CRED: Rename cred_exec_mutex to reflect that it's a guard against ptrace

Rename cred_exec_mutex to reflect that it's a guard against foreign
intervention on a process's credential state, such as is made by ptrace().  The
attachment of a debugger to a process affects execve()'s calculation of the new
credential state - _and_ also setprocattr()'s calculation of that state.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

2 files changed, 7 insertions, 6 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
index 3a039189d707..1bb4d7e5d616 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -167,7 +167,7 @@ EXPORT_SYMBOL(prepare_creds);
 
 /*
  * Prepare credentials for current to perform an execve()
- * - The caller must hold current->cred_exec_mutex
+ * - The caller must hold current->cred_guard_mutex
  */
 struct cred *prepare_exec_creds(void)
 {
@@ -276,7 +276,7 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
         struct cred *new;
         int ret;
 
-        mutex_init(&p->cred_exec_mutex);
+        mutex_init(&p->cred_guard_mutex);
 
         if (
 #ifdef CONFIG_KEYS
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 0692ab5a0d67..27ac80298bfa 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -185,10 +185,11 @@ int ptrace_attach(struct task_struct *task)
         if (same_thread_group(task, current))
                 goto out;
 
-        /* Protect exec's credential calculations against our interference;
-         * SUID, SGID and LSM creds get determined differently under ptrace.
+        /* Protect the target's credential calculations against our
+         * interference; SUID, SGID and LSM creds get determined differently
+         * under ptrace.
          */
-        retval = mutex_lock_interruptible(&task->cred_exec_mutex);
+        retval = mutex_lock_interruptible(&task->cred_guard_mutex);
         if (retval  < 0)
                 goto out;
 
@@ -232,7 +233,7 @@ repeat:
 bad:
         write_unlock_irqrestore(&tasklist_lock, flags);
         task_unlock(task);
-        mutex_unlock(&task->cred_exec_mutex);
+        mutex_unlock(&task->cred_guard_mutex);
 out:
         return retval;
 }