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+//== 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/ADT/StringRef.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 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)};
+ }
+
+ /// 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;
+
+ bool isTaintReporterCheckerEnabled = false;
+ std::optional<BugType> BT;
+
+private:
+ bool checkUncontrolledFormatString(const CallEvent &Call,
+ CheckerContext &C) const;
+
+ void taintUnsafeSocketProtocol(const CallEvent &Call,
+ CheckerContext &C) const;
+
+ /// The taint rules are initalized with the help of a CheckerContext to
+ /// access user-provided configuration.
+ void initTaintRules(CheckerContext &C) const;
+
+ // TODO: The two separate `CallDescriptionMap`s were introduced when
+ // `CallDescription` was unable to restrict matches to the global namespace
+ // only. This limitation no longer exists, so the following two maps should
+ // be unified.
+ 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(CDM::Unspecified, 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;
+
+ RulesConstructionTy GlobalCRules{
+ // Sources
+ {{CDM::CLibrary, {"fdopen"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"fopen"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"freopen"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getch"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getchar"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getchar_unlocked"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"gets"}}, TR::Source({{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"gets_s"}}, TR::Source({{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"scanf"}}, TR::Source({{}, 1})},
+ {{CDM::CLibrary, {"scanf_s"}}, TR::Source({{}, 1})},
+ {{CDM::CLibrary, {"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.
+ {{CDM::CLibrary, {"_IO_getc"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getcwd"}}, TR::Source({{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getwd"}}, TR::Source({{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"readlink"}}, TR::Source({{1, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"readlinkat"}}, TR::Source({{2, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"get_current_dir_name"}},
+ TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"gethostname"}}, TR::Source({{0}})},
+ {{CDM::CLibrary, {"getnameinfo"}}, TR::Source({{2, 4}})},
+ {{CDM::CLibrary, {"getseuserbyname"}}, TR::Source({{1, 2}})},
+ {{CDM::CLibrary, {"getgroups"}}, TR::Source({{1, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getlogin"}}, TR::Source({{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getlogin_r"}}, TR::Source({{0}})},
+
+ // Props
+ {{CDM::CLibrary, {"accept"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"atoi"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"atol"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"atoll"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"fgetc"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"fgetln"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"fgets"}},
+ TR::Prop({{2}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"fgetws"}},
+ TR::Prop({{2}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"fscanf"}}, TR::Prop({{0}}, {{}, 2})},
+ {{CDM::CLibrary, {"fscanf_s"}}, TR::Prop({{0}}, {{}, 2})},
+ {{CDM::CLibrary, {"sscanf"}}, TR::Prop({{0}}, {{}, 2})},
+ {{CDM::CLibrary, {"sscanf_s"}}, TR::Prop({{0}}, {{}, 2})},
+
+ {{CDM::CLibrary, {"getc"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getc_unlocked"}},
+ TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"getdelim"}}, TR::Prop({{3}}, {{0}})},
+ // TODO: this intends to match the C function `getline()`, but the call
+ // description also matches the C++ function `std::getline()`; it should
+ // be ruled out by some additional logic.
+ {{CDM::CLibrary, {"getline"}}, TR::Prop({{2}}, {{0}})},
+ {{CDM::CLibrary, {"getw"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"pread"}},
+ TR::Prop({{0, 1, 2, 3}}, {{1, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"read"}},
+ TR::Prop({{0, 2}}, {{1, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"fread"}},
+ TR::Prop({{3}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"recv"}},
+ TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"recvfrom"}},
+ TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"ttyname"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"ttyname_r"}},
+ TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"basename"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"dirname"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"fnmatch"}}, TR::Prop({{1}}, {{ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"mbtowc"}}, TR::Prop({{1}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"wctomb"}}, TR::Prop({{1}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"wcwidth"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"memcmp"}},
+ TR::Prop({{0, 1, 2}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"memcpy"}},
+ TR::Prop({{1, 2}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"memmove"}},
+ TR::Prop({{1, 2}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"bcopy"}}, TR::Prop({{0, 2}}, {{1}})},
+
+ // Note: "memmem" and its variants search for a byte sequence ("needle")
+ // in a larger area ("haystack"). Currently we only propagate taint from
+ // the haystack to the result, but in theory tampering with the needle
+ // could also produce incorrect results.
+ {{CDM::CLibrary, {"memmem"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strstr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strcasestr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+
+ // Analogously, the following functions search for a byte within a buffer
+ // and we only propagate taint from the buffer to the result.
+ {{CDM::CLibraryMaybeHardened, {"memchr"}},
+ TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"memrchr"}},
+ TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"rawmemchr"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strchr"}},
+ TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strrchr"}},
+ TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strchrnul"}},
+ TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"index"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"rindex"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+
+ // FIXME: In case of arrays, only the first element of the array gets
+ // tainted.
+ {{CDM::CLibrary, {"qsort"}}, TR::Prop({{0}}, {{0}})},
+ {{CDM::CLibrary, {"qsort_r"}}, TR::Prop({{0}}, {{0}})},
+
+ {{CDM::CLibrary, {"strcmp"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strcasecmp"}},
+ TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strncmp"}},
+ TR::Prop({{0, 1, 2}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strncasecmp"}},
+ TR::Prop({{0, 1, 2}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strspn"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strcspn"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strpbrk"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"strndup"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strndupa"}}, TR::Prop({{0, 1}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strdup"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strdupa"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"wcsdup"}}, 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
+
+ {{CDM::CLibrary, {"strtol"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strtoll"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strtoul"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+ {{CDM::CLibrary, {"strtoull"}}, TR::Prop({{0}}, {{1, ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"tolower"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"toupper"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+
+ {{CDM::CLibrary, {"isalnum"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isalpha"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isascii"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isblank"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"iscntrl"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isdigit"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isgraph"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"islower"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isprint"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"ispunct"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isspace"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isupper"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+ {{CDM::CLibrary, {"isxdigit"}}, TR::Prop({{0}}, {{ReturnValueIndex}})},
+
+ {{CDM::CLibraryMaybeHardened, {"strcpy"}},
+ TR::Prop({{1}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"stpcpy"}},
+ TR::Prop({{1}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strcat"}},
+ TR::Prop({{0, 1}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"wcsncat"}},
+ TR::Prop({{0, 1}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strncpy"}},
+ TR::Prop({{1, 2}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strncat"}},
+ TR::Prop({{0, 1, 2}}, {{0, ReturnValueIndex}})},
+ {{CDM::CLibraryMaybeHardened, {"strlcpy"}}, TR::Prop({{1, 2}}, {{0}})},
+ {{CDM::CLibraryMaybeHardened, {"strlcat"}}, TR::Prop({{0, 1, 2}}, {{0}})},
+
+ // Usually the matching mode `CDM::CLibraryMaybeHardened` is sufficient
+ // for unified handling of a function `FOO()` and its hardened variant
+ // `__FOO_chk()`, but in the "sprintf" family the extra parameters of the
+ // hardened variants are inserted into the middle of the parameter list,
+ // so that would not work in their case.
+ // int snprintf(char * str, size_t maxlen, const char * format, ...);
+ {{CDM::CLibrary, {"snprintf"}},
+ TR::Prop({{1, 2}, 3}, {{0, ReturnValueIndex}})},
+ // int sprintf(char * str, const char * format, ...);
+ {{CDM::CLibrary, {"sprintf"}},
+ TR::Prop({{1}, 2}, {{0, ReturnValueIndex}})},
+ // int __snprintf_chk(char * str, size_t maxlen, int flag, size_t strlen,
+ // const char * format, ...);
+ {{CDM::CLibrary, {"__snprintf_chk"}},
+ TR::Prop({{1, 4}, 5}, {{0, ReturnValueIndex}})},
+ // int __sprintf_chk(char * str, int flag, size_t strlen, const char *
+ // format, ...);
+ {{CDM::CLibrary, {"__sprintf_chk"}},
+ TR::Prop({{3}, 4}, {{0, ReturnValueIndex}})},
+
+ // Sinks
+ {{CDM::CLibrary, {"system"}}, TR::Sink({{0}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"popen"}}, TR::Sink({{0}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execl"}}, TR::Sink({{}, {0}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execle"}}, TR::Sink({{}, {0}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execlp"}}, TR::Sink({{}, {0}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execv"}}, TR::Sink({{0, 1}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execve"}},
+ TR::Sink({{0, 1, 2}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"fexecve"}},
+ TR::Sink({{0, 1, 2}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execvp"}}, TR::Sink({{0, 1}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"execvpe"}},
+ TR::Sink({{0, 1, 2}}, MsgSanitizeSystemArgs)},
+ {{CDM::CLibrary, {"dlopen"}}, TR::Sink({{0}}, MsgSanitizeSystemArgs)},
+
+ // malloc, calloc, alloca, realloc, memccpy
+ // are intentionally not marked as taint sinks because unconditional
+ // reporting for these functions generates many false positives.
+ // These taint sinks should be implemented in other checkers with more
+ // sophisticated sanitation heuristics.
+
+ {{CDM::CLibrary, {"setproctitle"}},
+ TR::Sink({{0}, 1}, MsgUncontrolledFormatString)},
+ {{CDM::CLibrary, {"setproctitle_fast"}},
+ TR::Sink({{0}, 1}, MsgUncontrolledFormatString)}};
+
+ if (TR::UntrustedEnv(C)) {
+ // void setproctitle_init(int argc, char *argv[], char *envp[])
+ // TODO: replace `MsgCustomSink` with a message that fits this situation.
+ GlobalCRules.push_back({{CDM::CLibrary, {"setproctitle_init"}},
+ TR::Sink({{1, 2}}, MsgCustomSink)});
+
+ // `getenv` returns taint only in untrusted environments.
+ GlobalCRules.push_back(
+ {{CDM::CLibrary, {"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);
+ if (!isTaintReporterCheckerEnabled)
+ return false;
+ std::optional<SVal> TaintedSVal =
+ getTaintedPointeeOrPointer(C.getState(), C.getSVal(E));
+
+ if (!TaintedSVal)
+ return false;
+
+ // Generate diagnostic.
+ assert(BT);
+ static CheckerProgramPointTag Tag(BT->getCheckerName(), Msg);
+ if (ExplodedNode *N = C.generateNonFatalErrorNode(C.getState(), &Tag)) {
+ 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() != "socket")
+ return;
+
+ SourceLocation DomLoc = Call.getArgExpr(0)->getExprLoc();
+ StringRef DomName = C.getMacroNameOrSpelling(DomLoc);
+ // Allow internal communication protocols.
+ bool SafeProtocol = DomName == "AF_SYSTEM" || DomName == "AF_LOCAL" ||
+ DomName == "AF_UNIX" || DomName == "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::registerTaintPropagationChecker(CheckerManager &Mgr) {
+ Mgr.registerChecker<GenericTaintChecker>();
+}
+
+bool ento::shouldRegisterTaintPropagationChecker(const CheckerManager &mgr) {
+ return true;
+}
+
+void ento::registerGenericTaintChecker(CheckerManager &Mgr) {
+ GenericTaintChecker *checker = Mgr.getChecker<GenericTaintChecker>();
+ checker->isTaintReporterCheckerEnabled = true;
+ checker->BT.emplace(Mgr.getCurrentCheckerName(), "Use of Untrusted Data",
+ categories::TaintedData);
+}
+
+bool ento::shouldRegisterGenericTaintChecker(const CheckerManager &mgr) {
+ return true;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-21 01:32:07 +0000