/* * linux/ipc/util.c * Copyright (C) 1992 Krishna Balasubramanian * * Sep 1997 - Call suser() last after "normal" permission checks so we *            get BSD style process accounting right. *            Occurs in several places in the IPC code. *            Chris Evans, <chris@ferret.lmh.ox.ac.uk> * Nov 1999 - ipc helper functions, unified SMP locking *	      Manfred Spraul <manfred@colorfullife.com> * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary(). *            Mingming Cao <cmm@us.ibm.com> * Mar 2006 - support for audit of ipc object properties *            Dustin Kirkland <dustin.kirkland@us.ibm.com> * Jun 2006 - namespaces ssupport *            OpenVZ, SWsoft Inc. *            Pavel Emelianov <xemul@openvz.org> */ #include <linux/mm.h>#include <linux/shm.h>#include <linux/init.h>#include <linux/msg.h>#include <linux/smp_lock.h>#include <linux/vmalloc.h>#include <linux/slab.h>#include <linux/capability.h>#include <linux/highuid.h>#include <linux/security.h>#include <linux/rcupdate.h>#include <linux/workqueue.h>#include <linux/seq_file.h>#include <linux/proc_fs.h>#include <linux/audit.h>#include <linux/nsproxy.h> #include <asm/unistd.h> #include "util.h" struct ipc_proc_iface {	const char *path;	const char *header;	int ids;	int (*show)(struct seq_file *, void *);}; struct ipc_namespace init_ipc_ns = {	.kref = {		.refcount	= ATOMIC_INIT(2),	},}; #ifdef CONFIG_IPC_NSstatic struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns){	int err;	struct ipc_namespace *ns; 	err = -ENOMEM;	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);	if (ns == NULL)		goto err_mem; 	err = sem_init_ns(ns);	if (err)		goto err_sem;	err = msg_init_ns(ns);	if (err)		goto err_msg;	err = shm_init_ns(ns);	if (err)		goto err_shm; 	kref_init(&ns->kref);	return ns; err_shm:	msg_exit_ns(ns);err_msg:	sem_exit_ns(ns);err_sem:	kfree(ns);err_mem:	return ERR_PTR(err);} int unshare_ipcs(unsigned long unshare_flags, struct ipc_namespace **new_ipc){	struct ipc_namespace *new; 	if (unshare_flags & CLONE_NEWIPC) {		if (!capable(CAP_SYS_ADMIN))			return -EPERM; 		new = clone_ipc_ns(current->nsproxy->ipc_ns);		if (IS_ERR(new))			return PTR_ERR(new); 		*new_ipc = new;	} 	return 0;} int copy_ipcs(unsigned long flags, struct task_struct *tsk){	struct ipc_namespace *old_ns = tsk->nsproxy->ipc_ns;	struct ipc_namespace *new_ns;	int err = 0; 	if (!old_ns)		return 0; 	get_ipc_ns(old_ns); 	if (!(flags & CLONE_NEWIPC))		return 0; 	if (!capable(CAP_SYS_ADMIN)) {		err = -EPERM;		goto out;	} 	new_ns = clone_ipc_ns(old_ns);	if (!new_ns) {		err = -ENOMEM;		goto out;	} 	tsk->nsproxy->ipc_ns = new_ns;out:	put_ipc_ns(old_ns);	return err;} void free_ipc_ns(struct kref *kref){	struct ipc_namespace *ns; 	ns = container_of(kref, struct ipc_namespace, kref);	sem_exit_ns(ns);	msg_exit_ns(ns);	shm_exit_ns(ns);	kfree(ns);}#elseint copy_ipcs(unsigned long flags, struct task_struct *tsk){	if (flags & CLONE_NEWIPC)		return -EINVAL;	return 0;}#endif /** *	ipc_init	-	initialise IPC subsystem * *	The various system5 IPC resources (semaphores, messages and shared *	memory) are initialised */ static int __init ipc_init(void){	sem_init();	msg_init();	shm_init();	return 0;}__initcall(ipc_init); /** *	ipc_init_ids		-	initialise IPC identifiers *	@ids: Identifier set *	@size: Number of identifiers * *	Given a size for the ipc identifier range (limited below IPCMNI) *	set up the sequence range to use then allocate and initialise the *	array itself.  */ void __ipc_init ipc_init_ids(struct ipc_ids* ids, int size){	int i; 	mutex_init(&ids->mutex); 	if(size > IPCMNI)		size = IPCMNI;	ids->in_use = 0;	ids->max_id = -1;	ids->seq = 0;	{		int seq_limit = INT_MAX/SEQ_MULTIPLIER;		if(seq_limit > USHRT_MAX)			ids->seq_max = USHRT_MAX;		 else		 	ids->seq_max = seq_limit;	} 	ids->entries = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*size +				     sizeof(struct ipc_id_ary)); 	if(ids->entries == NULL) {		printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");		size = 0;		ids->entries = &ids->nullentry;	}	ids->entries->size = size;	for(i=0;i<size;i++)		ids->entries->p[i] = NULL;} #ifdef CONFIG_PROC_FSstatic const struct file_operations sysvipc_proc_fops;/** *	ipc_init_proc_interface	-  Create a proc interface for sysipc types using a seq_file interface. *	@path: Path in procfs *	@header: Banner to be printed at the beginning of the file. *	@ids: ipc id table to iterate. *	@show: show routine. */void __init ipc_init_proc_interface(const char *path, const char *header,		int ids, int (*show)(struct seq_file *, void *)){	struct proc_dir_entry *pde;	struct ipc_proc_iface *iface; 	iface = kmalloc(sizeof(*iface), GFP_KERNEL);	if (!iface)		return;	iface->path	= path;	iface->header	= header;	iface->ids	= ids;	iface->show	= show; 	pde = create_proc_entry(path,				S_IRUGO,        /* world readable */				NULL            /* parent dir */);	if (pde) {		pde->data = iface;		pde->proc_fops = &sysvipc_proc_fops;	} else {		kfree(iface);	}}#endif /** *	ipc_findkey	-	find a key in an ipc identifier set	 *	@ids: Identifier set *	@key: The key to find *	 *	Requires ipc_ids.mutex locked. *	Returns the identifier if found or -1 if not. */ int ipc_findkey(struct ipc_ids* ids, key_t key){	int id;	struct kern_ipc_perm* p;	int max_id = ids->max_id; 	/*	 * rcu_dereference() is not needed here	 * since ipc_ids.mutex is held	 */	for (id = 0; id <= max_id; id++) {		p = ids->entries->p[id];		if(p==NULL)			continue;		if (key == p->key)			return id;	}	return -1;} /* * Requires ipc_ids.mutex locked */static int grow_ary(struct ipc_ids* ids, int newsize){	struct ipc_id_ary* new;	struct ipc_id_ary* old;	int i;	int size = ids->entries->size; 	if(newsize > IPCMNI)		newsize = IPCMNI;	if(newsize <= size)		return newsize; 	new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +			    sizeof(struct ipc_id_ary));	if(new == NULL)		return size;	new->size = newsize;	memcpy(new->p, ids->entries->p, sizeof(struct kern_ipc_perm *)*size);	for(i=size;i<newsize;i++) {		new->p[i] = NULL;	}	old = ids->entries; 	/*	 * Use rcu_assign_pointer() to make sure the memcpyed contents	 * of the new array are visible before the new array becomes visible.	 */	rcu_assign_pointer(ids->entries, new); 	__ipc_fini_ids(ids, old);	return newsize;} /** *	ipc_addid 	-	add an IPC identifier *	@ids: IPC identifier set *	@new: new IPC permission set *	@size: new size limit for the id array * *	Add an entry 'new' to the IPC arrays. The permissions object is *	initialised and the first free entry is set up and the id assigned *	is returned. The list is returned in a locked state on success. *	On failure the list is not locked and -1 is returned. * *	Called with ipc_ids.mutex held. */ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size){	int id; 	size = grow_ary(ids,size); 	/*	 * rcu_dereference()() is not needed here since	 * ipc_ids.mutex is held	 */	for (id = 0; id < size; id++) {		if(ids->entries->p[id] == NULL)			goto found;	}	return -1;found:	ids->in_use++;	if (id > ids->max_id)		ids->max_id = id; 	new->cuid = new->uid = current->euid;	new->gid = new->cgid = current->egid; 	new->seq = ids->seq++;	if(ids->seq > ids->seq_max)		ids->seq = 0; 	spin_lock_init(&new->lock);	new->deleted = 0;	rcu_read_lock();	spin_lock(&new->lock);	ids->entries->p[id] = new;	return id;} /** *	ipc_rmid	-	remove an IPC identifier *	@ids: identifier set *	@id: Identifier to remove * *	The identifier must be valid, and in use. The kernel will panic if *	fed an invalid identifier. The entry is removed and internal *	variables recomputed. The object associated with the identifier *	is returned. *	ipc_ids.mutex and the spinlock for this ID is hold before this function *	is called, and remain locked on the exit. */ struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id){	struct kern_ipc_perm* p;	int lid = id % SEQ_MULTIPLIER;	BUG_ON(lid >= ids->entries->size); 	/* 	 * do not need a rcu_dereference()() here to force ordering	 * on Alpha, since the ipc_ids.mutex is held.	 */		p = ids->entries->p[lid];	ids->entries->p[lid] = NULL;	BUG_ON(p==NULL);	ids->in_use--; 	if (lid == ids->max_id) {		do {			lid--;			if(lid == -1)				break;		} while (ids->entries->p[lid] == NULL);		ids->max_id = lid;	}	p->deleted = 1;	return p;} /** *	ipc_alloc	-	allocate ipc space *	@size: size desired * *	Allocate memory from the appropriate pools and return a pointer to it. *	NULL is returned if the allocation fails */ void* ipc_alloc(int size){	void* out;	if(size > PAGE_SIZE)		out = vmalloc(size);	else		out = kmalloc(size, GFP_KERNEL);	return out;} /** *	ipc_free        -       free ipc space *	@ptr: pointer returned by ipc_alloc *	@size: size of block * *	Free a block created with ipc_alloc(). The caller must know the size *	used in the allocation call. */ void ipc_free(void* ptr, int size){	if(size > PAGE_SIZE)		vfree(ptr);	else		kfree(ptr);} /* * rcu allocations: * There are three headers that are prepended to the actual allocation: * - during use: ipc_rcu_hdr. * - during the rcu grace period: ipc_rcu_grace. * - [only if vmalloc]: ipc_rcu_sched. * Their lifetime doesn't overlap, thus the headers share the same memory. * Unlike a normal union, they are right-aligned, thus some container_of * forward/backward casting is necessary: */struct ipc_rcu_hdr{	int refcount;	int is_vmalloc;	void *data[0];};  struct ipc_rcu_grace{	struct rcu_head rcu;	/* "void *" makes sure alignment of following data is sane. */	void *data[0];}; struct ipc_rcu_sched{	struct work_struct work;	/* "void *" makes sure alignment of following data is sane. */	void *data[0];}; #define HDRLEN_KMALLOC		(sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \					sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))#define HDRLEN_VMALLOC		(sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \					sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC) static inline int rcu_use_vmalloc(int size){	/* Too big for a single page? */	if (HDRLEN_KMALLOC + size > PAGE_SIZE)		return 1;	return 0;} /** *	ipc_rcu_alloc	-	allocate ipc and rcu space  *	@size: size desired * *	Allocate memory for the rcu header structure +  the object. *	Returns the pointer to the object. *	NULL is returned if the allocation fails.  */ void* ipc_rcu_alloc(int size){	void* out;	/* 	 * We prepend the allocation with the rcu struct, and	 * workqueue if necessary (for vmalloc). 	 */	if (rcu_use_vmalloc(size)) {		out = vmalloc(HDRLEN_VMALLOC + size);

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