Merge branch 'bug-fixes-for-rss-symmetric-xor'

Ahmed Zaki says:

====================
Bug fixes for RSS symmetric-xor

A couple of fixes for the symmetric-xor recently merged in net-next [1].

The first patch copies the xfrm value back to user-space when ethtool is
built with --disable-netlink. The second allows ethtool to change other
RSS attributes while not changing the xfrm values.

Link: https://lore.kernel.org/netdev/20231213003321.605376-1-ahmed.zaki@intel.com/ [1]
====================

Link: https://lore.kernel.org/r/20231221184235.9192-1-ahmed.zaki@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/ethtool.h

@@ -2002,6 +2002,7 @@ static inline int ethtool_validate_duplex(__u8 duplex)
  * be exploited to reduce the RSS queue spread.
  */
 #define	RXH_XFRM_SYM_XOR	(1 << 0)
+#define	RXH_XFRM_NO_CHANGE	0xff
 
 /* L2-L4 network traffic flow types */
 #define	TCP_V4_FLOW	0x01	/* hash or spec (tcp_ip4_spec) */

net/ethtool/ioctl.c

@@ -1251,6 +1251,11 @@ static noinline_for_stack int ethtool_get_rxfh(struct net_device *dev,
 	if (copy_to_user(useraddr + offsetof(struct ethtool_rxfh, hfunc),
 			 &rxfh_dev.hfunc, sizeof(rxfh.hfunc))) {
 		ret = -EFAULT;
+	} else if (copy_to_user(useraddr +
+				offsetof(struct ethtool_rxfh, input_xfrm),
+				&rxfh_dev.input_xfrm,
+				sizeof(rxfh.input_xfrm))) {
+		ret = -EFAULT;
 	} else if (copy_to_user(useraddr +
 			      offsetof(struct ethtool_rxfh, rss_config[0]),
 			      rss_config, total_size)) {
@@ -1299,14 +1304,16 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 		return -EOPNOTSUPP;
 
 	/* If either indir, hash key or function is valid, proceed further.
-	 * Must request at least one change: indir size, hash key or function.
+	 * Must request at least one change: indir size, hash key, function
+	 * or input transformation.
 	 */
 	if ((rxfh.indir_size &&
 	     rxfh.indir_size != ETH_RXFH_INDIR_NO_CHANGE &&
 	     rxfh.indir_size != dev_indir_size) ||
 	    (rxfh.key_size && (rxfh.key_size != dev_key_size)) ||
 	    (rxfh.indir_size == ETH_RXFH_INDIR_NO_CHANGE &&
-	     rxfh.key_size == 0 && rxfh.hfunc == ETH_RSS_HASH_NO_CHANGE))
+	     rxfh.key_size == 0 && rxfh.hfunc == ETH_RSS_HASH_NO_CHANGE &&
+	     rxfh.input_xfrm == RXH_XFRM_NO_CHANGE))
 		return -EINVAL;
 
 	if (rxfh.indir_size != ETH_RXFH_INDIR_NO_CHANGE)