diff options
| -rwxr-xr-x | pkg/tcpip/header/ndp_options.go | 196 | ||||
| -rwxr-xr-x | pkg/tcpip/header/ndpoptionidentifier_string.go | 50 | ||||
| -rwxr-xr-x | pkg/tcpip/stack/ndp.go | 3 |
3 files changed, 163 insertions, 86 deletions
diff --git a/pkg/tcpip/header/ndp_options.go b/pkg/tcpip/header/ndp_options.go index e6a6ad39b..444e90820 100755 --- a/pkg/tcpip/header/ndp_options.go +++ b/pkg/tcpip/header/ndp_options.go @@ -15,32 +15,43 @@ package header import ( + "bytes" "encoding/binary" "errors" "fmt" + "io" "math" "time" "gvisor.dev/gvisor/pkg/tcpip" ) +// NDPOptionIdentifier is an NDP option type identifier. +type NDPOptionIdentifier uint8 + const ( // NDPSourceLinkLayerAddressOptionType is the type of the Source Link Layer // Address option, as per RFC 4861 section 4.6.1. - NDPSourceLinkLayerAddressOptionType = 1 + NDPSourceLinkLayerAddressOptionType NDPOptionIdentifier = 1 // NDPTargetLinkLayerAddressOptionType is the type of the Target Link Layer // Address option, as per RFC 4861 section 4.6.1. - NDPTargetLinkLayerAddressOptionType = 2 + NDPTargetLinkLayerAddressOptionType NDPOptionIdentifier = 2 + + // NDPPrefixInformationType is the type of the Prefix Information + // option, as per RFC 4861 section 4.6.2. + NDPPrefixInformationType NDPOptionIdentifier = 3 + + // NDPRecursiveDNSServerOptionType is the type of the Recursive DNS + // Server option, as per RFC 8106 section 5.1. + NDPRecursiveDNSServerOptionType NDPOptionIdentifier = 25 +) +const ( // NDPLinkLayerAddressSize is the size of a Source or Target Link Layer // Address option for an Ethernet address. NDPLinkLayerAddressSize = 8 - // NDPPrefixInformationType is the type of the Prefix Information - // option, as per RFC 4861 section 4.6.2. - NDPPrefixInformationType = 3 - // ndpPrefixInformationLength is the expected length, in bytes, of the // body of an NDP Prefix Information option, as per RFC 4861 section // 4.6.2 which specifies that the Length field is 4. Given this, the @@ -91,10 +102,6 @@ const ( // within an NDPPrefixInformation. ndpPrefixInformationPrefixOffset = 14 - // NDPRecursiveDNSServerOptionType is the type of the Recursive DNS - // Server option, as per RFC 8106 section 5.1. - NDPRecursiveDNSServerOptionType = 25 - // ndpRecursiveDNSServerLifetimeOffset is the start of the 4-byte // Lifetime field within an NDPRecursiveDNSServer. ndpRecursiveDNSServerLifetimeOffset = 2 @@ -103,10 +110,10 @@ const ( // for IPv6 Recursive DNS Servers within an NDPRecursiveDNSServer. ndpRecursiveDNSServerAddressesOffset = 6 - // minNDPRecursiveDNSServerLength is the minimum NDP Recursive DNS - // Server option's length field value when it contains at least one - // IPv6 address. - minNDPRecursiveDNSServerLength = 3 + // minNDPRecursiveDNSServerLength is the minimum NDP Recursive DNS Server + // option's body size when it contains at least one IPv6 address, as per + // RFC 8106 section 5.3.1. + minNDPRecursiveDNSServerBodySize = 22 // lengthByteUnits is the multiplier factor for the Length field of an // NDP option. That is, the length field for NDP options is in units of @@ -132,16 +139,13 @@ var ( // few NDPOption then modify the backing NDPOptions so long as the // NDPOptionIterator obtained before modification is no longer used. type NDPOptionIterator struct { - // The NDPOptions this NDPOptionIterator is iterating over. - opts NDPOptions + opts *bytes.Buffer } // Potential errors when iterating over an NDPOptions. var ( - ErrNDPOptBufExhausted = errors.New("Buffer unexpectedly exhausted") - ErrNDPOptZeroLength = errors.New("NDP option has zero-valued Length field") - ErrNDPOptMalformedBody = errors.New("NDP option has a malformed body") - ErrNDPInvalidLength = errors.New("NDP option's Length value is invalid as per relevant RFC") + ErrNDPOptMalformedBody = errors.New("NDP option has a malformed body") + ErrNDPOptMalformedHeader = errors.New("NDP option has a malformed header") ) // Next returns the next element in the backing NDPOptions, or true if we are @@ -152,48 +156,50 @@ var ( func (i *NDPOptionIterator) Next() (NDPOption, bool, error) { for { // Do we still have elements to look at? - if len(i.opts) == 0 { + if i.opts.Len() == 0 { return nil, true, nil } - // Do we have enough bytes for an NDP option that has a Length - // field of at least 1? Note, 0 in the Length field is invalid. - if len(i.opts) < lengthByteUnits { - return nil, true, ErrNDPOptBufExhausted - } - // Get the Type field. - t := i.opts[0] - - // Get the Length field. - l := i.opts[1] + temp, err := i.opts.ReadByte() + if err != nil { + if err != io.EOF { + // ReadByte should only ever return nil or io.EOF. + panic(fmt.Sprintf("unexpected error when reading the option's Type field: %s", err)) + } - // This would indicate an erroneous NDP option as the Length - // field should never be 0. - if l == 0 { - return nil, true, ErrNDPOptZeroLength + // We use io.ErrUnexpectedEOF as exhausting the buffer is unexpected once + // we start parsing an option; we expect the buffer to contain enough + // bytes for the whole option. + return nil, true, fmt.Errorf("unexpectedly exhausted buffer when reading the option's Type field: %w", io.ErrUnexpectedEOF) } + kind := NDPOptionIdentifier(temp) - // How many bytes are in the option body? - numBytes := int(l) * lengthByteUnits - numBodyBytes := numBytes - 2 - - potentialBody := i.opts[2:] + // Get the Length field. + length, err := i.opts.ReadByte() + if err != nil { + if err != io.EOF { + panic(fmt.Sprintf("unexpected error when reading the option's Length field for %s: %s", kind, err)) + } - // This would indicate an erroenous NDPOptions buffer as we ran - // out of the buffer in the middle of an NDP option. - if left := len(potentialBody); left < numBodyBytes { - return nil, true, ErrNDPOptBufExhausted + return nil, true, fmt.Errorf("unexpectedly exhausted buffer when reading the option's Length field for %s: %w", kind, io.ErrUnexpectedEOF) } - // Get only the options body, leaving the rest of the options - // buffer alone. - body := potentialBody[:numBodyBytes] + // This would indicate an erroneous NDP option as the Length field should + // never be 0. + if length == 0 { + return nil, true, fmt.Errorf("zero valued Length field for %s: %w", kind, ErrNDPOptMalformedHeader) + } - // Update opts with the remaining options body. - i.opts = i.opts[numBytes:] + // Get the body. + numBytes := int(length) * lengthByteUnits + numBodyBytes := numBytes - 2 + body := i.opts.Next(numBodyBytes) + if len(body) < numBodyBytes { + return nil, true, fmt.Errorf("unexpectedly exhausted buffer when reading the option's Body for %s: %w", kind, io.ErrUnexpectedEOF) + } - switch t { + switch kind { case NDPSourceLinkLayerAddressOptionType: return NDPSourceLinkLayerAddressOption(body), false, nil @@ -205,22 +211,15 @@ func (i *NDPOptionIterator) Next() (NDPOption, bool, error) { // body is ndpPrefixInformationLength, as per RFC 4861 // section 4.6.2. if numBodyBytes != ndpPrefixInformationLength { - return nil, true, ErrNDPOptMalformedBody + return nil, true, fmt.Errorf("got %d bytes for NDP Prefix Information option's body, expected %d bytes: %w", numBodyBytes, ndpPrefixInformationLength, ErrNDPOptMalformedBody) } return NDPPrefixInformation(body), false, nil case NDPRecursiveDNSServerOptionType: - // RFC 8106 section 5.3.1 outlines that the RDNSS option - // must have a minimum length of 3 so it contains at - // least one IPv6 address. - if l < minNDPRecursiveDNSServerLength { - return nil, true, ErrNDPInvalidLength - } - opt := NDPRecursiveDNSServer(body) - if len(opt.Addresses()) == 0 { - return nil, true, ErrNDPOptMalformedBody + if err := opt.checkAddresses(); err != nil { + return nil, true, err } return opt, false, nil @@ -247,10 +246,16 @@ type NDPOptions []byte // // See NDPOptionIterator for more information. func (b NDPOptions) Iter(check bool) (NDPOptionIterator, error) { - it := NDPOptionIterator{opts: b} + it := NDPOptionIterator{ + opts: bytes.NewBuffer(b), + } if check { - for it2 := it; true; { + it2 := NDPOptionIterator{ + opts: bytes.NewBuffer(b), + } + + for { if _, done, err := it2.Next(); err != nil || done { return it, err } @@ -278,7 +283,7 @@ func (b NDPOptions) Serialize(s NDPOptionsSerializer) int { continue } - b[0] = o.Type() + b[0] = byte(o.Type()) // We know this safe because paddedLength would have returned // 0 if o had an invalid length (> 255 * lengthByteUnits). @@ -304,7 +309,7 @@ type NDPOption interface { fmt.Stringer // Type returns the type of the receiver. - Type() uint8 + Type() NDPOptionIdentifier // Length returns the length of the body of the receiver, in bytes. Length() int @@ -386,7 +391,7 @@ func (b NDPOptionsSerializer) Length() int { type NDPSourceLinkLayerAddressOption tcpip.LinkAddress // Type implements NDPOption.Type. -func (o NDPSourceLinkLayerAddressOption) Type() uint8 { +func (o NDPSourceLinkLayerAddressOption) Type() NDPOptionIdentifier { return NDPSourceLinkLayerAddressOptionType } @@ -426,7 +431,7 @@ func (o NDPSourceLinkLayerAddressOption) EthernetAddress() tcpip.LinkAddress { type NDPTargetLinkLayerAddressOption tcpip.LinkAddress // Type implements NDPOption.Type. -func (o NDPTargetLinkLayerAddressOption) Type() uint8 { +func (o NDPTargetLinkLayerAddressOption) Type() NDPOptionIdentifier { return NDPTargetLinkLayerAddressOptionType } @@ -466,7 +471,7 @@ func (o NDPTargetLinkLayerAddressOption) EthernetAddress() tcpip.LinkAddress { type NDPPrefixInformation []byte // Type implements NDPOption.Type. -func (o NDPPrefixInformation) Type() uint8 { +func (o NDPPrefixInformation) Type() NDPOptionIdentifier { return NDPPrefixInformationType } @@ -590,7 +595,7 @@ type NDPRecursiveDNSServer []byte // Type returns the type of an NDP Recursive DNS Server option. // // Type implements NDPOption.Type. -func (NDPRecursiveDNSServer) Type() uint8 { +func (NDPRecursiveDNSServer) Type() NDPOptionIdentifier { return NDPRecursiveDNSServerOptionType } @@ -613,7 +618,12 @@ func (o NDPRecursiveDNSServer) serializeInto(b []byte) int { // String implements fmt.Stringer.String. func (o NDPRecursiveDNSServer) String() string { - return fmt.Sprintf("%T(%s valid for %s)", o, o.Addresses(), o.Lifetime()) + lt := o.Lifetime() + addrs, err := o.Addresses() + if err != nil { + return fmt.Sprintf("%T([] valid for %s; err = %s)", o, lt, err) + } + return fmt.Sprintf("%T(%s valid for %s)", o, addrs, lt) } // Lifetime returns the length of time that the DNS server addresses @@ -632,29 +642,45 @@ func (o NDPRecursiveDNSServer) Lifetime() time.Duration { // Addresses returns the recursive DNS server IPv6 addresses that may be // used for name resolution. // -// Note, some of the addresses returned MAY be link-local addresses. +// Note, the addresses MAY be link-local addresses. +func (o NDPRecursiveDNSServer) Addresses() ([]tcpip.Address, error) { + var addrs []tcpip.Address + return addrs, o.iterAddresses(func(addr tcpip.Address) { addrs = append(addrs, addr) }) +} + +// checkAddresses iterates over the addresses in an NDP Recursive DNS Server +// option and returns any error it encounters. +func (o NDPRecursiveDNSServer) checkAddresses() error { + return o.iterAddresses(nil) +} + +// iterAddresses iterates over the addresses in an NDP Recursive DNS Server +// option and calls a function with each valid unicast IPv6 address. // -// Addresses may panic if o does not hold valid IPv6 addresses. -func (o NDPRecursiveDNSServer) Addresses() []tcpip.Address { - l := len(o) - if l < ndpRecursiveDNSServerAddressesOffset { - return nil +// Note, the addresses MAY be link-local addresses. +func (o NDPRecursiveDNSServer) iterAddresses(fn func(tcpip.Address)) error { + if l := len(o); l < minNDPRecursiveDNSServerBodySize { + return fmt.Errorf("got %d bytes for NDP Recursive DNS Server option's body, expected at least %d bytes: %w", l, minNDPRecursiveDNSServerBodySize, io.ErrUnexpectedEOF) } - l -= ndpRecursiveDNSServerAddressesOffset + o = o[ndpRecursiveDNSServerAddressesOffset:] + l := len(o) if l%IPv6AddressSize != 0 { - return nil + return fmt.Errorf("NDP Recursive DNS Server option's body ends in the middle of an IPv6 address (addresses body size = %d bytes): %w", l, ErrNDPOptMalformedBody) } - buf := o[ndpRecursiveDNSServerAddressesOffset:] - var addrs []tcpip.Address - for len(buf) > 0 { - addr := tcpip.Address(buf[:IPv6AddressSize]) + for i := 0; len(o) != 0; i++ { + addr := tcpip.Address(o[:IPv6AddressSize]) if !IsV6UnicastAddress(addr) { - return nil + return fmt.Errorf("%d-th address (%s) in NDP Recursive DNS Server option is not a valid unicast IPv6 address: %w", i, addr, ErrNDPOptMalformedBody) + } + + if fn != nil { + fn(addr) } - addrs = append(addrs, addr) - buf = buf[IPv6AddressSize:] + + o = o[IPv6AddressSize:] } - return addrs + + return nil } diff --git a/pkg/tcpip/header/ndpoptionidentifier_string.go b/pkg/tcpip/header/ndpoptionidentifier_string.go new file mode 100755 index 000000000..6fe9a336b --- /dev/null +++ b/pkg/tcpip/header/ndpoptionidentifier_string.go @@ -0,0 +1,50 @@ +// 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. + +// Code generated by "stringer -type NDPOptionIdentifier ."; DO NOT EDIT. + +package header + +import "strconv" + +func _() { + // An "invalid array index" compiler error signifies that the constant values have changed. + // Re-run the stringer command to generate them again. + var x [1]struct{} + _ = x[NDPSourceLinkLayerAddressOptionType-1] + _ = x[NDPTargetLinkLayerAddressOptionType-2] + _ = x[NDPPrefixInformationType-3] + _ = x[NDPRecursiveDNSServerOptionType-25] +} + +const ( + _NDPOptionIdentifier_name_0 = "NDPSourceLinkLayerAddressOptionTypeNDPTargetLinkLayerAddressOptionTypeNDPPrefixInformationType" + _NDPOptionIdentifier_name_1 = "NDPRecursiveDNSServerOptionType" +) + +var ( + _NDPOptionIdentifier_index_0 = [...]uint8{0, 35, 70, 94} +) + +func (i NDPOptionIdentifier) String() string { + switch { + case 1 <= i && i <= 3: + i -= 1 + return _NDPOptionIdentifier_name_0[_NDPOptionIdentifier_index_0[i]:_NDPOptionIdentifier_index_0[i+1]] + case i == 25: + return _NDPOptionIdentifier_name_1 + default: + return "NDPOptionIdentifier(" + strconv.FormatInt(int64(i), 10) + ")" + } +} diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go index 7f66c6c09..8140c6dd4 100755 --- a/pkg/tcpip/stack/ndp.go +++ b/pkg/tcpip/stack/ndp.go @@ -711,7 +711,8 @@ func (ndp *ndpState) handleRA(ip tcpip.Address, ra header.NDPRouterAdvert) { continue } - ndp.nic.stack.ndpDisp.OnRecursiveDNSServerOption(ndp.nic.ID(), opt.Addresses(), opt.Lifetime()) + addrs, _ := opt.Addresses() + ndp.nic.stack.ndpDisp.OnRecursiveDNSServerOption(ndp.nic.ID(), addrs, opt.Lifetime()) case header.NDPPrefixInformation: prefix := opt.Subnet() |