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ae5e1b22 PE |
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> | |
7eafd7c7 SH |
12 | #include <linux/fs.h> |
13 | #include <linux/mount.h> | |
ae5e1b22 PE |
14 | |
15 | #include "util.h" | |
16 | ||
17 | static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns) | |
18 | { | |
ae5e1b22 | 19 | struct ipc_namespace *ns; |
7eafd7c7 | 20 | int err; |
ae5e1b22 | 21 | |
ae5e1b22 PE |
22 | ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL); |
23 | if (ns == NULL) | |
ed2ddbf8 | 24 | return ERR_PTR(-ENOMEM); |
ae5e1b22 | 25 | |
7eafd7c7 SH |
26 | atomic_set(&ns->count, 1); |
27 | err = mq_init_ns(ns); | |
28 | if (err) { | |
29 | kfree(ns); | |
30 | return ERR_PTR(err); | |
31 | } | |
4d89dc6a ND |
32 | atomic_inc(&nr_ipc_ns); |
33 | ||
ed2ddbf8 PP |
34 | sem_init_ns(ns); |
35 | msg_init_ns(ns); | |
36 | shm_init_ns(ns); | |
ae5e1b22 | 37 | |
e2c284d8 ND |
38 | /* |
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); | |
b6b337ad ND |
44 | register_ipcns_notifier(ns); |
45 | ||
ae5e1b22 | 46 | return ns; |
ae5e1b22 PE |
47 | } |
48 | ||
49 | struct 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 | ||
01b8b07a PP |
65 | /* |
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 | */ | |
73 | void 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 | ||
7eafd7c7 SH |
95 | /* |
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 | */ | |
111 | void put_ipc_ns(struct ipc_namespace *ns) | |
ae5e1b22 | 112 | { |
7eafd7c7 SH |
113 | 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 | } | |
ae5e1b22 | 120 | |
7eafd7c7 SH |
121 | void free_ipc_ns(struct ipc_namespace *ns) |
122 | { | |
b6b337ad ND |
123 | /* |
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); | |
ae5e1b22 PE |
132 | sem_exit_ns(ns); |
133 | msg_exit_ns(ns); | |
134 | shm_exit_ns(ns); | |
135 | kfree(ns); | |
4d89dc6a | 136 | atomic_dec(&nr_ipc_ns); |
e2c284d8 ND |
137 | |
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); | |
ae5e1b22 | 143 | } |