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/*
  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)->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};