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   1 /*
   2  *  ebt_ip6
   3  *
   4  *      Authors:
   5  *      Manohar Castelino <manohar.r.castelino@intel.com>
   6  *      Kuo-Lang Tseng <kuo-lang.tseng@intel.com>
   7  *      Jan Engelhardt <jengelh@computergmbh.de>
   8  *
   9  * Summary:
  10  * This is just a modification of the IPv4 code written by
  11  * Bart De Schuymer <bdschuym@pandora.be>
  12  * with the changes required to support IPv6
  13  *
  14  *  Jan, 2008
  15  */
  16 #include <linux/ipv6.h>
  17 #include <net/ipv6.h>
  18 #include <linux/in.h>
  19 #include <linux/module.h>
  20 #include <net/dsfield.h>
  21 #include <linux/netfilter/x_tables.h>
  22 #include <linux/netfilter_bridge/ebtables.h>
  23 #include <linux/netfilter_bridge/ebt_ip6.h>
  24
  25 struct tcpudphdr {
  26         __be16 src;
  27         __be16 dst;
  28 };
  29
  30 static bool
  31 ebt_ip6_mt(const struct sk_buff *skb, const struct net_device *in,
  32            const struct net_device *out, const struct xt_match *match,
  33            const void *data, int offset, unsigned int protoff, bool *hotdrop)
  34 {
  35         const struct ebt_ip6_info *info = (struct ebt_ip6_info *)data;
  36         const struct ipv6hdr *ih6;
  37         struct ipv6hdr _ip6h;
  38         const struct tcpudphdr *pptr;
  39         struct tcpudphdr _ports;
  40         struct in6_addr tmp_addr;
  41         int i;
  42
  43         ih6 = skb_header_pointer(skb, 0, sizeof(_ip6h), &_ip6h);
  44         if (ih6 == NULL)
  45                 return false;
  46         if (info->bitmask & EBT_IP6_TCLASS &&
  47            FWINV(info->tclass != ipv6_get_dsfield(ih6), EBT_IP6_TCLASS))
  48                 return false;
  49         for (i = 0; i < 4; i++)
  50                 tmp_addr.in6_u.u6_addr32[i] = ih6->saddr.in6_u.u6_addr32[i] &
  51                         info->smsk.in6_u.u6_addr32[i];
  52         if (info->bitmask & EBT_IP6_SOURCE &&
  53                 FWINV((ipv6_addr_cmp(&tmp_addr, &info->saddr) != 0),
  54                         EBT_IP6_SOURCE))
  55                 return false;
  56         for (i = 0; i < 4; i++)
  57                 tmp_addr.in6_u.u6_addr32[i] = ih6->daddr.in6_u.u6_addr32[i] &
  58                         info->dmsk.in6_u.u6_addr32[i];
  59         if (info->bitmask & EBT_IP6_DEST &&
  60            FWINV((ipv6_addr_cmp(&tmp_addr, &info->daddr) != 0), EBT_IP6_DEST))
  61                 return false;
  62         if (info->bitmask & EBT_IP6_PROTO) {
  63                 uint8_t nexthdr = ih6->nexthdr;
  64                 int offset_ph;
  65
  66                 offset_ph = ipv6_skip_exthdr(skb, sizeof(_ip6h), &nexthdr);
  67                 if (offset_ph == -1)
  68                         return false;
  69                 if (FWINV(info->protocol != nexthdr, EBT_IP6_PROTO))
  70                         return false;
  71                 if (!(info->bitmask & EBT_IP6_DPORT) &&
  72                     !(info->bitmask & EBT_IP6_SPORT))
  73                         return true;
  74                 pptr = skb_header_pointer(skb, offset_ph, sizeof(_ports),
  75                                           &_ports);
  76                 if (pptr == NULL)
  77                         return false;
  78                 if (info->bitmask & EBT_IP6_DPORT) {
  79                         u32 dst = ntohs(pptr->dst);
  80                         if (FWINV(dst < info->dport[0] ||
  81                                   dst > info->dport[1], EBT_IP6_DPORT))
  82                                 return false;
  83                 }
  84                 if (info->bitmask & EBT_IP6_SPORT) {
  85                         u32 src = ntohs(pptr->src);
  86                         if (FWINV(src < info->sport[0] ||
  87                                   src > info->sport[1], EBT_IP6_SPORT))
  88                         return false;
  89                 }
  90                 return true;
  91         }
  92         return true;
  93 }
  94
  95 static bool
  96 ebt_ip6_mt_check(const char *table, const void *entry,
  97                  const struct xt_match *match, void *data,
  98                  unsigned int hook_mask)
  99 {
 100         const struct ebt_entry *e = entry;
 101         struct ebt_ip6_info *info = (struct ebt_ip6_info *)data;
 102
 103         if (e->ethproto != htons(ETH_P_IPV6) || e->invflags & EBT_IPROTO)
 104                 return false;
 105         if (info->bitmask & ~EBT_IP6_MASK || info->invflags & ~EBT_IP6_MASK)
 106                 return false;
 107         if (info->bitmask & (EBT_IP6_DPORT | EBT_IP6_SPORT)) {
 108                 if (info->invflags & EBT_IP6_PROTO)
 109                         return false;
 110                 if (info->protocol != IPPROTO_TCP &&
 111                     info->protocol != IPPROTO_UDP &&
 112                     info->protocol != IPPROTO_UDPLITE &&
 113                     info->protocol != IPPROTO_SCTP &&
 114                     info->protocol != IPPROTO_DCCP)
 115                         return false;
 116         }
 117         if (info->bitmask & EBT_IP6_DPORT && info->dport[0] > info->dport[1])
 118                 return false;
 119         if (info->bitmask & EBT_IP6_SPORT && info->sport[0] > info->sport[1])
 120                 return false;
 121         return true;
 122 }
 123
 124 static struct ebt_match filter_ip6 =
 125 {
 126         .name           = EBT_IP6_MATCH,
 127         .revision       = 0,
 128         .family         = NFPROTO_BRIDGE,
 129         .match          = ebt_ip6_mt,
 130         .checkentry     = ebt_ip6_mt_check,
 131         .matchsize      = XT_ALIGN(sizeof(struct ebt_ip6_info)),
 132         .me             = THIS_MODULE,
 133 };
 134
 135 static int __init ebt_ip6_init(void)
 136 {
 137         return ebt_register_match(&filter_ip6);
 138 }
 139
 140 static void __exit ebt_ip6_fini(void)
 141 {
 142         ebt_unregister_match(&filter_ip6);
 143 }
 144
 145 module_init(ebt_ip6_init);
 146 module_exit(ebt_ip6_fini);
 147 MODULE_DESCRIPTION("Ebtables: IPv6 protocol packet match");
 148 MODULE_LICENSE("GPL");