1 /* Kernel module to match AH parameters. */
2 /* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
14 #include <linux/netfilter_ipv4/ipt_ah.h>
15 #include <linux/netfilter/x_tables.h>
17 MODULE_LICENSE("GPL");
18 MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
19 MODULE_DESCRIPTION("iptables AH SPI match module");
21 #ifdef DEBUG_CONNTRACK
22 #define duprintf(format, args...) printk(format , ## args)
24 #define duprintf(format, args...)
27 /* Returns 1 if the spi is matched by the range, 0 otherwise */
29 spi_match(u_int32_t min
, u_int32_t max
, u_int32_t spi
, bool invert
)
32 duprintf("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert
? '!':' ',
34 r
=(spi
>= min
&& spi
<= max
) ^ invert
;
35 duprintf(" result %s\n",r
? "PASS" : "FAILED");
40 match(const struct sk_buff
*skb
,
41 const struct net_device
*in
,
42 const struct net_device
*out
,
43 const struct xt_match
*match
,
44 const void *matchinfo
,
49 struct ip_auth_hdr _ahdr
;
50 const struct ip_auth_hdr
*ah
;
51 const struct ipt_ah
*ahinfo
= matchinfo
;
53 /* Must not be a fragment. */
57 ah
= skb_header_pointer(skb
, protoff
,
58 sizeof(_ahdr
), &_ahdr
);
60 /* We've been asked to examine this packet, and we
61 * can't. Hence, no choice but to drop.
63 duprintf("Dropping evil AH tinygram.\n");
68 return spi_match(ahinfo
->spis
[0], ahinfo
->spis
[1],
70 !!(ahinfo
->invflags
& IPT_AH_INV_SPI
));
73 /* Called when user tries to insert an entry of this type. */
75 checkentry(const char *tablename
,
77 const struct xt_match
*match
,
79 unsigned int hook_mask
)
81 const struct ipt_ah
*ahinfo
= matchinfo
;
83 /* Must specify no unknown invflags */
84 if (ahinfo
->invflags
& ~IPT_AH_INV_MASK
) {
85 duprintf("ipt_ah: unknown flags %X\n", ahinfo
->invflags
);
91 static struct xt_match ah_match
= {
95 .matchsize
= sizeof(struct ipt_ah
),
97 .checkentry
= checkentry
,
101 static int __init
ipt_ah_init(void)
103 return xt_register_match(&ah_match
);
106 static void __exit
ipt_ah_fini(void)
108 xt_unregister_match(&ah_match
);
111 module_init(ipt_ah_init
);
112 module_exit(ipt_ah_fini
);