randomdev_soft.c revision 256281 
1/*-
2 * Copyright (c) 2000-2013 Mark R V Murray
3 * Copyright (c) 2004 Robert N. M. Watson
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer
11 *    in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28
29#if !defined(YARROW_RNG) && !defined(FORTUNA_RNG)
30#define YARROW_RNG
31#elif defined(YARROW_RNG) && defined(FORTUNA_RNG)
32#error "Must define either YARROW_RNG or FORTUNA_RNG"
33#endif
34
35#include <sys/cdefs.h>
36__FBSDID("$FreeBSD: stable/10/sys/dev/random/randomdev_soft.c 255379 2013-09-07 22:07:36Z markm $");
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/fcntl.h>
41#include <sys/kernel.h>
42#include <sys/lock.h>
43#include <sys/malloc.h>
44#include <sys/module.h>
45#include <sys/mutex.h>
46#include <sys/poll.h>
47#include <sys/random.h>
48#include <sys/selinfo.h>
49#include <sys/sysctl.h>
50#include <sys/uio.h>
51#include <sys/unistd.h>
52
53#include <machine/bus.h>
54#include <machine/cpu.h>
55
56#include <dev/random/random_adaptors.h>
57#include <dev/random/randomdev.h>
58#include <dev/random/randomdev_soft.h>
59#if defined(YARROW_RNG)
60#include <dev/random/yarrow.h>
61#endif
62#if defined(FORTUNA_RNG)
63#include <dev/random/fortuna.h>
64#endif
65
66#include "random_harvestq.h"
67
68static int randomdev_poll(int event, struct thread *td);
69static int randomdev_block(int flag);
70static void randomdev_flush_reseed(void);
71
72#if defined(YARROW_RNG)
73static struct random_adaptor random_context = {
74	.ident = "Software, Yarrow",
75	.init = randomdev_init,
76	.deinit = randomdev_deinit,
77	.block = randomdev_block,
78	.read = random_yarrow_read,
79	.write = randomdev_write,
80	.poll = randomdev_poll,
81	.reseed = randomdev_flush_reseed,
82	.seeded = 1,
83};
84#define RANDOM_MODULE_NAME	yarrow
85#define RANDOM_CSPRNG_NAME	"yarrow"
86#endif
87
88#if defined(FORTUNA_RNG)
89static struct random_adaptor random_context = {
90	.ident = "Software, Fortuna",
91	.init = randomdev_init,
92	.deinit = randomdev_deinit,
93	.block = randomdev_block,
94	.read = random_fortuna_read,
95	.write = randomdev_write,
96	.poll = randomdev_poll,
97	.reseed = randomdev_flush_reseed,
98	.seeded = 1,
99};
100#define RANDOM_MODULE_NAME	fortuna
101#define RANDOM_CSPRNG_NAME	"fortuna"
102
103#endif
104
105/* List for the dynamic sysctls */
106static struct sysctl_ctx_list random_clist;
107
108/* ARGSUSED */
109static int
110random_check_boolean(SYSCTL_HANDLER_ARGS)
111{
112	if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0)
113		*(u_int *)(oidp->oid_arg1) = 1;
114	return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
115}
116
117void
118randomdev_init(void)
119{
120	struct sysctl_oid *random_sys_o, *random_sys_harvest_o;
121
122#if defined(YARROW_RNG)
123	random_yarrow_init_alg(&random_clist);
124#endif
125#if defined(FORTUNA_RNG)
126	random_fortuna_init_alg(&random_clist);
127#endif
128
129	random_sys_o = SYSCTL_ADD_NODE(&random_clist,
130	    SYSCTL_STATIC_CHILDREN(_kern_random),
131	    OID_AUTO, "sys", CTLFLAG_RW, 0,
132	    "Entropy Device Parameters");
133
134	SYSCTL_ADD_PROC(&random_clist,
135	    SYSCTL_CHILDREN(random_sys_o),
136	    OID_AUTO, "seeded", CTLTYPE_INT | CTLFLAG_RW,
137	    &random_context.seeded, 1, random_check_boolean, "I",
138	    "Seeded State");
139
140	random_sys_harvest_o = SYSCTL_ADD_NODE(&random_clist,
141	    SYSCTL_CHILDREN(random_sys_o),
142	    OID_AUTO, "harvest", CTLFLAG_RW, 0,
143	    "Entropy Sources");
144
145	SYSCTL_ADD_PROC(&random_clist,
146	    SYSCTL_CHILDREN(random_sys_harvest_o),
147	    OID_AUTO, "ethernet", CTLTYPE_INT | CTLFLAG_RW,
148	    &harvest.ethernet, 1, random_check_boolean, "I",
149	    "Harvest NIC entropy");
150	SYSCTL_ADD_PROC(&random_clist,
151	    SYSCTL_CHILDREN(random_sys_harvest_o),
152	    OID_AUTO, "point_to_point", CTLTYPE_INT | CTLFLAG_RW,
153	    &harvest.point_to_point, 1, random_check_boolean, "I",
154	    "Harvest serial net entropy");
155	SYSCTL_ADD_PROC(&random_clist,
156	    SYSCTL_CHILDREN(random_sys_harvest_o),
157	    OID_AUTO, "interrupt", CTLTYPE_INT | CTLFLAG_RW,
158	    &harvest.interrupt, 0, random_check_boolean, "I",
159	    "Harvest IRQ entropy");
160	SYSCTL_ADD_PROC(&random_clist,
161	    SYSCTL_CHILDREN(random_sys_harvest_o),
162	    OID_AUTO, "swi", CTLTYPE_INT | CTLFLAG_RW,
163	    &harvest.swi, 0, random_check_boolean, "I",
164	    "Harvest SWI entropy");
165
166	random_harvestq_init(random_process_event);
167
168	/* Register the randomness harvesting routine */
169	randomdev_init_harvester(random_harvestq_internal,
170	    random_context.read);
171}
172
173void
174randomdev_deinit(void)
175{
176	/* Deregister the randomness harvesting routine */
177	randomdev_deinit_harvester();
178
179	/*
180	 * Command the hash/reseed thread to end and wait for it to finish
181	 */
182	random_kthread_control = -1;
183	tsleep((void *)&random_kthread_control, 0, "term", 0);
184
185#if defined(YARROW_RNG)
186	random_yarrow_deinit_alg();
187#endif
188#if defined(FORTUNA_RNG)
189	random_fortuna_deinit_alg();
190#endif
191
192	sysctl_ctx_free(&random_clist);
193}
194
195void
196randomdev_write(void *buf, int count)
197{
198	int i;
199	u_int chunk;
200
201	/*
202	 * Break the input up into HARVESTSIZE chunks. The writer has too
203	 * much control here, so "estimate" the entropy as zero.
204	 */
205	for (i = 0; i < count; i += HARVESTSIZE) {
206		chunk = HARVESTSIZE;
207		if (i + chunk >= count)
208			chunk = (u_int)(count - i);
209		random_harvestq_internal(get_cyclecount(), (char *)buf + i,
210		    chunk, 0, 0, RANDOM_WRITE);
211	}
212}
213
214void
215randomdev_unblock(void)
216{
217	if (!random_context.seeded) {
218		random_context.seeded = 1;
219		selwakeuppri(&random_context.rsel, PUSER);
220		wakeup(&random_context);
221	}
222	(void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE,
223	    ARC4_ENTR_HAVE);
224}
225
226static int
227randomdev_poll(int events, struct thread *td)
228{
229	int revents = 0;
230	mtx_lock(&random_reseed_mtx);
231
232	if (random_context.seeded)
233		revents = events & (POLLIN | POLLRDNORM);
234	else
235		selrecord(td, &random_context.rsel);
236
237	mtx_unlock(&random_reseed_mtx);
238	return revents;
239}
240
241static int
242randomdev_block(int flag)
243{
244	int error = 0;
245
246	mtx_lock(&random_reseed_mtx);
247
248	/* Blocking logic */
249	while (!random_context.seeded && !error) {
250		if (flag & O_NONBLOCK)
251			error = EWOULDBLOCK;
252		else {
253			printf("Entropy device is blocking.\n");
254			error = msleep(&random_context,
255			    &random_reseed_mtx,
256			    PUSER | PCATCH, "block", 0);
257		}
258	}
259	mtx_unlock(&random_reseed_mtx);
260
261	return error;
262}
263
264/* Helper routine to perform explicit reseeds */
265static void
266randomdev_flush_reseed(void)
267{
268	/* Command a entropy queue flush and wait for it to finish */
269	random_kthread_control = 1;
270	while (random_kthread_control)
271		pause("-", hz / 10);
272
273#if defined(YARROW_RNG)
274	random_yarrow_reseed();
275#endif
276#if defined(FORTUNA_RNG)
277	random_fortuna_reseed();
278#endif
279}
280
281static int
282randomdev_modevent(module_t mod, int type, void *unused)
283{
284
285	switch (type) {
286	case MOD_LOAD:
287		random_adaptor_register(RANDOM_CSPRNG_NAME, &random_context);
288		/*
289		 * For statically built kernels that contain both device
290		 * random and options PADLOCK_RNG/RDRAND_RNG/etc..,
291		 * this event handler will do nothing, since the random
292		 * driver-specific handlers are loaded after these HW
293		 * consumers, and hence hasn't yet registered for this event.
294		 *
295		 * In case where both the random driver and RNG's are built
296		 * as seperate modules, random.ko is loaded prior to *_rng.ko's
297		 * (by dependency). This event handler is there to delay
298		 * creation of /dev/{u,}random and attachment of this *_rng.ko.
299		 */
300		EVENTHANDLER_INVOKE(random_adaptor_attach, &random_context);
301		return (0);
302	}
303
304	return (EINVAL);
305}
306
307RANDOM_ADAPTOR_MODULE(RANDOM_MODULE_NAME, randomdev_modevent, 1);
308