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Add go:notinheap annotations to all the WFP API types.
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This should prevent us from accidentally passing Go memory to Windows.

Also fix up a couple cases where we were, in fact, passing Go memory
to Windows.

Signed-off-by: David Anderson <danderson@tailscale.com>
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@danderson
danderson committed Mar 14, 2021
1 parent 3c2c0fd commit 96105dd
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Showing 6 changed files with 68 additions and 36 deletions.
21 changes: 21 additions & 0 deletions compose.go
View file
Expand Up @@ -8,6 +8,27 @@ import (
"golang.org/x/sys/windows"
)

func toSession0(a *arena, opts *SessionOptions) *fwpmSession0 {
ret := (*fwpmSession0)(a.alloc(unsafe.Sizeof(fwpmSession0{})))
*ret = fwpmSession0{
DisplayData: fwpmDisplayData0{
Name: toUint16(a, opts.Name),
Description: toUint16(a, opts.Description),
},
TxnWaitTimeoutMillis: uint32(opts.TransactionStartTimeout.Milliseconds()),
}
if opts.Dynamic {
ret.Flags = fwpmSession0FlagDynamic
}
return ret
}

func toSublayerEnumTemplate0(a *arena, provider *windows.GUID) *fwpmSublayerEnumTemplate0 {
ret := (*fwpmSublayerEnumTemplate0)(a.alloc(unsafe.Sizeof(fwpmSublayerEnumTemplate0{})))
ret.ProviderKey = toGUID(a, provider)
return ret
}

func toSublayer0(a *arena, sl *Sublayer) *fwpmSublayer0 {
ret := (*fwpmSublayer0)(a.alloc(unsafe.Sizeof(fwpmSublayer0{})))
*ret = fwpmSublayer0{
Expand Down
26 changes: 10 additions & 16 deletions firewall.go
View file
Expand Up @@ -56,20 +56,13 @@ func New(opts *SessionOptions) (*Session, error) {
opts = &SessionOptions{}
}

session := fwpmSession0{
DisplayData: fwpmDisplayData0{
Name: windows.StringToUTF16Ptr(opts.Name),
Description: windows.StringToUTF16Ptr(opts.Description),
},
TxnWaitTimeoutMillis: uint32(opts.TransactionStartTimeout.Milliseconds()),
}
if opts.Dynamic {
session.Flags = fwpmSession0FlagDynamic
}
var a arena
defer a.dispose()

var handle windows.Handle
s0 := toSession0(&a, opts)

err := fwpmEngineOpen0(nil, authnServiceWinNT, nil, &session, &handle)
var handle windows.Handle
err := fwpmEngineOpen0(nil, authnServiceWinNT, nil, s0, &handle)
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -232,12 +225,13 @@ type Sublayer struct {
// Sublayers returns available Sublayers. If provider is non-nil, only
// Sublayers registered to that Provider are returned.
func (s *Session) Sublayers(provider *windows.GUID) ([]*Sublayer, error) {
tpl := fwpmSublayerEnumTemplate0{
ProviderKey: provider,
}
var a arena
defer a.dispose()

tpl := toSublayerEnumTemplate0(&a, provider)

var enum windows.Handle
if err := fwpmSubLayerCreateEnumHandle0(s.handle, &tpl, &enum); err != nil {
if err := fwpmSubLayerCreateEnumHandle0(s.handle, tpl, &enum); err != nil {
return nil, err
}
defer fwpmSubLayerDestroyEnumHandle0(s.handle, enum)
Expand Down
30 changes: 16 additions & 14 deletions parse.go
View file
Expand Up @@ -91,8 +91,9 @@ func fromLayer0(array **fwpmLayer0, num uint32) ([]*Layer, error) {
sh.Len = int(layer.NumFields)
sh.Data = uintptr(unsafe.Pointer(layer.Fields))

for _, field := range fields {
typ, err := fieldType(&field)
for i := range fields {
field := &fields[i]
typ, err := fieldType(field)
if err != nil {
return nil, fmt.Errorf("finding type of field %s: %w", GUIDName(*field.FieldKey), err)
}
Expand Down Expand Up @@ -124,7 +125,7 @@ func fromSublayer0(array **fwpmSublayer0, num uint32) []*Sublayer {
Name: windows.UTF16PtrToString(sublayer.DisplayData.Name),
Description: windows.UTF16PtrToString(sublayer.DisplayData.Description),
Persistent: (sublayer.Flags & fwpmSublayerFlagsPersistent) != 0,
ProviderData: fromByteBlob(sublayer.ProviderData),
ProviderData: fromByteBlob(&sublayer.ProviderData),
Weight: sublayer.Weight,
}
if sublayer.ProviderKey != nil {
Expand Down Expand Up @@ -157,7 +158,7 @@ func fromProvider0(array **fwpmProvider0, num uint32) []*Provider {
Description: windows.UTF16PtrToString(provider.DisplayData.Description),
Persistent: (provider.Flags & fwpmProviderFlagsPersistent) != 0,
Disabled: (provider.Flags & fwpmProviderFlagsDisabled) != 0,
Data: fromByteBlob(provider.ProviderData),
Data: fromByteBlob(&provider.ProviderData),
ServiceName: windows.UTF16PtrToString(provider.ServiceName),
}
ret = append(ret, p)
Expand Down Expand Up @@ -186,7 +187,7 @@ func fromFilter0(array **fwpmFilter0, num uint32, layerTypes layerTypes) ([]*Rul
Persistent: (rule.Flags & fwpmFilterFlagsPersistent) != 0,
BootTime: (rule.Flags & fwpmFilterFlagsBootTime) != 0,
Provider: rule.ProviderKey,
ProviderData: fromByteBlob(rule.ProviderData),
ProviderData: fromByteBlob(&rule.ProviderData),
Disabled: (rule.Flags & fwpmFilterFlagsDisabled) != 0,
}
if rule.EffectiveWeight.Type == dataTypeUint64 {
Expand Down Expand Up @@ -226,13 +227,14 @@ func fromCondition0(condArray *fwpmFilterCondition0, num uint32, fieldTypes fiel

var ret []*Match

for _, cond := range conditions {
for i := range conditions {
cond := &conditions[i]
fieldType, ok := fieldTypes[cond.FieldKey]
if !ok {
return nil, fmt.Errorf("unknown field %s", cond.FieldKey)
}

v, err := fromValue0(fwpValue0(cond.Value), fieldType)
v, err := fromValue0((*fwpValue0)(unsafe.Pointer(&cond.Value)), fieldType)
if err != nil {
return nil, fmt.Errorf("getting value for match [%s %s]: %w", GUIDName(cond.FieldKey), cond.MatchType, err)
}
Expand All @@ -249,7 +251,7 @@ func fromCondition0(condArray *fwpmFilterCondition0, num uint32, fieldTypes fiel
}

// fromValue converts a fwpValue0 to the corresponding Go value.
func fromValue0(v fwpValue0, ftype reflect.Type) (interface{}, error) {
func fromValue0(v *fwpValue0, ftype reflect.Type) (interface{}, error) {
// For most types, the field type and raw data type match up. But
// for some, the raw type can vary from the field type
// (e.g. comparing an IP to a prefix). Get the complex matchups
Expand Down Expand Up @@ -316,7 +318,7 @@ func fromValue0(v fwpValue0, ftype reflect.Type) (interface{}, error) {
copy(ret[:], fromBytes(v.Value, 16))
return ret, nil
case dataTypeByteBlob:
return fromByteBlob(**(**fwpByteBlob)(unsafe.Pointer(&v.Value))), nil
return fromByteBlob(*(**fwpByteBlob)(unsafe.Pointer(&v.Value))), nil
case dataTypeSID:
return parseSID(&v.Value)
// case dataTypeSecurityDescriptor:
Expand Down Expand Up @@ -373,18 +375,18 @@ func parseSID(v *uintptr) (*windows.SID, error) {
func parseSecurityDescriptor(v *uintptr) (*windows.SECURITY_DESCRIPTOR, error) {
// The security descriptor is embedded in the API response as
// a byte slice.
bb := fromByteBlob(**(**fwpByteBlob)(unsafe.Pointer(v)))
bb := fromByteBlob(*(**fwpByteBlob)(unsafe.Pointer(v)))
relSD := (*windows.SECURITY_DESCRIPTOR)(unsafe.Pointer(&bb[0]))
return relSD, nil
}

func parseRange0(v *uintptr, ftype reflect.Type) (interface{}, error) {
r := *(**fwpRange0)(unsafe.Pointer(v))
from, err := fromValue0(r.From, ftype)
from, err := fromValue0(&r.From, ftype)
if err != nil {
return nil, err
}
to, err := fromValue0(r.To, ftype)
to, err := fromValue0(&r.To, ftype)
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -421,8 +423,8 @@ func fromBytes(bb uintptr, length int) []byte {

// fromByteBlob extracts the bytes from bb and returns them as a
// []byte that doesn't alias C memory.
func fromByteBlob(bb fwpByteBlob) []byte {
if bb.Size == 0 {
func fromByteBlob(bb *fwpByteBlob) []byte {
if bb == nil || bb.Size == 0 {
return nil
}

Expand Down
2 changes: 1 addition & 1 deletion syscall.go
View file
Expand Up @@ -22,7 +22,7 @@ package wf

//sys fwpmSubLayerDeleteByKey0(engineHandle windows.Handle, guid *windows.GUID) (err error) [failretval!=0] = fwpuclnt.FwpmSubLayerDeleteByKey0

//sys fwpmProviderCreateEnumHandle0(engineHandle windows.Handle, enumTemplate *fwpmProviderEnumTemplate0, handle *windows.Handle) (err error) [failretval!=0] = fwpuclnt.FwpmProviderCreateEnumHandle0
//sys fwpmProviderCreateEnumHandle0(engineHandle windows.Handle, enumTemplate *struct{}, handle *windows.Handle) (err error) [failretval!=0] = fwpuclnt.FwpmProviderCreateEnumHandle0

//sys fwpmProviderDestroyEnumHandle0(engineHandle windows.Handle, enumHandle windows.Handle) (err error) [failretval!=0] = fwpuclnt.FwpmProviderDestroyEnumHandle0

Expand Down
23 changes: 19 additions & 4 deletions types.go
View file
Expand Up @@ -4,6 +4,7 @@ import (
"golang.org/x/sys/windows"
)

//go:notinheap
type fwpmDisplayData0 struct {
Name *uint16
Description *uint16
Expand All @@ -13,6 +14,7 @@ type fwpmSession0Flags uint32

const fwpmSession0FlagDynamic = 1

//go:notinheap
type fwpmSession0 struct {
SessionKey windows.GUID
DisplayData fwpmDisplayData0
Expand All @@ -31,6 +33,7 @@ const (
authnServiceDefault authnService = 0xffffffff
)

//go:notinheap
type fwpmLayerEnumTemplate0 struct {
reserved uint64
}
Expand All @@ -44,6 +47,7 @@ const (
fwpmLayerFlagsBuffered
)

//go:notinheap
type fwpmLayer0 struct {
LayerKey windows.GUID
DisplayData fwpmDisplayData0
Expand Down Expand Up @@ -93,16 +97,19 @@ const (
// dataTypeUnicodeString dataType = 17
// dataTypeBitmapArray64 dataType = 20

//go:notinheap
type fwpmField0 struct {
FieldKey *windows.GUID
Type fwpmFieldType
DataType dataType
}

//go:notinheap
type fwpmSublayerEnumTemplate0 struct {
ProviderKey *windows.GUID
}

//go:notinheap
type fwpByteBlob struct {
Size uint32
Data *uint8
Expand All @@ -112,6 +119,7 @@ type fwpmSublayerFlags uint32

const fwpmSublayerFlagsPersistent fwpmSublayerFlags = 1

//go:notinheap
type fwpmSublayer0 struct {
SublayerKey windows.GUID
DisplayData fwpmDisplayData0
Expand All @@ -121,17 +129,14 @@ type fwpmSublayer0 struct {
Weight uint16
}

type fwpmProviderEnumTemplate0 struct {
Reserved uint64
}

type fwpmProviderFlags uint32

const (
fwpmProviderFlagsPersistent fwpmProviderFlags = 0x01
fwpmProviderFlagsDisabled fwpmProviderFlags = 0x10
)

//go:notinheap
type fwpmProvider0 struct {
ProviderKey windows.GUID
DisplayData fwpmDisplayData0
Expand All @@ -140,6 +145,7 @@ type fwpmProvider0 struct {
ServiceName *uint16
}

//go:notinheap
type fwpValue0 struct {
Type dataType
Value uintptr // unioned value
Expand All @@ -157,11 +163,13 @@ const (
fwpmFilterFlagsIndexed
)

//go:notinheap
type fwpmAction0 struct {
Type Action
GUID windows.GUID
}

//go:notinheap
type fwpmFilter0 struct {
FilterKey windows.GUID
DisplayData fwpmDisplayData0
Expand All @@ -180,31 +188,37 @@ type fwpmFilter0 struct {
EffectiveWeight fwpValue0
}

//go:notinheap
type fwpConditionValue0 struct {
Type dataType
Value uintptr
}

//go:notinheap
type fwpmFilterCondition0 struct {
FieldKey windows.GUID
MatchType MatchType
Value fwpConditionValue0
}

//go:notinheap
type fwpV4AddrAndMask struct {
Addr, Mask uint32
}

//go:notinheap
type fwpV6AddrAndMask struct {
Addr [16]byte
PrefixLength uint8
}

//go:notinheap
type fwpmProviderContextEnumTemplate0 struct {
ProviderKey *windows.GUID
ProviderContextType uint32
}

//go:notinheap
type fwpmFilterEnumTemplate0 struct {
ProviderKey *windows.GUID
LayerKey windows.GUID
Expand All @@ -217,6 +231,7 @@ type fwpmFilterEnumTemplate0 struct {
CalloutKey *windows.GUID
}

//go:notinheap
type fwpRange0 struct {
From, To fwpValue0
}
Expand Down
2 changes: 1 addition & 1 deletion zsyscall_windows.go
View file

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