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codeql/cpp/ql/lib/semmle/code/cpp/models/implementations/StdString.qll
Mathias Vorreiter Pedersen 3f5b4a81cf C++: Fix more inconsistencies.
2024-07-24 17:53:28 +01:00

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/**
* Provides implementation classes modeling `std::string` (and other
* instantiations of `std::basic_string`) and `std::ostream`. See
* `semmle.code.cpp.models.Models` for usage information.
*/
import semmle.code.cpp.models.interfaces.Taint
import semmle.code.cpp.models.interfaces.Iterator
import semmle.code.cpp.models.interfaces.DataFlow
import semmle.code.cpp.models.interfaces.SideEffect
import semmle.code.cpp.models.interfaces.Alias
/**
* The `std::basic_string` template class instantiations.
*/
private class StdBasicString extends ClassTemplateInstantiation {
StdBasicString() { this.hasQualifiedName(["std", "bsl"], "basic_string") }
}
/**
* The `std::basic_string::iterator` declaration.
*
* Intuitively, this class shouldn't be necessary as it's already captured
* by the `StdIterator` class. However, this class ensures that the typedef inside the
* body of the `std::string` class is also seen as an iterator.
*
* Eventually, we should be consistent about which of the following should be recognized as iterators:
* 1. The typedef type.
* 2. The template class of the resolved type.
* 3. Any instantiation of the resolved type.
*/
private class StdBasicStringIterator extends Iterator, Type {
StdBasicStringIterator() {
this.getEnclosingElement() instanceof StdBasicString and this.hasName("iterator")
}
}
/**
* A `std::string` function for which taint should be propagated.
*/
abstract private class StdStringTaintFunction extends TaintFunction {
/**
* Gets the index of a parameter to this function that is a string.
*/
final int getAStringParameterIndex() {
exists(Type paramType | paramType = this.getParameter(result).getUnspecifiedType() |
// e.g. `std::basic_string::CharT *`
paramType instanceof PointerType
or
// e.g. `std::basic_string &`, avoiding `const Allocator&`
paramType instanceof ReferenceType and
not paramType.(ReferenceType).getBaseType() =
this.getDeclaringType().getTemplateArgument(2).(Type).getUnspecifiedType()
)
}
/**
* Gets the index of a parameter to this function that is a character.
*/
final int getACharParameterIndex() {
exists(Type paramType | paramType = this.getParameter(result).getUnspecifiedType() |
// i.e. `std::basic_string::CharT`
paramType = this.getDeclaringType().getTemplateArgument(0).(Type).getUnspecifiedType()
)
}
/**
* Gets the index of a parameter to this function that is an iterator.
*/
final int getAnIteratorParameterIndex() {
this.getParameter(result).getUnspecifiedType() instanceof Iterator
}
}
/**
* Additional model for `std::string` constructors that reference the character
* type of the container, or an iterator. For example construction from
* iterators:
* ```
* std::string b(a.begin(), a.end());
* ```
*/
private class StdStringConstructor extends Constructor, StdStringTaintFunction, SideEffectFunction,
AliasFunction
{
StdStringConstructor() { this.getDeclaringType() instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// taint flow from any parameter of the value type to the returned object
(
input.isParameterDeref(this.getAStringParameterIndex()) or
input.isParameter(this.getACharParameterIndex()) or
input.isParameter(this.getAnIteratorParameterIndex())
) and
(
output.isReturnValue() // TODO: this is only needed for AST data flow, which treats constructors as returning the new object
or
output.isQualifierObject()
)
}
override predicate parameterNeverEscapes(int index) { index = -1 }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
i = -1 and buffer = false and mustWrite = true
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
i = -1 and buffer = false
}
}
private class StdStringDestructor extends Destructor, SideEffectFunction, AliasFunction {
StdStringDestructor() { this.getDeclaringType() instanceof StdBasicString }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate parameterNeverEscapes(int index) { index = -1 }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
i = -1 and buffer = false and mustWrite = true
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
i = -1 and buffer = false
}
}
/**
* The `std::string` function `c_str`.
*/
class StdStringCStr extends MemberFunction {
StdStringCStr() { this.getClassAndName("c_str") instanceof StdBasicString }
}
private class StdStringCStrModel extends StdStringCStr, StdStringTaintFunction {
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from string itself (qualifier) to return value
input.isQualifierObject() and
output.isReturnValueDeref()
}
}
/**
* The `std::string` function `data`.
*/
class StdStringData extends MemberFunction {
StdStringData() { this.getClassAndName("data") instanceof StdBasicString }
}
private class StdStringDataModel extends StdStringData, StdStringTaintFunction {
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from string itself (qualifier) to return value
input.isQualifierObject() and
output.isReturnValueDeref()
or
// reverse flow from returned reference to the qualifier (for writes to
// `data`)
input.isReturnValueDeref() and
output.isQualifierObject()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
}
/**
* The `std::string` function `push_back`.
*/
private class StdStringPush extends StdStringTaintFunction {
StdStringPush() { this.getClassAndName("push_back") instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from parameter to qualifier
input.isParameter(0) and
output.isQualifierObject()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
}
/**
* The `std::string` functions `front` and `back`.
*/
private class StdStringFrontBack extends StdStringTaintFunction {
StdStringFrontBack() { this.getClassAndName(["front", "back"]) instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from object to returned reference
input.isQualifierObject() and
output.isReturnValueDeref()
}
}
/**
* The (non-member) `std::string` function `operator+`.
*/
private class StdStringPlus extends StdStringTaintFunction, SideEffectFunction, AliasFunction {
StdStringPlus() {
this.hasQualifiedName(["std", "bsl"], "operator+") and
this.getUnspecifiedType() instanceof StdBasicString
}
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from parameters to return value
(
input.isParameterDeref(0) or
input.isParameterDeref(1)
) and
output.isReturnValue()
}
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
this.getParameter(i).getUnspecifiedType() instanceof ReferenceType and
buffer = false
or
this.getParameter(i).getUnspecifiedType() instanceof PointerType and
buffer = true
}
override predicate parameterNeverEscapes(int index) { index = [0, 1] }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
}
/**
* The `std::string` functions `operator+=`, `append` and `replace`.
* All of these functions combine the existing string with a new
* string (or character) from one of the arguments.
*/
private class StdStringAppend extends StdStringTaintFunction, SideEffectFunction, AliasFunction {
StdStringAppend() {
this.getClassAndName(["operator+=", "append", "replace"]) instanceof StdBasicString
}
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from string and parameter to string (qualifier) and return value
(
input.isQualifierObject() or
input.isParameterDeref(this.getAStringParameterIndex()) or
input.isParameter(this.getACharParameterIndex()) or
input.isParameter(this.getAnIteratorParameterIndex())
) and
(
output.isQualifierObject() or
output.isReturnValueDeref()
)
or
// reverse flow from returned reference to the qualifier (for writes to
// the result)
input.isReturnValueDeref() and
output.isQualifierObject()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
i = -1 and mustWrite = false and buffer = true
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
i = [-1, 0] and buffer = true
}
override predicate parameterNeverEscapes(int index) { index = [-1, 0] }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
}
/**
* The `std::string` function `insert`.
*/
private class StdStringInsert extends StdStringTaintFunction {
StdStringInsert() { this.getClassAndName("insert") instanceof StdBasicString }
/**
* Holds if the return type is an iterator.
*/
predicate hasIteratorReturnValue() { this.getType() instanceof Iterator }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from string and parameter to string (qualifier) and return value
(
input.isQualifierObject() or
input.isParameterDeref(this.getAStringParameterIndex()) or
input.isParameter(this.getACharParameterIndex()) or
input.isParameter(this.getAnIteratorParameterIndex())
) and
(
output.isQualifierObject()
or
if this.hasIteratorReturnValue() then output.isReturnValue() else output.isReturnValueDeref()
)
or
// reverse flow from returned reference to the qualifier (for writes to
// the result)
not this.hasIteratorReturnValue() and
input.isReturnValueDeref() and
output.isQualifierObject()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
}
/**
* The standard function `std::string.assign`.
*/
private class StdStringAssign extends StdStringTaintFunction {
StdStringAssign() { this.getClassAndName("assign") instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from parameter to string itself (qualifier) and return value
(
input.isParameterDeref(this.getAStringParameterIndex()) or
input.isParameter(this.getACharParameterIndex()) or
input.isParameter(this.getAnIteratorParameterIndex())
) and
(
output.isQualifierObject() or
output.isReturnValueDeref()
)
or
// reverse flow from returned reference to the qualifier (for writes to
// the result)
input.isReturnValueDeref() and
output.isQualifierObject()
}
}
/**
* The standard function `std::string.copy`.
*/
private class StdStringCopy extends StdStringTaintFunction {
StdStringCopy() { this.getClassAndName("copy") instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// copy(dest, num, pos)
input.isQualifierObject() and
output.isParameterDeref(0)
}
}
/**
* The standard function `std::string.substr`.
*/
private class StdStringSubstr extends StdStringTaintFunction {
StdStringSubstr() { this.getClassAndName("substr") instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// substr(pos, num)
input.isQualifierObject() and
output.isReturnValue()
}
}
/**
* The `std::string` functions `at` and `operator[]`.
*/
private class StdStringAt extends StdStringTaintFunction, SideEffectFunction, AliasFunction {
StdStringAt() { this.getClassAndName(["at", "operator[]"]) instanceof StdBasicString }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to referenced return value
input.isQualifierObject() and
output.isReturnValueDeref()
or
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate parameterNeverEscapes(int index) { index = -1 }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
none()
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
i = -1 and buffer = false
}
}
/**
* The `std::basic_istream` template class instantiations.
*/
private class StdBasicIStream extends ClassTemplateInstantiation {
StdBasicIStream() { this.hasQualifiedName(["std", "bsl"], "basic_istream") }
}
private class StdBasicIfStream extends ClassTemplateInstantiation {
StdBasicIfStream() { this.hasQualifiedName(["std", "bsl"], "basic_ifstream") }
}
class StdBasicIfStreamConstructor extends Constructor, SideEffectFunction, AliasFunction {
StdBasicIfStreamConstructor() { this.getDeclaringType() instanceof StdBasicIfStream }
override predicate parameterNeverEscapes(int index) { index = -1 }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
i = -1 and buffer = false and mustWrite = true
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
exists(Type t | t = this.getParameter(i).getUnspecifiedType() |
t instanceof PointerType and buffer = true
or
t instanceof ReferenceType and buffer = false
)
}
}
class StdBasicIfStreamDestructor extends Destructor, SideEffectFunction, AliasFunction {
StdBasicIfStreamDestructor() { this.getDeclaringType() instanceof StdBasicIfStream }
override predicate parameterNeverEscapes(int index) { index = -1 }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
i = -1 and buffer = false and mustWrite = true
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
i = -1 and buffer = false
}
}
/**
* The `std::istream` function `operator>>` (defined as a member function).
*/
private class StdIStreamIn extends DataFlowFunction, TaintFunction {
StdIStreamIn() { this.getClassAndName("operator>>") instanceof StdBasicIStream }
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// returns reference to `*this`
input.isQualifierAddress() and
output.isReturnValue()
or
input.isQualifierObject() and
output.isReturnValueDeref()
}
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to first parameter
input.isQualifierObject() and
output.isParameterDeref(0)
or
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
}
/**
* The `std::istream` function `operator>>` (defined as a non-member function).
*/
private class StdIStreamInNonMember extends DataFlowFunction, TaintFunction {
StdIStreamInNonMember() {
this.hasQualifiedName(["std", "bsl"], "operator>>") and
this.getUnspecifiedType().(ReferenceType).getBaseType() instanceof StdBasicIStream
}
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter to return value
input.isParameter(0) and
output.isReturnValue()
or
input.isParameterDeref(0) and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter to second parameter
input.isParameterDeref(0) and
output.isParameterDeref(1)
or
// reverse flow from returned reference to the first parameter
input.isReturnValueDeref() and
output.isParameterDeref(0)
}
}
/**
* The `std::istream` functions `get` (without parameters) and `peek`.
*/
private class StdIStreamGet extends TaintFunction {
StdIStreamGet() {
this.getClassAndName(["get", "peek"]) instanceof StdBasicIStream and
this.getNumberOfParameters() = 0
}
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to return value
input.isQualifierObject() and
output.isReturnValue()
}
}
/**
* The `std::istream` functions `get` (with parameters) and `read`.
*/
private class StdIStreamRead extends DataFlowFunction, TaintFunction {
StdIStreamRead() {
this.getClassAndName(["get", "read"]) instanceof StdBasicIStream and
this.getNumberOfParameters() > 0
}
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// returns reference to `*this`
input.isQualifierAddress() and
output.isReturnValue()
or
input.isQualifierObject() and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to first parameter
input.isQualifierObject() and
output.isParameterDeref(0)
or
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
}
/**
* The `std::istream` function `readsome`.
*/
private class StdIStreamReadSome extends TaintFunction {
StdIStreamReadSome() { this.getClassAndName("readsome") instanceof StdBasicIStream }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to first parameter
input.isQualifierObject() and
output.isParameterDeref(0)
}
}
/**
* The `std::istream` function `putback`.
*/
private class StdIStreamPutBack extends DataFlowFunction, TaintFunction {
StdIStreamPutBack() { this.getClassAndName("putback") instanceof StdBasicIStream }
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// returns reference to `*this`
input.isQualifierAddress() and
output.isReturnValue()
or
input.isQualifierObject() and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter (value or pointer) to qualifier
input.isParameter(0) and
output.isQualifierObject()
or
input.isParameterDeref(0) and
output.isQualifierObject()
or
// flow from first parameter (value or pointer) to return value
input.isParameter(0) and
output.isReturnValueDeref()
or
input.isParameterDeref(0) and
output.isReturnValueDeref()
or
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
}
/**
* The `std::istream` function `getline`.
*/
private class StdIStreamGetLine extends DataFlowFunction, TaintFunction {
StdIStreamGetLine() { this.getClassAndName("getline") instanceof StdBasicIStream }
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// returns reference to `*this`
input.isQualifierAddress() and
output.isReturnValue()
or
input.isQualifierObject() and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to first parameter
input.isQualifierObject() and
output.isParameterDeref(0)
or
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
}
/**
* The (non-member) function `std::getline`.
*/
private class StdGetLine extends DataFlowFunction, TaintFunction {
StdGetLine() { this.hasQualifiedName(["std", "bsl"], "getline") }
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter to return value
input.isParameter(0) and
output.isReturnValue()
or
input.isParameterDeref(0) and
output.isReturnValueDeref()
}
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter to second parameter
input.isParameterDeref(0) and
output.isParameterDeref(1)
or
// reverse flow from returned reference to first parameter
input.isReturnValueDeref() and
output.isParameterDeref(0)
}
}
/**
* The `std::basic_ostream` template class instantiations.
*/
private class StdBasicOStream extends ClassTemplateInstantiation {
StdBasicOStream() { this.hasQualifiedName(["std", "bsl"], "basic_ostream") }
}
private class StdStringLessThan extends Function, AliasFunction, SideEffectFunction {
StdStringLessThan() {
this.hasQualifiedName(["std", "bsl"], "operator<") and
this.getNumberOfParameters() = 2 and
this.getParameter(0).getUnspecifiedType().(ReferenceType).getBaseType() instanceof
StdBasicString and
this.getParameter(1).getUnspecifiedType().(ReferenceType).getBaseType() instanceof
StdBasicString
}
override predicate parameterNeverEscapes(int index) { index = [0, 1] }
override predicate parameterEscapesOnlyViaReturn(int index) { none() }
override predicate hasOnlySpecificReadSideEffects() { any() }
override predicate hasOnlySpecificWriteSideEffects() { any() }
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
none()
}
override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
i = [0, 1] and buffer = false
}
}
/**
* The `std::ostream` functions `operator<<` (defined as a member function),
* `put` and `write`.
*/
private class StdOStreamOut extends DataFlowFunction, TaintFunction {
StdOStreamOut() {
this.getClassAndName(["operator<<", "put", "write"]) instanceof StdBasicOStream
}
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// returns reference to `*this`
input.isQualifierAddress() and
output.isReturnValue()
or
input.isQualifierObject() and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter (value or pointer) to qualifier
input.isParameter(0) and
output.isQualifierObject()
or
input.isParameterDeref(0) and
output.isQualifierObject()
or
// flow from first parameter (value or pointer) to return value
input.isParameter(0) and
output.isReturnValueDeref()
or
input.isParameterDeref(0) and
output.isReturnValueDeref()
or
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
}
/**
* The `std::ostream` function `operator<<` (defined as a non-member function).
*/
private class StdOStreamOutNonMember extends DataFlowFunction, TaintFunction {
StdOStreamOutNonMember() {
this.hasQualifiedName(["std", "bsl"], "operator<<") and
this.getUnspecifiedType().(ReferenceType).getBaseType() instanceof StdBasicOStream
}
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// flow from first parameter to return value
input.isParameter(0) and
output.isReturnValue()
or
input.isParameterDeref(0) and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isParameterDeref(0) }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from second parameter to first parameter
input.isParameterDeref(1) and
output.isParameterDeref(0)
or
// flow from second parameter to return value
input.isParameterDeref(1) and
output.isReturnValueDeref()
or
// reverse flow from returned reference to the first parameter
input.isReturnValueDeref() and
output.isParameterDeref(0)
}
}
/**
* The `std::basic_stringstream` template class instantiations.
*/
private class StdBasicStringStream extends ClassTemplateInstantiation {
StdBasicStringStream() { this.hasQualifiedName(["std", "bsl"], "basic_stringstream") }
}
/**
* Additional model for `std::stringstream` constructors that take a string
* input parameter.
*/
private class StdStringStreamConstructor extends Constructor, TaintFunction {
StdStringStreamConstructor() { this.getDeclaringType() instanceof StdBasicStringStream }
/**
* Gets the index of a parameter to this function that is a string.
*/
int getAStringParameterIndex() {
this.getParameter(result).getType() instanceof ReferenceType // `const std::basic_string &`
}
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// taint flow from any parameter of string type to the returned object
input.isParameterDeref(this.getAStringParameterIndex()) and
(
output.isReturnValue() // TODO: this is only needed for AST data flow, which treats constructors as returning the new object
or
output.isQualifierObject()
)
}
}
/**
* The `std::stringstream` function `str`.
*/
private class StdStringStreamStr extends TaintFunction {
StdStringStreamStr() { this.getClassAndName("str") instanceof StdBasicStringStream }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// flow from qualifier to return value (if any)
input.isQualifierObject() and
output.isReturnValue()
or
// flow from first parameter (if any) to qualifier
input.isParameterDeref(0) and
output.isQualifierObject()
}
}
/**
* The `std::basic_ios` template class instantiations.
*/
private class StdBasicIOS extends ClassTemplateInstantiation {
StdBasicIOS() { this.hasQualifiedName(["std", "bsl"], "basic_ios") }
}
/**
* A `std::` stream function that does not require a model, except that it
* returns a reference to `*this` and thus could be used in a chain.
*/
private class StdStreamFunction extends DataFlowFunction, TaintFunction {
StdStreamFunction() {
this.getClassAndName(["ignore", "unget", "seekg"]) instanceof StdBasicIStream
or
this.getClassAndName(["seekp", "flush"]) instanceof StdBasicOStream
or
this.getClassAndName("copyfmt") instanceof StdBasicIOS
}
override predicate hasDataFlow(FunctionInput input, FunctionOutput output) {
// returns reference to `*this`
input.isQualifierAddress() and
output.isReturnValue()
or
input.isQualifierObject() and
output.isReturnValueDeref()
}
override predicate isPartialWrite(FunctionOutput output) { output.isQualifierObject() }
override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
// reverse flow from returned reference to the qualifier
input.isReturnValueDeref() and
output.isQualifierObject()
}
}