ipc/util.h

   1 /*
   2  * linux/ipc/util.h
   3  * Copyright (C) 1999 Christoph Rohland
   4  *
   5  * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
   6  * namespaces support.      2006 OpenVZ, SWsoft Inc.
   7  *                               Pavel Emelianov <xemul@openvz.org>
   8  */
   9
  10 #ifndef _IPC_UTIL_H
  11 #define _IPC_UTIL_H
  12
  13 #include <linux/idr.h>
  14 #include <linux/err.h>
  15
  16 #define USHRT_MAX 0xffff
  17 #define SEQ_MULTIPLIER  (IPCMNI)
  18
  19 void sem_init (void);
  20 void msg_init (void);
  21 void shm_init (void);
  22
  23 int sem_init_ns(struct ipc_namespace *ns);
  24 int msg_init_ns(struct ipc_namespace *ns);
  25 int shm_init_ns(struct ipc_namespace *ns);
  26
  27 void sem_exit_ns(struct ipc_namespace *ns);
  28 void msg_exit_ns(struct ipc_namespace *ns);
  29 void shm_exit_ns(struct ipc_namespace *ns);
  30
  31 struct ipc_ids {
  32         int in_use;
  33         unsigned short seq;
  34         unsigned short seq_max;
  35         struct mutex mutex;
  36         struct idr ipcs_idr;
  37 };
  38
  39 /*
  40  * Structure that holds the parameters needed by the ipc operations
  41  * (see after)
  42  */
  43 struct ipc_params {
  44         key_t key;
  45         int flg;
  46         union {
  47                 size_t size;    /* for shared memories */
  48                 int nsems;      /* for semaphores */
  49         } u;                    /* holds the getnew() specific param */
  50 };
  51
  52 /*
  53  * Structure that holds some ipc operations. This structure is used to unify
  54  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  55  *      . routine to call to create a new ipc object. Can be one of newque,
  56  *        newary, newseg
  57  *      . routine to call to check permissions for a new ipc object.
  58  *        Can be one of security_msg_associate, security_sem_associate,
  59  *        security_shm_associate
  60  *      . routine to call for an extra check if needed
  61  */
  62 struct ipc_ops {
  63         int (*getnew) (struct ipc_namespace *, struct ipc_params *);
  64         int (*associate) (struct kern_ipc_perm *, int);
  65         int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
  66 };
  67
  68 struct seq_file;
  69
  70 void ipc_init_ids(struct ipc_ids *);
  71 #ifdef CONFIG_PROC_FS
  72 void __init ipc_init_proc_interface(const char *path, const char *header,
  73                 int ids, int (*show)(struct seq_file *, void *));
  74 #else
  75 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  76 #endif
  77
  78 #define IPC_SEM_IDS     0
  79 #define IPC_MSG_IDS     1
  80 #define IPC_SHM_IDS     2
  81
  82 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  83
  84 /* must be called with ids->mutex acquired.*/
  85 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  86 int ipc_get_maxid(struct ipc_ids *);
  87
  88 /* must be called with both locks acquired. */
  89 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
  90
  91 /* must be called with ipcp locked */
  92 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
  93
  94 /* for rare, potentially huge allocations.
  95  * both function can sleep
  96  */
  97 void* ipc_alloc(int size);
  98 void ipc_free(void* ptr, int size);
  99
 100 /*
 101  * For allocation that need to be freed by RCU.
 102  * Objects are reference counted, they start with reference count 1.
 103  * getref increases the refcount, the putref call that reduces the recount
 104  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 105  */
 106 void* ipc_rcu_alloc(int size);
 107 void ipc_rcu_getref(void *ptr);
 108 void ipc_rcu_putref(void *ptr);
 109
 110 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 111
 112 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 113 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 114
 115 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 116   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 117 # define ipc_parse_version(cmd) IPC_64
 118 #else
 119 int ipc_parse_version (int *cmd);
 120 #endif
 121
 122 extern void free_msg(struct msg_msg *msg);
 123 extern struct msg_msg *load_msg(const void __user *src, int len);
 124 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 125 extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *,
 126                         struct ipc_ops *, struct ipc_params *);
 127 extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
 128                         struct ipc_ops *, struct ipc_params *);
 129
 130 static inline int ipc_buildid(struct ipc_ids *ids, int id, int seq)
 131 {
 132         return SEQ_MULTIPLIER * seq + id;
 133 }
 134
 135 /*
 136  * Must be called with ipcp locked
 137  */
 138 static inline int ipc_checkid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp,
 139                                 int uid)
 140 {
 141         if (uid / SEQ_MULTIPLIER != ipcp->seq)
 142                 return 1;
 143         return 0;
 144 }
 145
 146 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 147 {
 148         rcu_read_lock();
 149         spin_lock(&perm->lock);
 150 }
 151
 152 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 153 {
 154         spin_unlock(&perm->lock);
 155         rcu_read_unlock();
 156 }
 157
 158 static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
 159                                                 int id)
 160 {
 161         struct kern_ipc_perm *out;
 162
 163         out = ipc_lock(ids, id);
 164         if (IS_ERR(out))
 165                 return out;
 166
 167         if (ipc_checkid(ids, out, id)) {
 168                 ipc_unlock(out);
 169                 return ERR_PTR(-EIDRM);
 170         }
 171
 172         return out;
 173 }
 174
 175 /**
 176  * ipcget - Common sys_*get() code
 177  * @ns : namsepace
 178  * @ids : IPC identifier set
 179  * @ops : operations to be called on ipc object creation, permission checks
 180  *        and further checks
 181  * @params : the parameters needed by the previous operations.
 182  *
 183  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 184  */
 185 static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 186                         struct ipc_ops *ops, struct ipc_params *params)
 187 {
 188         if (params->key == IPC_PRIVATE)
 189                 return ipcget_new(ns, ids, ops, params);
 190         else
 191                 return ipcget_public(ns, ids, ops, params);
 192 }
 193
 194 #endif