diff --git a/pkg/tcpip/buffer/view.go b/pkg/tcpip/buffer/view.go index 17e94c562..8d42cd066 100644 --- a/pkg/tcpip/buffer/view.go +++ b/pkg/tcpip/buffer/view.go @@ -15,6 +15,10 @@ // Package buffer provides the implementation of a buffer view. package buffer +import ( + "bytes" +) + // View is a slice of a buffer, with convenience methods. type View []byte @@ -45,6 +49,13 @@ func (v *View) CapLength(length int) { *v = (*v)[:length:length] } +// Reader returns a bytes.Reader for v. +func (v *View) Reader() bytes.Reader { + var r bytes.Reader + r.Reset(*v) + return r +} + // ToVectorisedView returns a VectorisedView containing the receiver. func (v View) ToVectorisedView() VectorisedView { return NewVectorisedView(len(v), []View{v}) @@ -162,3 +173,12 @@ func (vv *VectorisedView) AppendView(v View) { vv.views = append(vv.views, v) vv.size += len(v) } + +// Readers returns a bytes.Reader for each of vv's views. +func (vv *VectorisedView) Readers() []bytes.Reader { + readers := make([]bytes.Reader, 0, len(vv.views)) + for _, v := range vv.views { + readers = append(readers, v.Reader()) + } + return readers +} diff --git a/pkg/tcpip/header/BUILD b/pkg/tcpip/header/BUILD index 9da0d71f8..7094f3f0b 100644 --- a/pkg/tcpip/header/BUILD +++ b/pkg/tcpip/header/BUILD @@ -14,6 +14,7 @@ go_library( "interfaces.go", "ipv4.go", "ipv6.go", + "ipv6_extension_headers.go", "ipv6_fragment.go", "ndp_neighbor_advert.go", "ndp_neighbor_solicit.go", @@ -55,11 +56,13 @@ go_test( size = "small", srcs = [ "eth_test.go", + "ipv6_extension_headers_test.go", "ndp_test.go", ], library = ":header", deps = [ "//pkg/tcpip", + "//pkg/tcpip/buffer", "@com_github_google_go-cmp//cmp:go_default_library", ], ) diff --git a/pkg/tcpip/header/ipv6_extension_headers.go b/pkg/tcpip/header/ipv6_extension_headers.go new file mode 100644 index 000000000..b8866d4d2 --- /dev/null +++ b/pkg/tcpip/header/ipv6_extension_headers.go @@ -0,0 +1,344 @@ +// 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 header + +import ( + "bufio" + "encoding/binary" + "fmt" + "io" + + "gvisor.dev/gvisor/pkg/tcpip/buffer" +) + +// IPv6ExtensionHeaderIdentifier is an IPv6 extension header identifier. +type IPv6ExtensionHeaderIdentifier uint8 + +const ( + // IPv6RoutingExtHdrIdentifier is the header identifier of a Routing extension + // header, as per RFC 8200 section 4.4. + IPv6RoutingExtHdrIdentifier IPv6ExtensionHeaderIdentifier = 43 + + // IPv6FragmentExtHdrIdentifier is the header identifier of a Fragment + // extension header, as per RFC 8200 section 4.5. + IPv6FragmentExtHdrIdentifier IPv6ExtensionHeaderIdentifier = 44 + + // IPv6NoNextHeaderIdentifier is the header identifier used to signify the end + // of an IPv6 payload, as per RFC 8200 section 4.7. + IPv6NoNextHeaderIdentifier IPv6ExtensionHeaderIdentifier = 59 +) + +const ( + // ipv6RoutingExtHdrSegmentsLeftIdx is the index to the Segments Left field + // within an IPv6RoutingExtHdr. + ipv6RoutingExtHdrSegmentsLeftIdx = 1 + + // ipv6FragmentExtHdrFragmentOffsetOffset is the offset to the start of the + // Fragment Offset field within an IPv6FragmentExtHdr. + ipv6FragmentExtHdrFragmentOffsetOffset = 0 + + // ipv6FragmentExtHdrFragmentOffsetShift is the least significant bits to + // discard from the Fragment Offset. + ipv6FragmentExtHdrFragmentOffsetShift = 3 + + // ipv6FragmentExtHdrFlagsIdx is the index to the flags field within an + // IPv6FragmentExtHdr. + ipv6FragmentExtHdrFlagsIdx = 1 + + // ipv6FragmentExtHdrMFlagMask is the mask of the More (M) flag within the + // flags field of an IPv6FragmentExtHdr. + ipv6FragmentExtHdrMFlagMask = 1 + + // ipv6FragmentExtHdrIdentificationOffset is the offset to the Identification + // field within an IPv6FragmentExtHdr. + ipv6FragmentExtHdrIdentificationOffset = 2 + + // ipv6ExtHdrLenBytesPerUnit is the unit size of an extension header's length + // field. That is, given a Length field of 2, the extension header expects + // 16 bytes following the first 8 bytes (see ipv6ExtHdrLenBytesExcluded for + // details about the first 8 bytes' exclusion from the Length field). + ipv6ExtHdrLenBytesPerUnit = 8 + + // ipv6ExtHdrLenBytesExcluded is the number of bytes excluded from an + // extension header's Length field following the Length field. + // + // The Length field excludes the first 8 bytes, but the Next Header and Length + // field take up the first 2 of the 8 bytes so we expect (at minimum) 6 bytes + // after the Length field. + // + // This ensures that every extension header is at least 8 bytes. + ipv6ExtHdrLenBytesExcluded = 6 + + // IPv6FragmentExtHdrFragmentOffsetBytesPerUnit is the unit size of a Fragment + // extension header's Fragment Offset field. That is, given a Fragment Offset + // of 2, the extension header is indiciating that the fragment's payload + // starts at the 16th byte in the reassembled packet. + IPv6FragmentExtHdrFragmentOffsetBytesPerUnit = 8 +) + +// IPv6PayloadHeader is implemented by the various headers that can be found +// in an IPv6 payload. +// +// These headers include IPv6 extension headers or upper layer data. +type IPv6PayloadHeader interface { + isIPv6PayloadHeader() +} + +// IPv6RawPayloadHeader the remainder of an IPv6 payload after an iterator +// encounters a Next Header field it does not recognize as an IPv6 extension +// header. +type IPv6RawPayloadHeader struct { + Identifier IPv6ExtensionHeaderIdentifier + Buf buffer.VectorisedView +} + +// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader. +func (IPv6RawPayloadHeader) isIPv6PayloadHeader() {} + +// IPv6RoutingExtHdr is a buffer holding the Routing extension header specific +// data as outlined in RFC 8200 section 4.4. +type IPv6RoutingExtHdr []byte + +// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader. +func (IPv6RoutingExtHdr) isIPv6PayloadHeader() {} + +// SegmentsLeft returns the Segments Left field. +func (b IPv6RoutingExtHdr) SegmentsLeft() uint8 { + return b[ipv6RoutingExtHdrSegmentsLeftIdx] +} + +// IPv6FragmentExtHdr is a buffer holding the Fragment extension header specific +// data as outlined in RFC 8200 section 4.5. +// +// Note, the buffer does not include the Next Header and Reserved fields. +type IPv6FragmentExtHdr [6]byte + +// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader. +func (IPv6FragmentExtHdr) isIPv6PayloadHeader() {} + +// FragmentOffset returns the Fragment Offset field. +// +// This value indicates where the buffer following the Fragment extension header +// starts in the target (reassembled) packet. +func (b IPv6FragmentExtHdr) FragmentOffset() uint16 { + return binary.BigEndian.Uint16(b[ipv6FragmentExtHdrFragmentOffsetOffset:]) >> ipv6FragmentExtHdrFragmentOffsetShift +} + +// More returns the More (M) flag. +// +// This indicates whether any fragments are expected to succeed b. +func (b IPv6FragmentExtHdr) More() bool { + return b[ipv6FragmentExtHdrFlagsIdx]&ipv6FragmentExtHdrMFlagMask != 0 +} + +// ID returns the Identification field. +// +// This value is used to uniquely identify the packet, between a +// souce and destination. +func (b IPv6FragmentExtHdr) ID() uint32 { + return binary.BigEndian.Uint32(b[ipv6FragmentExtHdrIdentificationOffset:]) +} + +// IPv6PayloadIterator is an iterator over the contents of an IPv6 payload. +// +// The IPv6 payload may contain IPv6 extension headers before any upper layer +// data. +// +// Note, between when an IPv6PayloadIterator is obtained and last used, no +// changes to the payload may happen. Doing so may cause undefined and +// unexpected behaviour. It is fine to obtain an IPv6PayloadIterator, iterate +// over the first few headers then modify the backing payload so long as the +// IPv6PayloadIterator obtained before modification is no longer used. +type IPv6PayloadIterator struct { + // The identifier of the next header to parse. + nextHdrIdentifier IPv6ExtensionHeaderIdentifier + + // reader is an io.Reader over payload. + reader bufio.Reader + payload buffer.VectorisedView + + // Indicates to the iterator that it should return the remaining payload as a + // raw payload on the next call to Next. + forceRaw bool +} + +// MakeIPv6PayloadIterator returns an iterator over the IPv6 payload containing +// extension headers, or a raw payload if the payload cannot be parsed. +func MakeIPv6PayloadIterator(nextHdrIdentifier IPv6ExtensionHeaderIdentifier, payload buffer.VectorisedView, check bool) (IPv6PayloadIterator, error) { + readers := payload.Readers() + readerPs := make([]io.Reader, 0, len(readers)) + for i := range readers { + readerPs = append(readerPs, &readers[i]) + } + + // We need a buffer of size 1 for calls to bufio.Reader.ReadByte. + reader := *bufio.NewReaderSize(io.MultiReader(readerPs...), 1) + + it := IPv6PayloadIterator{ + nextHdrIdentifier: nextHdrIdentifier, + payload: payload.Clone(nil), + reader: reader, + } + + var err error + + if check { + for { + var done bool + if _, done, err = it.Next(); err != nil || done { + break + } + } + + // Reset it (and its underlying readers) before returning it. + for i := range readers { + readers[i].Seek(0, io.SeekStart) + } + reader.Reset(io.MultiReader(readerPs...)) + it = IPv6PayloadIterator{ + nextHdrIdentifier: nextHdrIdentifier, + payload: payload.Clone(nil), + reader: reader, + } + } + + return it, err +} + +// AsRawHeader returns the remaining payload of i as a raw header and +// completes the iterator. +// +// Calls to Next after calling AsRawHeader on i will indicate that the +// iterator is done. +func (i *IPv6PayloadIterator) AsRawHeader() IPv6RawPayloadHeader { + buf := i.payload + identifier := i.nextHdrIdentifier + + // Mark i as done. + *i = IPv6PayloadIterator{ + nextHdrIdentifier: IPv6NoNextHeaderIdentifier, + } + + return IPv6RawPayloadHeader{Identifier: identifier, Buf: buf} +} + +// Next returns the next item in the payload. +// +// If the next item is not a known IPv6 extension header, IPv6RawPayloadHeader +// will be returned with the remaining bytes and next header identifier. +// +// The return is of the format (header, done, error). done will be true when +// Next is unable to return anything because the iterator has reached the end of +// the payload, or an error occured. +func (i *IPv6PayloadIterator) Next() (IPv6PayloadHeader, bool, error) { + // We could be forced to return i as a raw header when the previous header was + // a fragment extension header as the data following the fragment extension + // header may not be complete. + if i.forceRaw { + return i.AsRawHeader(), false, nil + } + + // Is the header we are parsing a known extension header? + switch i.nextHdrIdentifier { + case IPv6RoutingExtHdrIdentifier: + nextHdrIdentifier, bytes, err := i.nextHeaderData(false /* fragmentHdr */, nil) + if err != nil { + return nil, true, err + } + + i.nextHdrIdentifier = nextHdrIdentifier + return IPv6RoutingExtHdr(bytes), false, nil + case IPv6FragmentExtHdrIdentifier: + var data [6]byte + // We ignore the returned bytes becauase we know the fragment extension + // header specific data will fit in data. + nextHdrIdentifier, _, err := i.nextHeaderData(true /* fragmentHdr */, data[:]) + if err != nil { + return nil, true, err + } + + fragmentExtHdr := IPv6FragmentExtHdr(data) + + // If the packet is a fragmented packet, do not attempt to parse + // anything after the fragment extension header as the data following + // the extension header may not be complete. + if fragmentExtHdr.More() || fragmentExtHdr.FragmentOffset() != 0 { + i.forceRaw = true + } + + i.nextHdrIdentifier = nextHdrIdentifier + return fragmentExtHdr, false, nil + case IPv6NoNextHeaderIdentifier: + // This indicates the end of the IPv6 payload. + return nil, true, nil + + default: + // The header we are parsing is not a known extension header. Return the + // raw payload. + return i.AsRawHeader(), false, nil + } +} + +// nextHeaderData returns the extension header's Next Header field and raw data. +// +// fragmentHdr indicates that the extension header being parsed is the Fragment +// extension header so the Length field should be ignored as it is Reserved +// for the Fragment extension header. +// +// If bytes is not nil, extension header specific data will be read into bytes +// if it has enough capacity. If bytes is provided but does not have enough +// capacity for the data, nextHeaderData will panic. +func (i *IPv6PayloadIterator) nextHeaderData(fragmentHdr bool, bytes []byte) (IPv6ExtensionHeaderIdentifier, []byte, error) { + // We ignore the number of bytes read because we know we will only ever read + // at max 1 bytes since rune has a length of 1. If we read 0 bytes, the Read + // would return io.EOF to indicate that io.Reader has reached the end of the + // payload. + nextHdrIdentifier, err := i.reader.ReadByte() + i.payload.TrimFront(1) + if err != nil { + return 0, nil, fmt.Errorf("error when reading the Next Header field for extension header with id = %d: %w", i.nextHdrIdentifier, err) + } + + var length uint8 + length, err = i.reader.ReadByte() + i.payload.TrimFront(1) + if err != nil { + var ret error + if fragmentHdr { + ret = fmt.Errorf("error when reading the Length field for extension header with id = %d: %w", i.nextHdrIdentifier, err) + } else { + ret = fmt.Errorf("error when reading the Reserved field for extension header with id = %d: %w", i.nextHdrIdentifier, err) + } + return 0, nil, ret + } + if fragmentHdr { + length = 0 + } + + bytesLen := int(length)*ipv6ExtHdrLenBytesPerUnit + ipv6ExtHdrLenBytesExcluded + if bytes == nil { + bytes = make([]byte, bytesLen) + } else if n := len(bytes); n < bytesLen { + panic(fmt.Sprintf("bytes only has space for %d bytes but need space for %d bytes (length = %d) for extension header with id = %d", n, bytesLen, length, i.nextHdrIdentifier)) + } + + n, err := io.ReadFull(&i.reader, bytes) + i.payload.TrimFront(n) + if err != nil { + return 0, nil, fmt.Errorf("read %d out of %d extension header data bytes (length = %d) for header with id = %d: %w", n, bytesLen, length, i.nextHdrIdentifier, err) + } + + return IPv6ExtensionHeaderIdentifier(nextHdrIdentifier), bytes, nil +} diff --git a/pkg/tcpip/header/ipv6_extension_headers_test.go b/pkg/tcpip/header/ipv6_extension_headers_test.go new file mode 100644 index 000000000..4bfdc77c4 --- /dev/null +++ b/pkg/tcpip/header/ipv6_extension_headers_test.go @@ -0,0 +1,515 @@ +// 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 header + +import ( + "bytes" + "errors" + "io" + "testing" + + "github.com/google/go-cmp/cmp" + "gvisor.dev/gvisor/pkg/tcpip/buffer" +) + +// Equal returns true of a and b are equivalent. +// +// Note, Equal will return true if a and b hold the same Identifier value and +// contain the same bytes in Buf, even if the bytes are split across views +// differently. +// +// Needed to use cmp.Equal on IPv6RawPayloadHeader as it contains unexported +// fields. +func (a IPv6RawPayloadHeader) Equal(b IPv6RawPayloadHeader) bool { + return a.Identifier == b.Identifier && bytes.Equal(a.Buf.ToView(), b.Buf.ToView()) +} + +func TestIPv6RoutingExtHdr(t *testing.T) { + tests := []struct { + name string + bytes []byte + segmentsLeft uint8 + }{ + { + name: "Zeroes", + bytes: []byte{0, 0, 0, 0, 0, 0}, + segmentsLeft: 0, + }, + { + name: "Ones", + bytes: []byte{1, 1, 1, 1, 1, 1}, + segmentsLeft: 1, + }, + { + name: "Mixed", + bytes: []byte{1, 2, 3, 4, 5, 6}, + segmentsLeft: 2, + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + extHdr := IPv6RoutingExtHdr(test.bytes) + if got := extHdr.SegmentsLeft(); got != test.segmentsLeft { + t.Errorf("got SegmentsLeft() = %d, want = %d", got, test.segmentsLeft) + } + }) + } +} + +func TestIPv6FragmentExtHdr(t *testing.T) { + tests := []struct { + name string + bytes [6]byte + fragmentOffset uint16 + more bool + id uint32 + }{ + { + name: "Zeroes", + bytes: [6]byte{0, 0, 0, 0, 0, 0}, + fragmentOffset: 0, + more: false, + id: 0, + }, + { + name: "Ones", + bytes: [6]byte{0, 9, 0, 0, 0, 1}, + fragmentOffset: 1, + more: true, + id: 1, + }, + { + name: "Mixed", + bytes: [6]byte{68, 9, 128, 4, 2, 1}, + fragmentOffset: 2177, + more: true, + id: 2147746305, + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + extHdr := IPv6FragmentExtHdr(test.bytes) + if got := extHdr.FragmentOffset(); got != test.fragmentOffset { + t.Errorf("got FragmentOffset() = %d, want = %d", got, test.fragmentOffset) + } + if got := extHdr.More(); got != test.more { + t.Errorf("got More() = %t, want = %t", got, test.more) + } + if got := extHdr.ID(); got != test.id { + t.Errorf("got ID() = %d, want = %d", got, test.id) + } + }) + } +} + +func makeVectorisedViewFromByteBuffers(bs ...[]byte) buffer.VectorisedView { + size := 0 + var vs []buffer.View + + for _, b := range bs { + vs = append(vs, buffer.View(b)) + size += len(b) + } + + return buffer.NewVectorisedView(size, vs) +} + +func TestIPv6ExtHdrIterErr(t *testing.T) { + tests := []struct { + name string + firstNextHdr IPv6ExtensionHeaderIdentifier + payload buffer.VectorisedView + err error + }{ + { + name: "Upper layer only without data", + firstNextHdr: 255, + }, + { + name: "Upper layer only with data", + firstNextHdr: 255, + payload: makeVectorisedViewFromByteBuffers([]byte{1, 2, 3, 4}), + }, + + { + name: "No next header", + firstNextHdr: IPv6NoNextHeaderIdentifier, + }, + { + name: "No next header with data", + firstNextHdr: IPv6NoNextHeaderIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{1, 2, 3, 4}), + }, + + { + name: "Valid single fragment", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 0, 68, 9, 128, 4, 2, 1}), + }, + { + name: "Fragment too small", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 0, 68, 9, 128, 4, 2}), + err: io.ErrUnexpectedEOF, + }, + + { + name: "Valid single routing", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 0, 1, 2, 3, 4, 5, 6}), + }, + { + name: "Valid single routing across views", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 0, 1, 2}, []byte{3, 4, 5, 6}), + }, + { + name: "Routing too small with zero length field", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 0, 1, 2, 3, 4, 5}), + err: io.ErrUnexpectedEOF, + }, + { + name: "Valid routing with non-zero length field", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 1, 1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6, 7, 8}), + }, + { + name: "Valid routing with non-zero length field across views", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 1, 1, 2, 3, 4, 5, 6}, []byte{1, 2, 3, 4, 5, 6, 7, 8}), + }, + { + name: "Routing too small with non-zero length field", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 1, 1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6, 7}), + err: io.ErrUnexpectedEOF, + }, + { + name: "Routing too small with non-zero length field across views", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{255, 1, 1, 2, 3, 4, 5, 6}, []byte{1, 2, 3, 4, 5, 6, 7}), + err: io.ErrUnexpectedEOF, + }, + + { + name: "Mixed", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Fragment extension header. + uint8(IPv6RoutingExtHdrIdentifier), 0, 68, 9, 128, 4, 2, 1, + + // Routing extension header. + 255, 0, 1, 2, 3, 4, 5, 6, + + // Upper layer data. + 1, 2, 3, 4, + }), + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + if _, err := MakeIPv6PayloadIterator(test.firstNextHdr, test.payload, false); err != nil { + t.Errorf("got MakeIPv6PayloadIterator(%d, _, false) = %s, want = nil", test.firstNextHdr, err) + } + + if _, err := MakeIPv6PayloadIterator(test.firstNextHdr, test.payload, true); !errors.Is(err, test.err) { + t.Errorf("got MakeIPv6PayloadIterator(%d, _, true) = %v, want = %v", test.firstNextHdr, err, test.err) + } + }) + } +} + +func TestIPv6ExtHdrIter(t *testing.T) { + routingExtHdrWithUpperLayerData := buffer.View([]byte{255, 0, 1, 2, 3, 4, 5, 6, 1, 2, 3, 4}) + upperLayerData := buffer.View([]byte{1, 2, 3, 4}) + tests := []struct { + name string + firstNextHdr IPv6ExtensionHeaderIdentifier + payload buffer.VectorisedView + expected []IPv6PayloadHeader + }{ + // With a non-atomic fragment, the payload after the fragment will not be + // parsed because the payload may not be complete. + { + name: "fragment - routing - upper", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Fragment extension header. + uint8(IPv6RoutingExtHdrIdentifier), 0, 68, 9, 128, 4, 2, 1, + + // Routing extension header. + 255, 0, 1, 2, 3, 4, 5, 6, + + // Upper layer data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6FragmentExtHdr([6]byte{68, 9, 128, 4, 2, 1}), + IPv6RawPayloadHeader{ + Identifier: IPv6RoutingExtHdrIdentifier, + Buf: routingExtHdrWithUpperLayerData.ToVectorisedView(), + }, + }, + }, + { + name: "fragment - routing - upper (across views)", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Fragment extension header. + uint8(IPv6RoutingExtHdrIdentifier), 0, 68, 9, 128, 4, 2, 1, + + // Routing extension header. + 255, 0, 1, 2}, []byte{3, 4, 5, 6, + + // Upper layer data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6FragmentExtHdr([6]byte{68, 9, 128, 4, 2, 1}), + IPv6RawPayloadHeader{ + Identifier: IPv6RoutingExtHdrIdentifier, + Buf: routingExtHdrWithUpperLayerData.ToVectorisedView(), + }, + }, + }, + + // If we have an atomic fragment, the payload following the fragment + // extension header should be parsed normally. + { + name: "atomic fragment - routing - upper", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Fragment extension header. + // + // Reserved bits are 1 which should not affect anything. + uint8(IPv6RoutingExtHdrIdentifier), 255, 0, 6, 128, 4, 2, 1, + + // Routing extension header. + 255, 0, 1, 2, 3, 4, 5, 6, + + // Upper layer data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6FragmentExtHdr([6]byte{0, 6, 128, 4, 2, 1}), + IPv6RoutingExtHdr([]byte{1, 2, 3, 4, 5, 6}), + IPv6RawPayloadHeader{ + Identifier: 255, + Buf: upperLayerData.ToVectorisedView(), + }, + }, + }, + { + name: "atomic fragment - routing - upper (across views)", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Fragment extension header. + // + // Reserved bits are 1 which should not affect anything. + uint8(IPv6RoutingExtHdrIdentifier), 255, 0, 6}, []byte{128, 4, 2, 1, + + // Routing extension header. + 255, 0, 1, 2}, []byte{3, 4, 5, 6, + + // Upper layer data. + 1, 2}, []byte{3, 4}), + expected: []IPv6PayloadHeader{ + IPv6FragmentExtHdr([6]byte{0, 6, 128, 4, 2, 1}), + IPv6RoutingExtHdr([]byte{1, 2, 3, 4, 5, 6}), + IPv6RawPayloadHeader{ + Identifier: 255, + Buf: makeVectorisedViewFromByteBuffers(upperLayerData[:2], upperLayerData[2:]), + }, + }, + }, + { + name: "atomic fragment - no next header", + firstNextHdr: IPv6FragmentExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Fragment extension header. + // + // Res (Reserved) bits are 1 which should not affect anything. + uint8(IPv6NoNextHeaderIdentifier), 0, 0, 6, 128, 4, 2, 1, + + // Random data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6FragmentExtHdr([6]byte{0, 6, 128, 4, 2, 1}), + }, + }, + { + name: "routing - atomic fragment - no next header", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Routing extension header. + uint8(IPv6FragmentExtHdrIdentifier), 0, 1, 2, 3, 4, 5, 6, + + // Fragment extension header. + // + // Reserved bits are 1 which should not affect anything. + uint8(IPv6NoNextHeaderIdentifier), 0, 0, 6, 128, 4, 2, 1, + + // Random data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6RoutingExtHdr([]byte{1, 2, 3, 4, 5, 6}), + IPv6FragmentExtHdr([6]byte{0, 6, 128, 4, 2, 1}), + }, + }, + { + name: "routing - atomic fragment - no next header (across views)", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Routing extension header. + uint8(IPv6FragmentExtHdrIdentifier), 0, 1, 2, 3, 4, 5, 6, + + // Fragment extension header. + // + // Reserved bits are 1 which should not affect anything. + uint8(IPv6NoNextHeaderIdentifier), 255, 0, 6}, []byte{128, 4, 2, 1, + + // Random data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6RoutingExtHdr([]byte{1, 2, 3, 4, 5, 6}), + IPv6FragmentExtHdr([6]byte{0, 6, 128, 4, 2, 1}), + }, + }, + { + name: "routing - fragment - no next header", + firstNextHdr: IPv6RoutingExtHdrIdentifier, + payload: makeVectorisedViewFromByteBuffers([]byte{ + // Routing extension header. + uint8(IPv6FragmentExtHdrIdentifier), 0, 1, 2, 3, 4, 5, 6, + + // Fragment extension header. + // + // Fragment Offset = 32; Res = 6. + uint8(IPv6NoNextHeaderIdentifier), 0, 1, 6, 128, 4, 2, 1, + + // Random data. + 1, 2, 3, 4, + }), + expected: []IPv6PayloadHeader{ + IPv6RoutingExtHdr([]byte{1, 2, 3, 4, 5, 6}), + IPv6FragmentExtHdr([6]byte{1, 6, 128, 4, 2, 1}), + IPv6RawPayloadHeader{ + Identifier: IPv6NoNextHeaderIdentifier, + Buf: upperLayerData.ToVectorisedView(), + }, + }, + }, + + // Test the raw payload for common transport layer protocol numbers. + { + name: "TCP raw payload", + firstNextHdr: IPv6ExtensionHeaderIdentifier(TCPProtocolNumber), + payload: makeVectorisedViewFromByteBuffers(upperLayerData), + expected: []IPv6PayloadHeader{IPv6RawPayloadHeader{ + Identifier: IPv6ExtensionHeaderIdentifier(TCPProtocolNumber), + Buf: upperLayerData.ToVectorisedView(), + }}, + }, + { + name: "UDP raw payload", + firstNextHdr: IPv6ExtensionHeaderIdentifier(UDPProtocolNumber), + payload: makeVectorisedViewFromByteBuffers(upperLayerData), + expected: []IPv6PayloadHeader{IPv6RawPayloadHeader{ + Identifier: IPv6ExtensionHeaderIdentifier(UDPProtocolNumber), + Buf: upperLayerData.ToVectorisedView(), + }}, + }, + { + name: "ICMPv4 raw payload", + firstNextHdr: IPv6ExtensionHeaderIdentifier(ICMPv4ProtocolNumber), + payload: makeVectorisedViewFromByteBuffers(upperLayerData), + expected: []IPv6PayloadHeader{IPv6RawPayloadHeader{ + Identifier: IPv6ExtensionHeaderIdentifier(ICMPv4ProtocolNumber), + Buf: upperLayerData.ToVectorisedView(), + }}, + }, + { + name: "ICMPv6 raw payload", + firstNextHdr: IPv6ExtensionHeaderIdentifier(ICMPv6ProtocolNumber), + payload: makeVectorisedViewFromByteBuffers(upperLayerData), + expected: []IPv6PayloadHeader{IPv6RawPayloadHeader{ + Identifier: IPv6ExtensionHeaderIdentifier(ICMPv6ProtocolNumber), + Buf: upperLayerData.ToVectorisedView(), + }}, + }, + { + name: "Unknwon next header raw payload", + firstNextHdr: 255, + payload: makeVectorisedViewFromByteBuffers(upperLayerData), + expected: []IPv6PayloadHeader{IPv6RawPayloadHeader{ + Identifier: 255, + Buf: upperLayerData.ToVectorisedView(), + }}, + }, + { + name: "Unknwon next header raw payload (across views)", + firstNextHdr: 255, + payload: makeVectorisedViewFromByteBuffers(upperLayerData[:2], upperLayerData[2:]), + expected: []IPv6PayloadHeader{IPv6RawPayloadHeader{ + Identifier: 255, + Buf: makeVectorisedViewFromByteBuffers(upperLayerData[:2], upperLayerData[2:]), + }}, + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + it, err := MakeIPv6PayloadIterator(test.firstNextHdr, test.payload, true) + if err != nil { + t.Fatalf("MakeIPv6PayloadIterator(%d, _ true): %s", test.firstNextHdr, err) + } + + for i, e := range test.expected { + extHdr, done, err := it.Next() + if err != nil { + t.Errorf("(i=%d) Next(): %s", i, err) + } + if done { + t.Errorf("(i=%d) unexpectedly done iterating", i) + } + if diff := cmp.Diff(e, extHdr); diff != "" { + t.Errorf("(i=%d) got ext hdr mismatch (-want +got):\n%s", i, diff) + } + + if t.Failed() { + t.FailNow() + } + } + + extHdr, done, err := it.Next() + if err != nil { + t.Errorf("(last) Next(): %s", err) + } + if !done { + t.Errorf("(last) iterator unexpectedly not done") + } + if extHdr != nil { + t.Errorf("(last) got Next() = %T, want = nil", extHdr) + } + }) + } +} diff --git a/pkg/tcpip/network/hash/hash.go b/pkg/tcpip/network/hash/hash.go index 6a215938b..8f65713c5 100644 --- a/pkg/tcpip/network/hash/hash.go +++ b/pkg/tcpip/network/hash/hash.go @@ -80,12 +80,12 @@ func IPv4FragmentHash(h header.IPv4) uint32 { // RFC 2640 (sec 4.5) is not very sharp on this aspect. // As a reference, also Linux ignores the protocol to compute // the hash (inet6_hash_frag). -func IPv6FragmentHash(h header.IPv6, f header.IPv6Fragment) uint32 { +func IPv6FragmentHash(h header.IPv6, id uint32) uint32 { t := h.SourceAddress() y := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24 t = h.DestinationAddress() z := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24 - return Hash3Words(f.ID(), y, z, hashIV) + return Hash3Words(id, y, z, hashIV) } func rol32(v, shift uint32) uint32 { diff --git a/pkg/tcpip/network/ipv6/BUILD b/pkg/tcpip/network/ipv6/BUILD index fb11874c6..a93a7621a 100644 --- a/pkg/tcpip/network/ipv6/BUILD +++ b/pkg/tcpip/network/ipv6/BUILD @@ -13,6 +13,8 @@ go_library( "//pkg/tcpip", "//pkg/tcpip/buffer", "//pkg/tcpip/header", + "//pkg/tcpip/network/fragmentation", + "//pkg/tcpip/network/hash", "//pkg/tcpip/stack", ], ) @@ -36,5 +38,6 @@ go_test( "//pkg/tcpip/transport/icmp", "//pkg/tcpip/transport/udp", "//pkg/waiter", + "@com_github_google_go-cmp//cmp:go_default_library", ], ) diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go index 29e597002..a703a768c 100644 --- a/pkg/tcpip/network/ipv6/ipv6.go +++ b/pkg/tcpip/network/ipv6/ipv6.go @@ -21,11 +21,14 @@ package ipv6 import ( + "fmt" "sync/atomic" "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/header" + "gvisor.dev/gvisor/pkg/tcpip/network/fragmentation" + "gvisor.dev/gvisor/pkg/tcpip/network/hash" "gvisor.dev/gvisor/pkg/tcpip/stack" ) @@ -49,6 +52,7 @@ type endpoint struct { linkEP stack.LinkEndpoint linkAddrCache stack.LinkAddressCache dispatcher stack.TransportDispatcher + fragmentation *fragmentation.Fragmentation protocol *protocol } @@ -172,6 +176,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) { headerView := pkt.Data.First() h := header.IPv6(headerView) if !h.IsValid(pkt.Data.Size()) { + r.Stats().IP.MalformedPacketsReceived.Increment() return } @@ -179,14 +184,120 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) { pkt.Data.TrimFront(header.IPv6MinimumSize) pkt.Data.CapLength(int(h.PayloadLength())) - p := h.TransportProtocol() - if p == header.ICMPv6ProtocolNumber { - e.handleICMP(r, headerView, pkt) + it, err := header.MakeIPv6PayloadIterator(header.IPv6ExtensionHeaderIdentifier(h.NextHeader()), pkt.Data, true) + if err != nil { + r.Stats().IP.MalformedPacketsReceived.Increment() return } - r.Stats().IP.PacketsDelivered.Increment() - e.dispatcher.DeliverTransportPacket(r, p, pkt) + for { + extHdr, done, err := it.Next() + if err != nil { + // This should never happen as MakeIPv6PayloadIterator above did not + // return an error. + panic(fmt.Sprintf("unexpected error when iterating over IPv6 payload: %s", err)) + } + if done { + break + } + + switch extHdr := extHdr.(type) { + case header.IPv6RoutingExtHdr: + // As per RFC 8200 section 4.4, if a node encounters a routing header with + // an unrecognized routing type value, with a non-zero Segments Left + // value, the node must discard the packet and send an ICMP Parameter + // Problem, Code 0. If the Segments Left is 0, the node must ignore the + // Routing extension header and process the next header in the packet. + // + // Note, the stack does not yet handle any type of routing extension + // header, so we just make sure Segments Left is zero before processing + // the next extension header. + // + // TODO(b/152019344): Send an ICMPv6 Parameter Problem Code 0 for + // unrecognized routing types with a non-zero Segments Left value. + if extHdr.SegmentsLeft() != 0 { + return + } + + case header.IPv6FragmentExtHdr: + fragmentOffset := extHdr.FragmentOffset() + more := extHdr.More() + if !more && fragmentOffset == 0 { + // This fragment extension header indicates that this packet is an + // atomic fragment. An atomic fragment is a fragment that contains + // all the data required to reassemble a full packet. As per RFC 6946, + // atomic fragments must not interfere with "normal" fragmented traffic + // so we skip processing the fragment instead of feeding it through the + // reassembly process below. + continue + } + + rawPayload := it.AsRawHeader() + fragmentPayloadLen := rawPayload.Buf.Size() + if fragmentPayloadLen == 0 { + // Drop the packet as it's marked as a fragment but has no payload. + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + + // The packet is a fragment, let's try to reassemble it. + start := fragmentOffset * header.IPv6FragmentExtHdrFragmentOffsetBytesPerUnit + last := start + uint16(fragmentPayloadLen) - 1 + + // Drop the packet if the fragmentOffset is incorrect. i.e the + // combination of fragmentOffset and pkt.Data.size() causes a + // wrap around resulting in last being less than the offset. + if last < start { + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + + var ready bool + pkt.Data, ready, err = e.fragmentation.Process(hash.IPv6FragmentHash(h, extHdr.ID()), start, last, more, rawPayload.Buf) + if err != nil { + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + + if ready { + // We create a new iterator with the reassembled packet because we could + // have more extension headers in the reassembled payload, as per RFC + // 8200 section 4.5. + it, err = header.MakeIPv6PayloadIterator(rawPayload.Identifier, pkt.Data, true) + if err != nil { + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + } + + case header.IPv6RawPayloadHeader: + // If the last header in the payload isn't a known IPv6 extension header, + // handle it as if it is transport layer data. + pkt.Data = extHdr.Buf + + if p := tcpip.TransportProtocolNumber(extHdr.Identifier); p == header.ICMPv6ProtocolNumber { + e.handleICMP(r, headerView, pkt) + } else { + r.Stats().IP.PacketsDelivered.Increment() + // TODO(b/152019344): Send an ICMPv6 Parameter Problem, Code 1 error + // in response to unrecognized next header values. + e.dispatcher.DeliverTransportPacket(r, p, pkt) + } + + default: + // If we receive a packet for an extension header we do not yet handle, + // drop the packet for now. + // + // TODO(b/152019344): Send an ICMPv6 Parameter Problem, Code 1 error + // in response to unrecognized next header values. + r.Stats().UnknownProtocolRcvdPackets.Increment() + return + } + } } // Close cleans up resources associated with the endpoint. @@ -229,6 +340,7 @@ func (p *protocol) NewEndpoint(nicID tcpip.NICID, addrWithPrefix tcpip.AddressWi linkEP: linkEP, linkAddrCache: linkAddrCache, dispatcher: dispatcher, + fragmentation: fragmentation.NewFragmentation(fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout), protocol: p, }, nil } diff --git a/pkg/tcpip/network/ipv6/ipv6_test.go b/pkg/tcpip/network/ipv6/ipv6_test.go index ed98ef22a..86bfda85e 100644 --- a/pkg/tcpip/network/ipv6/ipv6_test.go +++ b/pkg/tcpip/network/ipv6/ipv6_test.go @@ -17,6 +17,7 @@ package ipv6 import ( "testing" + "github.com/google/go-cmp/cmp" "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/header" @@ -33,6 +34,12 @@ const ( // The least significant 3 bytes are the same as addr2 so both addr2 and // addr3 will have the same solicited-node address. addr3 = "\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x02" + + // Tests use the extension header identifier values as uint8 instead of + // header.IPv6ExtensionHeaderIdentifier. + routingExtHdrID = uint8(header.IPv6RoutingExtHdrIdentifier) + fragmentExtHdrID = uint8(header.IPv6FragmentExtHdrIdentifier) + noNextHdrID = uint8(header.IPv6NoNextHeaderIdentifier) ) // testReceiveICMP tests receiving an ICMP packet from src to dst. want is the @@ -268,3 +275,764 @@ func TestAddIpv6Address(t *testing.T) { }) } } + +func TestReceiveIPv6ExtHdrs(t *testing.T) { + const nicID = 1 + + tests := []struct { + name string + extHdr func(nextHdr uint8) ([]byte, uint8) + shouldAccept bool + }{ + { + name: "None", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{}, nextHdr }, + shouldAccept: true, + }, + { + name: "routing with zero segments left", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{nextHdr, 0, 1, 0, 2, 3, 4, 5}, routingExtHdrID }, + shouldAccept: true, + }, + { + name: "routing with non-zero segments left", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{nextHdr, 0, 1, 1, 2, 3, 4, 5}, routingExtHdrID }, + shouldAccept: false, + }, + { + name: "atomic fragment with zero ID", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{nextHdr, 0, 0, 0, 0, 0, 0, 0}, fragmentExtHdrID }, + shouldAccept: true, + }, + { + name: "atomic fragment with non-zero ID", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{nextHdr, 0, 0, 0, 1, 2, 3, 4}, fragmentExtHdrID }, + shouldAccept: true, + }, + { + name: "fragment", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{nextHdr, 0, 1, 0, 1, 2, 3, 4}, fragmentExtHdrID }, + shouldAccept: false, + }, + { + name: "routing - atomic fragment", + extHdr: func(nextHdr uint8) ([]byte, uint8) { + return []byte{ + // Routing extension header. + fragmentExtHdrID, 0, 1, 0, 2, 3, 4, 5, + + // Fragment extension header. + nextHdr, 0, 0, 0, 1, 2, 3, 4, + }, routingExtHdrID + }, + shouldAccept: true, + }, + { + name: "atomic fragment - routing", + extHdr: func(nextHdr uint8) ([]byte, uint8) { + return []byte{ + // Fragment extension header. + routingExtHdrID, 0, 0, 0, 1, 2, 3, 4, + + // Routing extension header. + nextHdr, 0, 1, 0, 2, 3, 4, 5, + }, fragmentExtHdrID + }, + shouldAccept: true, + }, + { + name: "No next header", + extHdr: func(nextHdr uint8) ([]byte, uint8) { return []byte{}, noNextHdrID }, + shouldAccept: false, + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + s := stack.New(stack.Options{ + NetworkProtocols: []stack.NetworkProtocol{NewProtocol()}, + TransportProtocols: []stack.TransportProtocol{udp.NewProtocol()}, + }) + e := channel.New(0, 1280, linkAddr1) + if err := s.CreateNIC(nicID, e); err != nil { + t.Fatalf("CreateNIC(%d, _) = %s", nicID, err) + } + if err := s.AddAddress(nicID, ProtocolNumber, addr2); err != nil { + t.Fatalf("AddAddress(%d, %d, %s) = %s", nicID, ProtocolNumber, addr2, err) + } + + wq := waiter.Queue{} + we, ch := waiter.NewChannelEntry(nil) + wq.EventRegister(&we, waiter.EventIn) + defer wq.EventUnregister(&we) + defer close(ch) + ep, err := s.NewEndpoint(udp.ProtocolNumber, ProtocolNumber, &wq) + if err != nil { + t.Fatalf("NewEndpoint(%d, %d, _): %s", udp.ProtocolNumber, ProtocolNumber, err) + } + defer ep.Close() + + bindAddr := tcpip.FullAddress{Addr: addr2, Port: 80} + if err := ep.Bind(bindAddr); err != nil { + t.Fatalf("Bind(%+v): %s", bindAddr, err) + } + + udpPayload := []byte{1, 2, 3, 4, 5, 6, 7, 8} + udpLength := header.UDPMinimumSize + len(udpPayload) + extHdrBytes, ipv6NextHdr := test.extHdr(uint8(header.UDPProtocolNumber)) + extHdrLen := len(extHdrBytes) + hdr := buffer.NewPrependable(header.IPv6MinimumSize + extHdrLen + udpLength) + + // Serialize UDP message. + u := header.UDP(hdr.Prepend(udpLength)) + u.Encode(&header.UDPFields{ + SrcPort: 5555, + DstPort: 80, + Length: uint16(udpLength), + }) + copy(u.Payload(), udpPayload) + sum := header.PseudoHeaderChecksum(udp.ProtocolNumber, addr1, addr2, uint16(udpLength)) + sum = header.Checksum(udpPayload, sum) + u.SetChecksum(^u.CalculateChecksum(sum)) + + // Copy extension header bytes between the UDP message and the IPv6 + // fixed header. + copy(hdr.Prepend(extHdrLen), extHdrBytes) + + // Serialize IPv6 fixed header. + payloadLength := hdr.UsedLength() + ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize)) + ip.Encode(&header.IPv6Fields{ + PayloadLength: uint16(payloadLength), + NextHeader: ipv6NextHdr, + HopLimit: 255, + SrcAddr: addr1, + DstAddr: addr2, + }) + + e.InjectInbound(ProtocolNumber, stack.PacketBuffer{ + Data: hdr.View().ToVectorisedView(), + }) + + stats := s.Stats().UDP.PacketsReceived + + if !test.shouldAccept { + if got := stats.Value(); got != 0 { + t.Errorf("got UDP Rx Packets = %d, want = 0", got) + } + + return + } + + // Expect a UDP packet. + if got := stats.Value(); got != 1 { + t.Errorf("got UDP Rx Packets = %d, want = 1", got) + } + gotPayload, _, err := ep.Read(nil) + if err != nil { + t.Fatalf("Read(nil): %s", err) + } + if diff := cmp.Diff(buffer.View(udpPayload), gotPayload); diff != "" { + t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff) + } + + // Should not have any more UDP packets. + if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock { + t.Fatalf("got Read(nil) = (%x, _, %v), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock) + } + }) + } +} + +// fragmentData holds the IPv6 payload for a fragmented IPv6 packet. +type fragmentData struct { + nextHdr uint8 + data buffer.VectorisedView +} + +func TestReceiveIPv6Fragments(t *testing.T) { + const nicID = 1 + const udpPayload1Length = 256 + const udpPayload2Length = 128 + const fragmentExtHdrLen = 8 + // Note, not all routing extension headers will be 8 bytes but this test + // uses 8 byte routing extension headers for most sub tests. + const routingExtHdrLen = 8 + + udpGen := func(payload []byte, multiplier uint8) buffer.View { + payloadLen := len(payload) + for i := 0; i < payloadLen; i++ { + payload[i] = uint8(i) * multiplier + } + + udpLength := header.UDPMinimumSize + payloadLen + + hdr := buffer.NewPrependable(udpLength) + u := header.UDP(hdr.Prepend(udpLength)) + u.Encode(&header.UDPFields{ + SrcPort: 5555, + DstPort: 80, + Length: uint16(udpLength), + }) + copy(u.Payload(), payload) + sum := header.PseudoHeaderChecksum(udp.ProtocolNumber, addr1, addr2, uint16(udpLength)) + sum = header.Checksum(payload, sum) + u.SetChecksum(^u.CalculateChecksum(sum)) + return hdr.View() + } + + var udpPayload1Buf [udpPayload1Length]byte + udpPayload1 := udpPayload1Buf[:] + ipv6Payload1 := udpGen(udpPayload1, 1) + + var udpPayload2Buf [udpPayload2Length]byte + udpPayload2 := udpPayload2Buf[:] + ipv6Payload2 := udpGen(udpPayload2, 2) + + tests := []struct { + name string + expectedPayload []byte + fragments []fragmentData + expectedPayloads [][]byte + }{ + { + name: "No fragmentation", + fragments: []fragmentData{ + { + nextHdr: uint8(header.UDPProtocolNumber), + data: ipv6Payload1.ToVectorisedView(), + }, + }, + expectedPayloads: [][]byte{udpPayload1}, + }, + { + name: "Atomic fragment", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1), + []buffer.View{ + // Fragment extension header. + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 0, 0, 0, 0, 0}), + + ipv6Payload1, + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload1}, + }, + { + name: "Two fragments", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 1}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 8, More = false, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 64, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload1}, + }, + { + name: "Two fragments with different IDs", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 1}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 8, More = false, ID = 2 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 64, 0, 0, 0, 2}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: nil, + }, + { + name: "Two fragments with per-fragment routing header with zero segments left", + fragments: []fragmentData{ + { + nextHdr: routingExtHdrID, + data: buffer.NewVectorisedView( + routingExtHdrLen+fragmentExtHdrLen+64, + []buffer.View{ + // Routing extension header. + // + // Segments left = 0. + buffer.View([]byte{fragmentExtHdrID, 0, 1, 0, 2, 3, 4, 5}), + + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 1}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: routingExtHdrID, + data: buffer.NewVectorisedView( + routingExtHdrLen+fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Routing extension header. + // + // Segments left = 0. + buffer.View([]byte{fragmentExtHdrID, 0, 1, 0, 2, 3, 4, 5}), + + // Fragment extension header. + // + // Fragment offset = 8, More = false, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 64, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload1}, + }, + { + name: "Two fragments with per-fragment routing header with non-zero segments left", + fragments: []fragmentData{ + { + nextHdr: routingExtHdrID, + data: buffer.NewVectorisedView( + routingExtHdrLen+fragmentExtHdrLen+64, + []buffer.View{ + // Routing extension header. + // + // Segments left = 1. + buffer.View([]byte{fragmentExtHdrID, 0, 1, 1, 2, 3, 4, 5}), + + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 1}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: routingExtHdrID, + data: buffer.NewVectorisedView( + routingExtHdrLen+fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Routing extension header. + // + // Segments left = 1. + buffer.View([]byte{fragmentExtHdrID, 0, 1, 1, 2, 3, 4, 5}), + + // Fragment extension header. + // + // Fragment offset = 9, More = false, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 72, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: nil, + }, + { + name: "Two fragments with routing header with zero segments left", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + routingExtHdrLen+fragmentExtHdrLen+64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 1, 0, 0, 0, 1}), + + // Routing extension header. + // + // Segments left = 0. + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 1, 0, 2, 3, 4, 5}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 9, More = false, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 72, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload1}, + }, + { + name: "Two fragments with routing header with non-zero segments left", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + routingExtHdrLen+fragmentExtHdrLen+64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 1, 0, 0, 0, 1}), + + // Routing extension header. + // + // Segments left = 1. + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 1, 1, 2, 3, 4, 5}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 9, More = false, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 72, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: nil, + }, + { + name: "Two fragments with routing header with zero segments left across fragments", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + // The length of this payload is fragmentExtHdrLen+8 because the + // first 8 bytes of the 16 byte routing extension header is in + // this fragment. + fragmentExtHdrLen+8, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 1, 0, 0, 0, 1}), + + // Routing extension header (part 1) + // + // Segments left = 0. + buffer.View([]byte{uint8(header.UDPProtocolNumber), 1, 1, 0, 2, 3, 4, 5}), + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + // The length of this payload is + // fragmentExtHdrLen+8+len(ipv6Payload1) because the last 8 bytes of + // the 16 byte routing extension header is in this fagment. + fragmentExtHdrLen+8+len(ipv6Payload1), + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 1, More = false, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 8, 0, 0, 0, 1}), + + // Routing extension header (part 2) + buffer.View([]byte{6, 7, 8, 9, 10, 11, 12, 13}), + + ipv6Payload1, + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload1}, + }, + { + name: "Two fragments with routing header with non-zero segments left across fragments", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + // The length of this payload is fragmentExtHdrLen+8 because the + // first 8 bytes of the 16 byte routing extension header is in + // this fragment. + fragmentExtHdrLen+8, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 1, 0, 0, 0, 1}), + + // Routing extension header (part 1) + // + // Segments left = 1. + buffer.View([]byte{uint8(header.UDPProtocolNumber), 1, 1, 1, 2, 3, 4, 5}), + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + // The length of this payload is + // fragmentExtHdrLen+8+len(ipv6Payload1) because the last 8 bytes of + // the 16 byte routing extension header is in this fagment. + fragmentExtHdrLen+8+len(ipv6Payload1), + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 1, More = false, ID = 1 + buffer.View([]byte{routingExtHdrID, 0, 0, 8, 0, 0, 0, 1}), + + // Routing extension header (part 2) + buffer.View([]byte{6, 7, 8, 9, 10, 11, 12, 13}), + + ipv6Payload1, + }, + ), + }, + }, + expectedPayloads: nil, + }, + // As per RFC 6946, IPv6 atomic fragments MUST NOT interfere with "normal" + // fragmented traffic. + { + name: "Two fragments with atomic", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 1}), + + ipv6Payload1[:64], + }, + ), + }, + // This fragment has the same ID as the other fragments but is an atomic + // fragment. It should not interfere with the other fragments. + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload2), + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = false, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 0, 0, 0, 0, 1}), + + ipv6Payload2, + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 8, More = false, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 64, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload2, udpPayload1}, + }, + { + name: "Two interleaved fragmented packets", + fragments: []fragmentData{ + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 1}), + + ipv6Payload1[:64], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+32, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 0, More = true, ID = 2 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 1, 0, 0, 0, 2}), + + ipv6Payload2[:32], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload1)-64, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 8, More = false, ID = 1 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 64, 0, 0, 0, 1}), + + ipv6Payload1[64:], + }, + ), + }, + { + nextHdr: fragmentExtHdrID, + data: buffer.NewVectorisedView( + fragmentExtHdrLen+len(ipv6Payload2)-32, + []buffer.View{ + // Fragment extension header. + // + // Fragment offset = 4, More = false, ID = 2 + buffer.View([]byte{uint8(header.UDPProtocolNumber), 0, 0, 32, 0, 0, 0, 2}), + + ipv6Payload2[32:], + }, + ), + }, + }, + expectedPayloads: [][]byte{udpPayload1, udpPayload2}, + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + s := stack.New(stack.Options{ + NetworkProtocols: []stack.NetworkProtocol{NewProtocol()}, + TransportProtocols: []stack.TransportProtocol{udp.NewProtocol()}, + }) + e := channel.New(0, 1280, linkAddr1) + if err := s.CreateNIC(nicID, e); err != nil { + t.Fatalf("CreateNIC(%d, _) = %s", nicID, err) + } + if err := s.AddAddress(nicID, ProtocolNumber, addr2); err != nil { + t.Fatalf("AddAddress(%d, %d, %s) = %s", nicID, ProtocolNumber, addr2, err) + } + + wq := waiter.Queue{} + we, ch := waiter.NewChannelEntry(nil) + wq.EventRegister(&we, waiter.EventIn) + defer wq.EventUnregister(&we) + defer close(ch) + ep, err := s.NewEndpoint(udp.ProtocolNumber, ProtocolNumber, &wq) + if err != nil { + t.Fatalf("NewEndpoint(%d, %d, _): %s", udp.ProtocolNumber, ProtocolNumber, err) + } + defer ep.Close() + + bindAddr := tcpip.FullAddress{Addr: addr2, Port: 80} + if err := ep.Bind(bindAddr); err != nil { + t.Fatalf("Bind(%+v): %s", bindAddr, err) + } + + for _, f := range test.fragments { + hdr := buffer.NewPrependable(header.IPv6MinimumSize) + + // Serialize IPv6 fixed header. + ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize)) + ip.Encode(&header.IPv6Fields{ + PayloadLength: uint16(f.data.Size()), + NextHeader: f.nextHdr, + HopLimit: 255, + SrcAddr: addr1, + DstAddr: addr2, + }) + + vv := hdr.View().ToVectorisedView() + vv.Append(f.data) + + e.InjectInbound(ProtocolNumber, stack.PacketBuffer{ + Data: vv, + }) + } + + if got, want := s.Stats().UDP.PacketsReceived.Value(), uint64(len(test.expectedPayloads)); got != want { + t.Errorf("got UDP Rx Packets = %d, want = %d", got, want) + } + + for i, p := range test.expectedPayloads { + gotPayload, _, err := ep.Read(nil) + if err != nil { + t.Fatalf("(i=%d) Read(nil): %s", i, err) + } + if diff := cmp.Diff(buffer.View(p), gotPayload); diff != "" { + t.Errorf("(i=%d) got UDP payload mismatch (-want +got):\n%s", i, diff) + } + } + + if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock { + t.Fatalf("(last) got Read(nil) = (%x, _, %v), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock) + } + }) + } +}