randomdev_soft.c revision 256381 
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 256381 2013-10-12 15:31:36Z 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};
88#define RANDOM_MODULE_NAME	yarrow
89#define RANDOM_CSPRNG_NAME	"yarrow"
90#endif
91
92#if defined(RANDOM_FORTUNA)
93static struct random_adaptor random_context = {
94	.ident = "Software, Fortuna",
95	.init = randomdev_init,
96	.deinit = randomdev_deinit,
97	.block = randomdev_block,
98	.read = random_fortuna_read,
99	.poll = randomdev_poll,
100	.reseed = randomdev_flush_reseed,
101	.seeded = 0, /* This will be excplicitly seeded at startup when secured */
102};
103#define RANDOM_MODULE_NAME	fortuna
104#define RANDOM_CSPRNG_NAME	"fortuna"
105#endif
106
107TUNABLE_INT("kern.random.sys.seeded", &random_context.seeded);
108
109/* List for the dynamic sysctls */
110static struct sysctl_ctx_list random_clist;
111
112/* ARGSUSED */
113static int
114random_check_boolean(SYSCTL_HANDLER_ARGS)
115{
116	if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0)
117		*(u_int *)(oidp->oid_arg1) = 1;
118	return (sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req));
119}
120
121void
122randomdev_init(void)
123{
124	struct sysctl_oid *random_sys_o, *random_sys_harvest_o;
125
126#if defined(RANDOM_YARROW)
127	random_yarrow_init_alg(&random_clist);
128#endif
129#if defined(RANDOM_FORTUNA)
130	random_fortuna_init_alg(&random_clist);
131#endif
132
133	random_sys_o = SYSCTL_ADD_NODE(&random_clist,
134	    SYSCTL_STATIC_CHILDREN(_kern_random),
135	    OID_AUTO, "sys", CTLFLAG_RW, 0,
136	    "Entropy Device Parameters");
137
138	SYSCTL_ADD_PROC(&random_clist,
139	    SYSCTL_CHILDREN(random_sys_o),
140	    OID_AUTO, "seeded", CTLTYPE_INT | CTLFLAG_RW,
141	    &random_context.seeded, 0, random_check_boolean, "I",
142	    "Seeded State");
143
144	random_sys_harvest_o = SYSCTL_ADD_NODE(&random_clist,
145	    SYSCTL_CHILDREN(random_sys_o),
146	    OID_AUTO, "harvest", CTLFLAG_RW, 0,
147	    "Entropy Sources");
148
149	SYSCTL_ADD_PROC(&random_clist,
150	    SYSCTL_CHILDREN(random_sys_harvest_o),
151	    OID_AUTO, "ethernet", CTLTYPE_INT | CTLFLAG_RW,
152	    &harvest.ethernet, 1, random_check_boolean, "I",
153	    "Harvest NIC entropy");
154	SYSCTL_ADD_PROC(&random_clist,
155	    SYSCTL_CHILDREN(random_sys_harvest_o),
156	    OID_AUTO, "point_to_point", CTLTYPE_INT | CTLFLAG_RW,
157	    &harvest.point_to_point, 1, random_check_boolean, "I",
158	    "Harvest serial net entropy");
159	SYSCTL_ADD_PROC(&random_clist,
160	    SYSCTL_CHILDREN(random_sys_harvest_o),
161	    OID_AUTO, "interrupt", CTLTYPE_INT | CTLFLAG_RW,
162	    &harvest.interrupt, 1, random_check_boolean, "I",
163	    "Harvest IRQ entropy");
164	SYSCTL_ADD_PROC(&random_clist,
165	    SYSCTL_CHILDREN(random_sys_harvest_o),
166	    OID_AUTO, "swi", CTLTYPE_INT | CTLFLAG_RW,
167	    &harvest.swi, 1, random_check_boolean, "I",
168	    "Harvest SWI entropy");
169
170	random_harvestq_init(random_process_event);
171
172	/* Register the randomness harvesting routine */
173	randomdev_init_harvester(random_harvestq_internal,
174	    random_context.read);
175}
176
177void
178randomdev_deinit(void)
179{
180	/* Deregister the randomness harvesting routine */
181	randomdev_deinit_harvester();
182
183	/*
184	 * Command the hash/reseed thread to end and wait for it to finish
185	 */
186	random_kthread_control = -1;
187	tsleep((void *)&random_kthread_control, 0, "term", 0);
188
189#if defined(RANDOM_YARROW)
190	random_yarrow_deinit_alg();
191#endif
192#if defined(RANDOM_FORTUNA)
193	random_fortuna_deinit_alg();
194#endif
195
196	sysctl_ctx_free(&random_clist);
197}
198
199void
200randomdev_unblock(void)
201{
202	if (!random_context.seeded) {
203		selwakeuppri(&random_context.rsel, PUSER);
204		wakeup(&random_context);
205                printf("random: unblocking device.\n");
206		random_context.seeded = 1;
207	}
208	/* Do arc4random(9) a favour while we are about it. */
209	(void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE,
210	    ARC4_ENTR_HAVE);
211}
212
213static int
214randomdev_poll(int events, struct thread *td)
215{
216	int revents = 0;
217
218	mtx_lock(&random_reseed_mtx);
219
220	if (random_context.seeded)
221		revents = events & (POLLIN | POLLRDNORM);
222	else
223		selrecord(td, &random_context.rsel);
224
225	mtx_unlock(&random_reseed_mtx);
226	return (revents);
227}
228
229static int
230randomdev_block(int flag)
231{
232	int error = 0;
233
234	mtx_lock(&random_reseed_mtx);
235
236	/* Blocking logic */
237	while (!random_context.seeded && !error) {
238		if (flag & O_NONBLOCK)
239			error = EWOULDBLOCK;
240		else {
241			printf("random: blocking on read.\n");
242			error = msleep(&random_context,
243			    &random_reseed_mtx,
244			    PUSER | PCATCH, "block", 0);
245		}
246	}
247	mtx_unlock(&random_reseed_mtx);
248
249	return (error);
250}
251
252/* Helper routine to perform explicit reseeds */
253static void
254randomdev_flush_reseed(void)
255{
256	/* Command a entropy queue flush and wait for it to finish */
257	random_kthread_control = 1;
258	while (random_kthread_control)
259		pause("-", hz / 10);
260
261#if defined(RANDOM_YARROW)
262	/* This ultimately calls randomdev_unblock() */
263	random_yarrow_reseed();
264#endif
265#if defined(RANDOM_FORTUNA)
266	/* This ultimately calls randomdev_unblock() */
267	random_fortuna_reseed();
268#endif
269}
270
271static int
272randomdev_modevent(module_t mod __unused, int type, void *unused __unused)
273{
274
275	switch (type) {
276	case MOD_LOAD:
277		random_adaptor_register(RANDOM_CSPRNG_NAME, &random_context);
278		/*
279		 * For statically built kernels that contain both device
280		 * random and options PADLOCK_RNG/RDRAND_RNG/etc..,
281		 * this event handler will do nothing, since the random
282		 * driver-specific handlers are loaded after these HW
283		 * consumers, and hence hasn't yet registered for this event.
284		 *
285		 * In case where both the random driver and RNG's are built
286		 * as seperate modules, random.ko is loaded prior to *_rng.ko's
287		 * (by dependency). This event handler is there to delay
288		 * creation of /dev/{u,}random and attachment of this *_rng.ko.
289		 */
290		EVENTHANDLER_INVOKE(random_adaptor_attach, &random_context);
291		return (0);
292	}
293
294	return (EINVAL);
295}
296
297RANDOM_ADAPTOR_MODULE(RANDOM_MODULE_NAME, randomdev_modevent, 1);
298