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 struct ipc_namespace;
  24
  25 int sem_init_ns(struct ipc_namespace *ns);
  26 int msg_init_ns(struct ipc_namespace *ns);
  27 int shm_init_ns(struct ipc_namespace *ns);
  28
  29 void sem_exit_ns(struct ipc_namespace *ns);
  30 void msg_exit_ns(struct ipc_namespace *ns);
  31 void shm_exit_ns(struct ipc_namespace *ns);
  32
  33 struct ipc_ids {
  34         int in_use;
  35         unsigned short seq;
  36         unsigned short seq_max;
  37         struct rw_semaphore rw_mutex;
  38         struct idr ipcs_idr;
  39 };
  40
  41 /*
  42  * Structure that holds the parameters needed by the ipc operations
  43  * (see after)
  44  */
  45 struct ipc_params {
  46         key_t key;
  47         int flg;
  48         union {
  49                 size_t size;    /* for shared memories */
  50                 int nsems;      /* for semaphores */
  51         } u;                    /* holds the getnew() specific param */
  52 };
  53
  54 /*
  55  * Structure that holds some ipc operations. This structure is used to unify
  56  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  57  *      . routine to call to create a new ipc object. Can be one of newque,
  58  *        newary, newseg
  59  *      . routine to call to check permissions for a new ipc object.
  60  *        Can be one of security_msg_associate, security_sem_associate,
  61  *        security_shm_associate
  62  *      . routine to call for an extra check if needed
  63  */
  64 struct ipc_ops {
  65         int (*getnew) (struct ipc_namespace *, struct ipc_params *);
  66         int (*associate) (struct kern_ipc_perm *, int);
  67         int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
  68 };
  69
  70 struct seq_file;
  71
  72 void ipc_init_ids(struct ipc_ids *);
  73 #ifdef CONFIG_PROC_FS
  74 void __init ipc_init_proc_interface(const char *path, const char *header,
  75                 int ids, int (*show)(struct seq_file *, void *));
  76 #else
  77 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  78 #endif
  79
  80 #define IPC_SEM_IDS     0
  81 #define IPC_MSG_IDS     1
  82 #define IPC_SHM_IDS     2
  83
  84 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  85
  86 /* must be called with ids->rw_mutex acquired for writing */
  87 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  88
  89 /* must be called with ids->rw_mutex acquired for reading */
  90 int ipc_get_maxid(struct ipc_ids *);
  91
  92 /* must be called with both locks acquired. */
  93 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
  94
  95 /* must be called with ipcp locked */
  96 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
  97
  98 /* for rare, potentially huge allocations.
  99  * both function can sleep
 100  */
 101 void* ipc_alloc(int size);
 102 void ipc_free(void* ptr, int size);
 103
 104 /*
 105  * For allocation that need to be freed by RCU.
 106  * Objects are reference counted, they start with reference count 1.
 107  * getref increases the refcount, the putref call that reduces the recount
 108  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 109  */
 110 void* ipc_rcu_alloc(int size);
 111 void ipc_rcu_getref(void *ptr);
 112 void ipc_rcu_putref(void *ptr);
 113
 114 /*
 115  * ipc_lock_down: called with rw_mutex held
 116  * ipc_lock: called without that lock held
 117  */
 118 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 119 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 120
 121 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 122 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 123
 124 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 125   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 126 # define ipc_parse_version(cmd) IPC_64
 127 #else
 128 int ipc_parse_version (int *cmd);
 129 #endif
 130
 131 extern void free_msg(struct msg_msg *msg);
 132 extern struct msg_msg *load_msg(const void __user *src, int len);
 133 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 134 extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *,
 135                         struct ipc_ops *, struct ipc_params *);
 136 extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
 137                         struct ipc_ops *, struct ipc_params *);
 138
 139 static inline int ipc_buildid(int id, int seq)
 140 {
 141         return SEQ_MULTIPLIER * seq + id;
 142 }
 143
 144 /*
 145  * Must be called with ipcp locked
 146  */
 147 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 148 {
 149         if (uid / SEQ_MULTIPLIER != ipcp->seq)
 150                 return 1;
 151         return 0;
 152 }
 153
 154 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 155 {
 156         rcu_read_lock();
 157         spin_lock(&perm->lock);
 158 }
 159
 160 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 161 {
 162         spin_unlock(&perm->lock);
 163         rcu_read_unlock();
 164 }
 165
 166 static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
 167                                                 int id)
 168 {
 169         struct kern_ipc_perm *out;
 170
 171         out = ipc_lock_down(ids, id);
 172         if (IS_ERR(out))
 173                 return out;
 174
 175         if (ipc_checkid(out, id)) {
 176                 ipc_unlock(out);
 177                 return ERR_PTR(-EIDRM);
 178         }
 179
 180         return out;
 181 }
 182
 183 static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
 184                                                 int id)
 185 {
 186         struct kern_ipc_perm *out;
 187
 188         out = ipc_lock(ids, id);
 189         if (IS_ERR(out))
 190                 return out;
 191
 192         if (ipc_checkid(out, id)) {
 193                 ipc_unlock(out);
 194                 return ERR_PTR(-EIDRM);
 195         }
 196
 197         return out;
 198 }
 199
 200 /**
 201  * ipcget - Common sys_*get() code
 202  * @ns : namsepace
 203  * @ids : IPC identifier set
 204  * @ops : operations to be called on ipc object creation, permission checks
 205  *        and further checks
 206  * @params : the parameters needed by the previous operations.
 207  *
 208  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 209  */
 210 static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 211                         struct ipc_ops *ops, struct ipc_params *params)
 212 {
 213         if (params->key == IPC_PRIVATE)
 214                 return ipcget_new(ns, ids, ops, params);
 215         else
 216                 return ipcget_public(ns, ids, ops, params);
 217 }
 218
 219 #endif