Index: lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp =================================================================== --- lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp +++ lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp @@ -22,6 +22,8 @@ #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" #include +#include +#include using namespace clang; using namespace ento; @@ -45,7 +47,7 @@ static const unsigned ReturnValueIndex = UINT_MAX - 1; mutable std::unique_ptr BT; - inline void initBugType() const { + void initBugType() const { if (!BT) BT.reset(new BugType(this, "Use of Untrusted Data", "Untrusted Data")); } @@ -71,7 +73,7 @@ static Optional getPointedToSVal(CheckerContext &C, const Expr *Arg); /// Functions defining the attack surface. - typedef ProgramStateRef (GenericTaintChecker::*FnCheck)( + using FnCheck = ProgramStateRef (GenericTaintChecker::*)( const CallExpr *, CheckerContext &C) const; ProgramStateRef postScanf(const CallExpr *CE, CheckerContext &C) const; ProgramStateRef postSocket(const CallExpr *CE, CheckerContext &C) const; @@ -102,7 +104,7 @@ bool generateReportIfTainted(const Expr *E, const char Msg[], CheckerContext &C) const; - typedef SmallVector ArgVector; + using ArgVector = SmallVector; /// A struct used to specify taint propagation rules for a function. /// @@ -114,48 +116,47 @@ /// ReturnValueIndex is added to the dst list, the return value will be /// tainted. struct TaintPropagationRule { + enum class VariadicType { None, Src, Dst }; + /// List of arguments which can be taint sources and should be checked. ArgVector SrcArgs; /// List of arguments which should be tainted on function return. ArgVector DstArgs; - // TODO: Check if using other data structures would be more optimal. - - TaintPropagationRule() {} - - TaintPropagationRule(unsigned SArg, unsigned DArg, bool TaintRet = false) { - SrcArgs.push_back(SArg); - DstArgs.push_back(DArg); - if (TaintRet) - DstArgs.push_back(ReturnValueIndex); - } - - TaintPropagationRule(unsigned SArg1, unsigned SArg2, unsigned DArg, - bool TaintRet = false) { - SrcArgs.push_back(SArg1); - SrcArgs.push_back(SArg2); - DstArgs.push_back(DArg); - if (TaintRet) - DstArgs.push_back(ReturnValueIndex); - } + /// Index for the first variadic parameter if exist. + unsigned VariadicIndex; + /// Show when a function has variadic parameters. If it has, it marks all + /// of them as source or destination. + VariadicType VarType; + + TaintPropagationRule() + : VariadicIndex(InvalidArgIndex), VarType(VariadicType::None) {} + + TaintPropagationRule(std::initializer_list &&Src, + std::initializer_list &&Dst, + VariadicType Var = VariadicType::None, + unsigned VarIndex = InvalidArgIndex) + : SrcArgs(std::move(Src)), DstArgs(std::move(Dst)), + VariadicIndex(VarIndex), VarType(Var) {} /// Get the propagation rule for a given function. static TaintPropagationRule getTaintPropagationRule(const FunctionDecl *FDecl, StringRef Name, CheckerContext &C); - inline void addSrcArg(unsigned A) { SrcArgs.push_back(A); } - inline void addDstArg(unsigned A) { DstArgs.push_back(A); } + void addSrcArg(unsigned A) { SrcArgs.push_back(A); } + void addDstArg(unsigned A) { DstArgs.push_back(A); } - inline bool isNull() const { return SrcArgs.empty(); } + bool isNull() const { + return SrcArgs.empty() && DstArgs.empty() && + VariadicType::None == VarType; + } - inline bool isDestinationArgument(unsigned ArgNum) const { - return (std::find(DstArgs.begin(), DstArgs.end(), ArgNum) != - DstArgs.end()); + bool isDestinationArgument(unsigned ArgNum) const { + return (llvm::find(DstArgs, ArgNum) != DstArgs.end()); } - static inline bool isTaintedOrPointsToTainted(const Expr *E, - ProgramStateRef State, - CheckerContext &C) { + static bool isTaintedOrPointsToTainted(const Expr *E, ProgramStateRef State, + CheckerContext &C) { if (State->isTainted(E, C.getLocationContext()) || isStdin(E, C)) return true; @@ -186,8 +187,7 @@ const char GenericTaintChecker::MsgTaintedBufferSize[] = "Untrusted data is used to specify the buffer size " "(CERT/STR31-C. Guarantee that storage for strings has sufficient space " - "for " - "character data and the null terminator)"; + "for character data and the null terminator)"; } // end of anonymous namespace @@ -206,24 +206,25 @@ // Check for exact name match for functions without builtin substitutes. TaintPropagationRule Rule = llvm::StringSwitch(Name) - .Case("atoi", TaintPropagationRule(0, ReturnValueIndex)) - .Case("atol", TaintPropagationRule(0, ReturnValueIndex)) - .Case("atoll", TaintPropagationRule(0, ReturnValueIndex)) - .Case("getc", TaintPropagationRule(0, ReturnValueIndex)) - .Case("fgetc", TaintPropagationRule(0, ReturnValueIndex)) - .Case("getc_unlocked", TaintPropagationRule(0, ReturnValueIndex)) - .Case("getw", TaintPropagationRule(0, ReturnValueIndex)) - .Case("toupper", TaintPropagationRule(0, ReturnValueIndex)) - .Case("tolower", TaintPropagationRule(0, ReturnValueIndex)) - .Case("strchr", TaintPropagationRule(0, ReturnValueIndex)) - .Case("strrchr", TaintPropagationRule(0, ReturnValueIndex)) - .Case("read", TaintPropagationRule(0, 2, 1, true)) - .Case("pread", TaintPropagationRule(InvalidArgIndex, 1, true)) - .Case("gets", TaintPropagationRule(InvalidArgIndex, 0, true)) - .Case("fgets", TaintPropagationRule(2, 0, true)) - .Case("getline", TaintPropagationRule(2, 0)) - .Case("getdelim", TaintPropagationRule(3, 0)) - .Case("fgetln", TaintPropagationRule(0, ReturnValueIndex)) + .Case("atoi", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("atol", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("atoll", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("getc", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("fgetc", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("getc_unlocked", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("getw", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("toupper", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("tolower", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("strchr", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("strrchr", TaintPropagationRule({0}, {ReturnValueIndex})) + .Case("read", TaintPropagationRule({0, 2}, {1, ReturnValueIndex})) + .Case("pread", + TaintPropagationRule({0, 1, 2, 3}, {1, ReturnValueIndex})) + .Case("gets", TaintPropagationRule({}, {0, ReturnValueIndex})) + .Case("fgets", TaintPropagationRule({2}, {0, ReturnValueIndex})) + .Case("getline", TaintPropagationRule({2}, {0})) + .Case("getdelim", TaintPropagationRule({3}, {0})) + .Case("fgetln", TaintPropagationRule({0}, {ReturnValueIndex})) .Default(TaintPropagationRule()); if (!Rule.isNull()) @@ -238,12 +239,12 @@ case Builtin::BImemmove: case Builtin::BIstrncpy: case Builtin::BIstrncat: - return TaintPropagationRule(1, 2, 0, true); + return TaintPropagationRule({1, 2}, {0, ReturnValueIndex}); case Builtin::BIstrlcpy: case Builtin::BIstrlcat: - return TaintPropagationRule(1, 2, 0, false); + return TaintPropagationRule({1, 2}, {0}); case Builtin::BIstrndup: - return TaintPropagationRule(0, 1, ReturnValueIndex); + return TaintPropagationRule({0, 1}, {ReturnValueIndex}); default: break; @@ -251,20 +252,23 @@ // Process all other functions which could be defined as builtins. if (Rule.isNull()) { - if (C.isCLibraryFunction(FDecl, "snprintf") || - C.isCLibraryFunction(FDecl, "sprintf")) - return TaintPropagationRule(InvalidArgIndex, 0, true); + if (C.isCLibraryFunction(FDecl, "snprintf")) + return TaintPropagationRule({1}, {0, ReturnValueIndex}, VariadicType::Src, + 3); + else if (C.isCLibraryFunction(FDecl, "sprintf")) + return TaintPropagationRule({}, {0, ReturnValueIndex}, VariadicType::Src, + 2); else if (C.isCLibraryFunction(FDecl, "strcpy") || C.isCLibraryFunction(FDecl, "stpcpy") || C.isCLibraryFunction(FDecl, "strcat")) - return TaintPropagationRule(1, 0, true); + return TaintPropagationRule({1}, {0, ReturnValueIndex}); else if (C.isCLibraryFunction(FDecl, "bcopy")) - return TaintPropagationRule(0, 2, 1, false); + return TaintPropagationRule({0, 2}, {1}); else if (C.isCLibraryFunction(FDecl, "strdup") || C.isCLibraryFunction(FDecl, "strdupa")) - return TaintPropagationRule(0, ReturnValueIndex); + return TaintPropagationRule({0}, {ReturnValueIndex}); else if (C.isCLibraryFunction(FDecl, "wcsdup")) - return TaintPropagationRule(0, ReturnValueIndex); + return TaintPropagationRule({0}, {ReturnValueIndex}); } // Skipping the following functions, since they might be used for cleansing @@ -336,11 +340,7 @@ if (TaintArgs.isEmpty()) return false; - for (llvm::ImmutableSet::iterator I = TaintArgs.begin(), - E = TaintArgs.end(); - I != E; ++I) { - unsigned ArgNum = *I; - + for (unsigned ArgNum : TaintArgs) { // Special handling for the tainted return value. if (ArgNum == ReturnValueIndex) { State = State->addTaint(CE, C.getLocationContext()); @@ -459,53 +459,27 @@ // Check for taint in arguments. bool IsTainted = false; - for (ArgVector::const_iterator I = SrcArgs.begin(), E = SrcArgs.end(); I != E; - ++I) { - unsigned ArgNum = *I; - - if (ArgNum == InvalidArgIndex) { - // Check if any of the arguments is tainted, but skip the - // destination arguments. - for (unsigned int i = 0; i < CE->getNumArgs(); ++i) { - if (isDestinationArgument(i)) - continue; - if ((IsTainted = isTaintedOrPointsToTainted(CE->getArg(i), State, C))) - break; - } - break; - } - - if (CE->getNumArgs() < (ArgNum + 1)) + for (unsigned ArgNum : SrcArgs) { + if (ArgNum >= CE->getNumArgs()) return State; if ((IsTainted = isTaintedOrPointsToTainted(CE->getArg(ArgNum), State, C))) break; } + + // Check for taint in variadic arguments. + if (!IsTainted && VariadicType::Src == VarType) { + // Check if any of the arguments is tainted + for (unsigned int i = VariadicIndex; i < CE->getNumArgs(); ++i) { + if ((IsTainted = isTaintedOrPointsToTainted(CE->getArg(i), State, C))) + break; + } + } + if (!IsTainted) return State; // Mark the arguments which should be tainted after the function returns. - for (ArgVector::const_iterator I = DstArgs.begin(), E = DstArgs.end(); I != E; - ++I) { - unsigned ArgNum = *I; - - // Should we mark all arguments as tainted? - if (ArgNum == InvalidArgIndex) { - // For all pointer and references that were passed in: - // If they are not pointing to const data, mark data as tainted. - // TODO: So far we are just going one level down; ideally we'd need to - // recurse here. - for (unsigned int i = 0; i < CE->getNumArgs(); ++i) { - const Expr *Arg = CE->getArg(i); - // Process pointer argument. - const Type *ArgTy = Arg->getType().getTypePtr(); - QualType PType = ArgTy->getPointeeType(); - if ((!PType.isNull() && !PType.isConstQualified()) || - (ArgTy->isReferenceType() && !Arg->getType().isConstQualified())) - State = State->add(i); - } - continue; - } - + for (unsigned ArgNum : DstArgs) { // Should mark the return value? if (ArgNum == ReturnValueIndex) { State = State->add(ReturnValueIndex); @@ -517,6 +491,23 @@ State = State->add(ArgNum); } + // Mark all variadic arguments tainted if present. + if (VariadicType::Dst == VarType) { + // For all pointer and references that were passed in: + // If they are not pointing to const data, mark data as tainted. + // TODO: So far we are just going one level down; ideally we'd need to + // recurse here. + for (unsigned int i = VariadicIndex; i < CE->getNumArgs(); ++i) { + const Expr *Arg = CE->getArg(i); + // Process pointer argument. + const Type *ArgTy = Arg->getType().getTypePtr(); + QualType PType = ArgTy->getPointeeType(); + if ((!PType.isNull() && !PType.isConstQualified()) || + (ArgTy->isReferenceType() && !Arg->getType().isConstQualified())) + State = State->add(i); + } + } + return State; } @@ -602,14 +593,14 @@ // This region corresponds to a declaration, find out if it's a global/extern // variable named stdin with the proper type. - if (const VarDecl *D = dyn_cast_or_null(DeclReg->getDecl())) { + if (const auto *D = dyn_cast_or_null(DeclReg->getDecl())) { D = D->getCanonicalDecl(); - if ((D->getName().find("stdin") != StringRef::npos) && D->isExternC()) - if (const PointerType *PtrTy = - dyn_cast(D->getType().getTypePtr())) - if (PtrTy->getPointeeType().getCanonicalType() == - C.getASTContext().getFILEType().getCanonicalType()) - return true; + if ((D->getName().find("stdin") != StringRef::npos) && D->isExternC()) { + const auto *PtrTy = dyn_cast(D->getType().getTypePtr()); + if (PtrTy && PtrTy->getPointeeType().getCanonicalType() == + C.getASTContext().getFILEType().getCanonicalType()) + return true; + } } return false; }