From d0cfa548dbde354de986911d3913897b5448faad Mon Sep 17 00:00:00 2001
From: Lior Nahmanson <liorna@nvidia.com>
Date: Sun, 30 Jan 2022 13:37:52 +0200
Subject: net: macsec: Verify that send_sci is on when setting Tx sci
 explicitly

When setting Tx sci explicit, the Rx side is expected to use this
sci and not recalculate it from the packet.However, in case of Tx sci
is explicit and send_sci is off, the receiver is wrongly recalculate
the sci from the source MAC address which most likely be different
than the explicit sci.

Fix by preventing such configuration when macsec newlink is established
and return EINVAL error code on such cases.

Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Lior Nahmanson <liorna@nvidia.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Raed Salem <raeds@nvidia.com>
Link: https://lore.kernel.org/r/1643542672-29403-1-git-send-email-raeds@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/macsec.c | 9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -4047,6 +4047,15 @@ static int macsec_newlink(struct net *ne
 	    !macsec_check_offload(macsec->offload, macsec))
 		return -EOPNOTSUPP;
 
+	/* send_sci must be set to true when transmit sci explicitly is set */
+	if ((data && data[IFLA_MACSEC_SCI]) &&
+	    (data && data[IFLA_MACSEC_INC_SCI])) {
+		u8 send_sci = !!nla_get_u8(data[IFLA_MACSEC_INC_SCI]);
+
+		if (!send_sci)
+			return -EINVAL;
+	}
+
 	if (data && data[IFLA_MACSEC_ICV_LEN])
 		icv_len = nla_get_u8(data[IFLA_MACSEC_ICV_LEN]);
 	mtu = real_dev->mtu - icv_len - macsec_extra_len(true);