root/net/ipv4/netfilter/nf_nat_proto_common.c

DEFINITIONS

1. nf_nat_proto_in_range
2. nf_nat_proto_unique_tuple
3. nf_nat_proto_range_to_nlattr
4. nf_nat_proto_nlattr_to_range

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
 * (C) 2008 Patrick McHardy <kaber@trash.net>
 *
 * 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/ip.h>

#include <linux/netfilter.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_rule.h>
#include <net/netfilter/nf_nat_protocol.h>

bool nf_nat_proto_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 == IP_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_proto_in_range);

bool nf_nat_proto_unique_tuple(struct nf_conntrack_tuple *tuple,
                               const struct nf_nat_range *range,
                               enum nf_nat_manip_type maniptype,
                               const struct nf_conn *ct,
                               u_int16_t *rover)
{
        unsigned int range_size, min, i;
        __be16 *portptr;
        u_int16_t off;

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

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

                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.all);
                range_size = ntohs(range->max.all) - min + 1;
        }

        if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
                off = secure_ipv4_port_ephemeral(tuple->src.u3.ip, tuple->dst.u3.ip,
                                                 maniptype == IP_NAT_MANIP_SRC
                                                 ? tuple->dst.u.all
                                                 : tuple->src.u.all);
        else
                off = *rover;

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

#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
int nf_nat_proto_range_to_nlattr(struct sk_buff *skb,
                                 const struct nf_nat_range *range)
{
        NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MIN, range->min.all);
        NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MAX, range->max.all);
        return 0;

nla_put_failure:
        return -1;
}
EXPORT_SYMBOL_GPL(nf_nat_proto_nlattr_to_range);

int nf_nat_proto_nlattr_to_range(struct nlattr *tb[],
                                 struct nf_nat_range *range)
{
        if (tb[CTA_PROTONAT_PORT_MIN]) {
                range->min.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
                range->max.all = range->min.tcp.port;
                range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
        }
        if (tb[CTA_PROTONAT_PORT_MAX]) {
                range->max.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
                range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(nf_nat_proto_range_to_nlattr);
#endif