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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 | /* Kernel module to match FRAG parameters. */
/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
*
* 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/ipv6.h>
#include <linux/types.h>
#include <net/checksum.h>
#include <net/ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_frag.h>
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv6 FRAG match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
/* Returns 1 if the id is matched by the range, 0 otherwise */
static inline int
id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
{
int r = 0;
DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
min, id, max);
r = (id >= min && id <= max) ^ invert;
DEBUGP(" 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 void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
struct frag_hdr _frag, *fh;
const struct ip6t_frag *fraginfo = matchinfo;
unsigned int ptr;
if (ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL) < 0)
return 0;
fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
if (fh == NULL) {
*hotdrop = 1;
return 0;
}
DEBUGP("INFO %04X ", fh->frag_off);
DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF));
DEBUGP("ID %u %08X\n", ntohl(fh->identification),
ntohl(fh->identification));
DEBUGP("IPv6 FRAG id %02X ",
(id_match(fraginfo->ids[0], fraginfo->ids[1],
ntohl(fh->identification),
!!(fraginfo->invflags & IP6T_FRAG_INV_IDS))));
DEBUGP("res %02X %02X%04X %02X ",
(fraginfo->flags & IP6T_FRAG_RES), fh->reserved,
ntohs(fh->frag_off) & 0x6,
!((fraginfo->flags & IP6T_FRAG_RES)
&& (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
DEBUGP("first %02X %02X %02X ",
(fraginfo->flags & IP6T_FRAG_FST),
ntohs(fh->frag_off) & ~0x7,
!((fraginfo->flags & IP6T_FRAG_FST)
&& (ntohs(fh->frag_off) & ~0x7)));
DEBUGP("mf %02X %02X %02X ",
(fraginfo->flags & IP6T_FRAG_MF),
ntohs(fh->frag_off) & IP6_MF,
!((fraginfo->flags & IP6T_FRAG_MF)
&& !((ntohs(fh->frag_off) & IP6_MF))));
DEBUGP("last %02X %02X %02X\n",
(fraginfo->flags & IP6T_FRAG_NMF),
ntohs(fh->frag_off) & IP6_MF,
!((fraginfo->flags & IP6T_FRAG_NMF)
&& (ntohs(fh->frag_off) & IP6_MF)));
return (fh != NULL)
&&
(id_match(fraginfo->ids[0], fraginfo->ids[1],
ntohl(fh->identification),
!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))
&&
!((fraginfo->flags & IP6T_FRAG_RES)
&& (fh->reserved || (ntohs(fh->frag_off) & 0x6)))
&&
!((fraginfo->flags & IP6T_FRAG_FST)
&& (ntohs(fh->frag_off) & ~0x7))
&&
!((fraginfo->flags & IP6T_FRAG_MF)
&& !(ntohs(fh->frag_off) & IP6_MF))
&&
!((fraginfo->flags & IP6T_FRAG_NMF)
&& (ntohs(fh->frag_off) & IP6_MF));
}
/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
const void *ip,
void *matchinfo,
unsigned int matchinfosize,
unsigned int hook_mask)
{
const struct ip6t_frag *fraginfo = matchinfo;
if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_frag))) {
DEBUGP("ip6t_frag: matchsize %u != %u\n",
matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_frag)));
return 0;
}
if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
DEBUGP("ip6t_frag: unknown flags %X\n", fraginfo->invflags);
return 0;
}
return 1;
}
static struct ip6t_match frag_match = {
.name = "frag",
.match = &match,
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ip6t_register_match(&frag_match);
}
static void __exit cleanup(void)
{
ip6t_unregister_match(&frag_match);
}
module_init(init);
module_exit(cleanup);
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