From fb9a649f39dc6f6a6accbf26db30a21fcc4bcf23 Mon Sep 17 00:00:00 2001 From: Bhasker Hariharan Date: Tue, 17 Nov 2020 08:30:31 -0800 Subject: Fix SO_ERROR behavior for TCP in gVisor. Fixes the behaviour of SO_ERROR for tcp sockets where in linux it returns sk->sk_err and if sk->sk_err is 0 then it returns sk->sk_soft_err. In gVisor TCP we endpoint.HardError is the equivalent of sk->sk_err and endpoint.LastError holds soft errors. This change brings this into alignment with Linux such that both hard/soft errors are cleared when retrieved using getsockopt(.. SO_ERROR) is called on a socket. Fixes #3812 PiperOrigin-RevId: 342868552 --- pkg/tcpip/transport/tcp/connect.go | 13 ++++----- pkg/tcpip/transport/tcp/endpoint.go | 47 +++++++++++++++++++++++-------- pkg/tcpip/transport/tcp/endpoint_state.go | 10 +++---- pkg/tcpip/transport/tcp/tcp_test.go | 14 ++++----- 4 files changed, 51 insertions(+), 33 deletions(-) (limited to 'pkg/tcpip/transport/tcp') diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index ac6d879a7..6661e8915 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -496,7 +496,7 @@ func (h *handshake) resolveRoute() *tcpip.Error { h.ep.mu.Lock() } if n¬ifyError != 0 { - return h.ep.LastError() + return h.ep.lastErrorLocked() } } @@ -575,7 +575,6 @@ func (h *handshake) complete() *tcpip.Error { return err } defer timer.stop() - for h.state != handshakeCompleted { // Unlock before blocking, and reacquire again afterwards (h.ep.mu is held // throughout handshake processing). @@ -631,9 +630,8 @@ func (h *handshake) complete() *tcpip.Error { h.ep.mu.Lock() } if n¬ifyError != 0 { - return h.ep.LastError() + return h.ep.lastErrorLocked() } - case wakerForNewSegment: if err := h.processSegments(); err != nil { return err @@ -1002,7 +1000,7 @@ func (e *endpoint) resetConnectionLocked(err *tcpip.Error) { // Only send a reset if the connection is being aborted for a reason // other than receiving a reset. e.setEndpointState(StateError) - e.HardError = err + e.hardError = err if err != tcpip.ErrConnectionReset && err != tcpip.ErrTimeout { // The exact sequence number to be used for the RST is the same as the // one used by Linux. We need to handle the case of window being shrunk @@ -1141,7 +1139,7 @@ func (e *endpoint) handleReset(s *segment) (ok bool, err *tcpip.Error) { // delete the TCB, and return. case StateCloseWait: e.transitionToStateCloseLocked() - e.HardError = tcpip.ErrAborted + e.hardError = tcpip.ErrAborted e.notifyProtocolGoroutine(notifyTickleWorker) return false, nil default: @@ -1353,7 +1351,6 @@ func (e *endpoint) protocolMainLoop(handshake bool, wakerInitDone chan<- struct{ epilogue := func() { // e.mu is expected to be hold upon entering this section. - if e.snd != nil { e.snd.resendTimer.cleanup() } @@ -1383,7 +1380,7 @@ func (e *endpoint) protocolMainLoop(handshake bool, wakerInitDone chan<- struct{ e.lastErrorMu.Unlock() e.setEndpointState(StateError) - e.HardError = err + e.hardError = err e.workerCleanup = true // Lock released below. diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go index 4f4f4c65e..a2161e49d 100644 --- a/pkg/tcpip/transport/tcp/endpoint.go +++ b/pkg/tcpip/transport/tcp/endpoint.go @@ -315,11 +315,6 @@ func (*Stats) IsEndpointStats() {} // +stateify savable type EndpointInfo struct { stack.TransportEndpointInfo - - // HardError is meaningful only when state is stateError. It stores the - // error to be returned when read/write syscalls are called and the - // endpoint is in this state. HardError is protected by endpoint mu. - HardError *tcpip.Error `state:".(string)"` } // IsEndpointInfo is an empty method to implement the tcpip.EndpointInfo @@ -386,6 +381,11 @@ type endpoint struct { waiterQueue *waiter.Queue `state:"wait"` uniqueID uint64 + // hardError is meaningful only when state is stateError. It stores the + // error to be returned when read/write syscalls are called and the + // endpoint is in this state. hardError is protected by endpoint mu. + hardError *tcpip.Error `state:".(string)"` + // lastError represents the last error that the endpoint reported; // access to it is protected by the following mutex. lastErrorMu sync.Mutex `state:"nosave"` @@ -1283,7 +1283,15 @@ func (e *endpoint) SetOwner(owner tcpip.PacketOwner) { e.owner = owner } -func (e *endpoint) LastError() *tcpip.Error { +// Preconditions: e.mu must be held to call this function. +func (e *endpoint) hardErrorLocked() *tcpip.Error { + err := e.hardError + e.hardError = nil + return err +} + +// Preconditions: e.mu must be held to call this function. +func (e *endpoint) lastErrorLocked() *tcpip.Error { e.lastErrorMu.Lock() defer e.lastErrorMu.Unlock() err := e.lastError @@ -1291,6 +1299,15 @@ func (e *endpoint) LastError() *tcpip.Error { return err } +func (e *endpoint) LastError() *tcpip.Error { + e.LockUser() + defer e.UnlockUser() + if err := e.hardErrorLocked(); err != nil { + return err + } + return e.lastErrorLocked() +} + // Read reads data from the endpoint. func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) { e.LockUser() @@ -1312,9 +1329,8 @@ func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, bufUsed := e.rcvBufUsed if s := e.EndpointState(); !s.connected() && s != StateClose && bufUsed == 0 { e.rcvListMu.Unlock() - he := e.HardError if s == StateError { - return buffer.View{}, tcpip.ControlMessages{}, he + return buffer.View{}, tcpip.ControlMessages{}, e.hardErrorLocked() } e.stats.ReadErrors.NotConnected.Increment() return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrNotConnected @@ -1370,9 +1386,13 @@ func (e *endpoint) readLocked() (buffer.View, *tcpip.Error) { // indicating the reason why it's not writable. // Caller must hold e.mu and e.sndBufMu func (e *endpoint) isEndpointWritableLocked() (int, *tcpip.Error) { + // The endpoint cannot be written to if it's not connected. switch s := e.EndpointState(); { case s == StateError: - return 0, e.HardError + if err := e.hardErrorLocked(); err != nil { + return 0, err + } + return 0, tcpip.ErrClosedForSend case !s.connecting() && !s.connected(): return 0, tcpip.ErrClosedForSend case s.connecting(): @@ -1486,7 +1506,7 @@ func (e *endpoint) Peek(vec [][]byte) (int64, tcpip.ControlMessages, *tcpip.Erro // but has some pending unread data. if s := e.EndpointState(); !s.connected() && s != StateClose { if s == StateError { - return 0, tcpip.ControlMessages{}, e.HardError + return 0, tcpip.ControlMessages{}, e.hardErrorLocked() } e.stats.ReadErrors.InvalidEndpointState.Increment() return 0, tcpip.ControlMessages{}, tcpip.ErrInvalidEndpointState @@ -2243,7 +2263,10 @@ func (e *endpoint) connect(addr tcpip.FullAddress, handshake bool, run bool) *tc return tcpip.ErrAlreadyConnecting case StateError: - return e.HardError + if err := e.hardErrorLocked(); err != nil { + return err + } + return tcpip.ErrConnectionAborted default: return tcpip.ErrInvalidEndpointState @@ -2417,7 +2440,7 @@ func (e *endpoint) startMainLoop(handshake bool) *tcpip.Error { e.lastErrorMu.Unlock() e.setEndpointState(StateError) - e.HardError = err + e.hardError = err // Call cleanupLocked to free up any reservations. e.cleanupLocked() diff --git a/pkg/tcpip/transport/tcp/endpoint_state.go b/pkg/tcpip/transport/tcp/endpoint_state.go index bb901c0f8..ba67176b5 100644 --- a/pkg/tcpip/transport/tcp/endpoint_state.go +++ b/pkg/tcpip/transport/tcp/endpoint_state.go @@ -321,21 +321,21 @@ func (e *endpoint) loadRecentTSTime(unix unixTime) { } // saveHardError is invoked by stateify. -func (e *EndpointInfo) saveHardError() string { - if e.HardError == nil { +func (e *endpoint) saveHardError() string { + if e.hardError == nil { return "" } - return e.HardError.String() + return e.hardError.String() } // loadHardError is invoked by stateify. -func (e *EndpointInfo) loadHardError(s string) { +func (e *endpoint) loadHardError(s string) { if s == "" { return } - e.HardError = tcpip.StringToError(s) + e.hardError = tcpip.StringToError(s) } // saveMeasureTime is invoked by stateify. diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go index 9f0fb41e3..c366a4cbc 100644 --- a/pkg/tcpip/transport/tcp/tcp_test.go +++ b/pkg/tcpip/transport/tcp/tcp_test.go @@ -75,9 +75,6 @@ func TestGiveUpConnect(t *testing.T) { // Wait for ep to become writable. <-notifyCh - if err := ep.LastError(); err != tcpip.ErrAborted { - t.Fatalf("got ep.LastError() = %s, want = %s", err, tcpip.ErrAborted) - } // Call Connect again to retreive the handshake failure status // and stats updates. @@ -3198,6 +3195,11 @@ loop: case tcpip.ErrWouldBlock: select { case <-ch: + // Expect the state to be StateError and subsequent Reads to fail with HardError. + if _, _, err := c.EP.Read(nil); err != tcpip.ErrConnectionReset { + t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrConnectionReset) + } + break loop case <-time.After(1 * time.Second): t.Fatalf("Timed out waiting for reset to arrive") } @@ -3207,14 +3209,10 @@ loop: t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrConnectionReset) } } - // Expect the state to be StateError and subsequent Reads to fail with HardError. - if _, _, err := c.EP.Read(nil); err != tcpip.ErrConnectionReset { - t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrConnectionReset) - } + if tcp.EndpointState(c.EP.State()) != tcp.StateError { t.Fatalf("got EP state is not StateError") } - if got := c.Stack().Stats().TCP.EstablishedResets.Value(); got != 1 { t.Errorf("got stats.TCP.EstablishedResets.Value() = %d, want = 1", got) } -- cgit v1.2.3