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