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 <linux/export.h>
  16 #include <net/secure_seq.h>
  17 #include <net/netfilter/nf_nat.h>
  18 #include <net/netfilter/nf_nat_core.h>
  19 #include <net/netfilter/nf_nat_rule.h>
  20 #include <net/netfilter/nf_nat_protocol.h>
  21
  22 bool nf_nat_proto_in_range(const struct nf_conntrack_tuple *tuple,
  23                            enum nf_nat_manip_type maniptype,
  24                            const union nf_conntrack_man_proto *min,
  25                            const union nf_conntrack_man_proto *max)
  26 {
  27         __be16 port;
  28
  29         if (maniptype == IP_NAT_MANIP_SRC)
  30                 port = tuple->src.u.all;
  31         else
  32                 port = tuple->dst.u.all;
  33
  34         return ntohs(port) >= ntohs(min->all) &&
  35                ntohs(port) <= ntohs(max->all);
  36 }
  37 EXPORT_SYMBOL_GPL(nf_nat_proto_in_range);
  38
  39 void nf_nat_proto_unique_tuple(struct nf_conntrack_tuple *tuple,
  40                                const struct nf_nat_range *range,
  41                                enum nf_nat_manip_type maniptype,
  42                                const struct nf_conn *ct,
  43                                u_int16_t *rover)
  44 {
  45         unsigned int range_size, min, i;
  46         __be16 *portptr;
  47         u_int16_t off;
  48
  49         if (maniptype == IP_NAT_MANIP_SRC)
  50                 portptr = &tuple->src.u.all;
  51         else
  52                 portptr = &tuple->dst.u.all;
  53
  54         /* If no range specified... */
  55         if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
  56                 /* If it's dst rewrite, can't change port */
  57                 if (maniptype == IP_NAT_MANIP_DST)
  58                         return;
  59
  60                 if (ntohs(*portptr) < 1024) {
  61                         /* Loose convention: >> 512 is credential passing */
  62                         if (ntohs(*portptr) < 512) {
  63                                 min = 1;
  64                                 range_size = 511 - min + 1;
  65                         } else {
  66                                 min = 600;
  67                                 range_size = 1023 - min + 1;
  68                         }
  69                 } else {
  70                         min = 1024;
  71                         range_size = 65535 - 1024 + 1;
  72                 }
  73         } else {
  74                 min = ntohs(range->min.all);
  75                 range_size = ntohs(range->max.all) - min + 1;
  76         }
  77
  78         if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
  79                 off = secure_ipv4_port_ephemeral(tuple->src.u3.ip, tuple->dst.u3.ip,
  80                                                  maniptype == IP_NAT_MANIP_SRC
  81                                                  ? tuple->dst.u.all
  82                                                  : tuple->src.u.all);
  83         else
  84                 off = *rover;
  85
  86         for (i = 0; ; ++off) {
  87                 *portptr = htons(min + off % range_size);
  88                 if (++i != range_size && nf_nat_used_tuple(tuple, ct))
  89                         continue;
  90                 if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
  91                         *rover = off;
  92                 return;
  93         }
  94         return;
  95 }
  96 EXPORT_SYMBOL_GPL(nf_nat_proto_unique_tuple);
  97
  98 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
  99 int nf_nat_proto_range_to_nlattr(struct sk_buff *skb,
 100                                  const struct nf_nat_range *range)
 101 {
 102         NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MIN, range->min.all);
 103         NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MAX, range->max.all);
 104         return 0;
 105
 106 nla_put_failure:
 107         return -1;
 108 }
 109 EXPORT_SYMBOL_GPL(nf_nat_proto_nlattr_to_range);
 110
 111 int nf_nat_proto_nlattr_to_range(struct nlattr *tb[],
 112                                  struct nf_nat_range *range)
 113 {
 114         if (tb[CTA_PROTONAT_PORT_MIN]) {
 115                 range->min.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
 116                 range->max.all = range->min.tcp.port;
 117                 range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
 118         }
 119         if (tb[CTA_PROTONAT_PORT_MAX]) {
 120                 range->max.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
 121                 range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
 122         }
 123         return 0;
 124 }
 125 EXPORT_SYMBOL_GPL(nf_nat_proto_range_to_nlattr);
 126 #endif