net/bridge/netfilter/ebt_ip.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  ebt_ip
   4  *
   5  *      Authors:
   6  *      Bart De Schuymer <bdschuym@pandora.be>
   7  *
   8  *  April, 2002
   9  *
  10  *  Changes:
  11  *    added ip-sport and ip-dport
  12  *    Innominate Security Technologies AG <mhopf@innominate.com>
  13  *    September, 2002
  14  */
  15 #include <linux/ip.h>
  16 #include <net/ip.h>
  17 #include <linux/in.h>
  18 #include <linux/module.h>
  19 #include <linux/netfilter/x_tables.h>
  20 #include <linux/netfilter_bridge/ebtables.h>
  21 #include <linux/netfilter_bridge/ebt_ip.h>
  22
  23 union pkthdr {
  24         struct {
  25                 __be16 src;
  26                 __be16 dst;
  27         } tcpudphdr;
  28         struct {
  29                 u8 type;
  30                 u8 code;
  31         } icmphdr;
  32         struct {
  33                 u8 type;
  34         } igmphdr;
  35 };
  36
  37 static bool
  38 ebt_ip_mt(const struct sk_buff *skb, struct xt_action_param *par)
  39 {
  40         const struct ebt_ip_info *info = par->matchinfo;
  41         const struct iphdr *ih;
  42         struct iphdr _iph;
  43         const union pkthdr *pptr;
  44         union pkthdr _pkthdr;
  45
  46         ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
  47         if (ih == NULL)
  48                 return false;
  49         if ((info->bitmask & EBT_IP_TOS) &&
  50             NF_INVF(info, EBT_IP_TOS, info->tos != ih->tos))
  51                 return false;
  52         if ((info->bitmask & EBT_IP_SOURCE) &&
  53             NF_INVF(info, EBT_IP_SOURCE,
  54                     (ih->saddr & info->smsk) != info->saddr))
  55                 return false;
  56         if ((info->bitmask & EBT_IP_DEST) &&
  57             NF_INVF(info, EBT_IP_DEST,
  58                     (ih->daddr & info->dmsk) != info->daddr))
  59                 return false;
  60         if (info->bitmask & EBT_IP_PROTO) {
  61                 if (NF_INVF(info, EBT_IP_PROTO, info->protocol != ih->protocol))
  62                         return false;
  63                 if (!(info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT |
  64                                        EBT_IP_ICMP | EBT_IP_IGMP)))
  65                         return true;
  66                 if (ntohs(ih->frag_off) & IP_OFFSET)
  67                         return false;
  68
  69                 /* min icmp/igmp headersize is 4, so sizeof(_pkthdr) is ok. */
  70                 pptr = skb_header_pointer(skb, ih->ihl*4,
  71                                           sizeof(_pkthdr), &_pkthdr);
  72                 if (pptr == NULL)
  73                         return false;
  74                 if (info->bitmask & EBT_IP_DPORT) {
  75                         u32 dst = ntohs(pptr->tcpudphdr.dst);
  76                         if (NF_INVF(info, EBT_IP_DPORT,
  77                                     dst < info->dport[0] ||
  78                                     dst > info->dport[1]))
  79                                 return false;
  80                 }
  81                 if (info->bitmask & EBT_IP_SPORT) {
  82                         u32 src = ntohs(pptr->tcpudphdr.src);
  83                         if (NF_INVF(info, EBT_IP_SPORT,
  84                                     src < info->sport[0] ||
  85                                     src > info->sport[1]))
  86                                 return false;
  87                 }
  88                 if ((info->bitmask & EBT_IP_ICMP) &&
  89                     NF_INVF(info, EBT_IP_ICMP,
  90                             pptr->icmphdr.type < info->icmp_type[0] ||
  91                             pptr->icmphdr.type > info->icmp_type[1] ||
  92                             pptr->icmphdr.code < info->icmp_code[0] ||
  93                             pptr->icmphdr.code > info->icmp_code[1]))
  94                         return false;
  95                 if ((info->bitmask & EBT_IP_IGMP) &&
  96                     NF_INVF(info, EBT_IP_IGMP,
  97                             pptr->igmphdr.type < info->igmp_type[0] ||
  98                             pptr->igmphdr.type > info->igmp_type[1]))
  99                         return false;
 100         }
 101         return true;
 102 }
 103
 104 static int ebt_ip_mt_check(const struct xt_mtchk_param *par)
 105 {
 106         const struct ebt_ip_info *info = par->matchinfo;
 107         const struct ebt_entry *e = par->entryinfo;
 108
 109         if (e->ethproto != htons(ETH_P_IP) ||
 110            e->invflags & EBT_IPROTO)
 111                 return -EINVAL;
 112         if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
 113                 return -EINVAL;
 114         if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
 115                 if (info->invflags & EBT_IP_PROTO)
 116                         return -EINVAL;
 117                 if (info->protocol != IPPROTO_TCP &&
 118                     info->protocol != IPPROTO_UDP &&
 119                     info->protocol != IPPROTO_UDPLITE &&
 120                     info->protocol != IPPROTO_SCTP &&
 121                     info->protocol != IPPROTO_DCCP)
 122                          return -EINVAL;
 123         }
 124         if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
 125                 return -EINVAL;
 126         if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
 127                 return -EINVAL;
 128         if (info->bitmask & EBT_IP_ICMP) {
 129                 if ((info->invflags & EBT_IP_PROTO) ||
 130                     info->protocol != IPPROTO_ICMP)
 131                         return -EINVAL;
 132                 if (info->icmp_type[0] > info->icmp_type[1] ||
 133                     info->icmp_code[0] > info->icmp_code[1])
 134                         return -EINVAL;
 135         }
 136         if (info->bitmask & EBT_IP_IGMP) {
 137                 if ((info->invflags & EBT_IP_PROTO) ||
 138                     info->protocol != IPPROTO_IGMP)
 139                         return -EINVAL;
 140                 if (info->igmp_type[0] > info->igmp_type[1])
 141                         return -EINVAL;
 142         }
 143         return 0;
 144 }
 145
 146 static struct xt_match ebt_ip_mt_reg __read_mostly = {
 147         .name           = "ip",
 148         .revision       = 0,
 149         .family         = NFPROTO_BRIDGE,
 150         .match          = ebt_ip_mt,
 151         .checkentry     = ebt_ip_mt_check,
 152         .matchsize      = sizeof(struct ebt_ip_info),
 153         .me             = THIS_MODULE,
 154 };
 155
 156 static int __init ebt_ip_init(void)
 157 {
 158         return xt_register_match(&ebt_ip_mt_reg);
 159 }
 160
 161 static void __exit ebt_ip_fini(void)
 162 {
 163         xt_unregister_match(&ebt_ip_mt_reg);
 164 }
 165
 166 module_init(ebt_ip_init);
 167 module_exit(ebt_ip_fini);
 168 MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
 169 MODULE_LICENSE("GPL");