8 files changed, 125 insertions, 32 deletions
diff --git a/pkg/sentry/socket/unix/BUILD b/pkg/sentry/socket/unix/BUILD
index cce0acc33..acf2ab8e7 100644
--- a/pkg/sentry/socket/unix/BUILD
+++ b/pkg/sentry/socket/unix/BUILD
@@ -51,6 +51,7 @@ go_library(
         "//pkg/sentry/fs/fsutil",
         "//pkg/sentry/fs/lock",
         "//pkg/sentry/fsimpl/sockfs",
+        "//pkg/sentry/inet",
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/time",
         "//pkg/sentry/socket",
diff --git a/pkg/sentry/socket/unix/transport/BUILD b/pkg/sentry/socket/unix/transport/BUILD
index 3ebbd28b0..0d11bb251 100644
--- a/pkg/sentry/socket/unix/transport/BUILD
+++ b/pkg/sentry/socket/unix/transport/BUILD
@@ -32,6 +32,7 @@ go_library(
         "connectioned.go",
         "connectioned_state.go",
         "connectionless.go",
+        "connectionless_state.go",
         "queue.go",
         "queue_refs.go",
         "transport_message_list.go",
@@ -45,6 +46,7 @@ go_library(
         "//pkg/log",
         "//pkg/refs",
         "//pkg/refsvfs2",
+        "//pkg/sentry/inet",
         "//pkg/sync",
         "//pkg/syserr",
         "//pkg/tcpip",
diff --git a/pkg/sentry/socket/unix/transport/connectioned.go b/pkg/sentry/socket/unix/transport/connectioned.go
index fc5b823b0..809c95429 100644
--- a/pkg/sentry/socket/unix/transport/connectioned.go
+++ b/pkg/sentry/socket/unix/transport/connectioned.go
@@ -128,7 +128,9 @@ func newConnectioned(ctx context.Context, stype linux.SockType, uid UniqueIDProv
 		idGenerator:  uid,
 		stype:        stype,
 	}
-	ep.ops.InitHandler(ep, nil, nil)
+
+	ep.ops.SetSendBufferSize(defaultBufferSize, false /* notify */)
+	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits)
 	return ep
 }
 
@@ -137,9 +139,9 @@ func NewPair(ctx context.Context, stype linux.SockType, uid UniqueIDProvider) (E
 	a := newConnectioned(ctx, stype, uid)
 	b := newConnectioned(ctx, stype, uid)
 
-	q1 := &queue{ReaderQueue: a.Queue, WriterQueue: b.Queue, limit: initialLimit}
+	q1 := &queue{ReaderQueue: a.Queue, WriterQueue: b.Queue, limit: defaultBufferSize}
 	q1.InitRefs()
-	q2 := &queue{ReaderQueue: b.Queue, WriterQueue: a.Queue, limit: initialLimit}
+	q2 := &queue{ReaderQueue: b.Queue, WriterQueue: a.Queue, limit: defaultBufferSize}
 	q2.InitRefs()
 
 	if stype == linux.SOCK_STREAM {
@@ -173,7 +175,8 @@ func NewExternal(ctx context.Context, stype linux.SockType, uid UniqueIDProvider
 		idGenerator:  uid,
 		stype:        stype,
 	}
-	ep.ops.InitHandler(ep, nil, nil)
+	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits)
+	ep.ops.SetSendBufferSize(connected.SendMaxQueueSize(), false /* notify */)
 	return ep
 }
 
@@ -296,16 +299,18 @@ func (e *connectionedEndpoint) BidirectionalConnect(ctx context.Context, ce Conn
 		idGenerator: e.idGenerator,
 		stype:       e.stype,
 	}
-	ne.ops.InitHandler(ne, nil, nil)
+	ne.ops.InitHandler(ne, &stackHandler{}, getSendBufferLimits)
+	ne.ops.SetSendBufferSize(defaultBufferSize, false /* notify */)
 
-	readQueue := &queue{ReaderQueue: ce.WaiterQueue(), WriterQueue: ne.Queue, limit: initialLimit}
+	readQueue := &queue{ReaderQueue: ce.WaiterQueue(), WriterQueue: ne.Queue, limit: defaultBufferSize}
 	readQueue.InitRefs()
 	ne.connected = &connectedEndpoint{
 		endpoint:   ce,
 		writeQueue: readQueue,
 	}
 
-	writeQueue := &queue{ReaderQueue: ne.Queue, WriterQueue: ce.WaiterQueue(), limit: initialLimit}
+	// Make sure the accepted endpoint inherits this listening socket's SO_SNDBUF.
+	writeQueue := &queue{ReaderQueue: ne.Queue, WriterQueue: ce.WaiterQueue(), limit: e.ops.GetSendBufferSize()}
 	writeQueue.InitRefs()
 	if e.stype == linux.SOCK_STREAM {
 		ne.receiver = &streamQueueReceiver{queueReceiver: queueReceiver{readQueue: writeQueue}}
@@ -357,6 +362,9 @@ func (e *connectionedEndpoint) Connect(ctx context.Context, server BoundEndpoint
 	returnConnect := func(r Receiver, ce ConnectedEndpoint) {
 		e.receiver = r
 		e.connected = ce
+		// Make sure the newly created connected endpoint's write queue is updated
+		// to reflect this endpoint's send buffer size.
+		e.connected.SetSendBufferSize(e.ops.GetSendBufferSize())
 	}
 
 	return server.BidirectionalConnect(ctx, e, returnConnect)
@@ -495,3 +503,11 @@ func (e *connectionedEndpoint) State() uint32 {
 	}
 	return linux.SS_UNCONNECTED
 }
+
+// OnSetSendBufferSize implements tcpip.SocketOptionsHandler.OnSetSendBufferSize.
+func (e *connectionedEndpoint) OnSetSendBufferSize(v int64) (newSz int64) {
+	if e.Connected() {
+		return e.baseEndpoint.connected.SetSendBufferSize(v)
+	}
+	return v
+}
diff --git a/pkg/sentry/socket/unix/transport/connectioned_state.go b/pkg/sentry/socket/unix/transport/connectioned_state.go
index 7e02a5db8..590b0bd01 100644
--- a/pkg/sentry/socket/unix/transport/connectioned_state.go
+++ b/pkg/sentry/socket/unix/transport/connectioned_state.go
@@ -51,3 +51,8 @@ func (e *connectionedEndpoint) loadAcceptedChan(acceptedSlice []*connectionedEnd
 		}
 	}
 }
+
+// afterLoad is invoked by stateify.
+func (e *connectionedEndpoint) afterLoad() {
+	e.ops.InitHandler(e, &stackHandler{}, getSendBufferLimits)
+}
diff --git a/pkg/sentry/socket/unix/transport/connectionless.go b/pkg/sentry/socket/unix/transport/connectionless.go
index 20fa8b874..0be78480c 100644
--- a/pkg/sentry/socket/unix/transport/connectionless.go
+++ b/pkg/sentry/socket/unix/transport/connectionless.go
@@ -41,10 +41,11 @@ var (
 // NewConnectionless creates a new unbound dgram endpoint.
 func NewConnectionless(ctx context.Context) Endpoint {
 	ep := &connectionlessEndpoint{baseEndpoint{Queue: &waiter.Queue{}}}
-	q := queue{ReaderQueue: ep.Queue, WriterQueue: &waiter.Queue{}, limit: initialLimit}
+	q := queue{ReaderQueue: ep.Queue, WriterQueue: &waiter.Queue{}, limit: defaultBufferSize}
 	q.InitRefs()
 	ep.receiver = &queueReceiver{readQueue: &q}
-	ep.ops.InitHandler(ep, nil, nil)
+	ep.ops.SetSendBufferSize(defaultBufferSize, false /* notify */)
+	ep.ops.InitHandler(ep, &stackHandler{}, getSendBufferLimits)
 	return ep
 }
 
@@ -217,3 +218,11 @@ func (e *connectionlessEndpoint) State() uint32 {
 		return linux.SS_DISCONNECTING
 	}
 }
+
+// OnSetSendBufferSize implements tcpip.SocketOptionsHandler.OnSetSendBufferSize.
+func (e *connectionlessEndpoint) OnSetSendBufferSize(v int64) (newSz int64) {
+	if e.Connected() {
+		return e.baseEndpoint.connected.SetSendBufferSize(v)
+	}
+	return v
+}
diff --git a/pkg/sentry/socket/unix/transport/connectionless_state.go b/pkg/sentry/socket/unix/transport/connectionless_state.go
new file mode 100644
index 000000000..2ef337ec8
--- /dev/null
+++ b/pkg/sentry/socket/unix/transport/connectionless_state.go
@@ -0,0 +1,20 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package transport
+
+// afterLoad is invoked by stateify.
+func (e *connectionlessEndpoint) afterLoad() {
+	e.ops.InitHandler(e, &stackHandler{}, getSendBufferLimits)
+}
diff --git a/pkg/sentry/socket/unix/transport/queue.go b/pkg/sentry/socket/unix/transport/queue.go
index 342def28f..698a9a82c 100644
--- a/pkg/sentry/socket/unix/transport/queue.go
+++ b/pkg/sentry/socket/unix/transport/queue.go
@@ -237,9 +237,18 @@ func (q *queue) QueuedSize() int64 {
 
 // MaxQueueSize returns the maximum number of bytes storable in the queue.
 func (q *queue) MaxQueueSize() int64 {
+	q.mu.Lock()
+	defer q.mu.Unlock()
 	return q.limit
 }
 
+// SetMaxQueueSize sets the maximum number of bytes storable in the queue.
+func (q *queue) SetMaxQueueSize(v int64) {
+	q.mu.Lock()
+	defer q.mu.Unlock()
+	q.limit = v
+}
+
 // CloseUnread sets flag to indicate that the peer is closed (not shutdown)
 // with unread data. So if read on this queue shall return ECONNRESET error.
 func (q *queue) CloseUnread() {
diff --git a/pkg/sentry/socket/unix/transport/unix.go b/pkg/sentry/socket/unix/transport/unix.go
index 70227bbd2..ceada54a8 100644
--- a/pkg/sentry/socket/unix/transport/unix.go
+++ b/pkg/sentry/socket/unix/transport/unix.go
@@ -26,8 +26,16 @@ import (
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
-// initialLimit is the starting limit for the socket buffers.
-const initialLimit = 16 * 1024
+const (
+	// The minimum size of the send/receive buffers.
+	minimumBufferSize = 4 << 10 // 4 KiB (match default in linux)
+
+	// The default size of the send/receive buffers.
+	defaultBufferSize = 208 << 10 // 208 KiB  (default in linux for net.core.wmem_default)
+
+	// The maximum permitted size for the send/receive buffers.
+	maxBufferSize = 4 << 20 // 4 MiB 4 MiB (default in linux for net.core.wmem_max)
+)
 
 // A RightsControlMessage is a control message containing FDs.
 //
@@ -627,6 +635,10 @@ type ConnectedEndpoint interface {
 	// CloseUnread sets the fact that this end is closed with unread data to
 	// the peer socket.
 	CloseUnread()
+
+	// SetSendBufferSize is called when the endpoint's send buffer size is
+	// changed.
+	SetSendBufferSize(v int64) (newSz int64)
 }
 
 // +stateify savable
@@ -722,6 +734,14 @@ func (e *connectedEndpoint) CloseUnread() {
 	e.writeQueue.CloseUnread()
 }
 
+// SetSendBufferSize implements ConnectedEndpoint.SetSendBufferSize.
+// SetSendBufferSize sets the send buffer size for the write queue to the
+// specified value.
+func (e *connectedEndpoint) SetSendBufferSize(v int64) (newSz int64) {
+	e.writeQueue.SetMaxQueueSize(v)
+	return v
+}
+
 // baseEndpoint is an embeddable unix endpoint base used in both the connected and connectionless
 // unix domain socket Endpoint implementations.
 //
@@ -849,27 +869,6 @@ func (e *baseEndpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) tcpip.Error {
 	return nil
 }
 
-// IsUnixSocket implements tcpip.SocketOptionsHandler.IsUnixSocket.
-func (e *baseEndpoint) IsUnixSocket() bool {
-	return true
-}
-
-// GetSendBufferSize implements tcpip.SocketOptionsHandler.GetSendBufferSize.
-func (e *baseEndpoint) GetSendBufferSize() (int64, tcpip.Error) {
-	e.Lock()
-	defer e.Unlock()
-
-	if !e.Connected() {
-		return -1, &tcpip.ErrNotConnected{}
-	}
-
-	v := e.connected.SendMaxQueueSize()
-	if v < 0 {
-		return -1, &tcpip.ErrQueueSizeNotSupported{}
-	}
-	return v, nil
-}
-
 func (e *baseEndpoint) GetSockOptInt(opt tcpip.SockOptInt) (int, tcpip.Error) {
 	switch opt {
 	case tcpip.ReceiveQueueSizeOption:
@@ -987,3 +986,35 @@ func (e *baseEndpoint) GetRemoteAddress() (tcpip.FullAddress, tcpip.Error) {
 func (*baseEndpoint) Release(context.Context) {
 	// Binding a baseEndpoint doesn't take a reference.
 }
+
+// stackHandler is just a stub implementation of tcpip.StackHandler to provide
+// when initializing socketoptions.
+type stackHandler struct {
+}
+
+// Option implements tcpip.StackHandler.
+func (h *stackHandler) Option(option interface{}) tcpip.Error {
+	panic("unimplemented")
+}
+
+// TransportProtocolOption implements tcpip.StackHandler.
+func (h *stackHandler) TransportProtocolOption(proto tcpip.TransportProtocolNumber, option tcpip.GettableTransportProtocolOption) tcpip.Error {
+	panic("unimplemented")
+}
+
+// getSendBufferLimits implements tcpip.GetSendBufferLimits.
+//
+// AF_UNIX sockets buffer sizes are not tied to the networking stack/namespace
+// in linux but are bound by net.core.(wmem|rmem)_(max|default).
+//
+// In gVisor net.core sysctls today are not exposed or if exposed are currently
+// tied to the networking stack in use. This makes it complicated for AF_UNIX
+// when we are in a new namespace w/ no networking stack. As a result for now we
+// define default/max values here in the unix socket implementation itself.
+func getSendBufferLimits(tcpip.StackHandler) tcpip.SendBufferSizeOption {
+	return tcpip.SendBufferSizeOption{
+		Min:     minimumBufferSize,
+		Default: defaultBufferSize,
+		Max:     maxBufferSize,
+	}
+}