net/bridge/netfilter/ebt_ip.c

   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
  15 #include <linux/netfilter_bridge/ebtables.h>
  16 #include <linux/netfilter_bridge/ebt_ip.h>
  17 #include <linux/ip.h>
  18 #include <net/ip.h>
  19 #include <linux/in.h>
  20 #include <linux/module.h>
  21
  22 struct tcpudphdr {
  23         uint16_t src;
  24         uint16_t 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         struct ebt_ip_info *info = (struct ebt_ip_info *)data;
  32         struct iphdr _iph, *ih;
  33         struct tcpudphdr _ports, *pptr;
  34
  35         ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
  36         if (ih == NULL)
  37                 return EBT_NOMATCH;
  38         if (info->bitmask & EBT_IP_TOS &&
  39            FWINV(info->tos != ih->tos, EBT_IP_TOS))
  40                 return EBT_NOMATCH;
  41         if (info->bitmask & EBT_IP_SOURCE &&
  42            FWINV((ih->saddr & info->smsk) !=
  43            info->saddr, EBT_IP_SOURCE))
  44                 return EBT_NOMATCH;
  45         if ((info->bitmask & EBT_IP_DEST) &&
  46            FWINV((ih->daddr & info->dmsk) !=
  47            info->daddr, EBT_IP_DEST))
  48                 return EBT_NOMATCH;
  49         if (info->bitmask & EBT_IP_PROTO) {
  50                 if (FWINV(info->protocol != ih->protocol, EBT_IP_PROTO))
  51                         return EBT_NOMATCH;
  52                 if (!(info->bitmask & EBT_IP_DPORT) &&
  53                     !(info->bitmask & EBT_IP_SPORT))
  54                         return EBT_MATCH;
  55                 if (ntohs(ih->frag_off) & IP_OFFSET)
  56                         return EBT_NOMATCH;
  57                 pptr = skb_header_pointer(skb, ih->ihl*4,
  58                                           sizeof(_ports), &_ports);
  59                 if (pptr == NULL)
  60                         return EBT_NOMATCH;
  61                 if (info->bitmask & EBT_IP_DPORT) {
  62                         u32 dst = ntohs(pptr->dst);
  63                         if (FWINV(dst < info->dport[0] ||
  64                                   dst > info->dport[1],
  65                                   EBT_IP_DPORT))
  66                         return EBT_NOMATCH;
  67                 }
  68                 if (info->bitmask & EBT_IP_SPORT) {
  69                         u32 src = ntohs(pptr->src);
  70                         if (FWINV(src < info->sport[0] ||
  71                                   src > info->sport[1],
  72                                   EBT_IP_SPORT))
  73                         return EBT_NOMATCH;
  74                 }
  75         }
  76         return EBT_MATCH;
  77 }
  78
  79 static int ebt_ip_check(const char *tablename, unsigned int hookmask,
  80    const struct ebt_entry *e, void *data, unsigned int datalen)
  81 {
  82         struct ebt_ip_info *info = (struct ebt_ip_info *)data;
  83
  84         if (datalen != EBT_ALIGN(sizeof(struct ebt_ip_info)))
  85                 return -EINVAL;
  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_SCTP &&
  97                     info->protocol != IPPROTO_DCCP)
  98                          return -EINVAL;
  99         }
 100         if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
 101                 return -EINVAL;
 102         if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
 103                 return -EINVAL;
 104         return 0;
 105 }
 106
 107 static struct ebt_match filter_ip =
 108 {
 109         .name           = EBT_IP_MATCH,
 110         .match          = ebt_filter_ip,
 111         .check          = ebt_ip_check,
 112         .me             = THIS_MODULE,
 113 };
 114
 115 static int __init ebt_ip_init(void)
 116 {
 117         return ebt_register_match(&filter_ip);
 118 }
 119
 120 static void __exit ebt_ip_fini(void)
 121 {
 122         ebt_unregister_match(&filter_ip);
 123 }
 124
 125 module_init(ebt_ip_init);
 126 module_exit(ebt_ip_fini);
 127 MODULE_LICENSE("GPL");