[NETFILTER]: Add new iptables "connbytes" match
This patch ads a new "connbytes" match that utilizes the CONFIG_NF_CT_ACCT
per-connection byte and packet counters. Using it you can do things like
packet classification on average packet size within a connection.
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/ipt_connbytes.c b/net/ipv4/netfilter/ipt_connbytes.c
new file mode 100644
index 0000000..0dfb52c
--- /dev/null
+++ b/net/ipv4/netfilter/ipt_connbytes.c
@@ -0,0 +1,166 @@
+/* Kernel module to match connection tracking byte counter.
+ * GPL (C) 2002 Martin Devera (devik@cdi.cz).
+ *
+ * 2004-07-20 Harald Welte <laforge@netfilter.org>
+ * - reimplemented to use per-connection accounting counters
+ * - add functionality to match number of packets
+ * - add functionality to match average packet size
+ * - add support to match directions seperately
+ *
+ */
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_connbytes.h>
+
+#include <asm/div64.h>
+#include <asm/bitops.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_DESCRIPTION("iptables match for matching number of pkts/bytes per connection");
+
+/* 64bit divisor, dividend and result. dynamic precision */
+static u_int64_t div64_64(u_int64_t divisor, u_int64_t dividend)
+{
+ u_int64_t result = divisor;
+
+ if (dividend > 0xffffffff) {
+ int first_bit = find_first_bit((unsigned long *) ÷nd, sizeof(dividend));
+ /* calculate number of bits to shift. shift exactly enough
+ * bits to make dividend fit in 32bits. */
+ int num_shift = (64 - 32 - first_bit);
+ /* first bit has to be < 32, since dividend was > 0xffffffff */
+ result = result >> num_shift;
+ dividend = dividend >> num_shift;
+ }
+
+ do_div(divisor, dividend);
+
+ return divisor;
+}
+
+static int
+match(const struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ const void *matchinfo,
+ int offset,
+ int *hotdrop)
+{
+ const struct ipt_connbytes_info *sinfo = matchinfo;
+ enum ip_conntrack_info ctinfo;
+ struct ip_conntrack *ct;
+ u_int64_t what = 0; /* initialize to make gcc happy */
+
+ if (!(ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo)))
+ return 0; /* no match */
+
+ switch (sinfo->what) {
+ case IPT_CONNBYTES_WHAT_PKTS:
+ switch (sinfo->direction) {
+ case IPT_CONNBYTES_DIR_ORIGINAL:
+ what = ct->counters[IP_CT_DIR_ORIGINAL].packets;
+ break;
+ case IPT_CONNBYTES_DIR_REPLY:
+ what = ct->counters[IP_CT_DIR_REPLY].packets;
+ break;
+ case IPT_CONNBYTES_DIR_BOTH:
+ what = ct->counters[IP_CT_DIR_ORIGINAL].packets;
+ what += ct->counters[IP_CT_DIR_REPLY].packets;
+ break;
+ }
+ break;
+ case IPT_CONNBYTES_WHAT_BYTES:
+ switch (sinfo->direction) {
+ case IPT_CONNBYTES_DIR_ORIGINAL:
+ what = ct->counters[IP_CT_DIR_ORIGINAL].bytes;
+ break;
+ case IPT_CONNBYTES_DIR_REPLY:
+ what = ct->counters[IP_CT_DIR_REPLY].bytes;
+ break;
+ case IPT_CONNBYTES_DIR_BOTH:
+ what = ct->counters[IP_CT_DIR_ORIGINAL].bytes;
+ what += ct->counters[IP_CT_DIR_REPLY].bytes;
+ break;
+ }
+ break;
+ case IPT_CONNBYTES_WHAT_AVGPKT:
+ switch (sinfo->direction) {
+ case IPT_CONNBYTES_DIR_ORIGINAL:
+ what = div64_64(ct->counters[IP_CT_DIR_ORIGINAL].bytes,
+ ct->counters[IP_CT_DIR_ORIGINAL].packets);
+ break;
+ case IPT_CONNBYTES_DIR_REPLY:
+ what = div64_64(ct->counters[IP_CT_DIR_REPLY].bytes,
+ ct->counters[IP_CT_DIR_REPLY].packets);
+ break;
+ case IPT_CONNBYTES_DIR_BOTH:
+ {
+ u_int64_t bytes;
+ u_int64_t pkts;
+ bytes = ct->counters[IP_CT_DIR_ORIGINAL].bytes +
+ ct->counters[IP_CT_DIR_REPLY].bytes;
+ pkts = ct->counters[IP_CT_DIR_ORIGINAL].packets+
+ ct->counters[IP_CT_DIR_REPLY].packets;
+
+ /* FIXME_THEORETICAL: what to do if sum
+ * overflows ? */
+
+ what = div64_64(bytes, pkts);
+ }
+ break;
+ }
+ break;
+ }
+
+ if (sinfo->count.to)
+ return (what <= sinfo->count.to && what >= sinfo->count.from);
+ else
+ return (what >= sinfo->count.from);
+}
+
+static int check(const char *tablename,
+ const struct ipt_ip *ip,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+ const struct ipt_connbytes_info *sinfo = matchinfo;
+
+ if (matchsize != IPT_ALIGN(sizeof(struct ipt_connbytes_info)))
+ return 0;
+
+ if (sinfo->what != IPT_CONNBYTES_WHAT_PKTS &&
+ sinfo->what != IPT_CONNBYTES_WHAT_BYTES &&
+ sinfo->what != IPT_CONNBYTES_WHAT_AVGPKT)
+ return 0;
+
+ if (sinfo->direction != IPT_CONNBYTES_DIR_ORIGINAL &&
+ sinfo->direction != IPT_CONNBYTES_DIR_REPLY &&
+ sinfo->direction != IPT_CONNBYTES_DIR_BOTH)
+ return 0;
+
+ return 1;
+}
+
+static struct ipt_match state_match = {
+ .name = "connbytes",
+ .match = &match,
+ .checkentry = &check,
+ .me = THIS_MODULE
+};
+
+static int __init init(void)
+{
+ return ipt_register_match(&state_match);
+}
+
+static void __exit fini(void)
+{
+ ipt_unregister_match(&state_match);
+}
+
+module_init(init);
+module_exit(fini);