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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 | static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns) | |
23 | { | |
24 | return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES); | |
25 | } | |
26 | ||
27 | static void dec_ipc_namespaces(struct ucounts *ucounts) | |
28 | { | |
29 | dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES); | |
30 | } | |
31 | ||
32 | static 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 | ||
74 | fail_destroy_shm: | |
75 | shm_exit_ns(ns); | |
76 | fail_destroy_msg: | |
77 | msg_exit_ns(ns); | |
78 | fail_destroy_sem: | |
79 | sem_exit_ns(ns); | |
80 | fail_put: | |
81 | put_user_ns(ns->user_ns); | |
82 | ns_free_inum(&ns->ns); | |
83 | fail_free: | |
84 | kfree(ns); | |
85 | fail_dec: | |
86 | dec_ipc_namespaces(ucounts); | |
87 | fail: | |
88 | return ERR_PTR(err); | |
89 | } | |
90 | ||
91 | struct 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 | */ | |
107 | void 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 | ||
130 | static 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 | */ | |
158 | void 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 | ||
168 | static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns) | |
169 | { | |
170 | return container_of(ns, struct ipc_namespace, ns); | |
171 | } | |
172 | ||
173 | static 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 | ||
187 | static void ipcns_put(struct ns_common *ns) | |
188 | { | |
189 | return put_ipc_ns(to_ipc_ns(ns)); | |
190 | } | |
191 | ||
192 | static 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 | ||
206 | static struct user_namespace *ipcns_owner(struct ns_common *ns) | |
207 | { | |
208 | return to_ipc_ns(ns)->user_ns; | |
209 | } | |
210 | ||
211 | const 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 | }; |