can: isotp: add SF_BROADCAST support for functional addressing

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>

diff --git a/include/uapi/linux/can/isotp.h b/include/uapi/linux/can/isotp.h
index 7793b26..c55935b 100644 (file)
--- 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 */
 

diff --git a/net/can/isotp.c b/net/can/isotp.c
index d78ab13..09f781b 100644 (file)
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -865,6 +865,14 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
        if (!size || size > MAX_MSG_LENGTH)
                return -EINVAL;
 
+       /* 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))
+               return -EINVAL;
+
        err = memcpy_from_msg(so->tx.buf, msg, size);
        if (err < 0)
                return err;
@@ -891,9 +899,6 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
        cf = (struct canfd_frame *)skb->data;
        skb_put(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.
@@ -1016,7 +1021,7 @@ static int isotp_release(struct socket *sock)
        hrtimer_cancel(&so->rxtimer);
 
        /* remove current filters & unregister */
-       if (so->bound) {
+       if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST))) {
                if (so->ifindex) {
                        struct net_device *dev;
 
@@ -1052,15 +1057,25 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
        struct net_device *dev;
        int err = 0;
        int notify_enetdown = 0;
+       int do_rx_reg = 1;
 
        if (len < CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.tp))
                return -EINVAL;
 
-       if (addr->can_addr.tp.rx_id == addr->can_addr.tp.tx_id)
-               return -EADDRNOTAVAIL;
+       /* 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)
+                       return -EADDRNOTAVAIL;
+
+               if (addr->can_addr.tp.rx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
+                       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)
@@ -1093,13 +1108,14 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 
        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);
@@ -1299,7 +1315,7 @@ static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
        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);