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 union pkthdr {
  23         struct {
  24                 __be16 src;
  25                 __be16 dst;
  26         } tcpudphdr;
  27         struct {
  28                 u8 type;
  29                 u8 code;
  30         } icmphdr;
  31         struct {
  32                 u8 type;
  33         } igmphdr;
  34 };
  35
  36 static bool
  37 ebt_ip_mt(const struct sk_buff *skb, struct xt_action_param *par)
  38 {
  39         const struct ebt_ip_info *info = par->matchinfo;
  40         const struct iphdr *ih;
  41         struct iphdr _iph;
  42         const union pkthdr *pptr;
  43         union pkthdr _pkthdr;
  44
  45         ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
  46         if (ih == NULL)
  47                 return false;
  48         if ((info->bitmask & EBT_IP_TOS) &&
  49             NF_INVF(info, EBT_IP_TOS, info->tos != ih->tos))
  50                 return false;
  51         if ((info->bitmask & EBT_IP_SOURCE) &&
  52             NF_INVF(info, EBT_IP_SOURCE,
  53                     (ih->saddr & info->smsk) != info->saddr))
  54                 return false;
  55         if ((info->bitmask & EBT_IP_DEST) &&
  56             NF_INVF(info, EBT_IP_DEST,
  57                     (ih->daddr & info->dmsk) != info->daddr))
  58                 return false;
  59         if (info->bitmask & EBT_IP_PROTO) {
  60                 if (NF_INVF(info, EBT_IP_PROTO, info->protocol != ih->protocol))
  61                         return false;
  62                 if (!(info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT |
  63                                        EBT_IP_ICMP | EBT_IP_IGMP)))
  64                         return true;
  65                 if (ntohs(ih->frag_off) & IP_OFFSET)
  66                         return false;
  67
  68                 /* min icmp/igmp headersize is 4, so sizeof(_pkthdr) is ok. */
  69                 pptr = skb_header_pointer(skb, ih->ihl*4,
  70                                           sizeof(_pkthdr), &_pkthdr);
  71                 if (pptr == NULL)
  72                         return false;
  73                 if (info->bitmask & EBT_IP_DPORT) {
  74                         u32 dst = ntohs(pptr->tcpudphdr.dst);
  75                         if (NF_INVF(info, EBT_IP_DPORT,
  76                                     dst < info->dport[0] ||
  77                                     dst > info->dport[1]))
  78                                 return false;
  79                 }
  80                 if (info->bitmask & EBT_IP_SPORT) {
  81                         u32 src = ntohs(pptr->tcpudphdr.src);
  82                         if (NF_INVF(info, EBT_IP_SPORT,
  83                                     src < info->sport[0] ||
  84                                     src > info->sport[1]))
  85                                 return false;
  86                 }
  87                 if ((info->bitmask & EBT_IP_ICMP) &&
  88                     NF_INVF(info, EBT_IP_ICMP,
  89                             pptr->icmphdr.type < info->icmp_type[0] ||
  90                             pptr->icmphdr.type > info->icmp_type[1] ||
  91                             pptr->icmphdr.code < info->icmp_code[0] ||
  92                             pptr->icmphdr.code > info->icmp_code[1]))
  93                         return false;
  94                 if ((info->bitmask & EBT_IP_IGMP) &&
  95                     NF_INVF(info, EBT_IP_IGMP,
  96                             pptr->igmphdr.type < info->igmp_type[0] ||
  97                             pptr->igmphdr.type > info->igmp_type[1]))
  98                         return false;
  99         }
 100         return true;
 101 }
 102
 103 static int ebt_ip_mt_check(const struct xt_mtchk_param *par)
 104 {
 105         const struct ebt_ip_info *info = par->matchinfo;
 106         const struct ebt_entry *e = par->entryinfo;
 107
 108         if (e->ethproto != htons(ETH_P_IP) ||
 109            e->invflags & EBT_IPROTO)
 110                 return -EINVAL;
 111         if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
 112                 return -EINVAL;
 113         if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
 114                 if (info->invflags & EBT_IP_PROTO)
 115                         return -EINVAL;
 116                 if (info->protocol != IPPROTO_TCP &&
 117                     info->protocol != IPPROTO_UDP &&
 118                     info->protocol != IPPROTO_UDPLITE &&
 119                     info->protocol != IPPROTO_SCTP &&
 120                     info->protocol != IPPROTO_DCCP)
 121                          return -EINVAL;
 122         }
 123         if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
 124                 return -EINVAL;
 125         if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
 126                 return -EINVAL;
 127         if (info->bitmask & EBT_IP_ICMP) {
 128                 if ((info->invflags & EBT_IP_PROTO) ||
 129                     info->protocol != IPPROTO_ICMP)
 130                         return -EINVAL;
 131                 if (info->icmp_type[0] > info->icmp_type[1] ||
 132                     info->icmp_code[0] > info->icmp_code[1])
 133                         return -EINVAL;
 134         }
 135         if (info->bitmask & EBT_IP_IGMP) {
 136                 if ((info->invflags & EBT_IP_PROTO) ||
 137                     info->protocol != IPPROTO_IGMP)
 138                         return -EINVAL;
 139                 if (info->igmp_type[0] > info->igmp_type[1])
 140                         return -EINVAL;
 141         }
 142         return 0;
 143 }
 144
 145 static struct xt_match ebt_ip_mt_reg __read_mostly = {
 146         .name           = "ip",
 147         .revision       = 0,
 148         .family         = NFPROTO_BRIDGE,
 149         .match          = ebt_ip_mt,
 150         .checkentry     = ebt_ip_mt_check,
 151         .matchsize      = sizeof(struct ebt_ip_info),
 152         .me             = THIS_MODULE,
 153 };
 154
 155 static int __init ebt_ip_init(void)
 156 {
 157         return xt_register_match(&ebt_ip_mt_reg);
 158 }
 159
 160 static void __exit ebt_ip_fini(void)
 161 {
 162         xt_unregister_match(&ebt_ip_mt_reg);
 163 }
 164
 165 module_init(ebt_ip_init);
 166 module_exit(ebt_ip_fini);
 167 MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
 168 MODULE_LICENSE("GPL");