Merge tag 'lsm-pr-20260814' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull LSM updates from Paul Moore:

 - Remove task_euid()

   The task_euid(), and Rust counterpart, was never widely used, for
   good reason, and now that the only user is gone we're removing it to
   rid ourselves of both dead and funky code.

 - Documentation improvements

   Correct some of the kdoc comments for security_task_prctl() and
   clarify the rust comments on task UID accessors.

 - Fix a memory leak in the LSM syscall selftests

* tag 'lsm-pr-20260814' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  selftests/lsm: Fix memory leak in attr_lsm_count
  cred: delete task_euid()
  rust: task: clarify comments on task UID accessors
  lsm: clarify security_task_prctl() hook documentation

7 files changed, 10 insertions, 26 deletions

diff --git a/Documentation/security/credentials.rst b/Documentation/security/credentials.rst
index 4996838491b1..a39a2a2f67aa 100644
--- a/Documentation/security/credentials.rst
+++ b/Documentation/security/credentials.rst
@@ -393,16 +393,14 @@ the credentials so obtained when they're finished with.
    The result of ``__task_cred()`` should not be passed directly to
    ``get_cred()`` as this may race with ``commit_cred()``.
 
-There are a couple of convenience functions to access bits of another task's
-credentials, hiding the RCU magic from the caller::
+There is a convenience function to access bits of another task's credentials,
+hiding the RCU magic from the caller::
 
 	uid_t task_uid(task)		Task's real UID
-	uid_t task_euid(task)		Task's effective UID
 
 If the caller is holding the RCU read lock at the time anyway, then::
 
 	__task_cred(task)->uid
-	__task_cred(task)->euid
 
 should be used instead.  Similarly, if multiple aspects of a task's credentials
 need to be accessed, RCU read lock should be used, ``__task_cred()`` called,
diff --git a/Documentation/translations/zh_CN/security/credentials.rst b/Documentation/translations/zh_CN/security/credentials.rst
index 88fcd9152ffe..20c8696f8198 100644
--- a/Documentation/translations/zh_CN/security/credentials.rst
+++ b/Documentation/translations/zh_CN/security/credentials.rst
@@ -337,15 +337,13 @@ const指针上操作，因此不需要进行类型转换，但需要临时放弃
    ``__task_cred()`` 的结果不应直接传递给 ``get_cred()`` ，
    因为这可能与 ``commit_cred()`` 发生竞争条件。
 
-还有一些方便的函数可以访问另一个任务凭据的特定部分，将RCU操作对调用方隐藏起来::
+有一个方便的函数可用于访问另一个任务凭据的特定部分，从而对调用方隐藏RCU机制::
 
 	uid_t task_uid(task)		Task's real UID
-	uid_t task_euid(task)		Task's effective UID
 
 如果调用方在此时已经持有RCU读锁，则应使用::
 
 	__task_cred(task)->uid
-	__task_cred(task)->euid
 
 类似地，如果需要访问任务凭据的多个方面，应使用RCU读锁，调用 ``__task_cred()``
 函数，将结果存储在临时指针中，然后从临时指针中调用凭据的各个方面，最后释放锁。
diff --git a/include/linux/cred.h b/include/linux/cred.h
index c6676265a985..6ef1750c93e2 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -371,7 +371,6 @@ DEFINE_FREE(put_cred, struct cred *, if (!IS_ERR_OR_NULL(_T)) put_cred(_T))
 })
 
 #define task_uid(task)		(task_cred_xxx((task), uid))
-#define task_euid(task)		(task_cred_xxx((task), euid))
 #define task_ucounts(task)	(task_cred_xxx((task), ucounts))
 
 #define current_cred_xxx(xxx)			\
diff --git a/rust/helpers/task.c b/rust/helpers/task.c
index c0e1a06ede78..b46b1433a67e 100644
--- a/rust/helpers/task.c
+++ b/rust/helpers/task.c
@@ -28,11 +28,6 @@ __rust_helper kuid_t rust_helper_task_uid(struct task_struct *task)
 	return task_uid(task);
 }
 
-__rust_helper kuid_t rust_helper_task_euid(struct task_struct *task)
-{
-	return task_euid(task);
-}
-
 #ifndef CONFIG_USER_NS
 __rust_helper uid_t rust_helper_from_kuid(struct user_namespace *to, kuid_t uid)
 {
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 38273f4eedb5..c2b3457b700c 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -210,20 +210,13 @@ impl Task {
         unsafe { *ptr::addr_of!((*self.as_ptr()).pid) }
     }
 
-    /// Returns the UID of the given task.
+    /// Returns the objective real UID of the given task.
     #[inline]
     pub fn uid(&self) -> Kuid {
         // SAFETY: It's always safe to call `task_uid` on a valid task.
         Kuid::from_raw(unsafe { bindings::task_uid(self.as_ptr()) })
     }
 
-    /// Returns the effective UID of the given task.
-    #[inline]
-    pub fn euid(&self) -> Kuid {
-        // SAFETY: It's always safe to call `task_euid` on a valid task.
-        Kuid::from_raw(unsafe { bindings::task_euid(self.as_ptr()) })
-    }
-
     /// Determines whether the given task has pending signals.
     #[inline]
     pub fn signal_pending(&self) -> bool {
@@ -371,7 +364,7 @@ impl PartialEq for Task {
 impl Eq for Task {}
 
 impl Kuid {
-    /// Get the current euid.
+    /// Get the current subjective effective UID.
     #[inline]
     pub fn current_euid() -> Kuid {
         // SAFETY: Just an FFI call.
diff --git a/security/security.c b/security/security.c
index 71aea8fdf014..2ee276ab15c5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -3301,15 +3301,14 @@ int security_task_kill(struct task_struct *p, struct kernel_siginfo *info,
 }
 
 /**
- * security_task_prctl() - Check if a prctl op is allowed
+ * security_task_prctl() - Handle an LSM specific prctl() call
  * @option: operation
  * @arg2: argument
  * @arg3: argument
  * @arg4: argument
  * @arg5: argument
  *
- * Check permission before performing a process control operation on the
- * current process.
+ * Handle lsm specific prctl() operations.
  *
  * Return: Return -ENOSYS if no-one wanted to handle this op, any other value
  *         to cause prctl() to return immediately with that value.
diff --git a/tools/testing/selftests/lsm/common.c b/tools/testing/selftests/lsm/common.c
index 9ad258912646..927dce4f04cb 100644
--- a/tools/testing/selftests/lsm/common.c
+++ b/tools/testing/selftests/lsm/common.c
@@ -76,7 +76,7 @@ int attr_lsm_count(void)
 		return 0;
 
 	if (read_sysfs_lsms(names, sysconf(_SC_PAGESIZE)))
-		return 0;
+		goto out;
 
 	if (strstr(names, "selinux"))
 		count++;
@@ -85,5 +85,7 @@ int attr_lsm_count(void)
 	if (strstr(names, "apparmor"))
 		count++;
 
+out:
+	free(names);
 	return count;
 }