48 48
#include "clang/CodeGen/ConstantInitBuilder.h"
49 49
#include "clang/Frontend/FrontendDiagnostic.h"
50 50
#include "llvm/ADT/STLExtras.h"
51 +
#include "llvm/ADT/StringExtras.h"
51 52
#include "llvm/ADT/StringSwitch.h"
52 53
#include "llvm/ADT/Triple.h"
53 54
#include "llvm/Analysis/TargetLibraryInfo.h"
67 68
#include "llvm/Support/MD5.h"
68 69
#include "llvm/Support/TimeProfiler.h"
69 70
#include "llvm/Support/X86TargetParser.h"
71 +
#include "llvm/Support/xxhash.h"
70 72 71 73
using namespace clang;
72 74
using namespace CodeGen;
@@ -577,6 +579,8 @@ void CodeGenModule::Release() {
577 579
CodeGenFunction(*this).EmitCfiCheckFail();
578 580
CodeGenFunction(*this).EmitCfiCheckStub();
579 581
}
582 +
if (LangOpts.Sanitize.has(SanitizerKind::KCFI))
583 +
finalizeKCFITypes();
580 584
emitAtAvailableLinkGuard();
581 585
if (Context.getTargetInfo().getTriple().isWasm())
582 586
EmitMainVoidAlias();
@@ -759,6 +763,9 @@ void CodeGenModule::Release() {
759 763
CodeGenOpts.SanitizeCfiCanonicalJumpTables);
760 764
}
761 765 766 +
if (LangOpts.Sanitize.has(SanitizerKind::KCFI))
767 +
getModule().addModuleFlag(llvm::Module::Override, "kcfi", 1);
768 + 762 769
if (CodeGenOpts.CFProtectionReturn &&
763 770
Target.checkCFProtectionReturnSupported(getDiags())) {
764 771
// Indicate that we want to instrument return control flow protection.
@@ -1669,6 +1676,20 @@ llvm::ConstantInt *CodeGenModule::CreateCrossDsoCfiTypeId(llvm::Metadata *MD) {
1669 1676
return llvm::ConstantInt::get(Int64Ty, llvm::MD5Hash(MDS->getString()));
1670 1677
}
1671 1678 1679 +
llvm::ConstantInt *CodeGenModule::CreateKCFITypeId(QualType T) {
1680 +
if (auto *FnType = T->getAs<FunctionProtoType>())
1681 +
T = getContext().getFunctionType(
1682 +
FnType->getReturnType(), FnType->getParamTypes(),
1683 +
FnType->getExtProtoInfo().withExceptionSpec(EST_None));
1684 + 1685 +
std::string OutName;
1686 +
llvm::raw_string_ostream Out(OutName);
1687 +
getCXXABI().getMangleContext().mangleTypeName(T, Out);
1688 + 1689 +
return llvm::ConstantInt::get(Int32Ty,
1690 +
static_cast<uint32_t>(llvm::xxHash64(OutName)));
1691 +
}
1692 + 1672 1693
void CodeGenModule::SetLLVMFunctionAttributes(GlobalDecl GD,
1673 1694
const CGFunctionInfo &Info,
1674 1695
llvm::Function *F, bool IsThunk) {
@@ -2287,6 +2308,57 @@ void CodeGenModule::CreateFunctionTypeMetadataForIcall(const FunctionDecl *FD,
2287 2308
F->addTypeMetadata(0, llvm::ConstantAsMetadata::get(CrossDsoTypeId));
2288 2309
}
2289 2310 2311 +
void CodeGenModule::setKCFIType(const FunctionDecl *FD, llvm::Function *F) {
2312 +
if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic())
2313 +
return;
2314 + 2315 +
llvm::LLVMContext &Ctx = F->getContext();
2316 +
llvm::MDBuilder MDB(Ctx);
2317 +
F->setMetadata(llvm::LLVMContext::MD_kcfi_type,
2318 +
llvm::MDNode::get(
2319 +
Ctx, MDB.createConstant(CreateKCFITypeId(FD->getType()))));
2320 +
}
2321 + 2322 +
static bool allowKCFIIdentifier(StringRef Name) {
2323 +
// KCFI type identifier constants are only necessary for external assembly
2324 +
// functions, which means it's safe to skip unusual names. Subset of
2325 +
// MCAsmInfo::isAcceptableChar() and MCAsmInfoXCOFF::isAcceptableChar().
2326 +
return llvm::all_of(Name, [](const char &C) {
2327 +
return llvm::isAlnum(C) || C == '_' || C == '.';
2328 +
});
2329 +
}
2330 + 2331 +
void CodeGenModule::finalizeKCFITypes() {
2332 +
llvm::Module &M = getModule();
2333 +
for (auto &F : M.functions()) {
2334 +
// Remove KCFI type metadata from non-address-taken local functions.
2335 +
bool AddressTaken = F.hasAddressTaken();
2336 +
if (!AddressTaken && F.hasLocalLinkage())
2337 +
F.eraseMetadata(llvm::LLVMContext::MD_kcfi_type);
2338 + 2339 +
// Generate a constant with the expected KCFI type identifier for all
2340 +
// address-taken function declarations to support annotating indirectly
2341 +
// called assembly functions.
2342 +
if (!AddressTaken || !F.isDeclaration())
2343 +
continue;
2344 + 2345 +
const llvm::ConstantInt *Type;
2346 +
if (const llvm::MDNode *MD = F.getMetadata(llvm::LLVMContext::MD_kcfi_type))
2347 +
Type = llvm::mdconst::extract<llvm::ConstantInt>(MD->getOperand(0));
2348 +
else
2349 +
continue;
2350 + 2351 +
StringRef Name = F.getName();
2352 +
if (!allowKCFIIdentifier(Name))
2353 +
continue;
2354 + 2355 +
std::string Asm = (".weak __kcfi_typeid_" + Name + "\n.set __kcfi_typeid_" +
2356 +
Name + ", " + Twine(Type->getZExtValue()) + "\n")
2357 +
.str();
2358 +
M.appendModuleInlineAsm(Asm);
2359 +
}
2360 +
}
2361 + 2290 2362
void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
2291 2363
bool IsIncompleteFunction,
2292 2364
bool IsThunk) {
@@ -2369,6 +2441,9 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
2369 2441
!CodeGenOpts.SanitizeCfiCanonicalJumpTables)
2370 2442
CreateFunctionTypeMetadataForIcall(FD, F);
2371 2443 2444 +
if (LangOpts.Sanitize.has(SanitizerKind::KCFI))
2445 +
setKCFIType(FD, F);
2446 + 2372 2447
if (getLangOpts().OpenMP && FD->hasAttr<OMPDeclareSimdDeclAttr>())
2373 2448
getOpenMPRuntime().emitDeclareSimdFunction(FD, F);
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