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1) example (partially humorous random_adaptor, that I call "EXAMPLE")

Browse Source 
* It's not meant to be used in a real system, it's there to show how
   the basics of how to create interfaces for random_adaptors. Perhaps
   it should belong in a manual page

2) Move probe.c's functionality in to random_adaptors.c
 * rename random_ident_hardware() to random_adaptor_choose()

3) Introduce a new way to choose (or select) random_adaptors via tunable
"rngs_want" It's a list of comma separated names of adaptors, ordered
by preferences. I.e.:
rngs_want="yarrow,rdrand"

Such setting would cause yarrow to be preferred to rdrand. If neither of
them are available (or registered), then system will default to
something reasonable (currently yarrow). If yarrow is not present, then
we fall back to the adaptor that's first on the list of registered
adaptors.

4) Introduce a way where RNGs can play a role of entropy source. This is
mostly useful for HW rngs.

The way I envision this is that every HW RNG will use this
functionality by default. Functionality to disable this is also present.
I have an example of how to use this in random_adaptor_example.c (see
modload event, and init function)

5) fix kern.random.adaptors from
kern.random.adaptors: yarrowpanicblock
to
kern.random.adaptors: yarrow,panic,block

6) add kern.random.active_adaptor to indicate currently selected
adaptor:
root@freebsd04:~ # sysctl kern.random.active_adaptor
kern.random.active_adaptor: yarrow

Submitted by:	Arthur Mesh <arthurmesh@gmail.com>
This commit is contained in:
markm 2013-08-24 13:54:56 +00:00
parent 6228164aca
commit c7ceb49e15
11 changed files with 472 additions and 75 deletions
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2
share/examples/kld/Makefile
View File

@ -67,6 +67,6 @@
# $FreeBSD$
#
SUBDIR= cdev dyn_sysctl firmware khelp syscall
SUBDIR= cdev dyn_sysctl firmware khelp random_adaptor syscall
.include <bsd.subdir.mk>

6
share/examples/kld/random_adaptor/Makefile Normal file
View File

@ -0,0 +1,6 @@
# $FreeBSD$
KMOD= random_adaptor_example
SRCS= ${KMOD}.c
.include <bsd.kmod.mk>

112
share/examples/kld/random_adaptor/random_adaptor_example.c Normal file
View File

@ -0,0 +1,112 @@
/*-
* Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/selinfo.h>
#include <sys/systm.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev.h>
static int random_example_entropy_control;
#define RNG_NAME "example"
static int random_example_read(void *, int);
static void random_example_init(void);
struct random_adaptor random_example = {
.ident = "Example RNG",
.init = random_example_init,
.deinit = (random_deinit_func_t *)random_null_func,
.read = random_example_read,
.write = (random_write_func_t *)random_null_func,
.reseed = (random_reseed_func_t *)random_null_func,
.seeded = 1,
};
static void
random_example_init(void)
{
/*
* Init() is called only if this RNG was chosen to plugin in to
* random(4). In which case, we should no longer use this adaptor as
* an entropy source.
*/
random_example_entropy_control = 1;
}
/*
* Used under the license provided @ http://xkcd.com/221/
* http://creativecommons.org/licenses/by-nc/2.5/
*/
static u_char
getRandomNumber(void)
{
return 4; /* chosen by fair dice roll, guaranteed to be random */
}
static int
random_example_read(void *buf, int c)
{
u_char *b;
int count;
b = buf;
for (count = 0; count < c; count++) {
b[count] = getRandomNumber();
}
printf("returning %d bytes of pure randomness\n", c);
return (c);
}
static int
random_example_modevent(module_t mod, int type, void *unused)
{
switch (type) {
case MOD_LOAD:
/* start off by using this as an entropy source */
random_adaptor_use_as_entropy(RNG_NAME, &random_example,
&random_example_entropy_control);
random_adaptor_register(RNG_NAME, &random_example);
EVENTHANDLER_INVOKE(random_adaptor_attach, &random_example);
return (0);
}
return (EINVAL);
}
RANDOM_ADAPTOR_MODULE(random_example, random_example_modevent, 1);

2
sys/conf/files
View File

@ -2032,8 +2032,8 @@ rt2860.fw optional rt2860fw | ralfw \
clean "rt2860.fw"
dev/random/harvest.c standard
dev/random/hash.c optional random
dev/random/probe.c optional random
dev/random/random_adaptors.c standard
dev/random/pseudo_rng.c standard
dev/random/randomdev.c optional random
dev/random/randomdev_soft.c optional random
dev/random/yarrow.c optional random

62
sys/dev/random/probe.c
View File

@ -1,62 +0,0 @@
/*-
* Copyright (c) 2004 Mark R V Murray
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#if defined(__amd64__) || defined(__i386__)
#include "opt_cpu.h"
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/selinfo.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev.h>
void
random_ident_hardware(struct random_adaptor **adaptor)
{
struct random_adaptor *tmp;
int enable;
/* Set default to software (yarrow) */
*adaptor = random_adaptor_get("yarrow");
/* Then go looking for hardware */
enable = 1;
TUNABLE_INT_FETCH("hw.nehemiah_rng_enable", &enable);
if (enable && (tmp = random_adaptor_get("nehemiah")))
*adaptor = tmp;
enable = 1;
TUNABLE_INT_FETCH("hw.ivy_rng_enable", &enable);
if (enable && (tmp = random_adaptor_get("rdrand")))
*adaptor = tmp;
}

119
sys/dev/random/pseudo_rng.c Normal file
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@ -0,0 +1,119 @@
/*-
* Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/selinfo.h>
#include <sys/systm.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev.h>
static struct mtx pseudo_random_block_mtx;
static int
pseudo_random_block_read(void *buf __unused, int c __unused)
{
mtx_lock(&pseudo_random_block_mtx);
printf("random(4) device is blocking.\n");
msleep(pseudo_random_block_read, &pseudo_random_block_mtx, 0,
"block", 0);
mtx_unlock(&pseudo_random_block_mtx);
return (0);
}
static void
pseudo_random_block_init(void)
{
mtx_init(&pseudo_random_block_mtx, "sleep mtx for random_block",
NULL, MTX_DEF);
}
static void
pseudo_random_block_deinit(void)
{
mtx_destroy(&pseudo_random_block_mtx);
}
struct random_adaptor pseudo_random_block = {
.ident = "pseudo-RNG that always blocks",
.init = pseudo_random_block_init,
.deinit = pseudo_random_block_deinit,
.read = pseudo_random_block_read,
.write = (random_write_func_t *)random_null_func,
.reseed = (random_reseed_func_t *)random_null_func,
.seeded = 1,
};
static int
pseudo_random_panic_read(void *buf, int c)
{
panic("Insert a witty panic msg in here.");
return (0);
}
struct random_adaptor pseudo_random_panic = {
.ident = "pseudo-RNG that always panics on first read(2)",
.init = (random_init_func_t *)random_null_func,
.deinit = (random_deinit_func_t *)random_null_func,
.read = pseudo_random_panic_read,
.write = (random_write_func_t *)random_null_func,
.reseed = (random_reseed_func_t *)random_null_func,
.seeded = 1,
};
static int
pseudo_random_modevent(module_t mod, int type, void *unused)
{
switch (type) {
case MOD_LOAD:
random_adaptor_register("block", &pseudo_random_block);
EVENTHANDLER_INVOKE(random_adaptor_attach,
&pseudo_random_block);
random_adaptor_register("panic", &pseudo_random_panic);
return (0);
}
return (EINVAL);
}
RANDOM_ADAPTOR_MODULE(pseudo, pseudo_random_modevent, 1);

228
sys/dev/random/random_adaptors.c
View File

@ -1,6 +1,7 @@
/*-
* Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
* Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
* Copyright (c) 2004 Mark R V Murray
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -30,16 +31,20 @@ __FBSDID("$FreeBSD$");
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/random.h>
#include <sys/selinfo.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/libkern.h>
#include <sys/unistd.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev.h>
#include <dev/random/randomdev_soft.h>
#include <dev/random/random_adaptors.h>
LIST_HEAD(adaptors_head, random_adaptors);
static struct adaptors_head adaptors = LIST_HEAD_INITIALIZER(adaptors);
@ -50,6 +55,11 @@ static struct sysctl_ctx_list random_clist;
MALLOC_DEFINE(M_RANDOM_ADAPTORS, "random_adaptors", "Random adaptors buffers");
struct entropy_thread_ctx {
struct random_adaptor *adaptor;
int *control;
};
int
random_adaptor_register(const char *name, struct random_adaptor *rsp)
{
@ -57,7 +67,8 @@ random_adaptor_register(const char *name, struct random_adaptor *rsp)
KASSERT(name != NULL && rsp != NULL, ("invalid input to %s", __func__));
rpp = malloc(sizeof(struct random_adaptors), M_RANDOM_ADAPTORS, M_WAITOK);
rpp = malloc(sizeof(struct random_adaptors), M_RANDOM_ADAPTORS,
M_WAITOK);
rpp->name = name;
rpp->rsp = rsp;
@ -87,6 +98,159 @@ random_adaptor_get(const char *name)
return (rsp);
}
/*
* In the past, the logic of the random_adaptor selection was inverted, such
* that hardware RNGs would be chosen unless disabled. This routine is here to
* preserve that functionality to avoid folks losing their hardware RNGs by
* upgrading to newer kernel.
*/
static void
random_adaptor_choose_legacy(struct random_adaptor **adaptor)
{
struct random_adaptor *tmp;
int enable;
/* Then go looking for hardware */
enable = 1;
TUNABLE_INT_FETCH("hw.nehemiah_rng_enable", &enable);
if (enable && (tmp = random_adaptor_get("nehemiah")))
*adaptor = tmp;
enable = 1;
TUNABLE_INT_FETCH("hw.ivy_rng_enable", &enable);
if (enable && (tmp = random_adaptor_get("rdrand")))
*adaptor = tmp;
}
/*
* Walk a list of registered random(4) adaptors and pick the last non-selected
* one.
*
* If none are selected, use yarrow if available.
*/
void
random_adaptor_choose(struct random_adaptor **adaptor)
{
char rngs[128], *token, *cp;
struct random_adaptors *rpp;
KASSERT(adaptor != NULL, ("pre-conditions failed"));
*adaptor = NULL;
random_adaptor_choose_legacy(adaptor);
if (*adaptor != NULL)
return;
if (TUNABLE_STR_FETCH("rngs_want", rngs, sizeof(rngs))) {
cp = rngs;
while ((token = strsep(&cp, ",")) != NULL) {
if ((*adaptor = random_adaptor_get(token)) != NULL)
break;
else if (bootverbose)
printf(
"%s random adaptor is not available, skipping\n",
token);
}
}
if (*adaptor == NULL) {
/*
* Either no RNGs are prefered via rngs_want tunable, or
* no prefered RNGs are registered.
* Fallback to Yarrow.
*/
*adaptor = random_adaptor_get("yarrow");
if (*adaptor == NULL) {
/*
* Yarrow doesn't seem to be available.
* Fallback to the first thing that's on the list of
* available RNGs.
*/
sx_slock(&adaptors_lock);
rpp = LIST_FIRST(&adaptors);
if (rpp != NULL)
*adaptor = rpp->rsp;
sx_sunlock(&adaptors_lock);
}
if (bootverbose && *adaptor)
printf("Falling back to <%s> random adaptor",
(*adaptor)->ident);
}
}
static void
random_proc(void *arg)
{
struct entropy_thread_ctx *ctx;
u_char randomness[HARVESTSIZE];
int i;
ctx = (struct entropy_thread_ctx *)arg;
/* Sanity check. */
if (ctx->adaptor == NULL || ctx->adaptor->read == NULL)
return;
for (; *ctx->control == 0;) {
i = ctx->adaptor->read(randomness, sizeof(randomness));
if (i > 0)
/* Be very conservative with entropy estimation here. */
random_harvest(randomness, i, 0, 0, RANDOM_PURE);
/* Wake up every 10 secs. */
tsleep_sbt(ctx->adaptor, PWAIT | PCATCH, "-", SBT_1M / 6, 0, 0);
}
printf("<%s> entropy source is exiting\n", ctx->adaptor->ident);
free(ctx, M_RANDOM_ADAPTORS);
kproc_exit(0);
}
/*
* Use RNG's output as an entropy source for another RNG. i.e.:
* +--------+ +--------+
* | Intel | | Yarrow |
* | RDRAND +--------->| |
* +--------+ +--------+
* Very useful for seeding software RNGs with output of
* Hardware RNGs like Intel's RdRand and VIA's Padlock.
*
* Returns a handle to the newly created kernel process.
*/
void *
random_adaptor_use_as_entropy(const char *id, struct random_adaptor *adaptor,
int *control)
{
int error;
struct proc *random_chain_proc;
struct entropy_thread_ctx *ctx;
KASSERT(adaptor != NULL, ("can't obtain randomness"));
KASSERT(control != NULL, ("can't control entropy process"));
ctx = malloc(sizeof(struct entropy_thread_ctx), M_RANDOM_ADAPTORS,
M_WAITOK);
ctx->control = control;
ctx->adaptor = adaptor;
/* Start the thread */
error = kproc_create(random_proc, ctx, &random_chain_proc, RFHIGHPID,
0, "%s_entropy", id);
if (error != 0)
panic("Cannot create rng chaining thread");
return random_chain_proc;
}
static void
random_adaptors_deinit(void *unused)
{
@ -99,18 +263,28 @@ static int
random_sysctl_adaptors_handler(SYSCTL_HANDLER_ARGS)
{
struct random_adaptors *rpp;
int error;
int error, count;
error = 0;
count = error = 0;
sx_slock(&adaptors_lock);
if (LIST_EMPTY(&adaptors))
error = SYSCTL_OUT(req, "", strlen(""));
if (LIST_EMPTY(&adaptors)) {
error = SYSCTL_OUT(req, "", 0);
} else {
LIST_FOREACH(rpp, &adaptors, entries) {
if (0 != SYSCTL_OUT(req, rpp->name, strlen(rpp->name)))
break;
LIST_FOREACH(rpp, &adaptors, entries) {
error = SYSCTL_OUT(req, ",", count++ ? 1 : 0);
if (error)
break;
error = SYSCTL_OUT(req, rpp->name, strlen(rpp->name));
if (error)
break;
}
}
sx_sunlock(&adaptors_lock);
@ -118,6 +292,37 @@ random_sysctl_adaptors_handler(SYSCTL_HANDLER_ARGS)
return (error);
}
static int
random_sysctl_active_adaptor_handler(SYSCTL_HANDLER_ARGS)
{
struct random_adaptor *rsp;
struct random_adaptors *rpp;
const char *name;
int error;
name = NULL;
rsp = random_get_active_adaptor();
if (rsp != NULL) {
sx_slock(&adaptors_lock);
LIST_FOREACH(rpp, &adaptors, entries) {
if (rpp->rsp == rsp)
name = rpp->name;
}
sx_sunlock(&adaptors_lock);
}
if (rsp == NULL || name == NULL) {
error = SYSCTL_OUT(req, "", 0);
} else {
error = SYSCTL_OUT(req, name, strlen(name));
}
return (error);
}
static void
random_adaptors_init(void *unused)
{
@ -127,6 +332,11 @@ random_adaptors_init(void *unused)
NULL, 0, random_sysctl_adaptors_handler, "",
"Random Number Generator adaptors");
SYSCTL_PROC(_kern_random, OID_AUTO, active_adaptor,
CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
NULL, 0, random_sysctl_active_adaptor_handler, "",
"Active Random Number Generator Adaptor");
sx_init(&adaptors_lock, "random_adaptors");
}

3
sys/dev/random/random_adaptors.h
View File

@ -39,6 +39,9 @@ struct random_adaptors {
struct random_adaptor *random_adaptor_get(const char *);
int random_adaptor_register(const char *, struct random_adaptor *);
void random_adaptor_choose(struct random_adaptor **);
void *random_adaptor_use_as_entropy(const char *, struct random_adaptor *,
int *);
/*
* random_adaptor's should be registered prior to

10
sys/dev/random/randomdev.c
View File

@ -51,6 +51,7 @@ __FBSDID("$FreeBSD$");
#include <machine/bus.h>
#include <machine/cpu.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev.h>
#define RANDOM_MINOR 0
@ -85,6 +86,13 @@ random_null_func(void)
{
}
struct random_adaptor *
random_get_active_adaptor(void)
{
return (random_adaptor);
}
/* ARGSUSED */
static int
random_close(struct cdev *dev __unused, int flags, int fmt __unused,
@ -215,7 +223,7 @@ random_modevent(module_t mod __unused, int type, void *data __unused)
switch (type) {
case MOD_LOAD:
random_ident_hardware(&random_adaptor);
random_adaptor_choose(&random_adaptor);
if (random_adaptor == NULL) {
printf(

1
sys/dev/random/randomdev.h
View File

@ -53,3 +53,4 @@ struct random_adaptor {
extern void random_ident_hardware(struct random_adaptor **);
extern void random_null_func(void);
struct random_adaptor *random_get_active_adaptor(void);

2
sys/modules/random/Makefile
View File

@ -5,7 +5,7 @@
.PATH: ${.CURDIR}/../../crypto/sha2
KMOD= random
SRCS= randomdev.c probe.c
SRCS= randomdev.c
.if ${MACHINE} == "amd64" || ${MACHINE} == "i386"
SRCS+= nehemiah.c
SRCS+= ivy.c