https://github.com/tru updated https://github.com/llvm/llvm-project/pull/153725
>From 7575bda7e1904308b5780ffe09c51b68d18b48da Mon Sep 17 00:00:00 2001
From: Oliver Hunt <oli...@apple.com>
Date: Wed, 13 Aug 2025 22:01:24 -0700
Subject: [PATCH 1/2] [clang][Obj-C][PAC] Add support for authenticating block
metadata (#152978)
Introduces the use of pointer authentication to protect the invocation,
copy and dispose, reference, and descriptor pointers in Objective-C
block objects.
Resolves #141176
---
clang/include/clang/Basic/Features.def | 1 +
.../include/clang/Basic/PointerAuthOptions.h | 16 +++
clang/lib/CodeGen/Address.h | 5 +
clang/lib/CodeGen/CGBlocks.cpp | 99 +++++++++++++------
clang/lib/Driver/ToolChains/Clang.cpp | 1 -
clang/lib/Frontend/CompilerInvocation.cpp | 11 ++-
clang/test/CodeGen/ptrauth-qualifier-blocks.c | 10 +-
.../ptrauth-block-descriptor-pointer.m | 28 ++++++
clang/test/CodeGenObjC/ptrauth-block-isa.m | 5 +-
9 files changed, 142 insertions(+), 34 deletions(-)
create mode 100644 clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
diff --git a/clang/include/clang/Basic/Features.def
b/clang/include/clang/Basic/Features.def
index 5cc3569ab4a94..16604057d2da7 100644
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -157,6 +157,7 @@ FEATURE(ptrauth_vtable_pointer_address_discrimination,
LangOpts.PointerAuthVTPtr
FEATURE(ptrauth_vtable_pointer_type_discrimination,
LangOpts.PointerAuthVTPtrTypeDiscrimination)
FEATURE(ptrauth_type_info_vtable_pointer_discrimination,
LangOpts.PointerAuthTypeInfoVTPtrDiscrimination)
FEATURE(ptrauth_member_function_pointer_type_discrimination,
LangOpts.PointerAuthCalls)
+FEATURE(ptrauth_signed_block_descriptors, LangOpts.PointerAuthCalls)
FEATURE(ptrauth_function_pointer_type_discrimination,
LangOpts.PointerAuthFunctionTypeDiscrimination)
FEATURE(ptrauth_indirect_gotos, LangOpts.PointerAuthIndirectGotos)
FEATURE(ptrauth_init_fini, LangOpts.PointerAuthInitFini)
diff --git a/clang/include/clang/Basic/PointerAuthOptions.h
b/clang/include/clang/Basic/PointerAuthOptions.h
index fb6dddf3ae9ce..2b920250721fc 100644
--- a/clang/include/clang/Basic/PointerAuthOptions.h
+++ b/clang/include/clang/Basic/PointerAuthOptions.h
@@ -23,6 +23,10 @@
namespace clang {
+/// Constant discriminator to be used with block descriptor pointers. The value
+/// is ptrauth_string_discriminator("block_descriptor")
+constexpr uint16_t BlockDescriptorConstantDiscriminator = 0xC0BB;
+
/// Constant discriminator to be used with function pointers in .init_array and
/// .fini_array. The value is ptrauth_string_discriminator("init_fini")
constexpr uint16_t InitFiniPointerConstantDiscriminator = 0xD9D4;
@@ -223,6 +227,18 @@ struct PointerAuthOptions {
/// The ABI for function addresses in .init_array and .fini_array
PointerAuthSchema InitFiniPointers;
+ /// The ABI for block invocation function pointers.
+ PointerAuthSchema BlockInvocationFunctionPointers;
+
+ /// The ABI for block object copy/destroy function pointers.
+ PointerAuthSchema BlockHelperFunctionPointers;
+
+ /// The ABI for __block variable copy/destroy function pointers.
+ PointerAuthSchema BlockByrefHelperFunctionPointers;
+
+ /// The ABI for pointers to block descriptors.
+ PointerAuthSchema BlockDescriptorPointers;
+
/// The ABI for Objective-C method lists.
PointerAuthSchema ObjCMethodListFunctionPointers;
diff --git a/clang/lib/CodeGen/Address.h b/clang/lib/CodeGen/Address.h
index a748ddaa110a5..4e7f3561ac049 100644
--- a/clang/lib/CodeGen/Address.h
+++ b/clang/lib/CodeGen/Address.h
@@ -176,6 +176,11 @@ class Address {
static Address invalid() { return Address(nullptr); }
bool isValid() const { return Pointer.getPointer() != nullptr; }
+ llvm::Value *getPointerIfNotSigned() const {
+ assert(isValid() && "pointer isn't valid");
+ return !isSigned() ? Pointer.getPointer() : nullptr;
+ }
+
/// This function is used in situations where the caller is doing some sort
of
/// opaque "laundering" of the pointer.
void replaceBasePointer(llvm::Value *P) {
diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 1aba841eb5fc2..c1f5b983f7233 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -188,13 +188,14 @@ static llvm::Constant *buildBlockDescriptor(CodeGenModule
&CGM,
// Optional copy/dispose helpers.
bool hasInternalHelper = false;
if (blockInfo.NeedsCopyDispose) {
+ auto &Schema =
CGM.getCodeGenOpts().PointerAuth.BlockHelperFunctionPointers;
// copy_func_helper_decl
llvm::Constant *copyHelper = buildCopyHelper(CGM, blockInfo);
- elements.add(copyHelper);
+ elements.addSignedPointer(copyHelper, Schema, GlobalDecl(), QualType());
// destroy_func_decl
llvm::Constant *disposeHelper = buildDisposeHelper(CGM, blockInfo);
- elements.add(disposeHelper);
+ elements.addSignedPointer(disposeHelper, Schema, GlobalDecl(), QualType());
if (cast<llvm::Function>(copyHelper->stripPointerCasts())
->hasInternalLinkage() ||
@@ -567,9 +568,8 @@ static void computeBlockInfo(CodeGenModule &CGM,
CodeGenFunction *CGF,
llvm::StructType::get(CGM.getLLVMContext(), elementTypes, true);
info.CanBeGlobal = true;
return;
- }
- else if (C.getLangOpts().ObjC &&
- CGM.getLangOpts().getGC() == LangOptions::NonGC)
+ } else if (C.getLangOpts().ObjC &&
+ CGM.getLangOpts().getGC() == LangOptions::NonGC)
info.HasCapturedVariableLayout = true;
if (block->doesNotEscape())
@@ -783,7 +783,7 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const
BlockExpr *blockExpr) {
llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) {
bool IsOpenCL = CGM.getContext().getLangOpts().OpenCL;
- auto GenVoidPtrTy =
+ llvm::PointerType *GenVoidPtrTy =
IsOpenCL ? CGM.getOpenCLRuntime().getGenericVoidPointerType() :
VoidPtrTy;
LangAS GenVoidPtrAddr = IsOpenCL ? LangAS::opencl_generic : LangAS::Default;
auto GenVoidPtrSize = CharUnits::fromQuantity(
@@ -817,9 +817,6 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const
CGBlockInfo &blockInfo) {
: CGM.getNSConcreteStackBlock();
isa = blockISA;
- // Build the block descriptor.
- descriptor = buildBlockDescriptor(CGM, blockInfo);
-
// Compute the initial on-stack block flags.
if (!CGM.getCodeGenOpts().DisableBlockSignatureString)
flags = BLOCK_HAS_SIGNATURE;
@@ -833,6 +830,9 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const
CGBlockInfo &blockInfo) {
flags |= BLOCK_USE_STRET;
if (blockInfo.NoEscape)
flags |= BLOCK_IS_NOESCAPE | BLOCK_IS_GLOBAL;
+
+ // Build the block descriptor.
+ descriptor = buildBlockDescriptor(CGM, blockInfo);
}
auto projectField = [&](unsigned index, const Twine &name) -> Address {
@@ -883,11 +883,25 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const
CGBlockInfo &blockInfo) {
llvm::ConstantInt::get(IntTy, blockInfo.BlockAlign.getQuantity()),
getIntSize(), "block.align");
}
- addHeaderField(blockFn, GenVoidPtrSize, "block.invoke");
- if (!IsOpenCL)
- addHeaderField(descriptor, getPointerSize(), "block.descriptor");
- else if (auto *Helper =
- CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
+
+ if (!IsOpenCL) {
+ llvm::Value *blockFnPtr =
+ llvm::ConstantExpr::getBitCast(InvokeFn, VoidPtrTy);
+ QualType type = blockInfo.getBlockExpr()
+ ->getType()
+ ->castAs<BlockPointerType>()
+ ->getPointeeType();
+ addSignedHeaderField(
+ blockFnPtr,
+ CGM.getCodeGenOpts().PointerAuth.BlockInvocationFunctionPointers,
+ GlobalDecl(), type, getPointerSize(), "block.invoke");
+
+ addSignedHeaderField(
+ descriptor, CGM.getCodeGenOpts().PointerAuth.BlockDescriptorPointers,
+ GlobalDecl(), type, getPointerSize(), "block.descriptor");
+ } else if (auto *Helper =
+ CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
+ addHeaderField(blockFn, GenVoidPtrSize, "block.invoke");
for (auto I : Helper->getCustomFieldValues(*this, blockInfo)) {
addHeaderField(
I.first,
@@ -895,7 +909,8 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const
CGBlockInfo &blockInfo) {
CGM.getDataLayout().getTypeAllocSize(I.first->getType())),
I.second);
}
- }
+ } else
+ addHeaderField(blockFn, GenVoidPtrSize, "block.invoke");
}
// Finally, capture all the values into the block.
@@ -1166,6 +1181,8 @@ RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr
*E,
ASTContext &Ctx = getContext();
CallArgList Args;
+ llvm::Value *FuncPtr = nullptr;
+
if (getLangOpts().OpenCL) {
// For OpenCL, BlockPtr is already casted to generic block literal.
@@ -1185,7 +1202,7 @@ RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr
*E,
if (!isa<ParmVarDecl>(E->getCalleeDecl()))
Func = CGM.getOpenCLRuntime().getInvokeFunction(E->getCallee());
else {
- llvm::Value *FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 2);
+ FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 2);
Func = Builder.CreateAlignedLoad(GenericVoidPtrTy, FuncPtr,
getPointerAlign());
}
@@ -1194,7 +1211,7 @@ RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr
*E,
BlockPtr =
Builder.CreatePointerCast(BlockPtr, UnqualPtrTy, "block.literal");
// Get pointer to the block invoke function
- llvm::Value *FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 3);
+ FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 3);
// First argument is a block literal casted to a void pointer
BlockPtr = Builder.CreatePointerCast(BlockPtr, VoidPtrTy);
@@ -1211,7 +1228,15 @@ RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr
*E,
CGM.getTypes().arrangeBlockFunctionCall(Args, FuncTy);
// Prepare the callee.
- CGCallee Callee(CGCalleeInfo(), Func);
+ CGPointerAuthInfo PointerAuth;
+ if (auto &AuthSchema =
+ CGM.getCodeGenOpts().PointerAuth.BlockInvocationFunctionPointers) {
+ assert(FuncPtr != nullptr && "Missing function pointer for AuthInfo");
+ PointerAuth =
+ EmitPointerAuthInfo(AuthSchema, FuncPtr, GlobalDecl(), FnType);
+ }
+
+ CGCallee Callee(CGCalleeInfo(), Func, PointerAuth);
// And call the block.
return EmitCall(FnInfo, Callee, ReturnValue, Args, CallOrInvoke);
@@ -1295,14 +1320,15 @@ static llvm::Constant *buildGlobalBlock(CodeGenModule
&CGM,
bool IsOpenCL = CGM.getLangOpts().OpenCL;
bool IsWindows = CGM.getTarget().getTriple().isOSWindows();
+ auto &CGOPointerAuth = CGM.getCodeGenOpts().PointerAuth;
if (!IsOpenCL) {
// isa
if (IsWindows)
fields.addNullPointer(CGM.Int8PtrPtrTy);
else
fields.addSignedPointer(CGM.getNSConcreteGlobalBlock(),
- CGM.getCodeGenOpts().PointerAuth.ObjCIsaPointers,
- GlobalDecl(), QualType());
+ CGOPointerAuth.ObjCIsaPointers, GlobalDecl(),
+ QualType());
// __flags
BlockFlags flags = BLOCK_IS_GLOBAL;
@@ -1321,11 +1347,20 @@ static llvm::Constant *buildGlobalBlock(CodeGenModule
&CGM,
}
// Function
- fields.add(blockFn);
+ if (auto &Schema = CGOPointerAuth.BlockInvocationFunctionPointers) {
+ QualType FnType = blockInfo.getBlockExpr()
+ ->getType()
+ ->castAs<BlockPointerType>()
+ ->getPointeeType();
+ fields.addSignedPointer(blockFn, Schema, GlobalDecl(), FnType);
+ } else
+ fields.add(blockFn);
if (!IsOpenCL) {
// Descriptor
- fields.add(buildBlockDescriptor(CGM, blockInfo));
+ llvm::Constant *Descriptor = buildBlockDescriptor(CGM, blockInfo);
+ fields.addSignedPointer(Descriptor, CGOPointerAuth.BlockDescriptorPointers,
+ GlobalDecl(), QualType());
} else if (auto *Helper =
CGM.getTargetCodeGenInfo().getTargetOpenCLBlockHelper()) {
for (auto *I : Helper->getCustomFieldValues(CGM, blockInfo)) {
@@ -1995,8 +2030,8 @@ CodeGenFunction::GenerateCopyHelperFunction(const
CGBlockInfo &blockInfo) {
// it. It's not quite worth the annoyance to avoid creating it in the
// first place.
if (!needsEHCleanup(captureType.isDestructedType()))
- if (auto *I =
- cast_or_null<llvm::Instruction>(dstField.getBasePointer()))
+ if (auto *I = cast_or_null<llvm::Instruction>(
+ dstField.getPointerIfNotSigned()))
I->eraseFromParent();
}
break;
@@ -2730,8 +2765,16 @@ void CodeGenFunction::emitByrefStructureInit(const
AutoVarEmission &emission) {
unsigned nextHeaderIndex = 0;
CharUnits nextHeaderOffset;
auto storeHeaderField = [&](llvm::Value *value, CharUnits fieldSize,
- const Twine &name) {
+ const Twine &name, bool isFunction = false) {
auto fieldAddr = Builder.CreateStructGEP(addr, nextHeaderIndex, name);
+ if (isFunction) {
+ if (auto &Schema = CGM.getCodeGenOpts()
+ .PointerAuth.BlockByrefHelperFunctionPointers) {
+ auto PointerAuth = EmitPointerAuthInfo(
+ Schema, fieldAddr.emitRawPointer(*this), GlobalDecl(), QualType());
+ value = EmitPointerAuthSign(PointerAuth, value);
+ }
+ }
Builder.CreateStore(value, fieldAddr);
nextHeaderIndex++;
@@ -2814,10 +2857,10 @@ void CodeGenFunction::emitByrefStructureInit(const
AutoVarEmission &emission) {
storeHeaderField(V, getIntSize(), "byref.size");
if (helpers) {
- storeHeaderField(helpers->CopyHelper, getPointerSize(),
- "byref.copyHelper");
+ storeHeaderField(helpers->CopyHelper, getPointerSize(), "byref.copyHelper",
+ /*isFunction=*/true);
storeHeaderField(helpers->DisposeHelper, getPointerSize(),
- "byref.disposeHelper");
+ "byref.disposeHelper", /*isFunction=*/true);
}
if (ByRefHasLifetime && HasByrefExtendedLayout) {
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp
b/clang/lib/Driver/ToolChains/Clang.cpp
index bf5f427fbfbb4..62613322320cd 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1752,7 +1752,6 @@ void Clang::AddAArch64TargetArgs(const ArgList &Args,
options::OPT_fno_ptrauth_objc_interface_sel);
Args.addOptInFlag(CmdArgs, options::OPT_fptrauth_objc_class_ro,
options::OPT_fno_ptrauth_objc_class_ro);
-
if (Triple.getEnvironment() == llvm::Triple::PAuthTest)
handlePAuthABI(Args, CmdArgs);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp
b/clang/lib/Frontend/CompilerInvocation.cpp
index 08cf0ae6b2c24..88886bf945aeb 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1542,6 +1542,16 @@ void CompilerInvocation::setDefaultPointerAuthOptions(
Discrimination::Constant, InitFiniPointerConstantDiscriminator);
}
+ Opts.BlockInvocationFunctionPointers =
+ PointerAuthSchema(Key::ASIA, true, Discrimination::None);
+ Opts.BlockHelperFunctionPointers =
+ PointerAuthSchema(Key::ASIA, true, Discrimination::None);
+ Opts.BlockByrefHelperFunctionPointers =
+ PointerAuthSchema(Key::ASIA, true, Discrimination::None);
+ Opts.BlockDescriptorPointers =
+ PointerAuthSchema(Key::ASDA, true, Discrimination::Constant,
+ BlockDescriptorConstantDiscriminator);
+
Opts.ObjCMethodListFunctionPointers =
PointerAuthSchema(Key::ASIA, true, Discrimination::None);
Opts.ObjCMethodListPointer =
@@ -3621,7 +3631,6 @@ static void ParsePointerAuthArgs(LangOptions &Opts,
ArgList &Args,
Opts.PointerAuthELFGOT = Args.hasArg(OPT_fptrauth_elf_got);
Opts.AArch64JumpTableHardening =
Args.hasArg(OPT_faarch64_jump_table_hardening);
-
Opts.PointerAuthObjcIsa = Args.hasArg(OPT_fptrauth_objc_isa);
Opts.PointerAuthObjcClassROPointers =
Args.hasArg(OPT_fptrauth_objc_class_ro);
Opts.PointerAuthObjcInterfaceSel =
diff --git a/clang/test/CodeGen/ptrauth-qualifier-blocks.c
b/clang/test/CodeGen/ptrauth-qualifier-blocks.c
index 62da59cf327f6..f460da205cac7 100644
--- a/clang/test/CodeGen/ptrauth-qualifier-blocks.c
+++ b/clang/test/CodeGen/ptrauth-qualifier-blocks.c
@@ -82,9 +82,15 @@ void test_block_address_byref_capture() {
// CHECK: store i32 33554432,
// CHECK: store i32 48,
// CHECK: [[COPY_HELPER_FIELD:%.*]] = getelementptr inbounds nuw
[[BYREF_T]], ptr [[BYREF]], i32 0, i32 4
- // CHECK: store ptr @__Block_byref_object_copy_, ptr [[COPY_HELPER_FIELD]],
align
+ // CHECK: [[T0:%.*]] = ptrtoint ptr [[COPY_HELPER_FIELD]] to i64
+ // CHECK: [[T1:%.*]] = call i64 @llvm.ptrauth.sign(i64 ptrtoint (ptr
@__Block_byref_object_copy_ to i64), i32 0, i64 [[T0]])
+ // CHECK: [[T2:%.*]] = inttoptr i64 [[T1]] to ptr
+ // CHECK: store ptr [[T2]], ptr [[COPY_HELPER_FIELD]], align
// CHECK: [[DISPOSE_HELPER_FIELD:%.*]] = getelementptr inbounds nuw
[[BYREF_T]], ptr [[BYREF]], i32 0, i32 5
- // CHECK: store ptr @__Block_byref_object_dispose_, ptr
[[DISPOSE_HELPER_FIELD]], align
+ // CHECK: [[T0:%.*]] = ptrtoint ptr [[DISPOSE_HELPER_FIELD]] to i64
+ // CHECK: [[T1:%.*]] = call i64 @llvm.ptrauth.sign(i64 ptrtoint (ptr
@__Block_byref_object_dispose_ to i64), i32 0, i64 [[T0]])
+ // CHECK: [[T2:%.*]] = inttoptr i64 [[T1]] to ptr
+ // CHECK: store ptr [[T2]], ptr [[DISPOSE_HELPER_FIELD]], align
// flags - copy/dispose required
// CHECK: store i32 1107296256, ptr
__block struct A * __ptrauth(1, 1, 60) ptr = createA();
diff --git a/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
b/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
new file mode 100644
index 0000000000000..559cddfd4e866
--- /dev/null
+++ b/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -fobjc-arc -fblocks -fptrauth-calls -triple
arm64e-apple-ios -emit-llvm -o - %s | FileCheck %s
+
+_Static_assert(__has_feature(ptrauth_signed_block_descriptors),
"-fptrauth-block-descriptor-pointers should set
ptrauth_signed_block_descriptors");
+
+void a() {
+ // Test out a global block.
+ void (^blk)(void) = ^{};
+}
+
+// CHECK: [[BLOCK_DESCRIPTOR_NAME:@"__block_descriptor_.*"]] = linkonce_odr
hidden unnamed_addr constant { i64, i64, ptr, ptr } { i64 0, i64 32, ptr @.str,
ptr null }
+
+
+// CHECK: @__block_literal_global = internal constant { ptr, i32, i32, ptr,
ptr } { ptr @_NSConcreteGlobalBlock, i32 1342177280, i32 0, ptr ptrauth (ptr
@__a_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({ ptr, i32, i32,
ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr ptrauth (ptr
@"__block_descriptor_32_e5_v8\01?0l", i32 2, i64 49339, ptr getelementptr
inbounds ({ ptr, i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32
4)) }
+
+void b(int p) {
+ // CHECK-LABEL: define void @b
+
+ // Test out a stack block.
+ void (^blk)(void) = ^{(void)p;};
+
+ // CHECK: [[BLOCK:%.*]] = alloca <{ ptr, i32, i32, ptr, ptr, i32 }>
+ // CHECK: [[BLOCK_DESCRIPTOR_REF:%.*]] = getelementptr inbounds nuw <{
{{.*}} }>, ptr [[BLOCK]], i32 0, i32 4
+ // CHECK: [[BLOCK_DESCRIPTOR_REF_INT:%.*]] = ptrtoint ptr
[[BLOCK_DESCRIPTOR_REF]] to i64
+ // CHECK: [[BLENDED:%.*]] = call i64 @llvm.ptrauth.blend(i64
[[BLOCK_DESCRIPTOR_REF_INT]], i64 49339)
+ // CHECK: [[SIGNED_REF:%.*]] = call i64 @llvm.ptrauth.sign(i64 ptrtoint (ptr
@"__block_descriptor_36_e5_v8\01?0l" to i64), i32 2, i64 [[BLENDED]])
+ // CHECK: [[SIGNED_REF_PTR:%.*]] = inttoptr i64 [[SIGNED_REF]] to ptr
+ // CHECK: store ptr [[SIGNED_REF_PTR]], ptr [[BLOCK_DESCRIPTOR_REF]]
+}
diff --git a/clang/test/CodeGenObjC/ptrauth-block-isa.m
b/clang/test/CodeGenObjC/ptrauth-block-isa.m
index c1e98c6fd9d3e..c37fe8b0d7fec 100644
--- a/clang/test/CodeGenObjC/ptrauth-block-isa.m
+++ b/clang/test/CodeGenObjC/ptrauth-block-isa.m
@@ -1,7 +1,8 @@
-// RUN: %clang_cc1 -fptrauth-calls -fptrauth-objc-isa -fobjc-arc -fblocks
-triple arm64e -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -fptrauth-calls -fptrauth-objc-isa -fobjc-arc -fblocks
-triple arm64e -emit-llvm %s -o - | FileCheck %s
void (^globalblock)(void) = ^{};
-// CHECK: [[GLOBAL_BLOCK:@.*]] = internal constant { ptr, i32, i32, ptr, ptr }
{ ptr ptrauth (ptr @_NSConcreteGlobalBlock, i32 2, i64 27361, ptr
[[GLOBAL_BLOCK]]), i32 1342177280, i32 0, ptr @globalblock_block_invoke, ptr
@"__block_descriptor_32_e5_v8\01?0l" }, align 8 #0
+// CHECK: [[BLOCK_DESCRIPTOR_NAME:@"__block_descriptor_.*"]] = linkonce_odr
hidden unnamed_addr constant { i64, i64, ptr, ptr } { i64 0, i64 32, ptr @.str,
ptr null }, comdat, align 8
+// CHECK: @__block_literal_global = internal constant { ptr, i32, i32, ptr,
ptr } { ptr ptrauth (ptr @_NSConcreteGlobalBlock, i32 2, i64 27361, ptr
@__block_literal_global), i32 1342177280, i32 0, ptr ptrauth (ptr
@globalblock_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({ ptr,
i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr ptrauth
(ptr [[BLOCK_DESCRIPTOR_NAME]], i32 2, i64 49339, ptr getelementptr inbounds ({
ptr, i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 4)) }
@interface A
- (int) count;
>From ad7bb1cc45a253d873198b9143fbe9c1e5d97aa5 Mon Sep 17 00:00:00 2001
From: Oliver Hunt <oli...@apple.com>
Date: Thu, 14 Aug 2025 17:20:27 -0700
Subject: [PATCH 2/2] [clang][Obj-C][PAC] Make block descriptor pointer signing
configurable (#153700)
Pointer auth protection of the block descriptor pointer is only
supported in some constrained environments so we do actually need it to
be configurable.
We had made it non configurable in the first PR to protect block
metadata because we believed that was an option but subsequently
realised it does need to remain configurable.
This PR revives the flags that permit this.
---
clang/include/clang/Basic/Features.def | 2 +-
clang/include/clang/Basic/LangOptions.def | 2 ++
clang/include/clang/Driver/Options.td | 1 +
clang/lib/Frontend/CompilerInvocation.cpp | 11 ++++++++---
.../ptrauth-block-descriptor-pointer.m | 15 +++++++++++++--
clang/test/CodeGenObjC/ptrauth-block-isa.m | 2 +-
6 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/clang/include/clang/Basic/Features.def
b/clang/include/clang/Basic/Features.def
index 16604057d2da7..b040181beaffd 100644
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -157,7 +157,7 @@ FEATURE(ptrauth_vtable_pointer_address_discrimination,
LangOpts.PointerAuthVTPtr
FEATURE(ptrauth_vtable_pointer_type_discrimination,
LangOpts.PointerAuthVTPtrTypeDiscrimination)
FEATURE(ptrauth_type_info_vtable_pointer_discrimination,
LangOpts.PointerAuthTypeInfoVTPtrDiscrimination)
FEATURE(ptrauth_member_function_pointer_type_discrimination,
LangOpts.PointerAuthCalls)
-FEATURE(ptrauth_signed_block_descriptors, LangOpts.PointerAuthCalls)
+FEATURE(ptrauth_signed_block_descriptors,
LangOpts.PointerAuthBlockDescriptorPointers)
FEATURE(ptrauth_function_pointer_type_discrimination,
LangOpts.PointerAuthFunctionTypeDiscrimination)
FEATURE(ptrauth_indirect_gotos, LangOpts.PointerAuthIndirectGotos)
FEATURE(ptrauth_init_fini, LangOpts.PointerAuthInitFini)
diff --git a/clang/include/clang/Basic/LangOptions.def
b/clang/include/clang/Basic/LangOptions.def
index f5a5d84eefb80..25f4575a54257 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -138,6 +138,8 @@ LANGOPT(PointerAuthObjcInterfaceSel, 1, 0, NotCompatible,
"authentication of SEL
LANGOPT(PointerAuthObjcInterfaceSelKey, 16, 0, NotCompatible, "authentication
key for SEL fields of ObjC interfaces")
LANGOPT(PointerAuthObjcClassROPointers, 1, 0, Benign, "class_ro_t pointer
authentication")
+LANGOPT(PointerAuthBlockDescriptorPointers, 1, 0, NotCompatible, "enable
signed block descriptors")
+
LANGOPT(DoubleSquareBracketAttributes, 1, 0, NotCompatible, "'[[]]' attributes
extension for all language standard modes")
LANGOPT(ExperimentalLateParseAttributes, 1, 0, NotCompatible, "experimental
late parsing of attributes")
diff --git a/clang/include/clang/Driver/Options.td
b/clang/include/clang/Driver/Options.td
index 18e4ab406ce4e..958d0d05ade29 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4527,6 +4527,7 @@ defm aarch64_jump_table_hardening:
OptInCC1FFlag<"aarch64-jump-table-hardening",
defm ptrauth_objc_isa : OptInCC1FFlag<"ptrauth-objc-isa", "Enable signing and
authentication of Objective-C object's 'isa' field">;
defm ptrauth_objc_interface_sel : OptInCC1FFlag<"ptrauth-objc-interface-sel",
"Enable signing and authentication of Objective-C object's 'SEL' fields">;
defm ptrauth_objc_class_ro : OptInCC1FFlag<"ptrauth-objc-class-ro", "Enable
signing and authentication for ObjC class_ro pointers">;
+defm ptrauth_block_descriptor_pointers :
OptInCC1FFlag<"ptrauth-block-descriptor-pointers", "Enable signing and
authentication of block descriptors">;
}
def fenable_matrix : Flag<["-"], "fenable-matrix">, Group<f_Group>,
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp
b/clang/lib/Frontend/CompilerInvocation.cpp
index 88886bf945aeb..08f3b7a7fcc49 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1548,9 +1548,10 @@ void CompilerInvocation::setDefaultPointerAuthOptions(
PointerAuthSchema(Key::ASIA, true, Discrimination::None);
Opts.BlockByrefHelperFunctionPointers =
PointerAuthSchema(Key::ASIA, true, Discrimination::None);
- Opts.BlockDescriptorPointers =
- PointerAuthSchema(Key::ASDA, true, Discrimination::Constant,
- BlockDescriptorConstantDiscriminator);
+ if (LangOpts.PointerAuthBlockDescriptorPointers)
+ Opts.BlockDescriptorPointers =
+ PointerAuthSchema(Key::ASDA, true, Discrimination::Constant,
+ BlockDescriptorConstantDiscriminator);
Opts.ObjCMethodListFunctionPointers =
PointerAuthSchema(Key::ASIA, true, Discrimination::None);
@@ -3608,6 +3609,8 @@ static void GeneratePointerAuthArgs(const LangOptions
&Opts,
GenerateArg(Consumer, OPT_fptrauth_objc_interface_sel);
if (Opts.PointerAuthObjcClassROPointers)
GenerateArg(Consumer, OPT_fptrauth_objc_class_ro);
+ if (Opts.PointerAuthBlockDescriptorPointers)
+ GenerateArg(Consumer, OPT_fptrauth_block_descriptor_pointers);
}
static void ParsePointerAuthArgs(LangOptions &Opts, ArgList &Args,
@@ -3631,6 +3634,8 @@ static void ParsePointerAuthArgs(LangOptions &Opts,
ArgList &Args,
Opts.PointerAuthELFGOT = Args.hasArg(OPT_fptrauth_elf_got);
Opts.AArch64JumpTableHardening =
Args.hasArg(OPT_faarch64_jump_table_hardening);
+ Opts.PointerAuthBlockDescriptorPointers =
+ Args.hasArg(OPT_fptrauth_block_descriptor_pointers);
Opts.PointerAuthObjcIsa = Args.hasArg(OPT_fptrauth_objc_isa);
Opts.PointerAuthObjcClassROPointers =
Args.hasArg(OPT_fptrauth_objc_class_ro);
Opts.PointerAuthObjcInterfaceSel =
diff --git a/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
b/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
index 559cddfd4e866..b51670fd6459a 100644
--- a/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
+++ b/clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m
@@ -1,6 +1,11 @@
-// RUN: %clang_cc1 -fobjc-arc -fblocks -fptrauth-calls -triple
arm64e-apple-ios -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -fobjc-arc -fblocks -fptrauth-calls
-fptrauth-block-descriptor-pointers -triple arm64e-apple-ios -emit-llvm -o -
%s | FileCheck %s
+// RUN: %clang_cc1 -fobjc-arc -fblocks -fptrauth-calls -triple
arm64e-apple-ios -DNO_BLOCK_DESC_AUTH -emit-llvm -o - %s | FileCheck %s
--check-prefix=NODESCRIPTORAUTH
+#ifndef NO_BLOCK_DESC_AUTH
_Static_assert(__has_feature(ptrauth_signed_block_descriptors),
"-fptrauth-block-descriptor-pointers should set
ptrauth_signed_block_descriptors");
+#else
+_Static_assert(!__has_feature(ptrauth_signed_block_descriptors),
"-fptrauth-block-descriptor-pointers should not be enabled by default");
+#endif
void a() {
// Test out a global block.
@@ -8,9 +13,11 @@ void a() {
}
// CHECK: [[BLOCK_DESCRIPTOR_NAME:@"__block_descriptor_.*"]] = linkonce_odr
hidden unnamed_addr constant { i64, i64, ptr, ptr } { i64 0, i64 32, ptr @.str,
ptr null }
+// CHECK: @__block_literal_global = internal constant { ptr, i32, i32, ptr,
ptr } { ptr @_NSConcreteGlobalBlock, i32 1342177280, i32 0, ptr ptrauth (ptr
@__a_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({ ptr, i32, i32,
ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr ptrauth (ptr
[[BLOCK_DESCRIPTOR_NAME]], i32 2, i64 49339, ptr getelementptr inbounds ({ ptr,
i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 4)) }
+// NODESCRIPTORAUTH: [[BLOCK_DESCRIPTOR_NAME:@"__block_descriptor_.*"]] =
linkonce_odr hidden unnamed_addr constant { i64, i64, ptr, ptr } { i64 0, i64
32, ptr @.str, ptr null }
+// NODESCRIPTORAUTH: @__block_literal_global = internal constant { ptr, i32,
i32, ptr, ptr } { ptr @_NSConcreteGlobalBlock, i32 1342177280, i32 0, ptr
ptrauth (ptr @__a_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({
ptr, i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr
[[BLOCK_DESCRIPTOR_NAME]] }
-// CHECK: @__block_literal_global = internal constant { ptr, i32, i32, ptr,
ptr } { ptr @_NSConcreteGlobalBlock, i32 1342177280, i32 0, ptr ptrauth (ptr
@__a_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({ ptr, i32, i32,
ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr ptrauth (ptr
@"__block_descriptor_32_e5_v8\01?0l", i32 2, i64 49339, ptr getelementptr
inbounds ({ ptr, i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32
4)) }
void b(int p) {
// CHECK-LABEL: define void @b
@@ -25,4 +32,8 @@ void b(int p) {
// CHECK: [[SIGNED_REF:%.*]] = call i64 @llvm.ptrauth.sign(i64 ptrtoint (ptr
@"__block_descriptor_36_e5_v8\01?0l" to i64), i32 2, i64 [[BLENDED]])
// CHECK: [[SIGNED_REF_PTR:%.*]] = inttoptr i64 [[SIGNED_REF]] to ptr
// CHECK: store ptr [[SIGNED_REF_PTR]], ptr [[BLOCK_DESCRIPTOR_REF]]
+
+ // NODESCRIPTORAUTH: [[BLOCK:%.*]] = alloca <{ ptr, i32, i32, ptr, ptr, i32
}>
+ // NODESCRIPTORAUTH: [[BLOCK_DESCRIPTOR_REF:%.*]] = getelementptr inbounds
nuw <{ {{.*}} }>, ptr [[BLOCK]], i32 0, i32 4
+ // NODESCRIPTORAUTH: store ptr @"__block_descriptor_36_e5_v8\01?0l", ptr
[[BLOCK_DESCRIPTOR_REF]]
}
diff --git a/clang/test/CodeGenObjC/ptrauth-block-isa.m
b/clang/test/CodeGenObjC/ptrauth-block-isa.m
index c37fe8b0d7fec..248e57769ba1e 100644
--- a/clang/test/CodeGenObjC/ptrauth-block-isa.m
+++ b/clang/test/CodeGenObjC/ptrauth-block-isa.m
@@ -2,7 +2,7 @@
void (^globalblock)(void) = ^{};
// CHECK: [[BLOCK_DESCRIPTOR_NAME:@"__block_descriptor_.*"]] = linkonce_odr
hidden unnamed_addr constant { i64, i64, ptr, ptr } { i64 0, i64 32, ptr @.str,
ptr null }, comdat, align 8
-// CHECK: @__block_literal_global = internal constant { ptr, i32, i32, ptr,
ptr } { ptr ptrauth (ptr @_NSConcreteGlobalBlock, i32 2, i64 27361, ptr
@__block_literal_global), i32 1342177280, i32 0, ptr ptrauth (ptr
@globalblock_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({ ptr,
i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr ptrauth
(ptr [[BLOCK_DESCRIPTOR_NAME]], i32 2, i64 49339, ptr getelementptr inbounds ({
ptr, i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 4)) }
+// CHECK: @__block_literal_global = internal constant { ptr, i32, i32, ptr,
ptr } { ptr ptrauth (ptr @_NSConcreteGlobalBlock, i32 2, i64 27361, ptr
@__block_literal_global), i32 1342177280, i32 0, ptr ptrauth (ptr
@globalblock_block_invoke, i32 0, i64 0, ptr getelementptr inbounds ({ ptr,
i32, i32, ptr, ptr }, ptr @__block_literal_global, i32 0, i32 3)), ptr
[[BLOCK_DESCRIPTOR_NAME]] }
@interface A
- (int) count;
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