release/src-rt-6.x.4708/linux/linux-2.6.36/net/ipv4/netfilter/nf_nat_proto_common.c

   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
  20 bool 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 }
  35 EXPORT_SYMBOL_GPL(nf_nat_proto_in_range);
  36
  37 void 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;
  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; ; ++off) {
  85                 *portptr = htons(min + off % range_size);
  86                 if (++i != range_size && nf_nat_used_tuple(tuple, ct))
  87                         continue;
  88                 if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
  89                         *rover = off;
  90                 return;
  91         }
  92         return;
  93 }
  94 EXPORT_SYMBOL_GPL(nf_nat_proto_unique_tuple);
  95
  96 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
  97 int 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
 104 nla_put_failure:
 105         return -1;
 106 }
 107 EXPORT_SYMBOL_GPL(nf_nat_proto_nlattr_to_range);
 108
 109 int 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 }
 123 EXPORT_SYMBOL_GPL(nf_nat_proto_range_to_nlattr);
 124 #endif