Auto merge of #95548 - rcvalle:rust-cfi-2, r=nagisa

Add fine-grained LLVM CFI support to the Rust compiler

This PR improves the LLVM Control Flow Integrity (CFI) support in the Rust compiler by providing forward-edge control flow protection for Rust-compiled code only by aggregating function pointers in groups identified by their return and parameter types.

Forward-edge control flow protection for C or C++ and Rust -compiled code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code share the same virtual address space) will be provided in later work as part of this project by identifying C char and integer type uses at the time types are encoded (see Type metadata in the design document in the tracking issue https://github.com/rust-lang/rust/issues/89653).

LLVM CFI can be enabled with -Zsanitizer=cfi and requires LTO (i.e., -Clto).

Thank you again, `@eddyb,` `@nagisa,` `@pcc,` and `@tmiasko` for all the help!

5 files changed, 19 insertions, 15 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 773c55cf551..3eee58d9d1c 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
 use rustc_middle::ty::{self, Instance, Ty, TypeVisitable};
 use rustc_span::source_map::Span;
 use rustc_span::{sym, Symbol};
-use rustc_symbol_mangling::typeid_for_fnabi;
+use rustc_symbol_mangling::typeid::typeid_for_fnabi;
 use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode};
 use rustc_target::abi::{self, HasDataLayout, WrappingRange};
 use rustc_target::spec::abi::Abi;
@@ -918,7 +918,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             // FIXME(rcvalle): Add support for generalized identifiers.
             // FIXME(rcvalle): Create distinct unnamed MDNodes for internal identifiers.
             let typeid = typeid_for_fnabi(bx.tcx(), fn_abi);
-            let typeid_metadata = bx.typeid_metadata(typeid);
+            let typeid_metadata = self.cx.typeid_metadata(typeid);
 
             // Test whether the function pointer is associated with the type identifier.
             let cond = bx.type_test(fn_ptr, typeid_metadata);
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index ec3f7a2156a..8ee375fa9e3 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -3,7 +3,6 @@ use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
 use rustc_middle::ty::{self, Instance, Ty, TypeFoldable, TypeVisitable};
-use rustc_symbol_mangling::typeid_for_fnabi;
 use rustc_target::abi::call::{FnAbi, PassMode};
 
 use std::iter;
@@ -247,13 +246,6 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     for (bb, _) in traversal::reverse_postorder(&mir) {
         fx.codegen_block(bb);
     }
-
-    // For backends that support CFI using type membership (i.e., testing whether a given  pointer
-    // is associated with a type identifier).
-    if cx.tcx().sess.is_sanitizer_cfi_enabled() {
-        let typeid = typeid_for_fnabi(cx.tcx(), fn_abi);
-        bx.type_metadata(llfn, typeid);
-    }
 }
 
 /// Produces, for each argument, a `Value` pointing at the
diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index 1bbe10141fc..9f49749bb41 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -160,8 +160,6 @@ pub trait BuilderMethods<'a, 'tcx>:
 
     fn range_metadata(&mut self, load: Self::Value, range: WrappingRange);
     fn nonnull_metadata(&mut self, load: Self::Value);
-    fn type_metadata(&mut self, function: Self::Function, typeid: String);
-    fn typeid_metadata(&mut self, typeid: String) -> Self::Value;
 
     fn store(&mut self, val: Self::Value, ptr: Self::Value, align: Align) -> Self::Value;
     fn store_with_flags(
diff --git a/compiler/rustc_codegen_ssa/src/traits/mod.rs b/compiler/rustc_codegen_ssa/src/traits/mod.rs
index 396768e0a42..782fdadbfb8 100644
--- a/compiler/rustc_codegen_ssa/src/traits/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/mod.rs
@@ -40,7 +40,8 @@ pub use self::intrinsic::IntrinsicCallMethods;
 pub use self::misc::MiscMethods;
 pub use self::statics::{StaticBuilderMethods, StaticMethods};
 pub use self::type_::{
-    ArgAbiMethods, BaseTypeMethods, DerivedTypeMethods, LayoutTypeMethods, TypeMethods,
+    ArgAbiMethods, BaseTypeMethods, DerivedTypeMethods, LayoutTypeMethods, TypeMembershipMethods,
+    TypeMethods,
 };
 pub use self::write::{ModuleBufferMethods, ThinBufferMethods, WriteBackendMethods};
 
diff --git a/compiler/rustc_codegen_ssa/src/traits/type_.rs b/compiler/rustc_codegen_ssa/src/traits/type_.rs
index 5d3f07317a3..8158e8dd011 100644
--- a/compiler/rustc_codegen_ssa/src/traits/type_.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/type_.rs
@@ -117,6 +117,13 @@ pub trait LayoutTypeMethods<'tcx>: Backend<'tcx> {
     ) -> Self::Type;
 }
 
+// For backends that support CFI using type membership (i.e., testing whether a given  pointer is
+// associated with a type identifier).
+pub trait TypeMembershipMethods<'tcx>: Backend<'tcx> {
+    fn set_type_metadata(&self, function: Self::Function, typeid: String);
+    fn typeid_metadata(&self, typeid: String) -> Self::Value;
+}
+
 pub trait ArgAbiMethods<'tcx>: HasCodegen<'tcx> {
     fn store_fn_arg(
         &mut self,
@@ -133,6 +140,12 @@ pub trait ArgAbiMethods<'tcx>: HasCodegen<'tcx> {
     fn arg_memory_ty(&self, arg_abi: &ArgAbi<'tcx, Ty<'tcx>>) -> Self::Type;
 }
 
-pub trait TypeMethods<'tcx>: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> {}
+pub trait TypeMethods<'tcx>:
+    DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> + TypeMembershipMethods<'tcx>
+{
+}
 
-impl<'tcx, T> TypeMethods<'tcx> for T where Self: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> {}
+impl<'tcx, T> TypeMethods<'tcx> for T where
+    Self: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> + TypeMembershipMethods<'tcx>
+{
+}