diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp')
| -rw-r--r-- | pkg/tcpip/transport/tcp/BUILD | 10 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/accept.go | 14 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/connect.go | 15 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/endpoint.go | 13 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/rcv.go | 23 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/rcv_test.go | 74 |
6 files changed, 122 insertions, 27 deletions
diff --git a/pkg/tcpip/transport/tcp/BUILD b/pkg/tcpip/transport/tcp/BUILD index edb7718a6..61426623c 100644 --- a/pkg/tcpip/transport/tcp/BUILD +++ b/pkg/tcpip/transport/tcp/BUILD @@ -109,3 +109,13 @@ go_test( "//runsc/testutil", ], ) + +go_test( + name = "rcv_test", + size = "small", + srcs = ["rcv_test.go"], + deps = [ + ":tcp", + "//pkg/tcpip/seqnum", + ], +) diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go index 5bb243e3b..e6a23c978 100644 --- a/pkg/tcpip/transport/tcp/accept.go +++ b/pkg/tcpip/transport/tcp/accept.go @@ -101,7 +101,7 @@ type listenContext struct { // v6Only is true if listenEP is a dual stack socket and has the // IPV6_V6ONLY option set. - v6only bool + v6Only bool // netProto indicates the network protocol(IPv4/v6) for the listening // endpoint. @@ -126,12 +126,12 @@ func timeStamp() uint32 { } // newListenContext creates a new listen context. -func newListenContext(stk *stack.Stack, listenEP *endpoint, rcvWnd seqnum.Size, v6only bool, netProto tcpip.NetworkProtocolNumber) *listenContext { +func newListenContext(stk *stack.Stack, listenEP *endpoint, rcvWnd seqnum.Size, v6Only bool, netProto tcpip.NetworkProtocolNumber) *listenContext { l := &listenContext{ stack: stk, rcvWnd: rcvWnd, hasher: sha1.New(), - v6only: v6only, + v6Only: v6Only, netProto: netProto, listenEP: listenEP, pendingEndpoints: make(map[stack.TransportEndpointID]*endpoint), @@ -207,7 +207,7 @@ func (l *listenContext) createConnectingEndpoint(s *segment, iss seqnum.Value, i netProto = s.route.NetProto } n := newEndpoint(l.stack, netProto, queue) - n.v6only = l.v6only + n.v6only = l.v6Only n.ID = s.id n.boundNICID = s.route.NICID() n.route = s.route.Clone() @@ -293,7 +293,7 @@ func (l *listenContext) createEndpointAndPerformHandshake(s *segment, opts *head } // Perform the 3-way handshake. - h := newPassiveHandshake(ep, seqnum.Size(ep.initialReceiveWindow()), isn, irs, opts, deferAccept) + h := newPassiveHandshake(ep, ep.rcv.rcvWnd, isn, irs, opts, deferAccept) if err := h.execute(); err != nil { ep.mu.Unlock() ep.Close() @@ -613,8 +613,8 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) { // its own goroutine and is responsible for handling connection requests. func (e *endpoint) protocolListenLoop(rcvWnd seqnum.Size) *tcpip.Error { e.mu.Lock() - v6only := e.v6only - ctx := newListenContext(e.stack, e, rcvWnd, v6only, e.NetProto) + v6Only := e.v6only + ctx := newListenContext(e.stack, e, rcvWnd, v6Only, e.NetProto) defer func() { // Mark endpoint as closed. This will prevent goroutines running diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 368865911..76e27bf26 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -105,24 +105,11 @@ type handshake struct { } func newHandshake(ep *endpoint, rcvWnd seqnum.Size) handshake { - rcvWndScale := ep.rcvWndScaleForHandshake() - - // Round-down the rcvWnd to a multiple of wndScale. This ensures that the - // window offered in SYN won't be reduced due to the loss of precision if - // window scaling is enabled after the handshake. - rcvWnd = (rcvWnd >> uint8(rcvWndScale)) << uint8(rcvWndScale) - - // Ensure we can always accept at least 1 byte if the scale specified - // was too high for the provided rcvWnd. - if rcvWnd == 0 { - rcvWnd = 1 - } - h := handshake{ ep: ep, active: true, rcvWnd: rcvWnd, - rcvWndScale: int(rcvWndScale), + rcvWndScale: ep.rcvWndScaleForHandshake(), } h.resetState() return h diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go index 7e8def82d..45f2aa78b 100644 --- a/pkg/tcpip/transport/tcp/endpoint.go +++ b/pkg/tcpip/transport/tcp/endpoint.go @@ -1062,6 +1062,19 @@ func (e *endpoint) initialReceiveWindow() int { if rcvWnd > routeWnd { rcvWnd = routeWnd } + rcvWndScale := e.rcvWndScaleForHandshake() + + // Round-down the rcvWnd to a multiple of wndScale. This ensures that the + // window offered in SYN won't be reduced due to the loss of precision if + // window scaling is enabled after the handshake. + rcvWnd = (rcvWnd >> uint8(rcvWndScale)) << uint8(rcvWndScale) + + // Ensure we can always accept at least 1 byte if the scale specified + // was too high for the provided rcvWnd. + if rcvWnd == 0 { + rcvWnd = 1 + } + return rcvWnd } diff --git a/pkg/tcpip/transport/tcp/rcv.go b/pkg/tcpip/transport/tcp/rcv.go index caf8977b3..a4b73b588 100644 --- a/pkg/tcpip/transport/tcp/rcv.go +++ b/pkg/tcpip/transport/tcp/rcv.go @@ -70,13 +70,24 @@ func newReceiver(ep *endpoint, irs seqnum.Value, rcvWnd seqnum.Size, rcvWndScale // acceptable checks if the segment sequence number range is acceptable // according to the table on page 26 of RFC 793. func (r *receiver) acceptable(segSeq seqnum.Value, segLen seqnum.Size) bool { - rcvWnd := r.rcvNxt.Size(r.rcvAcc) - if rcvWnd == 0 { - return segLen == 0 && segSeq == r.rcvNxt - } + return Acceptable(segSeq, segLen, r.rcvNxt, r.rcvAcc) +} - return segSeq.InWindow(r.rcvNxt, rcvWnd) || - seqnum.Overlap(r.rcvNxt, rcvWnd, segSeq, segLen) +// Acceptable checks if a segment that starts at segSeq and has length segLen is +// "acceptable" for arriving in a receive window that starts at rcvNxt and ends +// before rcvAcc, according to the table on page 26 and 69 of RFC 793. +func Acceptable(segSeq seqnum.Value, segLen seqnum.Size, rcvNxt, rcvAcc seqnum.Value) bool { + if rcvNxt == rcvAcc { + return segLen == 0 && segSeq == rcvNxt + } + if segLen == 0 { + // rcvWnd is incremented by 1 because that is Linux's behavior despite the + // RFC. + return segSeq.InRange(rcvNxt, rcvAcc.Add(1)) + } + // Page 70 of RFC 793 allows packets that can be made "acceptable" by trimming + // the payload, so we'll accept any payload that overlaps the receieve window. + return rcvNxt.LessThan(segSeq.Add(segLen)) && segSeq.LessThan(rcvAcc) } // getSendParams returns the parameters needed by the sender when building diff --git a/pkg/tcpip/transport/tcp/rcv_test.go b/pkg/tcpip/transport/tcp/rcv_test.go new file mode 100644 index 000000000..dc02729ce --- /dev/null +++ b/pkg/tcpip/transport/tcp/rcv_test.go @@ -0,0 +1,74 @@ +// Copyright 2020 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 rcv_test + +import ( + "testing" + + "gvisor.dev/gvisor/pkg/tcpip/seqnum" + "gvisor.dev/gvisor/pkg/tcpip/transport/tcp" +) + +func TestAcceptable(t *testing.T) { + for _, tt := range []struct { + segSeq seqnum.Value + segLen seqnum.Size + rcvNxt, rcvAcc seqnum.Value + want bool + }{ + // The segment is smaller than the window. + {105, 2, 100, 104, false}, + {105, 2, 101, 105, false}, + {105, 2, 102, 106, true}, + {105, 2, 103, 107, true}, + {105, 2, 104, 108, true}, + {105, 2, 105, 109, true}, + {105, 2, 106, 110, true}, + {105, 2, 107, 111, false}, + + // The segment is larger than the window. + {105, 4, 103, 105, false}, + {105, 4, 104, 106, true}, + {105, 4, 105, 107, true}, + {105, 4, 106, 108, true}, + {105, 4, 107, 109, true}, + {105, 4, 108, 110, true}, + {105, 4, 109, 111, false}, + {105, 4, 110, 112, false}, + + // The segment has no width. + {105, 0, 100, 102, false}, + {105, 0, 101, 103, false}, + {105, 0, 102, 104, false}, + {105, 0, 103, 105, true}, + {105, 0, 104, 106, true}, + {105, 0, 105, 107, true}, + {105, 0, 106, 108, false}, + {105, 0, 107, 109, false}, + + // The receive window has no width. + {105, 2, 103, 103, false}, + {105, 2, 104, 104, false}, + {105, 2, 105, 105, false}, + {105, 2, 106, 106, false}, + {105, 2, 107, 107, false}, + {105, 2, 108, 108, false}, + {105, 2, 109, 109, false}, + } { + if got := tcp.Acceptable(tt.segSeq, tt.segLen, tt.rcvNxt, tt.rcvAcc); got != tt.want { + t.Errorf("tcp.Acceptable(%d, %d, %d, %d) = %t, want %t", tt.segSeq, tt.segLen, tt.rcvNxt, tt.rcvAcc, got, tt.want) + } + } +} |