Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/* Kernel module to match AH parameters. */

/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#include <linux/in.h>

#include <linux/module.h>

#include <linux/skbuff.h>

#include <linux/ip.h>

#include <linux/netfilter_ipv4/ipt_ah.h>

#include <linux/netfilter/x_tables.h>

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");

MODULE_DESCRIPTION("iptables AH SPI match module");

#ifdef DEBUG_CONNTRACK

#define duprintf(format, args...) printk(format , ## args)

#else

#define duprintf(format, args...)

#endif

/* Returns 1 if the spi is matched by the range, 0 otherwise */

static inline bool

spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)

{

        bool r;

        duprintf("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',

                min,spi,max);

        r=(spi >= min && spi <= max) ^ invert;

        duprintf(" result %s\n",r? "PASS" : "FAILED");

        return r;

}

static bool

match(const struct sk_buff *skb,

      const struct net_device *in,

      const struct net_device *out,

      const struct xt_match *match,

      const void *matchinfo,

      int offset,

      unsigned int protoff,

      bool *hotdrop)

{

        struct ip_auth_hdr _ahdr;

        const struct ip_auth_hdr *ah;

        const struct ipt_ah *ahinfo = matchinfo;

        /* Must not be a fragment. */

        if (offset)

                return false;

        ah = skb_header_pointer(skb, protoff,

                                sizeof(_ahdr), &_ahdr);

        if (ah == NULL) {

                /* We've been asked to examine this packet, and we

                 * can't.  Hence, no choice but to drop.

                 */

                duprintf("Dropping evil AH tinygram.\n");

                *hotdrop = true;

                return 0;

        }

        return spi_match(ahinfo->spis[0], ahinfo->spis[1],

                         ntohl(ah->spi),

                         !!(ahinfo->invflags & IPT_AH_INV_SPI));

}

/* Called when user tries to insert an entry of this type. */

static bool

checkentry(const char *tablename,

           const void *ip_void,

           const struct xt_match *match,

           void *matchinfo,

           unsigned int hook_mask)

{

        const struct ipt_ah *ahinfo = matchinfo;

        /* Must specify no unknown invflags */

        if (ahinfo->invflags & ~IPT_AH_INV_MASK) {

                duprintf("ipt_ah: unknown flags %X\n", ahinfo->invflags);

                return false;

        }

        return true;

}

static struct xt_match ah_match __read_mostly = {

        .name           = "ah",

        .family         = AF_INET,

        .match          = match,

        .matchsize      = sizeof(struct ipt_ah),

        .proto          = IPPROTO_AH,

        .checkentry     = checkentry,

        .me             = THIS_MODULE,

};

static int __init ipt_ah_init(void)

{

        return xt_register_match(&ah_match);

}

static void __exit ipt_ah_fini(void)

{

        xt_unregister_match(&ah_match);

}

module_init(ipt_ah_init);

module_exit(ipt_ah_fini);