From:   Oliver Hartkopp <socketcan@hartkopp.net>
To:     linux-can@vger.kernel.org
Cc:     Oliver Hartkopp <socketcan@hartkopp.net>,
        Oleksij Rempel <o.rempel@pengutronix.de>,
        Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [PATCH] can: allow MSG_CMSG_COMPAT flag in recvmsg() syscalls
Date:   Thu,  6 Apr 2023 13:08:45 +0200
Message-Id: <20230406110845.5180-1-socketcan@hartkopp.net>
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Precedence: bulk

The control messages provided by j1939 and isotp support MSG_CMSG_COMPAT
but blocked recvmsg() syscalls that have set this flag, e.g. on 32bit
ARM systems.

Link: https://github.com/hartkopp/can-isotp/issues/59
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/isotp.c        | 2 +-
 net/can/j1939/socket.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 9bc344851704..fd0e297a8584 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1099,11 +1099,11 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	struct sock *sk = sock->sk;
 	struct sk_buff *skb;
 	struct isotp_sock *so = isotp_sk(sk);
 	int ret = 0;
 
-	if (flags & ~(MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK))
+	if (flags & ~(MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK | MSG_CMSG_COMPAT))
 		return -EINVAL;
 
 	if (!so->bound)
 		return -EADDRNOTAVAIL;
 
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 7e90f9e61d9b..1790469b2580 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -796,11 +796,11 @@ static int j1939_sk_recvmsg(struct socket *sock, struct msghdr *msg,
 	struct sock *sk = sock->sk;
 	struct sk_buff *skb;
 	struct j1939_sk_buff_cb *skcb;
 	int ret = 0;
 
-	if (flags & ~(MSG_DONTWAIT | MSG_ERRQUEUE))
+	if (flags & ~(MSG_DONTWAIT | MSG_ERRQUEUE | MSG_CMSG_COMPAT))
 		return -EINVAL;
 
 	if (flags & MSG_ERRQUEUE)
 		return sock_recv_errqueue(sock->sk, msg, size, SOL_CAN_J1939,
 					  SCM_J1939_ERRQUEUE);
-- 
2.30.2