161 lines
4.2 KiB
C
161 lines
4.2 KiB
C
/* 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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#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/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 <asm/div64.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, const struct net_device *in,
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const struct net_device *out, const struct xt_match *match,
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const void *matchinfo, int offset, unsigned int protoff,
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bool *hotdrop)
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{
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const struct xt_connbytes_info *sinfo = 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 ip_conntrack_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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counters = ct->counters;
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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 = 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 = 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 = counters[IP_CT_DIR_ORIGINAL].packets;
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what += 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 = 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 = 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 = counters[IP_CT_DIR_ORIGINAL].bytes;
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what += 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 = counters[IP_CT_DIR_ORIGINAL].bytes;
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pkts = 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 = counters[IP_CT_DIR_REPLY].bytes;
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pkts = 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 = counters[IP_CT_DIR_ORIGINAL].bytes +
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counters[IP_CT_DIR_REPLY].bytes;
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pkts = counters[IP_CT_DIR_ORIGINAL].packets +
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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_64(bytes, pkts);
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break;
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}
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if (sinfo->count.to)
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return what <= sinfo->count.to && what >= sinfo->count.from;
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else
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return what >= sinfo->count.from;
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}
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static bool
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connbytes_mt_check(const char *tablename, const void *ip,
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const struct xt_match *match, void *matchinfo,
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unsigned int hook_mask)
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{
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const struct xt_connbytes_info *sinfo = matchinfo;
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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 false;
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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 false;
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if (nf_ct_l3proto_try_module_get(match->family) < 0) {
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printk(KERN_WARNING "can't load conntrack support for "
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"proto=%u\n", match->family);
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return false;
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}
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return true;
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}
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static void
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connbytes_mt_destroy(const struct xt_match *match, void *matchinfo)
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{
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nf_ct_l3proto_module_put(match->family);
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}
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static struct xt_match connbytes_mt_reg[] __read_mostly = {
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{
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.name = "connbytes",
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.family = AF_INET,
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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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{
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.name = "connbytes",
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.family = AF_INET6,
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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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};
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static int __init connbytes_mt_init(void)
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{
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return xt_register_matches(connbytes_mt_reg,
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ARRAY_SIZE(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_matches(connbytes_mt_reg, ARRAY_SIZE(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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