blob: f362298c5ce465e3585dfd2cbfdd528e29e4790d [file] [log] [blame]
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001/*
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>
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -070012#include <linux/fs.h>
13#include <linux/mount.h>
Serge E. Hallynb5154982011-03-23 16:43:23 -070014#include <linux/user_namespace.h>
Eric W. Biedermana00eaf12010-03-07 18:48:39 -080015#include <linux/proc_fs.h>
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080016
17#include "util.h"
18
Serge E. Hallynb0e77592011-03-23 16:43:24 -070019static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
20 struct ipc_namespace *old_ns)
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080021{
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080022 struct ipc_namespace *ns;
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -070023 int err;
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080024
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080025 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
26 if (ns == NULL)
Pierre Peiffered2ddbf2008-02-08 04:18:57 -080027 return ERR_PTR(-ENOMEM);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080028
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -070029 atomic_set(&ns->count, 1);
30 err = mq_init_ns(ns);
31 if (err) {
32 kfree(ns);
33 return ERR_PTR(err);
34 }
Nadia Derbey4d89dc62008-04-29 01:00:40 -070035 atomic_inc(&nr_ipc_ns);
36
Pierre Peiffered2ddbf2008-02-08 04:18:57 -080037 sem_init_ns(ns);
38 msg_init_ns(ns);
39 shm_init_ns(ns);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080040
Nadia Derbeye2c284d2008-04-29 01:00:44 -070041 /*
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);
Nadia Derbeyb6b337a2008-04-29 01:00:42 -070047 register_ipcns_notifier(ns);
48
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -080049 ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
Serge E. Hallynb5154982011-03-23 16:43:23 -070050
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080051 return ns;
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080052}
53
Serge E. Hallynb0e77592011-03-23 16:43:24 -070054struct ipc_namespace *copy_ipcs(unsigned long flags,
55 struct task_struct *tsk)
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080056{
Serge E. Hallynb0e77592011-03-23 16:43:24 -070057 struct ipc_namespace *ns = tsk->nsproxy->ipc_ns;
58
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080059 if (!(flags & CLONE_NEWIPC))
Alexey Dobriyan64424282009-06-17 16:27:54 -070060 return get_ipc_ns(ns);
Serge E. Hallynb0e77592011-03-23 16:43:24 -070061 return create_ipc_ns(tsk, ns);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080062}
63
Pierre Peiffer01b8b072008-02-08 04:18:57 -080064/*
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
Alexey Dobriyanb4188de2009-06-17 16:27:56 -070094static 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);
Alexey Dobriyanb4188de2009-06-17 16:27:56 -0700108 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);
Serge E. Hallynb5154982011-03-23 16:43:23 -0700115 put_user_ns(ns->user_ns);
Xiaotian Fengbe4d2502011-03-25 01:57:01 -0700116 kfree(ns);
Alexey Dobriyanb4188de2009-06-17 16:27:56 -0700117}
118
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -0700119/*
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)
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800136{
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -0700137 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}
Eric W. Biedermana00eaf12010-03-07 18:48:39 -0800144
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};