[PATCH 5.10 007/121] can: isotp: add SF_BROADCAST support for functional addressing

Greg Kroah-Hartman
2022-02-21T09:10:15Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

commit 921ca574cd382142add8b12d0a7117f495510de5 upstream.

When CAN_ISOTP_SF_BROADCAST is set in the CAN_ISOTP_OPTS flags the CAN_ISOTP
socket is switched into functional addressing mode, where only single frame
(SF) protocol data units can be send on the specified CAN interface and the
given tp.tx_id after bind().

In opposite to normal and extended addressing this socket does not register a
CAN-ID for reception which would be needed for a 1-to-1 ISOTP connection with a
segmented bi-directional data transfer.

Sending SFs on this socket is therefore a TX-only 'broadcast' operation.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Thomas Wagner <thwa1@web.de>
Link: https://lore.kernel.org/r/20201206144731.4609-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/uapi/linux/can/isotp.h | 2 -
net/can/isotp.c | 50 +++++++++++++++++++++++++++++------------
2 files changed, 37 insertions(+), 15 deletions(-)

--- a/include/uapi/linux/can/isotp.h
+++ b/include/uapi/linux/can/isotp.h
@@ -135,7 +135,7 @@ struct can_isotp_ll_options {
#define CAN_ISOTP_FORCE_RXSTMIN 0x100 /* ignore CFs depending on rx stmin */
#define CAN_ISOTP_RX_EXT_ADDR 0x200 /* different rx extended addressing */
#define CAN_ISOTP_WAIT_TX_DONE 0x400 /* wait for tx completion */
-
+#define CAN_ISOTP_SF_BROADCAST 0x800 /* 1-to-N functional addressing */

/* default values */

--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -888,6 +888,16 @@ static int isotp_sendmsg(struct socket *
goto err_out_drop;
}

+ /* take care of a potential SF_DL ESC offset for TX_DL > 8 */
+ off = (so->tx.ll_dl > CAN_MAX_DLEN) ? 1 : 0;
+
+ /* does the given data fit into a single frame for SF_BROADCAST? */
+ if ((so->opt.flags & CAN_ISOTP_SF_BROADCAST) &&
+ (size > so->tx.ll_dl - SF_PCI_SZ4 - ae - off)) {
+ err = -EINVAL;
+ goto err_out_drop;
+ }
+
err = memcpy_from_msg(so->tx.buf, msg, size);
if (err < 0)
goto err_out_drop;
@@ -915,9 +925,6 @@ static int isotp_sendmsg(struct socket *
cf = (struct canfd_frame *)skb->data;
skb_put_zero(skb, so->ll.mtu);

- /* take care of a potential SF_DL ESC offset for TX_DL > 8 */
- off = (so->tx.ll_dl > CAN_MAX_DLEN) ? 1 : 0;
-
/* check for single frame transmission depending on TX_DL */
if (size <= so->tx.ll_dl - SF_PCI_SZ4 - ae - off) {
/* The message size generally fits into a SingleFrame - good.
@@ -1057,7 +1064,7 @@ static int isotp_release(struct socket *
lock_sock(sk);

/* remove current filters & unregister */
- if (so->bound) {
+ if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST))) {
if (so->ifindex) {
struct net_device *dev;

@@ -1097,15 +1104,12 @@ static int isotp_bind(struct socket *soc
struct net_device *dev;
int err = 0;
int notify_enetdown = 0;
+ int do_rx_reg = 1;

if (len < ISOTP_MIN_NAMELEN)
return -EINVAL;

- if (addr->can_addr.tp.rx_id == addr->can_addr.tp.tx_id)
- return -EADDRNOTAVAIL;
-
- if ((addr->can_addr.tp.rx_id | addr->can_addr.tp.tx_id) &
- (CAN_ERR_FLAG | CAN_RTR_FLAG))
+ if (addr->can_addr.tp.tx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
return -EADDRNOTAVAIL;

if (!addr->can_ifindex)
@@ -1113,6 +1117,23 @@ static int isotp_bind(struct socket *soc

lock_sock(sk);

+ /* do not register frame reception for functional addressing */
+ if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
+ do_rx_reg = 0;
+
+ /* do not validate rx address for functional addressing */
+ if (do_rx_reg) {
+ if (addr->can_addr.tp.rx_id == addr->can_addr.tp.tx_id) {
+ err = -EADDRNOTAVAIL;
+ goto out;
+ }
+
+ if (addr->can_addr.tp.rx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG)) {
+ err = -EADDRNOTAVAIL;
+ goto out;
+ }
+ }
+
if (so->bound && addr->can_ifindex == so->ifindex &&
addr->can_addr.tp.rx_id == so->rxid &&
addr->can_addr.tp.tx_id == so->txid)
@@ -1138,13 +1159,14 @@ static int isotp_bind(struct socket *soc

ifindex = dev->ifindex;

- can_rx_register(net, dev, addr->can_addr.tp.rx_id,
- SINGLE_MASK(addr->can_addr.tp.rx_id), isotp_rcv, sk,
- "isotp", sk);
+ if (do_rx_reg)
+ can_rx_register(net, dev, addr->can_addr.tp.rx_id,
+ SINGLE_MASK(addr->can_addr.tp.rx_id),
+ isotp_rcv, sk, "isotp", sk);

dev_put(dev);

- if (so->bound) {
+ if (so->bound && do_rx_reg) {
/* unregister old filter */
if (so->ifindex) {
dev = dev_get_by_index(net, so->ifindex);
@@ -1357,7 +1379,7 @@ static void isotp_notify(struct isotp_so
case NETDEV_UNREGISTER:
lock_sock(sk);
/* remove current filters & unregister */
- if (so->bound)
+ if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST)))
can_rx_unregister(dev_net(dev), dev, so->rxid,
SINGLE_MASK(so->rxid),
isotp_rcv, sk);