opnsense-src/tests/sys/devrandom/uint128_test.c
Conrad Meyer d0d71d818c random(4): Generalize algorithm-independent APIs
At a basic level, remove assumptions about the underlying algorithm (such as
output block size and reseeding requirements) from the algorithm-independent
logic in randomdev.c.  Chacha20 does not have many of the restrictions that
AES-ICM does as a PRF (Pseudo-Random Function), because it has a cipher
block size of 512 bits.  The motivation is that by generalizing the API,
Chacha is not penalized by the limitations of AES.

In READ_RANDOM_UIO, first attempt to NOWAIT allocate a large enough buffer
for the entire user request, or the maximal input we'll accept between
signal checking, whichever is smaller.  The idea is that the implementation
of any randomdev algorithm is then free to divide up large requests in
whatever fashion it sees fit.

As part of this, two responsibilities from the "algorithm-generic" randomdev
code are pushed down into the Fortuna ra_read implementation (and any other
future or out-of-tree ra_read implementations):

  1. If an algorithm needs to rekey every N bytes, it is responsible for
  handling that in ra_read(). (I.e., Fortuna's 1MB rekey interval for AES
  block generation.)

  2. If an algorithm uses a block cipher that doesn't tolerate partial-block
  requests (again, e.g., AES), it is also responsible for handling that in
  ra_read().

Several APIs are changed from u_int buffer length to the more canonical
size_t.  Several APIs are changed from taking a blockcount to a bytecount,
to permit PRFs like Chacha20 to directly generate quantities of output that
are not multiples of RANDOM_BLOCKSIZE (AES block size).

The Fortuna algorithm is changed to NOT rekey every 1MiB when in Chacha20
mode (kern.random.use_chacha20_cipher="1").  This is explicitly supported by
the math in FS&K §9.4 (Ferguson, Schneier, and Kohno; "Cryptography
Engineering"), as well as by their conclusion: "If we had a block cipher
with a 256-bit [or greater] block size, then the collisions would not
have been an issue at all."

For now, continue to break up reads into PAGE_SIZE chunks, as they were
before.  So, no functional change, mostly.

Reviewed by:	markm
Approved by:	secteam(delphij)
Differential Revision:	https://reviews.freebsd.org/D20312
2019-06-17 15:09:12 +00:00

224 lines
5.6 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>
* 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.
* 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/random.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <crypto/chacha20/chacha.h>
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha256.h>
#include <dev/random/hash.h>
#include <dev/random/uint128.h>
#include <atf-c.h>
static void
vec_u32_tole128(uint8_t dst[static 16], const uint32_t src[static 4])
{
le32enc(dst, src[0]);
le32enc(&dst[4], src[1]);
le32enc(&dst[8], src[2]);
le32enc(&dst[12], src[3]);
}
static void
le128_to_vec_u32(uint32_t dst[static 4], const uint8_t src[static 16])
{
dst[0] = le32dec(src);
dst[1] = le32dec(&src[4]);
dst[2] = le32dec(&src[8]);
dst[3] = le32dec(&src[12]);
}
static void
formatu128(char buf[static 52], uint128_t x)
{
uint8_t le128x[16];
uint32_t vx[4];
size_t sz, i;
int rc;
le128enc(le128x, x);
le128_to_vec_u32(vx, le128x);
sz = 52;
for (i = 0; i < 4; i++) {
rc = snprintf(buf, sz, "0x%x ", vx[i]);
ATF_REQUIRE(rc > 0 && (size_t)rc < sz);
buf += rc;
sz -= rc;
}
/* Delete last trailing space */
buf[-1] = '\0';
}
static void
u128_check_equality(uint128_t a, uint128_t b, const char *descr)
{
char fmtbufa[52], fmtbufb[52];
formatu128(fmtbufa, a);
formatu128(fmtbufb, b);
ATF_CHECK_MSG(uint128_equals(a, b),
"Expected: [%s] != Actual: [%s]: %s", fmtbufa, fmtbufb, descr);
}
ATF_TC_WITHOUT_HEAD(uint128_inc);
ATF_TC_BODY(uint128_inc, tc)
{
static const struct u128_inc_tc {
uint32_t input[4];
uint32_t expected[4];
const char *descr;
} tests[] = {
{
.input = { 0, 0, 0, 0 },
.expected = { 1, 0, 0, 0 },
.descr = "0 -> 1",
},
{
.input = { 1, 0, 0, 0 },
.expected = { 2, 0, 0, 0 },
.descr = "0 -> 2",
},
{
.input = { 0xff, 0, 0, 0 },
.expected = { 0x100, 0, 0, 0 },
.descr = "0xff -> 0x100 (byte carry)",
},
{
.input = { UINT32_MAX, 0, 0, 0 },
.expected = { 0, 1, 0, 0 },
.descr = "2^32 - 1 -> 2^32 (word carry)",
},
{
.input = { UINT32_MAX, UINT32_MAX, 0, 0 },
.expected = { 0, 0, 1, 0 },
.descr = "2^64 - 1 -> 2^64 (u128t_word0 carry)",
},
{
.input = { UINT32_MAX, UINT32_MAX, UINT32_MAX, 0 },
.expected = { 0, 0, 0, 1 },
.descr = "2^96 - 1 -> 2^96 (word carry)",
},
};
uint8_t inputle[16], expectedle[16];
uint128_t a;
size_t i;
for (i = 0; i < nitems(tests); i++) {
vec_u32_tole128(inputle, tests[i].input);
vec_u32_tole128(expectedle, tests[i].expected);
a = le128dec(inputle);
uint128_increment(&a);
u128_check_equality(le128dec(expectedle), a, tests[i].descr);
}
}
/*
* Test assumptions about Chacha incrementing counter in the same way as
* uint128.h
*/
ATF_TC_WITHOUT_HEAD(uint128_chacha_ctr);
ATF_TC_BODY(uint128_chacha_ctr, tc)
{
static const struct u128_chacha_tc {
uint32_t input[4];
uint32_t expected[4];
const char *descr;
} tests[] = {
{
.input = { 0, 0, 0, 0 },
.expected = { 1, 0, 0, 0 },
.descr = "Single block",
},
{
.input = { 1, 0, 0, 0 },
.expected = { 2, 0, 0, 0 },
.descr = "0 -> 2",
},
{
.input = { 0xff, 0, 0, 0 },
.expected = { 0x100, 0, 0, 0 },
.descr = "0xff -> 0x100 (byte carry)",
},
{
.input = { UINT32_MAX, 0, 0, 0 },
.expected = { 0, 1, 0, 0 },
.descr = "2^32 - 1 -> 2^32 (word carry)",
},
{
.input = { UINT32_MAX, UINT32_MAX, 0, 0 },
.expected = { 0, 0, 1, 0 },
.descr = "2^64 - 1 -> 2^64 (u128t_word0 carry)",
},
{
.input = { UINT32_MAX, UINT32_MAX, UINT32_MAX, 0 },
.expected = { 0, 0, 0, 1 },
.descr = "2^96 - 1 -> 2^96 (word carry)",
},
};
union randomdev_key context;
uint8_t inputle[16], expectedle[16], trash[CHACHA_BLOCKLEN];
uint8_t notrandomkey[RANDOM_KEYSIZE] = { 0 };
uint128_t a;
size_t i;
random_chachamode = true;
randomdev_encrypt_init(&context, notrandomkey);
for (i = 0; i < nitems(tests); i++) {
vec_u32_tole128(inputle, tests[i].input);
vec_u32_tole128(expectedle, tests[i].expected);
a = le128dec(inputle);
randomdev_keystream(&context, &a, trash, sizeof(trash));
u128_check_equality(le128dec(expectedle), a, tests[i].descr);
}
}
ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, uint128_inc);
ATF_TP_ADD_TC(tp, uint128_chacha_ctr);
return (atf_no_error());
}