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mptcp: fix connect timeout handling

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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: 54f1944ed6 ("mptcp: factor out mptcp_connect()")
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/399
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2023-05-31 12:37:03 -07:00 committed by Jakub Kicinski
parent 3021dbfe3e
commit 786fc12457
2 changed files with 7 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
net/mptcp/protocol.c
View File

@ -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 @@ unlock:
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,

1
net/mptcp/protocol.h
View File

@ -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;