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_ns.h>
 
 16
 17#include "util.h"
 18
 
 
 
 
 
 
 
 
 
 
 19static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 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	err = ns_alloc_inum(&ns->ns);
 30	if (err) {
 31		kfree(ns);
 32		return ERR_PTR(err);
 33	}
 34	ns->ns.ops = &ipcns_operations;
 35
 36	atomic_set(&ns->count, 1);
 
 
 
 37	err = mq_init_ns(ns);
 38	if (err) {
 39		ns_free_inum(&ns->ns);
 40		kfree(ns);
 41		return ERR_PTR(err);
 42	}
 43	atomic_inc(&nr_ipc_ns);
 44
 45	sem_init_ns(ns);
 46	msg_init_ns(ns);
 47	shm_init_ns(ns);
 48
 49	ns->user_ns = get_user_ns(user_ns);
 50
 51	return ns;
 
 
 
 
 
 
 
 
 
 
 52}
 53
 54struct ipc_namespace *copy_ipcs(unsigned long flags,
 55	struct user_namespace *user_ns, struct ipc_namespace *ns)
 56{
 57	if (!(flags & CLONE_NEWIPC))
 58		return get_ipc_ns(ns);
 59	return create_ipc_ns(user_ns, ns);
 60}
 61
 62/*
 63 * free_ipcs - free all ipcs of one type
 64 * @ns:   the namespace to remove the ipcs from
 65 * @ids:  the table of ipcs to free
 66 * @free: the function called to free each individual ipc
 67 *
 68 * Called for each kind of ipc when an ipc_namespace exits.
 69 */
 70void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 71	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
 72{
 73	struct kern_ipc_perm *perm;
 74	int next_id;
 75	int total, in_use;
 76
 77	down_write(&ids->rwsem);
 78
 79	in_use = ids->in_use;
 80
 81	for (total = 0, next_id = 0; total < in_use; next_id++) {
 82		perm = idr_find(&ids->ipcs_idr, next_id);
 83		if (perm == NULL)
 84			continue;
 85		rcu_read_lock();
 86		ipc_lock_object(perm);
 87		free(ns, perm);
 88		total++;
 89	}
 90	up_write(&ids->rwsem);
 91}
 92
 93static void free_ipc_ns(struct ipc_namespace *ns)
 94{
 
 
 
 
 95	sem_exit_ns(ns);
 96	msg_exit_ns(ns);
 97	shm_exit_ns(ns);
 98	atomic_dec(&nr_ipc_ns);
 99
 
100	put_user_ns(ns->user_ns);
101	ns_free_inum(&ns->ns);
102	kfree(ns);
103}
104
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
105/*
106 * put_ipc_ns - drop a reference to an ipc namespace.
107 * @ns: the namespace to put
108 *
109 * If this is the last task in the namespace exiting, and
110 * it is dropping the refcount to 0, then it can race with
111 * a task in another ipc namespace but in a mounts namespace
112 * which has this ipcns's mqueuefs mounted, doing some action
113 * with one of the mqueuefs files.  That can raise the refcount.
114 * So dropping the refcount, and raising the refcount when
115 * accessing it through the VFS, are protected with mq_lock.
116 *
117 * (Clearly, a task raising the refcount on its own ipc_ns
118 * needn't take mq_lock since it can't race with the last task
119 * in the ipcns exiting).
120 */
121void put_ipc_ns(struct ipc_namespace *ns)
122{
123	if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
124		mq_clear_sbinfo(ns);
125		spin_unlock(&mq_lock);
126		mq_put_mnt(ns);
127		free_ipc_ns(ns);
 
128	}
129}
130
131static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
132{
133	return container_of(ns, struct ipc_namespace, ns);
134}
135
136static struct ns_common *ipcns_get(struct task_struct *task)
137{
138	struct ipc_namespace *ns = NULL;
139	struct nsproxy *nsproxy;
140
141	task_lock(task);
142	nsproxy = task->nsproxy;
143	if (nsproxy)
144		ns = get_ipc_ns(nsproxy->ipc_ns);
145	task_unlock(task);
146
147	return ns ? &ns->ns : NULL;
148}
149
150static void ipcns_put(struct ns_common *ns)
151{
152	return put_ipc_ns(to_ipc_ns(ns));
153}
154
155static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
156{
 
157	struct ipc_namespace *ns = to_ipc_ns(new);
158	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
159	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
160		return -EPERM;
161
162	/* Ditch state from the old ipc namespace */
163	exit_sem(current);
164	put_ipc_ns(nsproxy->ipc_ns);
165	nsproxy->ipc_ns = get_ipc_ns(ns);
166	return 0;
167}
168
 
 
 
 
 
169const struct proc_ns_operations ipcns_operations = {
170	.name		= "ipc",
171	.type		= CLONE_NEWIPC,
172	.get		= ipcns_get,
173	.put		= ipcns_put,
174	.install	= ipcns_install,
 
175};

  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->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->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};