Commit | Line | Data |
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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> | |
b515498f | 14 | #include <linux/user_namespace.h> |
ae5e1b22 PE |
15 | |
16 | #include "util.h" | |
17 | ||
b0e77598 SH |
18 | static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk, |
19 | struct ipc_namespace *old_ns) | |
ae5e1b22 | 20 | { |
ae5e1b22 | 21 | struct ipc_namespace *ns; |
7eafd7c7 | 22 | int err; |
ae5e1b22 | 23 | |
ae5e1b22 PE |
24 | ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL); |
25 | if (ns == NULL) | |
ed2ddbf8 | 26 | return ERR_PTR(-ENOMEM); |
ae5e1b22 | 27 | |
7eafd7c7 SH |
28 | atomic_set(&ns->count, 1); |
29 | err = mq_init_ns(ns); | |
30 | if (err) { | |
31 | kfree(ns); | |
32 | return ERR_PTR(err); | |
33 | } | |
4d89dc6a ND |
34 | atomic_inc(&nr_ipc_ns); |
35 | ||
ed2ddbf8 PP |
36 | sem_init_ns(ns); |
37 | msg_init_ns(ns); | |
38 | shm_init_ns(ns); | |
ae5e1b22 | 39 | |
e2c284d8 ND |
40 | /* |
41 | * msgmni has already been computed for the new ipc ns. | |
42 | * Thus, do the ipcns creation notification before registering that | |
43 | * new ipcns in the chain. | |
44 | */ | |
45 | ipcns_notify(IPCNS_CREATED); | |
b6b337ad ND |
46 | register_ipcns_notifier(ns); |
47 | ||
b0e77598 | 48 | ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns); |
b515498f | 49 | |
ae5e1b22 | 50 | return ns; |
ae5e1b22 PE |
51 | } |
52 | ||
b0e77598 SH |
53 | struct ipc_namespace *copy_ipcs(unsigned long flags, |
54 | struct task_struct *tsk) | |
ae5e1b22 | 55 | { |
b0e77598 SH |
56 | struct ipc_namespace *ns = tsk->nsproxy->ipc_ns; |
57 | ||
ae5e1b22 | 58 | if (!(flags & CLONE_NEWIPC)) |
64424289 | 59 | return get_ipc_ns(ns); |
b0e77598 | 60 | return create_ipc_ns(tsk, ns); |
ae5e1b22 PE |
61 | } |
62 | ||
01b8b07a PP |
63 | /* |
64 | * free_ipcs - free all ipcs of one type | |
65 | * @ns: the namespace to remove the ipcs from | |
66 | * @ids: the table of ipcs to free | |
67 | * @free: the function called to free each individual ipc | |
68 | * | |
69 | * Called for each kind of ipc when an ipc_namespace exits. | |
70 | */ | |
71 | void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, | |
72 | void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)) | |
73 | { | |
74 | struct kern_ipc_perm *perm; | |
75 | int next_id; | |
76 | int total, in_use; | |
77 | ||
78 | down_write(&ids->rw_mutex); | |
79 | ||
80 | in_use = ids->in_use; | |
81 | ||
82 | for (total = 0, next_id = 0; total < in_use; next_id++) { | |
83 | perm = idr_find(&ids->ipcs_idr, next_id); | |
84 | if (perm == NULL) | |
85 | continue; | |
86 | ipc_lock_by_ptr(perm); | |
87 | free(ns, perm); | |
88 | total++; | |
89 | } | |
90 | up_write(&ids->rw_mutex); | |
91 | } | |
92 | ||
b4188def AD |
93 | static void free_ipc_ns(struct ipc_namespace *ns) |
94 | { | |
95 | /* | |
96 | * Unregistering the hotplug notifier at the beginning guarantees | |
97 | * that the ipc namespace won't be freed while we are inside the | |
98 | * callback routine. Since the blocking_notifier_chain_XXX routines | |
99 | * hold a rw lock on the notifier list, unregister_ipcns_notifier() | |
100 | * won't take the rw lock before blocking_notifier_call_chain() has | |
101 | * released the rd lock. | |
102 | */ | |
103 | unregister_ipcns_notifier(ns); | |
104 | sem_exit_ns(ns); | |
105 | msg_exit_ns(ns); | |
106 | shm_exit_ns(ns); | |
b4188def AD |
107 | atomic_dec(&nr_ipc_ns); |
108 | ||
109 | /* | |
110 | * Do the ipcns removal notification after decrementing nr_ipc_ns in | |
111 | * order to have a correct value when recomputing msgmni. | |
112 | */ | |
113 | ipcns_notify(IPCNS_REMOVED); | |
b515498f | 114 | put_user_ns(ns->user_ns); |
be4d250a | 115 | kfree(ns); |
b4188def AD |
116 | } |
117 | ||
7eafd7c7 SH |
118 | /* |
119 | * put_ipc_ns - drop a reference to an ipc namespace. | |
120 | * @ns: the namespace to put | |
121 | * | |
122 | * If this is the last task in the namespace exiting, and | |
123 | * it is dropping the refcount to 0, then it can race with | |
124 | * a task in another ipc namespace but in a mounts namespace | |
125 | * which has this ipcns's mqueuefs mounted, doing some action | |
126 | * with one of the mqueuefs files. That can raise the refcount. | |
127 | * So dropping the refcount, and raising the refcount when | |
128 | * accessing it through the VFS, are protected with mq_lock. | |
129 | * | |
130 | * (Clearly, a task raising the refcount on its own ipc_ns | |
131 | * needn't take mq_lock since it can't race with the last task | |
132 | * in the ipcns exiting). | |
133 | */ | |
134 | void put_ipc_ns(struct ipc_namespace *ns) | |
ae5e1b22 | 135 | { |
7eafd7c7 SH |
136 | if (atomic_dec_and_lock(&ns->count, &mq_lock)) { |
137 | mq_clear_sbinfo(ns); | |
138 | spin_unlock(&mq_lock); | |
139 | mq_put_mnt(ns); | |
140 | free_ipc_ns(ns); | |
141 | } | |
142 | } |