release/src-rt-6.x/linux/linux-2.6/net/ipv6/netfilter/ip6t_ah.c

   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 #if 0
  27 #define DEBUGP printk
  28 #else
  29 #define DEBUGP(format, args...)
  30 #endif
  31
  32 /* Returns 1 if the spi is matched by the range, 0 otherwise */
  33 static inline int
  34 spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
  35 {
  36         int r=0;
  37         DEBUGP("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
  38                min,spi,max);
  39         r = (spi >= min && spi <= max) ^ invert;
  40         DEBUGP(" result %s\n",r? "PASS\n" : "FAILED\n");
  41         return r;
  42 }
  43
  44 static int
  45 match(const struct sk_buff *skb,
  46       const struct net_device *in,
  47       const struct net_device *out,
  48       const struct xt_match *match,
  49       const void *matchinfo,
  50       int offset,
  51       unsigned int protoff,
  52       int *hotdrop)
  53 {
  54         struct ip_auth_hdr *ah, _ah;
  55         const struct ip6t_ah *ahinfo = matchinfo;
  56         unsigned int ptr;
  57         unsigned int hdrlen = 0;
  58         int err;
  59
  60         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL);
  61         if (err < 0) {
  62                 if (err != -ENOENT)
  63                         *hotdrop = 1;
  64                 return 0;
  65         }
  66
  67         ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
  68         if (ah == NULL) {
  69                 *hotdrop = 1;
  70                 return 0;
  71         }
  72
  73         hdrlen = (ah->hdrlen + 2) << 2;
  74
  75         DEBUGP("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
  76         DEBUGP("RES %04X ", ah->reserved);
  77         DEBUGP("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
  78
  79         DEBUGP("IPv6 AH spi %02X ",
  80                (spi_match(ahinfo->spis[0], ahinfo->spis[1],
  81                           ntohl(ah->spi),
  82                           !!(ahinfo->invflags & IP6T_AH_INV_SPI))));
  83         DEBUGP("len %02X %04X %02X ",
  84                ahinfo->hdrlen, hdrlen,
  85                (!ahinfo->hdrlen ||
  86                 (ahinfo->hdrlen == hdrlen) ^
  87                 !!(ahinfo->invflags & IP6T_AH_INV_LEN)));
  88         DEBUGP("res %02X %04X %02X\n",
  89                ahinfo->hdrres, ah->reserved,
  90                !(ahinfo->hdrres && ah->reserved));
  91
  92         return (ah != NULL)
  93                &&
  94                (spi_match(ahinfo->spis[0], ahinfo->spis[1],
  95                           ntohl(ah->spi),
  96                           !!(ahinfo->invflags & IP6T_AH_INV_SPI)))
  97                &&
  98                (!ahinfo->hdrlen ||
  99                 (ahinfo->hdrlen == hdrlen) ^
 100                 !!(ahinfo->invflags & IP6T_AH_INV_LEN))
 101                &&
 102                !(ahinfo->hdrres && ah->reserved);
 103 }
 104
 105 /* Called when user tries to insert an entry of this type. */
 106 static int
 107 checkentry(const char *tablename,
 108           const void *entry,
 109           const struct xt_match *match,
 110           void *matchinfo,
 111           unsigned int hook_mask)
 112 {
 113         const struct ip6t_ah *ahinfo = matchinfo;
 114
 115         if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
 116                 DEBUGP("ip6t_ah: unknown flags %X\n", ahinfo->invflags);
 117                 return 0;
 118         }
 119         return 1;
 120 }
 121
 122 static struct xt_match ah_match = {
 123         .name           = "ah",
 124         .family         = AF_INET6,
 125         .match          = match,
 126         .matchsize      = sizeof(struct ip6t_ah),
 127         .checkentry     = checkentry,
 128         .me             = THIS_MODULE,
 129 };
 130
 131 static int __init ip6t_ah_init(void)
 132 {
 133         return xt_register_match(&ah_match);
 134 }
 135
 136 static void __exit ip6t_ah_fini(void)
 137 {
 138         xt_unregister_match(&ah_match);
 139 }
 140
 141 module_init(ip6t_ah_init);
 142 module_exit(ip6t_ah_fini);