Add support for TCP send buffer auto tuning.

Send buffer size in TCP indicates the amount of bytes available for the sender
to transmit. This change will allow TCP to update the send buffer size when
- TCP enters established state.
- ACK is received.

The auto tuning is disabled when the send buffer size is set with the
SO_SNDBUF option.

PiperOrigin-RevId: 390312274

2 files changed, 8 insertions, 2 deletions

diff --git a/pkg/sentry/socket/unix/transport/connectioned.go b/pkg/sentry/socket/unix/transport/connectioned.go
index 33f9aeb06..9a398c3b5 100644
--- a/pkg/sentry/socket/unix/transport/connectioned.go
+++ b/pkg/sentry/socket/unix/transport/connectioned.go
@@ -129,9 +129,9 @@ func newConnectioned(ctx context.Context, stype linux.SockType, uid UniqueIDProv
 		stype:        stype,
 	}
 
+	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits, getReceiveBufferLimits)
 	ep.ops.SetSendBufferSize(defaultBufferSize, false /* notify */)
 	ep.ops.SetReceiveBufferSize(defaultBufferSize, false /* notify */)
-	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits, getReceiveBufferLimits)
 	return ep
 }
 
@@ -517,3 +517,6 @@ func (e *connectionedEndpoint) OnSetSendBufferSize(v int64) (newSz int64) {
 	}
 	return v
 }
+
+// WakeupWriters implements tcpip.SocketOptionsHandler.WakeupWriters.
+func (e *connectionedEndpoint) WakeupWriters() {}
diff --git a/pkg/sentry/socket/unix/transport/connectionless.go b/pkg/sentry/socket/unix/transport/connectionless.go
index 61338728a..61311718e 100644
--- a/pkg/sentry/socket/unix/transport/connectionless.go
+++ b/pkg/sentry/socket/unix/transport/connectionless.go
@@ -44,9 +44,9 @@ func NewConnectionless(ctx context.Context) Endpoint {
 	q := queue{ReaderQueue: ep.Queue, WriterQueue: &waiter.Queue{}, limit: defaultBufferSize}
 	q.InitRefs()
 	ep.receiver = &queueReceiver{readQueue: &q}
+	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits, getReceiveBufferLimits)
 	ep.ops.SetSendBufferSize(defaultBufferSize, false /* notify */)
 	ep.ops.SetReceiveBufferSize(defaultBufferSize, false /* notify */)
-	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits, getReceiveBufferLimits)
 	return ep
 }
 
@@ -227,3 +227,6 @@ func (e *connectionlessEndpoint) OnSetSendBufferSize(v int64) (newSz int64) {
 	}
 	return v
 }
+
+// WakeupWriters implements tcpip.SocketOptionsHandler.WakeupWriters.
+func (e *connectionlessEndpoint) WakeupWriters() {}