| //==--- MacOSKeychainAPIChecker.cpp ------------------------------*- C++ -*-==// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // This checker flags misuses of KeyChainAPI. In particular, the password data |
| // allocated/returned by SecKeychainItemCopyContent, |
| // SecKeychainFindGenericPassword, SecKeychainFindInternetPassword functions has |
| // to be freed using a call to SecKeychainItemFreeContent. |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" |
| #include "clang/StaticAnalyzer/Core/Checker.h" |
| #include "clang/StaticAnalyzer/Core/CheckerManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| namespace { |
| class MacOSKeychainAPIChecker : public Checker<check::PreStmt<CallExpr>, |
| check::PostStmt<CallExpr>, |
| check::DeadSymbols, |
| check::PointerEscape, |
| eval::Assume> { |
| mutable std::unique_ptr<BugType> BT; |
| |
| public: |
| /// AllocationState is a part of the checker specific state together with the |
| /// MemRegion corresponding to the allocated data. |
| struct AllocationState { |
| /// The index of the allocator function. |
| unsigned int AllocatorIdx; |
| SymbolRef Region; |
| |
| AllocationState(const Expr *E, unsigned int Idx, SymbolRef R) : |
| AllocatorIdx(Idx), |
| Region(R) {} |
| |
| bool operator==(const AllocationState &X) const { |
| return (AllocatorIdx == X.AllocatorIdx && |
| Region == X.Region); |
| } |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const { |
| ID.AddInteger(AllocatorIdx); |
| ID.AddPointer(Region); |
| } |
| }; |
| |
| void checkPreStmt(const CallExpr *S, CheckerContext &C) const; |
| void checkPostStmt(const CallExpr *S, CheckerContext &C) const; |
| void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const; |
| ProgramStateRef checkPointerEscape(ProgramStateRef State, |
| const InvalidatedSymbols &Escaped, |
| const CallEvent *Call, |
| PointerEscapeKind Kind) const; |
| ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond, |
| bool Assumption) const; |
| void printState(raw_ostream &Out, ProgramStateRef State, |
| const char *NL, const char *Sep) const; |
| |
| private: |
| typedef std::pair<SymbolRef, const AllocationState*> AllocationPair; |
| typedef SmallVector<AllocationPair, 2> AllocationPairVec; |
| |
| enum APIKind { |
| /// Denotes functions tracked by this checker. |
| ValidAPI = 0, |
| /// The functions commonly/mistakenly used in place of the given API. |
| ErrorAPI = 1, |
| /// The functions which may allocate the data. These are tracked to reduce |
| /// the false alarm rate. |
| PossibleAPI = 2 |
| }; |
| /// Stores the information about the allocator and deallocator functions - |
| /// these are the functions the checker is tracking. |
| struct ADFunctionInfo { |
| const char* Name; |
| unsigned int Param; |
| unsigned int DeallocatorIdx; |
| APIKind Kind; |
| }; |
| static const unsigned InvalidIdx = 100000; |
| static const unsigned FunctionsToTrackSize = 8; |
| static const ADFunctionInfo FunctionsToTrack[FunctionsToTrackSize]; |
| /// The value, which represents no error return value for allocator functions. |
| static const unsigned NoErr = 0; |
| |
| /// Given the function name, returns the index of the allocator/deallocator |
| /// function. |
| static unsigned getTrackedFunctionIndex(StringRef Name, bool IsAllocator); |
| |
| inline void initBugType() const { |
| if (!BT) |
| BT.reset(new BugType(this, "Improper use of SecKeychain API", |
| "API Misuse (Apple)")); |
| } |
| |
| void generateDeallocatorMismatchReport(const AllocationPair &AP, |
| const Expr *ArgExpr, |
| CheckerContext &C) const; |
| |
| /// Find the allocation site for Sym on the path leading to the node N. |
| const ExplodedNode *getAllocationNode(const ExplodedNode *N, SymbolRef Sym, |
| CheckerContext &C) const; |
| |
| std::unique_ptr<BugReport> generateAllocatedDataNotReleasedReport( |
| const AllocationPair &AP, ExplodedNode *N, CheckerContext &C) const; |
| |
| /// Mark an AllocationPair interesting for diagnostic reporting. |
| void markInteresting(PathSensitiveBugReport *R, |
| const AllocationPair &AP) const { |
| R->markInteresting(AP.first); |
| R->markInteresting(AP.second->Region); |
| } |
| |
| /// The bug visitor which allows us to print extra diagnostics along the |
| /// BugReport path. For example, showing the allocation site of the leaked |
| /// region. |
| class SecKeychainBugVisitor : public BugReporterVisitor { |
| protected: |
| // The allocated region symbol tracked by the main analysis. |
| SymbolRef Sym; |
| |
| public: |
| SecKeychainBugVisitor(SymbolRef S) : Sym(S) {} |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const override { |
| static int X = 0; |
| ID.AddPointer(&X); |
| ID.AddPointer(Sym); |
| } |
| |
| PathDiagnosticPieceRef VisitNode(const ExplodedNode *N, |
| BugReporterContext &BRC, |
| PathSensitiveBugReport &BR) override; |
| }; |
| }; |
| } |
| |
| /// ProgramState traits to store the currently allocated (and not yet freed) |
| /// symbols. This is a map from the allocated content symbol to the |
| /// corresponding AllocationState. |
| REGISTER_MAP_WITH_PROGRAMSTATE(AllocatedData, |
| SymbolRef, |
| MacOSKeychainAPIChecker::AllocationState) |
| |
| static bool isEnclosingFunctionParam(const Expr *E) { |
| E = E->IgnoreParenCasts(); |
| if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) { |
| const ValueDecl *VD = DRE->getDecl(); |
| if (isa<ImplicitParamDecl>(VD) || isa<ParmVarDecl>(VD)) |
| return true; |
| } |
| return false; |
| } |
| |
| const MacOSKeychainAPIChecker::ADFunctionInfo |
| MacOSKeychainAPIChecker::FunctionsToTrack[FunctionsToTrackSize] = { |
| {"SecKeychainItemCopyContent", 4, 3, ValidAPI}, // 0 |
| {"SecKeychainFindGenericPassword", 6, 3, ValidAPI}, // 1 |
| {"SecKeychainFindInternetPassword", 13, 3, ValidAPI}, // 2 |
| {"SecKeychainItemFreeContent", 1, InvalidIdx, ValidAPI}, // 3 |
| {"SecKeychainItemCopyAttributesAndData", 5, 5, ValidAPI}, // 4 |
| {"SecKeychainItemFreeAttributesAndData", 1, InvalidIdx, ValidAPI}, // 5 |
| {"free", 0, InvalidIdx, ErrorAPI}, // 6 |
| {"CFStringCreateWithBytesNoCopy", 1, InvalidIdx, PossibleAPI}, // 7 |
| }; |
| |
| unsigned MacOSKeychainAPIChecker::getTrackedFunctionIndex(StringRef Name, |
| bool IsAllocator) { |
| for (unsigned I = 0; I < FunctionsToTrackSize; ++I) { |
| ADFunctionInfo FI = FunctionsToTrack[I]; |
| if (FI.Name != Name) |
| continue; |
| // Make sure the function is of the right type (allocator vs deallocator). |
| if (IsAllocator && (FI.DeallocatorIdx == InvalidIdx)) |
| return InvalidIdx; |
| if (!IsAllocator && (FI.DeallocatorIdx != InvalidIdx)) |
| return InvalidIdx; |
| |
| return I; |
| } |
| // The function is not tracked. |
| return InvalidIdx; |
| } |
| |
| static bool isBadDeallocationArgument(const MemRegion *Arg) { |
| if (!Arg) |
| return false; |
| return isa<AllocaRegion>(Arg) || isa<BlockDataRegion>(Arg) || |
| isa<TypedRegion>(Arg); |
| } |
| |
| /// Given the address expression, retrieve the value it's pointing to. Assume |
| /// that value is itself an address, and return the corresponding symbol. |
| static SymbolRef getAsPointeeSymbol(const Expr *Expr, |
| CheckerContext &C) { |
| ProgramStateRef State = C.getState(); |
| SVal ArgV = C.getSVal(Expr); |
| |
| if (Optional<loc::MemRegionVal> X = ArgV.getAs<loc::MemRegionVal>()) { |
| StoreManager& SM = C.getStoreManager(); |
| SymbolRef sym = SM.getBinding(State->getStore(), *X).getAsLocSymbol(); |
| if (sym) |
| return sym; |
| } |
| return nullptr; |
| } |
| |
| // Report deallocator mismatch. Remove the region from tracking - reporting a |
| // missing free error after this one is redundant. |
| void MacOSKeychainAPIChecker:: |
| generateDeallocatorMismatchReport(const AllocationPair &AP, |
| const Expr *ArgExpr, |
| CheckerContext &C) const { |
| ProgramStateRef State = C.getState(); |
| State = State->remove<AllocatedData>(AP.first); |
| ExplodedNode *N = C.generateNonFatalErrorNode(State); |
| |
| if (!N) |
| return; |
| initBugType(); |
| SmallString<80> sbuf; |
| llvm::raw_svector_ostream os(sbuf); |
| unsigned int PDeallocIdx = |
| FunctionsToTrack[AP.second->AllocatorIdx].DeallocatorIdx; |
| |
| os << "Deallocator doesn't match the allocator: '" |
| << FunctionsToTrack[PDeallocIdx].Name << "' should be used."; |
| auto Report = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N); |
| Report->addVisitor(std::make_unique<SecKeychainBugVisitor>(AP.first)); |
| Report->addRange(ArgExpr->getSourceRange()); |
| markInteresting(Report.get(), AP); |
| C.emitReport(std::move(Report)); |
| } |
| |
| void MacOSKeychainAPIChecker::checkPreStmt(const CallExpr *CE, |
| CheckerContext &C) const { |
| unsigned idx = InvalidIdx; |
| ProgramStateRef State = C.getState(); |
| |
| const FunctionDecl *FD = C.getCalleeDecl(CE); |
| if (!FD || FD->getKind() != Decl::Function) |
| return; |
| |
| StringRef funName = C.getCalleeName(FD); |
| if (funName.empty()) |
| return; |
| |
| // If it is a call to an allocator function, it could be a double allocation. |
| idx = getTrackedFunctionIndex(funName, true); |
| if (idx != InvalidIdx) { |
| unsigned paramIdx = FunctionsToTrack[idx].Param; |
| if (CE->getNumArgs() <= paramIdx) |
| return; |
| |
| const Expr *ArgExpr = CE->getArg(paramIdx); |
| if (SymbolRef V = getAsPointeeSymbol(ArgExpr, C)) |
| if (const AllocationState *AS = State->get<AllocatedData>(V)) { |
| // Remove the value from the state. The new symbol will be added for |
| // tracking when the second allocator is processed in checkPostStmt(). |
| State = State->remove<AllocatedData>(V); |
| ExplodedNode *N = C.generateNonFatalErrorNode(State); |
| if (!N) |
| return; |
| initBugType(); |
| SmallString<128> sbuf; |
| llvm::raw_svector_ostream os(sbuf); |
| unsigned int DIdx = FunctionsToTrack[AS->AllocatorIdx].DeallocatorIdx; |
| os << "Allocated data should be released before another call to " |
| << "the allocator: missing a call to '" |
| << FunctionsToTrack[DIdx].Name |
| << "'."; |
| auto Report = |
| std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N); |
| Report->addVisitor(std::make_unique<SecKeychainBugVisitor>(V)); |
| Report->addRange(ArgExpr->getSourceRange()); |
| Report->markInteresting(AS->Region); |
| C.emitReport(std::move(Report)); |
| } |
| return; |
| } |
| |
| // Is it a call to one of deallocator functions? |
| idx = getTrackedFunctionIndex(funName, false); |
| if (idx == InvalidIdx) |
| return; |
| |
| unsigned paramIdx = FunctionsToTrack[idx].Param; |
| if (CE->getNumArgs() <= paramIdx) |
| return; |
| |
| // Check the argument to the deallocator. |
| const Expr *ArgExpr = CE->getArg(paramIdx); |
| SVal ArgSVal = C.getSVal(ArgExpr); |
| |
| // Undef is reported by another checker. |
| if (ArgSVal.isUndef()) |
| return; |
| |
| SymbolRef ArgSM = ArgSVal.getAsLocSymbol(); |
| |
| // If the argument is coming from the heap, globals, or unknown, do not |
| // report it. |
| bool RegionArgIsBad = false; |
| if (!ArgSM) { |
| if (!isBadDeallocationArgument(ArgSVal.getAsRegion())) |
| return; |
| RegionArgIsBad = true; |
| } |
| |
| // Is the argument to the call being tracked? |
| const AllocationState *AS = State->get<AllocatedData>(ArgSM); |
| if (!AS) |
| return; |
| |
| // TODO: We might want to report double free here. |
| // (that would involve tracking all the freed symbols in the checker state). |
| if (RegionArgIsBad) { |
| // It is possible that this is a false positive - the argument might |
| // have entered as an enclosing function parameter. |
| if (isEnclosingFunctionParam(ArgExpr)) |
| return; |
| |
| ExplodedNode *N = C.generateNonFatalErrorNode(State); |
| if (!N) |
| return; |
| initBugType(); |
| auto Report = std::make_unique<PathSensitiveBugReport>( |
| *BT, "Trying to free data which has not been allocated.", N); |
| Report->addRange(ArgExpr->getSourceRange()); |
| if (AS) |
| Report->markInteresting(AS->Region); |
| C.emitReport(std::move(Report)); |
| return; |
| } |
| |
| // Process functions which might deallocate. |
| if (FunctionsToTrack[idx].Kind == PossibleAPI) { |
| |
| if (funName == "CFStringCreateWithBytesNoCopy") { |
| const Expr *DeallocatorExpr = CE->getArg(5)->IgnoreParenCasts(); |
| // NULL ~ default deallocator, so warn. |
| if (DeallocatorExpr->isNullPointerConstant(C.getASTContext(), |
| Expr::NPC_ValueDependentIsNotNull)) { |
| const AllocationPair AP = std::make_pair(ArgSM, AS); |
| generateDeallocatorMismatchReport(AP, ArgExpr, C); |
| return; |
| } |
| // One of the default allocators, so warn. |
| if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(DeallocatorExpr)) { |
| StringRef DeallocatorName = DE->getFoundDecl()->getName(); |
| if (DeallocatorName == "kCFAllocatorDefault" || |
| DeallocatorName == "kCFAllocatorSystemDefault" || |
| DeallocatorName == "kCFAllocatorMalloc") { |
| const AllocationPair AP = std::make_pair(ArgSM, AS); |
| generateDeallocatorMismatchReport(AP, ArgExpr, C); |
| return; |
| } |
| // If kCFAllocatorNull, which does not deallocate, we still have to |
| // find the deallocator. |
| if (DE->getFoundDecl()->getName() == "kCFAllocatorNull") |
| return; |
| } |
| // In all other cases, assume the user supplied a correct deallocator |
| // that will free memory so stop tracking. |
| State = State->remove<AllocatedData>(ArgSM); |
| C.addTransition(State); |
| return; |
| } |
| |
| llvm_unreachable("We know of no other possible APIs."); |
| } |
| |
| // The call is deallocating a value we previously allocated, so remove it |
| // from the next state. |
| State = State->remove<AllocatedData>(ArgSM); |
| |
| // Check if the proper deallocator is used. |
| unsigned int PDeallocIdx = FunctionsToTrack[AS->AllocatorIdx].DeallocatorIdx; |
| if (PDeallocIdx != idx || (FunctionsToTrack[idx].Kind == ErrorAPI)) { |
| const AllocationPair AP = std::make_pair(ArgSM, AS); |
| generateDeallocatorMismatchReport(AP, ArgExpr, C); |
| return; |
| } |
| |
| C.addTransition(State); |
| } |
| |
| void MacOSKeychainAPIChecker::checkPostStmt(const CallExpr *CE, |
| CheckerContext &C) const { |
| ProgramStateRef State = C.getState(); |
| const FunctionDecl *FD = C.getCalleeDecl(CE); |
| if (!FD || FD->getKind() != Decl::Function) |
| return; |
| |
| StringRef funName = C.getCalleeName(FD); |
| |
| // If a value has been allocated, add it to the set for tracking. |
| unsigned idx = getTrackedFunctionIndex(funName, true); |
| if (idx == InvalidIdx) |
| return; |
| |
| const Expr *ArgExpr = CE->getArg(FunctionsToTrack[idx].Param); |
| // If the argument entered as an enclosing function parameter, skip it to |
| // avoid false positives. |
| if (isEnclosingFunctionParam(ArgExpr) && |
| C.getLocationContext()->getParent() == nullptr) |
| return; |
| |
| if (SymbolRef V = getAsPointeeSymbol(ArgExpr, C)) { |
| // If the argument points to something that's not a symbolic region, it |
| // can be: |
| // - unknown (cannot reason about it) |
| // - undefined (already reported by other checker) |
| // - constant (null - should not be tracked, |
| // other constant will generate a compiler warning) |
| // - goto (should be reported by other checker) |
| |
| // The call return value symbol should stay alive for as long as the |
| // allocated value symbol, since our diagnostics depend on the value |
| // returned by the call. Ex: Data should only be freed if noErr was |
| // returned during allocation.) |
| SymbolRef RetStatusSymbol = C.getSVal(CE).getAsSymbol(); |
| C.getSymbolManager().addSymbolDependency(V, RetStatusSymbol); |
| |
| // Track the allocated value in the checker state. |
| State = State->set<AllocatedData>(V, AllocationState(ArgExpr, idx, |
| RetStatusSymbol)); |
| assert(State); |
| C.addTransition(State); |
| } |
| } |
| |
| // TODO: This logic is the same as in Malloc checker. |
| const ExplodedNode * |
| MacOSKeychainAPIChecker::getAllocationNode(const ExplodedNode *N, |
| SymbolRef Sym, |
| CheckerContext &C) const { |
| const LocationContext *LeakContext = N->getLocationContext(); |
| // Walk the ExplodedGraph backwards and find the first node that referred to |
| // the tracked symbol. |
| const ExplodedNode *AllocNode = N; |
| |
| while (N) { |
| if (!N->getState()->get<AllocatedData>(Sym)) |
| break; |
| // Allocation node, is the last node in the current or parent context in |
| // which the symbol was tracked. |
| const LocationContext *NContext = N->getLocationContext(); |
| if (NContext == LeakContext || |
| NContext->isParentOf(LeakContext)) |
| AllocNode = N; |
| N = N->pred_empty() ? nullptr : *(N->pred_begin()); |
| } |
| |
| return AllocNode; |
| } |
| |
| std::unique_ptr<BugReport> |
| MacOSKeychainAPIChecker::generateAllocatedDataNotReleasedReport( |
| const AllocationPair &AP, ExplodedNode *N, CheckerContext &C) const { |
| const ADFunctionInfo &FI = FunctionsToTrack[AP.second->AllocatorIdx]; |
| initBugType(); |
| SmallString<70> sbuf; |
| llvm::raw_svector_ostream os(sbuf); |
| os << "Allocated data is not released: missing a call to '" |
| << FunctionsToTrack[FI.DeallocatorIdx].Name << "'."; |
| |
| // Most bug reports are cached at the location where they occurred. |
| // With leaks, we want to unique them by the location where they were |
| // allocated, and only report a single path. |
| PathDiagnosticLocation LocUsedForUniqueing; |
| const ExplodedNode *AllocNode = getAllocationNode(N, AP.first, C); |
| const Stmt *AllocStmt = AllocNode->getStmtForDiagnostics(); |
| |
| if (AllocStmt) |
| LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocStmt, |
| C.getSourceManager(), |
| AllocNode->getLocationContext()); |
| |
| auto Report = std::make_unique<PathSensitiveBugReport>( |
| *BT, os.str(), N, LocUsedForUniqueing, |
| AllocNode->getLocationContext()->getDecl()); |
| |
| Report->addVisitor(std::make_unique<SecKeychainBugVisitor>(AP.first)); |
| markInteresting(Report.get(), AP); |
| return Report; |
| } |
| |
| /// If the return symbol is assumed to be error, remove the allocated info |
| /// from consideration. |
| ProgramStateRef MacOSKeychainAPIChecker::evalAssume(ProgramStateRef State, |
| SVal Cond, |
| bool Assumption) const { |
| AllocatedDataTy AMap = State->get<AllocatedData>(); |
| if (AMap.isEmpty()) |
| return State; |
| |
| auto *CondBSE = dyn_cast_or_null<BinarySymExpr>(Cond.getAsSymExpr()); |
| if (!CondBSE) |
| return State; |
| BinaryOperator::Opcode OpCode = CondBSE->getOpcode(); |
| if (OpCode != BO_EQ && OpCode != BO_NE) |
| return State; |
| |
| // Match for a restricted set of patterns for cmparison of error codes. |
| // Note, the comparisons of type '0 == st' are transformed into SymIntExpr. |
| SymbolRef ReturnSymbol = nullptr; |
| if (auto *SIE = dyn_cast<SymIntExpr>(CondBSE)) { |
| const llvm::APInt &RHS = SIE->getRHS(); |
| bool ErrorIsReturned = (OpCode == BO_EQ && RHS != NoErr) || |
| (OpCode == BO_NE && RHS == NoErr); |
| if (!Assumption) |
| ErrorIsReturned = !ErrorIsReturned; |
| if (ErrorIsReturned) |
| ReturnSymbol = SIE->getLHS(); |
| } |
| |
| if (ReturnSymbol) |
| for (auto I = AMap.begin(), E = AMap.end(); I != E; ++I) { |
| if (ReturnSymbol == I->second.Region) |
| State = State->remove<AllocatedData>(I->first); |
| } |
| |
| return State; |
| } |
| |
| void MacOSKeychainAPIChecker::checkDeadSymbols(SymbolReaper &SR, |
| CheckerContext &C) const { |
| ProgramStateRef State = C.getState(); |
| AllocatedDataTy AMap = State->get<AllocatedData>(); |
| if (AMap.isEmpty()) |
| return; |
| |
| bool Changed = false; |
| AllocationPairVec Errors; |
| for (auto I = AMap.begin(), E = AMap.end(); I != E; ++I) { |
| if (!SR.isDead(I->first)) |
| continue; |
| |
| Changed = true; |
| State = State->remove<AllocatedData>(I->first); |
| // If the allocated symbol is null do not report. |
| ConstraintManager &CMgr = State->getConstraintManager(); |
| ConditionTruthVal AllocFailed = CMgr.isNull(State, I.getKey()); |
| if (AllocFailed.isConstrainedTrue()) |
| continue; |
| Errors.push_back(std::make_pair(I->first, &I->second)); |
| } |
| if (!Changed) { |
| // Generate the new, cleaned up state. |
| C.addTransition(State); |
| return; |
| } |
| |
| static CheckerProgramPointTag Tag(this, "DeadSymbolsLeak"); |
| ExplodedNode *N = C.generateNonFatalErrorNode(C.getState(), &Tag); |
| if (!N) |
| return; |
| |
| // Generate the error reports. |
| for (const auto &P : Errors) |
| C.emitReport(generateAllocatedDataNotReleasedReport(P, N, C)); |
| |
| // Generate the new, cleaned up state. |
| C.addTransition(State, N); |
| } |
| |
| ProgramStateRef MacOSKeychainAPIChecker::checkPointerEscape( |
| ProgramStateRef State, const InvalidatedSymbols &Escaped, |
| const CallEvent *Call, PointerEscapeKind Kind) const { |
| // FIXME: This branch doesn't make any sense at all, but it is an overfitted |
| // replacement for a previous overfitted code that was making even less sense. |
| if (!Call || Call->getDecl()) |
| return State; |
| |
| for (auto I : State->get<AllocatedData>()) { |
| SymbolRef Sym = I.first; |
| if (Escaped.count(Sym)) |
| State = State->remove<AllocatedData>(Sym); |
| |
| // This checker is special. Most checkers in fact only track symbols of |
| // SymbolConjured type, eg. symbols returned from functions such as |
| // malloc(). This checker tracks symbols returned as out-parameters. |
| // |
| // When a function is evaluated conservatively, the out-parameter's pointee |
| // base region gets invalidated with a SymbolConjured. If the base region is |
| // larger than the region we're interested in, the value we're interested in |
| // would be SymbolDerived based on that SymbolConjured. However, such |
| // SymbolDerived will never be listed in the Escaped set when the base |
| // region is invalidated because ExprEngine doesn't know which symbols |
| // were derived from a given symbol, while there can be infinitely many |
| // valid symbols derived from any given symbol. |
| // |
| // Hence the extra boilerplate: remove the derived symbol when its parent |
| // symbol escapes. |
| // |
| if (const auto *SD = dyn_cast<SymbolDerived>(Sym)) { |
| SymbolRef ParentSym = SD->getParentSymbol(); |
| if (Escaped.count(ParentSym)) |
| State = State->remove<AllocatedData>(Sym); |
| } |
| } |
| return State; |
| } |
| |
| PathDiagnosticPieceRef |
| MacOSKeychainAPIChecker::SecKeychainBugVisitor::VisitNode( |
| const ExplodedNode *N, BugReporterContext &BRC, |
| PathSensitiveBugReport &BR) { |
| const AllocationState *AS = N->getState()->get<AllocatedData>(Sym); |
| if (!AS) |
| return nullptr; |
| const AllocationState *ASPrev = |
| N->getFirstPred()->getState()->get<AllocatedData>(Sym); |
| if (ASPrev) |
| return nullptr; |
| |
| // (!ASPrev && AS) ~ We started tracking symbol in node N, it must be the |
| // allocation site. |
| const CallExpr *CE = |
| cast<CallExpr>(N->getLocation().castAs<StmtPoint>().getStmt()); |
| const FunctionDecl *funDecl = CE->getDirectCallee(); |
| assert(funDecl && "We do not support indirect function calls as of now."); |
| StringRef funName = funDecl->getName(); |
| |
| // Get the expression of the corresponding argument. |
| unsigned Idx = getTrackedFunctionIndex(funName, true); |
| assert(Idx != InvalidIdx && "This should be a call to an allocator."); |
| const Expr *ArgExpr = CE->getArg(FunctionsToTrack[Idx].Param); |
| PathDiagnosticLocation Pos(ArgExpr, BRC.getSourceManager(), |
| N->getLocationContext()); |
| return std::make_shared<PathDiagnosticEventPiece>(Pos, |
| "Data is allocated here."); |
| } |
| |
| void MacOSKeychainAPIChecker::printState(raw_ostream &Out, |
| ProgramStateRef State, |
| const char *NL, |
| const char *Sep) const { |
| |
| AllocatedDataTy AMap = State->get<AllocatedData>(); |
| |
| if (!AMap.isEmpty()) { |
| Out << Sep << "KeychainAPIChecker :" << NL; |
| for (auto I = AMap.begin(), E = AMap.end(); I != E; ++I) { |
| I.getKey()->dumpToStream(Out); |
| } |
| } |
| } |
| |
| |
| void ento::registerMacOSKeychainAPIChecker(CheckerManager &mgr) { |
| mgr.registerChecker<MacOSKeychainAPIChecker>(); |
| } |
| |
| bool ento::shouldRegisterMacOSKeychainAPIChecker(const LangOptions &LO) { |
| return true; |
| } |