LXR linux/net/ipv6/netfilter/ip6t

   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
  22MODULE_LICENSE("GPL");
  23MODULE_DESCRIPTION("Xtables: IPv6 IPsec-AH match");
  24MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  25
  26/* Returns 1 if the spi is matched by the range, 0 otherwise */
  27static inline bool
  28spi_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
  39static bool
  40ah_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. */
  97static bool
  98ah_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
 111static 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
 120static int __init ah_mt6_init(void)
 121{
 122        return xt_register_match(&ah_mt6_reg);
 123}
 124
 125static void __exit ah_mt6_exit(void)
 126{
 127        xt_unregister_match(&ah_mt6_reg);
 128}
 129
 130module_init(ah_mt6_init);
 131module_exit(ah_mt6_exit);
 132