can: canxl: add virtual CAN network identifier support

CAN XL data frames contain an 8-bit virtual CAN network identifier (VCID).
A VCID value of zero represents an 'untagged' CAN XL frame.

To receive and send these optional VCIDs via CAN_RAW sockets a new socket
option CAN_RAW_XL_VCID_OPTS is introduced to define/access VCID content:

- tx: set the outgoing VCID value by the kernel (one fixed 8-bit value)
- tx: pass through VCID values from the user space (e.g. for traffic replay)
- rx: apply VCID receive filter (value/mask) to be passed to the user space

With the 'tx pass through' option CAN_RAW_XL_VCID_TX_PASS all valid VCID
values can be sent, e.g. to replay full qualified CAN XL traffic.

The VCID value provided for the CAN_RAW_XL_VCID_TX_SET option will
override the VCID value in the struct canxl_frame.prio defined for
CAN_RAW_XL_VCID_TX_PASS when both flags are set.

With a rx_vcid_mask of zero all possible VCID values (0x00 - 0xFF) are
passed to the user space when the CAN_RAW_XL_VCID_RX_FILTER flag is set.
Without this flag only untagged CAN XL frames (VCID = 0x00) are delivered
to the user space (default).

The 8-bit VCID is stored inside the CAN XL prio element (only in CAN XL
frames!) to not interfere with other CAN content or the CAN filters
provided by the CAN_RAW sockets and kernel infrastruture.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20240212213550.18516-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/uapi/linux/can/raw.h b/include/uapi/linux/can/raw.h
index 31622c9b7988..e024d896e278 100644
--- a/include/uapi/linux/can/raw.h
+++ b/include/uapi/linux/can/raw.h
@@ -65,6 +65,22 @@ enum {
 	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
 	CAN_RAW_JOIN_FILTERS,	/* all filters must match to trigger */
 	CAN_RAW_XL_FRAMES,	/* allow CAN XL frames (default:off) */
+	CAN_RAW_XL_VCID_OPTS,	/* CAN XL VCID configuration options */
 };
 
+/* configuration for CAN XL virtual CAN identifier (VCID) handling */
+struct can_raw_vcid_options {
+
+	__u8 flags;		/* flags for vcid (filter) behaviour */
+	__u8 tx_vcid;		/* VCID value set into canxl_frame.prio */
+	__u8 rx_vcid;		/* VCID value for VCID filter */
+	__u8 rx_vcid_mask;	/* VCID mask for VCID filter */
+
+};
+
+/* can_raw_vcid_options.flags for CAN XL virtual CAN identifier handling */
+#define CAN_RAW_XL_VCID_TX_SET		0x01
+#define CAN_RAW_XL_VCID_TX_PASS		0x02
+#define CAN_RAW_XL_VCID_RX_FILTER	0x04
+
 #endif /* !_UAPI_CAN_RAW_H */