/* * 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 <linux/user_namespace.h>#include <linux/proc_fs.h> #include "util.h" static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,					   struct ipc_namespace *old_ns){	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); 	ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns); 	return ns;} struct ipc_namespace *copy_ipcs(unsigned long flags,				struct task_struct *tsk){	struct ipc_namespace *ns = tsk->nsproxy->ipc_ns; 	if (!(flags & CLONE_NEWIPC))		return get_ipc_ns(ns);	return create_ipc_ns(tsk, 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);	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_user_ns(ns->user_ns);	kfree(ns);} /* * 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);	}} static void *ipcns_get(struct task_struct *task){	struct ipc_namespace *ns = NULL;	struct nsproxy *nsproxy; 	rcu_read_lock();	nsproxy = task_nsproxy(task);	if (nsproxy)		ns = get_ipc_ns(nsproxy->ipc_ns);	rcu_read_unlock(); 	return ns;} static void ipcns_put(void *ns){	return put_ipc_ns(ns);} static int ipcns_install(struct nsproxy *nsproxy, void *ns){	/* Ditch state from the old ipc namespace */	exit_sem(current);	put_ipc_ns(nsproxy->ipc_ns);	nsproxy->ipc_ns = get_ipc_ns(ns);	return 0;} const struct proc_ns_operations ipcns_operations = {	.name		= "ipc",	.type		= CLONE_NEWIPC,	.get		= ipcns_get,	.put		= ipcns_put,	.install	= ipcns_install,};