target/linux/generic-2.4/patches/605-netfilter_TTL.patch

   1 --- a/Documentation/Configure.help
   2 +++ b/Documentation/Configure.help
   3 @@ -3220,6 +3220,15 @@ CONFIG_IP_NF_TARGET_CLASSIFY
   4    If you want to compile it as a module, say M here and read
   5    Documentation/modules.txt.  If unsure, say `N'.
   6
   7 +TTL target support
   8 +CONFIG_IP_NF_TARGET_TTL
   9 +  This option adds a `TTL' target, which enables the user to set
  10 +  the TTL value or increment / decrement the TTL value by a given
  11 +  amount.
  12 +
  13 +  If you want to compile it as a module, say M here and read
  14 +  Documentation/modules.txt.  If unsure, say `N'.
  15 +
  16  ipchains (2.2-style) support
  17  CONFIG_IP_NF_COMPAT_IPCHAINS
  18    This option places ipchains (with masquerading and redirection
  19 --- /dev/null
  20 +++ b/include/linux/netfilter_ipv4/ipt_TTL.h
  21 @@ -0,0 +1,21 @@
  22 +/* TTL modification module for IP tables
  23 + * (C) 2000 by Harald Welte <laforge@gnumonks.org> */
  24 +
  25 +#ifndef _IPT_TTL_H
  26 +#define _IPT_TTL_H
  27 +
  28 +enum {
  29 +       IPT_TTL_SET = 0,
  30 +       IPT_TTL_INC,
  31 +       IPT_TTL_DEC
  32 +};
  33 +
  34 +#define IPT_TTL_MAXMODE        IPT_TTL_DEC
  35 +
  36 +struct ipt_TTL_info {
  37 +       u_int8_t        mode;
  38 +       u_int8_t        ttl;
  39 +};
  40 +
  41 +
  42 +#endif
  43 --- a/net/ipv4/netfilter/Config.in
  44 +++ b/net/ipv4/netfilter/Config.in
  45 @@ -126,6 +126,7 @@ if [ "$CONFIG_IP_NF_IPTABLES" != "n" ];
  46      dep_tristate '    CLASSIFY target support (EXPERIMENTAL)' CONFIG_IP_NF_TARGET_CLASSIFY $CONFIG_IP_NF_MANGLE
  47    fi
  48    dep_tristate '  LOG target support' CONFIG_IP_NF_TARGET_LOG $CONFIG_IP_NF_IPTABLES
  49 +  dep_tristate '  TTL target support' CONFIG_IP_NF_TARGET_TTL $CONFIG_IP_NF_IPTABLES
  50    dep_tristate '  ULOG target support' CONFIG_IP_NF_TARGET_ULOG $CONFIG_IP_NF_IPTABLES
  51    dep_tristate '  TCPMSS target support' CONFIG_IP_NF_TARGET_TCPMSS $CONFIG_IP_NF_IPTABLES
  52  fi
  53 --- /dev/null
  54 +++ b/net/ipv4/netfilter/ipt_TTL.c
  55 @@ -0,0 +1,110 @@
  56 +/* TTL modification target for IP tables
  57 + * (C) 2000 by Harald Welte <laforge@gnumonks.org>
  58 + *
  59 + * Version: $Revision: 1.1 $
  60 + *
  61 + * This software is distributed under the terms of GNU GPL
  62 + */
  63 +
  64 +#include <linux/module.h>
  65 +#include <linux/skbuff.h>
  66 +#include <linux/ip.h>
  67 +#include <net/checksum.h>
  68 +
  69 +#include <linux/netfilter_ipv4/ip_tables.h>
  70 +#include <linux/netfilter_ipv4/ipt_TTL.h>
  71 +
  72 +MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
  73 +MODULE_DESCRIPTION("IP tables TTL modification module");
  74 +MODULE_LICENSE("GPL");
  75 +
  76 +static unsigned int ipt_ttl_target(struct sk_buff **pskb, unsigned int hooknum,
  77 +               const struct net_device *in, const struct net_device *out,
  78 +               const void *targinfo, void *userinfo)
  79 +{
  80 +       struct iphdr *iph = (*pskb)->nh.iph;
  81 +       const struct ipt_TTL_info *info = targinfo;
  82 +       u_int16_t diffs[2];
  83 +       int new_ttl;
  84 +
  85 +       switch (info->mode) {
  86 +               case IPT_TTL_SET:
  87 +                       new_ttl = info->ttl;
  88 +                       break;
  89 +               case IPT_TTL_INC:
  90 +                       new_ttl = iph->ttl + info->ttl;
  91 +                       if (new_ttl > 255)
  92 +                               new_ttl = 255;
  93 +                       break;
  94 +               case IPT_TTL_DEC:
  95 +                       new_ttl = iph->ttl - info->ttl;
  96 +                       if (new_ttl < 0)
  97 +                               new_ttl = 0;
  98 +                       break;
  99 +               default:
 100 +                       new_ttl = iph->ttl;
 101 +                       break;
 102 +       }
 103 +
 104 +       if (new_ttl != iph->ttl) {
 105 +               diffs[0] = htons(((unsigned)iph->ttl) << 8) ^ 0xFFFF;
 106 +               iph->ttl = new_ttl;
 107 +               diffs[1] = htons(((unsigned)iph->ttl) << 8);
 108 +               iph->check = csum_fold(csum_partial((char *)diffs,
 109 +                                                   sizeof(diffs),
 110 +                                                   iph->check^0xFFFF));
 111 +                                                                                               (*pskb)->nfcache |= NFC_ALTERED;
 112 +       }
 113 +
 114 +       return IPT_CONTINUE;
 115 +}
 116 +
 117 +static int ipt_ttl_checkentry(const char *tablename,
 118 +               const struct ipt_entry *e,
 119 +               void *targinfo,
 120 +               unsigned int targinfosize,
 121 +               unsigned int hook_mask)
 122 +{
 123 +       struct ipt_TTL_info *info = targinfo;
 124 +
 125 +       if (targinfosize != IPT_ALIGN(sizeof(struct ipt_TTL_info))) {
 126 +               printk(KERN_WARNING "TTL: targinfosize %u != %Zu\n",
 127 +                               targinfosize,
 128 +                               IPT_ALIGN(sizeof(struct ipt_TTL_info)));
 129 +               return 0;
 130 +       }
 131 +
 132 +       if (strcmp(tablename, "mangle")) {
 133 +               printk(KERN_WARNING "TTL: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
 134 +               return 0;
 135 +       }
 136 +
 137 +       if (info->mode > IPT_TTL_MAXMODE) {
 138 +               printk(KERN_WARNING "TTL: invalid or unknown Mode %u\n",
 139 +                       info->mode);
 140 +               return 0;
 141 +       }
 142 +
 143 +       if ((info->mode != IPT_TTL_SET) && (info->ttl == 0)) {
 144 +               printk(KERN_WARNING "TTL: increment/decrement doesn't make sense with value 0\n");
 145 +               return 0;
 146 +       }
 147 +
 148 +       return 1;
 149 +}
 150 +
 151 +static struct ipt_target ipt_TTL = { { NULL, NULL }, "TTL",
 152 +       ipt_ttl_target, ipt_ttl_checkentry, NULL, THIS_MODULE };
 153 +
 154 +static int __init init(void)
 155 +{
 156 +       return ipt_register_target(&ipt_TTL);
 157 +}
 158 +
 159 +static void __exit fini(void)
 160 +{
 161 +       ipt_unregister_target(&ipt_TTL);
 162 +}
 163 +
 164 +module_init(init);
 165 +module_exit(fini);
 166 --- a/net/ipv4/netfilter/Makefile
 167 +++ b/net/ipv4/netfilter/Makefile
 168 @@ -110,6 +110,7 @@ obj-$(CONFIG_IP_NF_TARGET_MASQUERADE) +=
 169  obj-$(CONFIG_IP_NF_TARGET_REDIRECT) += ipt_REDIRECT.o
 170  obj-$(CONFIG_IP_NF_NAT_SNMP_BASIC) += ip_nat_snmp_basic.o
 171  obj-$(CONFIG_IP_NF_TARGET_LOG) += ipt_LOG.o
 172 +obj-$(CONFIG_IP_NF_TARGET_TTL) += ipt_TTL.o
 173  obj-$(CONFIG_IP_NF_TARGET_ULOG) += ipt_ULOG.o
 174  obj-$(CONFIG_IP_NF_TARGET_TCPMSS) += ipt_TCPMSS.o
 175