randomdev_soft.c revision 256414 
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#include "opt_random.h"
30
31#if !defined(RANDOM_YARROW) && !defined(RANDOM_FORTUNA)
32#define RANDOM_YARROW
33#elif defined(RANDOM_YARROW) && defined(RANDOM_FORTUNA)
34#error "Must define either RANDOM_YARROW or RANDOM_FORTUNA"
35#endif
36#if defined(RANDOM_FORTUNA)
37#error "Fortuna is not yet implemented"
38#endif
39
40#include <sys/cdefs.h>
41__FBSDID("$FreeBSD: stable/10/sys/dev/random/randomdev_soft.c 256414 2013-10-13 00:13:57Z markm $");
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/fcntl.h>
46#include <sys/kernel.h>
47#include <sys/lock.h>
48#include <sys/malloc.h>
49#include <sys/module.h>
50#include <sys/mutex.h>
51#include <sys/poll.h>
52#include <sys/random.h>
53#include <sys/selinfo.h>
54#include <sys/sysctl.h>
55#include <sys/uio.h>
56#include <sys/unistd.h>
57
58#include <machine/bus.h>
59#include <machine/cpu.h>
60
61#include <dev/random/randomdev.h>
62#include <dev/random/randomdev_soft.h>
63#include <dev/random/random_harvestq.h>
64#include <dev/random/random_adaptors.h>
65#if defined(RANDOM_YARROW)
66#include <dev/random/yarrow.h>
67#endif
68#if defined(RANDOM_FORTUNA)
69#include <dev/random/fortuna.h>
70#endif
71
72
73static int randomdev_poll(int event, struct thread *td);
74static int randomdev_block(int flag);
75static void randomdev_flush_reseed(void);
76
77#if defined(RANDOM_YARROW)
78static struct random_adaptor random_context = {
79	.ident = "Software, Yarrow",
80	.init = randomdev_init,
81	.deinit = randomdev_deinit,
82	.block = randomdev_block,
83	.read = random_yarrow_read,
84	.poll = randomdev_poll,
85	.reseed = randomdev_flush_reseed,
86	.seeded = 0, /* This will be seeded during entropy processing */
87	.priority = 90, /* High priority, so top of the list. Fortuna may still win. */
88};
89#define RANDOM_MODULE_NAME	yarrow
90#define RANDOM_CSPRNG_NAME	"yarrow"
91#endif
92
93#if defined(RANDOM_FORTUNA)
94static struct random_adaptor random_context = {
95	.ident = "Software, Fortuna",
96	.init = randomdev_init,
97	.deinit = randomdev_deinit,
98	.block = randomdev_block,
99	.read = random_fortuna_read,
100	.poll = randomdev_poll,
101	.reseed = randomdev_flush_reseed,
102	.seeded = 0, /* This will be excplicitly seeded at startup when secured */
103	.priority = 100, /* High priority, so top of the list. Beat Yarrow. */
104};
105#define RANDOM_MODULE_NAME	fortuna
106#define RANDOM_CSPRNG_NAME	"fortuna"
107#endif
108
109TUNABLE_INT("kern.random.sys.seeded", &random_context.seeded);
110
111/* List for the dynamic sysctls */
112static struct sysctl_ctx_list random_clist;
113
114/* ARGSUSED */
115static int
116random_check_boolean(SYSCTL_HANDLER_ARGS)
117{
118	if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0)
119		*(u_int *)(oidp->oid_arg1) = 1;
120	return (sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req));
121}
122
123void
124randomdev_init(void)
125{
126	struct sysctl_oid *random_sys_o, *random_sys_harvest_o;
127
128#if defined(RANDOM_YARROW)
129	random_yarrow_init_alg(&random_clist);
130#endif
131#if defined(RANDOM_FORTUNA)
132	random_fortuna_init_alg(&random_clist);
133#endif
134
135	random_sys_o = SYSCTL_ADD_NODE(&random_clist,
136	    SYSCTL_STATIC_CHILDREN(_kern_random),
137	    OID_AUTO, "sys", CTLFLAG_RW, 0,
138	    "Entropy Device Parameters");
139
140	SYSCTL_ADD_PROC(&random_clist,
141	    SYSCTL_CHILDREN(random_sys_o),
142	    OID_AUTO, "seeded", CTLTYPE_INT | CTLFLAG_RW,
143	    &random_context.seeded, 0, random_check_boolean, "I",
144	    "Seeded State");
145
146	random_sys_harvest_o = SYSCTL_ADD_NODE(&random_clist,
147	    SYSCTL_CHILDREN(random_sys_o),
148	    OID_AUTO, "harvest", CTLFLAG_RW, 0,
149	    "Entropy Sources");
150
151	SYSCTL_ADD_PROC(&random_clist,
152	    SYSCTL_CHILDREN(random_sys_harvest_o),
153	    OID_AUTO, "ethernet", CTLTYPE_INT | CTLFLAG_RW,
154	    &harvest.ethernet, 1, random_check_boolean, "I",
155	    "Harvest NIC entropy");
156	SYSCTL_ADD_PROC(&random_clist,
157	    SYSCTL_CHILDREN(random_sys_harvest_o),
158	    OID_AUTO, "point_to_point", CTLTYPE_INT | CTLFLAG_RW,
159	    &harvest.point_to_point, 1, random_check_boolean, "I",
160	    "Harvest serial net entropy");
161	SYSCTL_ADD_PROC(&random_clist,
162	    SYSCTL_CHILDREN(random_sys_harvest_o),
163	    OID_AUTO, "interrupt", CTLTYPE_INT | CTLFLAG_RW,
164	    &harvest.interrupt, 1, random_check_boolean, "I",
165	    "Harvest IRQ entropy");
166	SYSCTL_ADD_PROC(&random_clist,
167	    SYSCTL_CHILDREN(random_sys_harvest_o),
168	    OID_AUTO, "swi", CTLTYPE_INT | CTLFLAG_RW,
169	    &harvest.swi, 1, random_check_boolean, "I",
170	    "Harvest SWI entropy");
171
172	random_harvestq_init(random_process_event);
173
174	/* Register the randomness harvesting routine */
175	randomdev_init_harvester(random_harvestq_internal,
176	    random_context.read);
177}
178
179void
180randomdev_deinit(void)
181{
182	/* Deregister the randomness harvesting routine */
183	randomdev_deinit_harvester();
184
185	/*
186	 * Command the hash/reseed thread to end and wait for it to finish
187	 */
188	random_kthread_control = -1;
189	tsleep((void *)&random_kthread_control, 0, "term", 0);
190
191#if defined(RANDOM_YARROW)
192	random_yarrow_deinit_alg();
193#endif
194#if defined(RANDOM_FORTUNA)
195	random_fortuna_deinit_alg();
196#endif
197
198	sysctl_ctx_free(&random_clist);
199}
200
201void
202randomdev_unblock(void)
203{
204	if (!random_context.seeded) {
205		selwakeuppri(&random_context.rsel, PUSER);
206		wakeup(&random_context);
207                printf("random: unblocking device.\n");
208		random_context.seeded = 1;
209	}
210	/* Do arc4random(9) a favour while we are about it. */
211	(void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE,
212	    ARC4_ENTR_HAVE);
213}
214
215static int
216randomdev_poll(int events, struct thread *td)
217{
218	int revents = 0;
219
220	mtx_lock(&random_reseed_mtx);
221
222	if (random_context.seeded)
223		revents = events & (POLLIN | POLLRDNORM);
224	else
225		selrecord(td, &random_context.rsel);
226
227	mtx_unlock(&random_reseed_mtx);
228	return (revents);
229}
230
231static int
232randomdev_block(int flag)
233{
234	int error = 0;
235
236	mtx_lock(&random_reseed_mtx);
237
238	/* Blocking logic */
239	while (!random_context.seeded && !error) {
240		if (flag & O_NONBLOCK)
241			error = EWOULDBLOCK;
242		else {
243			printf("random: blocking on read.\n");
244			error = msleep(&random_context,
245			    &random_reseed_mtx,
246			    PUSER | PCATCH, "block", 0);
247		}
248	}
249	mtx_unlock(&random_reseed_mtx);
250
251	return (error);
252}
253
254/* Helper routine to perform explicit reseeds */
255static void
256randomdev_flush_reseed(void)
257{
258	/* Command a entropy queue flush and wait for it to finish */
259	random_kthread_control = 1;
260	while (random_kthread_control)
261		pause("-", hz / 10);
262
263#if defined(RANDOM_YARROW)
264	/* This ultimately calls randomdev_unblock() */
265	random_yarrow_reseed();
266#endif
267#if defined(RANDOM_FORTUNA)
268	/* This ultimately calls randomdev_unblock() */
269	random_fortuna_reseed();
270#endif
271}
272
273static int
274randomdev_modevent(module_t mod __unused, int type, void *unused __unused)
275{
276
277	switch (type) {
278	case MOD_LOAD:
279		random_adaptor_register(RANDOM_CSPRNG_NAME, &random_context);
280		/*
281		 * For statically built kernels that contain both device
282		 * random and options PADLOCK_RNG/RDRAND_RNG/etc..,
283		 * this event handler will do nothing, since the random
284		 * driver-specific handlers are loaded after these HW
285		 * consumers, and hence hasn't yet registered for this event.
286		 *
287		 * In case where both the random driver and RNG's are built
288		 * as seperate modules, random.ko is loaded prior to *_rng.ko's
289		 * (by dependency). This event handler is there to delay
290		 * creation of /dev/{u,}random and attachment of this *_rng.ko.
291		 */
292		EVENTHANDLER_INVOKE(random_adaptor_attach, &random_context);
293		return (0);
294	}
295
296	return (EINVAL);
297}
298
299RANDOM_ADAPTOR_MODULE(RANDOM_MODULE_NAME, randomdev_modevent, 1);
300