net: bonding: Add support for IPV6 ns/na

Since ipv6 neighbor solicitation and advertisement messages
isn't handled gracefully in bonding6 driver, we can see packet
drop due to inconsistency bewteen mac address in the option
message and source MAC .

Another examples is ipv6 neighbor solicitation and advertisement
messages from VM via tap attached to host brighe, the src mac
mighe be changed through balance-alb mode, but it is not synced
with Link-layer address in the option message.

The patch implements bond6's tx handle for ipv6 neighbor
solicitation and advertisement messages.

			Border-Leaf
			/        \
		       /          \
		    Tunnel1    Tunnel2
		     /              \
	            /                \
		  Leaf-1--Tunnel3--Leaf-2
		    \                /
		     \              /
		      \            /
		       \          /
		       NIC1    NIC2
			\      /
			server

We can see in our lab the Border-Leaf receives occasionally
a NA packet which is assigned to NIC1 mac in ND/NS option
message, but actaully send out via NIC2 mac due to tx-alb,
as a result, it will cause inconsistency between MAC table
and ND Table in Border-Leaf, i.e, NIC1 = Tunnel2 in ND table
and  NIC1 = Tunnel1 in mac table.

And then, Border-Leaf starts to forward packet destinated
to the Server, it will only check the ND table entry in some
switch to encapsulate the destination MAC of the message as
NIC1 MAC, and then send it out from Tunnel2 by ND table.
Then, Leaf-2 receives the packet, it notices the destination
MAC of message is NIC1 MAC and should forword it to Tunne1
by Tunnel3.

However, this traffic forward will be failure due to split
horizon of VxLAN tunnels.

Suggested-by: Hu Yadi <huyd12@chinatelecom.cn>
Signed-off-by: Sun Shouxin <sunshouxin@chinatelecom.cn>

drivers/net/bonding/bond_alb.c

@@ -22,6 +22,7 @@
 #include <asm/byteorder.h>
 #include <net/bonding.h>
 #include <net/bond_alb.h>
+#include <net/ndisc.h>
 
 static const u8 mac_v6_allmcast[ETH_ALEN + 2] __long_aligned = {
 	0x33, 0x33, 0x00, 0x00, 0x00, 0x01
@@ -1269,6 +1270,119 @@ static int alb_set_mac_address(struct bonding *bond, void *addr)
 	return res;
 }
 
+/*determine if the packet is NA or NS*/
+static bool alb_determine_nd(struct icmp6hdr *hdr)
+{
+	if (hdr->icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT ||
+	    hdr->icmp6_type == NDISC_NEIGHBOUR_SOLICITATION) {
+		return true;
+	}
+
+	return false;
+}
+
+static void alb_change_nd_option(struct sk_buff *skb, void *data)
+{
+	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
+	struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)msg->opt;
+	struct net_device *dev = skb->dev;
+	struct icmp6hdr *icmp6h = icmp6_hdr(skb);
+	struct ipv6hdr *ip6hdr = ipv6_hdr(skb);
+	u8 *lladdr = NULL;
+	u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +
+				offsetof(struct nd_msg, opt));
+
+	while (ndoptlen) {
+		int l;
+
+		switch (nd_opt->nd_opt_type) {
+		case ND_OPT_SOURCE_LL_ADDR:
+		case ND_OPT_TARGET_LL_ADDR:
+		lladdr = ndisc_opt_addr_data(nd_opt, dev);
+		break;
+
+		default:
+		lladdr = NULL;
+		break;
+		}
+
+		l = nd_opt->nd_opt_len << 3;
+
+		if (ndoptlen < l || l == 0)
+			return;
+
+		if (lladdr) {
+			memcpy(lladdr, data, dev->addr_len);
+			icmp6h->icmp6_cksum = 0;
+
+			icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6hdr->saddr,
+							      &ip6hdr->daddr,
+						ntohs(ip6hdr->payload_len),
+						IPPROTO_ICMPV6,
+						csum_partial(icmp6h,
+							     ntohs(ip6hdr->payload_len), 0));
+		}
+		ndoptlen -= l;
+		nd_opt = ((void *)nd_opt) + l;
+	}
+}
+
+static u8 *alb_get_lladdr(struct sk_buff *skb)
+{
+	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
+	struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)msg->opt;
+	struct net_device *dev = skb->dev;
+	u8 *lladdr = NULL;
+	u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +
+				offsetof(struct nd_msg, opt));
+
+	while (ndoptlen) {
+		int l;
+
+		switch (nd_opt->nd_opt_type) {
+		case ND_OPT_SOURCE_LL_ADDR:
+		case ND_OPT_TARGET_LL_ADDR:
+			lladdr = ndisc_opt_addr_data(nd_opt, dev);
+			break;
+
+		default:
+			break;
+		}
+
+		l = nd_opt->nd_opt_len << 3;
+
+		if (ndoptlen < l || l == 0)
+			return lladdr;
+
+		if (lladdr)
+			return lladdr;
+
+		ndoptlen -= l;
+		nd_opt = ((void *)nd_opt) + l;
+	}
+
+	return lladdr;
+}
+
+static void alb_set_nd_option(struct sk_buff *skb, struct bonding *bond,
+			      struct slave *tx_slave)
+{
+	struct ipv6hdr *ip6hdr;
+	struct icmp6hdr *hdr = NULL;
+
+	if (skb->protocol == htons(ETH_P_IPV6)) {
+		if (tx_slave && tx_slave !=
+		    rcu_access_pointer(bond->curr_active_slave)) {
+			ip6hdr = ipv6_hdr(skb);
+			if (ip6hdr->nexthdr == IPPROTO_ICMPV6) {
+				hdr = icmp6_hdr(skb);
+				if (alb_determine_nd(hdr))
+					alb_change_nd_option(skb, tx_slave->dev->dev_addr);
+			}
+		}
+	}
+}
+
 /************************ exported alb functions ************************/
 
 int bond_alb_initialize(struct bonding *bond, int rlb_enabled)
@@ -1415,6 +1529,7 @@ struct slave *bond_xmit_alb_slave_get(struct bonding *bond,
 	}
 	case ETH_P_IPV6: {
 		const struct ipv6hdr *ip6hdr;
+		struct icmp6hdr *hdr = NULL;
 
 		/* IPv6 doesn't really use broadcast mac address, but leave
 		 * that here just in case.
@@ -1446,6 +1561,21 @@ struct slave *bond_xmit_alb_slave_get(struct bonding *bond,
 			break;
 		}
 
+		if (ip6hdr->nexthdr == IPPROTO_ICMPV6) {
+			hdr = icmp6_hdr(skb);
+			if (alb_determine_nd(hdr)) {
+				u8 *lladdr = NULL;
+
+				lladdr = alb_get_lladdr(skb);
+				if (lladdr) {
+					if (!bond_slave_has_mac_rx(bond, lladdr)) {
+						do_tx_balance = false;
+						break;
+					}
+				}
+			}
+		}
+
 		hash_start = (char *)&ip6hdr->daddr;
 		hash_size = sizeof(ip6hdr->daddr);
 		break;
@@ -1489,6 +1619,7 @@ netdev_tx_t bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 	struct slave *tx_slave = NULL;
 
 	tx_slave = bond_xmit_alb_slave_get(bond, skb);
+	alb_set_nd_option(skb, bond, tx_slave);
 	return bond_do_alb_xmit(skb, bond, tx_slave);
 }