2 * linux/ipc/namespace.c
3 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
8 #include <linux/ipc_namespace.h>
9 #include <linux/rcupdate.h>
10 #include <linux/nsproxy.h>
11 #include <linux/slab.h>
13 #include <linux/mount.h>
14 #include <linux/user_namespace.h>
15 #include <linux/proc_ns.h>
19 static struct ipc_namespace
*create_ipc_ns(struct user_namespace
*user_ns
,
20 struct ipc_namespace
*old_ns
)
22 struct ipc_namespace
*ns
;
25 ns
= kmalloc(sizeof(struct ipc_namespace
), GFP_KERNEL
);
27 return ERR_PTR(-ENOMEM
);
29 err
= ns_alloc_inum(&ns
->ns
);
34 ns
->ns
.ops
= &ipcns_operations
;
36 atomic_set(&ns
->count
, 1);
39 ns_free_inum(&ns
->ns
);
43 atomic_inc(&nr_ipc_ns
);
49 ns
->user_ns
= get_user_ns(user_ns
);
54 struct ipc_namespace
*copy_ipcs(unsigned long flags
,
55 struct user_namespace
*user_ns
, struct ipc_namespace
*ns
)
57 if (!(flags
& CLONE_NEWIPC
))
58 return get_ipc_ns(ns
);
59 return create_ipc_ns(user_ns
, ns
);
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
68 * Called for each kind of ipc when an ipc_namespace exits.
70 void free_ipcs(struct ipc_namespace
*ns
, struct ipc_ids
*ids
,
71 void (*free
)(struct ipc_namespace
*, struct kern_ipc_perm
*))
73 struct kern_ipc_perm
*perm
;
77 down_write(&ids
->rwsem
);
81 for (total
= 0, next_id
= 0; total
< in_use
; next_id
++) {
82 perm
= idr_find(&ids
->ipcs_idr
, next_id
);
86 ipc_lock_object(perm
);
90 up_write(&ids
->rwsem
);
93 static void free_ipc_ns(struct ipc_namespace
*ns
)
98 atomic_dec(&nr_ipc_ns
);
100 put_user_ns(ns
->user_ns
);
101 ns_free_inum(&ns
->ns
);
106 * put_ipc_ns - drop a reference to an ipc namespace.
107 * @ns: the namespace to put
109 * If this is the last task in the namespace exiting, and
110 * it is dropping the refcount to 0, then it can race with
111 * a task in another ipc namespace but in a mounts namespace
112 * which has this ipcns's mqueuefs mounted, doing some action
113 * with one of the mqueuefs files. That can raise the refcount.
114 * So dropping the refcount, and raising the refcount when
115 * accessing it through the VFS, are protected with mq_lock.
117 * (Clearly, a task raising the refcount on its own ipc_ns
118 * needn't take mq_lock since it can't race with the last task
119 * in the ipcns exiting).
121 void put_ipc_ns(struct ipc_namespace
*ns
)
123 if (atomic_dec_and_lock(&ns
->count
, &mq_lock
)) {
125 spin_unlock(&mq_lock
);
131 static inline struct ipc_namespace
*to_ipc_ns(struct ns_common
*ns
)
133 return container_of(ns
, struct ipc_namespace
, ns
);
136 static struct ns_common
*ipcns_get(struct task_struct
*task
)
138 struct ipc_namespace
*ns
= NULL
;
139 struct nsproxy
*nsproxy
;
142 nsproxy
= task
->nsproxy
;
144 ns
= get_ipc_ns(nsproxy
->ipc_ns
);
147 return ns
? &ns
->ns
: NULL
;
150 static void ipcns_put(struct ns_common
*ns
)
152 return put_ipc_ns(to_ipc_ns(ns
));
155 static int ipcns_install(struct nsproxy
*nsproxy
, struct ns_common
*new)
157 struct ipc_namespace
*ns
= to_ipc_ns(new);
158 if (!ns_capable(ns
->user_ns
, CAP_SYS_ADMIN
) ||
159 !ns_capable(current_user_ns(), CAP_SYS_ADMIN
))
162 /* Ditch state from the old ipc namespace */
164 put_ipc_ns(nsproxy
->ipc_ns
);
165 nsproxy
->ipc_ns
= get_ipc_ns(ns
);
169 const struct proc_ns_operations ipcns_operations
= {
171 .type
= CLONE_NEWIPC
,
174 .install
= ipcns_install
,