Subject: [PATCH 1/2] can-isotp: block setsockopt on bound sockets

From: Oliver Hartkopp <[email-masked]>
Date: Thu, 3 Dec 2020 15:06:03 +0100

The isotp socket can be widely configured in its behaviour regarding
addressing types, fill-ups, receive pattern tests and link layer length.
Usually all these settings need to be fixed before bind() and can not
be changed afterwards.

This patch adds a check to enforce the common usage pattern.

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Tested-by: Thomas Wagner <[email-masked]>
Signed-off-by: Oliver Hartkopp <[email-masked]>
---
 net/can/isotp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index d78ab13bd8be..26bdc3c20b7e 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1155,10 +1155,13 @@ static int isotp_setsockopt(struct socket *sock, int level, int optname,
 	int ret = 0;
 
 	if (level != SOL_CAN_ISOTP)
 		return -EINVAL;
 
+	if (so->bound)
+		return -EISCONN;
+
 	switch (optname) {
 	case CAN_ISOTP_OPTS:
 		if (optlen != sizeof(struct can_isotp_options))
 			return -EINVAL;
 
-- 
2.29.2