diff options
Diffstat (limited to 'pkg')
| -rw-r--r-- | pkg/tcpip/transport/tcp/accept.go | 14 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/connect.go | 60 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/rcv.go | 2 |
3 files changed, 65 insertions, 11 deletions
diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go index f24b51b91..023045ec1 100644 --- a/pkg/tcpip/transport/tcp/accept.go +++ b/pkg/tcpip/transport/tcp/accept.go @@ -419,8 +419,8 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) { // TODO(b/143300739): Use the userMSS of the listening socket // for accepted sockets. - switch s.flags { - case header.TCPFlagSyn: + switch { + case s.flags == header.TCPFlagSyn: opts := parseSynSegmentOptions(s) if incSynRcvdCount() { // Only handle the syn if the following conditions hold @@ -464,7 +464,7 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) { e.stack.Stats().TCP.ListenOverflowSynCookieSent.Increment() } - case header.TCPFlagAck: + case (s.flags & header.TCPFlagAck) != 0: if e.acceptQueueIsFull() { // Silently drop the ack as the application can't accept // the connection at this point. The ack will be @@ -478,6 +478,14 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) { } if !synCookiesInUse() { + // When not using SYN cookies, as per RFC 793, section 3.9, page 64: + // Any acknowledgment is bad if it arrives on a connection still in + // the LISTEN state. An acceptable reset segment should be formed + // for any arriving ACK-bearing segment. The RST should be + // formatted as follows: + // + // <SEQ=SEG.ACK><CTL=RST> + // // Send a reset as this is an ACK for which there is no // half open connections and we are not using cookies // yet. diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 49f2b9685..364067731 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -865,6 +865,33 @@ func (e *endpoint) completeWorkerLocked() { } } +// transitionToStateCloseLocked ensures that the endpoint is +// cleaned up from the transport demuxer, "before" moving to +// StateClose. This will ensure that no packet will be +// delivered to this endpoint from the demuxer when the endpoint +// is transitioned to StateClose. +func (e *endpoint) transitionToStateCloseLocked() { + if e.state == StateClose { + return + } + e.cleanupLocked() + e.state = StateClose +} + +// tryDeliverSegmentFromClosedEndpoint attempts to deliver the parsed +// segment to any other endpoint other than the current one. This is called +// only when the endpoint is in StateClose and we want to deliver the segment +// to any other listening endpoint. We reply with RST if we cannot find one. +func (e *endpoint) tryDeliverSegmentFromClosedEndpoint(s *segment) { + ep := e.stack.FindTransportEndpoint(e.NetProto, e.TransProto, e.ID, &s.route) + if ep == nil { + replyWithReset(s) + s.decRef() + return + } + ep.(*endpoint).enqueueSegment(s) +} + func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { if e.rcv.acceptable(s.sequenceNumber, 0) { // RFC 793, page 37 states that "in all states @@ -894,12 +921,8 @@ func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { // general "connection reset" signal. Enter the CLOSED state, // delete the TCB, and return. case StateCloseWait: - e.state = StateClose + e.transitionToStateCloseLocked() e.HardError = tcpip.ErrAborted - // We need to set this explicitly here because otherwise - // the port registrations will not be released till the - // endpoint is actively closed by the application. - e.workerCleanup = true e.mu.Unlock() return false, nil default: @@ -915,6 +938,20 @@ func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { func (e *endpoint) handleSegments() *tcpip.Error { checkRequeue := true for i := 0; i < maxSegmentsPerWake; i++ { + e.mu.RLock() + state := e.state + e.mu.RUnlock() + if state == StateClose { + // When we get into StateClose while processing from the queue, + // return immediately and let the protocolMainloop handle it. + // + // We can reach StateClose only while processing a previous segment + // or a notification from the protocolMainLoop (caller goroutine). + // This means that with this return, the segment dequeue below can + // never occur on a closed endpoint. + return nil + } + s := e.segmentQueue.dequeue() if s == nil { checkRequeue = false @@ -1160,7 +1197,7 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { // to the TCP_FIN_WAIT2 timeout was hit. Just // mark the socket as closed. e.mu.Lock() - e.state = StateClose + e.transitionToStateCloseLocked() e.mu.Unlock() return nil }, @@ -1321,12 +1358,21 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error { if e.state != StateError { e.stack.Stats().TCP.EstablishedResets.Increment() e.stack.Stats().TCP.CurrentEstablished.Decrement() - e.state = StateClose + e.transitionToStateCloseLocked() } // Lock released below. epilogue() + // epilogue removes the endpoint from the transport-demuxer and + // unlocks e.mu. Now that no new segments can get enqueued to this + // endpoint, try to re-match the segment to a different endpoint + // as the current endpoint is closed. + for !e.segmentQueue.empty() { + s := e.segmentQueue.dequeue() + e.tryDeliverSegmentFromClosedEndpoint(s) + } + // A new SYN was received during TIME_WAIT and we need to abort // the timewait and redirect the segment to the listener queue if reuseTW != nil { diff --git a/pkg/tcpip/transport/tcp/rcv.go b/pkg/tcpip/transport/tcp/rcv.go index 068b90fb6..857dc445f 100644 --- a/pkg/tcpip/transport/tcp/rcv.go +++ b/pkg/tcpip/transport/tcp/rcv.go @@ -218,7 +218,7 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum case StateClosing: r.ep.state = StateTimeWait case StateLastAck: - r.ep.state = StateClose + r.ep.transitionToStateCloseLocked() } r.ep.mu.Unlock() } |