// 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/nstree.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){	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; again:	ucounts = inc_ipc_namespaces(user_ns);	if (!ucounts) {		/*		 * IPC namespaces are freed asynchronously, by free_ipc_work.		 * If frees were pending, flush_work will wait, and		 * return true. Fail the allocation if no frees are pending.		 */		if (flush_work(&free_ipc_work))			goto again;		goto fail;	} 	err = -ENOMEM;	ns = kzalloc_obj(struct ipc_namespace, GFP_KERNEL_ACCOUNT);	if (ns == NULL)		goto fail_dec; 	err = ns_common_init(ns);	if (err)		goto fail_free; 	ns_tree_gen_id(ns);	ns->user_ns = get_user_ns(user_ns);	ns->ucounts = ucounts; 	err = mq_init_ns(ns);	if (err)		goto fail_put; 	err = -ENOMEM;	if (!setup_mq_sysctls(ns))		goto fail_mq_mount; 	if (!setup_ipc_sysctls(ns))		goto fail_mq_sysctls; 	err = msg_init_ns(ns);	if (err)		goto fail_ipc; 	sem_init_ns(ns);	shm_init_ns(ns);	ns_tree_add_raw(ns); 	return ns; fail_ipc:	retire_ipc_sysctls(ns);fail_mq_sysctls:	retire_mq_sysctls(ns);fail_mq_mount:	mntput(ns->mq_mnt);fail_put:	put_user_ns(ns->user_ns);	ns_common_free(ns);fail_free:	kfree(ns);fail_dec:	dec_ipc_namespaces(ucounts);fail:	return ERR_PTR(err);} struct ipc_namespace *copy_ipcs(u64 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){	/*	 * Caller needs to wait for an RCU grace period to have passed	 * after making the mount point inaccessible to new accesses.	 */	mntput(ns->mq_mnt);	sem_exit_ns(ns);	msg_exit_ns(ns);	shm_exit_ns(ns); 	retire_mq_sysctls(ns);	retire_ipc_sysctls(ns); 	dec_ipc_namespaces(ns->ucounts);	put_user_ns(ns->user_ns);	ns_common_free(ns);	kfree(ns);} static LLIST_HEAD(free_ipc_list);static void free_ipc(struct work_struct *unused){	struct llist_node *node = llist_del_all(&free_ipc_list);	struct ipc_namespace *n, *t; 	llist_for_each_entry_safe(n, t, node, mnt_llist)		mnt_make_shortterm(n->mq_mnt); 	/* Wait for any last users to have gone away. */	synchronize_rcu(); 	llist_for_each_entry_safe(n, t, node, mnt_llist)		free_ipc_ns(n);} /* * 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 (ns_ref_put_and_lock(ns, &mq_lock)) {		mq_clear_sbinfo(ns);		spin_unlock(&mq_lock); 		ns_tree_remove(ns);		if (llist_add(&ns->mnt_llist, &free_ipc_list))			schedule_work(&free_ipc_work);	}} 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 nsset *nsset, struct ns_common *new){	struct nsproxy *nsproxy = nsset->nsproxy;	struct ipc_namespace *ns = to_ipc_ns(new);	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))		return -EPERM; 	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",	.get		= ipcns_get,	.put		= ipcns_put,	.install	= ipcns_install,	.owner		= ipcns_owner,};