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/*-
* Copyright (c) 2000-2015 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("$FreeBSD$");
#ifdef _KERNEL
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/random.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#else /* !_KERNEL */
#include <sys/param.h>
#include <sys/types.h>
#include <assert.h>
#include <inttypes.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <threads.h>
#define KASSERT(x, y) assert(x)
#define CTASSERT(x) _Static_assert(x, "CTASSERT " #x)
#endif /* _KERNEL */
#define CHACHA_EMBED
#define KEYSTREAM_ONLY
#define CHACHA_NONCE0_CTR128
#include <crypto/chacha20/chacha.c>
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha256.h>
#include <dev/random/hash.h>
#ifdef _KERNEL
#include <dev/random/randomdev.h>
#endif
/* This code presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */
CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE);
/* Validate that full Chacha IV is as large as the 128-bit counter */
_Static_assert(CHACHA_STATELEN == RANDOM_BLOCKSIZE, "");
/*
* Knob to control use of Chacha20-based PRF for Fortuna keystream primitive.
*
* Benefits include somewhat faster keystream generation compared with
* unaccelerated AES-ICM; reseeding is much cheaper than computing AES key
* schedules.
*/
bool random_chachamode __read_frequently = true;
#ifdef _KERNEL
SYSCTL_BOOL(_kern_random, OID_AUTO, use_chacha20_cipher, CTLFLAG_RDTUN,
&random_chachamode, 0,
"If non-zero, use the ChaCha20 cipher for randomdev PRF (default). "
"If zero, use AES-ICM cipher for randomdev PRF (12.x default).");
#endif
/* Initialise the hash */
void
randomdev_hash_init(struct randomdev_hash *context)
{
SHA256_Init(&context->sha);
}
/* Iterate the hash */
void
randomdev_hash_iterate(struct randomdev_hash *context, const void *data, size_t size)
{
SHA256_Update(&context->sha, data, size);
}
/* Conclude by returning the hash in the supplied <*buf> which must be
* RANDOM_KEYSIZE bytes long.
*/
void
randomdev_hash_finish(struct randomdev_hash *context, void *buf)
{
SHA256_Final(buf, &context->sha);
}
/* Initialise the encryption routine by setting up the key schedule
* from the supplied <*data> which must be RANDOM_KEYSIZE bytes of binary
* data.
*/
void
randomdev_encrypt_init(union randomdev_key *context, const void *data)
{
if (random_chachamode) {
chacha_keysetup(&context->chacha, data, RANDOM_KEYSIZE * 8);
} else {
rijndael_cipherInit(&context->cipher, MODE_ECB, NULL);
rijndael_makeKey(&context->key, DIR_ENCRYPT, RANDOM_KEYSIZE*8, data);
}
}
/*
* Create a psuedorandom output stream of 'bytecount' bytes using a CTR-mode
* cipher or similar. The 128-bit counter is supplied in the in-out parmeter
* 'ctr.' The output stream goes to 'd_out.'
*
* If AES is used, 'bytecount' is guaranteed to be a multiple of
* RANDOM_BLOCKSIZE.
*/
void
randomdev_keystream(union randomdev_key *context, uint128_t *ctr,
void *d_out, size_t bytecount)
{
size_t i, blockcount, read_chunk;
if (random_chachamode) {
uint128_t lectr;
/*
* Chacha always encodes and increments the counter little
* endian. So on BE machines, we must provide a swapped
* counter to chacha, and swap the output too.
*/
le128enc(&lectr, *ctr);
chacha_ivsetup(&context->chacha, NULL, (const void *)&lectr);
while (bytecount > 0) {
/*
* We are limited by the chacha_encrypt_bytes API to
* u32 bytes per chunk.
*/
read_chunk = MIN(bytecount,
rounddown((size_t)UINT32_MAX, CHACHA_BLOCKLEN));
chacha_encrypt_bytes(&context->chacha, NULL, d_out,
read_chunk);
d_out = (char *)d_out + read_chunk;
bytecount -= read_chunk;
}
/*
* Decode Chacha-updated LE counter to native endian and store
* it back in the caller's in-out parameter.
*/
chacha_ctrsave(&context->chacha, (void *)&lectr);
*ctr = le128dec(&lectr);
explicit_bzero(&lectr, sizeof(lectr));
} else {
KASSERT(bytecount % RANDOM_BLOCKSIZE == 0,
("%s: AES mode invalid bytecount, not a multiple of native "
"block size", __func__));
blockcount = bytecount / RANDOM_BLOCKSIZE;
for (i = 0; i < blockcount; i++) {
/*-
* FS&K - r = r|E(K,C)
* - C = C + 1
*/
rijndael_blockEncrypt(&context->cipher, &context->key,
(void *)ctr, RANDOM_BLOCKSIZE * 8, d_out);
d_out = (char *)d_out + RANDOM_BLOCKSIZE;
uint128_increment(ctr);
}
}
}
/*
* Fetch a pointer to the relevant key material and its size.
*
* This API is expected to only be used only for reseeding, where the
* endianness does not matter; the goal is to simply incorporate the key
* material into the hash iterator that will produce key'.
*
* Do not expect the buffer pointed to by this API to match the exact
* endianness, etc, as the key material that was supplied to
* randomdev_encrypt_init().
*/
void
randomdev_getkey(union randomdev_key *context, const void **keyp, size_t *szp)
{
if (!random_chachamode) {
*keyp = &context->key.keyMaterial;
*szp = context->key.keyLen / 8;
return;
}
/* Chacha20 mode */
*keyp = (const void *)&context->chacha.input[4];
/* Sanity check keysize */
if (context->chacha.input[0] == U8TO32_LITTLE(sigma) &&
context->chacha.input[1] == U8TO32_LITTLE(&sigma[4]) &&
context->chacha.input[2] == U8TO32_LITTLE(&sigma[8]) &&
context->chacha.input[3] == U8TO32_LITTLE(&sigma[12])) {
*szp = 32;
return;
}
#if 0
/*
* Included for the sake of completeness; as-implemented, Fortuna
* doesn't need or use 128-bit Chacha20.
*/
if (context->chacha->input[0] == U8TO32_LITTLE(tau) &&
context->chacha->input[1] == U8TO32_LITTLE(&tau[4]) &&
context->chacha->input[2] == U8TO32_LITTLE(&tau[8]) &&
context->chacha->input[3] == U8TO32_LITTLE(&tau[12])) {
*szp = 16;
return;
}
#endif
#ifdef _KERNEL
panic("%s: Invalid chacha20 keysize: %16D\n", __func__,
(void *)context->chacha.input, " ");
#else
raise(SIGKILL);
#endif
}
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