@@ -21,6 +21,7 @@
#include <linux/phy.h>
#include <linux/refcount.h>
#include <linux/sched.h>
+#include <linux/security.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
@@ -33,6 +33,7 @@
#include <linux/mutex.h>
#include <linux/refcount.h>
#include <linux/sched/signal.h>
+#include <linux/security.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
@@ -220,6 +221,26 @@ void rust_helper_put_cred(const struct cred *cred)
}
EXPORT_SYMBOL_GPL(rust_helper_put_cred);
+#ifndef CONFIG_SECURITY
+void rust_helper_security_cred_getsecid(const struct cred *c, u32 *secid)
+{
+ security_cred_getsecid(c, secid);
+}
+EXPORT_SYMBOL_GPL(rust_helper_security_cred_getsecid);
+
+int rust_helper_security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+{
+ return security_secid_to_secctx(secid, secdata, seclen);
+}
+EXPORT_SYMBOL_GPL(rust_helper_security_secid_to_secctx);
+
+void rust_helper_security_release_secctx(char *secdata, u32 seclen)
+{
+ security_release_secctx(secdata, seclen);
+}
+EXPORT_SYMBOL_GPL(rust_helper_security_release_secctx);
+#endif
+
/*
* `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
* use it in contexts where Rust expects a `usize` like slice (array) indices.
@@ -52,6 +52,14 @@ pub unsafe fn from_ptr<'a>(ptr: *const bindings::cred) -> &'a Credential {
unsafe { &*ptr.cast() }
}
+ /// Get the id for this security context.
+ pub fn get_secid(&self) -> u32 {
+ let mut secid = 0;
+ // SAFETY: The invariants of this type ensures that the pointer is valid.
+ unsafe { bindings::security_cred_getsecid(self.0.get(), &mut secid) };
+ secid
+ }
+
/// Returns the effective UID of the given credential.
pub fn euid(&self) -> bindings::kuid_t {
// SAFETY: By the type invariant, we know that `self.0` is valid. Furthermore, the `euid`
@@ -45,6 +45,7 @@
pub mod page;
pub mod prelude;
pub mod print;
+pub mod security;
mod static_assert;
#[doc(hidden)]
pub mod std_vendor;
new file mode 100644
@@ -0,0 +1,74 @@
+// 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 `secdata` and `seclen` fields correspond to a valid security context as returned by a
+/// successful call to `security_secid_to_secctx`, that has not yet been destroyed by calling
+/// `security_release_secctx`.
+pub struct SecurityCtx {
+ secdata: *mut core::ffi::c_char,
+ seclen: usize,
+}
+
+impl SecurityCtx {
+ /// Get the security context given its id.
+ pub fn from_secid(secid: u32) -> Result<Self> {
+ let mut secdata = core::ptr::null_mut();
+ let mut seclen = 0u32;
+ // SAFETY: Just a C FFI call. The pointers are valid for writes.
+ to_result(unsafe { bindings::security_secid_to_secctx(secid, &mut secdata, &mut seclen) })?;
+
+ // INVARIANT: If the above call did not fail, then we have a valid security context.
+ Ok(Self {
+ secdata,
+ seclen: seclen as usize,
+ })
+ }
+
+ /// Returns whether the security context is empty.
+ pub fn is_empty(&self) -> bool {
+ self.seclen == 0
+ }
+
+ /// Returns the length of this security context.
+ pub fn len(&self) -> usize {
+ self.seclen
+ }
+
+ /// Returns the bytes for this security context.
+ pub fn as_bytes(&self) -> &[u8] {
+ let ptr = self.secdata;
+ if ptr.is_null() {
+ debug_assert_eq!(self.seclen, 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
+ // `seclen` 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.seclen) }
+ }
+}
+
+impl Drop for SecurityCtx {
+ fn drop(&mut self) {
+ // SAFETY: By the invariant of `Self`, this frees a pointer 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(self.secdata, self.seclen as u32) };
+ }
+}