[RFC PATCH v2 10/45] mptcp: add mptcp_poll

[Mat Martineau]

From: Florian Westphal <f...@strlen.de>

Can't use tcp_poll directly:

BUG: KASAN: slab-out-of-bounds in tcp_poll+0x17f/0x540
Read of size 4 at addr ffff88806ac5e50c by task mptcp_connect/2085
Call Trace:
 tcp_poll+0x17f/0x540
 sock_poll+0x152/0x180

Signed-off-by: Florian Westphal <f...@strlen.de>
---
 net/mptcp/protocol.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 95c302c59d2e..07508d060b3d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -257,6 +257,36 @@ static int mptcp_stream_connect(struct socket *sock, 
struct sockaddr *uaddr,
        return inet_stream_connect(msk->subflow, uaddr, addr_len, flags);
 }
 
+static __poll_t mptcp_poll(struct file *file, struct socket *sock,
+                          struct poll_table_struct *wait)
+{
+       struct mptcp_subflow_context *subflow;
+       const struct mptcp_sock *msk;
+       struct sock *sk = sock->sk;
+       struct socket *ssock;
+       __poll_t ret = 0;
+
+       msk = mptcp_sk(sk);
+       lock_sock(sk);
+       ssock = __mptcp_fallback_get_ref(msk);
+       if (ssock) {
+               release_sock(sk);
+               ret = tcp_poll(file, ssock, wait);
+               sock_put(ssock->sk);
+               return ret;
+       }
+
+       mptcp_for_each_subflow(msk, subflow) {
+               struct socket *tcp_sock;
+
+               tcp_sock = mptcp_subflow_tcp_socket(subflow);
+               ret |= tcp_poll(file, tcp_sock, wait);
+       }
+       release_sock(sk);
+
+       return ret;
+}
+
 static struct proto_ops mptcp_stream_ops;
 
 static struct inet_protosw mptcp_protosw = {
@@ -273,6 +303,7 @@ void __init mptcp_init(void)
        mptcp_stream_ops = inet_stream_ops;
        mptcp_stream_ops.bind = mptcp_bind;
        mptcp_stream_ops.connect = mptcp_stream_connect;
+       mptcp_stream_ops.poll = mptcp_poll;
 
        mptcp_subflow_init();
 
-- 
2.23.0