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 struct ipc_rcu { 51 struct rcu_head rcu; 52 atomic_t refcount; 53 } ____cacheline_aligned_in_smp; 54 55 #define ipc_rcu_to_struct(p) ((void *)(p+1)) 56 57 /* 58 * Structure that holds the parameters needed by the ipc operations 59 * (see after) 60 */ 61 struct ipc_params { 62 key_t key; 63 int flg; 64 union { 65 size_t size; /* for shared memories */ 66 int nsems; /* for semaphores */ 67 } u; /* holds the getnew() specific param */ 68 }; 69 70 /* 71 * Structure that holds some ipc operations. This structure is used to unify 72 * the calls to sys_msgget(), sys_semget(), sys_shmget() 73 * . routine to call to create a new ipc object. Can be one of newque, 74 * newary, newseg 75 * . routine to call to check permissions for a new ipc object. 76 * Can be one of security_msg_associate, security_sem_associate, 77 * security_shm_associate 78 * . routine to call for an extra check if needed 79 */ 80 struct ipc_ops { 81 int (*getnew)(struct ipc_namespace *, struct ipc_params *); 82 int (*associate)(struct kern_ipc_perm *, int); 83 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *); 84 }; 85 86 struct seq_file; 87 struct ipc_ids; 88 89 void ipc_init_ids(struct ipc_ids *); 90 #ifdef CONFIG_PROC_FS 91 void __init ipc_init_proc_interface(const char *path, const char *header, 92 int ids, int (*show)(struct seq_file *, void *)); 93 #else 94 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) 95 #endif 96 97 #define IPC_SEM_IDS 0 98 #define IPC_MSG_IDS 1 99 #define IPC_SHM_IDS 2 100 101 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) 102 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER) 103 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX) 104 105 /* must be called with ids->rwsem acquired for writing */ 106 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); 107 108 /* must be called with ids->rwsem acquired for reading */ 109 int ipc_get_maxid(struct ipc_ids *); 110 111 /* must be called with both locks acquired. */ 112 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); 113 114 /* must be called with ipcp locked */ 115 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg); 116 117 /* for rare, potentially huge allocations. 118 * both function can sleep 119 */ 120 void *ipc_alloc(int size); 121 void ipc_free(void *ptr); 122 123 /* 124 * For allocation that need to be freed by RCU. 125 * Objects are reference counted, they start with reference count 1. 126 * getref increases the refcount, the putref call that reduces the recount 127 * to 0 schedules the rcu destruction. Caller must guarantee locking. 128 */ 129 void *ipc_rcu_alloc(int size); 130 int ipc_rcu_getref(void *ptr); 131 void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head)); 132 void ipc_rcu_free(struct rcu_head *head); 133 134 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); 135 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id); 136 137 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); 138 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); 139 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); 140 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, 141 struct ipc_ids *ids, int id, int cmd, 142 struct ipc64_perm *perm, int extra_perm); 143 144 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 145 /* On IA-64, we always use the "64-bit version" of the IPC structures. */ 146 # define ipc_parse_version(cmd) IPC_64 147 #else 148 int ipc_parse_version(int *cmd); 149 #endif 150 151 extern void free_msg(struct msg_msg *msg); 152 extern struct msg_msg *load_msg(const void __user *src, size_t len); 153 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst); 154 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len); 155 156 extern void recompute_msgmni(struct ipc_namespace *); 157 158 static inline int ipc_buildid(int id, int seq) 159 { 160 return SEQ_MULTIPLIER * seq + id; 161 } 162 163 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) 164 { 165 return uid / SEQ_MULTIPLIER != ipcp->seq; 166 } 167 168 static inline void ipc_lock_object(struct kern_ipc_perm *perm) 169 { 170 spin_lock(&perm->lock); 171 } 172 173 static inline void ipc_unlock_object(struct kern_ipc_perm *perm) 174 { 175 spin_unlock(&perm->lock); 176 } 177 178 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm) 179 { 180 assert_spin_locked(&perm->lock); 181 } 182 183 static inline void ipc_unlock(struct kern_ipc_perm *perm) 184 { 185 ipc_unlock_object(perm); 186 rcu_read_unlock(); 187 } 188 189 /* 190 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths 191 * where the respective ipc_ids.rwsem is not being held down. 192 * Checks whether the ipc object is still around or if it's gone already, as 193 * ipc_rmid() may have already freed the ID while the ipc lock was spinning. 194 * Needs to be called with kern_ipc_perm.lock held -- exception made for one 195 * checkpoint case at sys_semtimedop() as noted in code commentary. 196 */ 197 static inline bool ipc_valid_object(struct kern_ipc_perm *perm) 198 { 199 return !perm->deleted; 200 } 201 202 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); 203 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 204 const struct ipc_ops *ops, struct ipc_params *params); 205 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, 206 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)); 207 #endif 208