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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 | /* Kernel module to match ESP parameters. */
/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
*
* 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/in.h>
#include <linux/ip.h>
#include <linux/netfilter/xt_esp.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
MODULE_DESCRIPTION("x_tables ESP SPI match module");
MODULE_ALIAS("ipt_esp");
MODULE_ALIAS("ip6t_esp");
#if 0
#define duprintf(format, args...) printk(format , ## args)
#else
#define duprintf(format, args...)
#endif
/* Returns 1 if the spi is matched by the range, 0 otherwise */
static inline int
spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
{
int r = 0;
duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
min, spi, max);
r = (spi >= min && spi <= max) ^ invert;
duprintf(" result %s\n", r ? "PASS" : "FAILED");
return r;
}
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct xt_match *match,
const void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
struct ip_esp_hdr _esp, *eh;
const struct xt_esp *espinfo = matchinfo;
/* Must not be a fragment. */
if (offset)
return 0;
eh = skb_header_pointer(skb, protoff, sizeof(_esp), &_esp);
if (eh == NULL) {
/* We've been asked to examine this packet, and we
* can't. Hence, no choice but to drop.
*/
duprintf("Dropping evil ESP tinygram.\n");
*hotdrop = 1;
return 0;
}
return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),
!!(espinfo->invflags & XT_ESP_INV_SPI));
}
/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
const void *ip_void,
const struct xt_match *match,
void *matchinfo,
unsigned int matchinfosize,
unsigned int hook_mask)
{
const struct xt_esp *espinfo = matchinfo;
if (espinfo->invflags & ~XT_ESP_INV_MASK) {
duprintf("xt_esp: unknown flags %X\n", espinfo->invflags);
return 0;
}
return 1;
}
static struct xt_match esp_match = {
.name = "esp",
.family = AF_INET,
.proto = IPPROTO_ESP,
.match = &match,
.matchsize = sizeof(struct xt_esp),
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static struct xt_match esp6_match = {
.name = "esp",
.family = AF_INET6,
.proto = IPPROTO_ESP,
.match = &match,
.matchsize = sizeof(struct xt_esp),
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init xt_esp_init(void)
{
int ret;
ret = xt_register_match(&esp_match);
if (ret)
return ret;
ret = xt_register_match(&esp6_match);
if (ret)
xt_unregister_match(&esp_match);
return ret;
}
static void __exit xt_esp_cleanup(void)
{
xt_unregister_match(&esp_match);
xt_unregister_match(&esp6_match);
}
module_init(xt_esp_init);
module_exit(xt_esp_cleanup);
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