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1/*
2 * linux/ipc/namespace.c
3 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
4 */
5
6#include <linux/ipc.h>
7#include <linux/msg.h>
8#include <linux/ipc_namespace.h>
9#include <linux/rcupdate.h>
10#include <linux/nsproxy.h>
11#include <linux/slab.h>
12#include <linux/fs.h>
13#include <linux/mount.h>
14#include <linux/user_namespace.h>
15#include <linux/proc_fs.h>
16
17#include "util.h"
18
19static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
20 struct ipc_namespace *old_ns)
21{
22 struct ipc_namespace *ns;
23 int err;
24
25 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
26 if (ns == NULL)
27 return ERR_PTR(-ENOMEM);
28
29 atomic_set(&ns->count, 1);
30 err = mq_init_ns(ns);
31 if (err) {
32 kfree(ns);
33 return ERR_PTR(err);
34 }
35 atomic_inc(&nr_ipc_ns);
36
37 sem_init_ns(ns);
38 msg_init_ns(ns);
39 shm_init_ns(ns);
40
41 /*
42 * msgmni has already been computed for the new ipc ns.
43 * Thus, do the ipcns creation notification before registering that
44 * new ipcns in the chain.
45 */
46 ipcns_notify(IPCNS_CREATED);
47 register_ipcns_notifier(ns);
48
49 ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
50
51 return ns;
52}
53
54struct ipc_namespace *copy_ipcs(unsigned long flags,
55 struct task_struct *tsk)
56{
57 struct ipc_namespace *ns = tsk->nsproxy->ipc_ns;
58
59 if (!(flags & CLONE_NEWIPC))
60 return get_ipc_ns(ns);
61 return create_ipc_ns(tsk, ns);
62}
63
64/*
65 * free_ipcs - free all ipcs of one type
66 * @ns: the namespace to remove the ipcs from
67 * @ids: the table of ipcs to free
68 * @free: the function called to free each individual ipc
69 *
70 * Called for each kind of ipc when an ipc_namespace exits.
71 */
72void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
73 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
74{
75 struct kern_ipc_perm *perm;
76 int next_id;
77 int total, in_use;
78
79 down_write(&ids->rw_mutex);
80
81 in_use = ids->in_use;
82
83 for (total = 0, next_id = 0; total < in_use; next_id++) {
84 perm = idr_find(&ids->ipcs_idr, next_id);
85 if (perm == NULL)
86 continue;
87 ipc_lock_by_ptr(perm);
88 free(ns, perm);
89 total++;
90 }
91 up_write(&ids->rw_mutex);
92}
93
94static void free_ipc_ns(struct ipc_namespace *ns)
95{
96 /*
97 * Unregistering the hotplug notifier at the beginning guarantees
98 * that the ipc namespace won't be freed while we are inside the
99 * callback routine. Since the blocking_notifier_chain_XXX routines
100 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
101 * won't take the rw lock before blocking_notifier_call_chain() has
102 * released the rd lock.
103 */
104 unregister_ipcns_notifier(ns);
105 sem_exit_ns(ns);
106 msg_exit_ns(ns);
107 shm_exit_ns(ns);
108 atomic_dec(&nr_ipc_ns);
109
110 /*
111 * Do the ipcns removal notification after decrementing nr_ipc_ns in
112 * order to have a correct value when recomputing msgmni.
113 */
114 ipcns_notify(IPCNS_REMOVED);
115 put_user_ns(ns->user_ns);
116 kfree(ns);
117}
118
119/*
120 * put_ipc_ns - drop a reference to an ipc namespace.
121 * @ns: the namespace to put
122 *
123 * If this is the last task in the namespace exiting, and
124 * it is dropping the refcount to 0, then it can race with
125 * a task in another ipc namespace but in a mounts namespace
126 * which has this ipcns's mqueuefs mounted, doing some action
127 * with one of the mqueuefs files. That can raise the refcount.
128 * So dropping the refcount, and raising the refcount when
129 * accessing it through the VFS, are protected with mq_lock.
130 *
131 * (Clearly, a task raising the refcount on its own ipc_ns
132 * needn't take mq_lock since it can't race with the last task
133 * in the ipcns exiting).
134 */
135void put_ipc_ns(struct ipc_namespace *ns)
136{
137 if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
138 mq_clear_sbinfo(ns);
139 spin_unlock(&mq_lock);
140 mq_put_mnt(ns);
141 free_ipc_ns(ns);
142 }
143}
144
145static void *ipcns_get(struct task_struct *task)
146{
147 struct ipc_namespace *ns = NULL;
148 struct nsproxy *nsproxy;
149
150 rcu_read_lock();
151 nsproxy = task_nsproxy(task);
152 if (nsproxy)
153 ns = get_ipc_ns(nsproxy->ipc_ns);
154 rcu_read_unlock();
155
156 return ns;
157}
158
159static void ipcns_put(void *ns)
160{
161 return put_ipc_ns(ns);
162}
163
164static int ipcns_install(struct nsproxy *nsproxy, void *ns)
165{
166 /* Ditch state from the old ipc namespace */
167 exit_sem(current);
168 put_ipc_ns(nsproxy->ipc_ns);
169 nsproxy->ipc_ns = get_ipc_ns(ns);
170 return 0;
171}
172
173const struct proc_ns_operations ipcns_operations = {
174 .name = "ipc",
175 .type = CLONE_NEWIPC,
176 .get = ipcns_get,
177 .put = ipcns_put,
178 .install = ipcns_install,
179};
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/namespace.c
4 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
5 */
6
7#include <linux/ipc.h>
8#include <linux/msg.h>
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>
14#include <linux/fs.h>
15#include <linux/mount.h>
16#include <linux/user_namespace.h>
17#include <linux/proc_ns.h>
18#include <linux/sched/task.h>
19
20#include "util.h"
21
22/*
23 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
24 */
25static void free_ipc(struct work_struct *unused);
26static DECLARE_WORK(free_ipc_work, free_ipc);
27
28static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
29{
30 return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
31}
32
33static void dec_ipc_namespaces(struct ucounts *ucounts)
34{
35 dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
36}
37
38static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
39 struct ipc_namespace *old_ns)
40{
41 struct ipc_namespace *ns;
42 struct ucounts *ucounts;
43 int err;
44
45 err = -ENOSPC;
46 again:
47 ucounts = inc_ipc_namespaces(user_ns);
48 if (!ucounts) {
49 /*
50 * IPC namespaces are freed asynchronously, by free_ipc_work.
51 * If frees were pending, flush_work will wait, and
52 * return true. Fail the allocation if no frees are pending.
53 */
54 if (flush_work(&free_ipc_work))
55 goto again;
56 goto fail;
57 }
58
59 err = -ENOMEM;
60 ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL_ACCOUNT);
61 if (ns == NULL)
62 goto fail_dec;
63
64 err = ns_alloc_inum(&ns->ns);
65 if (err)
66 goto fail_free;
67 ns->ns.ops = &ipcns_operations;
68
69 refcount_set(&ns->ns.count, 1);
70 ns->user_ns = get_user_ns(user_ns);
71 ns->ucounts = ucounts;
72
73 err = mq_init_ns(ns);
74 if (err)
75 goto fail_put;
76
77 err = -ENOMEM;
78 if (!setup_mq_sysctls(ns))
79 goto fail_put;
80
81 if (!setup_ipc_sysctls(ns))
82 goto fail_mq;
83
84 err = msg_init_ns(ns);
85 if (err)
86 goto fail_put;
87
88 sem_init_ns(ns);
89 shm_init_ns(ns);
90
91 return ns;
92
93fail_mq:
94 retire_mq_sysctls(ns);
95
96fail_put:
97 put_user_ns(ns->user_ns);
98 ns_free_inum(&ns->ns);
99fail_free:
100 kfree(ns);
101fail_dec:
102 dec_ipc_namespaces(ucounts);
103fail:
104 return ERR_PTR(err);
105}
106
107struct ipc_namespace *copy_ipcs(unsigned long flags,
108 struct user_namespace *user_ns, struct ipc_namespace *ns)
109{
110 if (!(flags & CLONE_NEWIPC))
111 return get_ipc_ns(ns);
112 return create_ipc_ns(user_ns, ns);
113}
114
115/*
116 * free_ipcs - free all ipcs of one type
117 * @ns: the namespace to remove the ipcs from
118 * @ids: the table of ipcs to free
119 * @free: the function called to free each individual ipc
120 *
121 * Called for each kind of ipc when an ipc_namespace exits.
122 */
123void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
124 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
125{
126 struct kern_ipc_perm *perm;
127 int next_id;
128 int total, in_use;
129
130 down_write(&ids->rwsem);
131
132 in_use = ids->in_use;
133
134 for (total = 0, next_id = 0; total < in_use; next_id++) {
135 perm = idr_find(&ids->ipcs_idr, next_id);
136 if (perm == NULL)
137 continue;
138 rcu_read_lock();
139 ipc_lock_object(perm);
140 free(ns, perm);
141 total++;
142 }
143 up_write(&ids->rwsem);
144}
145
146static void free_ipc_ns(struct ipc_namespace *ns)
147{
148 /*
149 * Caller needs to wait for an RCU grace period to have passed
150 * after making the mount point inaccessible to new accesses.
151 */
152 mntput(ns->mq_mnt);
153 sem_exit_ns(ns);
154 msg_exit_ns(ns);
155 shm_exit_ns(ns);
156
157 retire_mq_sysctls(ns);
158 retire_ipc_sysctls(ns);
159
160 dec_ipc_namespaces(ns->ucounts);
161 put_user_ns(ns->user_ns);
162 ns_free_inum(&ns->ns);
163 kfree(ns);
164}
165
166static LLIST_HEAD(free_ipc_list);
167static void free_ipc(struct work_struct *unused)
168{
169 struct llist_node *node = llist_del_all(&free_ipc_list);
170 struct ipc_namespace *n, *t;
171
172 llist_for_each_entry_safe(n, t, node, mnt_llist)
173 mnt_make_shortterm(n->mq_mnt);
174
175 /* Wait for any last users to have gone away. */
176 synchronize_rcu();
177
178 llist_for_each_entry_safe(n, t, node, mnt_llist)
179 free_ipc_ns(n);
180}
181
182/*
183 * put_ipc_ns - drop a reference to an ipc namespace.
184 * @ns: the namespace to put
185 *
186 * If this is the last task in the namespace exiting, and
187 * it is dropping the refcount to 0, then it can race with
188 * a task in another ipc namespace but in a mounts namespace
189 * which has this ipcns's mqueuefs mounted, doing some action
190 * with one of the mqueuefs files. That can raise the refcount.
191 * So dropping the refcount, and raising the refcount when
192 * accessing it through the VFS, are protected with mq_lock.
193 *
194 * (Clearly, a task raising the refcount on its own ipc_ns
195 * needn't take mq_lock since it can't race with the last task
196 * in the ipcns exiting).
197 */
198void put_ipc_ns(struct ipc_namespace *ns)
199{
200 if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
201 mq_clear_sbinfo(ns);
202 spin_unlock(&mq_lock);
203
204 if (llist_add(&ns->mnt_llist, &free_ipc_list))
205 schedule_work(&free_ipc_work);
206 }
207}
208
209static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
210{
211 return container_of(ns, struct ipc_namespace, ns);
212}
213
214static struct ns_common *ipcns_get(struct task_struct *task)
215{
216 struct ipc_namespace *ns = NULL;
217 struct nsproxy *nsproxy;
218
219 task_lock(task);
220 nsproxy = task->nsproxy;
221 if (nsproxy)
222 ns = get_ipc_ns(nsproxy->ipc_ns);
223 task_unlock(task);
224
225 return ns ? &ns->ns : NULL;
226}
227
228static void ipcns_put(struct ns_common *ns)
229{
230 return put_ipc_ns(to_ipc_ns(ns));
231}
232
233static int ipcns_install(struct nsset *nsset, struct ns_common *new)
234{
235 struct nsproxy *nsproxy = nsset->nsproxy;
236 struct ipc_namespace *ns = to_ipc_ns(new);
237 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
238 !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
239 return -EPERM;
240
241 put_ipc_ns(nsproxy->ipc_ns);
242 nsproxy->ipc_ns = get_ipc_ns(ns);
243 return 0;
244}
245
246static struct user_namespace *ipcns_owner(struct ns_common *ns)
247{
248 return to_ipc_ns(ns)->user_ns;
249}
250
251const struct proc_ns_operations ipcns_operations = {
252 .name = "ipc",
253 .type = CLONE_NEWIPC,
254 .get = ipcns_get,
255 .put = ipcns_put,
256 .install = ipcns_install,
257 .owner = ipcns_owner,
258};