xref: /netbsd-src/external/mpl/bind/dist/lib/dns/hmac_link.c (revision bcda20f65a8566e103791ec395f7f499ef322704)

/*	$NetBSD: hmac_link.c,v 1.10 2025/01/26 16:25:22 christos Exp $	*/

/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0 AND ISC
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

/*
 * Copyright (C) Network Associates, Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC AND NETWORK ASSOCIATES DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE
 * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
 * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <arpa/inet.h>
#include <stdbool.h>

#include <isc/buffer.h>
#include <isc/hmac.h>
#include <isc/lex.h>
#include <isc/md.h>
#include <isc/mem.h>
#include <isc/nonce.h>
#include <isc/random.h>
#include <isc/result.h>
#include <isc/safe.h>
#include <isc/string.h>
#include <isc/util.h>

#include "dst_internal.h"
#include "dst_parse.h"

#define ISC_MD_md5    ISC_MD_MD5
#define ISC_MD_sha1   ISC_MD_SHA1
#define ISC_MD_sha224 ISC_MD_SHA224
#define ISC_MD_sha256 ISC_MD_SHA256
#define ISC_MD_sha384 ISC_MD_SHA384
#define ISC_MD_sha512 ISC_MD_SHA512

#define hmac_register_algorithm(alg)                                           \
	static isc_result_t hmac##alg##_createctx(dst_key_t *key,              \
						  dst_context_t *dctx) {       \
		return (hmac_createctx(ISC_MD_##alg, key, dctx));              \
	}                                                                      \
	static void hmac##alg##_destroyctx(dst_context_t *dctx) {              \
		hmac_destroyctx(dctx);                                         \
	}                                                                      \
	static isc_result_t hmac##alg##_adddata(dst_context_t *dctx,           \
						const isc_region_t *data) {    \
		return (hmac_adddata(dctx, data));                             \
	}                                                                      \
	static isc_result_t hmac##alg##_sign(dst_context_t *dctx,              \
					     isc_buffer_t *sig) {              \
		return (hmac_sign(dctx, sig));                                 \
	}                                                                      \
	static isc_result_t hmac##alg##_verify(dst_context_t *dctx,            \
					       const isc_region_t *sig) {      \
		return (hmac_verify(dctx, sig));                               \
	}                                                                      \
	static bool hmac##alg##_compare(const dst_key_t *key1,                 \
					const dst_key_t *key2) {               \
		return (hmac_compare(ISC_MD_##alg, key1, key2));               \
	}                                                                      \
	static isc_result_t hmac##alg##_generate(                              \
		dst_key_t *key, int pseudorandom_ok, void (*callback)(int)) {  \
		UNUSED(pseudorandom_ok);                                       \
		UNUSED(callback);                                              \
		return (hmac_generate(ISC_MD_##alg, key));                     \
	}                                                                      \
	static bool hmac##alg##_isprivate(const dst_key_t *key) {              \
		return (hmac_isprivate(key));                                  \
	}                                                                      \
	static void hmac##alg##_destroy(dst_key_t *key) { hmac_destroy(key); } \
	static isc_result_t hmac##alg##_todns(const dst_key_t *key,            \
					      isc_buffer_t *data) {            \
		return (hmac_todns(key, data));                                \
	}                                                                      \
	static isc_result_t hmac##alg##_fromdns(dst_key_t *key,                \
						isc_buffer_t *data) {          \
		return (hmac_fromdns(ISC_MD_##alg, key, data));                \
	}                                                                      \
	static isc_result_t hmac##alg##_tofile(const dst_key_t *key,           \
					       const char *directory) {        \
		return (hmac_tofile(ISC_MD_##alg, key, directory));            \
	}                                                                      \
	static isc_result_t hmac##alg##_parse(                                 \
		dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {            \
		const char *file = isc_lex_getsourcename(lexer);               \
		isc_result_t result;                                           \
		result = hmac_parse(ISC_MD_##alg, key, lexer, pub);            \
		if (result == ISC_R_SUCCESS && file != NULL) {                 \
			isc_log_write(dns_lctx, DNS_LOGCATEGORY_GENERAL,       \
				      DNS_LOGMODULE_CRYPTO, ISC_LOG_WARNING,   \
				      "%s: Use of K* file pairs for HMAC is "  \
				      "deprecated\n",                          \
				      file);                                   \
		}                                                              \
		return (result);                                               \
	}                                                                      \
	static dst_func_t hmac##alg##_functions = {                            \
		hmac##alg##_createctx,                                         \
		NULL, /*%< createctx2 */                                       \
		hmac##alg##_destroyctx,                                        \
		hmac##alg##_adddata,                                           \
		hmac##alg##_sign,                                              \
		hmac##alg##_verify,                                            \
		NULL, /*%< verify2 */                                          \
		NULL, /*%< computesecret */                                    \
		hmac##alg##_compare,                                           \
		NULL, /*%< paramcompare */                                     \
		hmac##alg##_generate,                                          \
		hmac##alg##_isprivate,                                         \
		hmac##alg##_destroy,                                           \
		hmac##alg##_todns,                                             \
		hmac##alg##_fromdns,                                           \
		hmac##alg##_tofile,                                            \
		hmac##alg##_parse,                                             \
		NULL, /*%< cleanup */                                          \
		NULL, /*%< fromlabel */                                        \
		NULL, /*%< dump */                                             \
		NULL, /*%< restore */                                          \
	};                                                                     \
	isc_result_t dst__hmac##alg##_init(dst_func_t **funcp) {               \
		REQUIRE(funcp != NULL);                                        \
		if (*funcp == NULL) {                                          \
			isc_hmac_t *ctx = isc_hmac_new();                      \
			if (isc_hmac_init(ctx, "test", 4, ISC_MD_##alg) ==     \
			    ISC_R_SUCCESS)                                     \
			{                                                      \
				*funcp = &hmac##alg##_functions;               \
			}                                                      \
			isc_hmac_free(ctx);                                    \
		}                                                              \
		return (ISC_R_SUCCESS);                                        \
	}

static isc_result_t
hmac_fromdns(const isc_md_type_t *type, dst_key_t *key, isc_buffer_t *data);

struct dst_hmac_key {
	uint8_t key[ISC_MAX_BLOCK_SIZE];
};

static isc_result_t
getkeybits(dst_key_t *key, struct dst_private_element *element) {
	uint16_t *bits = (uint16_t *)element->data;

	if (element->length != 2) {
		return DST_R_INVALIDPRIVATEKEY;
	}

	key->key_bits = ntohs(*bits);

	return ISC_R_SUCCESS;
}

static isc_result_t
hmac_createctx(const isc_md_type_t *type, const dst_key_t *key,
	       dst_context_t *dctx) {
	isc_result_t result;
	const dst_hmac_key_t *hkey = key->keydata.hmac_key;
	isc_hmac_t *ctx = isc_hmac_new(); /* Either returns or abort()s */

	result = isc_hmac_init(ctx, hkey->key, isc_md_type_get_block_size(type),
			       type);
	if (result != ISC_R_SUCCESS) {
		isc_hmac_free(ctx);
		return DST_R_UNSUPPORTEDALG;
	}

	dctx->ctxdata.hmac_ctx = ctx;
	return ISC_R_SUCCESS;
}

static void
hmac_destroyctx(dst_context_t *dctx) {
	isc_hmac_t *ctx = dctx->ctxdata.hmac_ctx;
	REQUIRE(ctx != NULL);

	isc_hmac_free(ctx);
	dctx->ctxdata.hmac_ctx = NULL;
}

static isc_result_t
hmac_adddata(const dst_context_t *dctx, const isc_region_t *data) {
	isc_result_t result;
	isc_hmac_t *ctx = dctx->ctxdata.hmac_ctx;

	REQUIRE(ctx != NULL);

	result = isc_hmac_update(ctx, data->base, data->length);
	if (result != ISC_R_SUCCESS) {
		return DST_R_OPENSSLFAILURE;
	}

	return ISC_R_SUCCESS;
}

static isc_result_t
hmac_sign(const dst_context_t *dctx, isc_buffer_t *sig) {
	isc_hmac_t *ctx = dctx->ctxdata.hmac_ctx;
	REQUIRE(ctx != NULL);
	unsigned char digest[ISC_MAX_MD_SIZE];
	unsigned int digestlen = sizeof(digest);

	if (isc_hmac_final(ctx, digest, &digestlen) != ISC_R_SUCCESS) {
		return DST_R_OPENSSLFAILURE;
	}

	if (isc_hmac_reset(ctx) != ISC_R_SUCCESS) {
		return DST_R_OPENSSLFAILURE;
	}

	if (isc_buffer_availablelength(sig) < digestlen) {
		return ISC_R_NOSPACE;
	}

	isc_buffer_putmem(sig, digest, digestlen);

	return ISC_R_SUCCESS;
}

static isc_result_t
hmac_verify(const dst_context_t *dctx, const isc_region_t *sig) {
	isc_hmac_t *ctx = dctx->ctxdata.hmac_ctx;
	unsigned char digest[ISC_MAX_MD_SIZE];
	unsigned int digestlen = sizeof(digest);

	REQUIRE(ctx != NULL);

	if (isc_hmac_final(ctx, digest, &digestlen) != ISC_R_SUCCESS) {
		return DST_R_OPENSSLFAILURE;
	}

	if (isc_hmac_reset(ctx) != ISC_R_SUCCESS) {
		return DST_R_OPENSSLFAILURE;
	}

	if (sig->length > digestlen) {
		return DST_R_VERIFYFAILURE;
	}

	return isc_safe_memequal(digest, sig->base, sig->length)
		       ? ISC_R_SUCCESS
		       : DST_R_VERIFYFAILURE;
}

static bool
hmac_compare(const isc_md_type_t *type, const dst_key_t *key1,
	     const dst_key_t *key2) {
	dst_hmac_key_t *hkey1, *hkey2;

	hkey1 = key1->keydata.hmac_key;
	hkey2 = key2->keydata.hmac_key;

	if (hkey1 == NULL && hkey2 == NULL) {
		return true;
	} else if (hkey1 == NULL || hkey2 == NULL) {
		return false;
	}

	return isc_safe_memequal(hkey1->key, hkey2->key,
				 isc_md_type_get_block_size(type));
}

static isc_result_t
hmac_generate(const isc_md_type_t *type, dst_key_t *key) {
	isc_buffer_t b;
	isc_result_t ret;
	unsigned int bytes, len;
	unsigned char data[ISC_MAX_MD_SIZE] = { 0 };

	len = isc_md_type_get_block_size(type);

	bytes = (key->key_size + 7) / 8;

	if (bytes > len) {
		bytes = len;
		key->key_size = len * 8;
	}

	isc_nonce_buf(data, bytes);

	isc_buffer_init(&b, data, bytes);
	isc_buffer_add(&b, bytes);

	ret = hmac_fromdns(type, key, &b);

	isc_safe_memwipe(data, sizeof(data));

	return ret;
}

static bool
hmac_isprivate(const dst_key_t *key) {
	UNUSED(key);
	return true;
}

static void
hmac_destroy(dst_key_t *key) {
	dst_hmac_key_t *hkey = key->keydata.hmac_key;
	isc_safe_memwipe(hkey, sizeof(*hkey));
	isc_mem_put(key->mctx, hkey, sizeof(*hkey));
	key->keydata.hmac_key = NULL;
}

static isc_result_t
hmac_todns(const dst_key_t *key, isc_buffer_t *data) {
	REQUIRE(key != NULL && key->keydata.hmac_key != NULL);
	dst_hmac_key_t *hkey = key->keydata.hmac_key;
	unsigned int bytes;

	bytes = (key->key_size + 7) / 8;
	if (isc_buffer_availablelength(data) < bytes) {
		return ISC_R_NOSPACE;
	}
	isc_buffer_putmem(data, hkey->key, bytes);

	return ISC_R_SUCCESS;
}

static isc_result_t
hmac_fromdns(const isc_md_type_t *type, dst_key_t *key, isc_buffer_t *data) {
	dst_hmac_key_t *hkey;
	unsigned int keylen;
	isc_region_t r;

	isc_buffer_remainingregion(data, &r);
	if (r.length == 0) {
		return ISC_R_SUCCESS;
	}

	hkey = isc_mem_get(key->mctx, sizeof(dst_hmac_key_t));

	memset(hkey->key, 0, sizeof(hkey->key));

	/* Hash the key if the key is longer then chosen MD block size */
	if (r.length > (unsigned int)isc_md_type_get_block_size(type)) {
		if (isc_md(type, r.base, r.length, hkey->key, &keylen) !=
		    ISC_R_SUCCESS)
		{
			isc_mem_put(key->mctx, hkey, sizeof(dst_hmac_key_t));
			return DST_R_OPENSSLFAILURE;
		}
	} else {
		memmove(hkey->key, r.base, r.length);
		keylen = r.length;
	}

	key->key_size = keylen * 8;
	key->keydata.hmac_key = hkey;

	isc_buffer_forward(data, r.length);

	return ISC_R_SUCCESS;
}

static int
hmac__get_tag_key(const isc_md_type_t *type) {
	if (type == ISC_MD_MD5) {
		return TAG_HMACMD5_KEY;
	} else if (type == ISC_MD_SHA1) {
		return TAG_HMACSHA1_KEY;
	} else if (type == ISC_MD_SHA224) {
		return TAG_HMACSHA224_KEY;
	} else if (type == ISC_MD_SHA256) {
		return TAG_HMACSHA256_KEY;
	} else if (type == ISC_MD_SHA384) {
		return TAG_HMACSHA384_KEY;
	} else if (type == ISC_MD_SHA512) {
		return TAG_HMACSHA512_KEY;
	} else {
		UNREACHABLE();
	}
}

static int
hmac__get_tag_bits(const isc_md_type_t *type) {
	if (type == ISC_MD_MD5) {
		return TAG_HMACMD5_BITS;
	} else if (type == ISC_MD_SHA1) {
		return TAG_HMACSHA1_BITS;
	} else if (type == ISC_MD_SHA224) {
		return TAG_HMACSHA224_BITS;
	} else if (type == ISC_MD_SHA256) {
		return TAG_HMACSHA256_BITS;
	} else if (type == ISC_MD_SHA384) {
		return TAG_HMACSHA384_BITS;
	} else if (type == ISC_MD_SHA512) {
		return TAG_HMACSHA512_BITS;
	} else {
		UNREACHABLE();
	}
}

static isc_result_t
hmac_tofile(const isc_md_type_t *type, const dst_key_t *key,
	    const char *directory) {
	dst_hmac_key_t *hkey;
	dst_private_t priv;
	int bytes = (key->key_size + 7) / 8;
	uint16_t bits;

	if (key->keydata.hmac_key == NULL) {
		return DST_R_NULLKEY;
	}

	if (key->external) {
		return DST_R_EXTERNALKEY;
	}

	hkey = key->keydata.hmac_key;

	priv.elements[0].tag = hmac__get_tag_key(type);
	priv.elements[0].length = bytes;
	priv.elements[0].data = hkey->key;

	bits = htons(key->key_bits);

	priv.elements[1].tag = hmac__get_tag_bits(type);
	priv.elements[1].length = sizeof(bits);
	priv.elements[1].data = (uint8_t *)&bits;

	priv.nelements = 2;

	return dst__privstruct_writefile(key, &priv, directory);
}

static int
hmac__to_dst_alg(const isc_md_type_t *type) {
	if (type == ISC_MD_MD5) {
		return DST_ALG_HMACMD5;
	} else if (type == ISC_MD_SHA1) {
		return DST_ALG_HMACSHA1;
	} else if (type == ISC_MD_SHA224) {
		return DST_ALG_HMACSHA224;
	} else if (type == ISC_MD_SHA256) {
		return DST_ALG_HMACSHA256;
	} else if (type == ISC_MD_SHA384) {
		return DST_ALG_HMACSHA384;
	} else if (type == ISC_MD_SHA512) {
		return DST_ALG_HMACSHA512;
	} else {
		UNREACHABLE();
	}
}

static isc_result_t
hmac_parse(const isc_md_type_t *type, dst_key_t *key, isc_lex_t *lexer,
	   dst_key_t *pub) {
	dst_private_t priv;
	isc_result_t result, tresult;
	isc_buffer_t b;
	isc_mem_t *mctx = key->mctx;
	unsigned int i;

	UNUSED(pub);
	/* read private key file */
	result = dst__privstruct_parse(key, hmac__to_dst_alg(type), lexer, mctx,
				       &priv);
	if (result != ISC_R_SUCCESS) {
		return result;
	}

	if (key->external) {
		result = DST_R_EXTERNALKEY;
	}

	key->key_bits = 0;
	for (i = 0; i < priv.nelements && result == ISC_R_SUCCESS; i++) {
		switch (priv.elements[i].tag) {
		case TAG_HMACMD5_KEY:
		case TAG_HMACSHA1_KEY:
		case TAG_HMACSHA224_KEY:
		case TAG_HMACSHA256_KEY:
		case TAG_HMACSHA384_KEY:
		case TAG_HMACSHA512_KEY:
			isc_buffer_init(&b, priv.elements[i].data,
					priv.elements[i].length);
			isc_buffer_add(&b, priv.elements[i].length);
			tresult = hmac_fromdns(type, key, &b);
			if (tresult != ISC_R_SUCCESS) {
				result = tresult;
			}
			break;
		case TAG_HMACMD5_BITS:
		case TAG_HMACSHA1_BITS:
		case TAG_HMACSHA224_BITS:
		case TAG_HMACSHA256_BITS:
		case TAG_HMACSHA384_BITS:
		case TAG_HMACSHA512_BITS:
			tresult = getkeybits(key, &priv.elements[i]);
			if (tresult != ISC_R_SUCCESS) {
				result = tresult;
			}
			break;
		default:
			result = DST_R_INVALIDPRIVATEKEY;
			break;
		}
	}
	dst__privstruct_free(&priv, mctx);
	isc_safe_memwipe(&priv, sizeof(priv));
	return result;
}

hmac_register_algorithm(md5);
hmac_register_algorithm(sha1);
hmac_register_algorithm(sha224);
hmac_register_algorithm(sha256);
hmac_register_algorithm(sha384);
hmac_register_algorithm(sha512);

/*! \file */