1 /*- 2 * Copyright (c) 2015 Mark R V Murray 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28 #include <sys/param.h> 29 #include <sys/systm.h> 30 #include <sys/kernel.h> 31 #include <sys/malloc.h> 32 #include <sys/random.h> 33 #include <sys/sysctl.h> 34 35 #include <dev/random/randomdev.h> 36 37 /* Set up the sysctl root node for the entropy device */ 38 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 39 "Cryptographically Secure Random Number Generator"); 40 SYSCTL_NODE(_kern_random, OID_AUTO, initial_seeding, 41 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 42 "Initial seeding control and information"); 43 44 /* 45 * N.B., this is a dangerous default, but it matches the behavior prior to 46 * r346250 (and, say, OpenBSD -- although they get some guaranteed saved 47 * entropy from the prior boot because of their KARL system, on RW media). 48 */ 49 bool random_bypass_before_seeding = true; 50 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO, 51 bypass_before_seeding, CTLFLAG_RDTUN, &random_bypass_before_seeding, 52 0, "If set non-zero, bypass the random device in requests for random " 53 "data when the random device is not yet seeded. This is considered " 54 "dangerous. Ordinarily, the random device will block requests until " 55 "it is seeded by sufficient entropy."); 56 57 /* 58 * This is a read-only diagnostic that reports the combination of the former 59 * tunable and actual bypass. It is intended for programmatic inspection by 60 * userspace administrative utilities after boot. 61 */ 62 bool read_random_bypassed_before_seeding = false; 63 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO, 64 read_random_bypassed_before_seeding, CTLFLAG_RD, 65 &read_random_bypassed_before_seeding, 0, "If non-zero, the random device " 66 "was bypassed because the 'bypass_before_seeding' knob was enabled and a " 67 "request was submitted prior to initial seeding."); 68 69 /* 70 * This is a read-only diagnostic that reports the combination of the former 71 * tunable and actual bypass for arc4random initial seeding. It is intended 72 * for programmatic inspection by userspace administrative utilities after 73 * boot. 74 */ 75 bool arc4random_bypassed_before_seeding = false; 76 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO, 77 arc4random_bypassed_before_seeding, CTLFLAG_RD, 78 &arc4random_bypassed_before_seeding, 0, "If non-zero, the random device " 79 "was bypassed when initially seeding the kernel arc4random(9), because " 80 "the 'bypass_before_seeding' knob was enabled and a request was submitted " 81 "prior to initial seeding."); 82 83 /* 84 * This knob is for users who do not want additional warnings in their logs 85 * because they intend to handle bypass by inspecting the status of the 86 * diagnostic sysctls. 87 */ 88 bool random_bypass_disable_warnings = false; 89 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO, 90 disable_bypass_warnings, CTLFLAG_RDTUN, 91 &random_bypass_disable_warnings, 0, "If non-zero, do not log a warning " 92 "if the 'bypass_before_seeding' knob is enabled and a request is " 93 "submitted prior to initial seeding."); 94 95 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers and data structures"); 96 97 #if defined(RANDOM_LOADABLE) 98 const struct random_algorithm *p_random_alg_context; 99 void (*_read_random)(void *, u_int); 100 int (*_read_random_uio)(struct uio *, bool); 101 bool (*_is_random_seeded)(void); 102 #endif /* defined(RANDOM_LOADABLE) */ 103