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Auto merge of rust-lang#123071 - rcvalle:rust-cfi-fix-method-fn-ptr-c…
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…ast, r=compiler-errors

CFI: Fix methods as function pointer cast

Fix casting between methods and function pointers by assigning a secondary type id to methods with their concrete self so they can be used as function pointers.

This was split off from rust-lang#116404.

cc `@compiler-errors` `@workingjubilee`
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bors committed Mar 29, 2024
2 parents 1c19595 + 8e6b4e9 commit 58dcd1f
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Showing 5 changed files with 84 additions and 27 deletions.
52 changes: 26 additions & 26 deletions compiler/rustc_codegen_llvm/src/declare.rs
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,9 @@ use crate::llvm;
use crate::llvm::AttributePlace::Function;
use crate::type_::Type;
use crate::value::Value;
use itertools::Itertools;
use rustc_codegen_ssa::traits::TypeMembershipMethods;
use rustc_data_structures::fx::FxIndexSet;
use rustc_middle::ty::{Instance, Ty};
use rustc_symbol_mangling::typeid::{
kcfi_typeid_for_fnabi, kcfi_typeid_for_instance, typeid_for_fnabi, typeid_for_instance,
Expand Down Expand Up @@ -141,33 +143,31 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {

if self.tcx.sess.is_sanitizer_cfi_enabled() {
if let Some(instance) = instance {
let typeid = typeid_for_instance(self.tcx, instance, TypeIdOptions::empty());
self.set_type_metadata(llfn, typeid);
let typeid =
typeid_for_instance(self.tcx, instance, TypeIdOptions::GENERALIZE_POINTERS);
self.add_type_metadata(llfn, typeid);
let typeid =
typeid_for_instance(self.tcx, instance, TypeIdOptions::NORMALIZE_INTEGERS);
self.add_type_metadata(llfn, typeid);
let typeid = typeid_for_instance(
self.tcx,
instance,
TypeIdOptions::GENERALIZE_POINTERS | TypeIdOptions::NORMALIZE_INTEGERS,
);
self.add_type_metadata(llfn, typeid);
let mut typeids = FxIndexSet::default();
for options in [
TypeIdOptions::GENERALIZE_POINTERS,
TypeIdOptions::NORMALIZE_INTEGERS,
TypeIdOptions::NO_SELF_TYPE_ERASURE,
]
.into_iter()
.powerset()
.map(TypeIdOptions::from_iter)
{
let typeid = typeid_for_instance(self.tcx, instance, options);
if typeids.insert(typeid.clone()) {
self.add_type_metadata(llfn, typeid);
}
}
} else {
let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::empty());
self.set_type_metadata(llfn, typeid);
let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::GENERALIZE_POINTERS);
self.add_type_metadata(llfn, typeid);
let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::NORMALIZE_INTEGERS);
self.add_type_metadata(llfn, typeid);
let typeid = typeid_for_fnabi(
self.tcx,
fn_abi,
TypeIdOptions::GENERALIZE_POINTERS | TypeIdOptions::NORMALIZE_INTEGERS,
);
self.add_type_metadata(llfn, typeid);
for options in
[TypeIdOptions::GENERALIZE_POINTERS, TypeIdOptions::NORMALIZE_INTEGERS]
.into_iter()
.powerset()
.map(TypeIdOptions::from_iter)
{
let typeid = typeid_for_fnabi(self.tcx, fn_abi, options);
self.add_type_metadata(llfn, typeid);
}
}
}

Expand Down
11 changes: 11 additions & 0 deletions compiler/rustc_symbol_mangling/src/typeid.rs
Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,20 @@ bitflags! {
/// Options for typeid_for_fnabi.
#[derive(Clone, Copy, Debug)]
pub struct TypeIdOptions: u32 {
/// Generalizes pointers for compatibility with Clang
/// `-fsanitize-cfi-icall-generalize-pointers` option for cross-language LLVM CFI and KCFI
/// support.
const GENERALIZE_POINTERS = 1;
/// Generalizes repr(C) user-defined type for extern function types with the "C" calling
/// convention (or extern types) for cross-language LLVM CFI and KCFI support.
const GENERALIZE_REPR_C = 2;
/// Normalizes integers for compatibility with Clang
/// `-fsanitize-cfi-icall-experimental-normalize-integers` option for cross-language LLVM
/// CFI and KCFI support.
const NORMALIZE_INTEGERS = 4;
/// Do not perform self type erasure for attaching a secondary type id to methods with their
/// concrete self so they can be used as function pointers.
const NO_SELF_TYPE_ERASURE = 8;
}
}

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -1144,7 +1144,8 @@ pub fn typeid_for_instance<'tcx>(
instance.args = strip_receiver_auto(tcx, instance.args);
}

if let Some(impl_id) = tcx.impl_of_method(instance.def_id())
if !options.contains(EncodeTyOptions::NO_SELF_TYPE_ERASURE)
&& let Some(impl_id) = tcx.impl_of_method(instance.def_id())
&& let Some(trait_ref) = tcx.impl_trait_ref(impl_id)
{
let impl_method = tcx.associated_item(instance.def_id());
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
// Verifies that a secondary type metadata identifier is assigned to methods with their concrete
// self so they can be used as function pointers.
//
//@ needs-sanitizer-cfi
//@ compile-flags: -Clto -Cno-prepopulate-passes -Copt-level=0 -Zsanitizer=cfi -Ctarget-feature=-crt-static

#![crate_type="lib"]

trait Trait1 {
fn foo(&self);
}

struct Type1;

impl Trait1 for Type1 {
fn foo(&self) {}
// CHECK: define{{.*}}3foo{{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}}
}


// CHECK: ![[TYPE1]] = !{i64 0, !"_ZTSFvu3refIu3dynIu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}6Trait1u6regionEEE"}
// CHECK: ![[TYPE2]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}5Type1EE"}
23 changes: 23 additions & 0 deletions tests/ui/sanitizer/cfi-method-fn-ptr-cast.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
// Verifies that casting a method to a function pointer works.
//
// FIXME(#122848): Remove only-linux when fixed.
//@ only-linux
//@ needs-sanitizer-cfi
//@ compile-flags: -Clto -Copt-level=0 -Cprefer-dynamic=off -Ctarget-feature=-crt-static -Zsanitizer=cfi
//@ run-pass

trait Trait1 {
fn foo(&self);
}

struct Type1;

impl Trait1 for Type1 {
fn foo(&self) {}
}

fn main() {
let type1 = Type1 {};
let f = <Type1 as Trait1>::foo;
f(&type1);
}

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