On Tue, 10 Dec 2024, Alice Ryhl wrote:
> This allows fops to access information about the underlying struct file
> for the miscdevice. For example, the Binder driver needs to inspect the
> O_NONBLOCK flag inside the fops->ioctl() hook.
>
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> ---
> rust/kernel/miscdevice.rs | 31 +++++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
Reviewed-by: Lee Jones <lee@xxxxxxxxxx>
> diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
> index 7e2a79b3ae26..0cb79676c139 100644
> --- a/rust/kernel/miscdevice.rs
> +++ b/rust/kernel/miscdevice.rs
> @@ -11,6 +11,7 @@
> use crate::{
> bindings,
> error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
> + fs::File,
> prelude::*,
> str::CStr,
> types::{ForeignOwnable, Opaque},
> @@ -103,10 +104,10 @@ pub trait MiscDevice {
> /// Called when the misc device is opened.
> ///
> /// The returned pointer will be stored as the private data for the file.
> - fn open() -> Result<Self::Ptr>;
> + fn open(_file: &File) -> Result<Self::Ptr>;
>
> /// Called when the misc device is released.
> - fn release(device: Self::Ptr) {
> + fn release(device: Self::Ptr, _file: &File) {
> drop(device);
> }
>
> @@ -117,6 +118,7 @@ fn release(device: Self::Ptr) {
> /// [`kernel::ioctl`]: mod@crate::ioctl
> fn ioctl(
> _device: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,
> + _file: &File,
> _cmd: u32,
> _arg: usize,
> ) -> Result<isize> {
> @@ -133,6 +135,7 @@ fn ioctl(
> #[cfg(CONFIG_COMPAT)]
> fn compat_ioctl(
> _device: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,
> + _file: &File,
> _cmd: u32,
> _arg: usize,
> ) -> Result<isize> {
> @@ -187,7 +190,10 @@ impl<T: MiscDevice> VtableHelper<T> {
> return ret;
> }
>
> - let ptr = match T::open() {
> + // SAFETY:
> + // * The file is valid for the duration of this call.
> + // * There is no active fdget_pos region on the file on this thread.
> + let ptr = match T::open(unsafe { File::from_raw_file(file) }) {
> Ok(ptr) => ptr,
> Err(err) => return err.to_errno(),
> };
> @@ -211,7 +217,10 @@ impl<T: MiscDevice> VtableHelper<T> {
> // SAFETY: The release call of a file owns the private data.
> let ptr = unsafe { <T::Ptr as ForeignOwnable>::from_foreign(private) };
>
> - T::release(ptr);
> + // SAFETY:
> + // * The file is valid for the duration of this call.
> + // * There is no active fdget_pos region on the file on this thread.
> + T::release(ptr, unsafe { File::from_raw_file(file) });
>
> 0
> }
> @@ -229,7 +238,12 @@ impl<T: MiscDevice> VtableHelper<T> {
> // SAFETY: Ioctl calls can borrow the private data of the file.
> let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
>
> - match T::ioctl(device, cmd, arg as usize) {
> + // SAFETY:
> + // * The file is valid for the duration of this call.
> + // * There is no active fdget_pos region on the file on this thread.
> + let file = unsafe { File::from_raw_file(file) };
> +
> + match T::ioctl(device, file, cmd, arg as usize) {
> Ok(ret) => ret as c_long,
> Err(err) => err.to_errno() as c_long,
> }
> @@ -249,7 +263,12 @@ impl<T: MiscDevice> VtableHelper<T> {
> // SAFETY: Ioctl calls can borrow the private data of the file.
> let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
>
> - match T::compat_ioctl(device, cmd, arg as usize) {
> + // SAFETY:
> + // * The file is valid for the duration of this call.
> + // * There is no active fdget_pos region on the file on this thread.
> + let file = unsafe { File::from_raw_file(file) };
> +
> + match T::compat_ioctl(device, file, cmd, arg as usize) {
> Ok(ret) => ret as c_long,
> Err(err) => err.to_errno() as c_long,
> }
>
> --
> 2.47.1.613.gc27f4b7a9f-goog
>
--
Lee Jones [李琼斯]
