the-tree/ipc/util.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * linux/ipc/util.h
0004  * Copyright (C) 1999 Christoph Rohland
0005  *
0006  * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
0007  * namespaces support.      2006 OpenVZ, SWsoft Inc.
0008  *                               Pavel Emelianov <xemul@openvz.org>
0009  */
0010
0011 #ifndef _IPC_UTIL_H
0012 #define _IPC_UTIL_H
0013
0014 #include <linux/unistd.h>
0015 #include <linux/err.h>
0016 #include <linux/ipc_namespace.h>
0017
0018 /*
0019  * The IPC ID contains 2 separate numbers - index and sequence number.
0020  * By default,
0021  *   bits  0-14: index (32k, 15 bits)
0022  *   bits 15-30: sequence number (64k, 16 bits)
0023  *
0024  * When IPCMNI extension mode is turned on, the composition changes:
0025  *   bits  0-23: index (16M, 24 bits)
0026  *   bits 24-30: sequence number (128, 7 bits)
0027  */
0028 #define IPCMNI_SHIFT        15
0029 #define IPCMNI_EXTEND_SHIFT 24
0030 #define IPCMNI_EXTEND_MIN_CYCLE (RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE)
0031 #define IPCMNI          (1 << IPCMNI_SHIFT)
0032 #define IPCMNI_EXTEND       (1 << IPCMNI_EXTEND_SHIFT)
0033
0034 #ifdef CONFIG_SYSVIPC_SYSCTL
0035 extern int ipc_mni;
0036 extern int ipc_mni_shift;
0037 extern int ipc_min_cycle;
0038
0039 #define ipcmni_seq_shift()  ipc_mni_shift
0040 #define IPCMNI_IDX_MASK     ((1 << ipc_mni_shift) - 1)
0041
0042 #else /* CONFIG_SYSVIPC_SYSCTL */
0043
0044 #define ipc_mni         IPCMNI
0045 #define ipc_min_cycle       ((int)RADIX_TREE_MAP_SIZE)
0046 #define ipcmni_seq_shift()  IPCMNI_SHIFT
0047 #define IPCMNI_IDX_MASK     ((1 << IPCMNI_SHIFT) - 1)
0048 #endif /* CONFIG_SYSVIPC_SYSCTL */
0049
0050 void sem_init(void);
0051 void msg_init(void);
0052 void shm_init(void);
0053
0054 struct ipc_namespace;
0055 struct pid_namespace;
0056
0057 #ifdef CONFIG_POSIX_MQUEUE
0058 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
0059 extern void mq_put_mnt(struct ipc_namespace *ns);
0060 #else
0061 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
0062 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
0063 #endif
0064
0065 #ifdef CONFIG_SYSVIPC
0066 void sem_init_ns(struct ipc_namespace *ns);
0067 void msg_init_ns(struct ipc_namespace *ns);
0068 void shm_init_ns(struct ipc_namespace *ns);
0069
0070 void sem_exit_ns(struct ipc_namespace *ns);
0071 void msg_exit_ns(struct ipc_namespace *ns);
0072 void shm_exit_ns(struct ipc_namespace *ns);
0073 #else
0074 static inline void sem_init_ns(struct ipc_namespace *ns) { }
0075 static inline void msg_init_ns(struct ipc_namespace *ns) { }
0076 static inline void shm_init_ns(struct ipc_namespace *ns) { }
0077
0078 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
0079 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
0080 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
0081 #endif
0082
0083 /*
0084  * Structure that holds the parameters needed by the ipc operations
0085  * (see after)
0086  */
0087 struct ipc_params {
0088     key_t key;
0089     int flg;
0090     union {
0091         size_t size;    /* for shared memories */
0092         int nsems;  /* for semaphores */
0093     } u;            /* holds the getnew() specific param */
0094 };
0095
0096 /*
0097  * Structure that holds some ipc operations. This structure is used to unify
0098  * the calls to sys_msgget(), sys_semget(), sys_shmget()
0099  *      . routine to call to create a new ipc object. Can be one of newque,
0100  *        newary, newseg
0101  *      . routine to call to check permissions for a new ipc object.
0102  *        Can be one of security_msg_associate, security_sem_associate,
0103  *        security_shm_associate
0104  *      . routine to call for an extra check if needed
0105  */
0106 struct ipc_ops {
0107     int (*getnew)(struct ipc_namespace *, struct ipc_params *);
0108     int (*associate)(struct kern_ipc_perm *, int);
0109     int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
0110 };
0111
0112 struct seq_file;
0113 struct ipc_ids;
0114
0115 void ipc_init_ids(struct ipc_ids *ids);
0116 #ifdef CONFIG_PROC_FS
0117 void __init ipc_init_proc_interface(const char *path, const char *header,
0118         int ids, int (*show)(struct seq_file *, void *));
0119 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
0120 #else
0121 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
0122 #endif
0123
0124 #define IPC_SEM_IDS 0
0125 #define IPC_MSG_IDS 1
0126 #define IPC_SHM_IDS 2
0127
0128 #define ipcid_to_idx(id)  ((id) & IPCMNI_IDX_MASK)
0129 #define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
0130 #define ipcid_seq_max()   (INT_MAX >> ipcmni_seq_shift())
0131
0132 /* must be called with ids->rwsem acquired for writing */
0133 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
0134
0135 /* must be called with both locks acquired. */
0136 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
0137
0138 /* must be called with both locks acquired. */
0139 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
0140
0141 /* must be called with ipcp locked */
0142 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
0143
0144 /**
0145  * ipc_get_maxidx - get the highest assigned index
0146  * @ids: ipc identifier set
0147  *
0148  * The function returns the highest assigned index for @ids. The function
0149  * doesn't scan the idr tree, it uses a cached value.
0150  *
0151  * Called with ipc_ids.rwsem held for reading.
0152  */
0153 static inline int ipc_get_maxidx(struct ipc_ids *ids)
0154 {
0155     if (ids->in_use == 0)
0156         return -1;
0157
0158     if (ids->in_use == ipc_mni)
0159         return ipc_mni - 1;
0160
0161     return ids->max_idx;
0162 }
0163
0164 /*
0165  * For allocation that need to be freed by RCU.
0166  * Objects are reference counted, they start with reference count 1.
0167  * getref increases the refcount, the putref call that reduces the recount
0168  * to 0 schedules the rcu destruction. Caller must guarantee locking.
0169  *
0170  * refcount is initialized by ipc_addid(), before that point call_rcu()
0171  * must be used.
0172  */
0173 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
0174 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
0175             void (*func)(struct rcu_head *head));
0176
0177 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
0178
0179 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
0180 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
0181 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
0182 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
0183                          struct ipc_ids *ids, int id, int cmd,
0184                          struct ipc64_perm *perm, int extra_perm);
0185
0186 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
0187 {
0188     struct pid *old = *pos;
0189     if (old != pid) {
0190         *pos = get_pid(pid);
0191         put_pid(old);
0192     }
0193 }
0194
0195 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
0196 int ipc_parse_version(int *cmd);
0197 #endif
0198
0199 extern void free_msg(struct msg_msg *msg);
0200 extern struct msg_msg *load_msg(const void __user *src, size_t len);
0201 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
0202 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
0203
0204 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
0205 {
0206     return ipcid_to_seqx(id) != ipcp->seq;
0207 }
0208
0209 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
0210 {
0211     spin_lock(&perm->lock);
0212 }
0213
0214 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
0215 {
0216     spin_unlock(&perm->lock);
0217 }
0218
0219 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
0220 {
0221     assert_spin_locked(&perm->lock);
0222 }
0223
0224 static inline void ipc_unlock(struct kern_ipc_perm *perm)
0225 {
0226     ipc_unlock_object(perm);
0227     rcu_read_unlock();
0228 }
0229
0230 /*
0231  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
0232  * where the respective ipc_ids.rwsem is not being held down.
0233  * Checks whether the ipc object is still around or if it's gone already, as
0234  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
0235  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
0236  * checkpoint case at sys_semtimedop() as noted in code commentary.
0237  */
0238 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
0239 {
0240     return !perm->deleted;
0241 }
0242
0243 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
0244 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
0245             const struct ipc_ops *ops, struct ipc_params *params);
0246 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
0247         void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
0248
0249 static inline int sem_check_semmni(struct ipc_namespace *ns) {
0250     /*
0251      * Check semmni range [0, ipc_mni]
0252      * semmni is the last element of sem_ctls[4] array
0253      */
0254     return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
0255         ? -ERANGE : 0;
0256 }
0257
0258 #ifdef CONFIG_COMPAT
0259 #include <linux/compat.h>
0260 struct compat_ipc_perm {
0261     key_t key;
0262     __compat_uid_t uid;
0263     __compat_gid_t gid;
0264     __compat_uid_t cuid;
0265     __compat_gid_t cgid;
0266     compat_mode_t mode;
0267     unsigned short seq;
0268 };
0269
0270 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
0271 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
0272 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
0273 int get_compat_ipc64_perm(struct ipc64_perm *,
0274               struct compat_ipc64_perm __user *);
0275
0276 static inline int compat_ipc_parse_version(int *cmd)
0277 {
0278     int version = *cmd & IPC_64;
0279     *cmd &= ~IPC_64;
0280     return version;
0281 }
0282
0283 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
0284 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
0285 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
0286             compat_long_t msgtyp, int msgflg);
0287 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
0288                compat_ssize_t msgsz, int msgflg);
0289 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
0290
0291 #endif
0292
0293 #endif