diff options
| author | Bart De Schuymer <bdschuym@pandora.be> | 2007-04-12 22:15:06 -0700 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:28:58 -0700 |
| commit | c15bf6e699f4c366f2d1e19ac5d7add21c6b5a19 (patch) | |
| tree | 2bcd680115a8b07cd6d7493b134ae2d36fe637be | |
| parent | 516299d2f5b6f9703b9b388faf91898dc636a678 (diff) | |
| download | linux-c15bf6e699f4c366f2d1e19ac5d7add21c6b5a19.tar.bz2 | |
[NETFILTER]: ebt_arp: add gratuitous arp filtering
The attached patch adds gratuitous arp filtering, more precisely: it
allows checking that the IPv4 source address matches the IPv4
destination address inside the ARP header. It also adds a check for the
hardware address type when matching MAC addresses (nothing critical,
just for better consistency).
Signed-off-by: Bart De Schuymer <bdschuym@pandora.be>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/netfilter_bridge/ebt_arp.h | 4 | ||||
| -rw-r--r-- | net/bridge/netfilter/ebt_arp.c | 48 |
2 files changed, 25 insertions, 27 deletions
diff --git a/include/linux/netfilter_bridge/ebt_arp.h b/include/linux/netfilter_bridge/ebt_arp.h index 97e4dbde1f89..cbf4843b6b0f 100644 --- a/include/linux/netfilter_bridge/ebt_arp.h +++ b/include/linux/netfilter_bridge/ebt_arp.h @@ -8,8 +8,10 @@ #define EBT_ARP_DST_IP 0x10 #define EBT_ARP_SRC_MAC 0x20 #define EBT_ARP_DST_MAC 0x40 +#define EBT_ARP_GRAT 0x80 #define EBT_ARP_MASK (EBT_ARP_OPCODE | EBT_ARP_HTYPE | EBT_ARP_PTYPE | \ - EBT_ARP_SRC_IP | EBT_ARP_DST_IP | EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC) + EBT_ARP_SRC_IP | EBT_ARP_DST_IP | EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC | \ + EBT_ARP_GRAT) #define EBT_ARP_MATCH "arp" struct ebt_arp_info diff --git a/net/bridge/netfilter/ebt_arp.c b/net/bridge/netfilter/ebt_arp.c index 9c599800a900..1a46952a56d9 100644 --- a/net/bridge/netfilter/ebt_arp.c +++ b/net/bridge/netfilter/ebt_arp.c @@ -35,40 +35,36 @@ static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in return EBT_NOMATCH; if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) { - __be32 _addr, *ap; + __be32 saddr, daddr, *sap, *dap; - /* IPv4 addresses are always 4 bytes */ - if (ah->ar_pln != sizeof(__be32)) + if (ah->ar_pln != sizeof(__be32) || ah->ar_pro != htons(ETH_P_IP)) + return EBT_NOMATCH; + sap = skb_header_pointer(skb, sizeof(struct arphdr) + + ah->ar_hln, sizeof(saddr), + &saddr); + if (sap == NULL) + return EBT_NOMATCH; + dap = skb_header_pointer(skb, sizeof(struct arphdr) + + 2*ah->ar_hln+sizeof(saddr), + sizeof(daddr), &daddr); + if (dap == NULL) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_SRC_IP && + FWINV(info->saddr != (*sap & info->smsk), EBT_ARP_SRC_IP)) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_DST_IP && + FWINV(info->daddr != (*dap & info->dmsk), EBT_ARP_DST_IP)) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_GRAT && + FWINV(*dap != *sap, EBT_ARP_GRAT)) return EBT_NOMATCH; - if (info->bitmask & EBT_ARP_SRC_IP) { - ap = skb_header_pointer(skb, sizeof(struct arphdr) + - ah->ar_hln, sizeof(_addr), - &_addr); - if (ap == NULL) - return EBT_NOMATCH; - if (FWINV(info->saddr != (*ap & info->smsk), - EBT_ARP_SRC_IP)) - return EBT_NOMATCH; - } - - if (info->bitmask & EBT_ARP_DST_IP) { - ap = skb_header_pointer(skb, sizeof(struct arphdr) + - 2*ah->ar_hln+sizeof(__be32), - sizeof(_addr), &_addr); - if (ap == NULL) - return EBT_NOMATCH; - if (FWINV(info->daddr != (*ap & info->dmsk), - EBT_ARP_DST_IP)) - return EBT_NOMATCH; - } } if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { unsigned char _mac[ETH_ALEN], *mp; uint8_t verdict, i; - /* MAC addresses are 6 bytes */ - if (ah->ar_hln != ETH_ALEN) + if (ah->ar_hln != ETH_ALEN || ah->ar_hrd != htons(ARPHRD_ETHER)) return EBT_NOMATCH; if (info->bitmask & EBT_ARP_SRC_MAC) { mp = skb_header_pointer(skb, sizeof(struct arphdr), |