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
create_ipc_ns(struct user_namespace * user_ns,struct ipc_namespace * old_ns)19 static 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
copy_ipcs(unsigned long flags,struct user_namespace * user_ns,struct ipc_namespace * ns)54 struct 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 */
free_ipcs(struct ipc_namespace * ns,struct ipc_ids * ids,void (* free)(struct ipc_namespace *,struct kern_ipc_perm *))70 void 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
free_ipc_ns(struct ipc_namespace * ns)93 static 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 */
put_ipc_ns(struct ipc_namespace * ns)121 void 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
to_ipc_ns(struct ns_common * ns)131 static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
132 {
133 return container_of(ns, struct ipc_namespace, ns);
134 }
135
ipcns_get(struct task_struct * task)136 static 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
ipcns_put(struct ns_common * ns)150 static void ipcns_put(struct ns_common *ns)
151 {
152 return put_ipc_ns(to_ipc_ns(ns));
153 }
154
ipcns_install(struct nsproxy * nsproxy,struct ns_common * new)155 static 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
169 const 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 };
176