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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * linux/ipc/util.h
4 * Copyright (C) 1999 Christoph Rohland
5 *
6 * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
7 * namespaces support. 2006 OpenVZ, SWsoft Inc.
8 * Pavel Emelianov <xemul@openvz.org>
9 */
10
11#ifndef _IPC_UTIL_H
12#define _IPC_UTIL_H
13
14#include <linux/unistd.h>
15#include <linux/err.h>
16#include <linux/ipc_namespace.h>
17
18#define SEQ_MULTIPLIER (IPCMNI)
19
20int sem_init(void);
21int msg_init(void);
22void shm_init(void);
23
24struct ipc_namespace;
25
26#ifdef CONFIG_POSIX_MQUEUE
27extern void mq_clear_sbinfo(struct ipc_namespace *ns);
28extern void mq_put_mnt(struct ipc_namespace *ns);
29#else
30static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
31static inline void mq_put_mnt(struct ipc_namespace *ns) { }
32#endif
33
34#ifdef CONFIG_SYSVIPC
35int sem_init_ns(struct ipc_namespace *ns);
36int msg_init_ns(struct ipc_namespace *ns);
37int shm_init_ns(struct ipc_namespace *ns);
38
39void sem_exit_ns(struct ipc_namespace *ns);
40void msg_exit_ns(struct ipc_namespace *ns);
41void shm_exit_ns(struct ipc_namespace *ns);
42#else
43static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
44static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
45static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
46
47static inline void sem_exit_ns(struct ipc_namespace *ns) { }
48static inline void msg_exit_ns(struct ipc_namespace *ns) { }
49static inline void shm_exit_ns(struct ipc_namespace *ns) { }
50#endif
51
52/*
53 * Structure that holds the parameters needed by the ipc operations
54 * (see after)
55 */
56struct ipc_params {
57 key_t key;
58 int flg;
59 union {
60 size_t size; /* for shared memories */
61 int nsems; /* for semaphores */
62 } u; /* holds the getnew() specific param */
63};
64
65/*
66 * Structure that holds some ipc operations. This structure is used to unify
67 * the calls to sys_msgget(), sys_semget(), sys_shmget()
68 * . routine to call to create a new ipc object. Can be one of newque,
69 * newary, newseg
70 * . routine to call to check permissions for a new ipc object.
71 * Can be one of security_msg_associate, security_sem_associate,
72 * security_shm_associate
73 * . routine to call for an extra check if needed
74 */
75struct ipc_ops {
76 int (*getnew)(struct ipc_namespace *, struct ipc_params *);
77 int (*associate)(struct kern_ipc_perm *, int);
78 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
79};
80
81struct seq_file;
82struct ipc_ids;
83
84int ipc_init_ids(struct ipc_ids *);
85#ifdef CONFIG_PROC_FS
86void __init ipc_init_proc_interface(const char *path, const char *header,
87 int ids, int (*show)(struct seq_file *, void *));
88#else
89#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
90#endif
91
92#define IPC_SEM_IDS 0
93#define IPC_MSG_IDS 1
94#define IPC_SHM_IDS 2
95
96#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
97#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
98#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
99
100/* must be called with ids->rwsem acquired for writing */
101int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
102
103/* must be called with both locks acquired. */
104void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
105
106/* must be called with both locks acquired. */
107void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
108
109/* must be called with ipcp locked */
110int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
111
112/**
113 * ipc_get_maxid - get the last assigned id
114 * @ids: ipc identifier set
115 *
116 * Called with ipc_ids.rwsem held for reading.
117 */
118static inline int ipc_get_maxid(struct ipc_ids *ids)
119{
120 if (ids->in_use == 0)
121 return -1;
122
123 if (ids->in_use == IPCMNI)
124 return IPCMNI - 1;
125
126 return ids->max_id;
127}
128
129/*
130 * For allocation that need to be freed by RCU.
131 * Objects are reference counted, they start with reference count 1.
132 * getref increases the refcount, the putref call that reduces the recount
133 * to 0 schedules the rcu destruction. Caller must guarantee locking.
134 *
135 * refcount is initialized by ipc_addid(), before that point call_rcu()
136 * must be used.
137 */
138int ipc_rcu_getref(struct kern_ipc_perm *ptr);
139void ipc_rcu_putref(struct kern_ipc_perm *ptr,
140 void (*func)(struct rcu_head *head));
141
142struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
143struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
144
145void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
146void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
147int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
148struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
149 struct ipc_ids *ids, int id, int cmd,
150 struct ipc64_perm *perm, int extra_perm);
151
152#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
153/* On IA-64, we always use the "64-bit version" of the IPC structures. */
154# define ipc_parse_version(cmd) IPC_64
155#else
156int ipc_parse_version(int *cmd);
157#endif
158
159extern void free_msg(struct msg_msg *msg);
160extern struct msg_msg *load_msg(const void __user *src, size_t len);
161extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
162extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
163
164static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
165{
166 return uid / SEQ_MULTIPLIER != ipcp->seq;
167}
168
169static inline void ipc_lock_object(struct kern_ipc_perm *perm)
170{
171 spin_lock(&perm->lock);
172}
173
174static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
175{
176 spin_unlock(&perm->lock);
177}
178
179static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
180{
181 assert_spin_locked(&perm->lock);
182}
183
184static inline void ipc_unlock(struct kern_ipc_perm *perm)
185{
186 ipc_unlock_object(perm);
187 rcu_read_unlock();
188}
189
190/*
191 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
192 * where the respective ipc_ids.rwsem is not being held down.
193 * Checks whether the ipc object is still around or if it's gone already, as
194 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
195 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
196 * checkpoint case at sys_semtimedop() as noted in code commentary.
197 */
198static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
199{
200 return !perm->deleted;
201}
202
203struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
204int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
205 const struct ipc_ops *ops, struct ipc_params *params);
206void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
207 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
208
209#ifdef CONFIG_COMPAT
210#include <linux/compat.h>
211struct compat_ipc_perm {
212 key_t key;
213 __compat_uid_t uid;
214 __compat_gid_t gid;
215 __compat_uid_t cuid;
216 __compat_gid_t cgid;
217 compat_mode_t mode;
218 unsigned short seq;
219};
220
221void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
222void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
223int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
224int get_compat_ipc64_perm(struct ipc64_perm *,
225 struct compat_ipc64_perm __user *);
226
227static inline int compat_ipc_parse_version(int *cmd)
228{
229#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
230 int version = *cmd & IPC_64;
231 *cmd &= ~IPC_64;
232 return version;
233#else
234 return IPC_64;
235#endif
236}
237#endif
238#endif