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Message-Id: <20230531-send-net-20230531-v1-1-47750c420571@kernel.org>
Date: Wed, 31 May 2023 12:37:03 -0700
From: Mat Martineau <martineau@...nel.org>
To: Matthieu Baerts <matthieu.baerts@...sares.net>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Geliang Tang <geliang.tang@...e.com>
Cc: netdev@...r.kernel.org, mptcp@...ts.linux.dev,
Mat Martineau <martineau@...nel.org>, Ondrej Mosnacek <omosnace@...hat.com>,
stable@...r.kernel.org
Subject: [PATCH net 1/6] mptcp: fix connect timeout handling
From: Paolo Abeni <pabeni@...hat.com>
Ondrej reported a functional issue WRT timeout handling on connect
with a nice reproducer.
The problem is that the current mptcp connect waits for both the
MPTCP socket level timeout, and the first subflow socket timeout.
The latter is not influenced/touched by the exposed setsockopt().
Overall the above makes the SO_SNDTIMEO a no-op on connect.
Since mptcp_connect is invoked via inet_stream_connect and the
latter properly handle the MPTCP level timeout, we can address the
issue making the nested subflow level connect always unblocking.
This also allow simplifying a bit the code, dropping an ugly hack
to handle the fastopen and custom proto_ops connect.
The issues predates the blamed commit below, but the current resolution
requires the infrastructure introduced there.
Fixes: 54f1944ed6d2 ("mptcp: factor out mptcp_connect()")
Reported-by: Ondrej Mosnacek <omosnace@...hat.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/399
Cc: stable@...r.kernel.org
Reviewed-by: Mat Martineau <martineau@...nel.org>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Mat Martineau <martineau@...nel.org>
---
net/mptcp/protocol.c | 29 +++++++----------------------
net/mptcp/protocol.h | 1 -
2 files changed, 7 insertions(+), 23 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 08dc53f56bc2..9cafd3b89908 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1702,7 +1702,6 @@ static int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
lock_sock(ssk);
msg->msg_flags |= MSG_DONTWAIT;
- msk->connect_flags = O_NONBLOCK;
msk->fastopening = 1;
ret = tcp_sendmsg_fastopen(ssk, msg, copied_syn, len, NULL);
msk->fastopening = 0;
@@ -3617,9 +3616,9 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
* acquired the subflow socket lock, too.
*/
if (msk->fastopening)
- err = __inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags, 1);
+ err = __inet_stream_connect(ssock, uaddr, addr_len, O_NONBLOCK, 1);
else
- err = inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags);
+ err = inet_stream_connect(ssock, uaddr, addr_len, O_NONBLOCK);
inet_sk(sk)->defer_connect = inet_sk(ssock->sk)->defer_connect;
/* on successful connect, the msk state will be moved to established by
@@ -3632,12 +3631,10 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
mptcp_copy_inaddrs(sk, ssock->sk);
- /* unblocking connect, mptcp-level inet_stream_connect will error out
- * without changing the socket state, update it here.
+ /* silence EINPROGRESS and let the caller inet_stream_connect
+ * handle the connection in progress
*/
- if (err == -EINPROGRESS)
- sk->sk_socket->state = ssock->state;
- return err;
+ return 0;
}
static struct proto mptcp_prot = {
@@ -3696,18 +3693,6 @@ static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
return err;
}
-static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
- int addr_len, int flags)
-{
- int ret;
-
- lock_sock(sock->sk);
- mptcp_sk(sock->sk)->connect_flags = flags;
- ret = __inet_stream_connect(sock, uaddr, addr_len, flags, 0);
- release_sock(sock->sk);
- return ret;
-}
-
static int mptcp_listen(struct socket *sock, int backlog)
{
struct mptcp_sock *msk = mptcp_sk(sock->sk);
@@ -3859,7 +3844,7 @@ static const struct proto_ops mptcp_stream_ops = {
.owner = THIS_MODULE,
.release = inet_release,
.bind = mptcp_bind,
- .connect = mptcp_stream_connect,
+ .connect = inet_stream_connect,
.socketpair = sock_no_socketpair,
.accept = mptcp_stream_accept,
.getname = inet_getname,
@@ -3954,7 +3939,7 @@ static const struct proto_ops mptcp_v6_stream_ops = {
.owner = THIS_MODULE,
.release = inet6_release,
.bind = mptcp_bind,
- .connect = mptcp_stream_connect,
+ .connect = inet_stream_connect,
.socketpair = sock_no_socketpair,
.accept = mptcp_stream_accept,
.getname = inet6_getname,
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 2d7b2c80a164..de4667dafe59 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -297,7 +297,6 @@ struct mptcp_sock {
nodelay:1,
fastopening:1,
in_accept_queue:1;
- int connect_flags;
struct work_struct work;
struct sk_buff *ooo_last_skb;
struct rb_root out_of_order_queue;
--
2.40.1
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