root/net/ipv6/netfilter/ip6t_ah.c

DEFINITIONS

1. spi_match
2. ah_mt6
3. ah_mt6_check
4. ah_mt6_init
5. ah_mt6_exit

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Kernel module to match AH parameters. */
   3 
   4 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
   5  */
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7 #include <linux/module.h>
   8 #include <linux/skbuff.h>
   9 #include <linux/ip.h>
  10 #include <linux/ipv6.h>
  11 #include <linux/types.h>
  12 #include <net/checksum.h>
  13 #include <net/ipv6.h>
  14 
  15 #include <linux/netfilter/x_tables.h>
  16 #include <linux/netfilter_ipv6/ip6_tables.h>
  17 #include <linux/netfilter_ipv6/ip6t_ah.h>
  18 
  19 MODULE_LICENSE("GPL");
  20 MODULE_DESCRIPTION("Xtables: IPv6 IPsec-AH match");
  21 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  22 
  23 /* Returns 1 if the spi is matched by the range, 0 otherwise */
  24 static inline bool
  25 spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
  26 {
  27         bool r;
  28 
  29         pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
  30                  invert ? '!' : ' ', min, spi, max);
  31         r = (spi >= min && spi <= max) ^ invert;
  32         pr_debug(" result %s\n", r ? "PASS" : "FAILED");
  33         return r;
  34 }
  35 
  36 static bool ah_mt6(const struct sk_buff *skb, struct xt_action_param *par)
  37 {
  38         struct ip_auth_hdr _ah;
  39         const struct ip_auth_hdr *ah;
  40         const struct ip6t_ah *ahinfo = par->matchinfo;
  41         unsigned int ptr = 0;
  42         unsigned int hdrlen = 0;
  43         int err;
  44 
  45         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL, NULL);
  46         if (err < 0) {
  47                 if (err != -ENOENT)
  48                         par->hotdrop = true;
  49                 return false;
  50         }
  51 
  52         ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
  53         if (ah == NULL) {
  54                 par->hotdrop = true;
  55                 return false;
  56         }
  57 
  58         hdrlen = ipv6_authlen(ah);
  59 
  60         pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
  61         pr_debug("RES %04X ", ah->reserved);
  62         pr_debug("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
  63 
  64         pr_debug("IPv6 AH spi %02X ",
  65                  spi_match(ahinfo->spis[0], ahinfo->spis[1],
  66                            ntohl(ah->spi),
  67                            !!(ahinfo->invflags & IP6T_AH_INV_SPI)));
  68         pr_debug("len %02X %04X %02X ",
  69                  ahinfo->hdrlen, hdrlen,
  70                  (!ahinfo->hdrlen ||
  71                   (ahinfo->hdrlen == hdrlen) ^
  72                   !!(ahinfo->invflags & IP6T_AH_INV_LEN)));
  73         pr_debug("res %02X %04X %02X\n",
  74                  ahinfo->hdrres, ah->reserved,
  75                  !(ahinfo->hdrres && ah->reserved));
  76 
  77         return (ah != NULL) &&
  78                 spi_match(ahinfo->spis[0], ahinfo->spis[1],
  79                           ntohl(ah->spi),
  80                           !!(ahinfo->invflags & IP6T_AH_INV_SPI)) &&
  81                 (!ahinfo->hdrlen ||
  82                  (ahinfo->hdrlen == hdrlen) ^
  83                  !!(ahinfo->invflags & IP6T_AH_INV_LEN)) &&
  84                 !(ahinfo->hdrres && ah->reserved);
  85 }
  86 
  87 static int ah_mt6_check(const struct xt_mtchk_param *par)
  88 {
  89         const struct ip6t_ah *ahinfo = par->matchinfo;
  90 
  91         if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
  92                 pr_debug("unknown flags %X\n", ahinfo->invflags);
  93                 return -EINVAL;
  94         }
  95         return 0;
  96 }
  97 
  98 static struct xt_match ah_mt6_reg __read_mostly = {
  99         .name           = "ah",
 100         .family         = NFPROTO_IPV6,
 101         .match          = ah_mt6,
 102         .matchsize      = sizeof(struct ip6t_ah),
 103         .checkentry     = ah_mt6_check,
 104         .me             = THIS_MODULE,
 105 };
 106 
 107 static int __init ah_mt6_init(void)
 108 {
 109         return xt_register_match(&ah_mt6_reg);
 110 }
 111 
 112 static void __exit ah_mt6_exit(void)
 113 {
 114         xt_unregister_match(&ah_mt6_reg);
 115 }
 116 
 117 module_init(ah_mt6_init);
 118 module_exit(ah_mt6_exit);