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 #if defined(RANDOM_LOADABLE)
43 #include <dev/random/randomdev.h>
45 /* Set up the sysctl root node for the entropy device */
46 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 0,
47 "Cryptographically Secure Random Number Generator");
48 SYSCTL_NODE(_kern_random, OID_AUTO, initial_seeding, CTLFLAG_RW, 0,
49 "Initial seeding control and information");
52 * N.B., this is a dangerous default, but it matches the behavior prior to
53 * r346250 (and, say, OpenBSD -- although they get some guaranteed saved
54 * entropy from the prior boot because of their KARL system, on RW media).
56 bool random_bypass_before_seeding = true;
57 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
58 bypass_before_seeding, CTLFLAG_RDTUN, &random_bypass_before_seeding,
59 0, "If set non-zero, bypass the random device in requests for random "
60 "data when the random device is not yet seeded. This is considered "
61 "dangerous. Ordinarily, the random device will block requests until "
62 "it is seeded by sufficient entropy.");
65 * This is a read-only diagnostic that reports the combination of the former
66 * tunable and actual bypass. It is intended for programmatic inspection by
67 * userspace administrative utilities after boot.
69 bool read_random_bypassed_before_seeding = false;
70 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
71 read_random_bypassed_before_seeding, CTLFLAG_RD,
72 &read_random_bypassed_before_seeding, 0, "If non-zero, the random device "
73 "was bypassed because the 'bypass_before_seeding' knob was enabled and a "
74 "request was submitted prior to initial seeding.");
77 * This is a read-only diagnostic that reports the combination of the former
78 * tunable and actual bypass for arc4random initial seeding. It is intended
79 * for programmatic inspection by userspace administrative utilities after
82 bool arc4random_bypassed_before_seeding = false;
83 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
84 arc4random_bypassed_before_seeding, CTLFLAG_RD,
85 &arc4random_bypassed_before_seeding, 0, "If non-zero, the random device "
86 "was bypassed when initially seeding the kernel arc4random(9), because "
87 "the 'bypass_before_seeding' knob was enabled and a request was submitted "
88 "prior to initial seeding.");
91 * This knob is for users who do not want additional warnings in their logs
92 * because they intend to handle bypass by inspecting the status of the
95 bool random_bypass_disable_warnings = false;
96 SYSCTL_BOOL(_kern_random_initial_seeding, OID_AUTO,
97 disable_bypass_warnings, CTLFLAG_RDTUN,
98 &random_bypass_disable_warnings, 0, "If non-zero, do not log a warning "
99 "if the 'bypass_before_seeding' knob is enabled and a request is "
100 "submitted prior to initial seeding.");
102 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers and data structures");
104 struct sources_head source_list = LIST_HEAD_INITIALIZER(source_list);
106 #if defined(RANDOM_LOADABLE)
107 struct random_algorithm *p_random_alg_context = NULL;
108 #else /* !defined(RANDOM_LOADABLE) */
109 struct random_algorithm *p_random_alg_context = &random_alg_context;
110 #endif /* defined(RANDOM_LOADABLE) */
112 #if defined(RANDOM_LOADABLE)
115 null_read_random(void *dummy __unused, u_int dummy2 __unused)
117 panic("%s: no random module is loaded", __func__);
121 null_is_random_seeded(void)
126 struct random_readers {
127 int (*read_random_uio)(struct uio *, bool);
128 void (*read_random)(void *, u_int);
129 bool (*is_random_seeded)(void);
130 } random_reader_context = {
131 (int (*)(struct uio *, bool))nullop,
133 null_is_random_seeded,
136 struct sx randomdev_config_lock;
139 random_infra_sysinit(void *dummy __unused)
142 RANDOM_CONFIG_INIT_LOCK();
144 SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_FIRST, random_infra_sysinit, NULL);
147 random_infra_init(int (*p_random_read_uio)(struct uio *, bool),
148 void (*p_random_read)(void *, u_int),
149 bool (*p_is_random_seeded)(void))
152 RANDOM_CONFIG_X_LOCK();
153 random_reader_context.read_random_uio = p_random_read_uio;
154 random_reader_context.read_random = p_random_read;
155 random_reader_context.is_random_seeded = p_is_random_seeded;
156 RANDOM_CONFIG_X_UNLOCK();
160 random_infra_uninit(void)
163 RANDOM_CONFIG_X_LOCK();
164 random_reader_context.read_random_uio = (int (*)(struct uio *, bool))nullop;
165 random_reader_context.read_random = null_read_random;
166 random_reader_context.is_random_seeded = null_is_random_seeded;
167 RANDOM_CONFIG_X_UNLOCK();
171 random_infra_sysuninit(void *dummy __unused)
174 RANDOM_CONFIG_DEINIT_LOCK();
176 SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_FIRST, random_infra_sysuninit, NULL);
179 read_random_uio(struct uio *uio, bool nonblock)
183 RANDOM_CONFIG_S_LOCK();
184 retval = random_reader_context.read_random_uio(uio, nonblock);
185 RANDOM_CONFIG_S_UNLOCK();
190 read_random(void *buf, u_int len)
193 RANDOM_CONFIG_S_LOCK();
194 random_reader_context.read_random(buf, len);
195 RANDOM_CONFIG_S_UNLOCK();
199 is_random_seeded(void)
203 RANDOM_CONFIG_S_LOCK();
204 result = random_reader_context.is_random_seeded();
205 RANDOM_CONFIG_S_UNLOCK();
210 #endif /* defined(RANDOM_LOADABLE) */