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, 5 insertions, 3 deletions

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index d87247d2641f..7f54ba942429 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -145,8 +145,8 @@ extern struct cred init_cred;
         .group_leader   = &tsk,                                         \
         .real_cred      = &init_cred,                                   \
         .cred           = &init_cred,                                   \
-        .cred_exec_mutex =                                              \
-                 __MUTEX_INITIALIZER(tsk.cred_exec_mutex),              \
+        .cred_guard_mutex =                                             \
+                 __MUTEX_INITIALIZER(tsk.cred_guard_mutex),             \
         .comm           = "swapper",                                    \
         .thread         = INIT_THREAD,                                  \
         .fs             = &init_fs,                                     \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3fa82b353c98..5932ace22400 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1247,7 +1247,9 @@ struct task_struct {
                                          * credentials (COW) */
         const struct cred *cred;        /* effective (overridable) subjective task
                                          * credentials (COW) */
-        struct mutex cred_exec_mutex;   /* execve vs ptrace cred calculation mutex */
+        struct mutex cred_guard_mutex;  /* guard against foreign influences on
+                                         * credential calculations
+                                         * (notably. ptrace) */
 
         char comm[TASK_COMM_LEN]; /* executable name excluding path
                                      - access with [gs]et_task_comm (which lock