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 #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 bool
  28 ebt_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
  80 static bool
  81 ebt_ip_mt_check(const char *table, const void *entry,
  82                 const struct xt_match *match, void *data,
  83                 unsigned int hook_mask)
  84 {
  85         const struct ebt_ip_info *info = data;
  86         const struct ebt_entry *e = entry;
  87
  88         if (e->ethproto != htons(ETH_P_IP) ||
  89            e->invflags & EBT_IPROTO)
  90                 return false;
  91         if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
  92                 return false;
  93         if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
  94                 if (info->invflags & EBT_IP_PROTO)
  95                         return false;
  96                 if (info->protocol != IPPROTO_TCP &&
  97                     info->protocol != IPPROTO_UDP &&
  98                     info->protocol != IPPROTO_UDPLITE &&
  99                     info->protocol != IPPROTO_SCTP &&
 100                     info->protocol != IPPROTO_DCCP)
 101                          return false;
 102         }
 103         if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
 104                 return false;
 105         if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
 106                 return false;
 107         return true;
 108 }
 109
 110 static struct xt_match ebt_ip_mt_reg __read_mostly = {
 111         .name           = "ip",
 112         .revision       = 0,
 113         .family         = NFPROTO_BRIDGE,
 114         .match          = ebt_ip_mt,
 115         .checkentry     = ebt_ip_mt_check,
 116         .matchsize      = XT_ALIGN(sizeof(struct ebt_ip_info)),
 117         .me             = THIS_MODULE,
 118 };
 119
 120 static int __init ebt_ip_init(void)
 121 {
 122         return xt_register_match(&ebt_ip_mt_reg);
 123 }
 124
 125 static void __exit ebt_ip_fini(void)
 126 {
 127         xt_unregister_match(&ebt_ip_mt_reg);
 128 }
 129
 130 module_init(ebt_ip_init);
 131 module_exit(ebt_ip_fini);
 132 MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
 133 MODULE_LICENSE("GPL");