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[apple/xnu.git] / osfmk / ipc / ipc_object.h

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/*
 * @OSF_COPYRIGHT@
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/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 * NOTICE: This file was modified by McAfee Research in 2004 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */
/*
 */
/*
 *	File:	ipc/ipc_object.h
 *	Author:	Rich Draves
 *	Date:	1989
 *
 *	Definitions for IPC objects, for which tasks have capabilities.
 */

#ifndef	_IPC_IPC_OBJECT_H_
#define _IPC_IPC_OBJECT_H_

#include <mach_rt.h>

#include <mach/kern_return.h>
#include <mach/message.h>
#include <kern/locks.h>
#include <kern/macro_help.h>
#include <kern/assert.h>
#include <kern/zalloc.h>
#include <ipc/ipc_types.h>
#include <libkern/OSAtomic.h>

typedef natural_t ipc_object_refs_t;	/* for ipc/ipc_object.h		*/
typedef natural_t ipc_object_bits_t;
typedef natural_t ipc_object_type_t;

/*
 * The ipc_object is used to both tag and reference count these two data
 * structures, and (Noto Bene!) pointers to either of these or the
 * ipc_object at the head of these are freely cast back and forth; hence
 * the ipc_object MUST BE FIRST in the ipc_common_data.
 * 
 * If the RPC implementation enabled user-mode code to use kernel-level
 * data structures (as ours used to), this peculiar structuring would
 * avoid having anything in user code depend on the kernel configuration
 * (with which lock size varies).
 */
struct ipc_object {
	ipc_object_bits_t io_bits;
	ipc_object_refs_t io_references;
	lck_spin_t	io_lock_data;
} __attribute__((__packed__));

/*
 * If another object type needs to participate in io_kotype()-based
 * dispatching, it must include a stub structure as the first
 * element
 */
struct ipc_object_header {
	ipc_object_bits_t io_bits;
#ifdef __LP64__
	natural_t         io_padding; /* pad to natural boundary */
#endif
};

/*
 * Legacy defines.  Should use IPC_OBJECT_NULL, etc...
 */
#define	IO_NULL			((ipc_object_t) 0)
#define	IO_DEAD			((ipc_object_t) ~0UL)
#define	IO_VALID(io)		(((io) != IO_NULL) && ((io) != IO_DEAD))

/*
 *	IPC steals the high-order bits from the kotype to use
 *	for its own purposes.  This allows IPC to record facts
 *	about ports that aren't otherwise obvious from the
 *	existing port fields.  In particular, IPC can optionally
 *	mark a port for no more senders detection.  Any change
 *	to IO_BITS_PORT_INFO must be coordinated with bitfield
 *	definitions in ipc_port.h.
 */
#define	IO_BITS_PORT_INFO	0x0000f000	/* stupid port tricks */
#define	IO_BITS_KOTYPE		0x00000fff	/* used by the object */
#define IO_BITS_OTYPE		0x7fff0000	/* determines a zone */
#define	IO_BITS_ACTIVE		0x80000000	/* is object alive? */

#define	io_active(io)		(((io)->io_bits & IO_BITS_ACTIVE) != 0)

#define	io_otype(io)		(((io)->io_bits & IO_BITS_OTYPE) >> 16)
#define	io_kotype(io)		((io)->io_bits & IO_BITS_KOTYPE)

#define	io_makebits(active, otype, kotype)	\
	(((active) ? IO_BITS_ACTIVE : 0) | ((otype) << 16) | (kotype))

/*
 * Object types: ports, port sets, kernel-loaded ports
 */
#define	IOT_PORT		0
#define IOT_PORT_SET		1
#define IOT_NUMBER		2		/* number of types used */

extern zone_t ipc_object_zones[IOT_NUMBER];

#define	io_alloc(otype)		\
		((ipc_object_t) zalloc(ipc_object_zones[(otype)]))

extern void	io_free(
			unsigned int	otype,
			ipc_object_t	object);

/*
 * Here we depend on the ipc_object being first within the kernel struct
 * (ipc_port and ipc_pset).
 */
#define io_lock_init(io) \
	lck_spin_init(&(io)->io_lock_data, &ipc_lck_grp, &ipc_lck_attr)
#define io_lock_destroy(io) \
	lck_spin_destroy(&(io)->io_lock_data, &ipc_lck_grp)
#define	io_lock(io) \
	lck_spin_lock(&(io)->io_lock_data)
#define	io_lock_try(io) \
	lck_spin_try_lock(&(io)->io_lock_data)
#define	io_unlock(io) \
	lck_spin_unlock(&(io)->io_lock_data)

#define _VOLATILE_ volatile

/* Sanity check the ref count.  If it is 0, we may be doubly zfreeing.
 * If it is larger than max int, it has been corrupted or leaked,
 * probably by being modified into an address (this is architecture
 * dependent, but it's safe to assume there cannot really be max int
 * references unless some code is leaking the io_reference without leaking
 * object). Saturate the io_reference on release kernel if it reaches
 * max int to avoid use after free.
 *
 * NOTE: The 0 test alone will not catch double zfreeing of ipc_port
 * structs, because the io_references field is the first word of the struct,
 * and zfree modifies that to point to the next free zone element.
 */
#define IO_MAX_REFERENCES						\
	(unsigned)(~0 ^ (1 << (sizeof(int)*BYTE_SIZE - 1)))

static inline void
io_reference(ipc_object_t io) {
	ipc_object_refs_t new_io_references;
	ipc_object_refs_t old_io_references;

	assert((io)->io_references > 0 &&
	    (io)->io_references < IO_MAX_REFERENCES);

	do {
		old_io_references = (io)->io_references;
		new_io_references = old_io_references + 1;
		if (old_io_references == IO_MAX_REFERENCES) {
			break;
		}
	} while (OSCompareAndSwap(old_io_references, new_io_references,
			&((io)->io_references)) == FALSE);
}


static inline void
io_release(ipc_object_t io) {
	ipc_object_refs_t new_io_references;
	ipc_object_refs_t old_io_references;

	assert((io)->io_references > 0 &&
	    (io)->io_references < IO_MAX_REFERENCES);

	do {
		old_io_references = (io)->io_references;
		new_io_references = old_io_references - 1;
		if (old_io_references == IO_MAX_REFERENCES) {
			break;
		}
	} while (OSCompareAndSwap(old_io_references, new_io_references,
			&((io)->io_references)) == FALSE);

        /* If we just removed the last reference count */
	if (1 == old_io_references) {
		/* Free the object */
		io_free(io_otype((io)), (io));
	}
}

/*   
 * Retrieve a label for use in a kernel call that takes a security
 * label as a parameter. If necessary, io_getlabel acquires internal
 * (not io_lock) locks, and io_unlocklabel releases them.
 */

struct label;
extern struct label *io_getlabel (ipc_object_t obj);
#define io_unlocklabel(obj)

/*
 * Exported interfaces
 */

/* Take a reference to an object */
extern void ipc_object_reference(
	ipc_object_t	object);

/* Release a reference to an object */
extern void ipc_object_release(
	ipc_object_t	object);

/* Look up an object in a space */
extern kern_return_t ipc_object_translate(
	ipc_space_t		space,
	mach_port_name_t	name,
	mach_port_right_t	right,
	ipc_object_t		*objectp);

/* Look up two objects in a space, locking them in the order described */
extern kern_return_t ipc_object_translate_two(
	ipc_space_t		space,
	mach_port_name_t	name1,
	mach_port_right_t	right1,
	ipc_object_t		*objectp1,
	mach_port_name_t	name2,
	mach_port_right_t	right2,
	ipc_object_t		*objectp2);

/* Allocate a dead-name entry */
extern kern_return_t
ipc_object_alloc_dead(
	ipc_space_t		space,
	mach_port_name_t 	*namep);

/*  Allocate a dead-name entry, with a specific name */
extern kern_return_t ipc_object_alloc_dead_name(
	ipc_space_t		space,
	mach_port_name_t	name);

/* Allocate an object */
extern kern_return_t ipc_object_alloc(
	ipc_space_t		space,
	ipc_object_type_t	otype,
	mach_port_type_t	type,
	mach_port_urefs_t	urefs,
	mach_port_name_t	*namep,
	ipc_object_t		*objectp);

/* Allocate an object, with a specific name */
extern kern_return_t ipc_object_alloc_name(
	ipc_space_t		space,
	ipc_object_type_t	otype,
	mach_port_type_t	type,
	mach_port_urefs_t	urefs,
	mach_port_name_t	name,
	ipc_object_t		*objectp);

/* Convert a send type name to a received type name */
extern mach_msg_type_name_t ipc_object_copyin_type(
	mach_msg_type_name_t	msgt_name);

/* Copyin a capability from a space */
extern kern_return_t ipc_object_copyin(
	ipc_space_t		space,
	mach_port_name_t	name,
	mach_msg_type_name_t	msgt_name,
	ipc_object_t		*objectp);

/* Copyin a naked capability from the kernel */
extern void ipc_object_copyin_from_kernel(
	ipc_object_t		object,
	mach_msg_type_name_t	msgt_name);

/* Destroy a naked capability */
extern void ipc_object_destroy(
	ipc_object_t		object,
	mach_msg_type_name_t	msgt_name);

/* Destroy a naked destination capability */
extern void ipc_object_destroy_dest(
	ipc_object_t		object,
	mach_msg_type_name_t	msgt_name);

/* Copyout a capability, placing it into a space */
extern kern_return_t ipc_object_copyout(
	ipc_space_t		space,
	ipc_object_t		object,
	mach_msg_type_name_t	msgt_name,
	boolean_t		overflow,
	mach_port_name_t	*namep);

/* Copyout a capability with a name, placing it into a space */
extern kern_return_t ipc_object_copyout_name(
	ipc_space_t		space,
	ipc_object_t		object,
	mach_msg_type_name_t	msgt_name,
	boolean_t		overflow,
	mach_port_name_t	name);

/* Translate/consume the destination right of a message */
extern void ipc_object_copyout_dest(
	ipc_space_t		space,
	ipc_object_t		object,
	mach_msg_type_name_t	msgt_name,
	mach_port_name_t	*namep);

/* Rename an entry in a space */
extern kern_return_t ipc_object_rename(
	ipc_space_t		space,
	mach_port_name_t	oname,
	mach_port_name_t	nname);

#endif	/* _IPC_IPC_OBJECT_H_ */