mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-21 11:44:01 +08:00
c4a4d60379
Optimize performance and prepare for the removal of the user_ns reference from user_struct. Remove the slow long walk through cred->user->user_ns and instead go straight to cred->user_ns. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
121 lines
2.5 KiB
C
121 lines
2.5 KiB
C
/*
|
|
* Copyright (C) 2004 IBM Corporation
|
|
*
|
|
* Author: Serge Hallyn <serue@us.ibm.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation, version 2 of the
|
|
* License.
|
|
*/
|
|
|
|
#include <linux/export.h>
|
|
#include <linux/uts.h>
|
|
#include <linux/utsname.h>
|
|
#include <linux/err.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/user_namespace.h>
|
|
#include <linux/proc_fs.h>
|
|
|
|
static struct uts_namespace *create_uts_ns(void)
|
|
{
|
|
struct uts_namespace *uts_ns;
|
|
|
|
uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
|
|
if (uts_ns)
|
|
kref_init(&uts_ns->kref);
|
|
return uts_ns;
|
|
}
|
|
|
|
/*
|
|
* Clone a new ns copying an original utsname, setting refcount to 1
|
|
* @old_ns: namespace to clone
|
|
* Return NULL on error (failure to kmalloc), new ns otherwise
|
|
*/
|
|
static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
|
|
struct uts_namespace *old_ns)
|
|
{
|
|
struct uts_namespace *ns;
|
|
|
|
ns = create_uts_ns();
|
|
if (!ns)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
down_read(&uts_sem);
|
|
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
|
|
ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
|
|
up_read(&uts_sem);
|
|
return ns;
|
|
}
|
|
|
|
/*
|
|
* Copy task tsk's utsname namespace, or clone it if flags
|
|
* specifies CLONE_NEWUTS. In latter case, changes to the
|
|
* utsname of this process won't be seen by parent, and vice
|
|
* versa.
|
|
*/
|
|
struct uts_namespace *copy_utsname(unsigned long flags,
|
|
struct task_struct *tsk)
|
|
{
|
|
struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
|
|
struct uts_namespace *new_ns;
|
|
|
|
BUG_ON(!old_ns);
|
|
get_uts_ns(old_ns);
|
|
|
|
if (!(flags & CLONE_NEWUTS))
|
|
return old_ns;
|
|
|
|
new_ns = clone_uts_ns(tsk, old_ns);
|
|
|
|
put_uts_ns(old_ns);
|
|
return new_ns;
|
|
}
|
|
|
|
void free_uts_ns(struct kref *kref)
|
|
{
|
|
struct uts_namespace *ns;
|
|
|
|
ns = container_of(kref, struct uts_namespace, kref);
|
|
put_user_ns(ns->user_ns);
|
|
kfree(ns);
|
|
}
|
|
|
|
static void *utsns_get(struct task_struct *task)
|
|
{
|
|
struct uts_namespace *ns = NULL;
|
|
struct nsproxy *nsproxy;
|
|
|
|
rcu_read_lock();
|
|
nsproxy = task_nsproxy(task);
|
|
if (nsproxy) {
|
|
ns = nsproxy->uts_ns;
|
|
get_uts_ns(ns);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return ns;
|
|
}
|
|
|
|
static void utsns_put(void *ns)
|
|
{
|
|
put_uts_ns(ns);
|
|
}
|
|
|
|
static int utsns_install(struct nsproxy *nsproxy, void *ns)
|
|
{
|
|
get_uts_ns(ns);
|
|
put_uts_ns(nsproxy->uts_ns);
|
|
nsproxy->uts_ns = ns;
|
|
return 0;
|
|
}
|
|
|
|
const struct proc_ns_operations utsns_operations = {
|
|
.name = "uts",
|
|
.type = CLONE_NEWUTS,
|
|
.get = utsns_get,
|
|
.put = utsns_put,
|
|
.install = utsns_install,
|
|
};
|
|
|