27c7518e7f
In the last kernel cycle we migrated most of the `core::ffi` cases in
commit d072acda48 ("rust: use custom FFI integer types"):
Currently FFI integer types are defined in libcore. This commit
creates the `ffi` crate and asks bindgen to use that crate for FFI
integer types instead of `core::ffi`.
This commit is preparatory and no type changes are made in this
commit yet.
Finish now the few remaining/new cases so that we perform the actual
remapping in the next commit as planned.
Acked-by: Jocelyn Falempe <jfalempe@redhat.com> # drm
Link: https://lore.kernel.org/rust-for-linux/CANiq72m_rg42SvZK=bF2f0yEoBLVA33UBhiAsv8THhVu=G2dPA@mail.gmail.com/
Link: https://lore.kernel.org/all/cc9253fa-9d5f-460b-9841-94948fb6580c@redhat.com/
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
70 lines
2.3 KiB
Rust
70 lines
2.3 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
// Copyright (C) 2024 Google LLC.
|
|
|
|
//! Linux Security Modules (LSM).
|
|
//!
|
|
//! C header: [`include/linux/security.h`](srctree/include/linux/security.h).
|
|
|
|
use crate::{
|
|
bindings,
|
|
error::{to_result, Result},
|
|
};
|
|
|
|
/// A security context string.
|
|
///
|
|
/// # Invariants
|
|
///
|
|
/// The `ctx` field corresponds to a valid security context as returned by a successful call to
|
|
/// `security_secid_to_secctx`, that has not yet been destroyed by `security_release_secctx`.
|
|
pub struct SecurityCtx {
|
|
ctx: bindings::lsm_context,
|
|
}
|
|
|
|
impl SecurityCtx {
|
|
/// Get the security context given its id.
|
|
pub fn from_secid(secid: u32) -> Result<Self> {
|
|
// SAFETY: `struct lsm_context` can be initialized to all zeros.
|
|
let mut ctx: bindings::lsm_context = unsafe { core::mem::zeroed() };
|
|
|
|
// SAFETY: Just a C FFI call. The pointer is valid for writes.
|
|
to_result(unsafe { bindings::security_secid_to_secctx(secid, &mut ctx) })?;
|
|
|
|
// INVARIANT: If the above call did not fail, then we have a valid security context.
|
|
Ok(Self { ctx })
|
|
}
|
|
|
|
/// Returns whether the security context is empty.
|
|
pub fn is_empty(&self) -> bool {
|
|
self.ctx.len == 0
|
|
}
|
|
|
|
/// Returns the length of this security context.
|
|
pub fn len(&self) -> usize {
|
|
self.ctx.len as usize
|
|
}
|
|
|
|
/// Returns the bytes for this security context.
|
|
pub fn as_bytes(&self) -> &[u8] {
|
|
let ptr = self.ctx.context;
|
|
if ptr.is_null() {
|
|
debug_assert_eq!(self.len(), 0);
|
|
// We can't pass a null pointer to `slice::from_raw_parts` even if the length is zero.
|
|
return &[];
|
|
}
|
|
|
|
// SAFETY: The call to `security_secid_to_secctx` guarantees that the pointer is valid for
|
|
// `self.len()` bytes. Furthermore, if the length is zero, then we have ensured that the
|
|
// pointer is not null.
|
|
unsafe { core::slice::from_raw_parts(ptr.cast(), self.len()) }
|
|
}
|
|
}
|
|
|
|
impl Drop for SecurityCtx {
|
|
fn drop(&mut self) {
|
|
// SAFETY: By the invariant of `Self`, this frees a context that came from a successful
|
|
// call to `security_secid_to_secctx` and has not yet been destroyed by
|
|
// `security_release_secctx`.
|
|
unsafe { bindings::security_release_secctx(&mut self.ctx) };
|
|
}
|
|
}
|