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-rw-r--r--kernel/cred.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/kernel/cred.c b/kernel/cred.c
index a2d5504fbcc2..60bc8b1e32e6 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -209,6 +209,31 @@ void exit_creds(struct task_struct *tsk)
}
}
+/**
+ * get_task_cred - Get another task's objective credentials
+ * @task: The task to query
+ *
+ * Get the objective credentials of a task, pinning them so that they can't go
+ * away. Accessing a task's credentials directly is not permitted.
+ *
+ * The caller must also make sure task doesn't get deleted, either by holding a
+ * ref on task or by holding tasklist_lock to prevent it from being unlinked.
+ */
+const struct cred *get_task_cred(struct task_struct *task)
+{
+ const struct cred *cred;
+
+ rcu_read_lock();
+
+ do {
+ cred = __task_cred((task));
+ BUG_ON(!cred);
+ } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
+
+ rcu_read_unlock();
+ return cred;
+}
+
/*
* Allocate blank credentials, such that the credentials can be filled in at a
* later date without risk of ENOMEM.