[clang][Obj-C][PAC] Make block descriptor pointer signing configurable

clang/include/clang/Basic/Features.def

@@ -155,7 +155,7 @@ 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)

clang/include/clang/Basic/LangOptions.def

@@ -136,6 +136,8 @@ 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")
 

clang/include/clang/Driver/Options.td

@@ -4546,6 +4546,7 @@ 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>,

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 =

clang/test/CodeGenObjC/ptrauth-block-descriptor-pointer.m

@@ -1,16 +1,23 @@
-// 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.
   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_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]]
 }

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;