CRED: Inaugurate COW credentials

[linux-block.git] / security / keys / permission.c

diff --git a/security/keys/permission.c b/security/keys/permission.c
index 13c36164f284ce2b8e5456558535d4fb1d6fc278..5d9fc7b93f2e988f0b96c8fb2e89caacac4147cb 100644 (file)
--- a/security/keys/permission.c
+++ b/security/keys/permission.c
@@ -14,24 +14,27 @@
 #include "internal.h"
 
 /*****************************************************************************/
-/*
- * check to see whether permission is granted to use a key in the desired way,
- * but permit the security modules to override
+/**
+ * key_task_permission - Check a key can be used
+ * @key_ref: The key to check
+ * @cred: The credentials to use
+ * @perm: The permissions to check for
+ *
+ * Check to see whether permission is granted to use a key in the desired way,
+ * but permit the security modules to override.
+ *
+ * The caller must hold either a ref on cred or must hold the RCU readlock or a
+ * spinlock.
  */
-int key_task_permission(const key_ref_t key_ref,
-                       struct task_struct *context,
+int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
                        key_perm_t perm)
 {
-       const struct cred *cred;
        struct key *key;
        key_perm_t kperm;
        int ret;
 
        key = key_ref_to_ptr(key_ref);
 
-       rcu_read_lock();
-       cred = __task_cred(context);
-
        /* use the second 8-bits of permissions for keys the caller owns */
        if (key->uid == cred->fsuid) {
                kperm = key->perm >> 16;
@@ -57,7 +60,6 @@ int key_task_permission(const key_ref_t key_ref,
        kperm = key->perm;
 
 use_these_perms:
-       rcu_read_lock();
 
        /* use the top 8-bits of permissions for keys the caller possesses
         * - possessor permissions are additive with other permissions
@@ -71,7 +73,7 @@ use_these_perms:
                return -EACCES;
 
        /* let LSM be the final arbiter */
-       return security_key_permission(key_ref, context, perm);
+       return security_key_permission(key_ref, cred, perm);
 
 } /* end key_task_permission() */