Implement Control Flow Integrity for virtual calls.

This patch introduces the -fsanitize=cfi-vptr flag, which enables a control
flow integrity scheme that checks that virtual calls take place using a vptr of
the correct dynamic type. More details in the new docs/ControlFlowIntegrity.rst
file.

It also introduces the -fsanitize=cfi flag, which is currently a synonym for
-fsanitize=cfi-vptr, but will eventually cover all CFI checks implemented
in Clang.

Differential Revision: http://reviews.llvm.org/D7424

llvm-svn: 230055

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 14a2890b29c..e580969ce5b 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1281,6 +1281,8 @@ void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
       cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") &&
       DC->getParent()->isTranslationUnit())
     EmitFundamentalRTTIDescriptors();
+
+  CGM.EmitVTableBitSetEntries(VTable, VTLayout);
 }
 
 llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor(
@@ -1372,6 +1374,8 @@ llvm::Value *ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
   Ty = Ty->getPointerTo()->getPointerTo();
   llvm::Value *VTable = CGF.GetVTablePtr(This, Ty);
 
+  CGF.EmitVTablePtrCheckForCall(cast<CXXMethodDecl>(GD.getDecl()), VTable);
+
   uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD);
   llvm::Value *VFuncPtr =
       CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn");