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/unistd.h> 14 #include <linux/err.h> 15 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 #ifdef CONFIG_POSIX_MQUEUE 25 extern void mq_clear_sbinfo(struct ipc_namespace *ns); 26 extern void mq_put_mnt(struct ipc_namespace *ns); 27 #else 28 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { } 29 static inline void mq_put_mnt(struct ipc_namespace *ns) { } 30 #endif 31 32 #ifdef CONFIG_SYSVIPC 33 void sem_init_ns(struct ipc_namespace *ns); 34 void msg_init_ns(struct ipc_namespace *ns); 35 void shm_init_ns(struct ipc_namespace *ns); 36 37 void sem_exit_ns(struct ipc_namespace *ns); 38 void msg_exit_ns(struct ipc_namespace *ns); 39 void shm_exit_ns(struct ipc_namespace *ns); 40 #else 41 static inline void sem_init_ns(struct ipc_namespace *ns) { } 42 static inline void msg_init_ns(struct ipc_namespace *ns) { } 43 static inline void shm_init_ns(struct ipc_namespace *ns) { } 44 45 static inline void sem_exit_ns(struct ipc_namespace *ns) { } 46 static inline void msg_exit_ns(struct ipc_namespace *ns) { } 47 static inline void shm_exit_ns(struct ipc_namespace *ns) { } 48 #endif 49 50 /* 51 * Structure that holds the parameters needed by the ipc operations 52 * (see after) 53 */ 54 struct ipc_params { 55 key_t key; 56 int flg; 57 union { 58 size_t size; /* for shared memories */ 59 int nsems; /* for semaphores */ 60 } u; /* holds the getnew() specific param */ 61 }; 62 63 /* 64 * Structure that holds some ipc operations. This structure is used to unify 65 * the calls to sys_msgget(), sys_semget(), sys_shmget() 66 * . routine to call to create a new ipc object. Can be one of newque, 67 * newary, newseg 68 * . routine to call to check permissions for a new ipc object. 69 * Can be one of security_msg_associate, security_sem_associate, 70 * security_shm_associate 71 * . routine to call for an extra check if needed 72 */ 73 struct ipc_ops { 74 int (*getnew)(struct ipc_namespace *, struct ipc_params *); 75 int (*associate)(struct kern_ipc_perm *, int); 76 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *); 77 }; 78 79 struct seq_file; 80 struct ipc_ids; 81 82 void ipc_init_ids(struct ipc_ids *); 83 #ifdef CONFIG_PROC_FS 84 void __init ipc_init_proc_interface(const char *path, const char *header, 85 int ids, int (*show)(struct seq_file *, void *)); 86 #else 87 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) 88 #endif 89 90 #define IPC_SEM_IDS 0 91 #define IPC_MSG_IDS 1 92 #define IPC_SHM_IDS 2 93 94 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) 95 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER) 96 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX) 97 98 /* must be called with ids->rwsem acquired for writing */ 99 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); 100 101 /* must be called with ids->rwsem acquired for reading */ 102 int ipc_get_maxid(struct ipc_ids *); 103 104 /* must be called with both locks acquired. */ 105 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); 106 107 /* must be called with ipcp locked */ 108 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg); 109 110 /* 111 * For allocation that need to be freed by RCU. 112 * Objects are reference counted, they start with reference count 1. 113 * getref increases the refcount, the putref call that reduces the recount 114 * to 0 schedules the rcu destruction. Caller must guarantee locking. 115 * 116 * refcount is initialized by ipc_addid(), before that point call_rcu() 117 * must be used. 118 */ 119 int ipc_rcu_getref(struct kern_ipc_perm *ptr); 120 void ipc_rcu_putref(struct kern_ipc_perm *ptr, 121 void (*func)(struct rcu_head *head)); 122 123 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); 124 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id); 125 126 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); 127 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); 128 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); 129 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, 130 struct ipc_ids *ids, int id, int cmd, 131 struct ipc64_perm *perm, int extra_perm); 132 133 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 134 /* On IA-64, we always use the "64-bit version" of the IPC structures. */ 135 # define ipc_parse_version(cmd) IPC_64 136 #else 137 int ipc_parse_version(int *cmd); 138 #endif 139 140 extern void free_msg(struct msg_msg *msg); 141 extern struct msg_msg *load_msg(const void __user *src, size_t len); 142 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst); 143 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len); 144 145 static inline int ipc_buildid(int id, int seq) 146 { 147 return SEQ_MULTIPLIER * seq + id; 148 } 149 150 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) 151 { 152 return uid / SEQ_MULTIPLIER != ipcp->seq; 153 } 154 155 static inline void ipc_lock_object(struct kern_ipc_perm *perm) 156 { 157 spin_lock(&perm->lock); 158 } 159 160 static inline void ipc_unlock_object(struct kern_ipc_perm *perm) 161 { 162 spin_unlock(&perm->lock); 163 } 164 165 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm) 166 { 167 assert_spin_locked(&perm->lock); 168 } 169 170 static inline void ipc_unlock(struct kern_ipc_perm *perm) 171 { 172 ipc_unlock_object(perm); 173 rcu_read_unlock(); 174 } 175 176 /* 177 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths 178 * where the respective ipc_ids.rwsem is not being held down. 179 * Checks whether the ipc object is still around or if it's gone already, as 180 * ipc_rmid() may have already freed the ID while the ipc lock was spinning. 181 * Needs to be called with kern_ipc_perm.lock held -- exception made for one 182 * checkpoint case at sys_semtimedop() as noted in code commentary. 183 */ 184 static inline bool ipc_valid_object(struct kern_ipc_perm *perm) 185 { 186 return !perm->deleted; 187 } 188 189 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); 190 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 191 const struct ipc_ops *ops, struct ipc_params *params); 192 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, 193 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)); 194 #endif 195