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
13 #include "util.h"
14
clone_ipc_ns(struct ipc_namespace * old_ns)15 static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
16 {
17 struct ipc_namespace *ns;
18
19 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
20 if (ns == NULL)
21 return ERR_PTR(-ENOMEM);
22
23 atomic_inc(&nr_ipc_ns);
24
25 sem_init_ns(ns);
26 msg_init_ns(ns);
27 shm_init_ns(ns);
28
29 /*
30 * msgmni has already been computed for the new ipc ns.
31 * Thus, do the ipcns creation notification before registering that
32 * new ipcns in the chain.
33 */
34 ipcns_notify(IPCNS_CREATED);
35 register_ipcns_notifier(ns);
36
37 kref_init(&ns->kref);
38 return ns;
39 }
40
copy_ipcs(unsigned long flags,struct ipc_namespace * ns)41 struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
42 {
43 struct ipc_namespace *new_ns;
44
45 BUG_ON(!ns);
46 get_ipc_ns(ns);
47
48 if (!(flags & CLONE_NEWIPC))
49 return ns;
50
51 new_ns = clone_ipc_ns(ns);
52
53 put_ipc_ns(ns);
54 return new_ns;
55 }
56
57 /*
58 * free_ipcs - free all ipcs of one type
59 * @ns: the namespace to remove the ipcs from
60 * @ids: the table of ipcs to free
61 * @free: the function called to free each individual ipc
62 *
63 * Called for each kind of ipc when an ipc_namespace exits.
64 */
free_ipcs(struct ipc_namespace * ns,struct ipc_ids * ids,void (* free)(struct ipc_namespace *,struct kern_ipc_perm *))65 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
66 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
67 {
68 struct kern_ipc_perm *perm;
69 int next_id;
70 int total, in_use;
71
72 down_write(&ids->rw_mutex);
73
74 in_use = ids->in_use;
75
76 for (total = 0, next_id = 0; total < in_use; next_id++) {
77 perm = idr_find(&ids->ipcs_idr, next_id);
78 if (perm == NULL)
79 continue;
80 ipc_lock_by_ptr(perm);
81 free(ns, perm);
82 total++;
83 }
84 up_write(&ids->rw_mutex);
85 }
86
free_ipc_ns(struct kref * kref)87 void free_ipc_ns(struct kref *kref)
88 {
89 struct ipc_namespace *ns;
90
91 ns = container_of(kref, struct ipc_namespace, kref);
92 /*
93 * Unregistering the hotplug notifier at the beginning guarantees
94 * that the ipc namespace won't be freed while we are inside the
95 * callback routine. Since the blocking_notifier_chain_XXX routines
96 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
97 * won't take the rw lock before blocking_notifier_call_chain() has
98 * released the rd lock.
99 */
100 unregister_ipcns_notifier(ns);
101 sem_exit_ns(ns);
102 msg_exit_ns(ns);
103 shm_exit_ns(ns);
104 kfree(ns);
105 atomic_dec(&nr_ipc_ns);
106
107 /*
108 * Do the ipcns removal notification after decrementing nr_ipc_ns in
109 * order to have a correct value when recomputing msgmni.
110 */
111 ipcns_notify(IPCNS_REMOVED);
112 }
113