random(4): Add regression tests for uint128 implementation, Chacha CTR

Add some basic regression tests to verify behavior of both uint128
implementations at typical boundary conditions, to run on all architectures.

Test uint128 increment behavior of Chacha in keystream mode, as used by
'kern.random.use_chacha20_cipher=1' (r344913) to verify assumptions at edge
cases.  These assumptions are critical to the safety of using Chacha as a
PRF in Fortuna (as implemented).

(Chacha's use in arc4random is safe regardless of these tests, as it is
limited to far less than 4 billion blocks of output in that API.)

Reviewed by:	markm
Approved by:	secteam(gordon)
Differential Revision:	https://reviews.freebsd.org/D20392

2 files changed, 251 insertions, 0 deletions

diff --git a/tests/sys/devrandom/Makefile b/tests/sys/devrandom/Makefile
new file mode 100644
index 000000000000..db9f9d42a470
--- /dev/null
+++ b/tests/sys/devrandom/Makefile
@@ -0,0 +1,26 @@
+# $FreeBSD$
+
+.include <src.opts.mk>
+
+SDEVRANDOM=	${SRCTOP}/sys/dev/random
+.PATH:		${SDEVRANDOM}
+
+TESTSDIR=	${TESTSBASE}/sys/devrandom
+WARNS?=	6
+
+CFLAGS+=	-I${SRCTOP}/sys
+
+ATF_TESTS_C+=	uint128_test
+
+# Test Chacha CTR behavior <-> uint128
+LDADD.uint128_test+=	${SDEVRANDOM}/hash.c
+LDFLAGS.uint128_test+=	-Wno-unused-parameter
+
+# hash.c deps:
+LIBADD.uint128_test+=	md	# SHA256
+LDADD.uint128_test+=	${SRCTOP}/sys/crypto/rijndael/rijndael-alg-fst.c
+LDADD.uint128_test+=	${SRCTOP}/sys/crypto/rijndael/rijndael-api-fst.c
+LDFLAGS.uint128_test+=	-Wno-cast-align
+
+
+.include <bsd.test.mk>
diff --git a/tests/sys/devrandom/uint128_test.c b/tests/sys/devrandom/uint128_test.c
new file mode 100644
index 000000000000..0e02b227f668
--- /dev/null
+++ b/tests/sys/devrandom/uint128_test.c
@@ -0,0 +1,225 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$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) /
+		    RANDOM_BLOCKSIZE);
+		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());
+}