/* Kernel module to match connection tracking byte counter.
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* GPL (C) 2002 Martin Devera (devik@cdi.cz).
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/skbuff.h>
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#include <linux/math64.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_connbytes.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_acct.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");
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MODULE_ALIAS("ipt_connbytes");
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MODULE_ALIAS("ip6t_connbytes");
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static bool
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connbytes_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_connbytes_info *sinfo = par->matchinfo;
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const struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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u_int64_t what = 0; /* initialize to make gcc happy */
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u_int64_t bytes = 0;
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u_int64_t pkts = 0;
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const struct nf_conn_acct *acct;
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const struct nf_conn_counter *counters;
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ct = nf_ct_get(skb, &ctinfo);
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if (!ct)
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return false;
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acct = nf_conn_acct_find(ct);
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if (!acct)
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return false;
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counters = acct->counter;
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switch (sinfo->what) {
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case XT_CONNBYTES_PKTS:
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switch (sinfo->direction) {
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case XT_CONNBYTES_DIR_ORIGINAL:
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what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
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break;
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case XT_CONNBYTES_DIR_REPLY:
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what = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
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break;
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case XT_CONNBYTES_DIR_BOTH:
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what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
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what += atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
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break;
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}
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break;
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case XT_CONNBYTES_BYTES:
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switch (sinfo->direction) {
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case XT_CONNBYTES_DIR_ORIGINAL:
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what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
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break;
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case XT_CONNBYTES_DIR_REPLY:
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what = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
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break;
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case XT_CONNBYTES_DIR_BOTH:
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what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
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what += atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
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break;
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}
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break;
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case XT_CONNBYTES_AVGPKT:
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switch (sinfo->direction) {
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case XT_CONNBYTES_DIR_ORIGINAL:
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bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
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pkts = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
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break;
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case XT_CONNBYTES_DIR_REPLY:
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bytes = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
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pkts = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
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break;
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case XT_CONNBYTES_DIR_BOTH:
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bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes) +
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atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
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pkts = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets) +
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atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
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break;
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}
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if (pkts != 0)
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what = div64_u64(bytes, pkts);
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break;
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}
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if (sinfo->count.to >= sinfo->count.from)
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return what <= sinfo->count.to && what >= sinfo->count.from;
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else /* inverted */
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return what < sinfo->count.to || what > sinfo->count.from;
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}
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static int connbytes_mt_check(const struct xt_mtchk_param *par)
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{
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const struct xt_connbytes_info *sinfo = par->matchinfo;
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int ret;
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if (sinfo->what != XT_CONNBYTES_PKTS &&
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sinfo->what != XT_CONNBYTES_BYTES &&
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sinfo->what != XT_CONNBYTES_AVGPKT)
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return -EINVAL;
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if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
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sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
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sinfo->direction != XT_CONNBYTES_DIR_BOTH)
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return -EINVAL;
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ret = nf_ct_netns_get(par->net, par->family);
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if (ret < 0)
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pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
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par->family);
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/*
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* This filter cannot function correctly unless connection tracking
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* accounting is enabled, so complain in the hope that someone notices.
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*/
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if (!nf_ct_acct_enabled(par->net)) {
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pr_warn("Forcing CT accounting to be enabled\n");
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nf_ct_set_acct(par->net, true);
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}
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return ret;
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}
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static void connbytes_mt_destroy(const struct xt_mtdtor_param *par)
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{
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nf_ct_netns_put(par->net, par->family);
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}
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static struct xt_match connbytes_mt_reg __read_mostly = {
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.name = "connbytes",
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.revision = 0,
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.family = NFPROTO_UNSPEC,
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.checkentry = connbytes_mt_check,
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.match = connbytes_mt,
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.destroy = connbytes_mt_destroy,
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.matchsize = sizeof(struct xt_connbytes_info),
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.me = THIS_MODULE,
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};
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static int __init connbytes_mt_init(void)
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{
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return xt_register_match(&connbytes_mt_reg);
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}
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static void __exit connbytes_mt_exit(void)
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{
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xt_unregister_match(&connbytes_mt_reg);
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}
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module_init(connbytes_mt_init);
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module_exit(connbytes_mt_exit);
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