1 | /* Kernel module to match connection tracking byte counter. |
2 | * GPL (C) 2002 Martin Devera (devik@cdi.cz). |
3 | */ |
4 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
5 | #include <linux/module.h> |
6 | #include <linux/bitops.h> |
7 | #include <linux/skbuff.h> |
8 | #include <linux/math64.h> |
9 | #include <linux/netfilter/x_tables.h> |
10 | #include <linux/netfilter/xt_connbytes.h> |
11 | #include <net/netfilter/nf_conntrack.h> |
12 | #include <net/netfilter/nf_conntrack_acct.h> |
13 | |
14 | MODULE_LICENSE("GPL" ); |
15 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>" ); |
16 | MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching" ); |
17 | MODULE_ALIAS("ipt_connbytes" ); |
18 | MODULE_ALIAS("ip6t_connbytes" ); |
19 | |
20 | static bool |
21 | connbytes_mt(const struct sk_buff *skb, struct xt_action_param *par) |
22 | { |
23 | const struct xt_connbytes_info *sinfo = par->matchinfo; |
24 | const struct nf_conn *ct; |
25 | enum ip_conntrack_info ctinfo; |
26 | u_int64_t what = 0; /* initialize to make gcc happy */ |
27 | u_int64_t bytes = 0; |
28 | u_int64_t pkts = 0; |
29 | const struct nf_conn_acct *acct; |
30 | const struct nf_conn_counter *counters; |
31 | |
32 | ct = nf_ct_get(skb, ctinfo: &ctinfo); |
33 | if (!ct) |
34 | return false; |
35 | |
36 | acct = nf_conn_acct_find(ct); |
37 | if (!acct) |
38 | return false; |
39 | |
40 | counters = acct->counter; |
41 | switch (sinfo->what) { |
42 | case XT_CONNBYTES_PKTS: |
43 | switch (sinfo->direction) { |
44 | case XT_CONNBYTES_DIR_ORIGINAL: |
45 | what = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].packets); |
46 | break; |
47 | case XT_CONNBYTES_DIR_REPLY: |
48 | what = atomic64_read(v: &counters[IP_CT_DIR_REPLY].packets); |
49 | break; |
50 | case XT_CONNBYTES_DIR_BOTH: |
51 | what = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].packets); |
52 | what += atomic64_read(v: &counters[IP_CT_DIR_REPLY].packets); |
53 | break; |
54 | } |
55 | break; |
56 | case XT_CONNBYTES_BYTES: |
57 | switch (sinfo->direction) { |
58 | case XT_CONNBYTES_DIR_ORIGINAL: |
59 | what = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].bytes); |
60 | break; |
61 | case XT_CONNBYTES_DIR_REPLY: |
62 | what = atomic64_read(v: &counters[IP_CT_DIR_REPLY].bytes); |
63 | break; |
64 | case XT_CONNBYTES_DIR_BOTH: |
65 | what = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].bytes); |
66 | what += atomic64_read(v: &counters[IP_CT_DIR_REPLY].bytes); |
67 | break; |
68 | } |
69 | break; |
70 | case XT_CONNBYTES_AVGPKT: |
71 | switch (sinfo->direction) { |
72 | case XT_CONNBYTES_DIR_ORIGINAL: |
73 | bytes = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].bytes); |
74 | pkts = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].packets); |
75 | break; |
76 | case XT_CONNBYTES_DIR_REPLY: |
77 | bytes = atomic64_read(v: &counters[IP_CT_DIR_REPLY].bytes); |
78 | pkts = atomic64_read(v: &counters[IP_CT_DIR_REPLY].packets); |
79 | break; |
80 | case XT_CONNBYTES_DIR_BOTH: |
81 | bytes = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].bytes) + |
82 | atomic64_read(v: &counters[IP_CT_DIR_REPLY].bytes); |
83 | pkts = atomic64_read(v: &counters[IP_CT_DIR_ORIGINAL].packets) + |
84 | atomic64_read(v: &counters[IP_CT_DIR_REPLY].packets); |
85 | break; |
86 | } |
87 | if (pkts != 0) |
88 | what = div64_u64(dividend: bytes, divisor: pkts); |
89 | break; |
90 | } |
91 | |
92 | if (sinfo->count.to >= sinfo->count.from) |
93 | return what <= sinfo->count.to && what >= sinfo->count.from; |
94 | else /* inverted */ |
95 | return what < sinfo->count.to || what > sinfo->count.from; |
96 | } |
97 | |
98 | static int connbytes_mt_check(const struct xt_mtchk_param *par) |
99 | { |
100 | const struct xt_connbytes_info *sinfo = par->matchinfo; |
101 | int ret; |
102 | |
103 | if (sinfo->what != XT_CONNBYTES_PKTS && |
104 | sinfo->what != XT_CONNBYTES_BYTES && |
105 | sinfo->what != XT_CONNBYTES_AVGPKT) |
106 | return -EINVAL; |
107 | |
108 | if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL && |
109 | sinfo->direction != XT_CONNBYTES_DIR_REPLY && |
110 | sinfo->direction != XT_CONNBYTES_DIR_BOTH) |
111 | return -EINVAL; |
112 | |
113 | ret = nf_ct_netns_get(net: par->net, nfproto: par->family); |
114 | if (ret < 0) |
115 | pr_info_ratelimited("cannot load conntrack support for proto=%u\n" , |
116 | par->family); |
117 | |
118 | /* |
119 | * This filter cannot function correctly unless connection tracking |
120 | * accounting is enabled, so complain in the hope that someone notices. |
121 | */ |
122 | if (!nf_ct_acct_enabled(net: par->net)) { |
123 | pr_warn("Forcing CT accounting to be enabled\n" ); |
124 | nf_ct_set_acct(net: par->net, enable: true); |
125 | } |
126 | |
127 | return ret; |
128 | } |
129 | |
130 | static void connbytes_mt_destroy(const struct xt_mtdtor_param *par) |
131 | { |
132 | nf_ct_netns_put(net: par->net, nfproto: par->family); |
133 | } |
134 | |
135 | static struct xt_match connbytes_mt_reg __read_mostly = { |
136 | .name = "connbytes" , |
137 | .revision = 0, |
138 | .family = NFPROTO_UNSPEC, |
139 | .checkentry = connbytes_mt_check, |
140 | .match = connbytes_mt, |
141 | .destroy = connbytes_mt_destroy, |
142 | .matchsize = sizeof(struct xt_connbytes_info), |
143 | .me = THIS_MODULE, |
144 | }; |
145 | |
146 | static int __init connbytes_mt_init(void) |
147 | { |
148 | return xt_register_match(target: &connbytes_mt_reg); |
149 | } |
150 | |
151 | static void __exit connbytes_mt_exit(void) |
152 | { |
153 | xt_unregister_match(target: &connbytes_mt_reg); |
154 | } |
155 | |
156 | module_init(connbytes_mt_init); |
157 | module_exit(connbytes_mt_exit); |
158 | |