func (loader *PELoader) resolveThunkTable(
ws *workspace.Workspace,
mod *workspace.LoadedModule,
moduleName string,
rvaTable AS.RVA) error {
var offset AS.RVA = rvaTable
for {
rvaImport, e := mod.MemReadRva(ws, offset)
check(e)
if rvaImport == 0x0 {
break
}
if Flags64(rvaImport).isSet(FLAG_IMPORT_BY_ORDINAL) {
logrus.Infof(" import by ordinal: %03x", uint64(rvaImport)&uint64(0x7FFFFFFF))
// TODO: replace thunk with handler
// notes:
// 32: PUSH 0xAABBCCDD --> 68 DD CC BB AA
// JMP 0xAABBCCDD --> E9 D9 CC BB AA ugh, relative jump. do a push/ret instead.
// RET --> C3
//
mod.Imports[offset] = workspace.LinkedSymbol{
ModuleName: moduleName,
SymbolName: fmt.Sprintf("ordinal-%x", uint64(rvaImport)&uint64(0x7FFFFFFF)),
}
} else {
d, e := mod.MemRead(ws, rvaImport, 0x100)
check(e)
p := bytes.NewBuffer(d)
var importByName ImageImportByName
binary.Read(p, binary.LittleEndian, &importByName.Hint)
importByName.Name, e = readAscii(d[2:])
check(e)
logrus.Infof(" import by name: %s@%s", importByName.Name, rvaImport)
// TODO: replace thunk with handler
mod.Imports[offset] = workspace.LinkedSymbol{
ModuleName: moduleName,
SymbolName: importByName.Name,
}
}
offset += 4
}
return nil
}
func (loader *PELoader) resolveExports(
ws *workspace.Workspace,
mod *workspace.LoadedModule,
dataDirectory [16]pe.DataDirectory) error {
exportDirectory := dataDirectory[0]
exportRva := AS.RVA(exportDirectory.VirtualAddress)
exportSize := exportDirectory.Size
logrus.Infof("export rva: %s", exportRva)
logrus.Infof("export size: 0x%x", exportSize)
d, e := mod.MemRead(ws, AS.RVA(exportDirectory.VirtualAddress), uint64(exportDirectory.Size))
check(e)
p := bytes.NewBuffer(d)
var dir ImageExportDirectory
binary.Read(p, binary.LittleEndian, &dir.Characteristics)
binary.Read(p, binary.LittleEndian, &dir.TimeDateStamp)
binary.Read(p, binary.LittleEndian, &dir.MajorVersion)
binary.Read(p, binary.LittleEndian, &dir.MinorVersion)
binary.Read(p, binary.LittleEndian, &dir.rvaName)
binary.Read(p, binary.LittleEndian, &dir.Base)
binary.Read(p, binary.LittleEndian, &dir.NumberOfFunctions)
binary.Read(p, binary.LittleEndian, &dir.NumberOfNames)
binary.Read(p, binary.LittleEndian, &dir.rvaAddressOfFunctions)
binary.Read(p, binary.LittleEndian, &dir.rvaAddressOfNames)
binary.Read(p, binary.LittleEndian, &dir.rvaAddressOfNameOrdinals)
if dir.rvaAddressOfFunctions == 0 {
panic("address of functions is NULL")
}
exportModuleNameBuf, e := mod.MemRead(ws, AS.RVA(dir.rvaName), 0x100)
check(e)
exportModuleName, e := readAscii(exportModuleNameBuf)
logrus.Infof("export name: %s", string(exportModuleName))
check(e)
logrus.Infof("time date stamp: 0x%x", dir.TimeDateStamp)
// note closure over dir, mod, ws
readFunctionRva := func(i uint32) (AS.RVA, error) {
if i > dir.NumberOfFunctions {
panic("function index too large")
}
// sizeof(RVA) is always 4 bytes, even on x64
return mod.MemReadRva(ws, AS.RVA(dir.rvaAddressOfFunctions+4*i))
}
// isForwardedExport returns true when the provided RVA falls within the
// export directory table, which is used to signify that an export is
// fowarded to another module.
// implementation: note closure over loader
isForwardedExport := func(rvaFn AS.RVA) bool {
if uint32(rvaFn) < exportDirectory.VirtualAddress {
return false
}
if uint32(rvaFn) >= exportDirectory.VirtualAddress+exportDirectory.Size {
return false
}
return true
}
// implementation: node closure over mod, ws
readForwardedSymbol := func(rvaFn AS.RVA) (workspace.LinkedSymbol, error) {
var forwardedSymbol workspace.LinkedSymbol
forwardedNameBuf, e := mod.MemRead(ws, AS.RVA(rvaFn), 0x100)
check(e)
forwardedName, e := readAscii(forwardedNameBuf)
check(e)
i := strings.LastIndex(forwardedName, ".")
if i == -1 {
panic("expected to find a '.' in the module name")
}
if i >= len(forwardedName) {
panic("module name ends in period")
}
forwardedSymbol.ModuleName = forwardedName[:i]
forwardedSymbol.SymbolName = forwardedName[i+1:]
return forwardedSymbol, nil
}
// resolve exports by ordinals first
for i := uint32(0); i < dir.NumberOfFunctions; i++ {
ordinal := uint16(i + dir.Base)
rvaFn, e := readFunctionRva(i)
check(e)
isForwarded := isForwardedExport(rvaFn)
sym := workspace.ExportedSymbol{
RVA: rvaFn,
IsForwarded: isForwarded,
}
if isForwarded {
fsym, e := readForwardedSymbol(rvaFn)
check(e)
sym.ForwardedSymbol = fsym
}
mod.ExportsByOrdinal[ordinal] = sym
if isForwarded {
logrus.Infof(" export: (ordinal) %x: %s -> %s.%s",
ordinal, rvaFn, sym.ForwardedSymbol.ModuleName, sym.ForwardedSymbol.SymbolName)
} else {
logrus.Infof(" export: (ordinal) %x: %s", ordinal, rvaFn)
}
}
// resolve exports by name
for i := uint32(0); i < dir.NumberOfNames; i++ {
// sizeof(RVA) is always 4 bytes, even on x64
rvaName, e := mod.MemReadRva(ws, AS.RVA(dir.rvaAddressOfNames+4*i))
check(e)
// sizeof(ordinal) is always 2 bytes
nameOrdinal, e := mod.MemReadShort(ws, AS.RVA(dir.rvaAddressOfNameOrdinals+2*i))
check(e)
rvaFn, e := readFunctionRva(uint32(nameOrdinal))
check(e)
nameBuf, e := mod.MemRead(ws, AS.RVA(rvaName), 0x100)
check(e)
name, e := readAscii(nameBuf)
check(e)
isForwarded := isForwardedExport(rvaFn)
sym := workspace.ExportedSymbol{
RVA: rvaFn,
IsForwarded: isForwarded,
}
if isForwarded {
fsym, e := readForwardedSymbol(rvaFn)
check(e)
sym.ForwardedSymbol = fsym
}
mod.ExportsByName[name] = sym
if isForwarded {
logrus.Infof(" export: %s: %s -> %s.%s",
name, rvaFn, sym.ForwardedSymbol.ModuleName, sym.ForwardedSymbol.SymbolName)
} else {
logrus.Infof(" export: %s: %s", name, rvaFn)
}
}
return nil
}