LXR linux/net/ipv4/netfilter/nf_nat_proto

   1/* (C) 1999-2001 Paul `Rusty' Russell
   2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   3 * (C) 2008 Patrick McHardy <kaber@trash.net>
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 as
   7 * published by the Free Software Foundation.
   8 */
   9
  10#include <linux/types.h>
  11#include <linux/random.h>
  12#include <linux/ip.h>
  13
  14#include <linux/netfilter.h>
  15#include <net/netfilter/nf_nat.h>
  16#include <net/netfilter/nf_nat_core.h>
  17#include <net/netfilter/nf_nat_rule.h>
  18#include <net/netfilter/nf_nat_protocol.h>
  19
  20bool nf_nat_proto_in_range(const struct nf_conntrack_tuple *tuple,
  21                           enum nf_nat_manip_type maniptype,
  22                           const union nf_conntrack_man_proto *min,
  23                           const union nf_conntrack_man_proto *max)
  24{
  25        __be16 port;
  26
  27        if (maniptype == IP_NAT_MANIP_SRC)
  28                port = tuple->src.u.all;
  29        else
  30                port = tuple->dst.u.all;
  31
  32        return ntohs(port) >= ntohs(min->all) &&
  33               ntohs(port) <= ntohs(max->all);
  34}
  35EXPORT_SYMBOL_GPL(nf_nat_proto_in_range);
  36
  37bool nf_nat_proto_unique_tuple(struct nf_conntrack_tuple *tuple,
  38                               const struct nf_nat_range *range,
  39                               enum nf_nat_manip_type maniptype,
  40                               const struct nf_conn *ct,
  41                               u_int16_t *rover)
  42{
  43        unsigned int range_size, min, i;
  44        __be16 *portptr;
  45        u_int16_t off;
  46
  47        if (maniptype == IP_NAT_MANIP_SRC)
  48                portptr = &tuple->src.u.all;
  49        else
  50                portptr = &tuple->dst.u.all;
  51
  52        /* If no range specified... */
  53        if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
  54                /* If it's dst rewrite, can't change port */
  55                if (maniptype == IP_NAT_MANIP_DST)
  56                        return false;
  57
  58                if (ntohs(*portptr) < 1024) {
  59                        /* Loose convention: >> 512 is credential passing */
  60                        if (ntohs(*portptr) < 512) {
  61                                min = 1;
  62                                range_size = 511 - min + 1;
  63                        } else {
  64                                min = 600;
  65                                range_size = 1023 - min + 1;
  66                        }
  67                } else {
  68                        min = 1024;
  69                        range_size = 65535 - 1024 + 1;
  70                }
  71        } else {
  72                min = ntohs(range->min.all);
  73                range_size = ntohs(range->max.all) - min + 1;
  74        }
  75
  76        if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
  77                off = secure_ipv4_port_ephemeral(tuple->src.u3.ip, tuple->dst.u3.ip,
  78                                                 maniptype == IP_NAT_MANIP_SRC
  79                                                 ? tuple->dst.u.all
  80                                                 : tuple->src.u.all);
  81        else
  82                off = *rover;
  83
  84        for (i = 0; i < range_size; i++, off++) {
  85                *portptr = htons(min + off % range_size);
  86                if (nf_nat_used_tuple(tuple, ct))
  87                        continue;
  88                if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
  89                        *rover = off;
  90                return true;
  91        }
  92        return false;
  93}
  94EXPORT_SYMBOL_GPL(nf_nat_proto_unique_tuple);
  95
  96#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
  97int nf_nat_proto_range_to_nlattr(struct sk_buff *skb,
  98                                 const struct nf_nat_range *range)
  99{
 100        NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MIN, range->min.all);
 101        NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MAX, range->max.all);
 102        return 0;
 103
 104nla_put_failure:
 105        return -1;
 106}
 107EXPORT_SYMBOL_GPL(nf_nat_proto_nlattr_to_range);
 108
 109int nf_nat_proto_nlattr_to_range(struct nlattr *tb[],
 110                                 struct nf_nat_range *range)
 111{
 112        if (tb[CTA_PROTONAT_PORT_MIN]) {
 113                range->min.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
 114                range->max.all = range->min.tcp.port;
 115                range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
 116        }
 117        if (tb[CTA_PROTONAT_PORT_MAX]) {
 118                range->max.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
 119                range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
 120        }
 121        return 0;
 122}
 123EXPORT_SYMBOL_GPL(nf_nat_proto_range_to_nlattr);
 124#endif
 125