1 // SPDX-License-Identifier: GPL-2.0
3 * linux/ipc/namespace.c
4 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
9 #include <linux/ipc_namespace.h>
10 #include <linux/rcupdate.h>
11 #include <linux/nsproxy.h>
12 #include <linux/slab.h>
13 #include <linux/cred.h>
15 #include <linux/mount.h>
16 #include <linux/user_namespace.h>
17 #include <linux/proc_ns.h>
18 #include <linux/sched/task.h>
22 static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
24 return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
27 static void dec_ipc_namespaces(struct ucounts *ucounts)
29 dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
32 static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
33 struct ipc_namespace *old_ns)
35 struct ipc_namespace *ns;
36 struct ucounts *ucounts;
40 ucounts = inc_ipc_namespaces(user_ns);
45 ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL_ACCOUNT);
49 err = ns_alloc_inum(&ns->ns);
52 ns->ns.ops = &ipcns_operations;
54 refcount_set(&ns->ns.count, 1);
55 ns->user_ns = get_user_ns(user_ns);
56 ns->ucounts = ucounts;
63 if (!setup_mq_sysctls(ns))
73 put_user_ns(ns->user_ns);
74 ns_free_inum(&ns->ns);
78 dec_ipc_namespaces(ucounts);
83 struct ipc_namespace *copy_ipcs(unsigned long flags,
84 struct user_namespace *user_ns, struct ipc_namespace *ns)
86 if (!(flags & CLONE_NEWIPC))
87 return get_ipc_ns(ns);
88 return create_ipc_ns(user_ns, ns);
92 * free_ipcs - free all ipcs of one type
93 * @ns: the namespace to remove the ipcs from
94 * @ids: the table of ipcs to free
95 * @free: the function called to free each individual ipc
97 * Called for each kind of ipc when an ipc_namespace exits.
99 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
100 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
102 struct kern_ipc_perm *perm;
106 down_write(&ids->rwsem);
108 in_use = ids->in_use;
110 for (total = 0, next_id = 0; total < in_use; next_id++) {
111 perm = idr_find(&ids->ipcs_idr, next_id);
115 ipc_lock_object(perm);
119 up_write(&ids->rwsem);
122 static void free_ipc_ns(struct ipc_namespace *ns)
124 /* mq_put_mnt() waits for a grace period as kern_unmount()
125 * uses synchronize_rcu().
132 retire_mq_sysctls(ns);
134 dec_ipc_namespaces(ns->ucounts);
135 put_user_ns(ns->user_ns);
136 ns_free_inum(&ns->ns);
140 static LLIST_HEAD(free_ipc_list);
141 static void free_ipc(struct work_struct *unused)
143 struct llist_node *node = llist_del_all(&free_ipc_list);
144 struct ipc_namespace *n, *t;
146 llist_for_each_entry_safe(n, t, node, mnt_llist)
151 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
153 static DECLARE_WORK(free_ipc_work, free_ipc);
156 * put_ipc_ns - drop a reference to an ipc namespace.
157 * @ns: the namespace to put
159 * If this is the last task in the namespace exiting, and
160 * it is dropping the refcount to 0, then it can race with
161 * a task in another ipc namespace but in a mounts namespace
162 * which has this ipcns's mqueuefs mounted, doing some action
163 * with one of the mqueuefs files. That can raise the refcount.
164 * So dropping the refcount, and raising the refcount when
165 * accessing it through the VFS, are protected with mq_lock.
167 * (Clearly, a task raising the refcount on its own ipc_ns
168 * needn't take mq_lock since it can't race with the last task
169 * in the ipcns exiting).
171 void put_ipc_ns(struct ipc_namespace *ns)
173 if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
175 spin_unlock(&mq_lock);
177 if (llist_add(&ns->mnt_llist, &free_ipc_list))
178 schedule_work(&free_ipc_work);
182 static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
184 return container_of(ns, struct ipc_namespace, ns);
187 static struct ns_common *ipcns_get(struct task_struct *task)
189 struct ipc_namespace *ns = NULL;
190 struct nsproxy *nsproxy;
193 nsproxy = task->nsproxy;
195 ns = get_ipc_ns(nsproxy->ipc_ns);
198 return ns ? &ns->ns : NULL;
201 static void ipcns_put(struct ns_common *ns)
203 return put_ipc_ns(to_ipc_ns(ns));
206 static int ipcns_install(struct nsset *nsset, struct ns_common *new)
208 struct nsproxy *nsproxy = nsset->nsproxy;
209 struct ipc_namespace *ns = to_ipc_ns(new);
210 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
211 !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
214 put_ipc_ns(nsproxy->ipc_ns);
215 nsproxy->ipc_ns = get_ipc_ns(ns);
219 static struct user_namespace *ipcns_owner(struct ns_common *ns)
221 return to_ipc_ns(ns)->user_ns;
224 const struct proc_ns_operations ipcns_operations = {
226 .type = CLONE_NEWIPC,
229 .install = ipcns_install,
230 .owner = ipcns_owner,