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   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
  22 struct tcpudphdr {
  23         __be16 src;
  24         __be16 dst;
  25 };
  26
  27 static int ebt_filter_ip(const struct sk_buff *skb, const struct net_device *in,
  28    const struct net_device *out, const void *data,
  29    unsigned int datalen)
  30 {
  31         const struct ebt_ip_info *info = data;
  32         const struct iphdr *ih;
  33         struct iphdr _iph;
  34         const struct tcpudphdr *pptr;
  35         struct tcpudphdr _ports;
  36
  37         ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
  38         if (ih == NULL)
  39                 return EBT_NOMATCH;
  40         if (info->bitmask & EBT_IP_TOS &&
  41            FWINV(info->tos != ih->tos, EBT_IP_TOS))
  42                 return EBT_NOMATCH;
  43         if (info->bitmask & EBT_IP_SOURCE &&
  44            FWINV((ih->saddr & info->smsk) !=
  45            info->saddr, EBT_IP_SOURCE))
  46                 return EBT_NOMATCH;
  47         if ((info->bitmask & EBT_IP_DEST) &&
  48            FWINV((ih->daddr & info->dmsk) !=
  49            info->daddr, EBT_IP_DEST))
  50                 return EBT_NOMATCH;
  51         if (info->bitmask & EBT_IP_PROTO) {
  52                 if (FWINV(info->protocol != ih->protocol, EBT_IP_PROTO))
  53                         return EBT_NOMATCH;
  54                 if (!(info->bitmask & EBT_IP_DPORT) &&
  55                     !(info->bitmask & EBT_IP_SPORT))
  56                         return EBT_MATCH;
  57                 if (ntohs(ih->frag_off) & IP_OFFSET)
  58                         return EBT_NOMATCH;
  59                 pptr = skb_header_pointer(skb, ih->ihl*4,
  60                                           sizeof(_ports), &_ports);
  61                 if (pptr == NULL)
  62                         return EBT_NOMATCH;
  63                 if (info->bitmask & EBT_IP_DPORT) {
  64                         u32 dst = ntohs(pptr->dst);
  65                         if (FWINV(dst < info->dport[0] ||
  66                                   dst > info->dport[1],
  67                                   EBT_IP_DPORT))
  68                         return EBT_NOMATCH;
  69                 }
  70                 if (info->bitmask & EBT_IP_SPORT) {
  71                         u32 src = ntohs(pptr->src);
  72                         if (FWINV(src < info->sport[0] ||
  73                                   src > info->sport[1],
  74                                   EBT_IP_SPORT))
  75                         return EBT_NOMATCH;
  76                 }
  77         }
  78         return EBT_MATCH;
  79 }
  80
  81 static int ebt_ip_check(const char *tablename, unsigned int hookmask,
  82    const struct ebt_entry *e, void *data, unsigned int datalen)
  83 {
  84         const struct ebt_ip_info *info = data;
  85
  86         if (e->ethproto != htons(ETH_P_IP) ||
  87            e->invflags & EBT_IPROTO)
  88                 return -EINVAL;
  89         if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
  90                 return -EINVAL;
  91         if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
  92                 if (info->invflags & EBT_IP_PROTO)
  93                         return -EINVAL;
  94                 if (info->protocol != IPPROTO_TCP &&
  95                     info->protocol != IPPROTO_UDP &&
  96                     info->protocol != IPPROTO_UDPLITE &&
  97                     info->protocol != IPPROTO_SCTP &&
  98                     info->protocol != IPPROTO_DCCP)
  99                          return -EINVAL;
 100         }
 101         if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
 102                 return -EINVAL;
 103         if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
 104                 return -EINVAL;
 105         return 0;
 106 }
 107
 108 static struct ebt_match filter_ip __read_mostly = {
 109         .name           = EBT_IP_MATCH,
 110         .match          = ebt_filter_ip,
 111         .check          = ebt_ip_check,
 112         .matchsize      = XT_ALIGN(sizeof(struct ebt_ip_info)),
 113         .me             = THIS_MODULE,
 114 };
 115
 116 static int __init ebt_ip_init(void)
 117 {
 118         return ebt_register_match(&filter_ip);
 119 }
 120
 121 static void __exit ebt_ip_fini(void)
 122 {
 123         ebt_unregister_match(&filter_ip);
 124 }
 125
 126 module_init(ebt_ip_init);
 127 module_exit(ebt_ip_fini);
 128 MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
 129 MODULE_LICENSE("GPL");