| Message ID | 20170419194733.19006-1-linus.luessing@c0d3.blue |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
On Wed, Apr 19, 2017 at 09:47:33PM +0200, Linus Lüssing wrote: > When trying to redirect bridged frames to the bridge device itself or > a bridge port (brouting) via the dnat target then this currently fails: > > The ethernet destination of the frame is dnat'ed to the MAC address of > the bridge device or port just fine. However, the IP code drops it in > the beginning of ip_input.c/ip_rcv() as the dnat target left > the skb->pkt_type as PACKET_OTHERHOST. > > Fixing this by resetting skb->pkt_type to an appropriate type after > dnat'ing. Applied, thanks. One comment below. > @@ -18,11 +19,32 @@ static unsigned int > ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par) > { > const struct ebt_nat_info *info = par->targinfo; > + struct net_device *dev; > > if (!skb_make_writable(skb, 0)) > return EBT_DROP; > > ether_addr_copy(eth_hdr(skb)->h_dest, info->mac); > + > + if (is_multicast_ether_addr(info->mac)) { > + if (is_broadcast_ether_addr(info->mac)) > + skb->pkt_type = PACKET_BROADCAST; > + else > + skb->pkt_type = PACKET_MULTICAST; > + } else { > + rcu_read_lock(); I'm going to manually remove this explicit rcu_read_lock() here, no need to resend. We're guaranteed to run from packet path with read side lock from netfilter hooks. So we just save some cycles from running this unnecessary nesting. Let me know if I'm missing anything. Thanks! -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/bridge/netfilter/ebt_dnat.c b/net/bridge/netfilter/ebt_dnat.c index 4e0b0c3..21acb53 100644 --- a/net/bridge/netfilter/ebt_dnat.c +++ b/net/bridge/netfilter/ebt_dnat.c @@ -9,6 +9,7 @@ */ #include <linux/module.h> #include <net/sock.h> +#include "../br_private.h" #include <linux/netfilter.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_bridge/ebtables.h> @@ -18,11 +19,32 @@ static unsigned int ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par) { const struct ebt_nat_info *info = par->targinfo; + struct net_device *dev; if (!skb_make_writable(skb, 0)) return EBT_DROP; ether_addr_copy(eth_hdr(skb)->h_dest, info->mac); + + if (is_multicast_ether_addr(info->mac)) { + if (is_broadcast_ether_addr(info->mac)) + skb->pkt_type = PACKET_BROADCAST; + else + skb->pkt_type = PACKET_MULTICAST; + } else { + rcu_read_lock(); + if (xt_hooknum(par) != NF_BR_BROUTING) + dev = br_port_get_rcu(xt_in(par))->br->dev; + else + dev = xt_in(par); + + if (ether_addr_equal(info->mac, dev->dev_addr)) + skb->pkt_type = PACKET_HOST; + else + skb->pkt_type = PACKET_OTHERHOST; + rcu_read_unlock(); + } + return info->target; }
When trying to redirect bridged frames to the bridge device itself or a bridge port (brouting) via the dnat target then this currently fails: The ethernet destination of the frame is dnat'ed to the MAC address of the bridge device or port just fine. However, the IP code drops it in the beginning of ip_input.c/ip_rcv() as the dnat target left the skb->pkt_type as PACKET_OTHERHOST. Fixing this by resetting skb->pkt_type to an appropriate type after dnat'ing. Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> --- Changelog v3: - moved pkt_type fixup into ebtable dnat code -> v1/v2 only fixed it for prerouting/dnat so far, now tested and verified that v3 fixes it for brouting/dnat, too - updated commit message Changelog v2: - refrain from altering pkt_type for multicast packets with a unicast destination MAC --- net/bridge/netfilter/ebt_dnat.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)