88 lines
3.6 KiB
C
88 lines
3.6 KiB
C
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/*
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* Copyright (c) 2002-2022 Apple Inc. All rights reserved.
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*
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* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
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*
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* This file contains Original Code and/or Modifications of Original Code
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* as defined in and that are subject to the Apple Public Source License
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* Version 2.0 (the 'License'). You may not use this file except in
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* compliance with the License. The rights granted to you under the License
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* may not be used to create, or enable the creation or redistribution of,
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* unlawful or unlicensed copies of an Apple operating system, or to
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* circumvent, violate, or enable the circumvention or violation of, any
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* terms of an Apple operating system software license agreement.
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*
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* Please obtain a copy of the License at
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* http://www.opensource.apple.com/apsl/ and read it before using this file.
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*
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* The Original Code and all software distributed under the License are
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* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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* Please see the License for the specific language governing rights and
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* limitations under the License.
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*
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* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
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*/
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/*-
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* Copyright (c) 2008 Michael J. Silbersack.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/kernel.h>
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#include <netinet/ip_var.h>
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#include <sys/random.h>
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#include <dev/random/randomdev.h>
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uint16_t
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ip_randomid(uint64_t salt)
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{
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uint16_t new_id;
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/*
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* Mostly the salt value is heap or stack pointer value.
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* To avoid any chance of leaking address apply macro that
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* adds per-boot random number to it.
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*/
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uint64_t salt_tmp = VM_KERNEL_ADDRPERM(salt);
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/*
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* When the passed salt values are addresses, it is possible some bits
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* to not change at all, for example some higher order bits may not change
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* and some lower order bits may be all 0s given particular alignment and object
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* sizes.
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* Therefore we compute a XOR'd 16bit value by considering all the bits
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* of the salt to increase the likelihood of it being different.
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*/
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uint16_t new_id_salt = (uint16_t)(((salt_tmp >> 48) ^ (salt_tmp >> 32) ^
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(salt_tmp >> 16) ^ salt_tmp) & 0xFF);
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/* Avoid returning IP ID value of 0 */
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do {
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read_random(&new_id, sizeof(new_id));
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} while (new_id == new_id_salt);
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return new_id ^ new_id_salt;
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}
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