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codeql/python/ql/src/Variables/UndefinedExport.ql
2022-01-20 10:41:35 +01:00

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/**
* @name Explicit export is not defined
* @description Including an undefined attribute in `__all__` causes an exception when
* the module is imported using '*'
* @kind problem
* @tags reliability
* maintainability
* @problem.severity error
* @sub-severity low
* @precision high
* @id py/undefined-export
*/
import python
/** Whether name is declared in the __all__ list of this module */
predicate declaredInAll(Module m, StrConst name) {
exists(Assign a, GlobalVariable all |
a.defines(all) and
a.getScope() = m and
all.getId() = "__all__" and
a.getValue().(List).getAnElt() = name
)
}
predicate mutates_globals(ModuleValue m) {
exists(CallNode globals |
globals = Value::named("globals").(FunctionValue).getACall() and
globals.getScope() = m.getScope()
|
exists(AttrNode attr | attr.getObject() = globals)
or
exists(SubscriptNode sub | sub.getObject() = globals and sub.isStore())
)
or
// Enum (added in 3.4) has method `_convert_` that alters globals
// This was called `_convert` until 3.8, but that name will be removed in 3.9
exists(ClassValue enum_class |
enum_class.getASuperType() = Value::named("enum.Enum") and
(
// In Python < 3.8, Enum._convert can be found with points-to
exists(Value enum_convert |
enum_convert = enum_class.attr("_convert") and
exists(CallNode call | call.getScope() = m.getScope() |
enum_convert.getACall() = call or
call.getFunction().pointsTo(enum_convert)
)
)
or
// In Python 3.8, Enum._convert_ is implemented using a metaclass, and our points-to
// analysis doesn't handle that well enough. So we need a special case for this
not exists(enum_class.attr("_convert")) and
exists(CallNode call | call.getScope() = m.getScope() |
call.getFunction().(AttrNode).getObject(["_convert", "_convert_"]).pointsTo() = enum_class
)
)
)
}
predicate is_exported_submodule_name(ModuleValue m, string exported_name) {
m.getScope().getShortName() = "__init__" and
exists(m.getScope().getPackage().getSubModule(exported_name))
}
predicate contains_unknown_import_star(ModuleValue m) {
exists(ImportStarNode imp | imp.getEnclosingModule() = m.getScope() |
imp.getModule().pointsTo().isAbsent()
or
not exists(imp.getModule().pointsTo())
)
}
from ModuleValue m, StrConst name, string exported_name
where
declaredInAll(m.getScope(), name) and
exported_name = name.getText() and
not m.hasAttribute(exported_name) and
not is_exported_submodule_name(m, exported_name) and
not contains_unknown_import_star(m) and
not mutates_globals(m)
select name, "The name '" + exported_name + "' is exported by __all__ but is not defined."