devnexen updated this revision to Diff 132578.
Repository:
rC Clang
https://reviews.llvm.org/D42645
Files:
include/clang/StaticAnalyzer/Checkers/Checkers.td
lib/StaticAnalyzer/Checkers/CMakeLists.txt
lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
Index: lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
+++ lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
@@ -0,0 +1,78 @@
+// MmapWriteExecChecker.cpp - Check for the prot argument -----------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// 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 "ClangSACheckers.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;
+ static int ProtWrite;
+ static int ProtExec;
+ mutable std::unique_ptr<BugType> BT;
+public:
+ MmapWriteExecChecker() : MmapFn("mmap") {}
+ void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
+};
+}
+
+int MmapWriteExecChecker::ProtWrite = 0x02;
+int MmapWriteExecChecker::ProtExec = 0x04;
+
+void MmapWriteExecChecker::checkPreCall(const CallEvent &Call,
+ CheckerContext &C) const {
+ if (Call.isCalled(MmapFn)) {
+ if (Call.getNumArgs() < 3)
+ return;
+
+ llvm::Triple Triple = C.getASTContext().getTargetInfo().getTriple();
+
+ if (Triple.isOSGlibc())
+ ProtExec = 0x01;
+
+ SVal ProtVal = Call.getArgSVal(2);
+ Optional<nonloc::ConcreteInt> ProtLoc = ProtVal.getAs<nonloc::ConcreteInt>();
+ int64_t Prot = ProtLoc->getValue().getSExtValue();
+
+ 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 = llvm::make_unique<BugReport>(
+ *BT, "Both PROT_WRITE and PROT_EXEC flags had been set. It can "
+ "leads to exploitable memory regions, overwritten with malicious code"
+ , N);
+ Report->addRange(Call.getArgSourceRange(2));
+ C.emitReport(std::move(Report));
+ }
+ }
+}
+
+void ento::registerMmapWriteExecChecker(CheckerManager &mgr) {
+ mgr.registerChecker<MmapWriteExecChecker>();
+}
Index: lib/StaticAnalyzer/Checkers/CMakeLists.txt
===================================================================
--- lib/StaticAnalyzer/Checkers/CMakeLists.txt
+++ lib/StaticAnalyzer/Checkers/CMakeLists.txt
@@ -49,6 +49,7 @@
MallocChecker.cpp
MallocOverflowSecurityChecker.cpp
MallocSizeofChecker.cpp
+ MmapWriteExecChecker.cpp
MisusedMovedObjectChecker.cpp
MPI-Checker/MPIBugReporter.cpp
MPI-Checker/MPIChecker.cpp
Index: include/clang/StaticAnalyzer/Checkers/Checkers.td
===================================================================
--- include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -86,7 +86,7 @@
// The APIModeling package is for checkers that model APIs and don't perform
// any diagnostics. These checkers are always turned on; this package is
-// intended for API modeling that is not controlled by the target triple.
+// intended for API modeling that is not controlled by the the target triple.
def APIModeling : Package<"apiModeling">, Hidden;
def GoogleAPIModeling : Package<"google">, InPackage<APIModeling>;
@@ -394,6 +394,10 @@
def FloatLoopCounter : Checker<"FloatLoopCounter">,
HelpText<"Warn on using a floating point value as a loop counter (CERT: FLP30-C, FLP30-CPP)">,
DescFile<"CheckSecuritySyntaxOnly.cpp">;
+
+ def MmapWriteExecChecker : Checker<"MmapWriteExec">,
+ HelpText<"Check if mmap() call is not both writable and executable">,
+ DescFile<"MmapWriteExecChecker.cpp">;
}
let ParentPackage = SecurityAlpha in {
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