1 //===- OSObjectCStyleCast.cpp ------------------------------------*- C++ -*-==// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines OSObjectCStyleCast checker, which checks for C-style casts 10 // of OSObjects. Such casts almost always indicate a code smell, 11 // as an explicit static or dynamic cast should be used instead. 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" 15 #include "clang/ASTMatchers/ASTMatchFinder.h" 16 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h" 17 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 18 #include "clang/StaticAnalyzer/Core/Checker.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h" 20 #include "llvm/Support/Debug.h" 21 22 using namespace clang; 23 using namespace ento; 24 using namespace ast_matchers; 25 26 namespace { 27 28 const char *WarnAtNode = "OSObjCast"; 29 30 class OSObjectCStyleCastChecker : public Checker<check::ASTCodeBody> { 31 public: 32 void checkASTCodeBody(const Decl *D, 33 AnalysisManager &AM, 34 BugReporter &BR) const; 35 }; 36 37 static void emitDiagnostics(const BoundNodes &Nodes, 38 BugReporter &BR, 39 AnalysisDeclContext *ADC, 40 const OSObjectCStyleCastChecker *Checker) { 41 const auto *CE = Nodes.getNodeAs<CastExpr>(WarnAtNode); 42 assert(CE); 43 44 std::string Diagnostics; 45 llvm::raw_string_ostream OS(Diagnostics); 46 OS << "C-style cast of OSObject. Use OSDynamicCast instead."; 47 48 BR.EmitBasicReport( 49 ADC->getDecl(), 50 Checker, 51 /*Name=*/"OSObject C-Style Cast", 52 /*BugCategory=*/"Security", 53 OS.str(), 54 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), ADC), 55 CE->getSourceRange()); 56 } 57 58 static decltype(auto) hasTypePointingTo(DeclarationMatcher DeclM) { 59 return hasType(pointerType(pointee(hasDeclaration(DeclM)))); 60 } 61 62 void OSObjectCStyleCastChecker::checkASTCodeBody(const Decl *D, AnalysisManager &AM, 63 BugReporter &BR) const { 64 65 AnalysisDeclContext *ADC = AM.getAnalysisDeclContext(D); 66 67 auto DynamicCastM = callExpr(callee(functionDecl(hasName("safeMetaCast")))); 68 69 auto OSObjTypeM = hasTypePointingTo(cxxRecordDecl(isDerivedFrom("OSMetaClassBase"))); 70 auto OSObjSubclassM = hasTypePointingTo( 71 cxxRecordDecl(isDerivedFrom("OSObject"))); 72 73 auto CastM = cStyleCastExpr( 74 allOf(hasSourceExpression(allOf(OSObjTypeM, unless(DynamicCastM))), 75 OSObjSubclassM)).bind(WarnAtNode); 76 77 auto Matches = match(stmt(forEachDescendant(CastM)), *D->getBody(), AM.getASTContext()); 78 for (BoundNodes Match : Matches) 79 emitDiagnostics(Match, BR, ADC, this); 80 } 81 } 82 83 void ento::registerOSObjectCStyleCast(CheckerManager &Mgr) { 84 Mgr.registerChecker<OSObjectCStyleCastChecker>(); 85 } 86 87 bool ento::shouldRegisterOSObjectCStyleCast(const CheckerManager &mgr) { 88 return true; 89 } 90