93 lines
3.5 KiB
C++
93 lines
3.5 KiB
C++
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//===- OSObjectCStyleCast.cpp ------------------------------------*- C++ -*-==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines OSObjectCStyleCast checker, which checks for C-style casts
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// of OSObjects. Such casts almost always indicate a code smell,
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// as an explicit static or dynamic cast should be used instead.
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//===----------------------------------------------------------------------===//
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#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
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#include "llvm/Support/Debug.h"
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using namespace clang;
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using namespace ento;
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using namespace ast_matchers;
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namespace {
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static constexpr const char *const WarnAtNode = "WarnAtNode";
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static constexpr const char *const WarnRecordDecl = "WarnRecordDecl";
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class OSObjectCStyleCastChecker : public Checker<check::ASTCodeBody> {
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public:
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void checkASTCodeBody(const Decl *D, AnalysisManager &AM,
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BugReporter &BR) const;
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};
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}
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static void emitDiagnostics(const BoundNodes &Nodes,
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BugReporter &BR,
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AnalysisDeclContext *ADC,
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const OSObjectCStyleCastChecker *Checker) {
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const auto *CE = Nodes.getNodeAs<CastExpr>(WarnAtNode);
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const CXXRecordDecl *RD = Nodes.getNodeAs<CXXRecordDecl>(WarnRecordDecl);
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assert(CE && RD);
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std::string Diagnostics;
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llvm::raw_string_ostream OS(Diagnostics);
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OS << "C-style cast of an OSObject is prone to type confusion attacks; "
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<< "use 'OSRequiredCast' if the object is definitely of type '"
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<< RD->getNameAsString() << "', or 'OSDynamicCast' followed by "
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<< "a null check if unsure",
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BR.EmitBasicReport(
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ADC->getDecl(),
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Checker,
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/*Name=*/"OSObject C-Style Cast",
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categories::SecurityError,
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OS.str(),
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PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), ADC),
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CE->getSourceRange());
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}
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static decltype(auto) hasTypePointingTo(DeclarationMatcher DeclM) {
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return hasType(pointerType(pointee(hasDeclaration(DeclM))));
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}
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void OSObjectCStyleCastChecker::checkASTCodeBody(const Decl *D, AnalysisManager &AM,
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BugReporter &BR) const {
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AnalysisDeclContext *ADC = AM.getAnalysisDeclContext(D);
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auto DynamicCastM = callExpr(callee(functionDecl(hasName("safeMetaCast"))));
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auto OSObjTypeM = hasTypePointingTo(cxxRecordDecl(isDerivedFrom("OSMetaClassBase")));
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auto OSObjSubclassM = hasTypePointingTo(
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cxxRecordDecl(isDerivedFrom("OSObject")).bind(WarnRecordDecl));
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auto CastM = cStyleCastExpr(
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allOf(hasSourceExpression(allOf(OSObjTypeM, unless(DynamicCastM))),
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OSObjSubclassM)).bind(WarnAtNode);
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auto Matches = match(stmt(forEachDescendant(CastM)), *D->getBody(), AM.getASTContext());
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for (BoundNodes Match : Matches)
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emitDiagnostics(Match, BR, ADC, this);
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}
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void ento::registerOSObjectCStyleCast(CheckerManager &Mgr) {
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Mgr.registerChecker<OSObjectCStyleCastChecker>();
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}
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bool ento::shouldRegisterOSObjectCStyleCast(const CheckerManager &mgr) {
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return true;
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}
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