LXR linux/net/bridge/netfilter/ebt

   1/*
   2 *  ebt_ip
   3 *
   4 *      Authors:
   5 *      Bart De Schuymer <bdschuym@pandora.be>
   6 *
   7 *  April, 2002
   8 *
   9 *  Changes:
  10 *    added ip-sport and ip-dport
  11 *    Innominate Security Technologies AG <mhopf@innominate.com>
  12 *    September, 2002
  13 */
  14#include <linux/ip.h>
  15#include <net/ip.h>
  16#include <linux/in.h>
  17#include <linux/module.h>
  18#include <linux/netfilter/x_tables.h>
  19#include <linux/netfilter_bridge/ebtables.h>
  20#include <linux/netfilter_bridge/ebt_ip.h>
  21
  22struct tcpudphdr {
  23        __be16 src;
  24        __be16 dst;
  25};
  26
  27static bool
  28ebt_ip_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  29{
  30        const struct ebt_ip_info *info = par->matchinfo;
  31        const struct iphdr *ih;
  32        struct iphdr _iph;
  33        const struct tcpudphdr *pptr;
  34        struct tcpudphdr _ports;
  35
  36        ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
  37        if (ih == NULL)
  38                return false;
  39        if (info->bitmask & EBT_IP_TOS &&
  40           FWINV(info->tos != ih->tos, EBT_IP_TOS))
  41                return false;
  42        if (info->bitmask & EBT_IP_SOURCE &&
  43           FWINV((ih->saddr & info->smsk) !=
  44           info->saddr, EBT_IP_SOURCE))
  45                return false;
  46        if ((info->bitmask & EBT_IP_DEST) &&
  47           FWINV((ih->daddr & info->dmsk) !=
  48           info->daddr, EBT_IP_DEST))
  49                return false;
  50        if (info->bitmask & EBT_IP_PROTO) {
  51                if (FWINV(info->protocol != ih->protocol, EBT_IP_PROTO))
  52                        return false;
  53                if (!(info->bitmask & EBT_IP_DPORT) &&
  54                    !(info->bitmask & EBT_IP_SPORT))
  55                        return true;
  56                if (ntohs(ih->frag_off) & IP_OFFSET)
  57                        return false;
  58                pptr = skb_header_pointer(skb, ih->ihl*4,
  59                                          sizeof(_ports), &_ports);
  60                if (pptr == NULL)
  61                        return false;
  62                if (info->bitmask & EBT_IP_DPORT) {
  63                        u32 dst = ntohs(pptr->dst);
  64                        if (FWINV(dst < info->dport[0] ||
  65                                  dst > info->dport[1],
  66                                  EBT_IP_DPORT))
  67                        return false;
  68                }
  69                if (info->bitmask & EBT_IP_SPORT) {
  70                        u32 src = ntohs(pptr->src);
  71                        if (FWINV(src < info->sport[0] ||
  72                                  src > info->sport[1],
  73                                  EBT_IP_SPORT))
  74                        return false;
  75                }
  76        }
  77        return true;
  78}
  79
  80static bool ebt_ip_mt_check(const struct xt_mtchk_param *par)
  81{
  82        const struct ebt_ip_info *info = par->matchinfo;
  83        const struct ebt_entry *e = par->entryinfo;
  84
  85        if (e->ethproto != htons(ETH_P_IP) ||
  86           e->invflags & EBT_IPROTO)
  87                return false;
  88        if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
  89                return false;
  90        if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
  91                if (info->invflags & EBT_IP_PROTO)
  92                        return false;
  93                if (info->protocol != IPPROTO_TCP &&
  94                    info->protocol != IPPROTO_UDP &&
  95                    info->protocol != IPPROTO_UDPLITE &&
  96                    info->protocol != IPPROTO_SCTP &&
  97                    info->protocol != IPPROTO_DCCP)
  98                         return false;
  99        }
 100        if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
 101                return false;
 102        if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
 103                return false;
 104        return true;
 105}
 106
 107static struct xt_match ebt_ip_mt_reg __read_mostly = {
 108        .name           = "ip",
 109        .revision       = 0,
 110        .family         = NFPROTO_BRIDGE,
 111        .match          = ebt_ip_mt,
 112        .checkentry     = ebt_ip_mt_check,
 113        .matchsize      = XT_ALIGN(sizeof(struct ebt_ip_info)),
 114        .me             = THIS_MODULE,
 115};
 116
 117static int __init ebt_ip_init(void)
 118{
 119        return xt_register_match(&ebt_ip_mt_reg);
 120}
 121
 122static void __exit ebt_ip_fini(void)
 123{
 124        xt_unregister_match(&ebt_ip_mt_reg);
 125}
 126
 127module_init(ebt_ip_init);
 128module_exit(ebt_ip_fini);
 129MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
 130MODULE_LICENSE("GPL");
 131