Added local_downcast function for binder native
Added a local_downcast function to be able to cast
a Binder Native object back to its base object.
WIth this change the cast of a Binder native object
will look like this:
// my_foo will be an Option<&MyFoo>
let my_foo = bn_foo.downcast_binder::<MyFoo>();
This change depends on changes to the AIDL compiler
to modify required lifetimes on the autogenerated
code.
Test: CI
Bug: 278780666
Change-Id: I00958df53bb9f052347992ada121d7febfc87dc5
diff --git a/libs/binder/rust/src/binder.rs b/libs/binder/rust/src/binder.rs
index a08cb7a..78f8877 100644
--- a/libs/binder/rust/src/binder.rs
+++ b/libs/binder/rust/src/binder.rs
@@ -21,6 +21,7 @@
use crate::proxy::{DeathRecipient, SpIBinder, WpIBinder};
use crate::sys;
+use downcast_rs::{impl_downcast, DowncastSync};
use std::borrow::Borrow;
use std::cmp::Ordering;
use std::convert::TryFrom;
@@ -51,7 +52,7 @@
/// interfaces) must implement this trait.
///
/// This is equivalent `IInterface` in C++.
-pub trait Interface: Send + Sync {
+pub trait Interface: Send + Sync + DowncastSync {
/// Convert this binder object into a generic [`SpIBinder`] reference.
fn as_binder(&self) -> SpIBinder {
panic!("This object was not a Binder object and cannot be converted into an SpIBinder.")
@@ -66,6 +67,8 @@
}
}
+impl_downcast!(sync Interface);
+
/// Implemented by sync interfaces to specify what the associated async interface is.
/// Generic to handle the fact that async interfaces are generic over a thread pool.
///
@@ -143,7 +146,7 @@
/// When using the AIDL backend, users need only implement the high-level AIDL-defined
/// interface. The AIDL compiler then generates a container struct that wraps
/// the user-defined service and implements `Remotable`.
-pub trait Remotable: Send + Sync {
+pub trait Remotable: Send + Sync + 'static {
/// The Binder interface descriptor string.
///
/// This string is a unique identifier for a Binder interface, and should be
@@ -893,6 +896,23 @@
$crate::binder_impl::IBinderInternal::set_requesting_sid(&mut binder, features.set_requesting_sid);
$crate::Strong::new(Box::new(binder))
}
+
+ /// Tries to downcast the interface to another type.
+ /// When receiving this object from a binder call, make sure that the object received is
+ /// a binder native object and that is of the right type for the Downcast:
+ ///
+ /// let binder = received_object.as_binder();
+ /// if !binder.is_remote() {
+ /// let binder_native: Binder<BnFoo> = binder.try_into()?;
+ /// let original_object = binder_native.downcast_binder::<MyFoo>();
+ /// // Check that returned type is not None before using it
+ /// }
+ ///
+ /// Handle the error cases instead of just calling `unwrap` or `expect` to prevent a
+ /// malicious caller to mount a Denial of Service attack.
+ pub fn downcast_binder<T: $interface>(&self) -> Option<&T> {
+ self.0.as_any().downcast_ref::<T>()
+ }
}
impl $crate::binder_impl::Remotable for $native {
@@ -1004,7 +1024,7 @@
$(
// Async interface trait implementations.
- impl<P: $crate::BinderAsyncPool> $crate::FromIBinder for dyn $async_interface<P> {
+ impl<P: $crate::BinderAsyncPool + 'static> $crate::FromIBinder for dyn $async_interface<P> {
fn try_from(mut ibinder: $crate::SpIBinder) -> std::result::Result<$crate::Strong<dyn $async_interface<P>>, $crate::StatusCode> {
use $crate::binder_impl::AssociateClass;
@@ -1030,27 +1050,27 @@
}
}
- impl<P: $crate::BinderAsyncPool> $crate::binder_impl::Serialize for dyn $async_interface<P> + '_ {
+ impl<P: $crate::BinderAsyncPool + 'static> $crate::binder_impl::Serialize for dyn $async_interface<P> + '_ {
fn serialize(&self, parcel: &mut $crate::binder_impl::BorrowedParcel<'_>) -> std::result::Result<(), $crate::StatusCode> {
let binder = $crate::Interface::as_binder(self);
parcel.write(&binder)
}
}
- impl<P: $crate::BinderAsyncPool> $crate::binder_impl::SerializeOption for dyn $async_interface<P> + '_ {
+ impl<P: $crate::BinderAsyncPool + 'static> $crate::binder_impl::SerializeOption for dyn $async_interface<P> + '_ {
fn serialize_option(this: Option<&Self>, parcel: &mut $crate::binder_impl::BorrowedParcel<'_>) -> std::result::Result<(), $crate::StatusCode> {
parcel.write(&this.map($crate::Interface::as_binder))
}
}
- impl<P: $crate::BinderAsyncPool> std::fmt::Debug for dyn $async_interface<P> + '_ {
+ impl<P: $crate::BinderAsyncPool + 'static> std::fmt::Debug for dyn $async_interface<P> + '_ {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.pad(stringify!($async_interface))
}
}
/// Convert a &dyn $async_interface to Strong<dyn $async_interface>
- impl<P: $crate::BinderAsyncPool> std::borrow::ToOwned for dyn $async_interface<P> {
+ impl<P: $crate::BinderAsyncPool + 'static> std::borrow::ToOwned for dyn $async_interface<P> {
type Owned = $crate::Strong<dyn $async_interface<P>>;
fn to_owned(&self) -> Self::Owned {
self.as_binder().into_interface()
@@ -1058,11 +1078,11 @@
}
}
- impl<P: $crate::BinderAsyncPool> $crate::binder_impl::ToAsyncInterface<P> for dyn $interface {
+ impl<P: $crate::BinderAsyncPool + 'static> $crate::binder_impl::ToAsyncInterface<P> for dyn $interface {
type Target = dyn $async_interface<P>;
}
- impl<P: $crate::BinderAsyncPool> $crate::binder_impl::ToSyncInterface for dyn $async_interface<P> {
+ impl<P: $crate::BinderAsyncPool + 'static> $crate::binder_impl::ToSyncInterface for dyn $async_interface<P> {
type Target = dyn $interface;
}
)?