LXR linux/net/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/netfilter.h>
  13#include <linux/export.h>
  14
  15#include <net/netfilter/nf_nat.h>
  16#include <net/netfilter/nf_nat_core.h>
  17#include <net/netfilter/nf_nat_l3proto.h>
  18#include <net/netfilter/nf_nat_l4proto.h>
  19
  20bool nf_nat_l4proto_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 == NF_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_l4proto_in_range);
  36
  37void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
  38                                 struct nf_conntrack_tuple *tuple,
  39                                 const struct nf_nat_range *range,
  40                                 enum nf_nat_manip_type maniptype,
  41                                 const struct nf_conn *ct,
  42                                 u16 *rover)
  43{
  44        unsigned int range_size, min, i;
  45        __be16 *portptr;
  46        u_int16_t off;
  47
  48        if (maniptype == NF_NAT_MANIP_SRC)
  49                portptr = &tuple->src.u.all;
  50        else
  51                portptr = &tuple->dst.u.all;
  52
  53        /* If no range specified... */
  54        if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
  55                /* If it's dst rewrite, can't change port */
  56                if (maniptype == NF_NAT_MANIP_DST)
  57                        return;
  58
  59                if (ntohs(*portptr) < 1024) {
  60                        /* Loose convention: >> 512 is credential passing */
  61                        if (ntohs(*portptr) < 512) {
  62                                min = 1;
  63                                range_size = 511 - min + 1;
  64                        } else {
  65                                min = 600;
  66                                range_size = 1023 - min + 1;
  67                        }
  68                } else {
  69                        min = 1024;
  70                        range_size = 65535 - 1024 + 1;
  71                }
  72        } else {
  73                min = ntohs(range->min_proto.all);
  74                range_size = ntohs(range->max_proto.all) - min + 1;
  75        }
  76
  77        if (range->flags & NF_NAT_RANGE_PROTO_RANDOM) {
  78                off = l3proto->secure_port(tuple, maniptype == NF_NAT_MANIP_SRC
  79                                                  ? tuple->dst.u.all
  80                                                  : tuple->src.u.all);
  81        } else if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) {
  82                off = prandom_u32();
  83        } else {
  84                off = *rover;
  85        }
  86
  87        for (i = 0; ; ++off) {
  88                *portptr = htons(min + off % range_size);
  89                if (++i != range_size && nf_nat_used_tuple(tuple, ct))
  90                        continue;
  91                if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL))
  92                        *rover = off;
  93                return;
  94        }
  95}
  96EXPORT_SYMBOL_GPL(nf_nat_l4proto_unique_tuple);
  97
  98#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  99int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
 100                                   struct nf_nat_range *range)
 101{
 102        if (tb[CTA_PROTONAT_PORT_MIN]) {
 103                range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
 104                range->max_proto.all = range->min_proto.all;
 105                range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 106        }
 107        if (tb[CTA_PROTONAT_PORT_MAX]) {
 108                range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
 109                range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 110        }
 111        return 0;
 112}
 113EXPORT_SYMBOL_GPL(nf_nat_l4proto_nlattr_to_range);
 114#endif
 115