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1 | /* Kernel module to match AH parameters. */ | |
2 | ||
3 | /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 as | |
7 | * published by the Free Software Foundation. | |
8 | */ | |
9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
10 | #include <linux/module.h> | |
11 | #include <linux/skbuff.h> | |
12 | #include <linux/ip.h> | |
13 | #include <linux/ipv6.h> | |
14 | #include <linux/types.h> | |
15 | #include <net/checksum.h> | |
16 | #include <net/ipv6.h> | |
17 | ||
18 | #include <linux/netfilter/x_tables.h> | |
19 | #include <linux/netfilter_ipv6/ip6_tables.h> | |
20 | #include <linux/netfilter_ipv6/ip6t_ah.h> | |
21 | ||
22 | MODULE_LICENSE("GPL"); | |
23 | MODULE_DESCRIPTION("Xtables: IPv6 IPsec-AH match"); | |
24 | MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); | |
25 | ||
26 | /* Returns 1 if the spi is matched by the range, 0 otherwise */ | |
27 | static inline bool | |
28 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert) | |
29 | { | |
30 | bool r; | |
31 | ||
32 | pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n", | |
33 | invert ? '!' : ' ', min, spi, max); | |
34 | r = (spi >= min && spi <= max) ^ invert; | |
35 | pr_debug(" result %s\n", r ? "PASS" : "FAILED"); | |
36 | return r; | |
37 | } | |
38 | ||
39 | static bool ah_mt6(const struct sk_buff *skb, const struct xt_match_param *par) | |
40 | { | |
41 | struct ip_auth_hdr _ah; | |
42 | const struct ip_auth_hdr *ah; | |
43 | const struct ip6t_ah *ahinfo = par->matchinfo; | |
44 | unsigned int ptr; | |
45 | unsigned int hdrlen = 0; | |
46 | int err; | |
47 | ||
48 | err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL); | |
49 | if (err < 0) { | |
50 | if (err != -ENOENT) | |
51 | *par->hotdrop = true; | |
52 | return false; | |
53 | } | |
54 | ||
55 | ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah); | |
56 | if (ah == NULL) { | |
57 | *par->hotdrop = true; | |
58 | return false; | |
59 | } | |
60 | ||
61 | hdrlen = (ah->hdrlen + 2) << 2; | |
62 | ||
63 | pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen); | |
64 | pr_debug("RES %04X ", ah->reserved); | |
65 | pr_debug("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi)); | |
66 | ||
67 | pr_debug("IPv6 AH spi %02X ", | |
68 | spi_match(ahinfo->spis[0], ahinfo->spis[1], | |
69 | ntohl(ah->spi), | |
70 | !!(ahinfo->invflags & IP6T_AH_INV_SPI))); | |
71 | pr_debug("len %02X %04X %02X ", | |
72 | ahinfo->hdrlen, hdrlen, | |
73 | (!ahinfo->hdrlen || | |
74 | (ahinfo->hdrlen == hdrlen) ^ | |
75 | !!(ahinfo->invflags & IP6T_AH_INV_LEN))); | |
76 | pr_debug("res %02X %04X %02X\n", | |
77 | ahinfo->hdrres, ah->reserved, | |
78 | !(ahinfo->hdrres && ah->reserved)); | |
79 | ||
80 | return (ah != NULL) && | |
81 | spi_match(ahinfo->spis[0], ahinfo->spis[1], | |
82 | ntohl(ah->spi), | |
83 | !!(ahinfo->invflags & IP6T_AH_INV_SPI)) && | |
84 | (!ahinfo->hdrlen || | |
85 | (ahinfo->hdrlen == hdrlen) ^ | |
86 | !!(ahinfo->invflags & IP6T_AH_INV_LEN)) && | |
87 | !(ahinfo->hdrres && ah->reserved); | |
88 | } | |
89 | ||
90 | static int ah_mt6_check(const struct xt_mtchk_param *par) | |
91 | { | |
92 | const struct ip6t_ah *ahinfo = par->matchinfo; | |
93 | ||
94 | if (ahinfo->invflags & ~IP6T_AH_INV_MASK) { | |
95 | pr_debug("unknown flags %X\n", ahinfo->invflags); | |
96 | return false; | |
97 | } | |
98 | return true; | |
99 | } | |
100 | ||
101 | static struct xt_match ah_mt6_reg __read_mostly = { | |
102 | .name = "ah", | |
103 | .family = NFPROTO_IPV6, | |
104 | .match = ah_mt6, | |
105 | .matchsize = sizeof(struct ip6t_ah), | |
106 | .checkentry = ah_mt6_check, | |
107 | .me = THIS_MODULE, | |
108 | }; | |
109 | ||
110 | static int __init ah_mt6_init(void) | |
111 | { | |
112 | return xt_register_match(&ah_mt6_reg); | |
113 | } | |
114 | ||
115 | static void __exit ah_mt6_exit(void) | |
116 | { | |
117 | xt_unregister_match(&ah_mt6_reg); | |
118 | } | |
119 | ||
120 | module_init(ah_mt6_init); | |
121 | module_exit(ah_mt6_exit); |