Cong Wang wrote:
> From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
>
> Implement ->read_sock() for AF_UNIX datagram socket, it is
> pretty much similar to udp_read_sock().
>
> Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
> Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> ---
> net/unix/af_unix.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 5a31307ceb76..f4dc22db371d 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -661,6 +661,8 @@ static ssize_t unix_stream_splice_read(struct socket *, loff_t *ppos,
> unsigned int flags);
> static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t);
> static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int);
> +static int unix_read_sock(struct sock *sk, read_descriptor_t *desc,
> + sk_read_actor_t recv_actor);
> static int unix_dgram_connect(struct socket *, struct sockaddr *,
> int, int);
> static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t);
> @@ -738,6 +740,7 @@ static const struct proto_ops unix_dgram_ops = {
> .listen = sock_no_listen,
> .shutdown = unix_shutdown,
> .sendmsg = unix_dgram_sendmsg,
> + .read_sock = unix_read_sock,
> .recvmsg = unix_dgram_recvmsg,
> .mmap = sock_no_mmap,
> .sendpage = sock_no_sendpage,
> @@ -2183,6 +2186,41 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> return err;
> }
>
> +static int unix_read_sock(struct sock *sk, read_descriptor_t *desc,
> + sk_read_actor_t recv_actor)
> +{
> + int copied = 0;
> +
> + while (1) {
> + struct unix_sock *u = unix_sk(sk);
> + struct sk_buff *skb;
> + int used, err;
> +
> + mutex_lock(&u->iolock);
> + skb = skb_recv_datagram(sk, 0, 1, &err);
> + if (!skb) {
> + mutex_unlock(&u->iolock);
> + return err;
Here we should check copied and break if copied is >0. Sure the caller here
has desc.count = 1 but its still fairly fragile.
> + }
> +
> + used = recv_actor(desc, skb, 0, skb->len);
> + if (used <= 0) {
> + if (!copied)
> + copied = used;
> + mutex_unlock(&u->iolock);
> + break;
> + } else if (used <= skb->len) {
> + copied += used;
> + }
> + mutex_unlock(&u->iolock);
> +
> + if (!desc->count)
> + break;
> + }
> +
> + return copied;
> +}
> +
> /*
> * Sleep until more data has arrived. But check for races..
> */
> --
> 2.25.1
>
