Add cross-language LLVM CFI support to the Rust compiler #105452

rcvalle · 2022-12-08T09:27:53Z

This PR adds cross-language LLVM Control Flow Integrity (CFI) support to the Rust compiler by adding the -Zsanitizer-cfi-normalize-integers option to be used with Clang -fsanitize-cfi-icall-normalize-integers for normalizing integer types (see https://reviews.llvm.org/D139395).

It provides 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). For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler, see design document in the tracking issue #89653.

Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and -Zsanitizer-cfi-normalize-integers, and requires proper (i.e., non-rustc) LTO (i.e., -Clinker-plugin-lto).

Thank you again, @bjorn3, @nikic, @samitolvanen, and the Rust community for all the help!

rustbot · 2022-12-08T09:28:06Z

r? @cjgillot

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compiler/rustc_middle/src/ty/sty.rs

bjorn3 · 2022-12-08T18:18:36Z

compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs

@@ -538,9 +514,31 @@ fn encode_ty<'tcx>(
        // User-defined types
        ty::Adt(adt_def, substs) => {


I believe this misses #[repr(transparent)] support.

Is it in transform_ty? How exactly does that function relate to encode_ty and why is it split?

Yes, it's handled in transform_ty, and its tests are here: https://github.com/rust-lang/rust/blob/master/src/test/codegen/sanitizer-cfi-emit-type-metadata-id-itanium-cxx-abi.rs#L116-L132. transform_ty coalesces types that have the same encoding into a single entity (e.g., c_void into unit), normalizes, and generalizes types before handing them to encode_ty. It greatly simplifies the encoding and compression/substitution logic.

cjgillot · 2022-12-10T07:41:11Z

r? @bjorn3

bors · 2022-12-16T13:10:41Z

☔ The latest upstream changes (presumably #105763) made this pull request unmergeable. Please resolve the merge conflicts.

Manishearth · 2023-05-03T22:43:36Z

@bors r=bjorn3

bors · 2023-05-03T22:43:38Z

📌 Commit 9a02f65 has been approved by bjorn3

It is now in the queue for this repository.

Add cross-language LLVM CFI support to the Rust compiler This PR adds cross-language LLVM Control Flow Integrity (CFI) support to the Rust compiler by adding the `-Zsanitizer-cfi-normalize-integers` option to be used with Clang `-fsanitize-cfi-icall-normalize-integers` for normalizing integer types (see https://reviews.llvm.org/D139395). It provides 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). For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler, see design document in the tracking issue rust-lang#89653. Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and -Zsanitizer-cfi-normalize-integers, and requires proper (i.e., non-rustc) LTO (i.e., -Clinker-plugin-lto). Thank you again, `@bjorn3,` `@nikic,` `@samitolvanen,` and the Rust community for all the help!

…earth Rollup of 10 pull requests Successful merges: - rust-lang#97594 (Implement tuple<->array convertions via `From`) - rust-lang#105452 (Add cross-language LLVM CFI support to the Rust compiler) - rust-lang#105695 (Replace generic thread parker with explicit no-op parker) - rust-lang#110371 (rustdoc: restructure type search engine to pick-and-use IDs) - rust-lang#110928 (tests: Add tests for LoongArch64) - rust-lang#110970 (tidy: remove ENTRY_LIMIT maximum checking and set it to 900) - rust-lang#111104 (Update ICU4X to 1.2) - rust-lang#111127 (Constify slice flatten method) - rust-lang#111146 (rustc_middle: Fix `opt_item_ident` for non-local def ids) - rust-lang#111154 (Use builtin FFX isolation for Fuchsia test runner) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

klensy · 2023-05-04T09:28:52Z

compiler/rustc_feature/src/active.rs

@@ -329,6 +329,8 @@ declare_features! (
    (active, cfg_target_thread_local, "1.7.0", Some(29594), None),
    /// Allow conditional compilation depending on rust version
    (active, cfg_version, "1.45.0", Some(64796), None),
+    /// Allows to use the `#[cfi_encoding = ""]` attribute.
+    (active, cfi_encoding, "1.69.0", Some(89653), None),


Should be CURRENT_RUSTC_VERSION?

…rrors fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang#105452 (comment)

fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang/rust#105452 (comment)

Add cross-language LLVM CFI support to the Rust compiler This PR adds cross-language LLVM Control Flow Integrity (CFI) support to the Rust compiler by adding the `-Zsanitizer-cfi-normalize-integers` option to be used with Clang `-fsanitize-cfi-icall-normalize-integers` for normalizing integer types (see https://reviews.llvm.org/D139395). It provides 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). For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler, see design document in the tracking issue rust-lang#89653. Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and -Zsanitizer-cfi-normalize-integers, and requires proper (i.e., non-rustc) LTO (i.e., -Clinker-plugin-lto). Thank you again, ``@bjorn3,`` ``@nikic,`` ``@samitolvanen,`` and the Rust community for all the help!

Fix rust-lang#115150 by encoding f32 and f64 correctly for cross-language CFI. I missed changing the encoding for f32 and f64 when I introduced the integer normalization option in rust-lang#105452 as integer normalization does not include floating point. `f32` and `f64` should be always encoded as `f` and `d` since they are both FFI safe when their representation are the same (i.e., IEEE 754) for both the Rust compiler and Clang.

…piler-errors Fix CFI: f32 and f64 are encoded incorrectly for cross-language CFI Fix rust-lang#115150 by encoding f32 and f64 correctly for cross-language CFI. I missed changing the encoding for f32 and f64 when I introduced the integer normalization option in rust-lang#105452 as integer normalization does not include floating point. `f32` and `f64` should be always encoded as `f` and `d` since they are both FFI safe when their representation are the same (i.e., IEEE 754) for both the Rust compiler and Clang.

Fix rust-lang#115150 by encoding f32 and f64 correctly for cross-language CFI. I missed changing the encoding for f32 and f64 when I introduced the integer normalization option in rust-lang#105452 as integer normalization does not include floating point. `f32` and `f64` should be always encoded as `f` and `d` since they are both FFI safe when their representation are the same (i.e., IEEE 754) for both the Rust compiler and Clang.

rustbot assigned cjgillot Dec 8, 2022

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 8, 2022

rcvalle mentioned this pull request Dec 8, 2022

Tracking Issue for LLVM Control Flow Integrity (CFI) Support for Rust #89653

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bjorn3 reviewed Dec 8, 2022

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rcvalle force-pushed the rust-cfi-3 branch 3 times, most recently from 8bc3f3d to de462bc Compare December 9, 2022 07:33

ojeda mentioned this pull request Dec 9, 2022

rustc wanted features & bugfixes Rust-for-Linux/linux#355

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rustbot assigned bjorn3 and unassigned cjgillot Dec 10, 2022

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rcvalle mentioned this pull request Dec 20, 2022

ICE: encode_const: unexpected type [usize; 1] with -Clto -Zsanitizer=cfi #100778

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bjorn3 added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 15, 2023

rcvalle mentioned this pull request Feb 13, 2023

RFC: Improve C types for cross-language LLVM CFI support rust-lang/rfcs#3296

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rcvalle force-pushed the rust-cfi-3 branch from 96f8a4a to e886874 Compare February 15, 2023 23:03

rcvalle force-pushed the rust-cfi-3 branch from 77b4492 to 9a02f65 Compare May 3, 2023 22:41

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels May 3, 2023

This was referenced May 3, 2023

Rollup of 11 pull requests #111165

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Rollup of 10 pull requests #111169

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bors merged commit 38bbc39 into rust-lang:master May 4, 2023

rustbot added this to the 1.71.0 milestone May 4, 2023

klensy reviewed May 4, 2023

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klensy mentioned this pull request May 15, 2023

fixup version placeholder for cfi_encoding feature #111605

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matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request May 15, 2023

Rollup merge of rust-lang#111605 - klensy:fixup_version, r=compiler-e…

a91f879

…rrors fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang#105452 (comment)

Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request May 16, 2023

Rollup merge of rust-lang#111605 - klensy:fixup_version, r=compiler-e…

d241adb

…rrors fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang#105452 (comment)

Noratrieb added a commit to Noratrieb/rust that referenced this pull request May 16, 2023

Rollup merge of rust-lang#111605 - klensy:fixup_version, r=compiler-e…

2573483

…rrors fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang#105452 (comment)

Noratrieb added a commit to Noratrieb/rust that referenced this pull request May 16, 2023

Rollup merge of rust-lang#111605 - klensy:fixup_version, r=compiler-e…

ecdf373

…rrors fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang#105452 (comment)

dtolnay mentioned this pull request May 16, 2023

Hide repr attribute from doc of types without guaranteed repr #107680

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RalfJung pushed a commit to RalfJung/miri that referenced this pull request May 18, 2023

Rollup merge of #111605 - klensy:fixup_version, r=compiler-errors

39260b4

fixup version placeholder for `cfi_encoding` feature Mentioned rust-lang/rust#105452 (comment)

This was referenced Aug 23, 2023

CFI: f32 and f64 are encoded incorrectly for cross-language CFI #115150

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Fix CFI: f32 and f64 are encoded incorrectly for cross-language CFI #115151

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rcvalle deleted the rust-cfi-3 branch April 22, 2024 23:06

workingjubilee mentioned this pull request Jul 10, 2025

LLVM CFI integration being undocumented complicates further codegen dev #143751

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daltenty mentioned this pull request Jul 29, 2025

[test] Correct llvm-component to tests that need x86 #144620

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		@@ -538,9 +514,31 @@ fn encode_ty<'tcx>(
		// User-defined types
		ty::Adt(adt_def, substs) => {

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