Commit | Line | Data |
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1da177e4 LT |
1 | /* Kernel module to match AH parameters. */ |
2 | /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> | |
3 | * | |
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. | |
7 | */ | |
8 | ||
6709dbbb | 9 | #include <linux/in.h> |
1da177e4 LT |
10 | #include <linux/module.h> |
11 | #include <linux/skbuff.h> | |
12 | #include <linux/ip.h> | |
13 | ||
14 | #include <linux/netfilter_ipv4/ipt_ah.h> | |
6709dbbb | 15 | #include <linux/netfilter/x_tables.h> |
1da177e4 LT |
16 | |
17 | MODULE_LICENSE("GPL"); | |
18 | MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); | |
19 | MODULE_DESCRIPTION("iptables AH SPI match module"); | |
20 | ||
21 | #ifdef DEBUG_CONNTRACK | |
22 | #define duprintf(format, args...) printk(format , ## args) | |
23 | #else | |
24 | #define duprintf(format, args...) | |
25 | #endif | |
26 | ||
27 | /* Returns 1 if the spi is matched by the range, 0 otherwise */ | |
1d93a9cb JE |
28 | static inline bool |
29 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert) | |
1da177e4 | 30 | { |
1d93a9cb | 31 | bool r; |
e905a9ed YH |
32 | duprintf("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', |
33 | min,spi,max); | |
1da177e4 LT |
34 | r=(spi >= min && spi <= max) ^ invert; |
35 | duprintf(" result %s\n",r? "PASS" : "FAILED"); | |
36 | return r; | |
37 | } | |
38 | ||
1d93a9cb | 39 | static bool |
1da177e4 LT |
40 | match(const struct sk_buff *skb, |
41 | const struct net_device *in, | |
42 | const struct net_device *out, | |
c4986734 | 43 | const struct xt_match *match, |
1da177e4 LT |
44 | const void *matchinfo, |
45 | int offset, | |
2e4e6a17 | 46 | unsigned int protoff, |
cff533ac | 47 | bool *hotdrop) |
1da177e4 | 48 | { |
a47362a2 JE |
49 | struct ip_auth_hdr _ahdr; |
50 | const struct ip_auth_hdr *ah; | |
1da177e4 LT |
51 | const struct ipt_ah *ahinfo = matchinfo; |
52 | ||
53 | /* Must not be a fragment. */ | |
54 | if (offset) | |
1d93a9cb | 55 | return false; |
1da177e4 | 56 | |
2e4e6a17 | 57 | ah = skb_header_pointer(skb, protoff, |
1da177e4 LT |
58 | sizeof(_ahdr), &_ahdr); |
59 | if (ah == NULL) { | |
60 | /* We've been asked to examine this packet, and we | |
61 | * can't. Hence, no choice but to drop. | |
62 | */ | |
63 | duprintf("Dropping evil AH tinygram.\n"); | |
cff533ac | 64 | *hotdrop = true; |
1da177e4 LT |
65 | return 0; |
66 | } | |
67 | ||
68 | return spi_match(ahinfo->spis[0], ahinfo->spis[1], | |
69 | ntohl(ah->spi), | |
70 | !!(ahinfo->invflags & IPT_AH_INV_SPI)); | |
71 | } | |
72 | ||
73 | /* Called when user tries to insert an entry of this type. */ | |
ccb79bdc | 74 | static bool |
1da177e4 | 75 | checkentry(const char *tablename, |
2e4e6a17 | 76 | const void *ip_void, |
c4986734 | 77 | const struct xt_match *match, |
1da177e4 | 78 | void *matchinfo, |
1da177e4 LT |
79 | unsigned int hook_mask) |
80 | { | |
81 | const struct ipt_ah *ahinfo = matchinfo; | |
82 | ||
1d5cd909 | 83 | /* Must specify no unknown invflags */ |
1da177e4 | 84 | if (ahinfo->invflags & ~IPT_AH_INV_MASK) { |
1d5cd909 | 85 | duprintf("ipt_ah: unknown flags %X\n", ahinfo->invflags); |
ccb79bdc | 86 | return false; |
1da177e4 | 87 | } |
ccb79bdc | 88 | return true; |
1da177e4 LT |
89 | } |
90 | ||
6709dbbb | 91 | static struct xt_match ah_match = { |
1da177e4 | 92 | .name = "ah", |
6709dbbb | 93 | .family = AF_INET, |
1d5cd909 PM |
94 | .match = match, |
95 | .matchsize = sizeof(struct ipt_ah), | |
96 | .proto = IPPROTO_AH, | |
97 | .checkentry = checkentry, | |
1da177e4 LT |
98 | .me = THIS_MODULE, |
99 | }; | |
100 | ||
65b4b4e8 | 101 | static int __init ipt_ah_init(void) |
1da177e4 | 102 | { |
6709dbbb | 103 | return xt_register_match(&ah_match); |
1da177e4 LT |
104 | } |
105 | ||
65b4b4e8 | 106 | static void __exit ipt_ah_fini(void) |
1da177e4 | 107 | { |
6709dbbb | 108 | xt_unregister_match(&ah_match); |
1da177e4 LT |
109 | } |
110 | ||
65b4b4e8 AM |
111 | module_init(ipt_ah_init); |
112 | module_exit(ipt_ah_fini); |