| 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 | |
| 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("IPv6 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("ah spi_match:%c 0x%x <= 0x%x <= 0x%x", |
| 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 |
| 40 | ah_mt6(const struct sk_buff *skb, const struct net_device *in, |
| 41 | const struct net_device *out, const struct xt_match *match, |
| 42 | const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop) |
| 43 | { |
| 44 | struct ip_auth_hdr _ah; |
| 45 | const struct ip_auth_hdr *ah; |
| 46 | const struct ip6t_ah *ahinfo = matchinfo; |
| 47 | unsigned int ptr; |
| 48 | unsigned int hdrlen = 0; |
| 49 | int err; |
| 50 | |
| 51 | err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL); |
| 52 | if (err < 0) { |
| 53 | if (err != -ENOENT) |
| 54 | *hotdrop = true; |
| 55 | return false; |
| 56 | } |
| 57 | |
| 58 | ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah); |
| 59 | if (ah == NULL) { |
| 60 | *hotdrop = true; |
| 61 | return false; |
| 62 | } |
| 63 | |
| 64 | hdrlen = (ah->hdrlen + 2) << 2; |
| 65 | |
| 66 | pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen); |
| 67 | pr_debug("RES %04X ", ah->reserved); |
| 68 | pr_debug("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi)); |
| 69 | |
| 70 | pr_debug("IPv6 AH spi %02X ", |
| 71 | spi_match(ahinfo->spis[0], ahinfo->spis[1], |
| 72 | ntohl(ah->spi), |
| 73 | !!(ahinfo->invflags & IP6T_AH_INV_SPI))); |
| 74 | pr_debug("len %02X %04X %02X ", |
| 75 | ahinfo->hdrlen, hdrlen, |
| 76 | (!ahinfo->hdrlen || |
| 77 | (ahinfo->hdrlen == hdrlen) ^ |
| 78 | !!(ahinfo->invflags & IP6T_AH_INV_LEN))); |
| 79 | pr_debug("res %02X %04X %02X\n", |
| 80 | ahinfo->hdrres, ah->reserved, |
| 81 | !(ahinfo->hdrres && ah->reserved)); |
| 82 | |
| 83 | return (ah != NULL) |
| 84 | && |
| 85 | spi_match(ahinfo->spis[0], ahinfo->spis[1], |
| 86 | ntohl(ah->spi), |
| 87 | !!(ahinfo->invflags & IP6T_AH_INV_SPI)) |
| 88 | && |
| 89 | (!ahinfo->hdrlen || |
| 90 | (ahinfo->hdrlen == hdrlen) ^ |
| 91 | !!(ahinfo->invflags & IP6T_AH_INV_LEN)) |
| 92 | && |
| 93 | !(ahinfo->hdrres && ah->reserved); |
| 94 | } |
| 95 | |
| 96 | /* Called when user tries to insert an entry of this type. */ |
| 97 | static bool |
| 98 | ah_mt6_check(const char *tablename, const void *entry, |
| 99 | const struct xt_match *match, void *matchinfo, |
| 100 | unsigned int hook_mask) |
| 101 | { |
| 102 | const struct ip6t_ah *ahinfo = matchinfo; |
| 103 | |
| 104 | if (ahinfo->invflags & ~IP6T_AH_INV_MASK) { |
| 105 | pr_debug("ip6t_ah: unknown flags %X\n", ahinfo->invflags); |
| 106 | return false; |
| 107 | } |
| 108 | return true; |
| 109 | } |
| 110 | |
| 111 | static struct xt_match ah_mt6_reg __read_mostly = { |
| 112 | .name = "ah", |
| 113 | .family = AF_INET6, |
| 114 | .match = ah_mt6, |
| 115 | .matchsize = sizeof(struct ip6t_ah), |
| 116 | .checkentry = ah_mt6_check, |
| 117 | .me = THIS_MODULE, |
| 118 | }; |
| 119 | |
| 120 | static int __init ah_mt6_init(void) |
| 121 | { |
| 122 | return xt_register_match(&ah_mt6_reg); |
| 123 | } |
| 124 | |
| 125 | static void __exit ah_mt6_exit(void) |
| 126 | { |
| 127 | xt_unregister_match(&ah_mt6_reg); |
| 128 | } |
| 129 | |
| 130 | module_init(ah_mt6_init); |
| 131 | module_exit(ah_mt6_exit); |