mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-25 02:09:42 +00:00
![Alexey Dobriyan](/assets/img/avatar_default.png)
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
/*
|
|
* linux/ipc/namespace.c
|
|
* Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
|
|
*/
|
|
|
|
#include <linux/ipc.h>
|
|
#include <linux/msg.h>
|
|
#include <linux/ipc_namespace.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/nsproxy.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/mount.h>
|
|
|
|
#include "util.h"
|
|
|
|
static struct ipc_namespace *create_ipc_ns(void)
|
|
{
|
|
struct ipc_namespace *ns;
|
|
int err;
|
|
|
|
ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
|
|
if (ns == NULL)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
atomic_set(&ns->count, 1);
|
|
err = mq_init_ns(ns);
|
|
if (err) {
|
|
kfree(ns);
|
|
return ERR_PTR(err);
|
|
}
|
|
atomic_inc(&nr_ipc_ns);
|
|
|
|
sem_init_ns(ns);
|
|
msg_init_ns(ns);
|
|
shm_init_ns(ns);
|
|
|
|
/*
|
|
* msgmni has already been computed for the new ipc ns.
|
|
* Thus, do the ipcns creation notification before registering that
|
|
* new ipcns in the chain.
|
|
*/
|
|
ipcns_notify(IPCNS_CREATED);
|
|
register_ipcns_notifier(ns);
|
|
|
|
return ns;
|
|
}
|
|
|
|
struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
|
|
{
|
|
if (!(flags & CLONE_NEWIPC))
|
|
return get_ipc_ns(ns);
|
|
return create_ipc_ns();
|
|
}
|
|
|
|
/*
|
|
* free_ipcs - free all ipcs of one type
|
|
* @ns: the namespace to remove the ipcs from
|
|
* @ids: the table of ipcs to free
|
|
* @free: the function called to free each individual ipc
|
|
*
|
|
* Called for each kind of ipc when an ipc_namespace exits.
|
|
*/
|
|
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
|
|
void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
|
|
{
|
|
struct kern_ipc_perm *perm;
|
|
int next_id;
|
|
int total, in_use;
|
|
|
|
down_write(&ids->rw_mutex);
|
|
|
|
in_use = ids->in_use;
|
|
|
|
for (total = 0, next_id = 0; total < in_use; next_id++) {
|
|
perm = idr_find(&ids->ipcs_idr, next_id);
|
|
if (perm == NULL)
|
|
continue;
|
|
ipc_lock_by_ptr(perm);
|
|
free(ns, perm);
|
|
total++;
|
|
}
|
|
up_write(&ids->rw_mutex);
|
|
}
|
|
|
|
static void free_ipc_ns(struct ipc_namespace *ns)
|
|
{
|
|
/*
|
|
* Unregistering the hotplug notifier at the beginning guarantees
|
|
* that the ipc namespace won't be freed while we are inside the
|
|
* callback routine. Since the blocking_notifier_chain_XXX routines
|
|
* hold a rw lock on the notifier list, unregister_ipcns_notifier()
|
|
* won't take the rw lock before blocking_notifier_call_chain() has
|
|
* released the rd lock.
|
|
*/
|
|
unregister_ipcns_notifier(ns);
|
|
sem_exit_ns(ns);
|
|
msg_exit_ns(ns);
|
|
shm_exit_ns(ns);
|
|
kfree(ns);
|
|
atomic_dec(&nr_ipc_ns);
|
|
|
|
/*
|
|
* Do the ipcns removal notification after decrementing nr_ipc_ns in
|
|
* order to have a correct value when recomputing msgmni.
|
|
*/
|
|
ipcns_notify(IPCNS_REMOVED);
|
|
}
|
|
|
|
/*
|
|
* put_ipc_ns - drop a reference to an ipc namespace.
|
|
* @ns: the namespace to put
|
|
*
|
|
* If this is the last task in the namespace exiting, and
|
|
* it is dropping the refcount to 0, then it can race with
|
|
* a task in another ipc namespace but in a mounts namespace
|
|
* which has this ipcns's mqueuefs mounted, doing some action
|
|
* with one of the mqueuefs files. That can raise the refcount.
|
|
* So dropping the refcount, and raising the refcount when
|
|
* accessing it through the VFS, are protected with mq_lock.
|
|
*
|
|
* (Clearly, a task raising the refcount on its own ipc_ns
|
|
* needn't take mq_lock since it can't race with the last task
|
|
* in the ipcns exiting).
|
|
*/
|
|
void put_ipc_ns(struct ipc_namespace *ns)
|
|
{
|
|
if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
|
|
mq_clear_sbinfo(ns);
|
|
spin_unlock(&mq_lock);
|
|
mq_put_mnt(ns);
|
|
free_ipc_ns(ns);
|
|
}
|
|
}
|