[PATCH] rust: fwctl: declare cfi_encoding for fwctl_rpc_scope

[Alice Ryhl <aliceryhl@google.com>]

Currently, VTable::fw_rpc_callback() takes scope as a u32, whereas C
calls fwctl_ops::fw_rpc with enum fwctl_rpc_scope. With kCFI enabled,
enum types are encoded distinctly from integers, causing every fw_rpc
indirect call into a Rust fwctl driver to trip a CFI failure. Thus,
generate fwctl_rpc_scope as a newtype with a cfi_encoding attribute and
use it in fw_rpc_callback().

Cc: stable@vger.kernel.org
Fixes: e052daab94ee ("rust: introduce abstractions for fwctl")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/bindgen_parameters |  2 ++
 rust/kernel/fwctl.rs    | 12 ++++++------
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/rust/bindgen_parameters b/rust/bindgen_parameters
index 8402b0c93545..e4f8c07743a8 100644
--- a/rust/bindgen_parameters
+++ b/rust/bindgen_parameters
@@ -27,6 +27,8 @@
 --opaque-type spinlock
 
 # enums that appear in indirect function calls should specify a cfi type
+--newtype-enum fwctl_rpc_scope
+--with-attribute-custom-enum=fwctl_rpc_scope='#[cfi_encoding="15fwctl_rpc_scope"]'
 --newtype-enum lru_status
 --with-attribute-custom-enum=lru_status='#[cfi_encoding="10lru_status"]'
 
diff --git a/rust/kernel/fwctl.rs b/rust/kernel/fwctl.rs
index f29244fb0d1d..b7778e4d5ee0 100644
--- a/rust/kernel/fwctl.rs
+++ b/rust/kernel/fwctl.rs
@@ -53,13 +53,13 @@ pub enum DeviceType {
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum RpcScope {
     /// Read/write access to device configuration.
-    Configuration = bindings::fwctl_rpc_scope_FWCTL_RPC_CONFIGURATION,
+    Configuration = bindings::fwctl_rpc_scope::FWCTL_RPC_CONFIGURATION.0,
     /// Read-only access to debug information.
-    DebugReadOnly = bindings::fwctl_rpc_scope_FWCTL_RPC_DEBUG_READ_ONLY,
+    DebugReadOnly = bindings::fwctl_rpc_scope::FWCTL_RPC_DEBUG_READ_ONLY.0,
     /// Write access to lockdown-compatible debug information.
-    DebugWrite = bindings::fwctl_rpc_scope_FWCTL_RPC_DEBUG_WRITE,
+    DebugWrite = bindings::fwctl_rpc_scope::FWCTL_RPC_DEBUG_WRITE.0,
     /// Full read/write access to all debug information (requires `CAP_SYS_RAWIO`).
-    DebugWriteFull = bindings::fwctl_rpc_scope_FWCTL_RPC_DEBUG_WRITE_FULL,
+    DebugWriteFull = bindings::fwctl_rpc_scope::FWCTL_RPC_DEBUG_WRITE_FULL.0,
 }
 
 impl TryFrom<u32> for RpcScope {
@@ -539,12 +539,12 @@ impl<T: Operations> VTable<T> {
     /// - `out_len` must be valid for reading and writing an initialised `usize`.
     unsafe extern "C" fn fw_rpc_callback(
         uctx: *mut bindings::fwctl_uctx,
-        scope: u32,
+        scope: bindings::fwctl_rpc_scope,
         rpc_in: *mut ffi::c_void,
         in_len: usize,
         out_len: *mut usize,
     ) -> *mut ffi::c_void {
-        let scope = match RpcScope::try_from(scope) {
+        let scope = match RpcScope::try_from(scope.0) {
             Ok(s) => s,
             Err(e) => return Error::to_ptr(e),
         };

---
base-commit: c03c1a14507dfaf8b856c2608f9ac216021fc222
change-id: 20261020-fwctl-cfi-encoding-70766ce0a03a

Best regards,
-- 
Alice Ryhl <aliceryhl@google.com>