diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_limit.c')
| -rw-r--r-- | net/ipv4/netfilter/ipt_limit.c | 157 |
1 files changed, 0 insertions, 157 deletions
diff --git a/net/ipv4/netfilter/ipt_limit.c b/net/ipv4/netfilter/ipt_limit.c deleted file mode 100644 index 0c24dcc703a..00000000000 --- a/net/ipv4/netfilter/ipt_limit.c +++ /dev/null @@ -1,157 +0,0 @@ -/* Kernel module to control the rate - * - * 2 September 1999: Changed from the target RATE to the match - * `limit', removed logging. Did I mention that - * Alexey is a fucking genius? - * Rusty Russell (rusty@rustcorp.com.au). */ - -/* (C) 1999 Jérôme de Vivie <devivie@info.enserb.u-bordeaux.fr> - * (C) 1999 Hervé Eychenne <eychenne@info.enserb.u-bordeaux.fr> - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ - -#include <linux/module.h> -#include <linux/skbuff.h> -#include <linux/spinlock.h> -#include <linux/interrupt.h> - -#include <linux/netfilter_ipv4/ip_tables.h> -#include <linux/netfilter_ipv4/ipt_limit.h> - -MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Herve Eychenne <rv@wallfire.org>"); -MODULE_DESCRIPTION("iptables rate limit match"); - -/* The algorithm used is the Simple Token Bucket Filter (TBF) - * see net/sched/sch_tbf.c in the linux source tree - */ - -static DEFINE_SPINLOCK(limit_lock); - -/* Rusty: This is my (non-mathematically-inclined) understanding of - this algorithm. The `average rate' in jiffies becomes your initial - amount of credit `credit' and the most credit you can ever have - `credit_cap'. The `peak rate' becomes the cost of passing the - test, `cost'. - - `prev' tracks the last packet hit: you gain one credit per jiffy. - If you get credit balance more than this, the extra credit is - discarded. Every time the match passes, you lose `cost' credits; - if you don't have that many, the test fails. - - See Alexey's formal explanation in net/sched/sch_tbf.c. - - To get the maxmum range, we multiply by this factor (ie. you get N - credits per jiffy). We want to allow a rate as low as 1 per day - (slowest userspace tool allows), which means - CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32. ie. */ -#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24)) - -/* Repeated shift and or gives us all 1s, final shift and add 1 gives - * us the power of 2 below the theoretical max, so GCC simply does a - * shift. */ -#define _POW2_BELOW2(x) ((x)|((x)>>1)) -#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2)) -#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4)) -#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8)) -#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16)) -#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1) - -#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ) - -static int -ipt_limit_match(const struct sk_buff *skb, - const struct net_device *in, - const struct net_device *out, - const void *matchinfo, - int offset, - int *hotdrop) -{ - struct ipt_rateinfo *r = ((struct ipt_rateinfo *)matchinfo)->master; - unsigned long now = jiffies; - - spin_lock_bh(&limit_lock); - r->credit += (now - xchg(&r->prev, now)) * CREDITS_PER_JIFFY; - if (r->credit > r->credit_cap) - r->credit = r->credit_cap; - - if (r->credit >= r->cost) { - /* We're not limited. */ - r->credit -= r->cost; - spin_unlock_bh(&limit_lock); - return 1; - } - - spin_unlock_bh(&limit_lock); - return 0; -} - -/* Precision saver. */ -static u_int32_t -user2credits(u_int32_t user) -{ - /* If multiplying would overflow... */ - if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY)) - /* Divide first. */ - return (user / IPT_LIMIT_SCALE) * HZ * CREDITS_PER_JIFFY; - - return (user * HZ * CREDITS_PER_JIFFY) / IPT_LIMIT_SCALE; -} - -static int -ipt_limit_checkentry(const char *tablename, - const struct ipt_ip *ip, - void *matchinfo, - unsigned int matchsize, - unsigned int hook_mask) -{ - struct ipt_rateinfo *r = matchinfo; - - if (matchsize != IPT_ALIGN(sizeof(struct ipt_rateinfo))) - return 0; - - /* Check for overflow. */ - if (r->burst == 0 - || user2credits(r->avg * r->burst) < user2credits(r->avg)) { - printk("Overflow in ipt_limit, try lower: %u/%u\n", - r->avg, r->burst); - return 0; - } - - /* User avg in seconds * IPT_LIMIT_SCALE: convert to jiffies * - 128. */ - r->prev = jiffies; - r->credit = user2credits(r->avg * r->burst); /* Credits full. */ - r->credit_cap = user2credits(r->avg * r->burst); /* Credits full. */ - r->cost = user2credits(r->avg); - - /* For SMP, we only want to use one set of counters. */ - r->master = r; - - return 1; -} - -static struct ipt_match ipt_limit_reg = { - .name = "limit", - .match = ipt_limit_match, - .checkentry = ipt_limit_checkentry, - .me = THIS_MODULE, -}; - -static int __init init(void) -{ - if (ipt_register_match(&ipt_limit_reg)) - return -EINVAL; - return 0; -} - -static void __exit fini(void) -{ - ipt_unregister_match(&ipt_limit_reg); -} - -module_init(init); -module_exit(fini); |