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 218