mlx4: use netdev_rss_key_fill() helper

Use of well known RSS key increases attack surface.
Switch to a random one, using generic helper so that all
ports share a common key.

Also provide ethtool -x support to fetch RSS key

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_ethtool.c

@@ -973,6 +973,11 @@ static u32 mlx4_en_get_rxfh_indir_size(struct net_device *dev)
 	return priv->rx_ring_num;
 }
 
+static u32 mlx4_en_get_rxfh_key_size(struct net_device *netdev)
+{
+	return MLX4_EN_RSS_KEY_SIZE;
+}
+
 static int mlx4_en_get_rxfh(struct net_device *dev, u32 *ring_index, u8 *key)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
@@ -988,7 +993,8 @@ static int mlx4_en_get_rxfh(struct net_device *dev, u32 *ring_index, u8 *key)
 		ring_index[n] = rss_map->qps[n % rss_rings].qpn -
 			rss_map->base_qpn;
 	}
-
+	if (key)
+		netdev_rss_key_fill(key, MLX4_EN_RSS_KEY_SIZE);
 	return err;
 }
 
@@ -1799,6 +1805,7 @@ const struct ethtool_ops mlx4_en_ethtool_ops = {
 	.get_rxnfc = mlx4_en_get_rxnfc,
 	.set_rxnfc = mlx4_en_set_rxnfc,
 	.get_rxfh_indir_size = mlx4_en_get_rxfh_indir_size,
+	.get_rxfh_key_size = mlx4_en_get_rxfh_key_size,
 	.get_rxfh = mlx4_en_get_rxfh,
 	.set_rxfh = mlx4_en_set_rxfh,
 	.get_channels = mlx4_en_get_channels,

drivers/net/ethernet/mellanox/mlx4/en_rx.c

@@ -1169,9 +1169,6 @@ int mlx4_en_config_rss_steer(struct mlx4_en_priv *priv)
 	int i, qpn;
 	int err = 0;
 	int good_qps = 0;
-	static const u32 rsskey[10] = { 0xD181C62C, 0xF7F4DB5B, 0x1983A2FC,
-				0x943E1ADB, 0xD9389E6B, 0xD1039C2C, 0xA74499AD,
-				0x593D56D9, 0xF3253C06, 0x2ADC1FFC};
 
 	en_dbg(DRV, priv, "Configuring rss steering\n");
 	err = mlx4_qp_reserve_range(mdev->dev, priv->rx_ring_num,
@@ -1226,8 +1223,7 @@ int mlx4_en_config_rss_steer(struct mlx4_en_priv *priv)
 
 	rss_context->flags = rss_mask;
 	rss_context->hash_fn = MLX4_RSS_HASH_TOP;
-	for (i = 0; i < 10; i++)
-		rss_context->rss_key[i] = cpu_to_be32(rsskey[i]);
+	netdev_rss_key_fill(rss_context->rss_key, MLX4_EN_RSS_KEY_SIZE);
 
 	err = mlx4_qp_to_ready(mdev->dev, &priv->res.mtt, &context,
 			       &rss_map->indir_qp, &rss_map->indir_state);

include/linux/mlx4/qp.h

@@ -120,13 +120,15 @@ enum {
 	MLX4_RSS_QPC_FLAG_OFFSET		= 13,
 };
 
+#define MLX4_EN_RSS_KEY_SIZE 40
+
 struct mlx4_rss_context {
 	__be32			base_qpn;
 	__be32			default_qpn;
 	u16			reserved;
 	u8			hash_fn;
 	u8			flags;
-	__be32			rss_key[10];
+	__be32			rss_key[MLX4_EN_RSS_KEY_SIZE / sizeof(__be32)];
 	__be32			base_qpn_udp;
 };