linux-kernel - [PATCH v4 07/20] can: netlink: refactor CAN_CTRLMODE_TDC

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250923-canxl-netlink-prep-v4-7-e720d28f66fe@kernel.org>
Date: Tue, 23 Sep 2025 15:58:32 +0900
From: Vincent Mailhol <mailhol@...nel.org>
To: Marc Kleine-Budde <mkl@...gutronix.de>, 
 Oliver Hartkopp <socketcan@...tkopp.net>
Cc: Vincent Mailhol <mailhol@...nel.org>, 
 Stéphane Grosjean <stephane.grosjean@...-networks.com>, 
 Robert Nawrath <mbro1689@...il.com>, Minh Le <minh.le.aj@...esas.com>, 
 Duy Nguyen <duy.nguyen.rh@...esas.com>, linux-can@...r.kernel.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH v4 07/20] can: netlink: refactor
 CAN_CTRLMODE_TDC_{AUTO,MANUAL} flag reset logic

CAN_CTRLMODE_TDC_AUTO and CAN_CTRLMODE_TDC_MANUAL are mutually
exclusive. This means that whenever the user switches from auto to
manual mode (or vice versa), the other flag which was set previously
needs to be cleared.

Currently, this is handled with a masking operation. It can be done in
a simpler manner by clearing any of the previous TDC flags before
copying netlink attributes. The code becomes easier to understand and
will make it easier to add the new upcoming CAN XL flags which will
have a similar reset logic as the current TDC flags.

Signed-off-by: Vincent Mailhol <mailhol@...nel.org>
---
Changelog:

v2 -> v3:

  - Fix a bug in the masking. Replace

	priv->ctrlmode &= !CAN_CTRLMODE_FD_TDC_MASK;

    by

	priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
---
 drivers/net/can/dev/netlink.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 549a2247d847dd26c8cb8c76ecb609256f549eb2..c212c7ff26cd3367d2014db99de7534077a1a841 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -255,6 +255,10 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 		if ((maskedflags & ctrlstatic) != ctrlstatic)
 			return -EOPNOTSUPP;
 
+		/* If a top dependency flag is provided, reset all its dependencies */
+		if (cm->mask & CAN_CTRLMODE_FD)
+			priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
+
 		/* clear bits to be modified and copy the flag values */
 		priv->ctrlmode &= ~cm->mask;
 		priv->ctrlmode |= maskedflags;
@@ -270,11 +274,6 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 		can_set_default_mtu(dev);
 
 		fd_tdc_flag_provided = cm->mask & CAN_CTRLMODE_FD_TDC_MASK;
-		/* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually
-		 * exclusive: make sure to turn the other one off
-		 */
-		if (fd_tdc_flag_provided)
-			priv->ctrlmode &= cm->flags | ~CAN_CTRLMODE_FD_TDC_MASK;
 	}
 
 	if (data[IFLA_CAN_BITTIMING]) {

-- 
2.49.1