security: create task_free security callback

The current LSM interface to cred_free is not sufficient for allowing
an LSM to track the life and death of a task. This patch adds the
task_free hook so that an LSM can clean up resources on task death.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/security/capability.c b/security/capability.c
index 2f680eb02b59..5bb21b1c448c 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -358,6 +358,10 @@ static int cap_task_create(unsigned long clone_flags)
         return 0;
 }
 
+static void cap_task_free(struct task_struct *task)
+{
+}
+
 static int cap_cred_alloc_blank(struct cred *cred, gfp_t gfp)
 {
         return 0;
@@ -954,6 +958,7 @@ void __init security_fixup_ops(struct security_operations *ops)
         set_to_cap_if_null(ops, file_receive);
         set_to_cap_if_null(ops, dentry_open);
         set_to_cap_if_null(ops, task_create);
+        set_to_cap_if_null(ops, task_free);
         set_to_cap_if_null(ops, cred_alloc_blank);
         set_to_cap_if_null(ops, cred_free);
         set_to_cap_if_null(ops, cred_prepare);