[RFC] vsock: notify server to shutdown when client has pending signal

[RFC] vsock: notify server to shutdown when client has pending signal

[Longpeng(Mike)]

The client's sk_state will be set to TCP_ESTABLISHED if the
server replay the client's connect request.
However, if the client has pending signal, its sk_state will
be set to TCP_CLOSE without notify the server, so the server
will hold the corrupt connection.

            client                        server

1. sk_state=TCP_SYN_SENT         |
2. call ->connect()              |
3. wait reply                    |
                                 | 4. sk_state=TCP_ESTABLISHED
                                 | 5. insert to connected list
                                 | 6. reply to the client
7. sk_state=TCP_ESTABLISHED      |
8. insert to connected list      |
9. *signal pending* <--------------------- the user kill client
10. sk_state=TCP_CLOSE           |
client is exiting...             |
11. call ->release()             |
     virtio_transport_close
      if (!(sk->sk_state == TCP_ESTABLISHED ||
	      sk->sk_state == TCP_CLOSING))
		return true; <------------- return at here
As a result, the server cannot notice the connection is corrupt.
So the client should notify the peer in this case.

Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Cc: Jorgen Hansen <jhansen@vmware.com>
Cc: Norbert Slusarek <nslusarek@gmx.net>
Cc: Andra Paraschiv <andraprs@amazon.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: David Brazdil <dbrazdil@google.com>
Cc: Alexander Popov <alex.popov@linux.com>
Signed-off-by: lixianming <lixianming5@huawei.com>
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
---
 net/vmw_vsock/af_vsock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 92a72f0..d5df908 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1368,6 +1368,7 @@ static int vsock_stream_connect(struct socket *sock, struct sockaddr *addr,
 		lock_sock(sk);
 
 		if (signal_pending(current)) {
+			vsock_send_shutdown(sk, SHUTDOWN_MASK);
 			err = sock_intr_errno(timeout);
 			sk->sk_state = TCP_CLOSE;
 			sock->state = SS_UNCONNECTED;
-- 
1.8.3.1

Re: [RFC] vsock: notify server to shutdown when client has pending signal

[Stefano Garzarella]

Hi,
thanks for this patch, comments below...

On Tue, May 11, 2021 at 05:41:27PM +0800, Longpeng(Mike) wrote:
>The client's sk_state will be set to TCP_ESTABLISHED if the
>server replay the client's connect request.
>However, if the client has pending signal, its sk_state will
>be set to TCP_CLOSE without notify the server, so the server
>will hold the corrupt connection.
>
>            client                        server
>
>1. sk_state=TCP_SYN_SENT         |
>2. call ->connect()              |
>3. wait reply                    |
>                                 | 4. sk_state=TCP_ESTABLISHED
>                                 | 5. insert to connected list
>                                 | 6. reply to the client
>7. sk_state=TCP_ESTABLISHED      |
>8. insert to connected list      |
>9. *signal pending* <--------------------- the user kill client
>10. sk_state=TCP_CLOSE           |
>client is exiting...             |
>11. call ->release()             |
>     virtio_transport_close
>      if (!(sk->sk_state == TCP_ESTABLISHED ||
>	      sk->sk_state == TCP_CLOSING))
>		return true; <------------- return at here
>As a result, the server cannot notice the connection is corrupt.
>So the client should notify the peer in this case.
>
>Cc: David S. Miller <davem@davemloft.net>
>Cc: Jakub Kicinski <kuba@kernel.org>
>Cc: Stefano Garzarella <sgarzare@redhat.com>
>Cc: Jorgen Hansen <jhansen@vmware.com>
>Cc: Norbert Slusarek <nslusarek@gmx.net>
>Cc: Andra Paraschiv <andraprs@amazon.com>
>Cc: Colin Ian King <colin.king@canonical.com>
>Cc: David Brazdil <dbrazdil@google.com>
>Cc: Alexander Popov <alex.popov@linux.com>
>Signed-off-by: lixianming <lixianming5@huawei.com>
>Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
>---
> net/vmw_vsock/af_vsock.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 92a72f0..d5df908 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1368,6 +1368,7 @@ static int vsock_stream_connect(struct socket *sock, struct sockaddr *addr,
> 		lock_sock(sk);
>
> 		if (signal_pending(current)) {
>+			vsock_send_shutdown(sk, SHUTDOWN_MASK);

I see the issue, but I'm not sure is okay to send the shutdown in any 
case, think about the server didn't setup the connection.

Maybe is better to set TCP_CLOSING if the socket state was 
TCP_ESTABLISHED, so the shutdown will be handled by the 
transport->release() as usual.

What do you think?

Anyway, also without the patch, the server should receive a RST if it 
sends any data to the client, but of course, is better to let it know 
the socket is closed in advance.

Thanks,
Stefano

RE: [RFC] vsock: notify server to shutdown when client has pending signal

[Longpeng (Mike, Cloud Infrastructure Service Product Dept.)]

Hi Stefano,

> -----Original Message-----
> From: Stefano Garzarella [mailto:sgarzare@redhat.com]
> Sent: Thursday, May 13, 2021 5:42 PM
> To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
> <longpeng2@huawei.com>
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Gonglei (Arei)
> <arei.gonglei@huawei.com>; Subo (Subo, Cloud Infrastructure Service Product
> Dept.) <subo7@huawei.com>; David S . Miller <davem@davemloft.net>; Jakub
> Kicinski <kuba@kernel.org>; Jorgen Hansen <jhansen@vmware.com>; Norbert
> Slusarek <nslusarek@gmx.net>; Andra Paraschiv <andraprs@amazon.com>;
> Colin Ian King <colin.king@canonical.com>; David Brazdil
> <dbrazdil@google.com>; Alexander Popov <alex.popov@linux.com>;
> lixianming (E) <lixianming5@huawei.com>
> Subject: Re: [RFC] vsock: notify server to shutdown when client has pending
> signal
> 
> Hi,
> thanks for this patch, comments below...
> 
> On Tue, May 11, 2021 at 05:41:27PM +0800, Longpeng(Mike) wrote:
> >The client's sk_state will be set to TCP_ESTABLISHED if the server
> >replay the client's connect request.
> >However, if the client has pending signal, its sk_state will be set to
> >TCP_CLOSE without notify the server, so the server will hold the
> >corrupt connection.
> >
> >            client                        server
> >
> >1. sk_state=TCP_SYN_SENT         |
> >2. call ->connect()              |
> >3. wait reply                    |
> >                                 | 4. sk_state=TCP_ESTABLISHED
> >                                 | 5. insert to connected list
> >                                 | 6. reply to the client
> >7. sk_state=TCP_ESTABLISHED      |
> >8. insert to connected list      |
> >9. *signal pending* <--------------------- the user kill client
> >10. sk_state=TCP_CLOSE           |
> >client is exiting...             |
> >11. call ->release()             |
> >     virtio_transport_close
> >      if (!(sk->sk_state == TCP_ESTABLISHED ||
> >	      sk->sk_state == TCP_CLOSING))
> >		return true; <------------- return at here As a result, the server
> >cannot notice the connection is corrupt.
> >So the client should notify the peer in this case.
> >
> >Cc: David S. Miller <davem@davemloft.net>
> >Cc: Jakub Kicinski <kuba@kernel.org>
> >Cc: Stefano Garzarella <sgarzare@redhat.com>
> >Cc: Jorgen Hansen <jhansen@vmware.com>
> >Cc: Norbert Slusarek <nslusarek@gmx.net>
> >Cc: Andra Paraschiv <andraprs@amazon.com>
> >Cc: Colin Ian King <colin.king@canonical.com>
> >Cc: David Brazdil <dbrazdil@google.com>
> >Cc: Alexander Popov <alex.popov@linux.com>
> >Signed-off-by: lixianming <lixianming5@huawei.com>
> >Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
> >---
> > net/vmw_vsock/af_vsock.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> >diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index
> >92a72f0..d5df908 100644
> >--- a/net/vmw_vsock/af_vsock.c
> >+++ b/net/vmw_vsock/af_vsock.c
> >@@ -1368,6 +1368,7 @@ static int vsock_stream_connect(struct socket *sock,
> struct sockaddr *addr,
> > 		lock_sock(sk);
> >
> > 		if (signal_pending(current)) {
> >+			vsock_send_shutdown(sk, SHUTDOWN_MASK);
> 
> I see the issue, but I'm not sure is okay to send the shutdown in any case,
> think about the server didn't setup the connection.
> 
> Maybe is better to set TCP_CLOSING if the socket state was TCP_ESTABLISHED,
> so the shutdown will be handled by the
> transport->release() as usual.
> 
> What do you think?
> 

Your method looks more gracefully, we'll try it and get back to you, thanks.

> Anyway, also without the patch, the server should receive a RST if it
> sends any data to the client, but of course, is better to let it know
> the socket is closed in advance.
> 

Yes, agree.

> Thanks,
> Stefano

RE: [RFC] vsock: notify server to shutdown when client has pending signal

[Longpeng (Mike, Cloud Infrastructure Service Product Dept.)]

Hi Stefano,

> -----Original Message-----
> From: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
> [mailto:longpeng2@huawei.com]
> Sent: Thursday, May 13, 2021 6:36 PM
> To: Stefano Garzarella <sgarzare@redhat.com>
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Gonglei (Arei)
> <arei.gonglei@huawei.com>; Subo (Subo, Cloud Infrastructure Service Product
> Dept.) <subo7@huawei.com>; David S . Miller <davem@davemloft.net>; Jakub
> Kicinski <kuba@kernel.org>; Jorgen Hansen <jhansen@vmware.com>; Norbert
> Slusarek <nslusarek@gmx.net>; Andra Paraschiv <andraprs@amazon.com>;
> Colin Ian King <colin.king@canonical.com>; David Brazdil
> <dbrazdil@google.com>; Alexander Popov <alex.popov@linux.com>;
> lixianming (E) <lixianming5@huawei.com>
> Subject: RE: [RFC] vsock: notify server to shutdown when client has pending
> signal
> 
> Hi Stefano,
> 
> > -----Original Message-----
> > From: Stefano Garzarella [mailto:sgarzare@redhat.com]
> > Sent: Thursday, May 13, 2021 5:42 PM
> > To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
> > <longpeng2@huawei.com>
> > Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Gonglei
> > (Arei) <arei.gonglei@huawei.com>; Subo (Subo, Cloud Infrastructure
> > Service Product
> > Dept.) <subo7@huawei.com>; David S . Miller <davem@davemloft.net>;
> > Jakub Kicinski <kuba@kernel.org>; Jorgen Hansen <jhansen@vmware.com>;
> > Norbert Slusarek <nslusarek@gmx.net>; Andra Paraschiv
> > <andraprs@amazon.com>; Colin Ian King <colin.king@canonical.com>;
> > David Brazdil <dbrazdil@google.com>; Alexander Popov
> > <alex.popov@linux.com>; lixianming (E) <lixianming5@huawei.com>
> > Subject: Re: [RFC] vsock: notify server to shutdown when client has
> > pending signal
> >
> > Hi,
> > thanks for this patch, comments below...
> >
> > On Tue, May 11, 2021 at 05:41:27PM +0800, Longpeng(Mike) wrote:
> > >The client's sk_state will be set to TCP_ESTABLISHED if the server
> > >replay the client's connect request.
> > >However, if the client has pending signal, its sk_state will be set
> > >to TCP_CLOSE without notify the server, so the server will hold the
> > >corrupt connection.
> > >
> > >            client                        server
> > >
> > >1. sk_state=TCP_SYN_SENT         |
> > >2. call ->connect()              |
> > >3. wait reply                    |
> > >                                 | 4. sk_state=TCP_ESTABLISHED
> > >                                 | 5. insert to connected list
> > >                                 | 6. reply to the client
> > >7. sk_state=TCP_ESTABLISHED      |
> > >8. insert to connected list      |
> > >9. *signal pending* <--------------------- the user kill client
> > >10. sk_state=TCP_CLOSE           |
> > >client is exiting...             |
> > >11. call ->release()             |
> > >     virtio_transport_close
> > >      if (!(sk->sk_state == TCP_ESTABLISHED ||
> > >	      sk->sk_state == TCP_CLOSING))
> > >		return true; <------------- return at here As a result, the server
> > >cannot notice the connection is corrupt.
> > >So the client should notify the peer in this case.
> > >
> > >Cc: David S. Miller <davem@davemloft.net>
> > >Cc: Jakub Kicinski <kuba@kernel.org>
> > >Cc: Stefano Garzarella <sgarzare@redhat.com>
> > >Cc: Jorgen Hansen <jhansen@vmware.com>
> > >Cc: Norbert Slusarek <nslusarek@gmx.net>
> > >Cc: Andra Paraschiv <andraprs@amazon.com>
> > >Cc: Colin Ian King <colin.king@canonical.com>
> > >Cc: David Brazdil <dbrazdil@google.com>
> > >Cc: Alexander Popov <alex.popov@linux.com>
> > >Signed-off-by: lixianming <lixianming5@huawei.com>
> > >Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
> > >---
> > > net/vmw_vsock/af_vsock.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > >diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > >index
> > >92a72f0..d5df908 100644
> > >--- a/net/vmw_vsock/af_vsock.c
> > >+++ b/net/vmw_vsock/af_vsock.c
> > >@@ -1368,6 +1368,7 @@ static int vsock_stream_connect(struct socket
> > >*sock,
> > struct sockaddr *addr,
> > > 		lock_sock(sk);
> > >
> > > 		if (signal_pending(current)) {
> > >+			vsock_send_shutdown(sk, SHUTDOWN_MASK);
> >
> > I see the issue, but I'm not sure is okay to send the shutdown in any
> > case, think about the server didn't setup the connection.
> >
> > Maybe is better to set TCP_CLOSING if the socket state was
> > TCP_ESTABLISHED, so the shutdown will be handled by the
> > transport->release() as usual.
> >
> > What do you think?
> >
> 
> Your method looks more gracefully, we'll try it and get back to you, thanks.
> 

As your suggestion, the following code can solve the problem:

                if (signal_pending(current)) {
                        err = sock_intr_errno(timeout);
-                       sk->sk_state = TCP_CLOSE;
+                       sk->sk_state = TCP_CLOSING;
                        sock->state = SS_UNCONNECTED;
                        vsock_transport_cancel_pkt(vsk);
                        goto out_wait;

This will send shutdown to the server even if the connection is not established, but
I don't see any side effects yet, right ?

The problem is also in the timeout case, we should fix it together ?


> > Anyway, also without the patch, the server should receive a RST if it
> > sends any data to the client, but of course, is better to let it know
> > the socket is closed in advance.
> >
> 
> Yes, agree.
> 
> > Thanks,
> > Stefano

Re: [RFC] vsock: notify server to shutdown when client has pending signal

[Stefano Garzarella]

On Mon, May 17, 2021 at 02:18:51AM +0000, Longpeng (Mike, Cloud Infrastructure Service Product Dept.) wrote:
>Hi Stefano,
>
>> -----Original Message-----
>> From: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
>> [mailto:longpeng2@huawei.com]
>> Sent: Thursday, May 13, 2021 6:36 PM
>> To: Stefano Garzarella <sgarzare@redhat.com>
>> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Gonglei (Arei)
>> <arei.gonglei@huawei.com>; Subo (Subo, Cloud Infrastructure Service Product
>> Dept.) <subo7@huawei.com>; David S . Miller <davem@davemloft.net>; Jakub
>> Kicinski <kuba@kernel.org>; Jorgen Hansen <jhansen@vmware.com>; Norbert
>> Slusarek <nslusarek@gmx.net>; Andra Paraschiv <andraprs@amazon.com>;
>> Colin Ian King <colin.king@canonical.com>; David Brazdil
>> <dbrazdil@google.com>; Alexander Popov <alex.popov@linux.com>;
>> lixianming (E) <lixianming5@huawei.com>
>> Subject: RE: [RFC] vsock: notify server to shutdown when client has pending
>> signal
>>
>> Hi Stefano,
>>
>> > -----Original Message-----
>> > From: Stefano Garzarella [mailto:sgarzare@redhat.com]
>> > Sent: Thursday, May 13, 2021 5:42 PM
>> > To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
>> > <longpeng2@huawei.com>
>> > Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Gonglei
>> > (Arei) <arei.gonglei@huawei.com>; Subo (Subo, Cloud Infrastructure
>> > Service Product
>> > Dept.) <subo7@huawei.com>; David S . Miller <davem@davemloft.net>;
>> > Jakub Kicinski <kuba@kernel.org>; Jorgen Hansen <jhansen@vmware.com>;
>> > Norbert Slusarek <nslusarek@gmx.net>; Andra Paraschiv
>> > <andraprs@amazon.com>; Colin Ian King <colin.king@canonical.com>;
>> > David Brazdil <dbrazdil@google.com>; Alexander Popov
>> > <alex.popov@linux.com>; lixianming (E) <lixianming5@huawei.com>
>> > Subject: Re: [RFC] vsock: notify server to shutdown when client has
>> > pending signal
>> >
>> > Hi,
>> > thanks for this patch, comments below...
>> >
>> > On Tue, May 11, 2021 at 05:41:27PM +0800, Longpeng(Mike) wrote:
>> > >The client's sk_state will be set to TCP_ESTABLISHED if the server
>> > >replay the client's connect request.
>> > >However, if the client has pending signal, its sk_state will be set
>> > >to TCP_CLOSE without notify the server, so the server will hold the
>> > >corrupt connection.
>> > >
>> > >            client                        server
>> > >
>> > >1. sk_state=TCP_SYN_SENT         |
>> > >2. call ->connect()              |
>> > >3. wait reply                    |
>> > >                                 | 4. sk_state=TCP_ESTABLISHED
>> > >                                 | 5. insert to connected list
>> > >                                 | 6. reply to the client
>> > >7. sk_state=TCP_ESTABLISHED      |
>> > >8. insert to connected list      |
>> > >9. *signal pending* <--------------------- the user kill client
>> > >10. sk_state=TCP_CLOSE           |
>> > >client is exiting...             |
>> > >11. call ->release()             |
>> > >     virtio_transport_close
>> > >      if (!(sk->sk_state == TCP_ESTABLISHED ||
>> > >	      sk->sk_state == TCP_CLOSING))
>> > >		return true; <------------- return at here As a result, the server
>> > >cannot notice the connection is corrupt.
>> > >So the client should notify the peer in this case.
>> > >
>> > >Cc: David S. Miller <davem@davemloft.net>
>> > >Cc: Jakub Kicinski <kuba@kernel.org>
>> > >Cc: Stefano Garzarella <sgarzare@redhat.com>
>> > >Cc: Jorgen Hansen <jhansen@vmware.com>
>> > >Cc: Norbert Slusarek <nslusarek@gmx.net>
>> > >Cc: Andra Paraschiv <andraprs@amazon.com>
>> > >Cc: Colin Ian King <colin.king@canonical.com>
>> > >Cc: David Brazdil <dbrazdil@google.com>
>> > >Cc: Alexander Popov <alex.popov@linux.com>
>> > >Signed-off-by: lixianming <lixianming5@huawei.com>
>> > >Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
>> > >---
>> > > net/vmw_vsock/af_vsock.c | 1 +
>> > > 1 file changed, 1 insertion(+)
>> > >
>> > >diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>> > >index
>> > >92a72f0..d5df908 100644
>> > >--- a/net/vmw_vsock/af_vsock.c
>> > >+++ b/net/vmw_vsock/af_vsock.c
>> > >@@ -1368,6 +1368,7 @@ static int vsock_stream_connect(struct socket
>> > >*sock,
>> > struct sockaddr *addr,
>> > > 		lock_sock(sk);
>> > >
>> > > 		if (signal_pending(current)) {
>> > >+			vsock_send_shutdown(sk, SHUTDOWN_MASK);
>> >
>> > I see the issue, but I'm not sure is okay to send the shutdown in any
>> > case, think about the server didn't setup the connection.
>> >
>> > Maybe is better to set TCP_CLOSING if the socket state was
>> > TCP_ESTABLISHED, so the shutdown will be handled by the
>> > transport->release() as usual.
>> >
>> > What do you think?
>> >
>>
>> Your method looks more gracefully, we'll try it and get back to you, 
>> thanks.
>>
>
>As your suggestion, the following code can solve the problem:
>
>                if (signal_pending(current)) {
>                        err = sock_intr_errno(timeout);
>-                       sk->sk_state = TCP_CLOSE;
>+                       sk->sk_state = TCP_CLOSING;
>                        sock->state = SS_UNCONNECTED;
>                        vsock_transport_cancel_pkt(vsk);
>                        goto out_wait;
>
>This will send shutdown to the server even if the connection is not established, but
>I don't see any side effects yet, right ?

Should we set TCP_CLOSING only if sk_state was TCP_ESTABLISHED?

>
>The problem is also in the timeout case, we should fix it together ?
>

I'm not sure, if we reach the timeout, it should mean that the other 
peer never answered, so why take care to notify it?

Thanks,
Stefano