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root/net/ipv6/netfilter/ip6t_rt.c

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DEFINITIONS

This source file includes following definitions.
  1. segsleft_match
  2. rt_mt6
  3. rt_mt6_check
  4. rt_mt6_init
  5. rt_mt6_exit

/* Kernel module to match ROUTING parameters. */

/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
 *
 * 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/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <linux/types.h>
#include <net/checksum.h>
#include <net/ipv6.h>

#include <asm/byteorder.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_rt.h>

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");

/* Returns 1 if the id is matched by the range, 0 otherwise */
static inline bool
segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
{
        bool r;
        pr_debug("rt segsleft_match:%c 0x%x <= 0x%x <= 0x%x",
                 invert ? '!' : ' ', min, id, max);
        r = (id >= min && id <= max) ^ invert;
        pr_debug(" result %s\n", r ? "PASS" : "FAILED");
        return r;
}

static bool rt_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
{
        struct ipv6_rt_hdr _route;
        const struct ipv6_rt_hdr *rh;
        const struct ip6t_rt *rtinfo = par->matchinfo;
        unsigned int temp;
        unsigned int ptr;
        unsigned int hdrlen = 0;
        bool ret = false;
        struct in6_addr _addr;
        const struct in6_addr *ap;
        int err;

        err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
        if (err < 0) {
                if (err != -ENOENT)
                        *par->hotdrop = true;
                return false;
        }

        rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
        if (rh == NULL) {
                *par->hotdrop = true;
                return false;
        }

        hdrlen = ipv6_optlen(rh);
        if (skb->len - ptr < hdrlen) {
                /* Pcket smaller than its length field */
                return false;
        }

        pr_debug("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
        pr_debug("TYPE %04X ", rh->type);
        pr_debug("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);

        pr_debug("IPv6 RT segsleft %02X ",
                 segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
                                rh->segments_left,
                                !!(rtinfo->invflags & IP6T_RT_INV_SGS)));
        pr_debug("type %02X %02X %02X ",
                 rtinfo->rt_type, rh->type,
                 (!(rtinfo->flags & IP6T_RT_TYP) ||
                  ((rtinfo->rt_type == rh->type) ^
                   !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
        pr_debug("len %02X %04X %02X ",
                 rtinfo->hdrlen, hdrlen,
                 !(rtinfo->flags & IP6T_RT_LEN) ||
                  ((rtinfo->hdrlen == hdrlen) ^
                   !!(rtinfo->invflags & IP6T_RT_INV_LEN)));
        pr_debug("res %02X %02X %02X ",
                 rtinfo->flags & IP6T_RT_RES,
                 ((const struct rt0_hdr *)rh)->reserved,
                 !((rtinfo->flags & IP6T_RT_RES) &&
                   (((const struct rt0_hdr *)rh)->reserved)));

        ret = (rh != NULL)
              &&
              (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
                              rh->segments_left,
                              !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
              &&
              (!(rtinfo->flags & IP6T_RT_LEN) ||
               ((rtinfo->hdrlen == hdrlen) ^
                !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
              &&
              (!(rtinfo->flags & IP6T_RT_TYP) ||
               ((rtinfo->rt_type == rh->type) ^
                !!(rtinfo->invflags & IP6T_RT_INV_TYP)));

        if (ret && (rtinfo->flags & IP6T_RT_RES)) {
                const u_int32_t *rp;
                u_int32_t _reserved;
                rp = skb_header_pointer(skb,
                                        ptr + offsetof(struct rt0_hdr,
                                                       reserved),
                                        sizeof(_reserved),
                                        &_reserved);

                ret = (*rp == 0);
        }

        pr_debug("#%d ", rtinfo->addrnr);
        if (!(rtinfo->flags & IP6T_RT_FST)) {
                return ret;
        } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
                pr_debug("Not strict ");
                if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
                        pr_debug("There isn't enough space\n");
                        return false;
                } else {
                        unsigned int i = 0;

                        pr_debug("#%d ", rtinfo->addrnr);
                        for (temp = 0;
                             temp < (unsigned int)((hdrlen - 8) / 16);
                             temp++) {
                                ap = skb_header_pointer(skb,
                                                        ptr
                                                        + sizeof(struct rt0_hdr)
                                                        + temp * sizeof(_addr),
                                                        sizeof(_addr),
                                                        &_addr);

                                BUG_ON(ap == NULL);

                                if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
                                        pr_debug("i=%d temp=%d;\n", i, temp);
                                        i++;
                                }
                                if (i == rtinfo->addrnr)
                                        break;
                        }
                        pr_debug("i=%d #%d\n", i, rtinfo->addrnr);
                        if (i == rtinfo->addrnr)
                                return ret;
                        else
                                return false;
                }
        } else {
                pr_debug("Strict ");
                if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
                        pr_debug("There isn't enough space\n");
                        return false;
                } else {
                        pr_debug("#%d ", rtinfo->addrnr);
                        for (temp = 0; temp < rtinfo->addrnr; temp++) {
                                ap = skb_header_pointer(skb,
                                                        ptr
                                                        + sizeof(struct rt0_hdr)
                                                        + temp * sizeof(_addr),
                                                        sizeof(_addr),
                                                        &_addr);
                                BUG_ON(ap == NULL);

                                if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
                                        break;
                        }
                        pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr);
                        if (temp == rtinfo->addrnr &&
                            temp == (unsigned int)((hdrlen - 8) / 16))
                                return ret;
                        else
                                return false;
                }
        }

        return false;
}

static bool rt_mt6_check(const struct xt_mtchk_param *par)
{
        const struct ip6t_rt *rtinfo = par->matchinfo;

        if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
                pr_debug("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
                return false;
        }
        if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
            (!(rtinfo->flags & IP6T_RT_TYP) ||
             (rtinfo->rt_type != 0) ||
             (rtinfo->invflags & IP6T_RT_INV_TYP))) {
                pr_debug("`--rt-type 0' required before `--rt-0-*'");
                return false;
        }

        return true;
}

static struct xt_match rt_mt6_reg __read_mostly = {
        .name           = "rt",
        .family         = NFPROTO_IPV6,
        .match          = rt_mt6,
        .matchsize      = sizeof(struct ip6t_rt),
        .checkentry     = rt_mt6_check,
        .me             = THIS_MODULE,
};

static int __init rt_mt6_init(void)
{
        return xt_register_match(&rt_mt6_reg);
}

static void __exit rt_mt6_exit(void)
{
        xt_unregister_match(&rt_mt6_reg);
}

module_init(rt_mt6_init);
module_exit(rt_mt6_exit);

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