| //== GenericTaintChecker.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 defines the attack surface for generic taint propagation. |
| // |
| // The taint information produced by it might be useful to other checkers. For |
| // example, checkers should report errors which involve tainted data more |
| // aggressively, even if the involved symbols are under constrained. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "Yaml.h" |
| #include "clang/AST/Attr.h" |
| #include "clang/Basic/Builtins.h" |
| #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" |
| #include "clang/StaticAnalyzer/Checkers/Taint.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/CallDescription.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/Support/YAMLTraits.h" |
| |
| #include <limits> |
| #include <memory> |
| #include <optional> |
| #include <utility> |
| #include <vector> |
| |
| #define DEBUG_TYPE "taint-checker" |
| |
| using namespace clang; |
| using namespace ento; |
| using namespace taint; |
| |
| using llvm::ImmutableSet; |
| |
| namespace { |
| |
| class GenericTaintChecker; |
| |
| /// Check for CWE-134: Uncontrolled Format String. |
| constexpr llvm::StringLiteral MsgUncontrolledFormatString = |
| "Untrusted data is used as a format string " |
| "(CWE-134: Uncontrolled Format String)"; |
| |
| /// Check for: |
| /// CERT/STR02-C. "Sanitize data passed to complex subsystems" |
| /// CWE-78, "Failure to Sanitize Data into an OS Command" |
| constexpr llvm::StringLiteral MsgSanitizeSystemArgs = |
| "Untrusted data is passed to a system call " |
| "(CERT/STR02-C. Sanitize data passed to complex subsystems)"; |
| |
| /// Check if tainted data is used as a buffer size in strn.. functions, |
| /// and allocators. |
| constexpr llvm::StringLiteral 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)"; |
| |
| /// Check if tainted data is used as a custom sink's parameter. |
| constexpr llvm::StringLiteral MsgCustomSink = |
| "Untrusted data is passed to a user-defined sink"; |
| |
| using ArgIdxTy = int; |
| using ArgVecTy = llvm::SmallVector<ArgIdxTy, 2>; |
| |
| /// Denotes the return value. |
| constexpr ArgIdxTy ReturnValueIndex{-1}; |
| |
| static ArgIdxTy fromArgumentCount(unsigned Count) { |
| assert(Count <= |
| static_cast<std::size_t>(std::numeric_limits<ArgIdxTy>::max()) && |
| "ArgIdxTy is not large enough to represent the number of arguments."); |
| return Count; |
| } |
| |
| /// Check if the region the expression evaluates to is the standard input, |
| /// and thus, is tainted. |
| /// FIXME: Move this to Taint.cpp. |
| bool isStdin(SVal Val, const ASTContext &ACtx) { |
| // FIXME: What if Val is NonParamVarRegion? |
| |
| // The region should be symbolic, we do not know it's value. |
| const auto *SymReg = dyn_cast_or_null<SymbolicRegion>(Val.getAsRegion()); |
| if (!SymReg) |
| return false; |
| |
| // Get it's symbol and find the declaration region it's pointing to. |
| const auto *DeclReg = |
| dyn_cast_or_null<DeclRegion>(SymReg->getSymbol()->getOriginRegion()); |
| if (!DeclReg) |
| return false; |
| |
| // This region corresponds to a declaration, find out if it's a global/extern |
| // variable named stdin with the proper type. |
| if (const auto *D = dyn_cast_or_null<VarDecl>(DeclReg->getDecl())) { |
| D = D->getCanonicalDecl(); |
| if (D->getName() == "stdin" && D->hasExternalStorage() && D->isExternC()) { |
| const QualType FILETy = ACtx.getFILEType().getCanonicalType(); |
| const QualType Ty = D->getType().getCanonicalType(); |
| |
| if (Ty->isPointerType()) |
| return Ty->getPointeeType() == FILETy; |
| } |
| } |
| return false; |
| } |
| |
| SVal getPointeeOf(ProgramStateRef State, Loc LValue) { |
| const QualType ArgTy = LValue.getType(State->getStateManager().getContext()); |
| if (!ArgTy->isPointerType() || !ArgTy->getPointeeType()->isVoidType()) |
| return State->getSVal(LValue); |
| |
| // Do not dereference void pointers. Treat them as byte pointers instead. |
| // FIXME: we might want to consider more than just the first byte. |
| return State->getSVal(LValue, State->getStateManager().getContext().CharTy); |
| } |
| |
| /// Given a pointer/reference argument, return the value it refers to. |
| std::optional<SVal> getPointeeOf(ProgramStateRef State, SVal Arg) { |
| if (auto LValue = Arg.getAs<Loc>()) |
| return getPointeeOf(State, *LValue); |
| return std::nullopt; |
| } |
| |
| /// Given a pointer, return the SVal of its pointee or if it is tainted, |
| /// otherwise return the pointer's SVal if tainted. |
| /// Also considers stdin as a taint source. |
| std::optional<SVal> getTaintedPointeeOrPointer(ProgramStateRef State, |
| SVal Arg) { |
| if (auto Pointee = getPointeeOf(State, Arg)) |
| if (isTainted(State, *Pointee)) // FIXME: isTainted(...) ? Pointee : None; |
| return Pointee; |
| |
| if (isTainted(State, Arg)) |
| return Arg; |
| return std::nullopt; |
| } |
| |
| bool isTaintedOrPointsToTainted(ProgramStateRef State, SVal ExprSVal) { |
| return getTaintedPointeeOrPointer(State, ExprSVal).has_value(); |
| } |
| |
| /// Helps in printing taint diagnostics. |
| /// Marks the incoming parameters of a function interesting (to be printed) |
| /// when the return value, or the outgoing parameters are tainted. |
| const NoteTag *taintOriginTrackerTag(CheckerContext &C, |
| std::vector<SymbolRef> TaintedSymbols, |
| std::vector<ArgIdxTy> TaintedArgs, |
| const LocationContext *CallLocation) { |
| return C.getNoteTag([TaintedSymbols = std::move(TaintedSymbols), |
| TaintedArgs = std::move(TaintedArgs), CallLocation]( |
| PathSensitiveBugReport &BR) -> std::string { |
| SmallString<256> Msg; |
| // We give diagnostics only for taint related reports |
| if (!BR.isInteresting(CallLocation) || |
| BR.getBugType().getCategory() != categories::TaintedData) { |
| return ""; |
| } |
| if (TaintedSymbols.empty()) |
| return "Taint originated here"; |
| |
| for (auto Sym : TaintedSymbols) { |
| BR.markInteresting(Sym); |
| } |
| LLVM_DEBUG(for (auto Arg |
| : TaintedArgs) { |
| llvm::dbgs() << "Taint Propagated from argument " << Arg + 1 << "\n"; |
| }); |
| return ""; |
| }); |
| } |
| |
| /// Helps in printing taint diagnostics. |
| /// Marks the function interesting (to be printed) |
| /// when the return value, or the outgoing parameters are tainted. |
| const NoteTag *taintPropagationExplainerTag( |
| CheckerContext &C, std::vector<SymbolRef> TaintedSymbols, |
| std::vector<ArgIdxTy> TaintedArgs, const LocationContext *CallLocation) { |
| assert(TaintedSymbols.size() == TaintedArgs.size()); |
| return C.getNoteTag([TaintedSymbols = std::move(TaintedSymbols), |
| TaintedArgs = std::move(TaintedArgs), CallLocation]( |
| PathSensitiveBugReport &BR) -> std::string { |
| SmallString<256> Msg; |
| llvm::raw_svector_ostream Out(Msg); |
| // We give diagnostics only for taint related reports |
| if (TaintedSymbols.empty() || |
| BR.getBugType().getCategory() != categories::TaintedData) { |
| return ""; |
| } |
| int nofTaintedArgs = 0; |
| for (auto [Idx, Sym] : llvm::enumerate(TaintedSymbols)) { |
| if (BR.isInteresting(Sym)) { |
| BR.markInteresting(CallLocation); |
| if (TaintedArgs[Idx] != ReturnValueIndex) { |
| LLVM_DEBUG(llvm::dbgs() << "Taint Propagated to argument " |
| << TaintedArgs[Idx] + 1 << "\n"); |
| if (nofTaintedArgs == 0) |
| Out << "Taint propagated to the "; |
| else |
| Out << ", "; |
| Out << TaintedArgs[Idx] + 1 |
| << llvm::getOrdinalSuffix(TaintedArgs[Idx] + 1) << " argument"; |
| nofTaintedArgs++; |
| } else { |
| LLVM_DEBUG(llvm::dbgs() << "Taint Propagated to return value.\n"); |
| Out << "Taint propagated to the return value"; |
| } |
| } |
| } |
| return std::string(Out.str()); |
| }); |
| } |
| |
| /// ArgSet is used to describe arguments relevant for taint detection or |
| /// taint application. A discrete set of argument indexes and a variadic |
| /// argument list signified by a starting index are supported. |
| class ArgSet { |
| public: |
| ArgSet() = default; |
| ArgSet(ArgVecTy &&DiscreteArgs, |
| std::optional<ArgIdxTy> VariadicIndex = std::nullopt) |
| : DiscreteArgs(std::move(DiscreteArgs)), |
| VariadicIndex(std::move(VariadicIndex)) {} |
| |
| bool contains(ArgIdxTy ArgIdx) const { |
| if (llvm::is_contained(DiscreteArgs, ArgIdx)) |
| return true; |
| |
| return VariadicIndex && ArgIdx >= *VariadicIndex; |
| } |
| |
| bool isEmpty() const { return DiscreteArgs.empty() && !VariadicIndex; } |
| |
| private: |
| ArgVecTy DiscreteArgs; |
| std::optional<ArgIdxTy> VariadicIndex; |
| }; |
| |
| /// A struct used to specify taint propagation rules for a function. |
| /// |
| /// If any of the possible taint source arguments is tainted, all of the |
| /// destination arguments should also be tainted. If ReturnValueIndex is added |
| /// to the dst list, the return value will be tainted. |
| class GenericTaintRule { |
| /// Arguments which are taints sinks and should be checked, and a report |
| /// should be emitted if taint reaches these. |
| ArgSet SinkArgs; |
| /// Arguments which should be sanitized on function return. |
| ArgSet FilterArgs; |
| /// Arguments which can participate in taint propagation. If any of the |
| /// arguments in PropSrcArgs is tainted, all arguments in PropDstArgs should |
| /// be tainted. |
| ArgSet PropSrcArgs; |
| ArgSet PropDstArgs; |
| |
| /// A message that explains why the call is sensitive to taint. |
| std::optional<StringRef> SinkMsg; |
| |
| GenericTaintRule() = default; |
| |
| GenericTaintRule(ArgSet &&Sink, ArgSet &&Filter, ArgSet &&Src, ArgSet &&Dst, |
| std::optional<StringRef> SinkMsg = std::nullopt) |
| : SinkArgs(std::move(Sink)), FilterArgs(std::move(Filter)), |
| PropSrcArgs(std::move(Src)), PropDstArgs(std::move(Dst)), |
| SinkMsg(SinkMsg) {} |
| |
| public: |
| /// Make a rule that reports a warning if taint reaches any of \p FilterArgs |
| /// arguments. |
| static GenericTaintRule Sink(ArgSet &&SinkArgs, |
| std::optional<StringRef> Msg = std::nullopt) { |
| return {std::move(SinkArgs), {}, {}, {}, Msg}; |
| } |
| |
| /// Make a rule that sanitizes all FilterArgs arguments. |
| static GenericTaintRule Filter(ArgSet &&FilterArgs) { |
| return {{}, std::move(FilterArgs), {}, {}}; |
| } |
| |
| /// Make a rule that unconditionally taints all Args. |
| /// If Func is provided, it must also return true for taint to propagate. |
| static GenericTaintRule Source(ArgSet &&SourceArgs) { |
| return {{}, {}, {}, std::move(SourceArgs)}; |
| } |
| |
| /// Make a rule that taints all PropDstArgs if any of PropSrcArgs is tainted. |
| static GenericTaintRule Prop(ArgSet &&SrcArgs, ArgSet &&DstArgs) { |
| return {{}, {}, std::move(SrcArgs), std::move(DstArgs)}; |
| } |
| |
| /// Make a rule that taints all PropDstArgs if any of PropSrcArgs is tainted. |
| static GenericTaintRule |
| SinkProp(ArgSet &&SinkArgs, ArgSet &&SrcArgs, ArgSet &&DstArgs, |
| std::optional<StringRef> Msg = std::nullopt) { |
| return { |
| std::move(SinkArgs), {}, std::move(SrcArgs), std::move(DstArgs), Msg}; |
| } |
| |
| /// Process a function which could either be a taint source, a taint sink, a |
| /// taint filter or a taint propagator. |
| void process(const GenericTaintChecker &Checker, const CallEvent &Call, |
| CheckerContext &C) const; |
| |
| /// Handles the resolution of indexes of type ArgIdxTy to Expr*-s. |
| static const Expr *GetArgExpr(ArgIdxTy ArgIdx, const CallEvent &Call) { |
| return ArgIdx == ReturnValueIndex ? Call.getOriginExpr() |
| : Call.getArgExpr(ArgIdx); |
| }; |
| |
| /// Functions for custom taintedness propagation. |
| static bool UntrustedEnv(CheckerContext &C); |
| }; |
| |
| using RuleLookupTy = CallDescriptionMap<GenericTaintRule>; |
| |
| /// Used to parse the configuration file. |
| struct TaintConfiguration { |
| using NameScopeArgs = std::tuple<std::string, std::string, ArgVecTy>; |
| enum class VariadicType { None, Src, Dst }; |
| |
| struct Common { |
| std::string Name; |
| std::string Scope; |
| }; |
| |
| struct Sink : Common { |
| ArgVecTy SinkArgs; |
| }; |
| |
| struct Filter : Common { |
| ArgVecTy FilterArgs; |
| }; |
| |
| struct Propagation : Common { |
| ArgVecTy SrcArgs; |
| ArgVecTy DstArgs; |
| VariadicType VarType; |
| ArgIdxTy VarIndex; |
| }; |
| |
| std::vector<Propagation> Propagations; |
| std::vector<Filter> Filters; |
| std::vector<Sink> Sinks; |
| |
| TaintConfiguration() = default; |
| TaintConfiguration(const TaintConfiguration &) = default; |
| TaintConfiguration(TaintConfiguration &&) = default; |
| TaintConfiguration &operator=(const TaintConfiguration &) = default; |
| TaintConfiguration &operator=(TaintConfiguration &&) = default; |
| }; |
| |
| struct GenericTaintRuleParser { |
| GenericTaintRuleParser(CheckerManager &Mgr) : Mgr(Mgr) {} |
| /// Container type used to gather call identification objects grouped into |
| /// pairs with their corresponding taint rules. It is temporary as it is used |
| /// to finally initialize RuleLookupTy, which is considered to be immutable. |
| using RulesContTy = std::vector<std::pair<CallDescription, GenericTaintRule>>; |
| RulesContTy parseConfiguration(const std::string &Option, |
| TaintConfiguration &&Config) const; |
| |
| private: |
| using NamePartsTy = llvm::SmallVector<StringRef, 2>; |
| |
| /// Validate part of the configuration, which contains a list of argument |
| /// indexes. |
| void validateArgVector(const std::string &Option, const ArgVecTy &Args) const; |
| |
| template <typename Config> static NamePartsTy parseNameParts(const Config &C); |
| |
| // Takes the config and creates a CallDescription for it and associates a Rule |
| // with that. |
| template <typename Config> |
| static void consumeRulesFromConfig(const Config &C, GenericTaintRule &&Rule, |
| RulesContTy &Rules); |
| |
| void parseConfig(const std::string &Option, TaintConfiguration::Sink &&P, |
| RulesContTy &Rules) const; |
| void parseConfig(const std::string &Option, TaintConfiguration::Filter &&P, |
| RulesContTy &Rules) const; |
| void parseConfig(const std::string &Option, |
| TaintConfiguration::Propagation &&P, |
| RulesContTy &Rules) const; |
| |
| CheckerManager &Mgr; |
| }; |
| |
| class GenericTaintChecker : public Checker<check::PreCall, check::PostCall> { |
| public: |
| void checkPreCall(const CallEvent &Call, CheckerContext &C) const; |
| void checkPostCall(const CallEvent &Call, CheckerContext &C) const; |
| |
| void printState(raw_ostream &Out, ProgramStateRef State, const char *NL, |
| const char *Sep) const override; |
| |
| /// Generate a report if the expression is tainted or points to tainted data. |
| bool generateReportIfTainted(const Expr *E, StringRef Msg, |
| CheckerContext &C) const; |
| |
| private: |
| const BugType BT{this, "Use of Untrusted Data", categories::TaintedData}; |
| |
| bool checkUncontrolledFormatString(const CallEvent &Call, |
| CheckerContext &C) const; |
| |
| void taintUnsafeSocketProtocol(const CallEvent &Call, |
| CheckerContext &C) const; |
| |
| /// Default taint rules are initalized with the help of a CheckerContext to |
| /// access the names of built-in functions like memcpy. |
| void initTaintRules(CheckerContext &C) const; |
| |
| /// CallDescription currently cannot restrict matches to the global namespace |
| /// only, which is why multiple CallDescriptionMaps are used, as we want to |
| /// disambiguate global C functions from functions inside user-defined |
| /// namespaces. |
| // TODO: Remove separation to simplify matching logic once CallDescriptions |
| // are more expressive. |
| |
| mutable std::optional<RuleLookupTy> StaticTaintRules; |
| mutable std::optional<RuleLookupTy> DynamicTaintRules; |
| }; |
| } // end of anonymous namespace |
| |
| /// YAML serialization mapping. |
| LLVM_YAML_IS_SEQUENCE_VECTOR(TaintConfiguration::Sink) |
| LLVM_YAML_IS_SEQUENCE_VECTOR(TaintConfiguration::Filter) |
| LLVM_YAML_IS_SEQUENCE_VECTOR(TaintConfiguration::Propagation) |
| |
| namespace llvm { |
| namespace yaml { |
| template <> struct MappingTraits<TaintConfiguration> { |
| static void mapping(IO &IO, TaintConfiguration &Config) { |
| IO.mapOptional("Propagations", Config.Propagations); |
| IO.mapOptional("Filters", Config.Filters); |
| IO.mapOptional("Sinks", Config.Sinks); |
| } |
| }; |
| |
| template <> struct MappingTraits<TaintConfiguration::Sink> { |
| static void mapping(IO &IO, TaintConfiguration::Sink &Sink) { |
| IO.mapRequired("Name", Sink.Name); |
| IO.mapOptional("Scope", Sink.Scope); |
| IO.mapRequired("Args", Sink.SinkArgs); |
| } |
| }; |
| |
| template <> struct MappingTraits<TaintConfiguration::Filter> { |
| static void mapping(IO &IO, TaintConfiguration::Filter &Filter) { |
| IO.mapRequired("Name", Filter.Name); |
| IO.mapOptional("Scope", Filter.Scope); |
| IO.mapRequired("Args", Filter.FilterArgs); |
| } |
| }; |
| |
| template <> struct MappingTraits<TaintConfiguration::Propagation> { |
| static void mapping(IO &IO, TaintConfiguration::Propagation &Propagation) { |
| IO.mapRequired("Name", Propagation.Name); |
| IO.mapOptional("Scope", Propagation.Scope); |
| IO.mapOptional("SrcArgs", Propagation.SrcArgs); |
| IO.mapOptional("DstArgs", Propagation.DstArgs); |
| IO.mapOptional("VariadicType", Propagation.VarType); |
| IO.mapOptional("VariadicIndex", Propagation.VarIndex); |
| } |
| }; |
| |
| template <> struct ScalarEnumerationTraits<TaintConfiguration::VariadicType> { |
| static void enumeration(IO &IO, TaintConfiguration::VariadicType &Value) { |
| IO.enumCase(Value, "None", TaintConfiguration::VariadicType::None); |
| IO.enumCase(Value, "Src", TaintConfiguration::VariadicType::Src); |
| IO.enumCase(Value, "Dst", TaintConfiguration::VariadicType::Dst); |
| } |
| }; |
| } // namespace yaml |
| } // namespace llvm |
| |
| /// A set which is used to pass information from call pre-visit instruction |
| /// to the call post-visit. The values are signed integers, which are either |
| /// ReturnValueIndex, or indexes of the pointer/reference argument, which |
| /// points to data, which should be tainted on return. |
| REGISTER_MAP_WITH_PROGRAMSTATE(TaintArgsOnPostVisit, const LocationContext *, |
| ImmutableSet<ArgIdxTy>) |
| REGISTER_SET_FACTORY_WITH_PROGRAMSTATE(ArgIdxFactory, ArgIdxTy) |
| |
| void GenericTaintRuleParser::validateArgVector(const std::string &Option, |
| const ArgVecTy &Args) const { |
| for (ArgIdxTy Arg : Args) { |
| if (Arg < ReturnValueIndex) { |
| Mgr.reportInvalidCheckerOptionValue( |
| Mgr.getChecker<GenericTaintChecker>(), Option, |
| "an argument number for propagation rules greater or equal to -1"); |
| } |
| } |
| } |
| |
| template <typename Config> |
| GenericTaintRuleParser::NamePartsTy |
| GenericTaintRuleParser::parseNameParts(const Config &C) { |
| NamePartsTy NameParts; |
| if (!C.Scope.empty()) { |
| // If the Scope argument contains multiple "::" parts, those are considered |
| // namespace identifiers. |
| StringRef{C.Scope}.split(NameParts, "::", /*MaxSplit*/ -1, |
| /*KeepEmpty*/ false); |
| } |
| NameParts.emplace_back(C.Name); |
| return NameParts; |
| } |
| |
| template <typename Config> |
| void GenericTaintRuleParser::consumeRulesFromConfig(const Config &C, |
| GenericTaintRule &&Rule, |
| RulesContTy &Rules) { |
| NamePartsTy NameParts = parseNameParts(C); |
| Rules.emplace_back(CallDescription(NameParts), std::move(Rule)); |
| } |
| |
| void GenericTaintRuleParser::parseConfig(const std::string &Option, |
| TaintConfiguration::Sink &&S, |
| RulesContTy &Rules) const { |
| validateArgVector(Option, S.SinkArgs); |
| consumeRulesFromConfig(S, GenericTaintRule::Sink(std::move(S.SinkArgs)), |
| Rules); |
| } |
| |
| void GenericTaintRuleParser::parseConfig(const std::string &Option, |
| TaintConfiguration::Filter &&S, |
| RulesContTy &Rules) const { |
| validateArgVector(Option, S.FilterArgs); |
| consumeRulesFromConfig(S, GenericTaintRule::Filter(std::move(S.FilterArgs)), |
| Rules); |
| } |
| |
| void GenericTaintRuleParser::parseConfig(const std::string &Option, |
| TaintConfiguration::Propagation &&P, |
| RulesContTy &Rules) const { |
| validateArgVector(Option, P.SrcArgs); |
| validateArgVector(Option, P.DstArgs); |
| bool IsSrcVariadic = P.VarType == TaintConfiguration::VariadicType::Src; |
| bool IsDstVariadic = P.VarType == TaintConfiguration::VariadicType::Dst; |
| std::optional<ArgIdxTy> JustVarIndex = P.VarIndex; |
| |
| ArgSet SrcDesc(std::move(P.SrcArgs), |
| IsSrcVariadic ? JustVarIndex : std::nullopt); |
| ArgSet DstDesc(std::move(P.DstArgs), |
| IsDstVariadic ? JustVarIndex : std::nullopt); |
| |
| consumeRulesFromConfig( |
| P, GenericTaintRule::Prop(std::move(SrcDesc), std::move(DstDesc)), Rules); |
| } |
| |
| GenericTaintRuleParser::RulesContTy |
| GenericTaintRuleParser::parseConfiguration(const std::string &Option, |
| TaintConfiguration &&Config) const { |
| |
| RulesContTy Rules; |
| |
| for (auto &F : Config.Filters) |
| parseConfig(Option, std::move(F), Rules); |
| |
| for (auto &S : Config.Sinks) |
| parseConfig(Option, std::move(S), Rules); |
| |
| for (auto &P : Config.Propagations) |
| parseConfig(Option, std::move(P), Rules); |
| |
| return Rules; |
| } |
| |
| void GenericTaintChecker::initTaintRules(CheckerContext &C) const { |
| // Check for exact name match for functions without builtin substitutes. |
| // Use qualified name, because these are C functions without namespace. |
| |
| if (StaticTaintRules || DynamicTaintRules) |
| return; |
| |
| using RulesConstructionTy = |
| std::vector<std::pair<CallDescription, GenericTaintRule>>; |
| using TR = GenericTaintRule; |
| |
| const Builtin::Context &BI = C.getASTContext().BuiltinInfo; |
| |
| RulesConstructionTy GlobalCRules{ |
| // Sources |
| {{{"fdopen"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"fopen"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"freopen"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"getch"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"getchar"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"getchar_unlocked"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"gets"}}, TR::Source({{0}, ReturnValueIndex})}, |
| {{{"gets_s"}}, TR::Source({{0}, ReturnValueIndex})}, |
| {{{"scanf"}}, TR::Source({{}, 1})}, |
| {{{"scanf_s"}}, TR::Source({{}, {1}})}, |
| {{{"wgetch"}}, TR::Source({{}, ReturnValueIndex})}, |
| // Sometimes the line between taint sources and propagators is blurry. |
| // _IO_getc is choosen to be a source, but could also be a propagator. |
| // This way it is simpler, as modeling it as a propagator would require |
| // to model the possible sources of _IO_FILE * values, which the _IO_getc |
| // function takes as parameters. |
| {{{"_IO_getc"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"getcwd"}}, TR::Source({{0, ReturnValueIndex}})}, |
| {{{"getwd"}}, TR::Source({{0, ReturnValueIndex}})}, |
| {{{"readlink"}}, TR::Source({{1, ReturnValueIndex}})}, |
| {{{"readlinkat"}}, TR::Source({{2, ReturnValueIndex}})}, |
| {{{"get_current_dir_name"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"gethostname"}}, TR::Source({{0}})}, |
| {{{"getnameinfo"}}, TR::Source({{2, 4}})}, |
| {{{"getseuserbyname"}}, TR::Source({{1, 2}})}, |
| {{{"getgroups"}}, TR::Source({{1, ReturnValueIndex}})}, |
| {{{"getlogin"}}, TR::Source({{ReturnValueIndex}})}, |
| {{{"getlogin_r"}}, TR::Source({{0}})}, |
| |
| // Props |
| {{{"accept"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"atoi"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"atol"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"atoll"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"fgetc"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"fgetln"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"fgets"}}, TR::Prop({{2}}, {{0, ReturnValueIndex}})}, |
| {{{"fgetws"}}, TR::Prop({{2}}, {{0, ReturnValueIndex}})}, |
| {{{"fscanf"}}, TR::Prop({{0}}, {{}, 2})}, |
| {{{"fscanf_s"}}, TR::Prop({{0}}, {{}, {2}})}, |
| {{{"sscanf"}}, TR::Prop({{0}}, {{}, 2})}, |
| |
| {{{"getc"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"getc_unlocked"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"getdelim"}}, TR::Prop({{3}}, {{0}})}, |
| {{{"getline"}}, TR::Prop({{2}}, {{0}})}, |
| {{{"getw"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"pread"}}, TR::Prop({{0, 1, 2, 3}}, {{1, ReturnValueIndex}})}, |
| {{{"read"}}, TR::Prop({{0, 2}}, {{1, ReturnValueIndex}})}, |
| {{{"strchr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"strrchr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"tolower"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"toupper"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"fread"}}, TR::Prop({{3}}, {{0, ReturnValueIndex}})}, |
| {{{"recv"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| {{{"recvfrom"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| |
| {{{"ttyname"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"ttyname_r"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| |
| {{{"basename"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"dirname"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"fnmatch"}}, TR::Prop({{1}}, {{ReturnValueIndex}})}, |
| {{{"memchr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"memrchr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"rawmemchr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| {{{"mbtowc"}}, TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{{"wctomb"}}, TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{{"wcwidth"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| {{{"memcmp"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})}, |
| {{{"memcpy"}}, TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{{"memmove"}}, TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| // If memmem was called with a tainted needle and the search was |
| // successful, that would mean that the value pointed by the return value |
| // has the same content as the needle. If we choose to go by the policy of |
| // content equivalence implies taintedness equivalence, that would mean |
| // haystack should be considered a propagation source argument. |
| {{{"memmem"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| // The comment for memmem above also applies to strstr. |
| {{{"strstr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"strcasestr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| {{{"strchrnul"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| {{{"index"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"rindex"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| // FIXME: In case of arrays, only the first element of the array gets |
| // tainted. |
| {{{"qsort"}}, TR::Prop({{0}}, {{0}})}, |
| {{{"qsort_r"}}, TR::Prop({{0}}, {{0}})}, |
| |
| {{{"strcmp"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})}, |
| {{{"strcasecmp"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})}, |
| {{{"strncmp"}}, TR::Prop({{0, 1, 2}}, {{ReturnValueIndex}})}, |
| {{{"strncasecmp"}}, TR::Prop({{0, 1, 2}}, {{ReturnValueIndex}})}, |
| {{{"strspn"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})}, |
| {{{"strcspn"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})}, |
| {{{"strpbrk"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"strndup"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"strndupa"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| // strlen, wcslen, strnlen and alike intentionally don't propagate taint. |
| // See the details here: https://github.com/llvm/llvm-project/pull/66086 |
| |
| {{{"strtol"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| {{{"strtoll"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| {{{"strtoul"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| {{{"strtoull"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})}, |
| |
| {{{"isalnum"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isalpha"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isascii"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isblank"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"iscntrl"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isdigit"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isgraph"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"islower"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isprint"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"ispunct"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isspace"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isupper"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{{"isxdigit"}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| {{CDM::CLibraryMaybeHardened, {BI.getName(Builtin::BIstrncat)}}, |
| TR::Prop({{1, 2}}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibraryMaybeHardened, {BI.getName(Builtin::BIstrlcpy)}}, |
| TR::Prop({{1, 2}}, {{0}})}, |
| {{CDM::CLibraryMaybeHardened, {BI.getName(Builtin::BIstrlcat)}}, |
| TR::Prop({{1, 2}}, {{0}})}, |
| {{CDM::CLibraryMaybeHardened, {{"snprintf"}}}, |
| TR::Prop({{1}, 3}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibraryMaybeHardened, {{"sprintf"}}}, |
| TR::Prop({{1}, 2}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibraryMaybeHardened, {{"strcpy"}}}, |
| TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibraryMaybeHardened, {{"stpcpy"}}}, |
| TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibraryMaybeHardened, {{"strcat"}}}, |
| TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibraryMaybeHardened, {{"wcsncat"}}}, |
| TR::Prop({{1}}, {{0, ReturnValueIndex}})}, |
| {{CDM::CLibrary, {{"strdup"}}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{CDM::CLibrary, {{"strdupa"}}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| {{CDM::CLibrary, {{"wcsdup"}}}, TR::Prop({{0}}, {{ReturnValueIndex}})}, |
| |
| // Sinks |
| {{{"system"}}, TR::Sink({{0}}, MsgSanitizeSystemArgs)}, |
| {{{"popen"}}, TR::Sink({{0}}, MsgSanitizeSystemArgs)}, |
| {{{"execl"}}, TR::Sink({{}, {0}}, MsgSanitizeSystemArgs)}, |
| {{{"execle"}}, TR::Sink({{}, {0}}, MsgSanitizeSystemArgs)}, |
| {{{"execlp"}}, TR::Sink({{}, {0}}, MsgSanitizeSystemArgs)}, |
| {{{"execv"}}, TR::Sink({{0, 1}}, MsgSanitizeSystemArgs)}, |
| {{{"execve"}}, TR::Sink({{0, 1, 2}}, MsgSanitizeSystemArgs)}, |
| {{{"fexecve"}}, TR::Sink({{0, 1, 2}}, MsgSanitizeSystemArgs)}, |
| {{{"execvp"}}, TR::Sink({{0, 1}}, MsgSanitizeSystemArgs)}, |
| {{{"execvpe"}}, TR::Sink({{0, 1, 2}}, MsgSanitizeSystemArgs)}, |
| {{{"dlopen"}}, TR::Sink({{0}}, MsgSanitizeSystemArgs)}, |
| {{CDM::CLibrary, {{"malloc"}}}, TR::Sink({{0}}, MsgTaintedBufferSize)}, |
| {{CDM::CLibrary, {{"calloc"}}}, TR::Sink({{0}}, MsgTaintedBufferSize)}, |
| {{CDM::CLibrary, {{"alloca"}}}, TR::Sink({{0}}, MsgTaintedBufferSize)}, |
| {{CDM::CLibrary, {{"memccpy"}}}, TR::Sink({{3}}, MsgTaintedBufferSize)}, |
| {{CDM::CLibrary, {{"realloc"}}}, TR::Sink({{1}}, MsgTaintedBufferSize)}, |
| {{{{"setproctitle"}}}, TR::Sink({{0}, 1}, MsgUncontrolledFormatString)}, |
| {{{{"setproctitle_fast"}}}, |
| TR::Sink({{0}, 1}, MsgUncontrolledFormatString)}, |
| |
| // SinkProps |
| {{CDM::CLibraryMaybeHardened, BI.getName(Builtin::BImemcpy)}, |
| TR::SinkProp({{2}}, {{1, 2}}, {{0, ReturnValueIndex}}, |
| MsgTaintedBufferSize)}, |
| {{CDM::CLibraryMaybeHardened, {BI.getName(Builtin::BImemmove)}}, |
| TR::SinkProp({{2}}, {{1, 2}}, {{0, ReturnValueIndex}}, |
| MsgTaintedBufferSize)}, |
| {{CDM::CLibraryMaybeHardened, {BI.getName(Builtin::BIstrncpy)}}, |
| TR::SinkProp({{2}}, {{1, 2}}, {{0, ReturnValueIndex}}, |
| MsgTaintedBufferSize)}, |
| {{CDM::CLibrary, {BI.getName(Builtin::BIstrndup)}}, |
| TR::SinkProp({{1}}, {{0, 1}}, {{ReturnValueIndex}}, |
| MsgTaintedBufferSize)}, |
| {{CDM::CLibrary, {{"bcopy"}}}, |
| TR::SinkProp({{2}}, {{0, 2}}, {{1}}, MsgTaintedBufferSize)}}; |
| |
| // `getenv` returns taint only in untrusted environments. |
| if (TR::UntrustedEnv(C)) { |
| // void setproctitle_init(int argc, char *argv[], char *envp[]) |
| GlobalCRules.push_back( |
| {{{"setproctitle_init"}}, TR::Sink({{1, 2}}, MsgCustomSink)}); |
| GlobalCRules.push_back({{{"getenv"}}, TR::Source({{ReturnValueIndex}})}); |
| } |
| |
| StaticTaintRules.emplace(std::make_move_iterator(GlobalCRules.begin()), |
| std::make_move_iterator(GlobalCRules.end())); |
| |
| // User-provided taint configuration. |
| CheckerManager *Mgr = C.getAnalysisManager().getCheckerManager(); |
| assert(Mgr); |
| GenericTaintRuleParser ConfigParser{*Mgr}; |
| std::string Option{"Config"}; |
| StringRef ConfigFile = |
| Mgr->getAnalyzerOptions().getCheckerStringOption(this, Option); |
| std::optional<TaintConfiguration> Config = |
| getConfiguration<TaintConfiguration>(*Mgr, this, Option, ConfigFile); |
| if (!Config) { |
| // We don't have external taint config, no parsing required. |
| DynamicTaintRules = RuleLookupTy{}; |
| return; |
| } |
| |
| GenericTaintRuleParser::RulesContTy Rules{ |
| ConfigParser.parseConfiguration(Option, std::move(*Config))}; |
| |
| DynamicTaintRules.emplace(std::make_move_iterator(Rules.begin()), |
| std::make_move_iterator(Rules.end())); |
| } |
| |
| void GenericTaintChecker::checkPreCall(const CallEvent &Call, |
| CheckerContext &C) const { |
| initTaintRules(C); |
| |
| // FIXME: this should be much simpler. |
| if (const auto *Rule = |
| Call.isGlobalCFunction() ? StaticTaintRules->lookup(Call) : nullptr) |
| Rule->process(*this, Call, C); |
| else if (const auto *Rule = DynamicTaintRules->lookup(Call)) |
| Rule->process(*this, Call, C); |
| |
| // FIXME: These edge cases are to be eliminated from here eventually. |
| // |
| // Additional check that is not supported by CallDescription. |
| // TODO: Make CallDescription be able to match attributes such as printf-like |
| // arguments. |
| checkUncontrolledFormatString(Call, C); |
| |
| // TODO: Modeling sockets should be done in a specific checker. |
| // Socket is a source, which taints the return value. |
| taintUnsafeSocketProtocol(Call, C); |
| } |
| |
| void GenericTaintChecker::checkPostCall(const CallEvent &Call, |
| CheckerContext &C) const { |
| // Set the marked values as tainted. The return value only accessible from |
| // checkPostStmt. |
| ProgramStateRef State = C.getState(); |
| const StackFrameContext *CurrentFrame = C.getStackFrame(); |
| |
| // Depending on what was tainted at pre-visit, we determined a set of |
| // arguments which should be tainted after the function returns. These are |
| // stored in the state as TaintArgsOnPostVisit set. |
| TaintArgsOnPostVisitTy TaintArgsMap = State->get<TaintArgsOnPostVisit>(); |
| |
| const ImmutableSet<ArgIdxTy> *TaintArgs = TaintArgsMap.lookup(CurrentFrame); |
| if (!TaintArgs) |
| return; |
| assert(!TaintArgs->isEmpty()); |
| |
| LLVM_DEBUG(for (ArgIdxTy I |
| : *TaintArgs) { |
| llvm::dbgs() << "PostCall<"; |
| Call.dump(llvm::dbgs()); |
| llvm::dbgs() << "> actually wants to taint arg index: " << I << '\n'; |
| }); |
| |
| const NoteTag *InjectionTag = nullptr; |
| std::vector<SymbolRef> TaintedSymbols; |
| std::vector<ArgIdxTy> TaintedIndexes; |
| for (ArgIdxTy ArgNum : *TaintArgs) { |
| // Special handling for the tainted return value. |
| if (ArgNum == ReturnValueIndex) { |
| State = addTaint(State, Call.getReturnValue()); |
| std::vector<SymbolRef> TaintedSyms = |
| getTaintedSymbols(State, Call.getReturnValue()); |
| if (!TaintedSyms.empty()) { |
| TaintedSymbols.push_back(TaintedSyms[0]); |
| TaintedIndexes.push_back(ArgNum); |
| } |
| continue; |
| } |
| // The arguments are pointer arguments. The data they are pointing at is |
| // tainted after the call. |
| if (auto V = getPointeeOf(State, Call.getArgSVal(ArgNum))) { |
| State = addTaint(State, *V); |
| std::vector<SymbolRef> TaintedSyms = getTaintedSymbols(State, *V); |
| if (!TaintedSyms.empty()) { |
| TaintedSymbols.push_back(TaintedSyms[0]); |
| TaintedIndexes.push_back(ArgNum); |
| } |
| } |
| } |
| // Create a NoteTag callback, which prints to the user where the taintedness |
| // was propagated to. |
| InjectionTag = taintPropagationExplainerTag(C, TaintedSymbols, TaintedIndexes, |
| Call.getCalleeStackFrame(0)); |
| // Clear up the taint info from the state. |
| State = State->remove<TaintArgsOnPostVisit>(CurrentFrame); |
| C.addTransition(State, InjectionTag); |
| } |
| |
| void GenericTaintChecker::printState(raw_ostream &Out, ProgramStateRef State, |
| const char *NL, const char *Sep) const { |
| printTaint(State, Out, NL, Sep); |
| } |
| |
| void GenericTaintRule::process(const GenericTaintChecker &Checker, |
| const CallEvent &Call, CheckerContext &C) const { |
| ProgramStateRef State = C.getState(); |
| const ArgIdxTy CallNumArgs = fromArgumentCount(Call.getNumArgs()); |
| |
| /// Iterate every call argument, and get their corresponding Expr and SVal. |
| const auto ForEachCallArg = [&C, &Call, CallNumArgs](auto &&Fun) { |
| for (ArgIdxTy I = ReturnValueIndex; I < CallNumArgs; ++I) { |
| const Expr *E = GetArgExpr(I, Call); |
| Fun(I, E, C.getSVal(E)); |
| } |
| }; |
| |
| /// Check for taint sinks. |
| ForEachCallArg([this, &Checker, &C, &State](ArgIdxTy I, const Expr *E, SVal) { |
| // Add taintedness to stdin parameters |
| if (isStdin(C.getSVal(E), C.getASTContext())) { |
| State = addTaint(State, C.getSVal(E)); |
| } |
| if (SinkArgs.contains(I) && isTaintedOrPointsToTainted(State, C.getSVal(E))) |
| Checker.generateReportIfTainted(E, SinkMsg.value_or(MsgCustomSink), C); |
| }); |
| |
| /// Check for taint filters. |
| ForEachCallArg([this, &State](ArgIdxTy I, const Expr *E, SVal S) { |
| if (FilterArgs.contains(I)) { |
| State = removeTaint(State, S); |
| if (auto P = getPointeeOf(State, S)) |
| State = removeTaint(State, *P); |
| } |
| }); |
| |
| /// Check for taint propagation sources. |
| /// A rule will make the destination variables tainted if PropSrcArgs |
| /// is empty (taints the destination |
| /// arguments unconditionally), or if any of its signified |
| /// args are tainted in context of the current CallEvent. |
| bool IsMatching = PropSrcArgs.isEmpty(); |
| std::vector<SymbolRef> TaintedSymbols; |
| std::vector<ArgIdxTy> TaintedIndexes; |
| ForEachCallArg([this, &C, &IsMatching, &State, &TaintedSymbols, |
| &TaintedIndexes](ArgIdxTy I, const Expr *E, SVal) { |
| std::optional<SVal> TaintedSVal = |
| getTaintedPointeeOrPointer(State, C.getSVal(E)); |
| IsMatching = |
| IsMatching || (PropSrcArgs.contains(I) && TaintedSVal.has_value()); |
| |
| // We track back tainted arguments except for stdin |
| if (TaintedSVal && !isStdin(*TaintedSVal, C.getASTContext())) { |
| std::vector<SymbolRef> TaintedArgSyms = |
| getTaintedSymbols(State, *TaintedSVal); |
| if (!TaintedArgSyms.empty()) { |
| llvm::append_range(TaintedSymbols, TaintedArgSyms); |
| TaintedIndexes.push_back(I); |
| } |
| } |
| }); |
| |
| // Early return for propagation rules which dont match. |
| // Matching propagations, Sinks and Filters will pass this point. |
| if (!IsMatching) |
| return; |
| |
| const auto WouldEscape = [](SVal V, QualType Ty) -> bool { |
| if (!isa<Loc>(V)) |
| return false; |
| |
| const bool IsNonConstRef = Ty->isReferenceType() && !Ty.isConstQualified(); |
| const bool IsNonConstPtr = |
| Ty->isPointerType() && !Ty->getPointeeType().isConstQualified(); |
| |
| return IsNonConstRef || IsNonConstPtr; |
| }; |
| |
| /// Propagate taint where it is necessary. |
| auto &F = State->getStateManager().get_context<ArgIdxFactory>(); |
| ImmutableSet<ArgIdxTy> Result = F.getEmptySet(); |
| ForEachCallArg( |
| [&](ArgIdxTy I, const Expr *E, SVal V) { |
| if (PropDstArgs.contains(I)) { |
| LLVM_DEBUG(llvm::dbgs() << "PreCall<"; Call.dump(llvm::dbgs()); |
| llvm::dbgs() |
| << "> prepares tainting arg index: " << I << '\n';); |
| Result = F.add(Result, I); |
| } |
| |
| // Taint property gets lost if the variable is passed as a |
| // non-const pointer or reference to a function which is |
| // not inlined. For matching rules we want to preserve the taintedness. |
| // TODO: We should traverse all reachable memory regions via the |
| // escaping parameter. Instead of doing that we simply mark only the |
| // referred memory region as tainted. |
| if (WouldEscape(V, E->getType()) && getTaintedPointeeOrPointer(State, V)) { |
| LLVM_DEBUG(if (!Result.contains(I)) { |
| llvm::dbgs() << "PreCall<"; |
| Call.dump(llvm::dbgs()); |
| llvm::dbgs() << "> prepares tainting arg index: " << I << '\n'; |
| }); |
| Result = F.add(Result, I); |
| } |
| }); |
| |
| if (!Result.isEmpty()) |
| State = State->set<TaintArgsOnPostVisit>(C.getStackFrame(), Result); |
| const NoteTag *InjectionTag = taintOriginTrackerTag( |
| C, std::move(TaintedSymbols), std::move(TaintedIndexes), |
| Call.getCalleeStackFrame(0)); |
| C.addTransition(State, InjectionTag); |
| } |
| |
| bool GenericTaintRule::UntrustedEnv(CheckerContext &C) { |
| return !C.getAnalysisManager() |
| .getAnalyzerOptions() |
| .ShouldAssumeControlledEnvironment; |
| } |
| |
| bool GenericTaintChecker::generateReportIfTainted(const Expr *E, StringRef Msg, |
| CheckerContext &C) const { |
| assert(E); |
| std::optional<SVal> TaintedSVal = |
| getTaintedPointeeOrPointer(C.getState(), C.getSVal(E)); |
| |
| if (!TaintedSVal) |
| return false; |
| |
| // Generate diagnostic. |
| if (ExplodedNode *N = C.generateNonFatalErrorNode()) { |
| auto report = std::make_unique<PathSensitiveBugReport>(BT, Msg, N); |
| report->addRange(E->getSourceRange()); |
| for (auto TaintedSym : getTaintedSymbols(C.getState(), *TaintedSVal)) { |
| report->markInteresting(TaintedSym); |
| } |
| |
| C.emitReport(std::move(report)); |
| return true; |
| } |
| return false; |
| } |
| |
| /// TODO: remove checking for printf format attributes and socket whitelisting |
| /// from GenericTaintChecker, and that means the following functions: |
| /// getPrintfFormatArgumentNum, |
| /// GenericTaintChecker::checkUncontrolledFormatString, |
| /// GenericTaintChecker::taintUnsafeSocketProtocol |
| |
| static bool getPrintfFormatArgumentNum(const CallEvent &Call, |
| const CheckerContext &C, |
| ArgIdxTy &ArgNum) { |
| // Find if the function contains a format string argument. |
| // Handles: fprintf, printf, sprintf, snprintf, vfprintf, vprintf, vsprintf, |
| // vsnprintf, syslog, custom annotated functions. |
| const Decl *CallDecl = Call.getDecl(); |
| if (!CallDecl) |
| return false; |
| const FunctionDecl *FDecl = CallDecl->getAsFunction(); |
| if (!FDecl) |
| return false; |
| |
| const ArgIdxTy CallNumArgs = fromArgumentCount(Call.getNumArgs()); |
| |
| for (const auto *Format : FDecl->specific_attrs<FormatAttr>()) { |
| ArgNum = Format->getFormatIdx() - 1; |
| if ((Format->getType()->getName() == "printf") && CallNumArgs > ArgNum) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| bool GenericTaintChecker::checkUncontrolledFormatString( |
| const CallEvent &Call, CheckerContext &C) const { |
| // Check if the function contains a format string argument. |
| ArgIdxTy ArgNum = 0; |
| if (!getPrintfFormatArgumentNum(Call, C, ArgNum)) |
| return false; |
| |
| // If either the format string content or the pointer itself are tainted, |
| // warn. |
| return generateReportIfTainted(Call.getArgExpr(ArgNum), |
| MsgUncontrolledFormatString, C); |
| } |
| |
| void GenericTaintChecker::taintUnsafeSocketProtocol(const CallEvent &Call, |
| CheckerContext &C) const { |
| if (Call.getNumArgs() < 1) |
| return; |
| const IdentifierInfo *ID = Call.getCalleeIdentifier(); |
| if (!ID) |
| return; |
| if (!ID->getName().equals("socket")) |
| return; |
| |
| SourceLocation DomLoc = Call.getArgExpr(0)->getExprLoc(); |
| StringRef DomName = C.getMacroNameOrSpelling(DomLoc); |
| // Allow internal communication protocols. |
| bool SafeProtocol = DomName.equals("AF_SYSTEM") || |
| DomName.equals("AF_LOCAL") || DomName.equals("AF_UNIX") || |
| DomName.equals("AF_RESERVED_36"); |
| if (SafeProtocol) |
| return; |
| |
| ProgramStateRef State = C.getState(); |
| auto &F = State->getStateManager().get_context<ArgIdxFactory>(); |
| ImmutableSet<ArgIdxTy> Result = F.add(F.getEmptySet(), ReturnValueIndex); |
| State = State->set<TaintArgsOnPostVisit>(C.getStackFrame(), Result); |
| C.addTransition(State); |
| } |
| |
| /// Checker registration |
| void ento::registerGenericTaintChecker(CheckerManager &Mgr) { |
| Mgr.registerChecker<GenericTaintChecker>(); |
| } |
| |
| bool ento::shouldRegisterGenericTaintChecker(const CheckerManager &mgr) { |
| return true; |
| } |