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[analyzer] Add support for namespaces to GenericTaintChecker
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This patch introduces the namespaces for the configured functions and
also enables the use of the member functions.

I added an optional Scope field for every configured function. Functions
without Scope match for every function regardless of the namespace.
Functions with Scope will match if the full name of the function starts
with the Scope.
Multiple functions can exist with the same name.

Differential Revision: https://reviews.llvm.org/D70878
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@boga95
boga95 committed Dec 15, 2019
1 parent 0133dc3 commit 273e674
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Showing 3 changed files with 290 additions and 58 deletions.
181 changes: 123 additions & 58 deletions clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp
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Expand Up @@ -24,9 +24,10 @@
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/YAMLTraits.h"
#include <algorithm>
#include <limits>
#include <unordered_map>
#include <utility>

using namespace clang;
Expand Down Expand Up @@ -56,19 +57,20 @@ class GenericTaintChecker

/// Used to parse the configuration file.
struct TaintConfiguration {
using NameArgsPair = std::pair<std::string, ArgVector>;
using NameScopeArgs = std::tuple<std::string, std::string, ArgVector>;

struct Propagation {
std::string Name;
std::string Scope;
ArgVector SrcArgs;
SignedArgVector DstArgs;
VariadicType VarType;
unsigned VarIndex;
};

std::vector<Propagation> Propagations;
std::vector<NameArgsPair> Filters;
std::vector<NameArgsPair> Sinks;
std::vector<NameScopeArgs> Filters;
std::vector<NameScopeArgs> Sinks;

TaintConfiguration() = default;
TaintConfiguration(const TaintConfiguration &) = default;
Expand Down Expand Up @@ -97,18 +99,49 @@ class GenericTaintChecker
BT.reset(new BugType(this, "Use of Untrusted Data", "Untrusted Data"));
}

struct FunctionData {
FunctionData() = delete;
FunctionData(const FunctionData &) = default;
FunctionData(FunctionData &&) = default;
FunctionData &operator=(const FunctionData &) = delete;
FunctionData &operator=(FunctionData &&) = delete;

static Optional<FunctionData> create(const CallExpr *CE,
const CheckerContext &C) {
const FunctionDecl *FDecl = C.getCalleeDecl(CE);
if (!FDecl || (FDecl->getKind() != Decl::Function &&
FDecl->getKind() != Decl::CXXMethod))
return None;

StringRef Name = C.getCalleeName(FDecl);
std::string FullName = FDecl->getQualifiedNameAsString();
if (Name.empty() || FullName.empty())
return None;

return FunctionData{FDecl, Name, FullName};
}

bool isInScope(StringRef Scope) const {
return StringRef(FullName).startswith(Scope);
}

const FunctionDecl *const FDecl;
const StringRef Name;
const std::string FullName;
};

/// Catch taint related bugs. Check if tainted data is passed to a
/// system call etc. Returns true on matching.
bool checkPre(const CallExpr *CE, const FunctionDecl *FDecl, StringRef Name,
bool checkPre(const CallExpr *CE, const FunctionData &FData,
CheckerContext &C) const;

/// Add taint sources on a pre-visit. Returns true on matching.
bool addSourcesPre(const CallExpr *CE, const FunctionDecl *FDecl,
StringRef Name, CheckerContext &C) const;
bool addSourcesPre(const CallExpr *CE, const FunctionData &FData,
CheckerContext &C) const;

/// Mark filter's arguments not tainted on a pre-visit. Returns true on
/// matching.
bool addFiltersPre(const CallExpr *CE, StringRef Name,
bool addFiltersPre(const CallExpr *CE, const FunctionData &FData,
CheckerContext &C) const;

/// Propagate taint generated at pre-visit. Returns true on matching.
Expand Down Expand Up @@ -149,16 +182,25 @@ class GenericTaintChecker
/// Check if tainted data is used as a custom sink's parameter.
static constexpr llvm::StringLiteral MsgCustomSink =
"Untrusted data is passed to a user-defined sink";
bool checkCustomSinks(const CallExpr *CE, StringRef Name,
bool checkCustomSinks(const CallExpr *CE, const FunctionData &FData,
CheckerContext &C) const;

/// Generate a report if the expression is tainted or points to tainted data.
bool generateReportIfTainted(const Expr *E, StringRef Msg,
CheckerContext &C) const;

struct TaintPropagationRule;
using NameRuleMap = llvm::StringMap<TaintPropagationRule>;
using NameArgMap = llvm::StringMap<ArgVector>;
template <typename T>
using ConfigDataMap =
std::unordered_multimap<std::string, std::pair<std::string, T>>;
using NameRuleMap = ConfigDataMap<TaintPropagationRule>;
using NameArgMap = ConfigDataMap<ArgVector>;

/// Find a function with the given name and scope. Returns the first match
/// or the end of the map.
template <typename T>
static auto findFunctionInConfig(const ConfigDataMap<T> &Map,
const FunctionData &FData);

/// A struct used to specify taint propagation rules for a function.
///
Expand Down Expand Up @@ -200,8 +242,7 @@ class GenericTaintChecker
/// Get the propagation rule for a given function.
static TaintPropagationRule
getTaintPropagationRule(const NameRuleMap &CustomPropagations,
const FunctionDecl *FDecl, StringRef Name,
CheckerContext &C);
const FunctionData &FData, CheckerContext &C);

void addSrcArg(unsigned A) { SrcArgs.push_back(A); }
void addDstArg(unsigned A) { DstArgs.push_back(A); }
Expand Down Expand Up @@ -236,14 +277,15 @@ class GenericTaintChecker
CheckerContext &C);
};

/// Defines a map between the propagation function's name and
/// TaintPropagationRule.
/// Defines a map between the propagation function's name, scope
/// and TaintPropagationRule.
NameRuleMap CustomPropagations;

/// Defines a map between the filter function's name and filtering args.
/// Defines a map between the filter function's name, scope and filtering
/// args.
NameArgMap CustomFilters;

/// Defines a map between the sink function's name and sinking args.
/// Defines a map between the sink function's name, scope and sinking args.
NameArgMap CustomSinks;
};

Expand All @@ -260,7 +302,7 @@ constexpr llvm::StringLiteral GenericTaintChecker::MsgCustomSink;
using TaintConfig = GenericTaintChecker::TaintConfiguration;

LLVM_YAML_IS_SEQUENCE_VECTOR(TaintConfig::Propagation)
LLVM_YAML_IS_SEQUENCE_VECTOR(TaintConfig::NameArgsPair)
LLVM_YAML_IS_SEQUENCE_VECTOR(TaintConfig::NameScopeArgs)

namespace llvm {
namespace yaml {
Expand All @@ -275,6 +317,7 @@ template <> struct MappingTraits<TaintConfig> {
template <> struct MappingTraits<TaintConfig::Propagation> {
static void mapping(IO &IO, TaintConfig::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,
Expand All @@ -292,10 +335,11 @@ template <> struct ScalarEnumerationTraits<GenericTaintChecker::VariadicType> {
}
};

template <> struct MappingTraits<TaintConfig::NameArgsPair> {
static void mapping(IO &IO, TaintConfig::NameArgsPair &NameArg) {
IO.mapRequired("Name", NameArg.first);
IO.mapRequired("Args", NameArg.second);
template <> struct MappingTraits<TaintConfig::NameScopeArgs> {
static void mapping(IO &IO, TaintConfig::NameScopeArgs &NSA) {
IO.mapRequired("Name", std::get<0>(NSA));
IO.mapOptional("Scope", std::get<1>(NSA));
IO.mapRequired("Args", std::get<2>(NSA));
}
};
} // namespace yaml
Expand Down Expand Up @@ -328,31 +372,51 @@ void GenericTaintChecker::parseConfiguration(CheckerManager &Mgr,
const std::string &Option,
TaintConfiguration &&Config) {
for (auto &P : Config.Propagations) {
GenericTaintChecker::CustomPropagations.try_emplace(
P.Name, std::move(P.SrcArgs),
convertToArgVector(Mgr, Option, P.DstArgs), P.VarType, P.VarIndex);
GenericTaintChecker::CustomPropagations.emplace(
P.Name,
std::make_pair(P.Scope, TaintPropagationRule{
std::move(P.SrcArgs),
convertToArgVector(Mgr, Option, P.DstArgs),
P.VarType, P.VarIndex}));
}

for (auto &F : Config.Filters) {
GenericTaintChecker::CustomFilters.try_emplace(F.first,
std::move(F.second));
GenericTaintChecker::CustomFilters.emplace(
std::get<0>(F),
std::make_pair(std::move(std::get<1>(F)), std::move(std::get<2>(F))));
}

for (auto &S : Config.Sinks) {
GenericTaintChecker::CustomSinks.try_emplace(S.first, std::move(S.second));
GenericTaintChecker::CustomSinks.emplace(
std::get<0>(S),
std::make_pair(std::move(std::get<1>(S)), std::move(std::get<2>(S))));
}
}

template <typename T>
auto GenericTaintChecker::findFunctionInConfig(const ConfigDataMap<T> &Map,
const FunctionData &FData) {
auto Range = Map.equal_range(FData.Name);
auto It =
std::find_if(Range.first, Range.second, [&FData](const auto &Entry) {
const auto &Value = Entry.second;
StringRef Scope = Value.first;
return Scope.empty() || FData.isInScope(Scope);
});
return It != Range.second ? It : Map.end();
}

GenericTaintChecker::TaintPropagationRule
GenericTaintChecker::TaintPropagationRule::getTaintPropagationRule(
const NameRuleMap &CustomPropagations, const FunctionDecl *FDecl,
StringRef Name, CheckerContext &C) {
const NameRuleMap &CustomPropagations, const FunctionData &FData,
CheckerContext &C) {
// TODO: Currently, we might lose precision here: we always mark a return
// value as tainted even if it's just a pointer, pointing to tainted data.

// Check for exact name match for functions without builtin substitutes.
// Use qualified name, because these are C functions without namespace.
TaintPropagationRule Rule =
llvm::StringSwitch<TaintPropagationRule>(Name)
llvm::StringSwitch<TaintPropagationRule>(FData.FullName)
// Source functions
// TODO: Add support for vfscanf & family.
.Case("fdopen", TaintPropagationRule({}, {ReturnValueIndex}))
Expand Down Expand Up @@ -397,6 +461,7 @@ GenericTaintChecker::TaintPropagationRule::getTaintPropagationRule(

// Check if it's one of the memory setting/copying functions.
// This check is specialized but faster then calling isCLibraryFunction.
const FunctionDecl *FDecl = FData.FDecl;
unsigned BId = 0;
if ((BId = FDecl->getMemoryFunctionKind()))
switch (BId) {
Expand Down Expand Up @@ -440,35 +505,32 @@ GenericTaintChecker::TaintPropagationRule::getTaintPropagationRule(
// or smart memory copy:
// - memccpy - copying until hitting a special character.

auto It = CustomPropagations.find(Name);
if (It != CustomPropagations.end())
return It->getValue();
auto It = findFunctionInConfig(CustomPropagations, FData);
if (It != CustomPropagations.end()) {
const auto &Value = It->second;
return Value.second;
}

return TaintPropagationRule();
}

void GenericTaintChecker::checkPreStmt(const CallExpr *CE,
CheckerContext &C) const {
const FunctionDecl *FDecl = C.getCalleeDecl(CE);
// Check for non-global functions.
if (!FDecl || FDecl->getKind() != Decl::Function)
return;

StringRef Name = C.getCalleeName(FDecl);
if (Name.empty())
Optional<FunctionData> FData = FunctionData::create(CE, C);
if (!FData)
return;

// Check for taintedness related errors first: system call, uncontrolled
// format string, tainted buffer size.
if (checkPre(CE, FDecl, Name, C))
if (checkPre(CE, *FData, C))
return;

// Marks the function's arguments and/or return value tainted if it present in
// the list.
if (addSourcesPre(CE, FDecl, Name, C))
if (addSourcesPre(CE, *FData, C))
return;

addFiltersPre(CE, Name, C);
addFiltersPre(CE, *FData, C);
}

void GenericTaintChecker::checkPostStmt(const CallExpr *CE,
Expand All @@ -484,12 +546,11 @@ void GenericTaintChecker::printState(raw_ostream &Out, ProgramStateRef State,
}

bool GenericTaintChecker::addSourcesPre(const CallExpr *CE,
const FunctionDecl *FDecl,
StringRef Name,
const FunctionData &FData,
CheckerContext &C) const {
// First, try generating a propagation rule for this function.
TaintPropagationRule Rule = TaintPropagationRule::getTaintPropagationRule(
this->CustomPropagations, FDecl, Name, C);
this->CustomPropagations, FData, C);
if (!Rule.isNull()) {
ProgramStateRef State = Rule.process(CE, C);
if (State) {
Expand All @@ -500,14 +561,16 @@ bool GenericTaintChecker::addSourcesPre(const CallExpr *CE,
return false;
}

bool GenericTaintChecker::addFiltersPre(const CallExpr *CE, StringRef Name,
bool GenericTaintChecker::addFiltersPre(const CallExpr *CE,
const FunctionData &FData,
CheckerContext &C) const {
auto It = CustomFilters.find(Name);
auto It = findFunctionInConfig(CustomFilters, FData);
if (It == CustomFilters.end())
return false;

ProgramStateRef State = C.getState();
const ArgVector &Args = It->getValue();
const auto &Value = It->second;
const ArgVector &Args = Value.second;
for (unsigned ArgNum : Args) {
if (ArgNum >= CE->getNumArgs())
continue;
Expand Down Expand Up @@ -564,19 +627,19 @@ bool GenericTaintChecker::propagateFromPre(const CallExpr *CE,
}

bool GenericTaintChecker::checkPre(const CallExpr *CE,
const FunctionDecl *FDecl, StringRef Name,
const FunctionData &FData,
CheckerContext &C) const {

if (checkUncontrolledFormatString(CE, C))
return true;

if (checkSystemCall(CE, Name, C))
if (checkSystemCall(CE, FData.Name, C))
return true;

if (checkTaintedBufferSize(CE, FDecl, C))
if (checkTaintedBufferSize(CE, FData.FDecl, C))
return true;

if (checkCustomSinks(CE, Name, C))
if (checkCustomSinks(CE, FData, C))
return true;

return false;
Expand All @@ -595,7 +658,7 @@ Optional<SVal> GenericTaintChecker::getPointedToSVal(CheckerContext &C,

QualType ArgTy = Arg->getType().getCanonicalType();
if (!ArgTy->isPointerType())
return None;
return State->getSVal(*AddrLoc);

QualType ValTy = ArgTy->getPointeeType();

Expand Down Expand Up @@ -848,13 +911,15 @@ bool GenericTaintChecker::checkTaintedBufferSize(const CallExpr *CE,
generateReportIfTainted(CE->getArg(ArgNum), MsgTaintedBufferSize, C);
}

bool GenericTaintChecker::checkCustomSinks(const CallExpr *CE, StringRef Name,
bool GenericTaintChecker::checkCustomSinks(const CallExpr *CE,
const FunctionData &FData,
CheckerContext &C) const {
auto It = CustomSinks.find(Name);
auto It = findFunctionInConfig(CustomSinks, FData);
if (It == CustomSinks.end())
return false;

const GenericTaintChecker::ArgVector &Args = It->getValue();
const auto &Value = It->second;
const GenericTaintChecker::ArgVector &Args = Value.second;
for (unsigned ArgNum : Args) {
if (ArgNum >= CE->getNumArgs())
continue;
Expand Down

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