--- kernel/cred.c
+++ kernel/cred.c
@@ -16,7 +16,6 @@
#include <linux/init_task.h>
#include <linux/security.h>
#include <linux/cn_proc.h>
-#include "cred-internals.h"
#if 0
#define kdebug(FMT, ...) \
@@ -209,6 +208,31 @@ 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.
@@ -231,13 +255,13 @@ struct cred *cred_alloc_blank(void)
#endif
atomic_set(&new->usage, 1);
+#ifdef CONFIG_DEBUG_CREDENTIALS
+ new->magic = CRED_MAGIC;
+#endif
if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
goto error;
-#ifdef CONFIG_DEBUG_CREDENTIALS
- new->magic = CRED_MAGIC;
-#endif
return new;
error:
@@ -553,8 +577,6 @@ int commit_creds(struct cred *new)
atomic_dec(&old->user->processes);
alter_cred_subscribers(old, -2);
- sched_switch_user(task);
-
/* send notifications */
if (new->uid != old->uid ||
new->euid != old->euid ||
@@ -696,6 +718,8 @@ struct cred *prepare_kernel_cred(struct
validate_creds(old);
*new = *old;
+ atomic_set(&new->usage, 1);
+ set_cred_subscribers(new, 0);
get_uid(new->user);
get_group_info(new->group_info);
@@ -713,8 +737,6 @@ struct cred *prepare_kernel_cred(struct
if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
goto error;
- atomic_set(&new->usage, 1);
- set_cred_subscribers(new, 0);
put_cred(old);
validate_creds(new);
return new;
@@ -787,7 +809,11 @@ bool creds_are_invalid(const struct cred
if (cred->magic != CRED_MAGIC)
return true;
#ifdef CONFIG_SECURITY_SELINUX
- if (selinux_is_enabled()) {
+ /*
+ * cred->security == NULL if security_cred_alloc_blank() or
+ * security_prepare_creds() returned an error.
+ */
+ if (selinux_is_enabled() && cred->security) {
if ((unsigned long) cred->security < PAGE_SIZE)
return true;
if ((*(u32 *)cred->security & 0xffffff00) ==
projects / ziggy471-frankenstein-kernel.git / blobdiff