1 | /* |
2 | * Copyright (c) 2002-2022 Apple Inc. All rights reserved. |
3 | * |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
5 | * |
6 | * This file contains Original Code and/or Modifications of Original Code |
7 | * as defined in and that are subject to the Apple Public Source License |
8 | * Version 2.0 (the 'License'). You may not use this file except in |
9 | * compliance with the License. The rights granted to you under the License |
10 | * may not be used to create, or enable the creation or redistribution of, |
11 | * unlawful or unlicensed copies of an Apple operating system, or to |
12 | * circumvent, violate, or enable the circumvention or violation of, any |
13 | * terms of an Apple operating system software license agreement. |
14 | * |
15 | * Please obtain a copy of the License at |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. |
17 | * |
18 | * The Original Code and all software distributed under the License are |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
23 | * Please see the License for the specific language governing rights and |
24 | * limitations under the License. |
25 | * |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
27 | */ |
28 | |
29 | /*- |
30 | * Copyright (c) 2008 Michael J. Silbersack. |
31 | * All rights reserved. |
32 | * |
33 | * Redistribution and use in source and binary forms, with or without |
34 | * modification, are permitted provided that the following conditions |
35 | * are met: |
36 | * 1. Redistributions of source code must retain the above copyright |
37 | * notice unmodified, this list of conditions, and the following |
38 | * disclaimer. |
39 | * 2. Redistributions in binary form must reproduce the above copyright |
40 | * notice, this list of conditions and the following disclaimer in the |
41 | * documentation and/or other materials provided with the distribution. |
42 | * |
43 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
44 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
45 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
46 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
47 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
48 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
49 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
50 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
51 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
52 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
53 | */ |
54 | #include <sys/kernel.h> |
55 | #include <netinet/ip_var.h> |
56 | #include <sys/random.h> |
57 | #include <dev/random/randomdev.h> |
58 | |
59 | uint16_t |
60 | ip_randomid(uint64_t salt) |
61 | { |
62 | uint16_t new_id; |
63 | /* |
64 | * Mostly the salt value is heap or stack pointer value. |
65 | * To avoid any chance of leaking address apply macro that |
66 | * adds per-boot random number to it. |
67 | */ |
68 | uint64_t salt_tmp = VM_KERNEL_ADDRPERM(salt); |
69 | |
70 | /* |
71 | * When the passed salt values are addresses, it is possible some bits |
72 | * to not change at all, for example some higher order bits may not change |
73 | * and some lower order bits may be all 0s given particular alignment and object |
74 | * sizes. |
75 | * Therefore we compute a XOR'd 16bit value by considering all the bits |
76 | * of the salt to increase the likelihood of it being different. |
77 | */ |
78 | uint16_t new_id_salt = (uint16_t)(((salt_tmp >> 48) ^ (salt_tmp >> 32) ^ |
79 | (salt_tmp >> 16) ^ salt_tmp) & 0xFF); |
80 | |
81 | /* Avoid returning IP ID value of 0 */ |
82 | do { |
83 | read_random(buffer: &new_id, numBytes: sizeof(new_id)); |
84 | } while (new_id == new_id_salt); |
85 | |
86 | return new_id ^ new_id_salt; |
87 | } |
88 | |