ebt_ip6.c

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/*
 *  ebt_ip6
 *
 *  Authors:
 *  Manohar Castelino <[email protected]>
 *  Kuo-Lang Tseng <[email protected]>
 *  Jan Engelhardt <[email protected]>
 *
 * Summary:
 * This is just a modification of the IPv4 code written by
 * Bart De Schuymer <[email protected]>
 * with the changes required to support IPv6
 *
 *  Jan, 2008
 */
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <linux/in.h>
#include <linux/module.h>
#include <net/dsfield.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_ip6.h>

union pkthdr {
    struct {
        __be16 src;
        __be16 dst;
    } tcpudphdr;
    struct {
        u8 type;
        u8 code;
    } icmphdr;
};

static bool
ebt_ip6_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct ebt_ip6_info *info = par->matchinfo;
    const struct ipv6hdr *ih6;
    struct ipv6hdr _ip6h;
    const union pkthdr *pptr;
    union pkthdr _pkthdr;

    ih6 = skb_header_pointer(skb, 0, sizeof(_ip6h), &_ip6h);
    if (ih6 == NULL)
        return false;
    if (info->bitmask & EBT_IP6_TCLASS &&
       FWINV(info->tclass != ipv6_get_dsfield(ih6), EBT_IP6_TCLASS))
        return false;
    if (FWINV(ipv6_masked_addr_cmp(&ih6->saddr, &info->smsk,
                       &info->saddr), EBT_IP6_SOURCE) ||
        FWINV(ipv6_masked_addr_cmp(&ih6->daddr, &info->dmsk,
                       &info->daddr), EBT_IP6_DEST))
        return false;
    if (info->bitmask & EBT_IP6_PROTO) {
        uint8_t nexthdr = ih6->nexthdr;
        __be16 frag_off;
        int offset_ph;

        offset_ph = ipv6_skip_exthdr(skb, sizeof(_ip6h), &nexthdr, &frag_off);
        if (offset_ph == -1)
            return false;
        if (FWINV(info->protocol != nexthdr, EBT_IP6_PROTO))
            return false;
        if (!(info->bitmask & ( EBT_IP6_DPORT |
                    EBT_IP6_SPORT | EBT_IP6_ICMP6)))
            return true;

        /* min icmpv6 headersize is 4, so sizeof(_pkthdr) is ok. */
        pptr = skb_header_pointer(skb, offset_ph, sizeof(_pkthdr),
                      &_pkthdr);
        if (pptr == NULL)
            return false;
        if (info->bitmask & EBT_IP6_DPORT) {
            u16 dst = ntohs(pptr->tcpudphdr.dst);
            if (FWINV(dst < info->dport[0] ||
                  dst > info->dport[1], EBT_IP6_DPORT))
                return false;
        }
        if (info->bitmask & EBT_IP6_SPORT) {
            u16 src = ntohs(pptr->tcpudphdr.src);
            if (FWINV(src < info->sport[0] ||
                  src > info->sport[1], EBT_IP6_SPORT))
            return false;
        }
        if ((info->bitmask & EBT_IP6_ICMP6) &&
             FWINV(pptr->icmphdr.type < info->icmpv6_type[0] ||
               pptr->icmphdr.type > info->icmpv6_type[1] ||
               pptr->icmphdr.code < info->icmpv6_code[0] ||
               pptr->icmphdr.code > info->icmpv6_code[1],
                            EBT_IP6_ICMP6))
            return false;
    }
    return true;
}

static int ebt_ip6_mt_check(const struct xt_mtchk_param *par)
{
    const struct ebt_entry *e = par->entryinfo;
    struct ebt_ip6_info *info = par->matchinfo;

    if (e->ethproto != htons(ETH_P_IPV6) || e->invflags & EBT_IPROTO)
        return -EINVAL;
    if (info->bitmask & ~EBT_IP6_MASK || info->invflags & ~EBT_IP6_MASK)
        return -EINVAL;
    if (info->bitmask & (EBT_IP6_DPORT | EBT_IP6_SPORT)) {
        if (info->invflags & EBT_IP6_PROTO)
            return -EINVAL;
        if (info->protocol != IPPROTO_TCP &&
            info->protocol != IPPROTO_UDP &&
            info->protocol != IPPROTO_UDPLITE &&
            info->protocol != IPPROTO_SCTP &&
            info->protocol != IPPROTO_DCCP)
            return -EINVAL;
    }
    if (info->bitmask & EBT_IP6_DPORT && info->dport[0] > info->dport[1])
        return -EINVAL;
    if (info->bitmask & EBT_IP6_SPORT && info->sport[0] > info->sport[1])
        return -EINVAL;
    if (info->bitmask & EBT_IP6_ICMP6) {
        if ((info->invflags & EBT_IP6_PROTO) ||
             info->protocol != IPPROTO_ICMPV6)
            return -EINVAL;
        if (info->icmpv6_type[0] > info->icmpv6_type[1] ||
            info->icmpv6_code[0] > info->icmpv6_code[1])
            return -EINVAL;
    }
    return 0;
}

static struct xt_match ebt_ip6_mt_reg __read_mostly = {
    .name       = "ip6",
    .revision   = 0,
    .family     = NFPROTO_BRIDGE,
    .match      = ebt_ip6_mt,
    .checkentry = ebt_ip6_mt_check,
    .matchsize  = sizeof(struct ebt_ip6_info),
    .me     = THIS_MODULE,
};

static int __init ebt_ip6_init(void)
{
    return xt_register_match(&ebt_ip6_mt_reg);
}

static void __exit ebt_ip6_fini(void)
{
    xt_unregister_match(&ebt_ip6_mt_reg);
}

module_init(ebt_ip6_init);
module_exit(ebt_ip6_fini);
MODULE_DESCRIPTION("Ebtables: IPv6 protocol packet match");
MODULE_AUTHOR("Kuo-Lang Tseng <[email protected]>");
MODULE_LICENSE("GPL");