https://github.com/ahmedbougacha created
https://github.com/llvm/llvm-project/pull/102416
We already ended up with -fptrauth-returns, the feature macro, the lang opt,
and the actual backend lowering.
The only part left is threading it all through PointerAuthOptions, to drive the
addition of the "ptrauth-returns" attribute to generated functions.
This also adds ptrauth_key_return_address to ptrauth.h.
>From 41061b347b7d0fa862f65896d4fc155cb0b791ba Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ah...@bougacha.org>
Date: Fri, 24 May 2024 20:24:26 -0700
Subject: [PATCH] [clang] Wire -fptrauth-returns to "ptrauth-returns" fn
attribute.
We already ended up with -fptrauth-returns, the feature macro, the lang
opt, and the actual backend lowering.
The only part left is threading it all through PointerAuthOptions, to
drive the addition of the "ptrauth-returns" attribute to generated
functions.
This also adds ptrauth_key_return_address to ptrauth.h.
---
clang/include/clang/Basic/PointerAuthOptions.h | 3 +++
clang/lib/CodeGen/CodeGenFunction.cpp | 2 ++
clang/lib/Frontend/CompilerInvocation.cpp | 4 +++-
clang/lib/Headers/ptrauth.h | 6 ++++++
4 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/clang/include/clang/Basic/PointerAuthOptions.h
b/clang/include/clang/Basic/PointerAuthOptions.h
index 8f63cf2ad2bf27..a847bf4a4b4f6d 100644
--- a/clang/include/clang/Basic/PointerAuthOptions.h
+++ b/clang/include/clang/Basic/PointerAuthOptions.h
@@ -163,6 +163,9 @@ class PointerAuthSchema {
};
struct PointerAuthOptions {
+ /// Should return addresses be authenticated?
+ bool ReturnAddresses = false;
+
/// Do indirect goto label addresses need to be authenticated?
bool IndirectGotos = false;
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp
b/clang/lib/CodeGen/CodeGenFunction.cpp
index af201554898f31..4dc57d0ff5b269 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -880,6 +880,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType
RetTy,
// Add pointer authentication attributes.
const CodeGenOptions &CodeGenOpts = CGM.getCodeGenOpts();
+ if (CodeGenOpts.PointerAuth.ReturnAddresses)
+ Fn->addFnAttr("ptrauth-returns");
if (CodeGenOpts.PointerAuth.FunctionPointers)
Fn->addFnAttr("ptrauth-calls");
if (CodeGenOpts.PointerAuth.IndirectGotos)
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp
b/clang/lib/Frontend/CompilerInvocation.cpp
index 225bd6416ce5fc..e206cfe4172616 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1511,13 +1511,15 @@ void CompilerInvocation::setDefaultPointerAuthOptions(
}
}
Opts.IndirectGotos = LangOpts.PointerAuthIndirectGotos;
+ Opts.ReturnAddresses = LangOpts.PointerAuthReturns;
}
static void parsePointerAuthOptions(PointerAuthOptions &Opts,
const LangOptions &LangOpts,
const llvm::Triple &Triple,
DiagnosticsEngine &Diags) {
- if (!LangOpts.PointerAuthCalls && !LangOpts.PointerAuthIndirectGotos)
+ if (!LangOpts.PointerAuthCalls && !LangOpts.PointerAuthIndirectGotos &&
+ !LangOpts.PointerAuthReturns)
return;
CompilerInvocation::setDefaultPointerAuthOptions(Opts, LangOpts, Triple);
diff --git a/clang/lib/Headers/ptrauth.h b/clang/lib/Headers/ptrauth.h
index 6cbdccff9a4c16..d489a67c533d41 100644
--- a/clang/lib/Headers/ptrauth.h
+++ b/clang/lib/Headers/ptrauth.h
@@ -28,6 +28,12 @@ typedef enum {
/* A process-specific key which can be used to sign data pointers. */
ptrauth_key_process_dependent_data = ptrauth_key_asdb,
+ /* The key used to sign return addresses on the stack.
+ The extra data is based on the storage address of the return address.
+ On AArch64, that is always the storage address of the return address + 8
+ (or, in other words, the value of the stack pointer on function entry) */
+ ptrauth_key_return_address = ptrauth_key_process_dependent_code,
+
/* The key used to sign C function pointers.
The extra data is always 0. */
ptrauth_key_function_pointer = ptrauth_key_process_independent_code,
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