Merge branch 'rss_key_fill'

Eric Dumazet says:

====================
net: provide common RSS key infrastructure

RSS (Receive Side Scaling) uses a 40 bytes key to provide hash for incoming
packets to select appropriate incoming queue on NIC.

Hash algo (Toeplitz) is also well known and documented by Microsoft
(search for "Verifying the RSS Hash Calculation")

Problem is that some drivers use a well known key.
It makes very easy for attackers to target one particular RX queue,
knowing that number of RX queues is a power of two, or at least some
small number.

Other drivers use a random value per port, making difficult
tuning on bonding setups.

Lets add a common infrastructure, so that host gets an unique
RSS key, and drivers do not have to worry about this.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index b0f84f5ddda..715f51f321e 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/rtnetlink.h>
 #include <linux/sched.h>
+#include <linux/net.h>
 
 /*
  * Some useful ethtool_ops methods that're device independent.
@@ -573,6 +574,16 @@ static int ethtool_copy_validate_indir(u32 *indir, void __user *useraddr,
 	return 0;
 }
 
+u8 netdev_rss_key[NETDEV_RSS_KEY_LEN];
+
+void netdev_rss_key_fill(void *buffer, size_t len)
+{
+	BUG_ON(len > sizeof(netdev_rss_key));
+	net_get_random_once(netdev_rss_key, sizeof(netdev_rss_key));
+	memcpy(buffer, netdev_rss_key, len);
+}
+EXPORT_SYMBOL(netdev_rss_key_fill);
+
 static noinline_for_stack int ethtool_get_rxfh_indir(struct net_device *dev,
 						     void __user *useraddr)
 {