net: Get rid of IPv6 hash addresses flow keys

We don't need to return the IPv6 address hash as part of flow keys.
In general, using the IPv6 address hash is risky in a hash value
since the underlying use of xor provides no entropy. If someone
really needs the hash value they can get it from the full IPv6
addresses in flow keys (e.g. from flow_get_u32_src).

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow_dissector.h

@@ -103,7 +103,6 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
 	FLOW_DISSECTOR_KEY_IPV4_ADDRS, /* struct flow_dissector_key_ipv4_addrs */
 	FLOW_DISSECTOR_KEY_IPV6_ADDRS, /* struct flow_dissector_key_ipv6_addrs */
-	FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS, /* struct flow_dissector_key_addrs */
 	FLOW_DISSECTOR_KEY_PORTS, /* struct flow_dissector_key_ports */
 	FLOW_DISSECTOR_KEY_ETH_ADDRS, /* struct flow_dissector_key_eth_addrs */
 	FLOW_DISSECTOR_KEY_TIPC_ADDRS, /* struct flow_dissector_key_tipc_addrs */

net/core/flow_dissector.c

@@ -199,19 +199,6 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 		ip_proto = iph->nexthdr;
 		nhoff += sizeof(struct ipv6hdr);
 
-		if (skb_flow_dissector_uses_key(flow_dissector,
-						FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS)) {
-			key_addrs = skb_flow_dissector_target(flow_dissector,
-							      FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS,
-							      target_container);
-
-			key_addrs->v4addrs.src =
-				(__force __be32)ipv6_addr_hash(&iph->saddr);
-			key_addrs->v4addrs.dst =
-				(__force __be32)ipv6_addr_hash(&iph->daddr);
-			key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
-			goto flow_label;
-		}
 		if (skb_flow_dissector_uses_key(flow_dissector,
 						FLOW_DISSECTOR_KEY_IPV6_ADDRS)) {
 			struct flow_dissector_key_ipv6_addrs *key_ipv6_addrs;
@@ -650,10 +637,6 @@ static const struct flow_dissector_key flow_keys_dissector_keys[] = {
 		.key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS,
 		.offset = offsetof(struct flow_keys, addrs.v6addrs),
 	},
-	{
-		.key_id = FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS,
-		.offset = offsetof(struct flow_keys, addrs.v4addrs),
-	},
 	{
 		.key_id = FLOW_DISSECTOR_KEY_TIPC_ADDRS,
 		.offset = offsetof(struct flow_keys, addrs.tipcaddrs),