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authorAlice Ryhl <aliceryhl@google.com>2024-08-29 08:22:45 +0000
committerMiguel Ojeda <ojeda@kernel.org>2024-09-13 00:03:14 +0200
commitd077242d68a31075ef5f5da041bf8f6fc19aa231 (patch)
tree58e375901c9edf51b8c1eaf1cc2a88a363e05fd3 /init
parent93dc3be19450447a3a7090bd1dfb9f3daac3e8d2 (diff)
rust: support for shadow call stack sanitizer
Add all of the flags that are needed to support the shadow call stack (SCS) sanitizer with Rust, and updates Kconfig to allow only configurations that work. The -Zfixed-x18 flag is required to use SCS on arm64, and requires rustc version 1.80.0 or greater. This restriction is reflected in Kconfig. When CONFIG_DYNAMIC_SCS is enabled, the build will be configured to include unwind tables in the build artifacts. Dynamic SCS uses the unwind tables at boot to find all places that need to be patched. The -Cforce-unwind-tables=y flag ensures that unwind tables are available for Rust code. In non-dynamic mode, the -Zsanitizer=shadow-call-stack flag is what enables the SCS sanitizer. Using this flag requires rustc version 1.82.0 or greater on the targets used by Rust in the kernel. This restriction is reflected in Kconfig. It is possible to avoid the requirement of rustc 1.80.0 by using -Ctarget-feature=+reserve-x18 instead of -Zfixed-x18. However, this flag emits a warning during the build, so this patch does not add support for using it and instead requires 1.80.0 or greater. The dependency is placed on `select HAVE_RUST` to avoid a situation where enabling Rust silently turns off the sanitizer. Instead, turning on the sanitizer results in Rust being disabled. We generally do not want changes to CONFIG_RUST to result in any mitigations being changed or turned off. At the time of writing, rustc 1.82.0 only exists via the nightly release channel. There is a chance that the -Zsanitizer=shadow-call-stack flag will end up needing 1.83.0 instead, but I think it is small. Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Kees Cook <kees@kernel.org> Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20240829-shadow-call-stack-v7-1-2f62a4432abf@google.com [ Fixed indentation using spaces. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig1
1 files changed, 0 insertions, 1 deletions
diff --git a/init/Kconfig b/init/Kconfig
index c6b744a48dcc..9bcda3b0a20f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1909,7 +1909,6 @@ config RUST
depends on !MODVERSIONS
depends on !GCC_PLUGIN_RANDSTRUCT
depends on !RANDSTRUCT
- depends on !SHADOW_CALL_STACK
depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
help
Enables Rust support in the kernel.