| /* |
| * ebt_arp |
| * |
| * Authors: |
| * Bart De Schuymer <bdschuym@pandora.be> |
| * Tim Gardner <timg@tpi.com> |
| * |
| * April, 2002 |
| * |
| */ |
| #include <linux/if_arp.h> |
| #include <linux/if_ether.h> |
| #include <linux/module.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter_bridge/ebtables.h> |
| #include <linux/netfilter_bridge/ebt_arp.h> |
| |
| static bool |
| ebt_arp_mt(const struct sk_buff *skb, const struct net_device *in, |
| const struct net_device *out, const struct xt_match *match, |
| const void *data, int offset, unsigned int protoff, bool *hotdrop) |
| { |
| const struct ebt_arp_info *info = data; |
| const struct arphdr *ah; |
| struct arphdr _arph; |
| |
| ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); |
| if (ah == NULL) |
| return false; |
| if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != |
| ah->ar_op, EBT_ARP_OPCODE)) |
| return false; |
| if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != |
| ah->ar_hrd, EBT_ARP_HTYPE)) |
| return false; |
| if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != |
| ah->ar_pro, EBT_ARP_PTYPE)) |
| return false; |
| |
| if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP | EBT_ARP_GRAT)) { |
| const __be32 *sap, *dap; |
| __be32 saddr, daddr; |
| |
| if (ah->ar_pln != sizeof(__be32) || ah->ar_pro != htons(ETH_P_IP)) |
| return false; |
| sap = skb_header_pointer(skb, sizeof(struct arphdr) + |
| ah->ar_hln, sizeof(saddr), |
| &saddr); |
| if (sap == NULL) |
| return false; |
| dap = skb_header_pointer(skb, sizeof(struct arphdr) + |
| 2*ah->ar_hln+sizeof(saddr), |
| sizeof(daddr), &daddr); |
| if (dap == NULL) |
| return false; |
| if (info->bitmask & EBT_ARP_SRC_IP && |
| FWINV(info->saddr != (*sap & info->smsk), EBT_ARP_SRC_IP)) |
| return false; |
| if (info->bitmask & EBT_ARP_DST_IP && |
| FWINV(info->daddr != (*dap & info->dmsk), EBT_ARP_DST_IP)) |
| return false; |
| if (info->bitmask & EBT_ARP_GRAT && |
| FWINV(*dap != *sap, EBT_ARP_GRAT)) |
| return false; |
| } |
| |
| if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { |
| const unsigned char *mp; |
| unsigned char _mac[ETH_ALEN]; |
| uint8_t verdict, i; |
| |
| if (ah->ar_hln != ETH_ALEN || ah->ar_hrd != htons(ARPHRD_ETHER)) |
| return false; |
| if (info->bitmask & EBT_ARP_SRC_MAC) { |
| mp = skb_header_pointer(skb, sizeof(struct arphdr), |
| sizeof(_mac), &_mac); |
| if (mp == NULL) |
| return false; |
| verdict = 0; |
| for (i = 0; i < 6; i++) |
| verdict |= (mp[i] ^ info->smaddr[i]) & |
| info->smmsk[i]; |
| if (FWINV(verdict != 0, EBT_ARP_SRC_MAC)) |
| return false; |
| } |
| |
| if (info->bitmask & EBT_ARP_DST_MAC) { |
| mp = skb_header_pointer(skb, sizeof(struct arphdr) + |
| ah->ar_hln + ah->ar_pln, |
| sizeof(_mac), &_mac); |
| if (mp == NULL) |
| return false; |
| verdict = 0; |
| for (i = 0; i < 6; i++) |
| verdict |= (mp[i] ^ info->dmaddr[i]) & |
| info->dmmsk[i]; |
| if (FWINV(verdict != 0, EBT_ARP_DST_MAC)) |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| static bool |
| ebt_arp_mt_check(const char *table, const void *entry, |
| const struct xt_match *match, void *data, |
| unsigned int hook_mask) |
| { |
| const struct ebt_arp_info *info = data; |
| const struct ebt_entry *e = entry; |
| |
| if ((e->ethproto != htons(ETH_P_ARP) && |
| e->ethproto != htons(ETH_P_RARP)) || |
| e->invflags & EBT_IPROTO) |
| return false; |
| if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) |
| return false; |
| return true; |
| } |
| |
| static struct xt_match ebt_arp_mt_reg __read_mostly = { |
| .name = "arp", |
| .revision = 0, |
| .family = NFPROTO_BRIDGE, |
| .match = ebt_arp_mt, |
| .checkentry = ebt_arp_mt_check, |
| .matchsize = XT_ALIGN(sizeof(struct ebt_arp_info)), |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init ebt_arp_init(void) |
| { |
| return xt_register_match(&ebt_arp_mt_reg); |
| } |
| |
| static void __exit ebt_arp_fini(void) |
| { |
| xt_unregister_match(&ebt_arp_mt_reg); |
| } |
| |
| module_init(ebt_arp_init); |
| module_exit(ebt_arp_fini); |
| MODULE_DESCRIPTION("Ebtables: ARP protocol packet match"); |
| MODULE_LICENSE("GPL"); |