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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_ns.h>
16
17#include "util.h"
18
19static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
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 err = ns_alloc_inum(&ns->ns);
30 if (err) {
31 kfree(ns);
32 return ERR_PTR(err);
33 }
34 ns->ns.ops = &ipcns_operations;
35
36 atomic_set(&ns->count, 1);
37 err = mq_init_ns(ns);
38 if (err) {
39 ns_free_inum(&ns->ns);
40 kfree(ns);
41 return ERR_PTR(err);
42 }
43 atomic_inc(&nr_ipc_ns);
44
45 sem_init_ns(ns);
46 msg_init_ns(ns);
47 shm_init_ns(ns);
48
49 ns->user_ns = get_user_ns(user_ns);
50
51 return ns;
52}
53
54struct ipc_namespace *copy_ipcs(unsigned long flags,
55 struct user_namespace *user_ns, struct ipc_namespace *ns)
56{
57 if (!(flags & CLONE_NEWIPC))
58 return get_ipc_ns(ns);
59 return create_ipc_ns(user_ns, ns);
60}
61
62/*
63 * free_ipcs - free all ipcs of one type
64 * @ns: the namespace to remove the ipcs from
65 * @ids: the table of ipcs to free
66 * @free: the function called to free each individual ipc
67 *
68 * Called for each kind of ipc when an ipc_namespace exits.
69 */
70void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
71 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
72{
73 struct kern_ipc_perm *perm;
74 int next_id;
75 int total, in_use;
76
77 down_write(&ids->rwsem);
78
79 in_use = ids->in_use;
80
81 for (total = 0, next_id = 0; total < in_use; next_id++) {
82 perm = idr_find(&ids->ipcs_idr, next_id);
83 if (perm == NULL)
84 continue;
85 rcu_read_lock();
86 ipc_lock_object(perm);
87 free(ns, perm);
88 total++;
89 }
90 up_write(&ids->rwsem);
91}
92
93static void free_ipc_ns(struct ipc_namespace *ns)
94{
95 sem_exit_ns(ns);
96 msg_exit_ns(ns);
97 shm_exit_ns(ns);
98 atomic_dec(&nr_ipc_ns);
99
100 put_user_ns(ns->user_ns);
101 ns_free_inum(&ns->ns);
102 kfree(ns);
103}
104
105/*
106 * put_ipc_ns - drop a reference to an ipc namespace.
107 * @ns: the namespace to put
108 *
109 * If this is the last task in the namespace exiting, and
110 * it is dropping the refcount to 0, then it can race with
111 * a task in another ipc namespace but in a mounts namespace
112 * which has this ipcns's mqueuefs mounted, doing some action
113 * with one of the mqueuefs files. That can raise the refcount.
114 * So dropping the refcount, and raising the refcount when
115 * accessing it through the VFS, are protected with mq_lock.
116 *
117 * (Clearly, a task raising the refcount on its own ipc_ns
118 * needn't take mq_lock since it can't race with the last task
119 * in the ipcns exiting).
120 */
121void put_ipc_ns(struct ipc_namespace *ns)
122{
123 if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
124 mq_clear_sbinfo(ns);
125 spin_unlock(&mq_lock);
126 mq_put_mnt(ns);
127 free_ipc_ns(ns);
128 }
129}
130
131static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
132{
133 return container_of(ns, struct ipc_namespace, ns);
134}
135
136static struct ns_common *ipcns_get(struct task_struct *task)
137{
138 struct ipc_namespace *ns = NULL;
139 struct nsproxy *nsproxy;
140
141 task_lock(task);
142 nsproxy = task->nsproxy;
143 if (nsproxy)
144 ns = get_ipc_ns(nsproxy->ipc_ns);
145 task_unlock(task);
146
147 return ns ? &ns->ns : NULL;
148}
149
150static void ipcns_put(struct ns_common *ns)
151{
152 return put_ipc_ns(to_ipc_ns(ns));
153}
154
155static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
156{
157 struct ipc_namespace *ns = to_ipc_ns(new);
158 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
159 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
160 return -EPERM;
161
162 /* Ditch state from the old ipc namespace */
163 exit_sem(current);
164 put_ipc_ns(nsproxy->ipc_ns);
165 nsproxy->ipc_ns = get_ipc_ns(ns);
166 return 0;
167}
168
169const struct proc_ns_operations ipcns_operations = {
170 .name = "ipc",
171 .type = CLONE_NEWIPC,
172 .get = ipcns_get,
173 .put = ipcns_put,
174 .install = ipcns_install,
175};
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_ACCOUNT);
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->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 err = -ENOMEM;
63 if (!setup_mq_sysctls(ns))
64 goto fail_put;
65
66 if (!setup_ipc_sysctls(ns))
67 goto fail_mq;
68
69 err = msg_init_ns(ns);
70 if (err)
71 goto fail_put;
72
73 sem_init_ns(ns);
74 shm_init_ns(ns);
75
76 return ns;
77
78fail_mq:
79 retire_mq_sysctls(ns);
80
81fail_put:
82 put_user_ns(ns->user_ns);
83 ns_free_inum(&ns->ns);
84fail_free:
85 kfree(ns);
86fail_dec:
87 dec_ipc_namespaces(ucounts);
88fail:
89 return ERR_PTR(err);
90}
91
92struct ipc_namespace *copy_ipcs(unsigned long flags,
93 struct user_namespace *user_ns, struct ipc_namespace *ns)
94{
95 if (!(flags & CLONE_NEWIPC))
96 return get_ipc_ns(ns);
97 return create_ipc_ns(user_ns, ns);
98}
99
100/*
101 * free_ipcs - free all ipcs of one type
102 * @ns: the namespace to remove the ipcs from
103 * @ids: the table of ipcs to free
104 * @free: the function called to free each individual ipc
105 *
106 * Called for each kind of ipc when an ipc_namespace exits.
107 */
108void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
109 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
110{
111 struct kern_ipc_perm *perm;
112 int next_id;
113 int total, in_use;
114
115 down_write(&ids->rwsem);
116
117 in_use = ids->in_use;
118
119 for (total = 0, next_id = 0; total < in_use; next_id++) {
120 perm = idr_find(&ids->ipcs_idr, next_id);
121 if (perm == NULL)
122 continue;
123 rcu_read_lock();
124 ipc_lock_object(perm);
125 free(ns, perm);
126 total++;
127 }
128 up_write(&ids->rwsem);
129}
130
131static void free_ipc_ns(struct ipc_namespace *ns)
132{
133 /* mq_put_mnt() waits for a grace period as kern_unmount()
134 * uses synchronize_rcu().
135 */
136 mq_put_mnt(ns);
137 sem_exit_ns(ns);
138 msg_exit_ns(ns);
139 shm_exit_ns(ns);
140
141 retire_mq_sysctls(ns);
142 retire_ipc_sysctls(ns);
143
144 dec_ipc_namespaces(ns->ucounts);
145 put_user_ns(ns->user_ns);
146 ns_free_inum(&ns->ns);
147 kfree(ns);
148}
149
150static LLIST_HEAD(free_ipc_list);
151static void free_ipc(struct work_struct *unused)
152{
153 struct llist_node *node = llist_del_all(&free_ipc_list);
154 struct ipc_namespace *n, *t;
155
156 llist_for_each_entry_safe(n, t, node, mnt_llist)
157 free_ipc_ns(n);
158}
159
160/*
161 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
162 */
163static DECLARE_WORK(free_ipc_work, free_ipc);
164
165/*
166 * put_ipc_ns - drop a reference to an ipc namespace.
167 * @ns: the namespace to put
168 *
169 * If this is the last task in the namespace exiting, and
170 * it is dropping the refcount to 0, then it can race with
171 * a task in another ipc namespace but in a mounts namespace
172 * which has this ipcns's mqueuefs mounted, doing some action
173 * with one of the mqueuefs files. That can raise the refcount.
174 * So dropping the refcount, and raising the refcount when
175 * accessing it through the VFS, are protected with mq_lock.
176 *
177 * (Clearly, a task raising the refcount on its own ipc_ns
178 * needn't take mq_lock since it can't race with the last task
179 * in the ipcns exiting).
180 */
181void put_ipc_ns(struct ipc_namespace *ns)
182{
183 if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
184 mq_clear_sbinfo(ns);
185 spin_unlock(&mq_lock);
186
187 if (llist_add(&ns->mnt_llist, &free_ipc_list))
188 schedule_work(&free_ipc_work);
189 }
190}
191
192static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
193{
194 return container_of(ns, struct ipc_namespace, ns);
195}
196
197static struct ns_common *ipcns_get(struct task_struct *task)
198{
199 struct ipc_namespace *ns = NULL;
200 struct nsproxy *nsproxy;
201
202 task_lock(task);
203 nsproxy = task->nsproxy;
204 if (nsproxy)
205 ns = get_ipc_ns(nsproxy->ipc_ns);
206 task_unlock(task);
207
208 return ns ? &ns->ns : NULL;
209}
210
211static void ipcns_put(struct ns_common *ns)
212{
213 return put_ipc_ns(to_ipc_ns(ns));
214}
215
216static int ipcns_install(struct nsset *nsset, struct ns_common *new)
217{
218 struct nsproxy *nsproxy = nsset->nsproxy;
219 struct ipc_namespace *ns = to_ipc_ns(new);
220 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
221 !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
222 return -EPERM;
223
224 put_ipc_ns(nsproxy->ipc_ns);
225 nsproxy->ipc_ns = get_ipc_ns(ns);
226 return 0;
227}
228
229static struct user_namespace *ipcns_owner(struct ns_common *ns)
230{
231 return to_ipc_ns(ns)->user_ns;
232}
233
234const struct proc_ns_operations ipcns_operations = {
235 .name = "ipc",
236 .type = CLONE_NEWIPC,
237 .get = ipcns_get,
238 .put = ipcns_put,
239 .install = ipcns_install,
240 .owner = ipcns_owner,
241};