[PATCH net v2 0/3] can: j1939: fix some standard conformance problems

This patchset fixes 3 standard conformance problems in the j1939 stack.

v2:
- Add netdev_err_once() to indicate bad messages on the bus.
- Fix the if statement in the third patch to avoid breaking ETP
  functionality.

Zhang Changzhong (3):
  can: j1939: j1939_tp_cmd_recv(): ignore abort message in the BAM
    transport
  can: j1939: j1939_can_recv(): ignore messages with invalid source
    address
  can: j1939: j1939_tp_cmd_recv(): check the dst address of TP.CM_BAM

 net/can/j1939/main.c      |  6 ++++++
 net/can/j1939/transport.c | 11 +++++++++++
 2 files changed, 17 insertions(+)

-- 
2.9.5

According to SAE-J1939-82 2015 (A.3.6 Row 2), a receiver should never
send TP.CM_CTS to the global address, so we can add a check in
j1939_can_recv() to drop messages with invalid source address.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <redacted>
---
 net/can/j1939/main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index 9bc55ec..461894e 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c

@@ -75,6 +75,12 @@ static void j1939_can_recv(struct sk_buff *iskb, void *data)
 	skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
 	/* set default message type */
 	skcb->addr.type = J1939_TP;
+	if (!j1939_address_is_valid(skcb->addr.sa)) {
+		netdev_err_once(priv->ndev, "%s: sa is broadcast address, ignoring!\n",
+				__func__);
+		goto done;
+	}
+
 	if (j1939_pgn_is_pdu1(skcb->addr.pgn)) {
 		/* Type 1: with destination address */
 		skcb->addr.da = skcb->addr.pgn;

-- 
2.9.5

The TP.CM_BAM message must be sent to the global address [1], so add a
check to drop TP.CM_BAM sent to a non-global address.

Without this patch, the receiver will treat the following packets as
normal RTS/CTS tranport:
18EC0102#20090002FF002301
18EB0102#0100000000000000
18EB0102#020000FFFFFFFFFF

[1] SAE-J1939-82 2015 A.3.3 Row 1.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <redacted>
---
 net/can/j1939/transport.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 05eb3d0..a271688 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c

@@ -2023,6 +2023,11 @@ static void j1939_tp_cmd_recv(struct j1939_priv *priv, struct sk_buff *skb)
 		extd = J1939_ETP;
 		fallthrough;
 	case J1939_TP_CMD_BAM:
+		if (cmd == J1939_TP_CMD_BAM && !j1939_cb_is_broadcast(skcb)) {
+			netdev_err_once(priv->ndev, "%s: BAM to unicast (%02x), ignoring!\n",
+					__func__, skcb->addr.sa);
+			return;
+		}
 		fallthrough;
 	case J1939_TP_CMD_RTS:
 		if (skcb->addr.type != extd)

-- 
2.9.5

This patch prevents BAM transport from being closed by receiving abort
message, as specified in SAE-J1939-82 2015 (A.3.3 Row 4).

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <redacted>
---
 net/can/j1939/transport.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 6c0a0eb..05eb3d0 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c

@@ -2085,6 +2085,12 @@ static void j1939_tp_cmd_recv(struct j1939_priv *priv, struct sk_buff *skb)
 		break;
 
 	case J1939_ETP_CMD_ABORT: /* && J1939_TP_CMD_ABORT */
+		if (j1939_cb_is_broadcast(skcb)) {
+			netdev_err_once(priv->ndev, "%s: abort to broadcast (%02x), ignoring!\n",
+					__func__, skcb->addr.sa);
+			return;
+		}
+
 		if (j1939_tp_im_transmitter(skcb))
 			j1939_xtp_rx_abort(priv, skb, true);
 

-- 
2.9.5

On Thu, Oct 28, 2021 at 10:38:25PM +0800, Zhang Changzhong wrote:

This patch prevents BAM transport from being closed by receiving abort
message, as specified in SAE-J1939-82 2015 (A.3.3 Row 4).

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <redacted>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

On Thu, Oct 28, 2021 at 10:38:26PM +0800, Zhang Changzhong wrote:

According to SAE-J1939-82 2015 (A.3.6 Row 2), a receiver should never
send TP.CM_CTS to the global address, so we can add a check in
j1939_can_recv() to drop messages with invalid source address.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <redacted>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

On Thu, Oct 28, 2021 at 10:38:27PM +0800, Zhang Changzhong wrote:

The TP.CM_BAM message must be sent to the global address [1], so add a
check to drop TP.CM_BAM sent to a non-global address.

Without this patch, the receiver will treat the following packets as
normal RTS/CTS tranport:
18EC0102#20090002FF002301
18EB0102#0100000000000000
18EB0102#020000FFFFFFFFFF

[1] SAE-J1939-82 2015 A.3.3 Row 1.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <redacted>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

On 28.10.2021 22:38:24, Zhang Changzhong wrote:

This patchset fixes 3 standard conformance problems in the j1939 stack.

Applied to linux-can/testing added stable on Cc.

thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |