The existing connection tracking subsystem in netfilter can only handle ipv4. There were basically two choices present to add connection tracking support for ipv6. We could either duplicate all of the ipv4 connection tracking code into an ipv6 counterpart, or (the choice taken by these patches) we could design a generic layer that could handle both ipv4 and ipv6 and thus requiring only one sub-protocol (TCP, UDP, etc.) connection tracking helper module to be written. In fact nf_conntrack is capable of working with any layer 3 protocol. The existing ipv4 specific conntrack code could also not deal with the pecularities of doing connection tracking on ipv6, which is also cured here. For example, these issues include: 1) ICMPv6 handling, which is used for neighbour discovery in ipv6 thus some messages such as these should not participate in connection tracking since effectively they are like ARP messages 2) fragmentation must be handled differently in ipv6, because the simplistic "defrag, connection track and NAT, refrag" (which the existing ipv4 connection tracking does) approach simply isn't feasible in ipv6 3) ipv6 extension header parsing must occur at the correct spots before and after connection tracking decisions, and there were no provisions for this in the existing connection tracking design 4) ipv6 has no need for stateful NAT The ipv4 specific conntrack layer is kept around, until all of the ipv4 specific conntrack helpers are ported over to nf_conntrack and it is feature complete. Once that occurs, the old conntrack stuff will get placed into the feature-removal-schedule and we will fully kill it off 6 months later. Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp> Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
161 lines
4 KiB
C
161 lines
4 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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* 2004-07-20 Harald Welte <laforge@netfilter.org>
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* - reimplemented to use per-connection accounting counters
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* - add functionality to match number of packets
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* - add functionality to match average packet size
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* - add support to match directions seperately
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*
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <net/netfilter/nf_conntrack_compat.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_connbytes.h>
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#include <asm/div64.h>
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#include <asm/bitops.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("iptables match for matching number of pkts/bytes per connection");
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/* 64bit divisor, dividend and result. dynamic precision */
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static u_int64_t div64_64(u_int64_t dividend, u_int64_t divisor)
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{
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u_int32_t d = divisor;
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if (divisor > 0xffffffffULL) {
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unsigned int shift = fls(divisor >> 32);
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d = divisor >> shift;
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dividend >>= shift;
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}
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do_div(dividend, d);
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return dividend;
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}
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static int
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match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const void *matchinfo,
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int offset,
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int *hotdrop)
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{
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const struct ipt_connbytes_info *sinfo = matchinfo;
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u_int64_t what = 0; /* initialize to make gcc happy */
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const struct ip_conntrack_counter *counters;
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if (!(counters = nf_ct_get_counters(skb)))
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return 0; /* no match */
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switch (sinfo->what) {
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case IPT_CONNBYTES_PKTS:
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switch (sinfo->direction) {
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case IPT_CONNBYTES_DIR_ORIGINAL:
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what = counters[IP_CT_DIR_ORIGINAL].packets;
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break;
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case IPT_CONNBYTES_DIR_REPLY:
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what = counters[IP_CT_DIR_REPLY].packets;
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break;
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case IPT_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 IPT_CONNBYTES_BYTES:
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switch (sinfo->direction) {
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case IPT_CONNBYTES_DIR_ORIGINAL:
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what = counters[IP_CT_DIR_ORIGINAL].bytes;
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break;
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case IPT_CONNBYTES_DIR_REPLY:
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what = counters[IP_CT_DIR_REPLY].bytes;
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break;
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case IPT_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 IPT_CONNBYTES_AVGPKT:
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switch (sinfo->direction) {
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case IPT_CONNBYTES_DIR_ORIGINAL:
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what = div64_64(counters[IP_CT_DIR_ORIGINAL].bytes,
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counters[IP_CT_DIR_ORIGINAL].packets);
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break;
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case IPT_CONNBYTES_DIR_REPLY:
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what = div64_64(counters[IP_CT_DIR_REPLY].bytes,
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counters[IP_CT_DIR_REPLY].packets);
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break;
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case IPT_CONNBYTES_DIR_BOTH:
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{
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u_int64_t bytes;
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u_int64_t pkts;
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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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/* FIXME_THEORETICAL: what to do if sum
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* overflows ? */
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what = div64_64(bytes, pkts);
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}
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break;
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}
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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 int check(const char *tablename,
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const struct ipt_ip *ip,
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void *matchinfo,
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unsigned int matchsize,
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unsigned int hook_mask)
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{
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const struct ipt_connbytes_info *sinfo = matchinfo;
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if (matchsize != IPT_ALIGN(sizeof(struct ipt_connbytes_info)))
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return 0;
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if (sinfo->what != IPT_CONNBYTES_PKTS &&
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sinfo->what != IPT_CONNBYTES_BYTES &&
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sinfo->what != IPT_CONNBYTES_AVGPKT)
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return 0;
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if (sinfo->direction != IPT_CONNBYTES_DIR_ORIGINAL &&
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sinfo->direction != IPT_CONNBYTES_DIR_REPLY &&
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sinfo->direction != IPT_CONNBYTES_DIR_BOTH)
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return 0;
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return 1;
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}
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static struct ipt_match state_match = {
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.name = "connbytes",
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.match = &match,
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.checkentry = &check,
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.me = THIS_MODULE
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};
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static int __init init(void)
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{
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return ipt_register_match(&state_match);
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}
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static void __exit fini(void)
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{
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ipt_unregister_match(&state_match);
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}
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module_init(init);
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module_exit(fini);
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