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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 = kmalloc(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 = sem_init_ns(ns);
59 if (err)
60 goto fail_put;
61 err = msg_init_ns(ns);
62 if (err)
63 goto fail_destroy_sem;
64 err = shm_init_ns(ns);
65 if (err)
66 goto fail_destroy_msg;
67
68 err = mq_init_ns(ns);
69 if (err)
70 goto fail_destroy_shm;
71
72 return ns;
73
74fail_destroy_shm:
75 shm_exit_ns(ns);
76fail_destroy_msg:
77 msg_exit_ns(ns);
78fail_destroy_sem:
79 sem_exit_ns(ns);
80fail_put:
81 put_user_ns(ns->user_ns);
82 ns_free_inum(&ns->ns);
83fail_free:
84 kfree(ns);
85fail_dec:
86 dec_ipc_namespaces(ucounts);
87fail:
88 return ERR_PTR(err);
89}
90
91struct ipc_namespace *copy_ipcs(unsigned long flags,
92 struct user_namespace *user_ns, struct ipc_namespace *ns)
93{
94 if (!(flags & CLONE_NEWIPC))
95 return get_ipc_ns(ns);
96 return create_ipc_ns(user_ns, ns);
97}
98
99/*
100 * free_ipcs - free all ipcs of one type
101 * @ns: the namespace to remove the ipcs from
102 * @ids: the table of ipcs to free
103 * @free: the function called to free each individual ipc
104 *
105 * Called for each kind of ipc when an ipc_namespace exits.
106 */
107void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
108 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
109{
110 struct kern_ipc_perm *perm;
111 int next_id;
112 int total, in_use;
113
114 down_write(&ids->rwsem);
115
116 in_use = ids->in_use;
117
118 for (total = 0, next_id = 0; total < in_use; next_id++) {
119 perm = idr_find(&ids->ipcs_idr, next_id);
120 if (perm == NULL)
121 continue;
122 rcu_read_lock();
123 ipc_lock_object(perm);
124 free(ns, perm);
125 total++;
126 }
127 up_write(&ids->rwsem);
128}
129
130static void free_ipc_ns(struct ipc_namespace *ns)
131{
132 sem_exit_ns(ns);
133 msg_exit_ns(ns);
134 shm_exit_ns(ns);
135
136 dec_ipc_namespaces(ns->ucounts);
137 put_user_ns(ns->user_ns);
138 ns_free_inum(&ns->ns);
139 kfree(ns);
140}
141
142/*
143 * put_ipc_ns - drop a reference to an ipc namespace.
144 * @ns: the namespace to put
145 *
146 * If this is the last task in the namespace exiting, and
147 * it is dropping the refcount to 0, then it can race with
148 * a task in another ipc namespace but in a mounts namespace
149 * which has this ipcns's mqueuefs mounted, doing some action
150 * with one of the mqueuefs files. That can raise the refcount.
151 * So dropping the refcount, and raising the refcount when
152 * accessing it through the VFS, are protected with mq_lock.
153 *
154 * (Clearly, a task raising the refcount on its own ipc_ns
155 * needn't take mq_lock since it can't race with the last task
156 * in the ipcns exiting).
157 */
158void put_ipc_ns(struct ipc_namespace *ns)
159{
160 if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
161 mq_clear_sbinfo(ns);
162 spin_unlock(&mq_lock);
163 mq_put_mnt(ns);
164 free_ipc_ns(ns);
165 }
166}
167
168static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
169{
170 return container_of(ns, struct ipc_namespace, ns);
171}
172
173static struct ns_common *ipcns_get(struct task_struct *task)
174{
175 struct ipc_namespace *ns = NULL;
176 struct nsproxy *nsproxy;
177
178 task_lock(task);
179 nsproxy = task->nsproxy;
180 if (nsproxy)
181 ns = get_ipc_ns(nsproxy->ipc_ns);
182 task_unlock(task);
183
184 return ns ? &ns->ns : NULL;
185}
186
187static void ipcns_put(struct ns_common *ns)
188{
189 return put_ipc_ns(to_ipc_ns(ns));
190}
191
192static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
193{
194 struct ipc_namespace *ns = to_ipc_ns(new);
195 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
196 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
197 return -EPERM;
198
199 /* Ditch state from the old ipc namespace */
200 exit_sem(current);
201 put_ipc_ns(nsproxy->ipc_ns);
202 nsproxy->ipc_ns = get_ipc_ns(ns);
203 return 0;
204}
205
206static struct user_namespace *ipcns_owner(struct ns_common *ns)
207{
208 return to_ipc_ns(ns)->user_ns;
209}
210
211const struct proc_ns_operations ipcns_operations = {
212 .name = "ipc",
213 .type = CLONE_NEWIPC,
214 .get = ipcns_get,
215 .put = ipcns_put,
216 .install = ipcns_install,
217 .owner = ipcns_owner,
218};