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authorOliver Hartkopp <socketcan@hartkopp.net>2022-03-16 17:42:58 +0100
committerMarc Kleine-Budde <mkl@pengutronix.de>2022-03-16 21:41:40 +0100
commit42bf50a1795a1854d48717b7361dbdbce496b16b (patch)
tree99da9e4a55671074d98d51a8be99cfd6e3bb361e /net/can
parent30ffd5332e06316bd69a654c06aa033872979b7c (diff)
can: isotp: support MSG_TRUNC flag when reading from socket
When providing the MSG_TRUNC flag via recvmsg() syscall the return value provides the real length of the packet or datagram, even when it was longer than the passed buffer. Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Link: https://github.com/linux-can/can-utils/issues/347#issuecomment-1065932671 Link: https://lore.kernel.org/all/20220316164258.54155-3-socketcan@hartkopp.net Suggested-by: Derek Will <derekrobertwill@gmail.com> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'net/can')
-rw-r--r--net/can/isotp.c27
1 files changed, 15 insertions, 12 deletions
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 6b6c82206c30..f6f8ba1f816d 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1047,29 +1047,28 @@ 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 err = 0;
- int noblock;
+ int noblock = flags & MSG_DONTWAIT;
+ int ret = 0;
- noblock = flags & MSG_DONTWAIT;
- flags &= ~MSG_DONTWAIT;
+ if (flags & ~(MSG_DONTWAIT | MSG_TRUNC))
+ return -EINVAL;
if (!so->bound)
return -EADDRNOTAVAIL;
- skb = skb_recv_datagram(sk, flags, noblock, &err);
+ flags &= ~MSG_DONTWAIT;
+ skb = skb_recv_datagram(sk, flags, noblock, &ret);
if (!skb)
- return err;
+ return ret;
if (size < skb->len)
msg->msg_flags |= MSG_TRUNC;
else
size = skb->len;
- err = memcpy_to_msg(msg, skb->data, size);
- if (err < 0) {
- skb_free_datagram(sk, skb);
- return err;
- }
+ ret = memcpy_to_msg(msg, skb->data, size);
+ if (ret < 0)
+ goto out_err;
sock_recv_timestamp(msg, sk, skb);
@@ -1079,9 +1078,13 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
}
+ /* set length of return value */
+ ret = (flags & MSG_TRUNC) ? skb->len : size;
+
+out_err:
skb_free_datagram(sk, skb);
- return size;
+ return ret;
}
static int isotp_release(struct socket *sock)