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selftests: vDSO: open code basic chacha instead of linking to libsodium

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Linking to libsodium makes building this test annoying in cross
compilation environments and is just way too much. Since this is just a
basic correctness test, simply open code a simple, unoptimized, dumb
chacha, rather than linking to libsodium.

This also fixes a correctness issue on big endian systems. The kernel's
random.c doesn't bother doing a le32_to_cpu operation on the random
bytes that are passed as the key, and consequently neither does
vgetrandom-chacha.S. However, libsodium's chacha _does_ do this, since
it takes the key as an array of bytes. This meant that the test was
broken on big endian systems, which this commit rectifies.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2024-08-28 15:49:32 +02:00
parent 6fd13b282f
commit 7fe5b3e4e7
2 changed files with 45 additions and 9 deletions
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7
tools/testing/selftests/vDSO/Makefile
View File

@ -1,8 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
uname_M := $(shell uname -m 2>/dev/null || echo not)
ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
SODIUM_LIBS := $(shell pkg-config --libs libsodium 2>/dev/null)
SODIUM_CFLAGS := $(shell pkg-config --cflags libsodium 2>/dev/null)
TEST_GEN_PROGS := vdso_test_gettimeofday
TEST_GEN_PROGS += vdso_test_getcpu
@ -14,10 +12,8 @@ endif
TEST_GEN_PROGS += vdso_test_correctness
ifeq ($(uname_M),x86_64)
TEST_GEN_PROGS += vdso_test_getrandom
ifneq ($(SODIUM_LIBS),)
TEST_GEN_PROGS += vdso_test_chacha
endif
endif
CFLAGS := -std=gnu99
@ -43,8 +39,7 @@ $(OUTPUT)/vdso_test_getrandom: CFLAGS += -isystem $(top_srcdir)/tools/include \
-isystem $(top_srcdir)/include/uapi
$(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(ARCH)/vdso/vgetrandom-chacha.S
$(OUTPUT)/vdso_test_chacha: LDLIBS += $(SODIUM_LIBS)
$(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
-idirafter $(top_srcdir)/arch/$(ARCH)/include \
-idirafter $(top_srcdir)/include \
-D__ASSEMBLY__ -Wa,--noexecstack $(SODIUM_CFLAGS)
-D__ASSEMBLY__ -Wa,--noexecstack

47
tools/testing/selftests/vDSO/vdso_test_chacha.c
View File

@ -3,13 +3,55 @@
* Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include <sodium/crypto_stream_chacha20.h>
#include <tools/le_byteshift.h>
#include <sys/random.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include "../kselftest.h"
static uint32_t rol32(uint32_t word, unsigned int shift)
{
return (word << (shift & 31)) | (word >> ((-shift) & 31));
}
static void reference_chacha20_blocks(uint8_t *dst_bytes, const uint32_t *key, size_t nblocks)
{
uint32_t s[16] = {
0x61707865U, 0x3320646eU, 0x79622d32U, 0x6b206574U,
key[0], key[1], key[2], key[3], key[4], key[5], key[6], key[7]
};
while (nblocks--) {
uint32_t x[16];
memcpy(x, s, sizeof(x));
for (unsigned int r = 0; r < 20; r += 2) {
#define QR(a, b, c, d) ( \
x[a] += x[b], \
x[d] = rol32(x[d] ^ x[a], 16), \
x[c] += x[d], \
x[b] = rol32(x[b] ^ x[c], 12), \
x[a] += x[b], \
x[d] = rol32(x[d] ^ x[a], 8), \
x[c] += x[d], \
x[b] = rol32(x[b] ^ x[c], 7))
QR(0, 4, 8, 12);
QR(1, 5, 9, 13);
QR(2, 6, 10, 14);
QR(3, 7, 11, 15);
QR(0, 5, 10, 15);
QR(1, 6, 11, 12);
QR(2, 7, 8, 13);
QR(3, 4, 9, 14);
}
for (unsigned int i = 0; i < 16; ++i, dst_bytes += sizeof(uint32_t))
put_unaligned_le32(x[i] + s[i], dst_bytes);
if (!++s[12])
++s[13];
}
}
typedef uint8_t u8;
typedef uint32_t u32;
typedef uint64_t u64;
@ -18,7 +60,6 @@ typedef uint64_t u64;
int main(int argc, char *argv[])
{
enum { TRIALS = 1000, BLOCKS = 128, BLOCK_SIZE = 64 };
static const uint8_t nonce[8] = { 0 };
uint32_t counter[2];
uint32_t key[8];
uint8_t output1[BLOCK_SIZE * BLOCKS], output2[BLOCK_SIZE * BLOCKS];
@ -31,7 +72,7 @@ int main(int argc, char *argv[])
printf("getrandom() failed!\n");
return KSFT_SKIP;
}
crypto_stream_chacha20(output1, sizeof(output1), nonce, (uint8_t *)key);
reference_chacha20_blocks(output1, key, BLOCKS);
for (unsigned int split = 0; split < BLOCKS; ++split) {
memset(output2, 'X', sizeof(output2));
memset(counter, 0, sizeof(counter));