This is xnu-8019. See this file in:
/*
 * Copyright (c) 2020 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#ifndef _SYS_PROC_REQUIRE_H_
#define _SYS_PROC_REQUIRE_H_

typedef struct proc *   proc_t;

/* Used by proc_require for validation of proc zone */
__options_closed_decl(proc_require_flags_t, unsigned int, {
	PROC_REQUIRE_ALLOW_USER = 0x0, //always on, just means we allow lookup of any non kernel proc
	PROC_REQUIRE_ALLOW_NULL = 0x1,
	PROC_REQUIRE_ALLOW_KERNPROC = 0x2,
});

/* validates that 'proc' comes from within the proc zone */
void proc_require(proc_t proc, proc_require_flags_t flags);

#endif // _SYS_PROC_REQUIRE_H_