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>
12 #include <linux/cred.h>
14 #include <linux/mount.h>
15 #include <linux/user_namespace.h>
16 #include <linux/proc_ns.h>
20 static struct ucounts
*inc_ipc_namespaces(struct user_namespace
*ns
)
22 return inc_ucount(ns
, current_euid(), UCOUNT_IPC_NAMESPACES
);
25 static void dec_ipc_namespaces(struct ucounts
*ucounts
)
27 dec_ucount(ucounts
, UCOUNT_IPC_NAMESPACES
);
30 static struct ipc_namespace
*create_ipc_ns(struct user_namespace
*user_ns
,
31 struct ipc_namespace
*old_ns
)
33 struct ipc_namespace
*ns
;
34 struct ucounts
*ucounts
;
38 ucounts
= inc_ipc_namespaces(user_ns
);
43 ns
= kmalloc(sizeof(struct ipc_namespace
), GFP_KERNEL
);
47 err
= ns_alloc_inum(&ns
->ns
);
50 ns
->ns
.ops
= &ipcns_operations
;
52 atomic_set(&ns
->count
, 1);
53 ns
->user_ns
= get_user_ns(user_ns
);
54 ns
->ucounts
= ucounts
;
67 put_user_ns(ns
->user_ns
);
68 ns_free_inum(&ns
->ns
);
72 dec_ipc_namespaces(ucounts
);
77 struct ipc_namespace
*copy_ipcs(unsigned long flags
,
78 struct user_namespace
*user_ns
, struct ipc_namespace
*ns
)
80 if (!(flags
& CLONE_NEWIPC
))
81 return get_ipc_ns(ns
);
82 return create_ipc_ns(user_ns
, ns
);
86 * free_ipcs - free all ipcs of one type
87 * @ns: the namespace to remove the ipcs from
88 * @ids: the table of ipcs to free
89 * @free: the function called to free each individual ipc
91 * Called for each kind of ipc when an ipc_namespace exits.
93 void free_ipcs(struct ipc_namespace
*ns
, struct ipc_ids
*ids
,
94 void (*free
)(struct ipc_namespace
*, struct kern_ipc_perm
*))
96 struct kern_ipc_perm
*perm
;
100 down_write(&ids
->rwsem
);
102 in_use
= ids
->in_use
;
104 for (total
= 0, next_id
= 0; total
< in_use
; next_id
++) {
105 perm
= idr_find(&ids
->ipcs_idr
, next_id
);
109 ipc_lock_object(perm
);
113 up_write(&ids
->rwsem
);
116 static void free_ipc_ns(struct ipc_namespace
*ns
)
122 dec_ipc_namespaces(ns
->ucounts
);
123 put_user_ns(ns
->user_ns
);
124 ns_free_inum(&ns
->ns
);
129 * put_ipc_ns - drop a reference to an ipc namespace.
130 * @ns: the namespace to put
132 * If this is the last task in the namespace exiting, and
133 * it is dropping the refcount to 0, then it can race with
134 * a task in another ipc namespace but in a mounts namespace
135 * which has this ipcns's mqueuefs mounted, doing some action
136 * with one of the mqueuefs files. That can raise the refcount.
137 * So dropping the refcount, and raising the refcount when
138 * accessing it through the VFS, are protected with mq_lock.
140 * (Clearly, a task raising the refcount on its own ipc_ns
141 * needn't take mq_lock since it can't race with the last task
142 * in the ipcns exiting).
144 void put_ipc_ns(struct ipc_namespace
*ns
)
146 if (atomic_dec_and_lock(&ns
->count
, &mq_lock
)) {
148 spin_unlock(&mq_lock
);
154 static inline struct ipc_namespace
*to_ipc_ns(struct ns_common
*ns
)
156 return container_of(ns
, struct ipc_namespace
, ns
);
159 static struct ns_common
*ipcns_get(struct task_struct
*task
)
161 struct ipc_namespace
*ns
= NULL
;
162 struct nsproxy
*nsproxy
;
165 nsproxy
= task
->nsproxy
;
167 ns
= get_ipc_ns(nsproxy
->ipc_ns
);
170 return ns
? &ns
->ns
: NULL
;
173 static void ipcns_put(struct ns_common
*ns
)
175 return put_ipc_ns(to_ipc_ns(ns
));
178 static int ipcns_install(struct nsproxy
*nsproxy
, struct ns_common
*new)
180 struct ipc_namespace
*ns
= to_ipc_ns(new);
181 if (!ns_capable(ns
->user_ns
, CAP_SYS_ADMIN
) ||
182 !ns_capable(current_user_ns(), CAP_SYS_ADMIN
))
185 /* Ditch state from the old ipc namespace */
187 put_ipc_ns(nsproxy
->ipc_ns
);
188 nsproxy
->ipc_ns
= get_ipc_ns(ns
);
192 static struct user_namespace
*ipcns_owner(struct ns_common
*ns
)
194 return to_ipc_ns(ns
)->user_ns
;
197 const struct proc_ns_operations ipcns_operations
= {
199 .type
= CLONE_NEWIPC
,
202 .install
= ipcns_install
,
203 .owner
= ipcns_owner
,