1*43a90889SApple OSS Distributions /*
2*43a90889SApple OSS Distributions * Copyright (c) 2002-2024 Apple Inc. All rights reserved.
3*43a90889SApple OSS Distributions *
4*43a90889SApple OSS Distributions * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5*43a90889SApple OSS Distributions *
6*43a90889SApple OSS Distributions * This file contains Original Code and/or Modifications of Original Code
7*43a90889SApple OSS Distributions * as defined in and that are subject to the Apple Public Source License
8*43a90889SApple OSS Distributions * Version 2.0 (the 'License'). You may not use this file except in
9*43a90889SApple OSS Distributions * compliance with the License. The rights granted to you under the License
10*43a90889SApple OSS Distributions * may not be used to create, or enable the creation or redistribution of,
11*43a90889SApple OSS Distributions * unlawful or unlicensed copies of an Apple operating system, or to
12*43a90889SApple OSS Distributions * circumvent, violate, or enable the circumvention or violation of, any
13*43a90889SApple OSS Distributions * terms of an Apple operating system software license agreement.
14*43a90889SApple OSS Distributions *
15*43a90889SApple OSS Distributions * Please obtain a copy of the License at
16*43a90889SApple OSS Distributions * http://www.opensource.apple.com/apsl/ and read it before using this file.
17*43a90889SApple OSS Distributions *
18*43a90889SApple OSS Distributions * The Original Code and all software distributed under the License are
19*43a90889SApple OSS Distributions * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20*43a90889SApple OSS Distributions * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21*43a90889SApple OSS Distributions * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22*43a90889SApple OSS Distributions * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23*43a90889SApple OSS Distributions * Please see the License for the specific language governing rights and
24*43a90889SApple OSS Distributions * limitations under the License.
25*43a90889SApple OSS Distributions *
26*43a90889SApple OSS Distributions * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27*43a90889SApple OSS Distributions */
28*43a90889SApple OSS Distributions
29*43a90889SApple OSS Distributions /*-
30*43a90889SApple OSS Distributions * Copyright (c) 2008 Michael J. Silbersack.
31*43a90889SApple OSS Distributions * All rights reserved.
32*43a90889SApple OSS Distributions *
33*43a90889SApple OSS Distributions * Redistribution and use in source and binary forms, with or without
34*43a90889SApple OSS Distributions * modification, are permitted provided that the following conditions
35*43a90889SApple OSS Distributions * are met:
36*43a90889SApple OSS Distributions * 1. Redistributions of source code must retain the above copyright
37*43a90889SApple OSS Distributions * notice unmodified, this list of conditions, and the following
38*43a90889SApple OSS Distributions * disclaimer.
39*43a90889SApple OSS Distributions * 2. Redistributions in binary form must reproduce the above copyright
40*43a90889SApple OSS Distributions * notice, this list of conditions and the following disclaimer in the
41*43a90889SApple OSS Distributions * documentation and/or other materials provided with the distribution.
42*43a90889SApple OSS Distributions *
43*43a90889SApple OSS Distributions * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
44*43a90889SApple OSS Distributions * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
45*43a90889SApple OSS Distributions * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
46*43a90889SApple OSS Distributions * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
47*43a90889SApple OSS Distributions * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
48*43a90889SApple OSS Distributions * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
49*43a90889SApple OSS Distributions * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
50*43a90889SApple OSS Distributions * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
51*43a90889SApple OSS Distributions * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
52*43a90889SApple OSS Distributions * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
53*43a90889SApple OSS Distributions */
54*43a90889SApple OSS Distributions #include <sys/kernel.h>
55*43a90889SApple OSS Distributions #include <netinet/ip_var.h>
56*43a90889SApple OSS Distributions #include <sys/random.h>
57*43a90889SApple OSS Distributions #include <dev/random/randomdev.h>
58*43a90889SApple OSS Distributions
59*43a90889SApple OSS Distributions uint16_t
ip_randomid(uint64_t salt)60*43a90889SApple OSS Distributions ip_randomid(uint64_t salt)
61*43a90889SApple OSS Distributions {
62*43a90889SApple OSS Distributions uint16_t new_id;
63*43a90889SApple OSS Distributions /*
64*43a90889SApple OSS Distributions * Mostly the salt value is heap or stack pointer value.
65*43a90889SApple OSS Distributions * To avoid any chance of leaking address apply macro that
66*43a90889SApple OSS Distributions * adds per-boot random number to it.
67*43a90889SApple OSS Distributions */
68*43a90889SApple OSS Distributions uint64_t salt_tmp = VM_KERNEL_ADDRPERM(salt);
69*43a90889SApple OSS Distributions
70*43a90889SApple OSS Distributions /*
71*43a90889SApple OSS Distributions * When the passed salt values are addresses, it is possible some bits
72*43a90889SApple OSS Distributions * to not change at all, for example some higher order bits may not change
73*43a90889SApple OSS Distributions * and some lower order bits may be all 0s given particular alignment and object
74*43a90889SApple OSS Distributions * sizes.
75*43a90889SApple OSS Distributions * Therefore we compute a XOR'd 16bit value by considering all the bits
76*43a90889SApple OSS Distributions * of the salt to increase the likelihood of it being different.
77*43a90889SApple OSS Distributions */
78*43a90889SApple OSS Distributions uint16_t new_id_salt = (uint16_t)(((salt_tmp >> 48) ^ (salt_tmp >> 32) ^
79*43a90889SApple OSS Distributions (salt_tmp >> 16) ^ salt_tmp) & 0xFF);
80*43a90889SApple OSS Distributions
81*43a90889SApple OSS Distributions /* Avoid returning IP ID value of 0 */
82*43a90889SApple OSS Distributions do {
83*43a90889SApple OSS Distributions read_random(&new_id, sizeof(new_id));
84*43a90889SApple OSS Distributions } while (new_id == new_id_salt);
85*43a90889SApple OSS Distributions
86*43a90889SApple OSS Distributions return new_id ^ new_id_salt;
87*43a90889SApple OSS Distributions }
88