can: dev: fix skb drop check

In commit a6d190f8c767 ("can: skb: drop tx skb if in listen only
mode") the priv->ctrlmode element is read even on virtual CAN
interfaces that do not create the struct can_priv at startup. This
out-of-bounds read may lead to CAN frame drops for virtual CAN
interfaces like vcan and vxcan.

This patch mainly reverts the original commit and adds a new helper
for CAN interface drivers that provide the required information in
struct can_priv.

Fixes: a6d190f8c767 ("can: skb: drop tx skb if in listen only mode")
Reported-by: Dariusz Stojaczyk <[e-mail]>
Cc: Vincent Mailhol <[e-mail]>
Cc: Max Staudt <[e-mail]>
Signed-off-by: Oliver Hartkopp <[e-mail]>
Acked-by: Vincent Mailhol <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]
Cc: [e-mail] # 6.0.x
[mkl: patch pch_can, too]
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/at91_can.c

···
 	unsigned int mb, prio;
 	u32 reg_mid, reg_mcr;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	mb = get_tx_next_mb(priv);

drivers/net/can/c_can/c_can_main.c

···
 	struct c_can_tx_ring *tx_ring = &priv->tx;
 	u32 idx, obj, cmd = IF_COMM_TX;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	if (c_can_tx_busy(priv, tx_ring))

drivers/net/can/can327.c

···
 	struct can327 *elm = netdev_priv(dev);
 	struct can_frame *frame = (struct can_frame *)skb->data;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	/* We shouldn't get here after a hardware fault:

drivers/net/can/cc770/cc770.c

···
 	struct cc770_priv *priv = netdev_priv(dev);
 	unsigned int mo = obj2msgobj(CC770_OBJ_TX);
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	netif_stop_queue(dev);

drivers/net/can/ctucanfd/ctucanfd_base.c

···
 	bool ok;
 	unsigned long flags;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	if (unlikely(!CTU_CAN_FD_TXTNF(priv))) {

drivers/net/can/dev/skb.c

···
  */
 
 #include <linux/can/dev.h>
-#include <linux/can/netlink.h>
 #include <linux/module.h>
 
 #define MOD_DESC "CAN device driver interface"
···
 /* Drop a given socketbuffer if it does not contain a valid CAN frame. */
 bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb)
 {
-	struct can_priv *priv = netdev_priv(dev);
-
 	switch (ntohs(skb->protocol)) {
 	case ETH_P_CAN:
 		if (!can_is_can_skb(skb))
···
 		goto inval_skb;
 	}
 
-	if (!can_skb_headroom_valid(dev, skb)) {
+	if (!can_skb_headroom_valid(dev, skb))
 		goto inval_skb;
-	} else if (priv->ctrlmode & CAN_CTRLMODE_LISTENONLY) {
-		netdev_info_once(dev,
-				 "interface in listen only mode, dropping skb\n");
-		goto inval_skb;
-	}
 
 	return false;
 

drivers/net/can/flexcan/flexcan-core.c

···
 	u32 ctrl = FLEXCAN_MB_CODE_TX_DATA | ((can_fd_len2dlc(cfd->len)) << 16);
 	int i;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	netif_stop_queue(dev);

drivers/net/can/grcan.c

···
 	unsigned long flags;
 	u32 oneshotmode = priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	/* Trying to transmit in silent mode will generate error interrupts, but

drivers/net/can/ifi_canfd/ifi_canfd.c

···
 	u32 txst, txid, txdlc;
 	int i;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	/* Check if the TX buffer is full */

drivers/net/can/janz-ican3.c

···
 	void __iomem *desc_addr;
 	unsigned long flags;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	spin_lock_irqsave(&mod->lock, flags);

drivers/net/can/kvaser_pciefd.c

···
 	int nwords;
 	u8 count;
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	nwords = kvaser_pciefd_prepare_tx_packet(&packet, can, skb);

drivers/net/can/m_can/m_can.c

···
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	if (cdev->is_peripheral) {

drivers/net/can/mscan/mscan.c

···
 	int i, rtr, buf_id;
 	u32 can_id;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	out_8(&regs->cantier, 0);

drivers/net/can/pch_can.c

···
 	int i;
 	u32 id2;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	tx_obj_no = priv->tx_obj;

drivers/net/can/peak_canfd/peak_canfd.c

···
 	int room_left;
 	u8 len;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	msg_size = ALIGN(sizeof(*msg) + cf->len, 4);

drivers/net/can/rcar/rcar_can.c

···
 	struct can_frame *cf = (struct can_frame *)skb->data;
 	u32 data, i;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	if (cf->can_id & CAN_EFF_FLAG)	/* Extended frame format */

drivers/net/can/rcar/rcar_canfd.c

···
 	unsigned long flags;
 	u32 ch = priv->channel;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	if (cf->can_id & CAN_EFF_FLAG) {

drivers/net/can/sja1000/sja1000.c

···
 	u8 cmd_reg_val = 0x00;
 	int i;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	netif_stop_queue(dev);

drivers/net/can/slcan/slcan-core.c

···
 {
 	struct slcan *sl = netdev_priv(dev);
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	spin_lock(&sl->lock);

drivers/net/can/softing/softing_main.c

···
 	struct can_frame *cf = (struct can_frame *)skb->data;
 	uint8_t buf[DPRAM_TX_SIZE];
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	spin_lock(&card->spin);

drivers/net/can/spi/hi311x.c

···
 		return NETDEV_TX_BUSY;
 	}
 
-	if (can_dropped_invalid_skb(net, skb))
+	if (can_dev_dropped_skb(net, skb))
 		return NETDEV_TX_OK;
 
 	netif_stop_queue(net);

drivers/net/can/spi/mcp251x.c

···
 		return NETDEV_TX_BUSY;
 	}
 
-	if (can_dropped_invalid_skb(net, skb))
+	if (can_dev_dropped_skb(net, skb))
 		return NETDEV_TX_OK;
 
 	netif_stop_queue(net);

drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c

···
 	u8 tx_head;
 	int err;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	if (mcp251xfd_tx_busy(priv, tx_ring))

drivers/net/can/sun4i_can.c

···
 	canid_t id;
 	int i;
 
-	if (can_dropped_invalid_skb(dev, skb))
+	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
 	netif_stop_queue(dev);

drivers/net/can/ti_hecc.c

···
 	u32 mbxno, mbx_mask, data;
 	unsigned long flags;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	mbxno = get_tx_head_mb(priv);

drivers/net/can/usb/ems_usb.c

···
 	size_t size = CPC_HEADER_SIZE + CPC_MSG_HEADER_LEN
 			+ sizeof(struct cpc_can_msg);
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	/* create a URB, and a buffer for it, and copy the data to the URB */

drivers/net/can/usb/esd_usb.c

···
 	int ret = NETDEV_TX_OK;
 	size_t size = sizeof(struct esd_usb_msg);
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	/* create a URB, and a buffer for it, and copy the data to the URB */

drivers/net/can/usb/etas_es58x/es58x_core.c

···
 	unsigned int frame_len;
 	int ret;
 
-	if (can_dropped_invalid_skb(netdev, skb)) {
+	if (can_dev_dropped_skb(netdev, skb)) {
 		if (priv->tx_urb)
 			goto xmit_commit;
 		return NETDEV_TX_OK;

drivers/net/can/usb/gs_usb.c

···
 	unsigned int idx;
 	struct gs_tx_context *txc;
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	/* find an empty context to keep track of transmission */

drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c

···
 	unsigned int i;
 	unsigned long flags;
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	urb = usb_alloc_urb(0, GFP_ATOMIC);

drivers/net/can/usb/mcba_usb.c

···
 		.cmd_id = MBCA_CMD_TRANSMIT_MESSAGE_EV
 	};
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	ctx = mcba_usb_get_free_ctx(priv, cf);

drivers/net/can/usb/peak_usb/pcan_usb_core.c

···
 	int i, err;
 	size_t size = dev->adapter->tx_buffer_size;
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++)

drivers/net/can/usb/ucan.c

···
 	struct can_frame *cf = (struct can_frame *)skb->data;
 
 	/* check skb */
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	/* allocate a context and slow down tx path, if fifo state is low */

drivers/net/can/usb/usb_8dev.c

···
 	int i, err;
 	size_t size = sizeof(struct usb_8dev_tx_msg);
 
-	if (can_dropped_invalid_skb(netdev, skb))
+	if (can_dev_dropped_skb(netdev, skb))
 		return NETDEV_TX_OK;
 
 	/* create a URB, and a buffer for it, and copy the data to the URB */

drivers/net/can/xilinx_can.c

···
 	struct xcan_priv *priv = netdev_priv(ndev);
 	int ret;
 
-	if (can_dropped_invalid_skb(ndev, skb))
+	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
 	if (priv->devtype.flags & XCAN_FLAG_TX_MAILBOXES)

include/linux/can/dev.h

···
 	return (mtu >= CANXL_MIN_MTU && mtu <= CANXL_MAX_MTU);
 }
 
+/* drop skb if it does not contain a valid CAN frame for sending */
+static inline bool can_dev_dropped_skb(struct net_device *dev, struct sk_buff *skb)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	if (priv->ctrlmode & CAN_CTRLMODE_LISTENONLY) {
+		netdev_info_once(dev,
+				 "interface in listen only mode, dropping skb\n");
+		kfree_skb(skb);
+		dev->stats.tx_dropped++;
+		return true;
+	}
+
+	return can_dropped_invalid_skb(dev, skb);
+}
+
 void can_setup(struct net_device *dev);
 
 struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,