bonding: Do not tx-balance some IPv6 packets on ALB/TLB bonds

IPv6 all-node-multicasts and DAD probes should not be tx-balanced
on ALB/TLB bonds.  The all-node-multicast is an equivalent to IPv4
broadcasts.  DAD probes have to be sent only on the primary so that
we don't get false-positive detections.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/net/bonding/bond_alb.c

@@ -38,6 +38,7 @@
 #include <linux/in.h>
 #include <net/ipx.h>
 #include <net/arp.h>
+#include <net/ipv6.h>
 #include <asm/byteorder.h>
 #include "bonding.h"
 #include "bond_alb.h"
@@ -81,6 +82,7 @@
 #define RLB_PROMISC_TIMEOUT	10*ALB_TIMER_TICKS_PER_SEC
 
 static const u8 mac_bcast[ETH_ALEN] = {0xff,0xff,0xff,0xff,0xff,0xff};
+static const u8 mac_v6_allmcast[ETH_ALEN] = {0x33,0x33,0x00,0x00,0x00,0x01};
 static const int alb_delta_in_ticks = HZ / ALB_TIMER_TICKS_PER_SEC;
 
 #pragma pack(1)
@@ -1290,6 +1292,7 @@ int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 	u32 hash_index = 0;
 	const u8 *hash_start = NULL;
 	int res = 1;
+	struct ipv6hdr *ip6hdr;
 
 	skb_reset_mac_header(skb);
 	eth_data = eth_hdr(skb);
@@ -1319,11 +1322,32 @@ int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 	}
 		break;
 	case ETH_P_IPV6:
+		/* IPv6 doesn't really use broadcast mac address, but leave
+		 * that here just in case.
+		 */
 		if (memcmp(eth_data->h_dest, mac_bcast, ETH_ALEN) == 0) {
 			do_tx_balance = 0;
 			break;
 		}
 
+		/* IPv6 uses all-nodes multicast as an equivalent to
+		 * broadcasts in IPv4.
+		 */
+		if (memcmp(eth_data->h_dest, mac_v6_allmcast, ETH_ALEN) == 0) {
+			do_tx_balance = 0;
+			break;
+		}
+
+		/* Additianally, DAD probes should not be tx-balanced as that
+		 * will lead to false positives for duplicate addresses and
+		 * prevent address configuration from working.
+		 */
+		ip6hdr = ipv6_hdr(skb);
+		if (ipv6_addr_any(&ip6hdr->saddr)) {
+			do_tx_balance = 0;
+			break;
+		}
+
 		hash_start = (char *)&(ipv6_hdr(skb)->daddr);
 		hash_size = sizeof(ipv6_hdr(skb)->daddr);
 		break;