blob: 4a5e752a92766d6e578c5c94499bdd71e60cbaf5 [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>
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080014
15#include "util.h"
16
17static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
18{
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080019 struct ipc_namespace *ns;
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -070020 int err;
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080021
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080022 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
23 if (ns == NULL)
Pierre Peiffered2ddbf2008-02-08 04:18:57 -080024 return ERR_PTR(-ENOMEM);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080025
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -070026 atomic_set(&ns->count, 1);
27 err = mq_init_ns(ns);
28 if (err) {
29 kfree(ns);
30 return ERR_PTR(err);
31 }
Nadia Derbey4d89dc62008-04-29 01:00:40 -070032 atomic_inc(&nr_ipc_ns);
33
Pierre Peiffered2ddbf2008-02-08 04:18:57 -080034 sem_init_ns(ns);
35 msg_init_ns(ns);
36 shm_init_ns(ns);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080037
Nadia Derbeye2c284d2008-04-29 01:00:44 -070038 /*
39 * msgmni has already been computed for the new ipc ns.
40 * Thus, do the ipcns creation notification before registering that
41 * new ipcns in the chain.
42 */
43 ipcns_notify(IPCNS_CREATED);
Nadia Derbeyb6b337a2008-04-29 01:00:42 -070044 register_ipcns_notifier(ns);
45
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080046 return ns;
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080047}
48
49struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
50{
51 struct ipc_namespace *new_ns;
52
53 BUG_ON(!ns);
54 get_ipc_ns(ns);
55
56 if (!(flags & CLONE_NEWIPC))
57 return ns;
58
59 new_ns = clone_ipc_ns(ns);
60
61 put_ipc_ns(ns);
62 return new_ns;
63}
64
Pierre Peiffer01b8b072008-02-08 04:18:57 -080065/*
66 * free_ipcs - free all ipcs of one type
67 * @ns: the namespace to remove the ipcs from
68 * @ids: the table of ipcs to free
69 * @free: the function called to free each individual ipc
70 *
71 * Called for each kind of ipc when an ipc_namespace exits.
72 */
73void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
74 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
75{
76 struct kern_ipc_perm *perm;
77 int next_id;
78 int total, in_use;
79
80 down_write(&ids->rw_mutex);
81
82 in_use = ids->in_use;
83
84 for (total = 0, next_id = 0; total < in_use; next_id++) {
85 perm = idr_find(&ids->ipcs_idr, next_id);
86 if (perm == NULL)
87 continue;
88 ipc_lock_by_ptr(perm);
89 free(ns, perm);
90 total++;
91 }
92 up_write(&ids->rw_mutex);
93}
94
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -070095/*
96 * put_ipc_ns - drop a reference to an ipc namespace.
97 * @ns: the namespace to put
98 *
99 * If this is the last task in the namespace exiting, and
100 * it is dropping the refcount to 0, then it can race with
101 * a task in another ipc namespace but in a mounts namespace
102 * which has this ipcns's mqueuefs mounted, doing some action
103 * with one of the mqueuefs files. That can raise the refcount.
104 * So dropping the refcount, and raising the refcount when
105 * accessing it through the VFS, are protected with mq_lock.
106 *
107 * (Clearly, a task raising the refcount on its own ipc_ns
108 * needn't take mq_lock since it can't race with the last task
109 * in the ipcns exiting).
110 */
111void put_ipc_ns(struct ipc_namespace *ns)
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800112{
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -0700113 if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
114 mq_clear_sbinfo(ns);
115 spin_unlock(&mq_lock);
116 mq_put_mnt(ns);
117 free_ipc_ns(ns);
118 }
119}
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800120
Serge E. Hallyn7eafd7c2009-04-06 19:01:10 -0700121void free_ipc_ns(struct ipc_namespace *ns)
122{
Nadia Derbeyb6b337a2008-04-29 01:00:42 -0700123 /*
124 * Unregistering the hotplug notifier at the beginning guarantees
125 * that the ipc namespace won't be freed while we are inside the
126 * callback routine. Since the blocking_notifier_chain_XXX routines
127 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
128 * won't take the rw lock before blocking_notifier_call_chain() has
129 * released the rd lock.
130 */
131 unregister_ipcns_notifier(ns);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800132 sem_exit_ns(ns);
133 msg_exit_ns(ns);
134 shm_exit_ns(ns);
135 kfree(ns);
Nadia Derbey4d89dc62008-04-29 01:00:40 -0700136 atomic_dec(&nr_ipc_ns);
Nadia Derbeye2c284d2008-04-29 01:00:44 -0700137
138 /*
139 * Do the ipcns removal notification after decrementing nr_ipc_ns in
140 * order to have a correct value when recomputing msgmni.
141 */
142 ipcns_notify(IPCNS_REMOVED);
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800143}