linux/ipc/namespace.c

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/ipc/namespace.c
 * Copyright (C) 2006 Pavel Emelyanov <[email protected]> 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/cred.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/user_namespace.h>
#include <linux/proc_ns.h>
#include <linux/sched/task.h>

#include "util.h"

/*
 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
 */
static void free_ipc(struct work_struct *unused);
static DECLARE_WORK(free_ipc_work, free_ipc);

static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
{ … }

static void dec_ipc_namespaces(struct ucounts *ucounts)
{ … }

static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
					   struct ipc_namespace *old_ns)
{ … }

struct ipc_namespace *copy_ipcs(unsigned long flags,
	struct user_namespace *user_ns, struct ipc_namespace *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 *))
{ … }

static void free_ipc_ns(struct ipc_namespace *ns)
{ … }

static LLIST_HEAD(free_ipc_list);
static void free_ipc(struct work_struct *unused)
{ … }

/*
 * 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)
{ … }

static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
{ … }

static struct ns_common *ipcns_get(struct task_struct *task)
{ … }

static void ipcns_put(struct ns_common *ns)
{ … }

static int ipcns_install(struct nsset *nsset, struct ns_common *new)
{ … }

static struct user_namespace *ipcns_owner(struct ns_common *ns)
{ … }

const struct proc_ns_operations ipcns_operations = …;