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> |
a00eaf11 | 15 | #include <linux/proc_fs.h> |
ae5e1b22 PE |
16 | |
17 | #include "util.h" | |
18 | ||
bcf58e72 | 19 | static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, |
b0e77598 | 20 | struct ipc_namespace *old_ns) |
ae5e1b22 | 21 | { |
ae5e1b22 | 22 | struct ipc_namespace *ns; |
7eafd7c7 | 23 | int err; |
ae5e1b22 | 24 | |
ae5e1b22 PE |
25 | ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL); |
26 | if (ns == NULL) | |
ed2ddbf8 | 27 | return ERR_PTR(-ENOMEM); |
ae5e1b22 | 28 | |
7eafd7c7 SH |
29 | atomic_set(&ns->count, 1); |
30 | err = mq_init_ns(ns); | |
31 | if (err) { | |
32 | kfree(ns); | |
33 | return ERR_PTR(err); | |
34 | } | |
4d89dc6a ND |
35 | atomic_inc(&nr_ipc_ns); |
36 | ||
ed2ddbf8 PP |
37 | sem_init_ns(ns); |
38 | msg_init_ns(ns); | |
39 | shm_init_ns(ns); | |
ae5e1b22 | 40 | |
e2c284d8 ND |
41 | /* |
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); | |
b6b337ad ND |
47 | register_ipcns_notifier(ns); |
48 | ||
bcf58e72 | 49 | ns->user_ns = get_user_ns(user_ns); |
b515498f | 50 | |
ae5e1b22 | 51 | return ns; |
ae5e1b22 PE |
52 | } |
53 | ||
b0e77598 | 54 | struct ipc_namespace *copy_ipcs(unsigned long flags, |
bcf58e72 | 55 | struct user_namespace *user_ns, struct ipc_namespace *ns) |
ae5e1b22 | 56 | { |
ae5e1b22 | 57 | if (!(flags & CLONE_NEWIPC)) |
64424289 | 58 | return get_ipc_ns(ns); |
bcf58e72 | 59 | return create_ipc_ns(user_ns, ns); |
ae5e1b22 PE |
60 | } |
61 | ||
01b8b07a PP |
62 | /* |
63 | * free_ipcs - free all ipcs of one type | |
64 | * @ns: the namespace to remove the ipcs from | |
65 | * @ids: the table of ipcs to free | |
66 | * @free: the function called to free each individual ipc | |
67 | * | |
68 | * Called for each kind of ipc when an ipc_namespace exits. | |
69 | */ | |
70 | void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, | |
71 | void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)) | |
72 | { | |
73 | struct kern_ipc_perm *perm; | |
74 | int next_id; | |
75 | int total, in_use; | |
76 | ||
77 | down_write(&ids->rw_mutex); | |
78 | ||
79 | in_use = ids->in_use; | |
80 | ||
81 | for (total = 0, next_id = 0; total < in_use; next_id++) { | |
82 | perm = idr_find(&ids->ipcs_idr, next_id); | |
83 | if (perm == NULL) | |
84 | continue; | |
85 | ipc_lock_by_ptr(perm); | |
86 | free(ns, perm); | |
87 | total++; | |
88 | } | |
89 | up_write(&ids->rw_mutex); | |
90 | } | |
91 | ||
b4188def AD |
92 | static void free_ipc_ns(struct ipc_namespace *ns) |
93 | { | |
94 | /* | |
95 | * Unregistering the hotplug notifier at the beginning guarantees | |
96 | * that the ipc namespace won't be freed while we are inside the | |
97 | * callback routine. Since the blocking_notifier_chain_XXX routines | |
98 | * hold a rw lock on the notifier list, unregister_ipcns_notifier() | |
99 | * won't take the rw lock before blocking_notifier_call_chain() has | |
100 | * released the rd lock. | |
101 | */ | |
102 | unregister_ipcns_notifier(ns); | |
103 | sem_exit_ns(ns); | |
104 | msg_exit_ns(ns); | |
105 | shm_exit_ns(ns); | |
b4188def AD |
106 | atomic_dec(&nr_ipc_ns); |
107 | ||
108 | /* | |
109 | * Do the ipcns removal notification after decrementing nr_ipc_ns in | |
110 | * order to have a correct value when recomputing msgmni. | |
111 | */ | |
112 | ipcns_notify(IPCNS_REMOVED); | |
b515498f | 113 | put_user_ns(ns->user_ns); |
be4d250a | 114 | kfree(ns); |
b4188def AD |
115 | } |
116 | ||
7eafd7c7 SH |
117 | /* |
118 | * put_ipc_ns - drop a reference to an ipc namespace. | |
119 | * @ns: the namespace to put | |
120 | * | |
121 | * If this is the last task in the namespace exiting, and | |
122 | * it is dropping the refcount to 0, then it can race with | |
123 | * a task in another ipc namespace but in a mounts namespace | |
124 | * which has this ipcns's mqueuefs mounted, doing some action | |
125 | * with one of the mqueuefs files. That can raise the refcount. | |
126 | * So dropping the refcount, and raising the refcount when | |
127 | * accessing it through the VFS, are protected with mq_lock. | |
128 | * | |
129 | * (Clearly, a task raising the refcount on its own ipc_ns | |
130 | * needn't take mq_lock since it can't race with the last task | |
131 | * in the ipcns exiting). | |
132 | */ | |
133 | void put_ipc_ns(struct ipc_namespace *ns) | |
ae5e1b22 | 134 | { |
7eafd7c7 SH |
135 | if (atomic_dec_and_lock(&ns->count, &mq_lock)) { |
136 | mq_clear_sbinfo(ns); | |
137 | spin_unlock(&mq_lock); | |
138 | mq_put_mnt(ns); | |
139 | free_ipc_ns(ns); | |
140 | } | |
141 | } | |
a00eaf11 EB |
142 | |
143 | static void *ipcns_get(struct task_struct *task) | |
144 | { | |
145 | struct ipc_namespace *ns = NULL; | |
146 | struct nsproxy *nsproxy; | |
147 | ||
148 | rcu_read_lock(); | |
149 | nsproxy = task_nsproxy(task); | |
150 | if (nsproxy) | |
151 | ns = get_ipc_ns(nsproxy->ipc_ns); | |
152 | rcu_read_unlock(); | |
153 | ||
154 | return ns; | |
155 | } | |
156 | ||
157 | static void ipcns_put(void *ns) | |
158 | { | |
159 | return put_ipc_ns(ns); | |
160 | } | |
161 | ||
142e1d1d | 162 | static int ipcns_install(struct nsproxy *nsproxy, void *new) |
a00eaf11 | 163 | { |
142e1d1d EB |
164 | struct ipc_namespace *ns = new; |
165 | if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) | |
166 | return -EPERM; | |
167 | ||
a00eaf11 EB |
168 | /* Ditch state from the old ipc namespace */ |
169 | exit_sem(current); | |
170 | put_ipc_ns(nsproxy->ipc_ns); | |
171 | nsproxy->ipc_ns = get_ipc_ns(ns); | |
172 | return 0; | |
173 | } | |
174 | ||
175 | const struct proc_ns_operations ipcns_operations = { | |
176 | .name = "ipc", | |
177 | .type = CLONE_NEWIPC, | |
178 | .get = ipcns_get, | |
179 | .put = ipcns_put, | |
180 | .install = ipcns_install, | |
181 | }; |