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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};
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
22static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
23{
24 return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
25}
26
27static void dec_ipc_namespaces(struct ucounts *ucounts)
28{
29 dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
30}
31
32static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
33 struct ipc_namespace *old_ns)
34{
35 struct ipc_namespace *ns;
36 struct ucounts *ucounts;
37 int err;
38
39 err = -ENOSPC;
40 ucounts = inc_ipc_namespaces(user_ns);
41 if (!ucounts)
42 goto fail;
43
44 err = -ENOMEM;
45 ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
46 if (ns == NULL)
47 goto fail_dec;
48
49 err = ns_alloc_inum(&ns->ns);
50 if (err)
51 goto fail_free;
52 ns->ns.ops = &ipcns_operations;
53
54 refcount_set(&ns->count, 1);
55 ns->user_ns = get_user_ns(user_ns);
56 ns->ucounts = ucounts;
57
58 err = mq_init_ns(ns);
59 if (err)
60 goto fail_put;
61
62 sem_init_ns(ns);
63 msg_init_ns(ns);
64 shm_init_ns(ns);
65
66 return ns;
67
68fail_put:
69 put_user_ns(ns->user_ns);
70 ns_free_inum(&ns->ns);
71fail_free:
72 kfree(ns);
73fail_dec:
74 dec_ipc_namespaces(ucounts);
75fail:
76 return ERR_PTR(err);
77}
78
79struct ipc_namespace *copy_ipcs(unsigned long flags,
80 struct user_namespace *user_ns, struct ipc_namespace *ns)
81{
82 if (!(flags & CLONE_NEWIPC))
83 return get_ipc_ns(ns);
84 return create_ipc_ns(user_ns, ns);
85}
86
87/*
88 * free_ipcs - free all ipcs of one type
89 * @ns: the namespace to remove the ipcs from
90 * @ids: the table of ipcs to free
91 * @free: the function called to free each individual ipc
92 *
93 * Called for each kind of ipc when an ipc_namespace exits.
94 */
95void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
96 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
97{
98 struct kern_ipc_perm *perm;
99 int next_id;
100 int total, in_use;
101
102 down_write(&ids->rwsem);
103
104 in_use = ids->in_use;
105
106 for (total = 0, next_id = 0; total < in_use; next_id++) {
107 perm = idr_find(&ids->ipcs_idr, next_id);
108 if (perm == NULL)
109 continue;
110 rcu_read_lock();
111 ipc_lock_object(perm);
112 free(ns, perm);
113 total++;
114 }
115 up_write(&ids->rwsem);
116}
117
118static void free_ipc_ns(struct ipc_namespace *ns)
119{
120 sem_exit_ns(ns);
121 msg_exit_ns(ns);
122 shm_exit_ns(ns);
123
124 dec_ipc_namespaces(ns->ucounts);
125 put_user_ns(ns->user_ns);
126 ns_free_inum(&ns->ns);
127 kfree(ns);
128}
129
130/*
131 * put_ipc_ns - drop a reference to an ipc namespace.
132 * @ns: the namespace to put
133 *
134 * If this is the last task in the namespace exiting, and
135 * it is dropping the refcount to 0, then it can race with
136 * a task in another ipc namespace but in a mounts namespace
137 * which has this ipcns's mqueuefs mounted, doing some action
138 * with one of the mqueuefs files. That can raise the refcount.
139 * So dropping the refcount, and raising the refcount when
140 * accessing it through the VFS, are protected with mq_lock.
141 *
142 * (Clearly, a task raising the refcount on its own ipc_ns
143 * needn't take mq_lock since it can't race with the last task
144 * in the ipcns exiting).
145 */
146void put_ipc_ns(struct ipc_namespace *ns)
147{
148 if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
149 mq_clear_sbinfo(ns);
150 spin_unlock(&mq_lock);
151 mq_put_mnt(ns);
152 free_ipc_ns(ns);
153 }
154}
155
156static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
157{
158 return container_of(ns, struct ipc_namespace, ns);
159}
160
161static struct ns_common *ipcns_get(struct task_struct *task)
162{
163 struct ipc_namespace *ns = NULL;
164 struct nsproxy *nsproxy;
165
166 task_lock(task);
167 nsproxy = task->nsproxy;
168 if (nsproxy)
169 ns = get_ipc_ns(nsproxy->ipc_ns);
170 task_unlock(task);
171
172 return ns ? &ns->ns : NULL;
173}
174
175static void ipcns_put(struct ns_common *ns)
176{
177 return put_ipc_ns(to_ipc_ns(ns));
178}
179
180static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
181{
182 struct ipc_namespace *ns = to_ipc_ns(new);
183 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
184 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
185 return -EPERM;
186
187 /* Ditch state from the old ipc namespace */
188 exit_sem(current);
189 put_ipc_ns(nsproxy->ipc_ns);
190 nsproxy->ipc_ns = get_ipc_ns(ns);
191 return 0;
192}
193
194static struct user_namespace *ipcns_owner(struct ns_common *ns)
195{
196 return to_ipc_ns(ns)->user_ns;
197}
198
199const struct proc_ns_operations ipcns_operations = {
200 .name = "ipc",
201 .type = CLONE_NEWIPC,
202 .get = ipcns_get,
203 .put = ipcns_put,
204 .install = ipcns_install,
205 .owner = ipcns_owner,
206};