2 * Copyright (c) 2015 Mark R V Murray
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
34 #include <sys/malloc.h>
35 #include <sys/random.h>
36 #include <sys/sysctl.h>
38 #include <dev/random/randomdev.h>
40 /* Set up the sysctl root node for the entropy device */
41 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
42 "Cryptographically Secure Random Number Generator");
43 SYSCTL_NODE(_kern_random, OID_AUTO, initial_seeding,
44 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
45 "Initial seeding control and information");
48 * N.B., this is a dangerous default, but it matches the behavior prior to
49 * r346250 (and, say, OpenBSD -- although they get some guaranteed saved
50 * entropy from the prior boot because of their KARL system, on RW media).
52 bool random_bypass_before_seeding = true;
53 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
54 bypass_before_seeding, CTLFLAG_RDTUN, &random_bypass_before_seeding,
55 0, "If set non-zero, bypass the random device in requests for random "
56 "data when the random device is not yet seeded. This is considered "
57 "dangerous. Ordinarily, the random device will block requests until "
58 "it is seeded by sufficient entropy.");
61 * This is a read-only diagnostic that reports the combination of the former
62 * tunable and actual bypass. It is intended for programmatic inspection by
63 * userspace administrative utilities after boot.
65 bool read_random_bypassed_before_seeding = false;
66 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
67 read_random_bypassed_before_seeding, CTLFLAG_RD,
68 &read_random_bypassed_before_seeding, 0, "If non-zero, the random device "
69 "was bypassed because the 'bypass_before_seeding' knob was enabled and a "
70 "request was submitted prior to initial seeding.");
73 * This is a read-only diagnostic that reports the combination of the former
74 * tunable and actual bypass for arc4random initial seeding. It is intended
75 * for programmatic inspection by userspace administrative utilities after
78 bool arc4random_bypassed_before_seeding = false;
79 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
80 arc4random_bypassed_before_seeding, CTLFLAG_RD,
81 &arc4random_bypassed_before_seeding, 0, "If non-zero, the random device "
82 "was bypassed when initially seeding the kernel arc4random(9), because "
83 "the 'bypass_before_seeding' knob was enabled and a request was submitted "
84 "prior to initial seeding.");
87 * This knob is for users who do not want additional warnings in their logs
88 * because they intend to handle bypass by inspecting the status of the
91 bool random_bypass_disable_warnings = false;
92 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
93 disable_bypass_warnings, CTLFLAG_RDTUN,
94 &random_bypass_disable_warnings, 0, "If non-zero, do not log a warning "
95 "if the 'bypass_before_seeding' knob is enabled and a request is "
96 "submitted prior to initial seeding.");
98 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers and data structures");
100 #if defined(RANDOM_LOADABLE)
101 const struct random_algorithm *p_random_alg_context;
102 void (*_read_random)(void *, u_int);
103 int (*_read_random_uio)(struct uio *, bool);
104 bool (*_is_random_seeded)(void);
105 #endif /* defined(RANDOM_LOADABLE) */