UBUNTU: Ubuntu-4.10.0-4.6

[mirror_ubuntu-zesty-kernel.git] / kernel / cred.c

diff --git a/kernel/cred.c b/kernel/cred.c
index 5f264fb5737dcd01329fdeff02a4143584ba9c38..15b8e8a1cc1c25507291a1031954bc3fbd65fc5b 100644 (file)
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -574,38 +574,30 @@ void __init cred_init(void)
 }
 
 /**
- * prepare_kernel_cred - Prepare a set of credentials for a kernel service
- * @daemon: A userspace daemon to be used as a reference
- *
- * Prepare a set of credentials for a kernel service.  This can then be used to
- * override a task's own credentials so that work can be done on behalf of that
- * task that requires a different subjective context.
- *
- * @daemon is used to provide a base for the security record, but can be NULL.
- * If @daemon is supplied, then the security data will be derived from that;
- * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
+ * clone_cred - Create a new copy of a set of credentials
+ * @old: Credentials to be copied
  *
- * The caller may change these controls afterwards if desired.
+ * Prepare a new set of credentials that is an exact copy of @old. This can
+ * optionally be modified and used to override a task's own credentials so
+ * that work can be done on behalf of that task that requires a different
+ * subjective context.
  *
- * Returns the new credentials or NULL if out of memory.
+ * Returns the new credentials or NULL if @old is NULL or if out of memory.
  *
  * Does not take, and does not return holding current->cred_replace_mutex.
  */
-struct cred *prepare_kernel_cred(struct task_struct *daemon)
+struct cred *clone_cred(const struct cred *old)
 {
-       const struct cred *old;
        struct cred *new;
 
+       if (!old)
+               return NULL;
+
        new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
        if (!new)
                return NULL;
 
-       kdebug("prepare_kernel_cred() alloc %p", new);
-
-       if (daemon)
-               old = get_task_cred(daemon);
-       else
-               old = get_cred(&init_cred);
+       kdebug("clone_cred() alloc %p", new);
 
        validate_creds(old);
 
@@ -630,15 +622,47 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
        if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
                goto error;
 
-       put_cred(old);
        validate_creds(new);
        return new;
 
 error:
        put_cred(new);
-       put_cred(old);
        return NULL;
 }
+EXPORT_SYMBOL(clone_cred);
+
+/**
+ * prepare_kernel_cred - Prepare a set of credentials for a kernel service
+ * @daemon: A userspace daemon to be used as a reference
+ *
+ * Prepare a set of credentials for a kernel service.  This can then be used to
+ * override a task's own credentials so that work can be done on behalf of that
+ * task that requires a different subjective context.
+ *
+ * @daemon is used to provide a base for the security record, but can be NULL.
+ * If @daemon is supplied, then the security data will be derived from that;
+ * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
+ *
+ * The caller may change these controls afterwards if desired.
+ *
+ * Returns the new credentials or NULL if out of memory.
+ *
+ * Does not take, and does not return holding current->cred_replace_mutex.
+ */
+struct cred *prepare_kernel_cred(struct task_struct *daemon)
+{
+       const struct cred *old;
+       struct cred *new;
+
+       if (daemon)
+               old = get_task_cred(daemon);
+       else
+               old = get_cred(&init_cred);
+
+       new = clone_cred(old);
+       put_cred(old);
+       return new;
+}
 EXPORT_SYMBOL(prepare_kernel_cred);
 
 /**