Generate begin_access [signed] when handling a field function pointer with __ptrauth qualifier

Author: meg-gupta

lib/SILGen/SILGenLValue.cpp

@@ -853,8 +853,17 @@ namespace {
       // TODO: if the base is +1, break apart its cleanup.
       auto Res = SGF.B.createStructElementAddr(loc, base.getValue(),
                                                Field, SubstFieldType);
-      return ManagedValue::forLValue(Res);
+
+      if (!Field->getPointerAuthQualifier() ||
+          !SGF.getOptions().EnableImportPtrauthFieldFunctionPointers) {
+        return ManagedValue::forLValue(Res);
+      }
+      auto beginAccess =
+          enterAccessScope(SGF, loc, base, Res, getTypeData(), getAccessKind(),
+                           SILAccessEnforcement::Signed, takeActorIsolation());
+      return ManagedValue::forLValue(beginAccess);
     }
+
     void dump(raw_ostream &OS, unsigned indent) const override {
       OS.indent(indent) << "StructElementComponent("
                         << Field->getName() << ")\n";

test/SILGen/Inputs/module.map

@@ -0,0 +1,3 @@
+module PointerAuth {
+   header "ptrauth_field_fptr_import.h"
+ }

test/SILGen/Inputs/ptrauth_field_fptr_import.h

@@ -0,0 +1,10 @@
+#ifndef TEST_C_FUNCTION
+#define TEST_C_FUNCTION
+
+struct SecureStruct {
+  int (*__ptrauth(2, 0, 88)(secure_func_ptr1))();
+  int (*__ptrauth(3, 0, 66)(secure_func_ptr2))();
+};
+
+struct SecureStruct *ptr_to_secure_struct;
+#endif

test/SILGen/ptrauth_field_fptr_import.swift

@@ -0,0 +1,49 @@
+// RUN: %swift-frontend %s -enable-import-ptrauth-field-function-pointers -emit-silgen -target arm64e-apple-ios13.0 -I %S/Inputs/ 2>&1 | %FileCheck %s
+// REQUIRES: CPU=arm64e
+// REQUIRES: OS=ios
+
+import PointerAuth
+
+// CHECK-LABEL: sil hidden [ossa] @$s25ptrauth_field_fptr_import05test_B8_fn_reads5Int32VyF :
+// CHECK: [[GLOB:%.*]] = global_addr @ptr_to_secure_struct : $*Optional<UnsafeMutablePointer<SecureStruct>>
+// CHECK: [[A1:%.*]] = begin_access [read] [dynamic] [[GLOB]] : $*Optional<UnsafeMutablePointer<SecureStruct>>
+// CHECK: [[LD1:%.*]] = load [trivial] [[A1]] : $*Optional<UnsafeMutablePointer<SecureStruct>>
+// CHECK: end_access [[A1]] : $*Optional<UnsafeMutablePointer<SecureStruct>>
+// CHECK: switch_enum [[LD1]] : $Optional<UnsafeMutablePointer<SecureStruct>>, case #Optional.some!enumelt: bb2, case #Optional.none!enumelt: bb1
+// CHECK: bb2([[BBARG1:%.*]] : $UnsafeMutablePointer<SecureStruct>):
+// CHECK: [[F1:%.*]] = function_ref @$sSp7pointeexvlu : $@convention(method) <τ_0_0> (UnsafeMutablePointer<τ_0_0>) -> UnsafePointer<τ_0_0>
+// CHECK: [[PTR1:%.*]] = apply [[F1]]<SecureStruct>([[BBARG1]]) : $@convention(method) <τ_0_0> (UnsafeMutablePointer<τ_0_0>) -> UnsafePointer<τ_0_0>
+// CHECK: [[RAW1:%.*]] = struct_extract [[PTR1]] : $UnsafePointer<SecureStruct>, #UnsafePointer._rawValue
+// CHECK: [[ADDR1:%.*]] = pointer_to_address [[RAW1]] : $Builtin.RawPointer to [strict] $*SecureStruct
+// CHECK: [[A2:%.*]] = begin_access [read] [unsafe] [[ADDR1]] : $*SecureStruct
+// CHECK: [[ELEM1:%.*]] = struct_element_addr [[A2]] : $*SecureStruct, #SecureStruct.secure_func_ptr1
+// CHECK: [[ASIGNED:%.*]] = begin_access [read] [signed] [[ELEM1]] : $*Optional<@convention(c) () -> Int32>
+// CHECK: [[FPLOAD:%.*]] = load [trivial] [[ASIGNED]] : $*Optional<@convention(c) () -> Int32>
+// CHECK: end_access [[ASIGNED]] : $*Optional<@convention(c) () -> Int32>
+// CHECK: end_access [[A2]] : $*SecureStruct
+// CHECK: switch_enum [[FPLOAD]] : $Optional<@convention(c) () -> Int32>, case #Optional.some!enumelt: bb4, case #Optional.none!enumelt: bb3
+// CHECK-LABEL: } // end sil function '$s25ptrauth_field_fptr_import05test_B8_fn_reads5Int32VyF'
+func test_field_fn_read() -> Int32 {
+  let fn = ptr_to_secure_struct!.pointee.secure_func_ptr1!
+  return fn()
+}
+
+// CHECK-LABEL: sil hidden [ossa] @$s25ptrauth_field_fptr_import05test_B12_fn_ptr_swapyyF :
+// CHECK:bb8([[UMP:%.*]] : $UnsafeMutablePointer<SecureStruct>):
+// CHECK:  [[F1:%.*]] = function_ref @$sSp7pointeexvau : $@convention(method) <τ_0_0> (UnsafeMutablePointer<τ_0_0>) -> UnsafeMutablePointer<τ_0_0>
+// CHECK:  [[P:%.*]] = apply [[F1]]<SecureStruct>([[UMP]]) : $@convention(method) <τ_0_0> (UnsafeMutablePointer<τ_0_0>) -> UnsafeMutablePointer<τ_0_0>
+// CHECK:  [[EX1:%.*]] = struct_extract [[P]] : $UnsafeMutablePointer<SecureStruct>, #UnsafeMutablePointer._rawValue
+// CHECK:  [[ADDR:%.*]] = pointer_to_address [[EX1]] : $Builtin.RawPointer to [strict] $*SecureStruct
+// CHECK:  [[A1:%.*]] = begin_access [modify] [unsafe] [[ADDR]] : $*SecureStruct
+// CHECK:  [[ELEM1:%.*]] = struct_element_addr [[A1]] : $*SecureStruct, #SecureStruct.secure_func_ptr2
+// CHECK:  [[A2:%.*]] = begin_access [modify] [signed] [[ELEM1]] : $*Optional<@convention(c) () -> Int32>
+// CHECK:  assign {{.*}} to [[A2]] : $*Optional<@convention(c) () -> Int32>
+// CHECK:  end_access [[A2]] : $*Optional<@convention(c) () -> Int32>
+// CHECK:  end_access [[A1]] : $*SecureStruct
+// CHECK-LABEL: } // end sil function '$s25ptrauth_field_fptr_import05test_B12_fn_ptr_swapyyF'
+func test_field_fn_ptr_swap() {
+  let t = ptr_to_secure_struct!.pointee.secure_func_ptr1
+  ptr_to_secure_struct!.pointee.secure_func_ptr1 = ptr_to_secure_struct!.pointee.secure_func_ptr2
+  ptr_to_secure_struct!.pointee.secure_func_ptr2 = t
+}
+