof(struct in_addr); |
95 | |
96 | /* init private data */ |
97 | info->data = nf_conncount_init(net: par->net, family: par->family, keylen); |
98 | |
99 | return PTR_ERR_OR_ZERO(ptr: info->data); |
100 | } |
101 | |
102 | static void connlimit_mt_destroy(const struct xt_mtdtor_param *par) |
103 | { |
104 | const struct xt_connlimit_info *info = par->matchinfo; |
105 | |
106 | nf_conncount_destroy(net: par->net, family: par->family, data: info->data); |
107 | } |
108 | |
109 | static struct xt_match connlimit_mt_reg __read_mostly = { |
110 | .name = "connlimit" , |
111 | .revision = 1, |
112 | .family = NFPROTO_UNSPEC, |
113 | .checkentry = connlimit_mt_check, |
114 | .match = connlimit_mt, |
115 | .matchsize = sizeof(struct xt_connlimit_info), |
116 | .usersize = offsetof(struct xt_connlimit_info, data), |
117 | .destroy = connlimit_mt_destroy, |
118 | .me = THIS_MODULE, |
119 | }; |
120 | |
121 | static int __init connlimit_mt_init(void) |
122 | { |
123 | return xt_register_match(target: &connlimit_mt_reg); |
124 | } |
125 | |
126 | static void __exit connlimit_mt_exit(void) |
127 | { |
128 | xt_unregister_match(target: &connlimit_mt_reg); |
129 | } |
130 | |
131 | module_init(connlimit_mt_init); |
132 | module_exit(connlimit_mt_exit); |
133 | MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>" ); |
134 | MODULE_DESCRIPTION("Xtables: Number of connections matching" ); |
135 | MODULE_LICENSE("GPL" ); |
136 | MODULE_ALIAS("ipt_connlimit" ); |
137 | MODULE_ALIAS("ip6t_connlimit" ); |
138 | |