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
= proc_alloc_inum(&ns
->proc_inum
);
35 atomic_set(&ns
->count
, 1);
38 proc_free_inum(ns
->proc_inum
);
42 atomic_inc(&nr_ipc_ns
);
48 ns
->user_ns
= get_user_ns(user_ns
);
53 struct ipc_namespace
*copy_ipcs(unsigned long flags
,
54 struct user_namespace
*user_ns
, struct ipc_namespace
*ns
)
56 if (!(flags
& CLONE_NEWIPC
))
57 return get_ipc_ns(ns
);
58 return create_ipc_ns(user_ns
, ns
);
62 * free_ipcs - free all ipcs of one type
63 * @ns: the namespace to remove the ipcs from
64 * @ids: the table of ipcs to free
65 * @free: the function called to free each individual ipc
67 * Called for each kind of ipc when an ipc_namespace exits.
69 void free_ipcs(struct ipc_namespace
*ns
, struct ipc_ids
*ids
,
70 void (*free
)(struct ipc_namespace
*, struct kern_ipc_perm
*))
72 struct kern_ipc_perm
*perm
;
76 down_write(&ids
->rwsem
);
80 for (total
= 0, next_id
= 0; total
< in_use
; next_id
++) {
81 perm
= idr_find(&ids
->ipcs_idr
, next_id
);
85 ipc_lock_object(perm
);
89 up_write(&ids
->rwsem
);
92 static void free_ipc_ns(struct ipc_namespace
*ns
)
97 atomic_dec(&nr_ipc_ns
);
99 put_user_ns(ns
->user_ns
);
100 proc_free_inum(ns
->proc_inum
);
105 * put_ipc_ns - drop a reference to an ipc namespace.
106 * @ns: the namespace to put
108 * If this is the last task in the namespace exiting, and
109 * it is dropping the refcount to 0, then it can race with
110 * a task in another ipc namespace but in a mounts namespace
111 * which has this ipcns's mqueuefs mounted, doing some action
112 * with one of the mqueuefs files. That can raise the refcount.
113 * So dropping the refcount, and raising the refcount when
114 * accessing it through the VFS, are protected with mq_lock.
116 * (Clearly, a task raising the refcount on its own ipc_ns
117 * needn't take mq_lock since it can't race with the last task
118 * in the ipcns exiting).
120 void put_ipc_ns(struct ipc_namespace
*ns
)
122 if (atomic_dec_and_lock(&ns
->count
, &mq_lock
)) {
124 spin_unlock(&mq_lock
);
130 static void *ipcns_get(struct task_struct
*task
)
132 struct ipc_namespace
*ns
= NULL
;
133 struct nsproxy
*nsproxy
;
136 nsproxy
= task
->nsproxy
;
138 ns
= get_ipc_ns(nsproxy
->ipc_ns
);
144 static void ipcns_put(void *ns
)
146 return put_ipc_ns(ns
);
149 static int ipcns_install(struct nsproxy
*nsproxy
, void *new)
151 struct ipc_namespace
*ns
= new;
152 if (!ns_capable(ns
->user_ns
, CAP_SYS_ADMIN
) ||
153 !ns_capable(current_user_ns(), CAP_SYS_ADMIN
))
156 /* Ditch state from the old ipc namespace */
158 put_ipc_ns(nsproxy
->ipc_ns
);
159 nsproxy
->ipc_ns
= get_ipc_ns(ns
);
163 static unsigned int ipcns_inum(void *vp
)
165 struct ipc_namespace
*ns
= vp
;
167 return ns
->proc_inum
;
170 const struct proc_ns_operations ipcns_operations
= {
172 .type
= CLONE_NEWIPC
,
175 .install
= ipcns_install
,