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/*

 * linux/ipc/util.h

 * Copyright (C) 1999 Christoph Rohland

 *

 * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>

 * namespaces support.      2006 OpenVZ, SWsoft Inc.

 *                               Pavel Emelianov <xemul@openvz.org>

 */

#ifndef _IPC_UTIL_H

#define _IPC_UTIL_H

#include <linux/idr.h>

#include <linux/err.h>

#define USHRT_MAX 0xffff

#define SEQ_MULTIPLIER  (IPCMNI)

void sem_init (void);

void msg_init (void);

void shm_init (void);

int sem_init_ns(struct ipc_namespace *ns);

int msg_init_ns(struct ipc_namespace *ns);

int shm_init_ns(struct ipc_namespace *ns);

void sem_exit_ns(struct ipc_namespace *ns);

void msg_exit_ns(struct ipc_namespace *ns);

void shm_exit_ns(struct ipc_namespace *ns);

struct ipc_ids {

        int in_use;

        unsigned short seq;

        unsigned short seq_max;

        struct rw_semaphore rw_mutex;

        struct idr ipcs_idr;

};

/*

 * Structure that holds the parameters needed by the ipc operations

 * (see after)

 */

struct ipc_params {

        key_t key;

        int flg;

        union {

                size_t size;    /* for shared memories */

                int nsems;      /* for semaphores */

        } u;                    /* holds the getnew() specific param */

};

/*

 * Structure that holds some ipc operations. This structure is used to unify

 * the calls to sys_msgget(), sys_semget(), sys_shmget()

 *      . routine to call to create a new ipc object. Can be one of newque,

 *        newary, newseg

 *      . routine to call to check permissions for a new ipc object.

 *        Can be one of security_msg_associate, security_sem_associate,

 *        security_shm_associate

 *      . routine to call for an extra check if needed

 */

struct ipc_ops {

        int (*getnew) (struct ipc_namespace *, struct ipc_params *);

        int (*associate) (struct kern_ipc_perm *, int);

        int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);

};

struct seq_file;

void ipc_init_ids(struct ipc_ids *);

#ifdef CONFIG_PROC_FS

void __init ipc_init_proc_interface(const char *path, const char *header,

                int ids, int (*show)(struct seq_file *, void *));

#else

#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)

#endif

#define IPC_SEM_IDS     0

#define IPC_MSG_IDS     1

#define IPC_SHM_IDS     2

#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)

/* must be called with ids->rw_mutex acquired for writing */

int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);

/* must be called with ids->rw_mutex acquired for reading */

int ipc_get_maxid(struct ipc_ids *);

/* must be called with both locks acquired. */

void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);

/* must be called with ipcp locked */

int ipcperms(struct kern_ipc_perm *ipcp, short flg);

/* for rare, potentially huge allocations.

 * both function can sleep

 */

void* ipc_alloc(int size);

void ipc_free(void* ptr, int size);

/*

 * For allocation that need to be freed by RCU.

 * Objects are reference counted, they start with reference count 1.

 * getref increases the refcount, the putref call that reduces the recount

 * to 0 schedules the rcu destruction. Caller must guarantee locking.

 */

void* ipc_rcu_alloc(int size);

void ipc_rcu_getref(void *ptr);

void ipc_rcu_putref(void *ptr);

/*

 * ipc_lock_down: called with rw_mutex held

 * ipc_lock: called without that lock held

 */

struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);

struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);

void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);

void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);

#if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)

  /* On IA-64, we always use the "64-bit version" of the IPC structures.  */

# define ipc_parse_version(cmd) IPC_64

#else

int ipc_parse_version (int *cmd);

#endif

extern void free_msg(struct msg_msg *msg);

extern struct msg_msg *load_msg(const void __user *src, int len);

extern int store_msg(void __user *dest, struct msg_msg *msg, int len);

extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *,

                        struct ipc_ops *, struct ipc_params *);

extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,

                        struct ipc_ops *, struct ipc_params *);

static inline int ipc_buildid(int id, int seq)

{

        return SEQ_MULTIPLIER * seq + id;

}

/*

 * Must be called with ipcp locked

 */

static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)

{

        if (uid / SEQ_MULTIPLIER != ipcp->seq)

                return 1;

        return 0;

}

static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)

{

        rcu_read_lock();

        spin_lock(&perm->lock);

}

static inline void ipc_unlock(struct kern_ipc_perm *perm)

{

        spin_unlock(&perm->lock);

        rcu_read_unlock();

}

static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,

                                                int id)

{

        struct kern_ipc_perm *out;

        out = ipc_lock_down(ids, id);

        if (IS_ERR(out))

                return out;

        if (ipc_checkid(out, id)) {

                ipc_unlock(out);

                return ERR_PTR(-EIDRM);

        }

        return out;

}

static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,

                                                int id)

{

        struct kern_ipc_perm *out;

        out = ipc_lock(ids, id);

        if (IS_ERR(out))

                return out;

        if (ipc_checkid(out, id)) {

                ipc_unlock(out);

                return ERR_PTR(-EIDRM);

        }

        return out;

}

/**

 * ipcget - Common sys_*get() code

 * @ns : namsepace

 * @ids : IPC identifier set

 * @ops : operations to be called on ipc object creation, permission checks

 *        and further checks

 * @params : the parameters needed by the previous operations.

 *

 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().

 */

static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,

                        struct ipc_ops *ops, struct ipc_params *params)

{

        if (params->key == IPC_PRIVATE)

                return ipcget_new(ns, ids, ops, params);

        else

                return ipcget_public(ns, ids, ops, params);

}

#endif