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/err.h> 14 15 #define USHRT_MAX 0xffff 16 #define SEQ_MULTIPLIER (IPCMNI) 17 18 void sem_init (void); 19 void msg_init (void); 20 void shm_init (void); 21 22 struct ipc_namespace; 23 24 void sem_init_ns(struct ipc_namespace *ns); 25 void msg_init_ns(struct ipc_namespace *ns); 26 void shm_init_ns(struct ipc_namespace *ns); 27 28 void sem_exit_ns(struct ipc_namespace *ns); 29 void msg_exit_ns(struct ipc_namespace *ns); 30 void shm_exit_ns(struct ipc_namespace *ns); 31 32 /* 33 * Structure that holds the parameters needed by the ipc operations 34 * (see after) 35 */ 36 struct ipc_params { 37 key_t key; 38 int flg; 39 union { 40 size_t size; /* for shared memories */ 41 int nsems; /* for semaphores */ 42 } u; /* holds the getnew() specific param */ 43 }; 44 45 /* 46 * Structure that holds some ipc operations. This structure is used to unify 47 * the calls to sys_msgget(), sys_semget(), sys_shmget() 48 * . routine to call to create a new ipc object. Can be one of newque, 49 * newary, newseg 50 * . routine to call to check permissions for a new ipc object. 51 * Can be one of security_msg_associate, security_sem_associate, 52 * security_shm_associate 53 * . routine to call for an extra check if needed 54 */ 55 struct ipc_ops { 56 int (*getnew) (struct ipc_namespace *, struct ipc_params *); 57 int (*associate) (struct kern_ipc_perm *, int); 58 int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *); 59 }; 60 61 struct seq_file; 62 struct ipc_ids; 63 64 void ipc_init_ids(struct ipc_ids *); 65 #ifdef CONFIG_PROC_FS 66 void __init ipc_init_proc_interface(const char *path, const char *header, 67 int ids, int (*show)(struct seq_file *, void *)); 68 #else 69 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) 70 #endif 71 72 #define IPC_SEM_IDS 0 73 #define IPC_MSG_IDS 1 74 #define IPC_SHM_IDS 2 75 76 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) 77 78 /* must be called with ids->rw_mutex acquired for writing */ 79 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); 80 81 /* must be called with ids->rw_mutex acquired for reading */ 82 int ipc_get_maxid(struct ipc_ids *); 83 84 /* must be called with both locks acquired. */ 85 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); 86 87 /* must be called with ipcp locked */ 88 int ipcperms(struct kern_ipc_perm *ipcp, short flg); 89 90 /* for rare, potentially huge allocations. 91 * both function can sleep 92 */ 93 void* ipc_alloc(int size); 94 void ipc_free(void* ptr, int size); 95 96 /* 97 * For allocation that need to be freed by RCU. 98 * Objects are reference counted, they start with reference count 1. 99 * getref increases the refcount, the putref call that reduces the recount 100 * to 0 schedules the rcu destruction. Caller must guarantee locking. 101 */ 102 void* ipc_rcu_alloc(int size); 103 void ipc_rcu_getref(void *ptr); 104 void ipc_rcu_putref(void *ptr); 105 106 /* 107 * ipc_lock_down: called with rw_mutex held 108 * ipc_lock: called without that lock held 109 */ 110 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int); 111 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); 112 113 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); 114 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); 115 116 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__) 117 /* On IA-64, we always use the "64-bit version" of the IPC structures. */ 118 # define ipc_parse_version(cmd) IPC_64 119 #else 120 int ipc_parse_version (int *cmd); 121 #endif 122 123 extern void free_msg(struct msg_msg *msg); 124 extern struct msg_msg *load_msg(const void __user *src, int len); 125 extern int store_msg(void __user *dest, struct msg_msg *msg, int len); 126 127 static inline int ipc_buildid(int id, int seq) 128 { 129 return SEQ_MULTIPLIER * seq + id; 130 } 131 132 /* 133 * Must be called with ipcp locked 134 */ 135 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) 136 { 137 if (uid / SEQ_MULTIPLIER != ipcp->seq) 138 return 1; 139 return 0; 140 } 141 142 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm) 143 { 144 rcu_read_lock(); 145 spin_lock(&perm->lock); 146 } 147 148 static inline void ipc_unlock(struct kern_ipc_perm *perm) 149 { 150 spin_unlock(&perm->lock); 151 rcu_read_unlock(); 152 } 153 154 struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id); 155 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id); 156 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 157 struct ipc_ops *ops, struct ipc_params *params); 158 159 #endif 160