RE: [Patch bpf-next v3 02/10] af_unix: implement ->read_sock() for sockmap
From: John Fastabend <john.fastabend@gmail.com>
Date: 2021-05-11 05:34:42
Also in:
bpf
Cong Wang wrote:
quoted hunk ↗ jump to hunk
From: Cong Wang <redacted> Implement ->read_sock() for AF_UNIX datagram socket, it is pretty much similar to udp_read_sock(). Cc: John Fastabend <john.fastabend@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Jakub Sitnicki <jakub@cloudflare.com> Cc: Lorenz Bauer <redacted> Signed-off-by: Cong Wang <redacted> --- 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