1/*
  2 * linux/ipc/namespace.c
  3 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
  4 */
  5
  6#include <linux/ipc.h>
  7#include <linux/msg.h>
  8#include <linux/ipc_namespace.h>
  9#include <linux/rcupdate.h>
 10#include <linux/nsproxy.h>
 11#include <linux/slab.h>
 
 12#include <linux/fs.h>
 13#include <linux/mount.h>
 14#include <linux/user_namespace.h>
 15#include <linux/proc_fs.h>
 
 16
 17#include "util.h"
 18
 19static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
 
 
 
 
 
 
 
 
 
 
 20					   struct ipc_namespace *old_ns)
 21{
 22	struct ipc_namespace *ns;
 
 23	int err;
 24
 25	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
 
 
 
 
 
 
 26	if (ns == NULL)
 27		return ERR_PTR(-ENOMEM);
 
 
 
 
 
 
 
 
 
 28
 29	atomic_set(&ns->count, 1);
 30	err = mq_init_ns(ns);
 31	if (err) {
 32		kfree(ns);
 33		return ERR_PTR(err);
 34	}
 35	atomic_inc(&nr_ipc_ns);
 36
 37	sem_init_ns(ns);
 38	msg_init_ns(ns);
 39	shm_init_ns(ns);
 40
 41	/*
 42	 * msgmni has already been computed for the new ipc ns.
 43	 * Thus, do the ipcns creation notification before registering that
 44	 * new ipcns in the chain.
 45	 */
 46	ipcns_notify(IPCNS_CREATED);
 47	register_ipcns_notifier(ns);
 48
 49	ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
 50
 51	return ns;
 
 
 
 
 
 
 
 
 
 
 52}
 53
 54struct ipc_namespace *copy_ipcs(unsigned long flags,
 55				struct task_struct *tsk)
 56{
 57	struct ipc_namespace *ns = tsk->nsproxy->ipc_ns;
 58
 59	if (!(flags & CLONE_NEWIPC))
 60		return get_ipc_ns(ns);
 61	return create_ipc_ns(tsk, ns);
 62}
 63
 64/*
 65 * free_ipcs - free all ipcs of one type
 66 * @ns:   the namespace to remove the ipcs from
 67 * @ids:  the table of ipcs to free
 68 * @free: the function called to free each individual ipc
 69 *
 70 * Called for each kind of ipc when an ipc_namespace exits.
 71 */
 72void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 73	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
 74{
 75	struct kern_ipc_perm *perm;
 76	int next_id;
 77	int total, in_use;
 78
 79	down_write(&ids->rw_mutex);
 80
 81	in_use = ids->in_use;
 82
 83	for (total = 0, next_id = 0; total < in_use; next_id++) {
 84		perm = idr_find(&ids->ipcs_idr, next_id);
 85		if (perm == NULL)
 86			continue;
 87		ipc_lock_by_ptr(perm);
 
 88		free(ns, perm);
 89		total++;
 90	}
 91	up_write(&ids->rw_mutex);
 92}
 93
 94static void free_ipc_ns(struct ipc_namespace *ns)
 95{
 96	/*
 97	 * Unregistering the hotplug notifier at the beginning guarantees
 98	 * that the ipc namespace won't be freed while we are inside the
 99	 * callback routine. Since the blocking_notifier_chain_XXX routines
100	 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
101	 * won't take the rw lock before blocking_notifier_call_chain() has
102	 * released the rd lock.
103	 */
104	unregister_ipcns_notifier(ns);
105	sem_exit_ns(ns);
106	msg_exit_ns(ns);
107	shm_exit_ns(ns);
108	atomic_dec(&nr_ipc_ns);
109
110	/*
111	 * Do the ipcns removal notification after decrementing nr_ipc_ns in
112	 * order to have a correct value when recomputing msgmni.
113	 */
114	ipcns_notify(IPCNS_REMOVED);
115	put_user_ns(ns->user_ns);
 
116	kfree(ns);
117}
118
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
119/*
120 * put_ipc_ns - drop a reference to an ipc namespace.
121 * @ns: the namespace to put
122 *
123 * If this is the last task in the namespace exiting, and
124 * it is dropping the refcount to 0, then it can race with
125 * a task in another ipc namespace but in a mounts namespace
126 * which has this ipcns's mqueuefs mounted, doing some action
127 * with one of the mqueuefs files.  That can raise the refcount.
128 * So dropping the refcount, and raising the refcount when
129 * accessing it through the VFS, are protected with mq_lock.
130 *
131 * (Clearly, a task raising the refcount on its own ipc_ns
132 * needn't take mq_lock since it can't race with the last task
133 * in the ipcns exiting).
134 */
135void put_ipc_ns(struct ipc_namespace *ns)
136{
137	if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
138		mq_clear_sbinfo(ns);
139		spin_unlock(&mq_lock);
140		mq_put_mnt(ns);
141		free_ipc_ns(ns);
 
142	}
143}
144
145static void *ipcns_get(struct task_struct *task)
 
 
 
 
 
146{
147	struct ipc_namespace *ns = NULL;
148	struct nsproxy *nsproxy;
149
150	rcu_read_lock();
151	nsproxy = task_nsproxy(task);
152	if (nsproxy)
153		ns = get_ipc_ns(nsproxy->ipc_ns);
154	rcu_read_unlock();
155
156	return ns;
157}
158
159static void ipcns_put(void *ns)
160{
161	return put_ipc_ns(ns);
162}
163
164static int ipcns_install(struct nsproxy *nsproxy, void *ns)
165{
166	/* Ditch state from the old ipc namespace */
167	exit_sem(current);
 
 
 
 
168	put_ipc_ns(nsproxy->ipc_ns);
169	nsproxy->ipc_ns = get_ipc_ns(ns);
170	return 0;
171}
172
 
 
 
 
 
173const struct proc_ns_operations ipcns_operations = {
174	.name		= "ipc",
175	.type		= CLONE_NEWIPC,
176	.get		= ipcns_get,
177	.put		= ipcns_put,
178	.install	= ipcns_install,
 
179};

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * linux/ipc/namespace.c
  4 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
  5 */
  6
  7#include <linux/ipc.h>
  8#include <linux/msg.h>
  9#include <linux/ipc_namespace.h>
 10#include <linux/rcupdate.h>
 11#include <linux/nsproxy.h>
 12#include <linux/slab.h>
 13#include <linux/cred.h>
 14#include <linux/fs.h>
 15#include <linux/mount.h>
 16#include <linux/user_namespace.h>
 17#include <linux/proc_ns.h>
 18#include <linux/sched/task.h>
 19
 20#include "util.h"
 21
 22static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
 23{
 24	return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
 25}
 26
 27static void dec_ipc_namespaces(struct ucounts *ucounts)
 28{
 29	dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
 30}
 31
 32static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 33					   struct ipc_namespace *old_ns)
 34{
 35	struct ipc_namespace *ns;
 36	struct ucounts *ucounts;
 37	int err;
 38
 39	err = -ENOSPC;
 40	ucounts = inc_ipc_namespaces(user_ns);
 41	if (!ucounts)
 42		goto fail;
 43
 44	err = -ENOMEM;
 45	ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
 46	if (ns == NULL)
 47		goto fail_dec;
 48
 49	err = ns_alloc_inum(&ns->ns);
 50	if (err)
 51		goto fail_free;
 52	ns->ns.ops = &ipcns_operations;
 53
 54	refcount_set(&ns->ns.count, 1);
 55	ns->user_ns = get_user_ns(user_ns);
 56	ns->ucounts = ucounts;
 57
 
 58	err = mq_init_ns(ns);
 59	if (err)
 60		goto fail_put;
 
 
 
 61
 62	sem_init_ns(ns);
 63	msg_init_ns(ns);
 64	shm_init_ns(ns);
 65
 
 
 
 
 
 
 
 
 
 
 66	return ns;
 67
 68fail_put:
 69	put_user_ns(ns->user_ns);
 70	ns_free_inum(&ns->ns);
 71fail_free:
 72	kfree(ns);
 73fail_dec:
 74	dec_ipc_namespaces(ucounts);
 75fail:
 76	return ERR_PTR(err);
 77}
 78
 79struct ipc_namespace *copy_ipcs(unsigned long flags,
 80	struct user_namespace *user_ns, struct ipc_namespace *ns)
 81{
 
 
 82	if (!(flags & CLONE_NEWIPC))
 83		return get_ipc_ns(ns);
 84	return create_ipc_ns(user_ns, ns);
 85}
 86
 87/*
 88 * free_ipcs - free all ipcs of one type
 89 * @ns:   the namespace to remove the ipcs from
 90 * @ids:  the table of ipcs to free
 91 * @free: the function called to free each individual ipc
 92 *
 93 * Called for each kind of ipc when an ipc_namespace exits.
 94 */
 95void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 96	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
 97{
 98	struct kern_ipc_perm *perm;
 99	int next_id;
100	int total, in_use;
101
102	down_write(&ids->rwsem);
103
104	in_use = ids->in_use;
105
106	for (total = 0, next_id = 0; total < in_use; next_id++) {
107		perm = idr_find(&ids->ipcs_idr, next_id);
108		if (perm == NULL)
109			continue;
110		rcu_read_lock();
111		ipc_lock_object(perm);
112		free(ns, perm);
113		total++;
114	}
115	up_write(&ids->rwsem);
116}
117
118static void free_ipc_ns(struct ipc_namespace *ns)
119{
120	/* mq_put_mnt() waits for a grace period as kern_unmount()
121	 * uses synchronize_rcu().
 
 
 
 
 
122	 */
123	mq_put_mnt(ns);
124	sem_exit_ns(ns);
125	msg_exit_ns(ns);
126	shm_exit_ns(ns);
 
127
128	dec_ipc_namespaces(ns->ucounts);
 
 
 
 
129	put_user_ns(ns->user_ns);
130	ns_free_inum(&ns->ns);
131	kfree(ns);
132}
133
134static LLIST_HEAD(free_ipc_list);
135static void free_ipc(struct work_struct *unused)
136{
137	struct llist_node *node = llist_del_all(&free_ipc_list);
138	struct ipc_namespace *n, *t;
139
140	llist_for_each_entry_safe(n, t, node, mnt_llist)
141		free_ipc_ns(n);
142}
143
144/*
145 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
146 */
147static DECLARE_WORK(free_ipc_work, free_ipc);
148
149/*
150 * put_ipc_ns - drop a reference to an ipc namespace.
151 * @ns: the namespace to put
152 *
153 * If this is the last task in the namespace exiting, and
154 * it is dropping the refcount to 0, then it can race with
155 * a task in another ipc namespace but in a mounts namespace
156 * which has this ipcns's mqueuefs mounted, doing some action
157 * with one of the mqueuefs files.  That can raise the refcount.
158 * So dropping the refcount, and raising the refcount when
159 * accessing it through the VFS, are protected with mq_lock.
160 *
161 * (Clearly, a task raising the refcount on its own ipc_ns
162 * needn't take mq_lock since it can't race with the last task
163 * in the ipcns exiting).
164 */
165void put_ipc_ns(struct ipc_namespace *ns)
166{
167	if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
168		mq_clear_sbinfo(ns);
169		spin_unlock(&mq_lock);
170
171		if (llist_add(&ns->mnt_llist, &free_ipc_list))
172			schedule_work(&free_ipc_work);
173	}
174}
175
176static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
177{
178	return container_of(ns, struct ipc_namespace, ns);
179}
180
181static struct ns_common *ipcns_get(struct task_struct *task)
182{
183	struct ipc_namespace *ns = NULL;
184	struct nsproxy *nsproxy;
185
186	task_lock(task);
187	nsproxy = task->nsproxy;
188	if (nsproxy)
189		ns = get_ipc_ns(nsproxy->ipc_ns);
190	task_unlock(task);
191
192	return ns ? &ns->ns : NULL;
193}
194
195static void ipcns_put(struct ns_common *ns)
196{
197	return put_ipc_ns(to_ipc_ns(ns));
198}
199
200static int ipcns_install(struct nsset *nsset, struct ns_common *new)
201{
202	struct nsproxy *nsproxy = nsset->nsproxy;
203	struct ipc_namespace *ns = to_ipc_ns(new);
204	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
205	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
206		return -EPERM;
207
208	put_ipc_ns(nsproxy->ipc_ns);
209	nsproxy->ipc_ns = get_ipc_ns(ns);
210	return 0;
211}
212
213static struct user_namespace *ipcns_owner(struct ns_common *ns)
214{
215	return to_ipc_ns(ns)->user_ns;
216}
217
218const struct proc_ns_operations ipcns_operations = {
219	.name		= "ipc",
220	.type		= CLONE_NEWIPC,
221	.get		= ipcns_get,
222	.put		= ipcns_put,
223	.install	= ipcns_install,
224	.owner		= ipcns_owner,
225};