nf_nat_proto_common.c

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/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <[email protected]>
 * (C) 2008 Patrick McHardy <[email protected]>
 *
 * 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/types.h>
#include <linux/random.h>
#include <linux/netfilter.h>
#include <linux/export.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_l3proto.h>
#include <net/netfilter/nf_nat_l4proto.h>

bool nf_nat_l4proto_in_range(const struct nf_conntrack_tuple *tuple,
                 enum nf_nat_manip_type maniptype,
                 const union nf_conntrack_man_proto *min,
                 const union nf_conntrack_man_proto *max)
{
    __be16 port;

    if (maniptype == NF_NAT_MANIP_SRC)
        port = tuple->src.u.all;
    else
        port = tuple->dst.u.all;

    return ntohs(port) >= ntohs(min->all) &&
           ntohs(port) <= ntohs(max->all);
}
EXPORT_SYMBOL_GPL(nf_nat_l4proto_in_range);

void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
                 struct nf_conntrack_tuple *tuple,
                 const struct nf_nat_range *range,
                 enum nf_nat_manip_type maniptype,
                 const struct nf_conn *ct,
                 u16 *rover)
{
    unsigned int range_size, min, i;
    __be16 *portptr;
    u_int16_t off;

    if (maniptype == NF_NAT_MANIP_SRC)
        portptr = &tuple->src.u.all;
    else
        portptr = &tuple->dst.u.all;

    /* If no range specified... */
    if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
        /* If it's dst rewrite, can't change port */
        if (maniptype == NF_NAT_MANIP_DST)
            return;

        if (ntohs(*portptr) < 1024) {
            /* Loose convention: >> 512 is credential passing */
            if (ntohs(*portptr) < 512) {
                min = 1;
                range_size = 511 - min + 1;
            } else {
                min = 600;
                range_size = 1023 - min + 1;
            }
        } else {
            min = 1024;
            range_size = 65535 - 1024 + 1;
        }
    } else {
        min = ntohs(range->min_proto.all);
        range_size = ntohs(range->max_proto.all) - min + 1;
    }

    if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
        off = l3proto->secure_port(tuple, maniptype == NF_NAT_MANIP_SRC
                          ? tuple->dst.u.all
                          : tuple->src.u.all);
    else
        off = *rover;

    for (i = 0; ; ++off) {
        *portptr = htons(min + off % range_size);
        if (++i != range_size && nf_nat_used_tuple(tuple, ct))
            continue;
        if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM))
            *rover = off;
        return;
    }
    return;
}
EXPORT_SYMBOL_GPL(nf_nat_l4proto_unique_tuple);

#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
                   struct nf_nat_range *range)
{
    if (tb[CTA_PROTONAT_PORT_MIN]) {
        range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
        range->max_proto.all = range->min_proto.all;
        range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
    }
    if (tb[CTA_PROTONAT_PORT_MAX]) {
        range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
        range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
    }
    return 0;
}
EXPORT_SYMBOL_GPL(nf_nat_l4proto_nlattr_to_range);
#endif