https://github.com/martinuy updated https://github.com/llvm/llvm-project/pull/157779
>From 8fe991fb658d02351b2e819b275de1e821075f03 Mon Sep 17 00:00:00 2001 From: Martin Balao Alonso <[email protected]> Date: Tue, 9 Sep 2025 18:29:38 -0700 Subject: [PATCH 1/3] [clang][ptrauth] Warn about the use of a weak signing schema In this change we added the -Wptrauth-weak-schema diagnostic (enabled by default on targets that support pointer authentication) to warn about the use of a weak signing schema for function pointers stored in global variables with internal linkage. rdar://159299739 --- clang/include/clang/Basic/DiagnosticGroups.td | 1 + .../clang/Basic/DiagnosticSemaKinds.td | 4 ++ clang/lib/Sema/SemaDecl.cpp | 9 +++ clang/test/Sema/ptrauth-weak-schema.c | 68 +++++++++++++++++++ 4 files changed, 82 insertions(+) create mode 100644 clang/test/Sema/ptrauth-weak-schema.c diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td index 0c994e0b5ca4d..de10c39a4ac3c 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -1072,6 +1072,7 @@ def GNUZeroLineDirective : DiagGroup<"gnu-zero-line-directive">; def GNUZeroVariadicMacroArguments : DiagGroup<"gnu-zero-variadic-macro-arguments", [VariadicMacroArgumentsOmitted]>; def MisleadingIndentation : DiagGroup<"misleading-indentation">; def PtrAuthNullPointers : DiagGroup<"ptrauth-null-pointers">; +def PtrAuthWeakSchema : DiagGroup<"ptrauth-weak-schema">; // This covers both the deprecated case (in C++98) // and the extension case (in C++11 onwards). diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index b0e669cd3560d..e1dc8ab20d6f4 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -1046,6 +1046,10 @@ def err_ptrauth_address_discrimination_invalid : Error< def err_ptrauth_extra_discriminator_invalid : Error< "invalid extra discriminator flag '%0'; '__ptrauth' requires a value between " "'0' and '%1'">; +def warn_ptrauth_weak_schema + : Warning<"internal variable %0 is using a weak signing schema for pointer " + "authentication">, + InGroup<PtrAuthWeakSchema>; /// main() // static main() is not an error in C, just in C++. diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index 7c1459e320167..a8eb1188916b7 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -8357,6 +8357,15 @@ NamedDecl *Sema::ActOnVariableDeclarator( D.isFunctionDefinition()); } + // Warn about the use of a weak pointer authentication schema on a variable + // with internal linkage. + if (getLangOpts().PointerAuthCalls && NewVD->isFunctionPointerType() && + !isExternallyVisible(NewVD->getLinkageInternal())) { + PointerAuthQualifier Q = NewVD->getType().getQualifiers().getPointerAuth(); + if (!Q || (!Q.isAddressDiscriminated() && Q.getExtraDiscriminator() == 0)) + Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema) << NewVD; + } + if (NewTemplate) { if (NewVD->isInvalidDecl()) NewTemplate->setInvalidDecl(); diff --git a/clang/test/Sema/ptrauth-weak-schema.c b/clang/test/Sema/ptrauth-weak-schema.c new file mode 100644 index 0000000000000..792ff9f99627c --- /dev/null +++ b/clang/test/Sema/ptrauth-weak-schema.c @@ -0,0 +1,68 @@ +// RUN: %clang_cc1 -triple arm64e-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify %s +// RUN: %clang_cc1 -triple arm64e-apple-ios -DNO_PTRAUTH -fsyntax-only -verify %s + +#if defined(NO_PTRAUTH) + +#define FN_PTR_AUTH(address_diversity, constant_discriminator) +// expected-no-diagnostics + +#else // !defined(NO_PTRAUTH) + +#if !__has_extension(ptrauth_qualifier) +#error __ptrauth qualifier not enabled +#endif + +#include <ptrauth.h> + +#define FN_PTR_AUTH(address_diversity, constant_discriminator) \ + __ptrauth(ptrauth_key_function_pointer, address_diversity, constant_discriminator) + +#endif // defined(NO_PTRAUTH) + +// 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@-1 {{internal variable 'g1_internal_weak' is using a weak signing schema for pointer authentication}} +static void(* FN_PTR_AUTH(0, 0) g2_internal_weak)(void); +// expected-warning@-1 {{internal variable 'g2_internal_weak' is using a weak signing schema for pointer authentication}} + +// 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) { + #pragma clang diagnostic push + #pragma clang diagnostic ignored "-Wunused-variable" + + #if !defined(NO_PTRAUTH) + // Local variables (internal linkage) with weak pointer authentication + // should raise a warning. + static void(* l1_internal_weak)(void); + // expected-warning@-1 {{internal variable 'l1_internal_weak' is using a weak signing schema for pointer authentication}} + static void(* FN_PTR_AUTH(0, 0) l2_internal_weak)(void); + // expected-warning@-1 {{internal variable 'l2_internal_weak' is using a weak signing schema for pointer authentication}} + #endif + + // Local variables (internal linkage) with strong pointer authentication + // should not raise any warning. + void(* FN_PTR_AUTH(1, 65535) l1_internal_strong)(void); + void(* FN_PTR_AUTH(0, 65535) l2_internal_strong)(void); + void(* FN_PTR_AUTH(1, 0) l3_internal_strong)(void); + + #pragma clang diagnostic pop +} >From bc4d0a78e74b86b2ae490d8b7a3428a65fa66ece Mon Sep 17 00:00:00 2001 From: Martin Balao Alonso <[email protected]> Date: Wed, 10 Sep 2025 16:10:29 -0700 Subject: [PATCH 2/3] Changes after @ojhunt's review on 2025-09-09 (#157779) --- clang/include/clang/AST/ASTContext.h | 9 ++--- clang/include/clang/Basic/DiagnosticGroups.td | 1 - .../clang/Basic/DiagnosticSemaKinds.td | 7 ++-- clang/lib/Sema/SemaDecl.cpp | 10 +++--- clang/test/Sema/ptrauth-weak-schema.c | 34 ++++++------------- 5 files changed, 26 insertions(+), 35 deletions(-) diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h index 1c17333b722f8..1580968e857d7 100644 --- a/clang/include/clang/AST/ASTContext.h +++ b/clang/include/clang/AST/ASTContext.h @@ -659,6 +659,11 @@ class ASTContext : public RefCountedBase<ASTContext> { return findPointerAuthContent(T) != PointerAuthContent::None; } + // A simple helper function to short circuit pointer auth checks. + bool isPointerAuthenticationAvailable() const { + return LangOpts.PointerAuthCalls || LangOpts.PointerAuthIntrinsics; + } + private: llvm::DenseMap<const CXXRecordDecl *, CXXRecordDeclRelocationInfo> RelocatableClasses; @@ -670,10 +675,6 @@ class ASTContext : public RefCountedBase<ASTContext> { AddressDiscriminatedData }; - // A simple helper function to short circuit pointer auth checks. - bool isPointerAuthenticationAvailable() const { - return LangOpts.PointerAuthCalls || LangOpts.PointerAuthIntrinsics; - } PointerAuthContent findPointerAuthContent(QualType T) const; mutable llvm::DenseMap<const RecordDecl *, PointerAuthContent> RecordContainsAddressDiscriminatedPointerAuth; diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td index de10c39a4ac3c..0c994e0b5ca4d 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -1072,7 +1072,6 @@ def GNUZeroLineDirective : DiagGroup<"gnu-zero-line-directive">; def GNUZeroVariadicMacroArguments : DiagGroup<"gnu-zero-variadic-macro-arguments", [VariadicMacroArgumentsOmitted]>; def MisleadingIndentation : DiagGroup<"misleading-indentation">; def PtrAuthNullPointers : DiagGroup<"ptrauth-null-pointers">; -def PtrAuthWeakSchema : DiagGroup<"ptrauth-weak-schema">; // This covers both the deprecated case (in C++98) // and the extension case (in C++11 onwards). diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index e1dc8ab20d6f4..35bedc9349686 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -1047,9 +1047,10 @@ def err_ptrauth_extra_discriminator_invalid : Error< "invalid extra discriminator flag '%0'; '__ptrauth' requires a value between " "'0' and '%1'">; def warn_ptrauth_weak_schema - : Warning<"internal variable %0 is using a weak signing schema for pointer " - "authentication">, - InGroup<PtrAuthWeakSchema>; + : Warning<"%0 has internal linkage with a %select{|default }1" + "pointer authentication schema that should be overridden by " + "%select{a|an explicit}1 schema with unique diversifiers">, + InGroup<DiagGroup<"ptrauth-weak-schema">>; /// main() // static main() is not an error in C, just in C++. diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index a8eb1188916b7..7a7abf1c4b627 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -8359,11 +8359,13 @@ NamedDecl *Sema::ActOnVariableDeclarator( // Warn about the use of a weak pointer authentication schema on a variable // with internal linkage. - if (getLangOpts().PointerAuthCalls && NewVD->isFunctionPointerType() && - !isExternallyVisible(NewVD->getLinkageInternal())) { + if (Context.isPointerAuthenticationAvailable() && + NewVD->isFunctionPointerType() && !NewVD->isExternallyVisible()) { PointerAuthQualifier Q = NewVD->getType().getQualifiers().getPointerAuth(); - if (!Q || (!Q.isAddressDiscriminated() && Q.getExtraDiscriminator() == 0)) - Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema) << NewVD; + if (!Q || (!Q.isAddressDiscriminated() && Q.getExtraDiscriminator() == 0)) { + Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema) + << NewVD << (Q ? 0 : 1); + } } if (NewTemplate) { diff --git a/clang/test/Sema/ptrauth-weak-schema.c b/clang/test/Sema/ptrauth-weak-schema.c index 792ff9f99627c..e0aa89efc47ab 100644 --- a/clang/test/Sema/ptrauth-weak-schema.c +++ b/clang/test/Sema/ptrauth-weak-schema.c @@ -1,23 +1,16 @@ -// RUN: %clang_cc1 -triple arm64e-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify %s -// RUN: %clang_cc1 -triple arm64e-apple-ios -DNO_PTRAUTH -fsyntax-only -verify %s +// 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 -#if defined(NO_PTRAUTH) - -#define FN_PTR_AUTH(address_diversity, constant_discriminator) -// expected-no-diagnostics - -#else // !defined(NO_PTRAUTH) - -#if !__has_extension(ptrauth_qualifier) -#error __ptrauth qualifier not enabled -#endif +// noptrauth-no-diagnostics #include <ptrauth.h> +#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 // defined(NO_PTRAUTH) +#endif // Global variables with external linkage and weak pointer authentication should // not raise any warning. @@ -34,9 +27,9 @@ static void(* FN_PTR_AUTH(1, 0) g3_internal_strong)(void); // Global variables with internal linkage and weak pointer authentication should // raise a warning. static void(* g1_internal_weak)(void); -// expected-warning@-1 {{internal variable 'g1_internal_weak' is using a weak signing schema for pointer authentication}} +// expected-warning@-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@-1 {{internal variable 'g2_internal_weak' is using a weak signing schema for pointer authentication}} +// expected-warning@-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 @@ -46,16 +39,13 @@ static void(* g3_internal_weak)(void); #endif void test_local_variables(void) { - #pragma clang diagnostic push - #pragma clang diagnostic ignored "-Wunused-variable" - #if !defined(NO_PTRAUTH) // Local variables (internal linkage) with weak pointer authentication // should raise a warning. static void(* l1_internal_weak)(void); - // expected-warning@-1 {{internal variable 'l1_internal_weak' is using a weak signing schema for pointer authentication}} + // expected-warning@-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@-1 {{internal variable 'l2_internal_weak' is using a weak signing schema for pointer authentication}} + // expected-warning@-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 @@ -63,6 +53,4 @@ void test_local_variables(void) { void(* FN_PTR_AUTH(1, 65535) l1_internal_strong)(void); void(* FN_PTR_AUTH(0, 65535) l2_internal_strong)(void); void(* FN_PTR_AUTH(1, 0) l3_internal_strong)(void); - - #pragma clang diagnostic pop } >From 1d90050dce1de92876d1f9a4be62acf7090c7483 Mon Sep 17 00:00:00 2001 From: Martin Balao Alonso <[email protected]> Date: Wed, 10 Sep 2025 19:22:29 -0700 Subject: [PATCH 3/3] fixup! Changes after @ojhunt's review on 2025-09-09 (#157779) Changes after @ojhunt's review on 2025-09-10 (#157779) --- clang/lib/Sema/SemaDecl.cpp | 3 +-- clang/test/Sema/ptrauth-weak-schema.c | 4 ++++ 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index 7a7abf1c4b627..60410c05d10cb 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -8363,8 +8363,7 @@ NamedDecl *Sema::ActOnVariableDeclarator( NewVD->isFunctionPointerType() && !NewVD->isExternallyVisible()) { PointerAuthQualifier Q = NewVD->getType().getQualifiers().getPointerAuth(); if (!Q || (!Q.isAddressDiscriminated() && Q.getExtraDiscriminator() == 0)) { - Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema) - << NewVD << (Q ? 0 : 1); + Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema) << NewVD << !Q; } } diff --git a/clang/test/Sema/ptrauth-weak-schema.c b/clang/test/Sema/ptrauth-weak-schema.c index e0aa89efc47ab..f7f10be07736e 100644 --- a/clang/test/Sema/ptrauth-weak-schema.c +++ b/clang/test/Sema/ptrauth-weak-schema.c @@ -5,6 +5,10 @@ #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 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
