[PATCH v6 0/8] File abstractions needed by Rust Binder

[Alice Ryhl <aliceryhl@google.com>]

This patchset contains the file abstractions needed by the Rust
implementation of the Binder driver.

Please see the Rust Binder RFC for usage examples:
https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@google.com/

Users of "rust: types: add `NotThreadSafe`":
	[PATCH 5/9] rust: file: add `FileDescriptorReservation`

Users of "rust: task: add `Task::current_raw`":
	[PATCH 7/9] rust: file: add `Kuid` wrapper
	[PATCH 8/9] rust: file: add `DeferredFdCloser`

Users of "rust: file: add Rust abstraction for `struct file`":
	[PATCH RFC 02/20] rust_binder: add binderfs support to Rust binder
	[PATCH RFC 03/20] rust_binder: add threading support

Users of "rust: cred: add Rust abstraction for `struct cred`":
	[PATCH RFC 05/20] rust_binder: add nodes and context managers
	[PATCH RFC 06/20] rust_binder: add oneway transactions
	[PATCH RFC 11/20] rust_binder: send nodes in transaction
	[PATCH RFC 13/20] rust_binder: add BINDER_TYPE_FD support

Users of "rust: security: add abstraction for secctx":
	[PATCH RFC 06/20] rust_binder: add oneway transactions

Users of "rust: file: add `FileDescriptorReservation`":
	[PATCH RFC 13/20] rust_binder: add BINDER_TYPE_FD support
	[PATCH RFC 14/20] rust_binder: add BINDER_TYPE_FDA support

Users of "rust: file: add `Kuid` wrapper":
	[PATCH RFC 05/20] rust_binder: add nodes and context managers
	[PATCH RFC 06/20] rust_binder: add oneway transactions

Users of "rust: file: add abstraction for `poll_table`":
	[PATCH RFC 07/20] rust_binder: add epoll support

This patchset has some uses of read_volatile in place of READ_ONCE.
Please see the following rfc for context on this:
https://lore.kernel.org/all/20231025195339.1431894-1-boqun.feng@gmail.com/

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Changes in v6:
- Introduce file sharing modes.
- Rewrite most documentation for `struct file` wrapper.
- Drop `DeferredFdCloser`. It will be sent later when it can be placed
  somewhere where only Rust Binder can use it.
- Rebase on top of rust-next: 97ab3e8eec0c ("rust: alloc: fix dangling pointer in VecExt<T>::reserve()")
- Link to v5: https://lore.kernel.org/r/20240209-alice-file-v5-0-a37886783025@google.com

Changes in v5:
- Pass a null pointer to task_tgid_nr_ns.
- Fix some typos and other formatting issues.
- Add Reviewed-by where appropriate.
- Link to v4: https://lore.kernel.org/r/20240202-alice-file-v4-0-fc9c2080663b@google.com

Changes in v4:
- Moved the two really simple patches to the beginning of the patchset.
- Update Send safety comments.
- Use srctree relative links.
- Mention that `Credential::euid` is immutable.
- Update some safety comments to mention the invariant on Self.
- Use new name for close_fd_get_file.
- Move safety comments on DeferredFdCloser around and be more explicit
  about how many refcounts we own.
- Reword safety comments related to _qproc.
- Add Reviewed-by where appropriate.
- Link to v3: https://lore.kernel.org/r/20240118-alice-file-v3-0-9694b6f9580c@google.com

Changes in v3:
- Completely rewrite comments about refcounting in the first patch.
  - And add a note to the documentation in fs/file.c.
- Discuss speculation gadgets in commit message for the Kuid wrapper.
- Introduce NotThreadSafe and Task::current_raw patches and use them in
  later patches.
- Improve safety comments in DeferredFdCloser.
- Some other minor changes.
- Link to v2: https://lore.kernel.org/r/20231206-alice-file-v2-0-af617c0d9d94@google.com

Changes in v2:
- Update various docs and safety comments.
- Rename method names to match the C name.
- Use ordinary read instead of READ_ONCE in File::cred.
- Changed null check in secctx.
- Add type alias for PhantomData in FileDescriptorReservation.
- Use Kuid::from_raw in Kuid::current_euid.
- Make DeferredFdCloser fallible if it is unable to schedule a task
  work. And also schedule the task work *before* closing the file.
- Moved PollCondVar to rust/kernel/sync.
- Updated PollCondVar to use wake_up_pollfree.
- Link to v1: https://lore.kernel.org/all/20231129-alice-file-v1-0-f81afe8c7261@google.com/

Link to RFC:
https://lore.kernel.org/all/20230720152820.3566078-1-aliceryhl@google.com/

---
Alice Ryhl (5):
      rust: types: add `NotThreadSafe`
      rust: task: add `Task::current_raw`
      rust: security: add abstraction for secctx
      rust: file: add `Kuid` wrapper
      rust: file: add abstraction for `poll_table`

Wedson Almeida Filho (3):
      rust: file: add Rust abstraction for `struct file`
      rust: cred: add Rust abstraction for `struct cred`
      rust: file: add `FileDescriptorReservation`

 fs/file.c                       |   7 +
 rust/bindings/bindings_helper.h |   6 +
 rust/helpers.c                  |  86 +++++++++
 rust/kernel/cred.rs             |  83 ++++++++
 rust/kernel/file.rs             | 416 ++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |   3 +
 rust/kernel/security.rs         |  72 +++++++
 rust/kernel/sync.rs             |   1 +
 rust/kernel/sync/lock.rs        |  13 +-
 rust/kernel/sync/poll.rs        | 119 ++++++++++++
 rust/kernel/task.rs             |  91 ++++++++-
 rust/kernel/types.rs            |  26 +++
 12 files changed, 911 insertions(+), 12 deletions(-)
---
base-commit: 97ab3e8eec0ce79d9e265e6c9e4c480492180409
change-id: 20231123-alice-file-525b98e8a724

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