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 rw_semaphore rw_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->rw_mutex acquired for writing */
  85 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  86
  87 /* must be called with ids->rw_mutex acquired for reading */
  88 int ipc_get_maxid(struct ipc_ids *);
  89
  90 /* must be called with both locks acquired. */
  91 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
  92
  93 /* must be called with ipcp locked */
  94 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
  95
  96 /* for rare, potentially huge allocations.
  97  * both function can sleep
  98  */
  99 void* ipc_alloc(int size);
 100 void ipc_free(void* ptr, int size);
 101
 102 /*
 103  * For allocation that need to be freed by RCU.
 104  * Objects are reference counted, they start with reference count 1.
 105  * getref increases the refcount, the putref call that reduces the recount
 106  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 107  */
 108 void* ipc_rcu_alloc(int size);
 109 void ipc_rcu_getref(void *ptr);
 110 void ipc_rcu_putref(void *ptr);
 111
 112 /*
 113  * ipc_lock_down: called with rw_mutex held
 114  * ipc_lock: called without that lock held
 115  */
 116 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 117 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 118
 119 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 120 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 121
 122 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 123   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 124 # define ipc_parse_version(cmd) IPC_64
 125 #else
 126 int ipc_parse_version (int *cmd);
 127 #endif
 128
 129 extern void free_msg(struct msg_msg *msg);
 130 extern struct msg_msg *load_msg(const void __user *src, int len);
 131 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 132 extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *,
 133                         struct ipc_ops *, struct ipc_params *);
 134 extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
 135                         struct ipc_ops *, struct ipc_params *);
 136
 137 static inline int ipc_buildid(int id, int seq)
 138 {
 139         return SEQ_MULTIPLIER * seq + id;
 140 }
 141
 142 /*
 143  * Must be called with ipcp locked
 144  */
 145 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 146 {
 147         if (uid / SEQ_MULTIPLIER != ipcp->seq)
 148                 return 1;
 149         return 0;
 150 }
 151
 152 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 153 {
 154         rcu_read_lock();
 155         spin_lock(&perm->lock);
 156 }
 157
 158 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 159 {
 160         spin_unlock(&perm->lock);
 161         rcu_read_unlock();
 162 }
 163
 164 static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
 165                                                 int id)
 166 {
 167         struct kern_ipc_perm *out;
 168
 169         out = ipc_lock_down(ids, id);
 170         if (IS_ERR(out))
 171                 return out;
 172
 173         if (ipc_checkid(out, id)) {
 174                 ipc_unlock(out);
 175                 return ERR_PTR(-EIDRM);
 176         }
 177
 178         return out;
 179 }
 180
 181 static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
 182                                                 int id)
 183 {
 184         struct kern_ipc_perm *out;
 185
 186         out = ipc_lock(ids, id);
 187         if (IS_ERR(out))
 188                 return out;
 189
 190         if (ipc_checkid(out, id)) {
 191                 ipc_unlock(out);
 192                 return ERR_PTR(-EIDRM);
 193         }
 194
 195         return out;
 196 }
 197
 198 /**
 199  * ipcget - Common sys_*get() code
 200  * @ns : namsepace
 201  * @ids : IPC identifier set
 202  * @ops : operations to be called on ipc object creation, permission checks
 203  *        and further checks
 204  * @params : the parameters needed by the previous operations.
 205  *
 206  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 207  */
 208 static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 209                         struct ipc_ops *ops, struct ipc_params *params)
 210 {
 211         if (params->key == IPC_PRIVATE)
 212                 return ipcget_new(ns, ids, ops, params);
 213         else
 214                 return ipcget_public(ns, ids, ops, params);
 215 }
 216
 217 #endif