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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/*
19 * The IPC ID contains 2 separate numbers - index and sequence number.
20 * By default,
21 * bits 0-14: index (32k, 15 bits)
22 * bits 15-30: sequence number (64k, 16 bits)
23 *
24 * When IPCMNI extension mode is turned on, the composition changes:
25 * bits 0-23: index (16M, 24 bits)
26 * bits 24-30: sequence number (128, 7 bits)
27 */
28#define IPCMNI_SHIFT 15
29#define IPCMNI_EXTEND_SHIFT 24
30#define IPCMNI_EXTEND_MIN_CYCLE (RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE)
31#define IPCMNI (1 << IPCMNI_SHIFT)
32#define IPCMNI_EXTEND (1 << IPCMNI_EXTEND_SHIFT)
33
34#ifdef CONFIG_SYSVIPC_SYSCTL
35extern int ipc_mni;
36extern int ipc_mni_shift;
37extern int ipc_min_cycle;
38
39#define ipcmni_seq_shift() ipc_mni_shift
40#define IPCMNI_IDX_MASK ((1 << ipc_mni_shift) - 1)
41
42#else /* CONFIG_SYSVIPC_SYSCTL */
43
44#define ipc_mni IPCMNI
45#define ipc_min_cycle ((int)RADIX_TREE_MAP_SIZE)
46#define ipcmni_seq_shift() IPCMNI_SHIFT
47#define IPCMNI_IDX_MASK ((1 << IPCMNI_SHIFT) - 1)
48#endif /* CONFIG_SYSVIPC_SYSCTL */
49
50void sem_init(void);
51void msg_init(void);
52void shm_init(void);
53
54struct ipc_namespace;
55struct pid_namespace;
56
57#ifdef CONFIG_POSIX_MQUEUE
58extern void mq_clear_sbinfo(struct ipc_namespace *ns);
59extern void mq_put_mnt(struct ipc_namespace *ns);
60#else
61static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
62static inline void mq_put_mnt(struct ipc_namespace *ns) { }
63#endif
64
65#ifdef CONFIG_SYSVIPC
66void sem_init_ns(struct ipc_namespace *ns);
67void msg_init_ns(struct ipc_namespace *ns);
68void shm_init_ns(struct ipc_namespace *ns);
69
70void sem_exit_ns(struct ipc_namespace *ns);
71void msg_exit_ns(struct ipc_namespace *ns);
72void shm_exit_ns(struct ipc_namespace *ns);
73#else
74static inline void sem_init_ns(struct ipc_namespace *ns) { }
75static inline void msg_init_ns(struct ipc_namespace *ns) { }
76static inline void shm_init_ns(struct ipc_namespace *ns) { }
77
78static inline void sem_exit_ns(struct ipc_namespace *ns) { }
79static inline void msg_exit_ns(struct ipc_namespace *ns) { }
80static inline void shm_exit_ns(struct ipc_namespace *ns) { }
81#endif
82
83/*
84 * Structure that holds the parameters needed by the ipc operations
85 * (see after)
86 */
87struct ipc_params {
88 key_t key;
89 int flg;
90 union {
91 size_t size; /* for shared memories */
92 int nsems; /* for semaphores */
93 } u; /* holds the getnew() specific param */
94};
95
96/*
97 * Structure that holds some ipc operations. This structure is used to unify
98 * the calls to sys_msgget(), sys_semget(), sys_shmget()
99 * . routine to call to create a new ipc object. Can be one of newque,
100 * newary, newseg
101 * . routine to call to check permissions for a new ipc object.
102 * Can be one of security_msg_associate, security_sem_associate,
103 * security_shm_associate
104 * . routine to call for an extra check if needed
105 */
106struct ipc_ops {
107 int (*getnew)(struct ipc_namespace *, struct ipc_params *);
108 int (*associate)(struct kern_ipc_perm *, int);
109 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
110};
111
112struct seq_file;
113struct ipc_ids;
114
115void ipc_init_ids(struct ipc_ids *ids);
116#ifdef CONFIG_PROC_FS
117void __init ipc_init_proc_interface(const char *path, const char *header,
118 int ids, int (*show)(struct seq_file *, void *));
119struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
120#else
121#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
122#endif
123
124#define IPC_SEM_IDS 0
125#define IPC_MSG_IDS 1
126#define IPC_SHM_IDS 2
127
128#define ipcid_to_idx(id) ((id) & IPCMNI_IDX_MASK)
129#define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
130#define ipcid_seq_max() (INT_MAX >> ipcmni_seq_shift())
131
132/* must be called with ids->rwsem acquired for writing */
133int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
134
135/* must be called with both locks acquired. */
136void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
137
138/* must be called with both locks acquired. */
139void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
140
141/* must be called with ipcp locked */
142int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
143
144/**
145 * ipc_get_maxidx - get the highest assigned index
146 * @ids: ipc identifier set
147 *
148 * Called with ipc_ids.rwsem held for reading.
149 */
150static inline int ipc_get_maxidx(struct ipc_ids *ids)
151{
152 if (ids->in_use == 0)
153 return -1;
154
155 if (ids->in_use == ipc_mni)
156 return ipc_mni - 1;
157
158 return ids->max_idx;
159}
160
161/*
162 * For allocation that need to be freed by RCU.
163 * Objects are reference counted, they start with reference count 1.
164 * getref increases the refcount, the putref call that reduces the recount
165 * to 0 schedules the rcu destruction. Caller must guarantee locking.
166 *
167 * refcount is initialized by ipc_addid(), before that point call_rcu()
168 * must be used.
169 */
170bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
171void ipc_rcu_putref(struct kern_ipc_perm *ptr,
172 void (*func)(struct rcu_head *head));
173
174struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
175
176void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
177void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
178int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
179struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
180 struct ipc_ids *ids, int id, int cmd,
181 struct ipc64_perm *perm, int extra_perm);
182
183static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
184{
185 struct pid *old = *pos;
186 if (old != pid) {
187 *pos = get_pid(pid);
188 put_pid(old);
189 }
190}
191
192#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
193int ipc_parse_version(int *cmd);
194#endif
195
196extern void free_msg(struct msg_msg *msg);
197extern struct msg_msg *load_msg(const void __user *src, size_t len);
198extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
199extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
200
201static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
202{
203 return ipcid_to_seqx(id) != ipcp->seq;
204}
205
206static inline void ipc_lock_object(struct kern_ipc_perm *perm)
207{
208 spin_lock(&perm->lock);
209}
210
211static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
212{
213 spin_unlock(&perm->lock);
214}
215
216static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
217{
218 assert_spin_locked(&perm->lock);
219}
220
221static inline void ipc_unlock(struct kern_ipc_perm *perm)
222{
223 ipc_unlock_object(perm);
224 rcu_read_unlock();
225}
226
227/*
228 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
229 * where the respective ipc_ids.rwsem is not being held down.
230 * Checks whether the ipc object is still around or if it's gone already, as
231 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
232 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
233 * checkpoint case at sys_semtimedop() as noted in code commentary.
234 */
235static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
236{
237 return !perm->deleted;
238}
239
240struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
241int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
242 const struct ipc_ops *ops, struct ipc_params *params);
243void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
244 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
245
246static inline int sem_check_semmni(struct ipc_namespace *ns) {
247 /*
248 * Check semmni range [0, ipc_mni]
249 * semmni is the last element of sem_ctls[4] array
250 */
251 return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
252 ? -ERANGE : 0;
253}
254
255#ifdef CONFIG_COMPAT
256#include <linux/compat.h>
257struct compat_ipc_perm {
258 key_t key;
259 __compat_uid_t uid;
260 __compat_gid_t gid;
261 __compat_uid_t cuid;
262 __compat_gid_t cgid;
263 compat_mode_t mode;
264 unsigned short seq;
265};
266
267void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
268void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
269int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
270int get_compat_ipc64_perm(struct ipc64_perm *,
271 struct compat_ipc64_perm __user *);
272
273static inline int compat_ipc_parse_version(int *cmd)
274{
275 int version = *cmd & IPC_64;
276 *cmd &= ~IPC_64;
277 return version;
278}
279
280long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
281long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
282long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
283 compat_long_t msgtyp, int msgflg);
284long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
285 compat_ssize_t msgsz, int msgflg);
286long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
287
288#endif
289
290#endif