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,