diff options
Diffstat (limited to 'net/bridge/netfilter/ebt_arp.c')
| -rw-r--r-- | net/bridge/netfilter/ebt_arp.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_arp.c b/net/bridge/netfilter/ebt_arp.c new file mode 100644 index 00000000..cd457b89 --- /dev/null +++ b/net/bridge/netfilter/ebt_arp.c @@ -0,0 +1,140 @@ +/* + * 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, struct xt_action_param *par) +{ + const struct ebt_arp_info *info = par->matchinfo; + 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 int ebt_arp_mt_check(const struct xt_mtchk_param *par) +{ + const struct ebt_arp_info *info = par->matchinfo; + const struct ebt_entry *e = par->entryinfo; + + if ((e->ethproto != htons(ETH_P_ARP) && + e->ethproto != htons(ETH_P_RARP)) || + e->invflags & EBT_IPROTO) + return -EINVAL; + if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) + return -EINVAL; + return 0; +} + +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 = 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"); |