[clang] [clang][ptrauth] Warn about the use of a weak signing schema (PR #157779)

[Daniil Kovalev via cfe-commits]

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@@ -0,0 +1,60 @@
+// RUN: %clang_cc1 -triple arm64e-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -Wno-unused-variable -verify %s
+// RUN: %clang_cc1 -triple arm64e-apple-ios -DNO_PTRAUTH -fsyntax-only -Wno-unused-variable -verify=noptrauth %s
+
+// noptrauth-no-diagnostics
+
+#include <ptrauth.h>
+
+#if defined(__PTRAUTH__) == defined(NO_PTRAUTH)
+#error expected pointer authentication state does not match actual
+#endif
+
+#if defined(NO_PTRAUTH)
+#define FN_PTR_AUTH(address_diversity, constant_discriminator)
+#else
+#define FN_PTR_AUTH(address_diversity, constant_discriminator) \
+  __ptrauth(ptrauth_key_function_pointer, address_diversity, constant_discriminator)
+#endif
+
+// Global variables with external linkage and weak pointer authentication should
+// not raise any warning.
+extern void(* g1_external_weak)(void);
+void(* FN_PTR_AUTH(0, 0) g2_external_weak)(void);
+
+// Global variables with internal linkage and strong pointer authentication
+// should not raise any warning.
+static void(* FN_PTR_AUTH(1, 65535) g1_internal_strong)(void);
+static void(* FN_PTR_AUTH(0, 65535) g2_internal_strong)(void);
+static void(* FN_PTR_AUTH(1, 0) g3_internal_strong)(void);
+
+#if !defined(NO_PTRAUTH)
+// Global variables with internal linkage and weak pointer authentication should
+// raise a warning.
+static void(* g1_internal_weak)(void);
+// expected-warning at -1 {{'g1_internal_weak' has internal linkage with a default pointer authentication schema that should be overridden by an explicit schema with unique diversifiers}}
+static void(* FN_PTR_AUTH(0, 0) g2_internal_weak)(void);
+// expected-warning at -1 {{'g2_internal_weak' has internal linkage with a pointer authentication schema that should be overridden by a schema with unique diversifiers}}
+
+// Assert that -Wptrauth-weak-schema silences warnings.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wptrauth-weak-schema"
+static void(* g3_internal_weak)(void);
+#pragma clang diagnostic pop
+#endif
+
+void test_local_variables(void) {
+    #if !defined(NO_PTRAUTH)
+    // Local variables (internal linkage) with weak pointer authentication
+    // should raise a warning.
+    static void(* l1_internal_weak)(void);
+    // expected-warning at -1 {{'l1_internal_weak' has internal linkage with a default pointer authentication schema that should be overridden by an explicit schema with unique diversifiers}}
+    static void(* FN_PTR_AUTH(0, 0) l2_internal_weak)(void);
+    // expected-warning at -1 {{'l2_internal_weak' has internal linkage with a pointer authentication schema that should be overridden by a schema with unique diversifiers}}
+    #endif
+
+    // Local variables (internal linkage) with strong pointer authentication
+    // should not raise any warning.
+    void(* FN_PTR_AUTH(1, 65535) l1_internal_strong)(void);
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kovdan01 wrote:

`l{1|2}_internal_weak` has static storage duration, while `l{1|2|3}_internal_strong` has scoped storage duration. Is this intended?

https://github.com/llvm/llvm-project/pull/157779