/* * linux/ipc/util.h * Copyright (C) 1999 Christoph Rohland * * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com> * namespaces support. 2006 OpenVZ, SWsoft Inc. * Pavel Emelianov <xemul@openvz.org> */ #ifndef _IPC_UTIL_H #define _IPC_UTIL_H #include <linux/idr.h> #include <linux/err.h> #define USHRT_MAX 0xffff #define SEQ_MULTIPLIER (IPCMNI) void sem_init (void); void msg_init (void); void shm_init (void); int sem_init_ns(struct ipc_namespace *ns); int msg_init_ns(struct ipc_namespace *ns); int shm_init_ns(struct ipc_namespace *ns); void sem_exit_ns(struct ipc_namespace *ns); void msg_exit_ns(struct ipc_namespace *ns); void shm_exit_ns(struct ipc_namespace *ns); struct ipc_ids { int in_use; unsigned short seq; unsigned short seq_max; struct rw_semaphore rw_mutex; struct idr ipcs_idr; }; /* * Structure that holds the parameters needed by the ipc operations * (see after) */ struct ipc_params { key_t key; int flg; union { size_t size; /* for shared memories */ int nsems; /* for semaphores */ } u; /* holds the getnew() specific param */ }; /* * Structure that holds some ipc operations. This structure is used to unify * the calls to sys_msgget(), sys_semget(), sys_shmget() * . routine to call to create a new ipc object. Can be one of newque, * newary, newseg * . routine to call to check permissions for a new ipc object. * Can be one of security_msg_associate, security_sem_associate, * security_shm_associate * . routine to call for an extra check if needed */ struct ipc_ops { int (*getnew) (struct ipc_namespace *, struct ipc_params *); int (*associate) (struct kern_ipc_perm *, int); int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *); }; struct seq_file; void ipc_init_ids(struct ipc_ids *); #ifdef CONFIG_PROC_FS void __init ipc_init_proc_interface(const char *path, const char *header, int ids, int (*show)(struct seq_file *, void *)); #else #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) #endif #define IPC_SEM_IDS 0 #define IPC_MSG_IDS 1 #define IPC_SHM_IDS 2 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) /* must be called with ids->rw_mutex acquired for writing */ int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); /* must be called with ids->rw_mutex acquired for reading */ int ipc_get_maxid(struct ipc_ids *); /* must be called with both locks acquired. */ void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); /* must be called with ipcp locked */ int ipcperms(struct kern_ipc_perm *ipcp, short flg); /* for rare, potentially huge allocations. * both function can sleep */ void* ipc_alloc(int size); void ipc_free(void* ptr, int size); /* * For allocation that need to be freed by RCU. * Objects are reference counted, they start with reference count 1. * getref increases the refcount, the putref call that reduces the recount * to 0 schedules the rcu destruction. Caller must guarantee locking. */ void* ipc_rcu_alloc(int size); void ipc_rcu_getref(void *ptr); void ipc_rcu_putref(void *ptr); /* * ipc_lock_down: called with rw_mutex held * ipc_lock: called without that lock held */ struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int); struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__) /* On IA-64, we always use the "64-bit version" of the IPC structures. */ # define ipc_parse_version(cmd) IPC_64 #else int ipc_parse_version (int *cmd); #endif extern void free_msg(struct msg_msg *msg); extern struct msg_msg *load_msg(const void __user *src, int len); extern int store_msg(void __user *dest, struct msg_msg *msg, int len); extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *, struct ipc_ops *, struct ipc_params *); extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *, struct ipc_ops *, struct ipc_params *); static inline int ipc_buildid(int id, int seq) { return SEQ_MULTIPLIER * seq + id; } /* * Must be called with ipcp locked */ static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) { if (uid / SEQ_MULTIPLIER != ipcp->seq) return 1; return 0; } static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm) { rcu_read_lock(); spin_lock(&perm->lock); } static inline void ipc_unlock(struct kern_ipc_perm *perm) { spin_unlock(&perm->lock); rcu_read_unlock(); } static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id) { struct kern_ipc_perm *out; out = ipc_lock_down(ids, id); if (IS_ERR(out)) return out; if (ipc_checkid(out, id)) { ipc_unlock(out); return ERR_PTR(-EIDRM); } return out; } static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id) { struct kern_ipc_perm *out; out = ipc_lock(ids, id); if (IS_ERR(out)) return out; if (ipc_checkid(out, id)) { ipc_unlock(out); return ERR_PTR(-EIDRM); } return out; } /** * ipcget - Common sys_*get() code * @ns : namsepace * @ids : IPC identifier set * @ops : operations to be called on ipc object creation, permission checks * and further checks * @params : the parameters needed by the previous operations. * * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). */ static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, struct ipc_ops *ops, struct ipc_params *params) { if (params->key == IPC_PRIVATE) return ipcget_new(ns, ids, ops, params); else return ipcget_public(ns, ids, ops, params); } #endif