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,