65408ffc2e7b90c9eac8362cbb6dea71d7549e4c
[dragonfly.git] / sys / dev / crypto / rdrand / rdrand.c
1 /*
2  * Copyright (c) 2012 Alex Hornung <alex@alexhornung.com>.
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  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in
13  *    the documentation and/or other materials provided with the
14  *    distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
19  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
20  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
22  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
24  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 #include <sys/kobj.h>
33 #include <sys/libkern.h>
34 #include <sys/module.h>
35 #include <sys/bus.h>
36 #include <sys/random.h>
37 #include <sys/sysctl.h>
38
39 #include <machine/specialreg.h>
40
41 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16))
42 #define RDRAND_SIZE     512
43
44 static int rdrand_debug;
45 SYSCTL_INT(_debug, OID_AUTO, rdrand, CTLFLAG_RW, &rdrand_debug, 0,
46            "Enable rdrand debugging");
47
48 struct rdrand_softc {
49         struct callout  sc_rng_co;
50         int32_t         sc_rng_ticks;
51 };
52
53
54 static void rdrand_rng_harvest(void *);
55 int rdrand_rng(uint8_t *out, long limit);
56
57
58 static void
59 rdrand_identify(driver_t *drv, device_t parent)
60 {
61
62         /* NB: order 10 is so we get attached after h/w devices */
63         if (device_find_child(parent, "rdrand", -1) == NULL &&
64             BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0)
65                 panic("rdrand: could not attach");
66 }
67
68
69 static int
70 rdrand_probe(device_t dev)
71 {
72
73         if ((cpu_feature2 & CPUID2_RDRAND) == 0) {
74                 device_printf(dev, "No RdRand support.\n");
75                 return (EINVAL);
76         }
77
78         device_set_desc(dev, "RdRand RNG");
79         return 0;
80 }
81
82
83 static int
84 rdrand_attach(device_t dev)
85 {
86         struct rdrand_softc *sc;
87
88         sc = device_get_softc(dev);
89
90         if (hz > 10)
91                 sc->sc_rng_ticks = hz / 10;
92         else
93                 sc->sc_rng_ticks = 1;
94
95         callout_init_mp(&sc->sc_rng_co);
96         callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
97                       rdrand_rng_harvest, sc);
98
99         return 0;
100 }
101
102
103 static int
104 rdrand_detach(device_t dev)
105 {
106         struct rdrand_softc *sc;
107
108         sc = device_get_softc(dev);
109
110         callout_stop_sync(&sc->sc_rng_co);
111
112         return (0);
113 }
114
115
116 static void
117 rdrand_rng_harvest(void *arg)
118 {
119         struct rdrand_softc *sc = arg;
120         uint8_t randomness[RDRAND_SIZE + 32];
121         uint8_t *arandomness; /* randomness aligned */
122         int cnt;
123
124         arandomness = RDRAND_ALIGN(randomness);
125
126         cnt = rdrand_rng(arandomness, RDRAND_SIZE);
127         if (cnt > 0 && cnt < sizeof(randomness)) {
128                 add_buffer_randomness_src(arandomness, cnt, RAND_SRC_RDRAND);
129
130                 if (rdrand_debug) {
131                         kprintf("rdrand(%d): %02x %02x %02x %02x...\n",
132                                 cnt,
133                                 arandomness[0],
134                                 arandomness[1],
135                                 arandomness[2],
136                                 arandomness[3]);
137                 }
138         }
139
140         callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
141                       rdrand_rng_harvest, sc);
142 }
143
144
145 static device_method_t rdrand_methods[] = {
146         DEVMETHOD(device_identify, rdrand_identify),
147         DEVMETHOD(device_probe, rdrand_probe),
148         DEVMETHOD(device_attach, rdrand_attach),
149         DEVMETHOD(device_detach, rdrand_detach),
150
151         DEVMETHOD_END
152 };
153
154
155 static driver_t rdrand_driver = {
156         "rdrand",
157         rdrand_methods,
158         sizeof(struct rdrand_softc),
159 };
160
161 static devclass_t rdrand_devclass;
162
163 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL);
164 MODULE_VERSION(rdrand, 1);
165 MODULE_DEPEND(rdrand, crypto, 1, 1, 1);