xref: /xnu-8792.41.9/osfmk/mach/vm_prot.h (revision 5c2921b07a2480ab43ec66f5b9e41cb872bc554f)

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/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 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
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 * thereof, and that both notices appear in supporting documentation.
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 * 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
 *
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 *  School of Computer Science
 *  Carnegie Mellon University
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 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *	File:	mach/vm_prot.h
 *	Author:	Avadis Tevanian, Jr., Michael Wayne Young
 *
 *	Virtual memory protection definitions.
 *
 */

#ifndef _MACH_VM_PROT_H_
#define _MACH_VM_PROT_H_

/*
 *	Types defined:
 *
 *	vm_prot_t		VM protection values.
 */

typedef int             vm_prot_t;

/*
 *	Protection values, defined as bits within the vm_prot_t type
 */

#define VM_PROT_NONE    ((vm_prot_t) 0x00)

#define VM_PROT_READ    ((vm_prot_t) 0x01)      /* read permission */
#define VM_PROT_WRITE   ((vm_prot_t) 0x02)      /* write permission */
#define VM_PROT_EXECUTE ((vm_prot_t) 0x04)      /* execute permission */

/*
 *	The default protection for newly-created virtual memory
 */

#define VM_PROT_DEFAULT (VM_PROT_READ|VM_PROT_WRITE)

/*
 *	The maximum privileges possible, for parameter checking.
 */

#define VM_PROT_ALL     (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE)

/*
 *	This is an alias to VM_PROT_EXECUTE to identify callers that
 *	want to allocate an hardware assisted Read-only/read-write
 *	trusted path in userland.
 */
#define        VM_PROT_RORW_TP                 (VM_PROT_EXECUTE)

/*
 *	An invalid protection value.
 *	Used only by memory_object_lock_request to indicate no change
 *	to page locks.  Using -1 here is a bad idea because it
 *	looks like VM_PROT_ALL and then some.
 */

#define VM_PROT_NO_CHANGE_LEGACY       ((vm_prot_t) 0x08)
#define VM_PROT_NO_CHANGE              ((vm_prot_t) 0x01000000)

/*
 *      When a caller finds that he cannot obtain write permission on a
 *      mapped entry, the following flag can be used.  The entry will
 *      be made "needs copy" effectively copying the object (using COW),
 *      and write permission will be added to the maximum protections
 *      for the associated entry.
 */

#define VM_PROT_COPY            ((vm_prot_t) 0x10)


/*
 *	Another invalid protection value.
 *	Used only by memory_object_data_request upon an object
 *	which has specified a copy_call copy strategy. It is used
 *	when the kernel wants a page belonging to a copy of the
 *	object, and is only asking the object as a result of
 *	following a shadow chain. This solves the race between pages
 *	being pushed up by the memory manager and the kernel
 *	walking down the shadow chain.
 */

#define VM_PROT_WANTS_COPY      ((vm_prot_t) 0x10)

#ifdef PRIVATE
/*
 *	The caller wants this memory region treated as if it had a valid
 *	code signature.
 */

#define VM_PROT_TRUSTED         ((vm_prot_t) 0x20)
#endif /* PRIVATE */

/*
 *      Another invalid protection value.
 *	Indicates that the other protection bits are to be applied as a mask
 *	against the actual protection bits of the map entry.
 */
#define VM_PROT_IS_MASK         ((vm_prot_t) 0x40)

/*
 * Another invalid protection value to support execute-only protection.
 * VM_PROT_STRIP_READ is a special marker that tells mprotect to not
 * set VM_PROT_READ. We have to do it this way because existing code
 * expects the system to set VM_PROT_READ if VM_PROT_EXECUTE is set.
 * VM_PROT_EXECUTE_ONLY is just a convenience value to indicate that
 * the memory should be executable and explicitly not readable. It will
 * be ignored on platforms that do not support this type of protection.
 */
#define VM_PROT_STRIP_READ              ((vm_prot_t) 0x80)
#define VM_PROT_EXECUTE_ONLY    (VM_PROT_EXECUTE|VM_PROT_STRIP_READ)

#ifdef PRIVATE
/*
 * When using VM_PROT_COPY, fail instead of copying an executable mapping,
 * since that could cause code-signing violations.
 */
#define VM_PROT_COPY_FAIL_IF_EXECUTABLE ((vm_prot_t)0x100)
#endif /* PRIVATE */

#if defined(__x86_64__)
/*
 * Another invalid protection value to support specifying different
 * execute permissions for user- and supervisor- modes.  When
 * MBE is enabled in a VM, VM_PROT_EXECUTE is used to indicate
 * supervisor-mode execute permission, and VM_PROT_UEXEC specifies
 * user-mode execute permission.  Currently only used by the
 * x86 Hypervisor kext.
 */
#define VM_PROT_UEXEC                   ((vm_prot_t) 0x8)     /* User-mode Execute Permission */

#define VM_PROT_ALLEXEC                 (VM_PROT_EXECUTE | VM_PROT_UEXEC)
#else
#define VM_PROT_ALLEXEC                 (VM_PROT_EXECUTE)
#endif /* defined(__x86_64__) */


#endif  /* _MACH_VM_PROT_H_ */