// SPDX-License-Identifier: GPL-2.0/* * 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/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" static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns){	return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);} static void dec_ipc_namespaces(struct ucounts *ucounts){	dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);} static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,					   struct ipc_namespace *old_ns){	struct ipc_namespace *ns;	struct ucounts *ucounts;	int err; 	err = -ENOSPC;	ucounts = inc_ipc_namespaces(user_ns);	if (!ucounts)		goto fail; 	err = -ENOMEM;	ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL);	if (ns == NULL)		goto fail_dec; 	err = ns_alloc_inum(&ns->ns);	if (err)		goto fail_free;	ns->ns.ops = &ipcns_operations; 	refcount_set(&ns->count, 1);	ns->user_ns = get_user_ns(user_ns);	ns->ucounts = ucounts; 	err = mq_init_ns(ns);	if (err)		goto fail_put; 	sem_init_ns(ns);	msg_init_ns(ns);	shm_init_ns(ns); 	return ns; fail_put:	put_user_ns(ns->user_ns);	ns_free_inum(&ns->ns);fail_free:	kfree(ns);fail_dec:	dec_ipc_namespaces(ucounts);fail:	return ERR_PTR(err);} struct ipc_namespace *copy_ipcs(unsigned long flags,	struct user_namespace *user_ns, struct ipc_namespace *ns){	if (!(flags & CLONE_NEWIPC))		return get_ipc_ns(ns);	return create_ipc_ns(user_ns, 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->rwsem); 	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;		rcu_read_lock();		ipc_lock_object(perm);		free(ns, perm);		total++;	}	up_write(&ids->rwsem);} static void free_ipc_ns(struct ipc_namespace *ns){	sem_exit_ns(ns);	msg_exit_ns(ns);	shm_exit_ns(ns); 	dec_ipc_namespaces(ns->ucounts);	put_user_ns(ns->user_ns);	ns_free_inum(&ns->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 (refcount_dec_and_lock(&ns->count, &mq_lock)) {		mq_clear_sbinfo(ns);		spin_unlock(&mq_lock);		mq_put_mnt(ns);		free_ipc_ns(ns);	}} static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns){	return container_of(ns, struct ipc_namespace, ns);} static struct ns_common *ipcns_get(struct task_struct *task){	struct ipc_namespace *ns = NULL;	struct nsproxy *nsproxy; 	task_lock(task);	nsproxy = task->nsproxy;	if (nsproxy)		ns = get_ipc_ns(nsproxy->ipc_ns);	task_unlock(task); 	return ns ? &ns->ns : NULL;} static void ipcns_put(struct ns_common *ns){	return put_ipc_ns(to_ipc_ns(ns));} static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new){	struct ipc_namespace *ns = to_ipc_ns(new);	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))		return -EPERM; 	/* 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;} static struct user_namespace *ipcns_owner(struct ns_common *ns){	return to_ipc_ns(ns)->user_ns;} const struct proc_ns_operations ipcns_operations = {	.name		= "ipc",	.type		= CLONE_NEWIPC,	.get		= ipcns_get,	.put		= ipcns_put,	.install	= ipcns_install,	.owner		= ipcns_owner,};