can: netlink: allow user to turn off unsupported features

The sanity checks on the control modes will reject any request related
to an unsupported features, even turning it off.

Example on an interface which does not support CAN-FD:

$ ip link set can0 type can bitrate 500000 fd off
RTNETLINK answers: Operation not supported

This patch lets such command go through (but requests to turn on an
unsupported feature are, of course, still denied).

Link: https://lore.kernel.org/r/20210815033248.98111-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 147c23d7dab7f39b4ebec5c5a314c887c97c5073..80425636049d2e9bcbdcab3b61337525dd00fd38 100644 (file)
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -116,7 +116,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
                maskedflags = cm->flags & cm->mask;
 
                /* check whether provided bits are allowed to be passed */
-               if (cm->mask & ~(priv->ctrlmode_supported | ctrlstatic))
+               if (maskedflags & ~(priv->ctrlmode_supported | ctrlstatic))
                        return -EOPNOTSUPP;
 
                /* do not check for static fd-non-iso if 'fd' is disabled */