mirror of
https://github.com/followmsi/android_kernel_google_msm.git
synced 2024-11-06 23:17:41 +00:00
7a238fcba0
Fix exit race by splitting the nsproxy putting into two pieces. First piece reduces the nsproxy refcount. If we dropped the last reference, then it puts the mnt_ns, and returns the nsproxy as a hint to the caller. Else it returns NULL. The second piece of exiting task namespaces sets tsk->nsproxy to NULL, and drops the references to other namespaces and frees the nsproxy only if an nsproxy was passed in. A little awkward and should probably be reworked, but hopefully it fixes the NFS oops. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Daniel Hokka Zakrisson <daniel@hozac.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
163 lines
3.1 KiB
C
163 lines
3.1 KiB
C
/*
|
|
* Copyright (C) 2006 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.
|
|
*
|
|
* Jun 2006 - namespaces support
|
|
* OpenVZ, SWsoft Inc.
|
|
* Pavel Emelianov <xemul@openvz.org>
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/version.h>
|
|
#include <linux/nsproxy.h>
|
|
#include <linux/init_task.h>
|
|
#include <linux/mnt_namespace.h>
|
|
#include <linux/utsname.h>
|
|
#include <linux/pid_namespace.h>
|
|
|
|
struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
|
|
|
|
static inline void get_nsproxy(struct nsproxy *ns)
|
|
{
|
|
atomic_inc(&ns->count);
|
|
}
|
|
|
|
void get_task_namespaces(struct task_struct *tsk)
|
|
{
|
|
struct nsproxy *ns = tsk->nsproxy;
|
|
if (ns) {
|
|
get_nsproxy(ns);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* creates a copy of "orig" with refcount 1.
|
|
* This does not grab references to the contained namespaces,
|
|
* so that needs to be done by dup_namespaces.
|
|
*/
|
|
static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
|
|
{
|
|
struct nsproxy *ns;
|
|
|
|
ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
|
|
if (ns)
|
|
atomic_set(&ns->count, 1);
|
|
return ns;
|
|
}
|
|
|
|
/*
|
|
* copies the nsproxy, setting refcount to 1, and grabbing a
|
|
* reference to all contained namespaces. Called from
|
|
* sys_unshare()
|
|
*/
|
|
struct nsproxy *dup_namespaces(struct nsproxy *orig)
|
|
{
|
|
struct nsproxy *ns = clone_namespaces(orig);
|
|
|
|
if (ns) {
|
|
if (ns->mnt_ns)
|
|
get_mnt_ns(ns->mnt_ns);
|
|
if (ns->uts_ns)
|
|
get_uts_ns(ns->uts_ns);
|
|
if (ns->ipc_ns)
|
|
get_ipc_ns(ns->ipc_ns);
|
|
if (ns->pid_ns)
|
|
get_pid_ns(ns->pid_ns);
|
|
}
|
|
|
|
return ns;
|
|
}
|
|
|
|
/*
|
|
* called from clone. This now handles copy for nsproxy and all
|
|
* namespaces therein.
|
|
*/
|
|
int copy_namespaces(int flags, struct task_struct *tsk)
|
|
{
|
|
struct nsproxy *old_ns = tsk->nsproxy;
|
|
struct nsproxy *new_ns;
|
|
int err = 0;
|
|
|
|
if (!old_ns)
|
|
return 0;
|
|
|
|
get_nsproxy(old_ns);
|
|
|
|
if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
|
|
return 0;
|
|
|
|
new_ns = clone_namespaces(old_ns);
|
|
if (!new_ns) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
tsk->nsproxy = new_ns;
|
|
|
|
err = copy_mnt_ns(flags, tsk);
|
|
if (err)
|
|
goto out_ns;
|
|
|
|
err = copy_utsname(flags, tsk);
|
|
if (err)
|
|
goto out_uts;
|
|
|
|
err = copy_ipcs(flags, tsk);
|
|
if (err)
|
|
goto out_ipc;
|
|
|
|
err = copy_pid_ns(flags, tsk);
|
|
if (err)
|
|
goto out_pid;
|
|
|
|
out:
|
|
put_and_finalize_nsproxy(old_ns);
|
|
return err;
|
|
|
|
out_pid:
|
|
if (new_ns->ipc_ns)
|
|
put_ipc_ns(new_ns->ipc_ns);
|
|
out_ipc:
|
|
if (new_ns->uts_ns)
|
|
put_uts_ns(new_ns->uts_ns);
|
|
out_uts:
|
|
if (new_ns->mnt_ns)
|
|
put_mnt_ns(new_ns->mnt_ns);
|
|
out_ns:
|
|
tsk->nsproxy = old_ns;
|
|
kfree(new_ns);
|
|
goto out;
|
|
}
|
|
|
|
struct nsproxy *put_nsproxy(struct nsproxy *ns)
|
|
{
|
|
if (ns) {
|
|
if (atomic_dec_and_test(&ns->count)) {
|
|
if (ns->mnt_ns) {
|
|
put_mnt_ns(ns->mnt_ns);
|
|
ns->mnt_ns = NULL;
|
|
}
|
|
return ns;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
void free_nsproxy(struct nsproxy *ns)
|
|
{
|
|
if (ns->mnt_ns)
|
|
put_mnt_ns(ns->mnt_ns);
|
|
if (ns->uts_ns)
|
|
put_uts_ns(ns->uts_ns);
|
|
if (ns->ipc_ns)
|
|
put_ipc_ns(ns->ipc_ns);
|
|
if (ns->pid_ns)
|
|
put_pid_ns(ns->pid_ns);
|
|
kfree(ns);
|
|
}
|