CRED: Detach the credentials from task_struct
Detach the credentials from task_struct, duplicating them in copy_process()
and releasing them in __put_task_struct().
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/kernel/cred.c b/kernel/cred.c
new file mode 100644
index 0000000..833244a
--- /dev/null
+++ b/kernel/cred.c
@@ -0,0 +1,96 @@
+/* Task credentials management
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <linux/module.h>
+#include <linux/cred.h>
+#include <linux/sched.h>
+#include <linux/key.h>
+#include <linux/keyctl.h>
+#include <linux/init_task.h>
+#include <linux/security.h>
+
+/*
+ * The initial credentials for the initial task
+ */
+struct cred init_cred = {
+ .usage = ATOMIC_INIT(3),
+ .securebits = SECUREBITS_DEFAULT,
+ .cap_inheritable = CAP_INIT_INH_SET,
+ .cap_permitted = CAP_FULL_SET,
+ .cap_effective = CAP_INIT_EFF_SET,
+ .cap_bset = CAP_INIT_BSET,
+ .user = INIT_USER,
+ .group_info = &init_groups,
+};
+
+/*
+ * The RCU callback to actually dispose of a set of credentials
+ */
+static void put_cred_rcu(struct rcu_head *rcu)
+{
+ struct cred *cred = container_of(rcu, struct cred, rcu);
+
+ BUG_ON(atomic_read(&cred->usage) != 0);
+
+ key_put(cred->thread_keyring);
+ key_put(cred->request_key_auth);
+ put_group_info(cred->group_info);
+ free_uid(cred->user);
+ security_cred_free(cred);
+ kfree(cred);
+}
+
+/**
+ * __put_cred - Destroy a set of credentials
+ * @sec: The record to release
+ *
+ * Destroy a set of credentials on which no references remain.
+ */
+void __put_cred(struct cred *cred)
+{
+ call_rcu(&cred->rcu, put_cred_rcu);
+}
+EXPORT_SYMBOL(__put_cred);
+
+/*
+ * Copy credentials for the new process created by fork()
+ */
+int copy_creds(struct task_struct *p, unsigned long clone_flags)
+{
+ struct cred *pcred;
+ int ret;
+
+ pcred = kmemdup(p->cred, sizeof(*p->cred), GFP_KERNEL);
+ if (!pcred)
+ return -ENOMEM;
+
+#ifdef CONFIG_SECURITY
+ pcred->security = NULL;
+#endif
+
+ ret = security_cred_alloc(pcred);
+ if (ret < 0) {
+ kfree(pcred);
+ return ret;
+ }
+
+ atomic_set(&pcred->usage, 1);
+ get_group_info(pcred->group_info);
+ get_uid(pcred->user);
+ key_get(pcred->thread_keyring);
+ key_get(pcred->request_key_auth);
+
+ atomic_inc(&pcred->user->processes);
+
+ /* RCU assignment is unneeded here as no-one can have accessed this
+ * pointer yet, barring us */
+ p->cred = pcred;
+ return 0;
+}