releases/6.9.10/net-ethtool-fix-rss-setting.patch

From e3d57eb0862cf6ff18dd67bab11a41e01ab74a4c Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 10 Jul 2024 15:55:38 -0700
Subject: net: ethtool: Fix RSS setting

From: Saeed Mahameed <saeedm@nvidia.com>

[ Upstream commit 503757c809281a24d50ac2538401d3b1302b301c ]

When user submits a rxfh set command without touching XFRM_SYM_XOR,
rxfh.input_xfrm is set to RXH_XFRM_NO_CHANGE, which is equal to 0xff.

Testing if (rxfh.input_xfrm & RXH_XFRM_SYM_XOR &&
	    !ops->cap_rss_sym_xor_supported)
		return -EOPNOTSUPP;

Will always be true on devices that don't set cap_rss_sym_xor_supported,
since rxfh.input_xfrm & RXH_XFRM_SYM_XOR is always true, if input_xfrm
was not set, i.e RXH_XFRM_NO_CHANGE=0xff, which will result in failure
of any command that doesn't require any change of XFRM, e.g RSS context
or hash function changes.

To avoid this breakage, test if rxfh.input_xfrm != RXH_XFRM_NO_CHANGE
before testing other conditions. Note that the problem will only trigger
with XFRM-aware userspace, old ethtool CLI would continue to work.

Fixes: 0dd415d15505 ("net: ethtool: add a NO_CHANGE uAPI for new RXFH's input_xfrm")
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Ahmed Zaki <ahmed.zaki@intel.com>
Link: https://patch.msgid.link/20240710225538.43368-1-saeed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ethtool/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index e645d751a5e89..223dcd25d88a2 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1306,7 +1306,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	if (rxfh.input_xfrm && rxfh.input_xfrm != RXH_XFRM_SYM_XOR &&
 	    rxfh.input_xfrm != RXH_XFRM_NO_CHANGE)
 		return -EINVAL;
-	if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
+	if (rxfh.input_xfrm != RXH_XFRM_NO_CHANGE &&
+	    (rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
 	    !ops->cap_rss_sym_xor_supported)
 		return -EOPNOTSUPP;
 
-- 
2.43.0