xref: /freebsd/sys/contrib/openzfs/module/icp/algs/modes/ctr.c (revision dbd5678d)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or https://opensource.org/licenses/CDDL-1.0.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/zfs_context.h>
#include <modes/modes.h>
#include <sys/crypto/common.h>
#include <sys/crypto/impl.h>
#include <sys/byteorder.h>

/*
 * Encrypt and decrypt multiple blocks of data in counter mode.
 */
int
ctr_mode_contiguous_blocks(ctr_ctx_t *ctx, char *data, size_t length,
    crypto_data_t *out, size_t block_size,
    int (*cipher)(const void *ks, const uint8_t *pt, uint8_t *ct),
    void (*xor_block)(uint8_t *, uint8_t *))
{
	size_t remainder = length;
	size_t need = 0;
	uint8_t *datap = (uint8_t *)data;
	uint8_t *blockp;
	uint8_t *lastp;
	void *iov_or_mp;
	offset_t offset;
	uint8_t *out_data_1;
	uint8_t *out_data_2;
	size_t out_data_1_len;
	uint64_t lower_counter, upper_counter;

	if (length + ctx->ctr_remainder_len < block_size) {
		/* accumulate bytes here and return */
		memcpy((uint8_t *)ctx->ctr_remainder + ctx->ctr_remainder_len,
		    datap,
		    length);
		ctx->ctr_remainder_len += length;
		ctx->ctr_copy_to = datap;
		return (CRYPTO_SUCCESS);
	}

	crypto_init_ptrs(out, &iov_or_mp, &offset);

	do {
		/* Unprocessed data from last call. */
		if (ctx->ctr_remainder_len > 0) {
			need = block_size - ctx->ctr_remainder_len;

			if (need > remainder)
				return (CRYPTO_DATA_LEN_RANGE);

			memcpy(&((uint8_t *)ctx->ctr_remainder)
			    [ctx->ctr_remainder_len], datap, need);

			blockp = (uint8_t *)ctx->ctr_remainder;
		} else {
			blockp = datap;
		}

		/* ctr_cb is the counter block */
		cipher(ctx->ctr_keysched, (uint8_t *)ctx->ctr_cb,
		    (uint8_t *)ctx->ctr_tmp);

		lastp = (uint8_t *)ctx->ctr_tmp;

		/*
		 * Increment Counter.
		 */
		lower_counter = ntohll(ctx->ctr_cb[1] & ctx->ctr_lower_mask);
		lower_counter = htonll(lower_counter + 1);
		lower_counter &= ctx->ctr_lower_mask;
		ctx->ctr_cb[1] = (ctx->ctr_cb[1] & ~(ctx->ctr_lower_mask)) |
		    lower_counter;

		/* wrap around */
		if (lower_counter == 0) {
			upper_counter =
			    ntohll(ctx->ctr_cb[0] & ctx->ctr_upper_mask);
			upper_counter = htonll(upper_counter + 1);
			upper_counter &= ctx->ctr_upper_mask;
			ctx->ctr_cb[0] =
			    (ctx->ctr_cb[0] & ~(ctx->ctr_upper_mask)) |
			    upper_counter;
		}

		/*
		 * XOR encrypted counter block with the current clear block.
		 */
		xor_block(blockp, lastp);

		crypto_get_ptrs(out, &iov_or_mp, &offset, &out_data_1,
		    &out_data_1_len, &out_data_2, block_size);

		/* copy block to where it belongs */
		memcpy(out_data_1, lastp, out_data_1_len);
		if (out_data_2 != NULL) {
			memcpy(out_data_2, lastp + out_data_1_len,
			    block_size - out_data_1_len);
		}
		/* update offset */
		out->cd_offset += block_size;

		/* Update pointer to next block of data to be processed. */
		if (ctx->ctr_remainder_len != 0) {
			datap += need;
			ctx->ctr_remainder_len = 0;
		} else {
			datap += block_size;
		}

		remainder = (size_t)&data[length] - (size_t)datap;

		/* Incomplete last block. */
		if (remainder > 0 && remainder < block_size) {
			memcpy(ctx->ctr_remainder, datap, remainder);
			ctx->ctr_remainder_len = remainder;
			ctx->ctr_copy_to = datap;
			goto out;
		}
		ctx->ctr_copy_to = NULL;

	} while (remainder > 0);

out:
	return (CRYPTO_SUCCESS);
}

int
ctr_mode_final(ctr_ctx_t *ctx, crypto_data_t *out,
    int (*encrypt_block)(const void *, const uint8_t *, uint8_t *))
{
	uint8_t *lastp;
	void *iov_or_mp;
	offset_t offset;
	uint8_t *out_data_1;
	uint8_t *out_data_2;
	size_t out_data_1_len;
	uint8_t *p;
	int i;

	if (out->cd_length < ctx->ctr_remainder_len)
		return (CRYPTO_DATA_LEN_RANGE);

	encrypt_block(ctx->ctr_keysched, (uint8_t *)ctx->ctr_cb,
	    (uint8_t *)ctx->ctr_tmp);

	lastp = (uint8_t *)ctx->ctr_tmp;
	p = (uint8_t *)ctx->ctr_remainder;
	for (i = 0; i < ctx->ctr_remainder_len; i++) {
		p[i] ^= lastp[i];
	}

	crypto_init_ptrs(out, &iov_or_mp, &offset);
	crypto_get_ptrs(out, &iov_or_mp, &offset, &out_data_1,
	    &out_data_1_len, &out_data_2, ctx->ctr_remainder_len);

	memcpy(out_data_1, p, out_data_1_len);
	if (out_data_2 != NULL) {
		memcpy(out_data_2,
		    (uint8_t *)p + out_data_1_len,
		    ctx->ctr_remainder_len - out_data_1_len);
	}
	out->cd_offset += ctx->ctr_remainder_len;
	ctx->ctr_remainder_len = 0;
	return (CRYPTO_SUCCESS);
}

int
ctr_init_ctx(ctr_ctx_t *ctr_ctx, ulong_t count, uint8_t *cb,
    void (*copy_block)(uint8_t *, uint8_t *))
{
	uint64_t upper_mask = 0;
	uint64_t lower_mask = 0;

	if (count == 0 || count > 128) {
		return (CRYPTO_MECHANISM_PARAM_INVALID);
	}
	/* upper 64 bits of the mask */
	if (count >= 64) {
		count -= 64;
		upper_mask = (count == 64) ? UINT64_MAX : (1ULL << count) - 1;
		lower_mask = UINT64_MAX;
	} else {
		/* now the lower 63 bits */
		lower_mask = (1ULL << count) - 1;
	}
	ctr_ctx->ctr_lower_mask = htonll(lower_mask);
	ctr_ctx->ctr_upper_mask = htonll(upper_mask);

	copy_block(cb, (uchar_t *)ctr_ctx->ctr_cb);
	ctr_ctx->ctr_lastp = (uint8_t *)&ctr_ctx->ctr_cb[0];
	ctr_ctx->ctr_flags |= CTR_MODE;
	return (CRYPTO_SUCCESS);
}

void *
ctr_alloc_ctx(int kmflag)
{
	ctr_ctx_t *ctr_ctx;

	if ((ctr_ctx = kmem_zalloc(sizeof (ctr_ctx_t), kmflag)) == NULL)
		return (NULL);

	ctr_ctx->ctr_flags = CTR_MODE;
	return (ctr_ctx);
}