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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 ucounts *inc_ipc_namespaces(struct user_namespace *ns)
20{
21 return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
22}
23
24static void dec_ipc_namespaces(struct ucounts *ucounts)
25{
26 dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
27}
28
29static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
30 struct ipc_namespace *old_ns)
31{
32 struct ipc_namespace *ns;
33 struct ucounts *ucounts;
34 int err;
35
36 err = -ENOSPC;
37 ucounts = inc_ipc_namespaces(user_ns);
38 if (!ucounts)
39 goto fail;
40
41 err = -ENOMEM;
42 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
43 if (ns == NULL)
44 goto fail_dec;
45
46 err = ns_alloc_inum(&ns->ns);
47 if (err)
48 goto fail_free;
49 ns->ns.ops = &ipcns_operations;
50
51 atomic_set(&ns->count, 1);
52 ns->user_ns = get_user_ns(user_ns);
53 ns->ucounts = ucounts;
54
55 err = mq_init_ns(ns);
56 if (err)
57 goto fail_put;
58
59 sem_init_ns(ns);
60 msg_init_ns(ns);
61 shm_init_ns(ns);
62
63 return ns;
64
65fail_put:
66 put_user_ns(ns->user_ns);
67 ns_free_inum(&ns->ns);
68fail_free:
69 kfree(ns);
70fail_dec:
71 dec_ipc_namespaces(ucounts);
72fail:
73 return ERR_PTR(err);
74}
75
76struct ipc_namespace *copy_ipcs(unsigned long flags,
77 struct user_namespace *user_ns, struct ipc_namespace *ns)
78{
79 if (!(flags & CLONE_NEWIPC))
80 return get_ipc_ns(ns);
81 return create_ipc_ns(user_ns, ns);
82}
83
84/*
85 * free_ipcs - free all ipcs of one type
86 * @ns: the namespace to remove the ipcs from
87 * @ids: the table of ipcs to free
88 * @free: the function called to free each individual ipc
89 *
90 * Called for each kind of ipc when an ipc_namespace exits.
91 */
92void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
93 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
94{
95 struct kern_ipc_perm *perm;
96 int next_id;
97 int total, in_use;
98
99 down_write(&ids->rwsem);
100
101 in_use = ids->in_use;
102
103 for (total = 0, next_id = 0; total < in_use; next_id++) {
104 perm = idr_find(&ids->ipcs_idr, next_id);
105 if (perm == NULL)
106 continue;
107 rcu_read_lock();
108 ipc_lock_object(perm);
109 free(ns, perm);
110 total++;
111 }
112 up_write(&ids->rwsem);
113}
114
115static void free_ipc_ns(struct ipc_namespace *ns)
116{
117 sem_exit_ns(ns);
118 msg_exit_ns(ns);
119 shm_exit_ns(ns);
120
121 dec_ipc_namespaces(ns->ucounts);
122 put_user_ns(ns->user_ns);
123 ns_free_inum(&ns->ns);
124 kfree(ns);
125}
126
127/*
128 * put_ipc_ns - drop a reference to an ipc namespace.
129 * @ns: the namespace to put
130 *
131 * If this is the last task in the namespace exiting, and
132 * it is dropping the refcount to 0, then it can race with
133 * a task in another ipc namespace but in a mounts namespace
134 * which has this ipcns's mqueuefs mounted, doing some action
135 * with one of the mqueuefs files. That can raise the refcount.
136 * So dropping the refcount, and raising the refcount when
137 * accessing it through the VFS, are protected with mq_lock.
138 *
139 * (Clearly, a task raising the refcount on its own ipc_ns
140 * needn't take mq_lock since it can't race with the last task
141 * in the ipcns exiting).
142 */
143void put_ipc_ns(struct ipc_namespace *ns)
144{
145 if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
146 mq_clear_sbinfo(ns);
147 spin_unlock(&mq_lock);
148 mq_put_mnt(ns);
149 free_ipc_ns(ns);
150 }
151}
152
153static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
154{
155 return container_of(ns, struct ipc_namespace, ns);
156}
157
158static struct ns_common *ipcns_get(struct task_struct *task)
159{
160 struct ipc_namespace *ns = NULL;
161 struct nsproxy *nsproxy;
162
163 task_lock(task);
164 nsproxy = task->nsproxy;
165 if (nsproxy)
166 ns = get_ipc_ns(nsproxy->ipc_ns);
167 task_unlock(task);
168
169 return ns ? &ns->ns : NULL;
170}
171
172static void ipcns_put(struct ns_common *ns)
173{
174 return put_ipc_ns(to_ipc_ns(ns));
175}
176
177static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
178{
179 struct ipc_namespace *ns = to_ipc_ns(new);
180 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
181 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
182 return -EPERM;
183
184 /* Ditch state from the old ipc namespace */
185 exit_sem(current);
186 put_ipc_ns(nsproxy->ipc_ns);
187 nsproxy->ipc_ns = get_ipc_ns(ns);
188 return 0;
189}
190
191static struct user_namespace *ipcns_owner(struct ns_common *ns)
192{
193 return to_ipc_ns(ns)->user_ns;
194}
195
196const struct proc_ns_operations ipcns_operations = {
197 .name = "ipc",
198 .type = CLONE_NEWIPC,
199 .get = ipcns_get,
200 .put = ipcns_put,
201 .install = ipcns_install,
202 .owner = ipcns_owner,
203};
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};