LXR linux/net/netfilter/xt

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*  Kernel module to match IPComp parameters for IPv4 and IPv6
   3 *
   4 *  Copyright (C) 2013 WindRiver
   5 *
   6 *  Author:
   7 *  Fan Du <fan.du@windriver.com>
   8 *
   9 *  Based on:
  10 *  net/netfilter/xt_esp.c
  11 */
  12
  13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14#include <linux/in.h>
  15#include <linux/module.h>
  16#include <linux/skbuff.h>
  17#include <linux/ip.h>
  18
  19#include <linux/netfilter/xt_ipcomp.h>
  20#include <linux/netfilter/x_tables.h>
  21
  22MODULE_LICENSE("GPL");
  23MODULE_AUTHOR("Fan Du <fan.du@windriver.com>");
  24MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");
  25MODULE_ALIAS("ipt_ipcomp");
  26MODULE_ALIAS("ip6t_ipcomp");
  27
  28/* Returns 1 if the spi is matched by the range, 0 otherwise */
  29static inline bool
  30spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
  31{
  32        bool r;
  33        pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
  34                 invert ? '!' : ' ', min, spi, max);
  35        r = (spi >= min && spi <= max) ^ invert;
  36        pr_debug(" result %s\n", r ? "PASS" : "FAILED");
  37        return r;
  38}
  39
  40static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par)
  41{
  42        struct ip_comp_hdr _comphdr;
  43        const struct ip_comp_hdr *chdr;
  44        const struct xt_ipcomp *compinfo = par->matchinfo;
  45
  46        /* Must not be a fragment. */
  47        if (par->fragoff != 0)
  48                return false;
  49
  50        chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);
  51        if (chdr == NULL) {
  52                /* We've been asked to examine this packet, and we
  53                 * can't.  Hence, no choice but to drop.
  54                 */
  55                pr_debug("Dropping evil IPComp tinygram.\n");
  56                par->hotdrop = true;
  57                return false;
  58        }
  59
  60        return spi_match(compinfo->spis[0], compinfo->spis[1],
  61                         ntohs(chdr->cpi),
  62                         !!(compinfo->invflags & XT_IPCOMP_INV_SPI));
  63}
  64
  65static int comp_mt_check(const struct xt_mtchk_param *par)
  66{
  67        const struct xt_ipcomp *compinfo = par->matchinfo;
  68
  69        /* Must specify no unknown invflags */
  70        if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {
  71                pr_info_ratelimited("unknown flags %X\n", compinfo->invflags);
  72                return -EINVAL;
  73        }
  74        return 0;
  75}
  76
  77static struct xt_match comp_mt_reg[] __read_mostly = {
  78        {
  79                .name           = "ipcomp",
  80                .family         = NFPROTO_IPV4,
  81                .match          = comp_mt,
  82                .matchsize      = sizeof(struct xt_ipcomp),
  83                .proto          = IPPROTO_COMP,
  84                .checkentry     = comp_mt_check,
  85                .me             = THIS_MODULE,
  86        },
  87        {
  88                .name           = "ipcomp",
  89                .family         = NFPROTO_IPV6,
  90                .match          = comp_mt,
  91                .matchsize      = sizeof(struct xt_ipcomp),
  92                .proto          = IPPROTO_COMP,
  93                .checkentry     = comp_mt_check,
  94                .me             = THIS_MODULE,
  95        },
  96};
  97
  98static int __init comp_mt_init(void)
  99{
 100        return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
 101}
 102
 103static void __exit comp_mt_exit(void)
 104{
 105        xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
 106}
 107
 108module_init(comp_mt_init);
 109module_exit(comp_mt_exit);
 110