[PATCH 4.5 28/87] can: fix handling of unmodifiable configuration options

Greg Kroah-Hartman
2016-05-30T20:49:26Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

commit bb208f144cf3f59d8f89a09a80efd04389718907 upstream.

As described in 'can: m_can: tag current CAN FD controllers as non-ISO'
(6cfda7fbebe) it is possible to define fixed configuration options by
setting the according bit in 'ctrlmode' and clear it in 'ctrlmode_supported'.
This leads to the incovenience that the fixed configuration bits can not be
passed by netlink even when they have the correct values (e.g. non-ISO, FD).

This patch fixes that issue and not only allows fixed set bit values to be set
again but now requires(!) to provide these fixed values at configuration time.
A valid CAN FD configuration consists of a nominal/arbitration bittiming, a
data bittiming and a control mode with CAN_CTRLMODE_FD set - which is now
enforced by a new can_validate() function. This fix additionally removed the
inconsistency that was prohibiting the support of 'CANFD-only' controller
drivers, like the RCar CAN FD.

For this reason a new helper can_set_static_ctrlmode() has been introduced to
provide a proper interface to handle static enabled CAN controller options.

Reported-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Reviewed-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/can/dev.c | 56 +++++++++++++++++++++++++++++++++++++++---
drivers/net/can/m_can/m_can.c | 2 -
include/linux/can/dev.h | 22 +++++++++++++++-
3 files changed, 73 insertions(+), 7 deletions(-)

--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -696,11 +696,17 @@ int can_change_mtu(struct net_device *de
/* allow change of MTU according to the CANFD ability of the device */
switch (new_mtu) {
case CAN_MTU:
+ /* 'CANFD-only' controllers can not switch to CAN_MTU */
+ if (priv->ctrlmode_static & CAN_CTRLMODE_FD)
+ return -EINVAL;
+
priv->ctrlmode &= ~CAN_CTRLMODE_FD;
break;

case CANFD_MTU:
- if (!(priv->ctrlmode_supported & CAN_CTRLMODE_FD))
+ /* check for potential CANFD ability */
+ if (!(priv->ctrlmode_supported & CAN_CTRLMODE_FD) &&
+ !(priv->ctrlmode_static & CAN_CTRLMODE_FD))
return -EINVAL;

priv->ctrlmode |= CAN_CTRLMODE_FD;
@@ -782,6 +788,35 @@ static const struct nla_policy can_polic
= { .len = sizeof(struct can_bittiming_const) },
};

+static int can_validate(struct nlattr *tb[], struct nlattr *data[])
+{
+ bool is_can_fd = false;
+
+ /* Make sure that valid CAN FD configurations always consist of
+ * - nominal/arbitration bittiming
+ * - data bittiming
+ * - control mode with CAN_CTRLMODE_FD set
+ */
+
+ if (data[IFLA_CAN_CTRLMODE]) {
+ struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
+
+ is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
+ }
+
+ if (is_can_fd) {
+ if (!data[IFLA_CAN_BITTIMING] || !data[IFLA_CAN_DATA_BITTIMING])
+ return -EOPNOTSUPP;
+ }
+
+ if (data[IFLA_CAN_DATA_BITTIMING]) {
+ if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
static int can_changelink(struct net_device *dev,
struct nlattr *tb[], struct nlattr *data[])
{
@@ -813,19 +848,31 @@ static int can_changelink(struct net_dev

if (data[IFLA_CAN_CTRLMODE]) {
struct can_ctrlmode *cm;
+ u32 ctrlstatic;
+ u32 maskedflags;

/* Do not allow changing controller mode while running */
if (dev->flags & IFF_UP)
return -EBUSY;
cm = nla_data(data[IFLA_CAN_CTRLMODE]);
+ ctrlstatic = priv->ctrlmode_static;
+ maskedflags = cm->flags & cm->mask;
+
+ /* check whether provided bits are allowed to be passed */
+ if (cm->mask & ~(priv->ctrlmode_supported | ctrlstatic))
+ return -EOPNOTSUPP;
+
+ /* do not check for static fd-non-iso if 'fd' is disabled */
+ if (!(maskedflags & CAN_CTRLMODE_FD))
+ ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;

- /* check whether changed bits are allowed to be modified */
- if (cm->mask & ~priv->ctrlmode_supported)
+ /* make sure static options are provided by configuration */
+ if ((maskedflags & ctrlstatic) != ctrlstatic)
return -EOPNOTSUPP;

/* clear bits to be modified and copy the flag values */
priv->ctrlmode &= ~cm->mask;
- priv->ctrlmode |= (cm->flags & cm->mask);
+ priv->ctrlmode |= maskedflags;

/* CAN_CTRLMODE_FD can only be set when driver supports FD */
if (priv->ctrlmode & CAN_CTRLMODE_FD)
@@ -966,6 +1013,7 @@ static struct rtnl_link_ops can_link_ops
.maxtype = IFLA_CAN_MAX,
.policy = can_policy,
.setup = can_setup,
+ .validate = can_validate,
.newlink = can_newlink,
.changelink = can_changelink,
.get_size = can_get_size,
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -955,7 +955,7 @@ static struct net_device *alloc_m_can_de
priv->can.do_get_berr_counter = m_can_get_berr_counter;

/* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.0.1 */
- priv->can.ctrlmode = CAN_CTRLMODE_FD_NON_ISO;
+ can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);

/* CAN_CTRLMODE_FD_NON_ISO can not be changed with M_CAN IP v3.0.1 */
priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -40,8 +40,11 @@ struct can_priv {
struct can_clock clock;

enum can_state state;
- u32 ctrlmode;
- u32 ctrlmode_supported;
+
+ /* CAN controller features - see include/uapi/linux/can/netlink.h */
+ u32 ctrlmode; /* current options setting */
+ u32 ctrlmode_supported; /* options that can be modified by netlink */
+ u32 ctrlmode_static; /* static enabled options for driver/hardware */

int restart_ms;
struct timer_list restart_timer;
@@ -108,6 +111,21 @@ static inline bool can_is_canfd_skb(cons
return skb->len == CANFD_MTU;
}

+/* helper to define static CAN controller features at device creation time */
+static inline void can_set_static_ctrlmode(struct net_device *dev,
+ u32 static_mode)
+{
+ struct can_priv *priv = netdev_priv(dev);
+
+ /* alloc_candev() succeeded => netdev_priv() is valid at this point */
+ priv->ctrlmode = static_mode;
+ priv->ctrlmode_static = static_mode;
+
+ /* override MTU which was set by default in can_setup()? */
+ if (static_mode & CAN_CTRLMODE_FD)
+ dev->mtu = CANFD_MTU;
+}
+
/* get data length from can_dlc with sanitized can_dlc */
u8 can_dlc2len(u8 can_dlc);