diff options
Diffstat (limited to 'pkg/tcpip')
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 10 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4_test.go | 120 |
2 files changed, 125 insertions, 5 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index 7e32b31b4..3d465e28a 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -374,8 +374,14 @@ func (b IPv4) Encode(i *IPv4Fields) { if hdrLen > len(b) { panic(fmt.Sprintf("encode received %d bytes, wanted >= %d", len(b), hdrLen)) } - if aLen != copy(b[options:], i.Options) { - _ = copy(b[options+len(i.Options):options+aLen], []byte{0, 0, 0, 0}) + opts := b[options:] + // This avoids bounds checks on the next line(s) which would happen even + // if there's no work to do. + if n := copy(opts, i.Options); n != aLen { + padding := opts[n:][:aLen-n] + for i := range padding { + padding[i] = 0 + } } } b.SetHeaderLength(uint8(hdrLen)) diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go index c6e565455..2abfccbf3 100644 --- a/pkg/tcpip/network/ipv4/ipv4_test.go +++ b/pkg/tcpip/network/ipv4/ipv4_test.go @@ -103,6 +103,105 @@ func TestExcludeBroadcast(t *testing.T) { }) } +// TestIPv4Encode checks that ipv4.Encode correctly fills out the requested +// fields when options are supplied. +func TestIPv4EncodeOptions(t *testing.T) { + tests := []struct { + name string + options header.IPv4Options + encodedOptions header.IPv4Options // reply should look like this + wantIHL int + }{ + { + name: "valid no options", + wantIHL: header.IPv4MinimumSize, + }, + { + name: "one byte options", + options: header.IPv4Options{1}, + encodedOptions: header.IPv4Options{1, 0, 0, 0}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "two byte options", + options: header.IPv4Options{1, 1}, + encodedOptions: header.IPv4Options{1, 1, 0, 0}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "three byte options", + options: header.IPv4Options{1, 1, 1}, + encodedOptions: header.IPv4Options{1, 1, 1, 0}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "four byte options", + options: header.IPv4Options{1, 1, 1, 1}, + encodedOptions: header.IPv4Options{1, 1, 1, 1}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "five byte options", + options: header.IPv4Options{1, 1, 1, 1, 1}, + encodedOptions: header.IPv4Options{1, 1, 1, 1, 1, 0, 0, 0}, + wantIHL: header.IPv4MinimumSize + 8, + }, + { + name: "thirty nine byte options", + options: header.IPv4Options{ + 1, 2, 3, 4, 5, 6, 7, 8, + 9, 10, 11, 12, 13, 14, 15, 16, + 17, 18, 19, 20, 21, 22, 23, 24, + 25, 26, 27, 28, 29, 30, 31, 32, + 33, 34, 35, 36, 37, 38, 39, + }, + encodedOptions: header.IPv4Options{ + 1, 2, 3, 4, 5, 6, 7, 8, + 9, 10, 11, 12, 13, 14, 15, 16, + 17, 18, 19, 20, 21, 22, 23, 24, + 25, 26, 27, 28, 29, 30, 31, 32, + 33, 34, 35, 36, 37, 38, 39, 0, + }, + wantIHL: header.IPv4MinimumSize + 40, + }, + } + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + paddedOptionLength := test.options.AllocationSize() + ipHeaderLength := header.IPv4MinimumSize + paddedOptionLength + if ipHeaderLength > header.IPv4MaximumHeaderSize { + t.Fatalf("IP header length too large: got = %d, want <= %d ", ipHeaderLength, header.IPv4MaximumHeaderSize) + } + totalLen := uint16(ipHeaderLength) + hdr := buffer.NewPrependable(int(totalLen)) + ip := header.IPv4(hdr.Prepend(ipHeaderLength)) + // To check the padding works, poison the last byte of the options space. + if paddedOptionLength != len(test.options) { + ip.SetHeaderLength(uint8(ipHeaderLength)) + ip.Options()[paddedOptionLength-1] = 0xff + ip.SetHeaderLength(0) + } + ip.Encode(&header.IPv4Fields{ + Options: test.options, + }) + options := ip.Options() + wantOptions := test.encodedOptions + if got, want := int(ip.HeaderLength()), test.wantIHL; got != want { + t.Errorf("got IHL of %d, want %d", got, want) + } + + // cmp.Diff does not consider nil slices equal to empty slices, but we do. + if len(wantOptions) == 0 && len(options) == 0 { + return + } + + if diff := cmp.Diff(wantOptions, options); diff != "" { + t.Errorf("options mismatch (-want +got):\n%s", diff) + } + }) + } +} + // TestIPv4Sanity sends IP/ICMP packets with various problems to the stack and // checks the response. func TestIPv4Sanity(t *testing.T) { @@ -197,6 +296,14 @@ func TestIPv4Sanity(t *testing.T) { replyOptions: header.IPv4Options{1, 1, 0, 0}, }, { + name: "Check option padding", + maxTotalLength: ipv4.MaxTotalSize, + transportProtocol: uint8(header.ICMPv4ProtocolNumber), + TTL: ttl, + options: header.IPv4Options{1, 1, 1}, + replyOptions: header.IPv4Options{1, 1, 1, 0}, + }, + { name: "bad header length", headerLength: header.IPv4MinimumSize - 1, maxTotalLength: ipv4.MaxTotalSize, @@ -599,9 +706,10 @@ func TestIPv4Sanity(t *testing.T) { }, }) - ipHeaderLength := header.IPv4MinimumSize + test.options.AllocationSize() + paddedOptionLength := test.options.AllocationSize() + ipHeaderLength := header.IPv4MinimumSize + paddedOptionLength if ipHeaderLength > header.IPv4MaximumHeaderSize { - t.Fatalf("too many bytes in options: got = %d, want <= %d ", ipHeaderLength, header.IPv4MaximumHeaderSize) + t.Fatalf("IP header length too large: got = %d, want <= %d ", ipHeaderLength, header.IPv4MaximumHeaderSize) } totalLen := uint16(ipHeaderLength + header.ICMPv4MinimumSize) hdr := buffer.NewPrependable(int(totalLen)) @@ -618,6 +726,12 @@ func TestIPv4Sanity(t *testing.T) { if test.maxTotalLength < totalLen { totalLen = test.maxTotalLength } + // To check the padding works, poison the options space. + if paddedOptionLength != len(test.options) { + ip.SetHeaderLength(uint8(ipHeaderLength)) + ip.Options()[paddedOptionLength-1] = 0x01 + } + ip.Encode(&header.IPv4Fields{ TotalLength: totalLen, Protocol: test.transportProtocol, @@ -732,7 +846,7 @@ func TestIPv4Sanity(t *testing.T) { } // If the IP options change size then the packet will change size, so // some IP header fields will need to be adjusted for the checks. - sizeChange := len(test.replyOptions) - len(test.options) + sizeChange := len(test.replyOptions) - paddedOptionLength checker.IPv4(t, replyIPHeader, checker.IPv4HeaderLength(ipHeaderLength+sizeChange), |