forked from OSchip/llvm-project
94 lines
3.2 KiB
C++
94 lines
3.2 KiB
C++
// MmapWriteExecChecker.cpp - Check for the prot argument -----------------===//
|
|
//
|
|
// 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 tests the 3rd argument of mmap's calls to check if
|
|
// it is writable and executable in the same time. It's somehow
|
|
// an optional checker since for example in JIT libraries it is pretty common.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
|
|
|
|
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
|
|
#include "clang/StaticAnalyzer/Core/Checker.h"
|
|
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
|
|
|
|
using namespace clang;
|
|
using namespace ento;
|
|
using llvm::APSInt;
|
|
|
|
namespace {
|
|
class MmapWriteExecChecker : public Checker<check::PreCall> {
|
|
CallDescription MmapFn;
|
|
CallDescription MprotectFn;
|
|
static int ProtWrite;
|
|
static int ProtExec;
|
|
static int ProtRead;
|
|
mutable std::unique_ptr<BugType> BT;
|
|
public:
|
|
MmapWriteExecChecker() : MmapFn("mmap", 6), MprotectFn("mprotect", 3) {}
|
|
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
|
|
int ProtExecOv;
|
|
int ProtReadOv;
|
|
};
|
|
}
|
|
|
|
int MmapWriteExecChecker::ProtWrite = 0x02;
|
|
int MmapWriteExecChecker::ProtExec = 0x04;
|
|
int MmapWriteExecChecker::ProtRead = 0x01;
|
|
|
|
void MmapWriteExecChecker::checkPreCall(const CallEvent &Call,
|
|
CheckerContext &C) const {
|
|
if (Call.isCalled(MmapFn) || Call.isCalled(MprotectFn)) {
|
|
SVal ProtVal = Call.getArgSVal(2);
|
|
Optional<nonloc::ConcreteInt> ProtLoc = ProtVal.getAs<nonloc::ConcreteInt>();
|
|
int64_t Prot = ProtLoc->getValue().getSExtValue();
|
|
if (ProtExecOv != ProtExec)
|
|
ProtExec = ProtExecOv;
|
|
if (ProtReadOv != ProtRead)
|
|
ProtRead = ProtReadOv;
|
|
|
|
// Wrong settings
|
|
if (ProtRead == ProtExec)
|
|
return;
|
|
|
|
if ((Prot & (ProtWrite | ProtExec)) == (ProtWrite | ProtExec)) {
|
|
if (!BT)
|
|
BT.reset(new BugType(this, "W^X check fails, Write Exec prot flags set", "Security"));
|
|
|
|
ExplodedNode *N = C.generateNonFatalErrorNode();
|
|
if (!N)
|
|
return;
|
|
|
|
auto Report = std::make_unique<PathSensitiveBugReport>(
|
|
*BT, "Both PROT_WRITE and PROT_EXEC flags are set. This can "
|
|
"lead to exploitable memory regions, which could be overwritten "
|
|
"with malicious code", N);
|
|
Report->addRange(Call.getArgSourceRange(2));
|
|
C.emitReport(std::move(Report));
|
|
}
|
|
}
|
|
}
|
|
|
|
void ento::registerMmapWriteExecChecker(CheckerManager &mgr) {
|
|
MmapWriteExecChecker *Mwec =
|
|
mgr.registerChecker<MmapWriteExecChecker>();
|
|
Mwec->ProtExecOv =
|
|
mgr.getAnalyzerOptions()
|
|
.getCheckerIntegerOption(Mwec, "MmapProtExec");
|
|
Mwec->ProtReadOv =
|
|
mgr.getAnalyzerOptions()
|
|
.getCheckerIntegerOption(Mwec, "MmapProtRead");
|
|
}
|
|
|
|
bool ento::shouldRegisterMmapWriteExecChecker(const CheckerManager &mgr) {
|
|
return true;
|
|
}
|