mac.c - third_party/openssh-portable - Git at Google

 /* $OpenBSD: mac.c,v 1.35 2019/09/06 04:53:27 djm Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  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 ``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 "includes.h"

 #include <sys/types.h>

 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>

 #include "digest.h"
 #include "hmac.h"
 #include "umac.h"
 #include "mac.h"
 #include "misc.h"
 #include "ssherr.h"
 #include "sshbuf.h"

 #include "openbsd-compat/openssl-compat.h"

 #define SSH_DIGEST	1	/* SSH_DIGEST_XXX */
 #define SSH_UMAC	2	/* UMAC (not integrated with OpenSSL) */
 #define SSH_UMAC128	3

 struct macalg {
 	char		*name;
 	int		type;
 	int		alg;
 	int		truncatebits;	/* truncate digest if != 0 */
 	int		key_len;	/* just for UMAC */
 	int		len;		/* just for UMAC */
 	int		etm;		/* Encrypt-then-MAC */
 };

 static const struct macalg macs[] = {
 	/* Encrypt-and-MAC (encrypt-and-authenticate) variants */
 	{ "hmac-sha1",				SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
 	{ "hmac-sha1-96",			SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
 	{ "hmac-sha2-256",			SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
 	{ "hmac-sha2-512",			SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
 	{ "hmac-md5",				SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
 	{ "hmac-md5-96",			SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
 	{ "umac-64@openssh.com",		SSH_UMAC, 0, 0, 128, 64, 0 },
 	{ "umac-128@openssh.com",		SSH_UMAC128, 0, 0, 128, 128, 0 },

 	/* Encrypt-then-MAC variants */
 	{ "hmac-sha1-etm@openssh.com",		SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
 	{ "hmac-sha1-96-etm@openssh.com",	SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
 	{ "hmac-sha2-256-etm@openssh.com",	SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
 	{ "hmac-sha2-512-etm@openssh.com",	SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
 	{ "hmac-md5-etm@openssh.com",		SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
 	{ "hmac-md5-96-etm@openssh.com",	SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
 	{ "umac-64-etm@openssh.com",		SSH_UMAC, 0, 0, 128, 64, 1 },
 	{ "umac-128-etm@openssh.com",		SSH_UMAC128, 0, 0, 128, 128, 1 },

 	{ NULL,					0, 0, 0, 0, 0, 0 }
 };

 /* Returns a list of supported MACs separated by the specified char. */
 char *
 mac_alg_list(char sep)
 {
 	char *ret = NULL, *tmp;
 	size_t nlen, rlen = 0;
 	const struct macalg *m;

 	for (m = macs; m->name != NULL; m++) {
 		if (ret != NULL)
 			ret[rlen++] = sep;
 		nlen = strlen(m->name);
 		if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
 			free(ret);
 			return NULL;
 		}
 		ret = tmp;
 		memcpy(ret + rlen, m->name, nlen + 1);
 		rlen += nlen;
 	}
 	return ret;
 }

 static int
 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
 {
 	mac->type = macalg->type;
 	if (mac->type == SSH_DIGEST) {
 		if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
 			return SSH_ERR_ALLOC_FAIL;
 		mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
 	} else {
 		mac->mac_len = macalg->len / 8;
 		mac->key_len = macalg->key_len / 8;
 		mac->umac_ctx = NULL;
 	}
 	if (macalg->truncatebits != 0)
 		mac->mac_len = macalg->truncatebits / 8;
 	mac->etm = macalg->etm;
 	return 0;
 }

 int
 mac_setup(struct sshmac *mac, char *name)
 {
 	const struct macalg *m;

 	for (m = macs; m->name != NULL; m++) {
 		if (strcmp(name, m->name) != 0)
 			continue;
 		if (mac != NULL)
 			return mac_setup_by_alg(mac, m);
 		return 0;
 	}
 	return SSH_ERR_INVALID_ARGUMENT;
 }

 int
 mac_init(struct sshmac *mac)
 {
 	if (mac->key == NULL)
 		return SSH_ERR_INVALID_ARGUMENT;
 	switch (mac->type) {
 	case SSH_DIGEST:
 		if (mac->hmac_ctx == NULL ||
 		    ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
 			return SSH_ERR_INVALID_ARGUMENT;
 		return 0;
 	case SSH_UMAC:
 		if ((mac->umac_ctx = umac_new(mac->key)) == NULL)
 			return SSH_ERR_ALLOC_FAIL;
 		return 0;
 	case SSH_UMAC128:
 		if ((mac->umac_ctx = umac128_new(mac->key)) == NULL)
 			return SSH_ERR_ALLOC_FAIL;
 		return 0;
 	default:
 		return SSH_ERR_INVALID_ARGUMENT;
 	}
 }

 int
 mac_compute(struct sshmac *mac, u_int32_t seqno,
     const u_char *data, int datalen,
     u_char *digest, size_t dlen)
 {
 	static union {
 		u_char m[SSH_DIGEST_MAX_LENGTH];
 		u_int64_t for_align;
 	} u;
 	u_char b[4];
 	u_char nonce[8];

 	if (mac->mac_len > sizeof(u))
 		return SSH_ERR_INTERNAL_ERROR;

 	switch (mac->type) {
 	case SSH_DIGEST:
 		put_u32(b, seqno);
 		/* reset HMAC context */
 		if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
 		    ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
 		    ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
 		    ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
 			return SSH_ERR_LIBCRYPTO_ERROR;
 		break;
 	case SSH_UMAC:
 		POKE_U64(nonce, seqno);
 		umac_update(mac->umac_ctx, data, datalen);
 		umac_final(mac->umac_ctx, u.m, nonce);
 		break;
 	case SSH_UMAC128:
 		put_u64(nonce, seqno);
 		umac128_update(mac->umac_ctx, data, datalen);
 		umac128_final(mac->umac_ctx, u.m, nonce);
 		break;
 	default:
 		return SSH_ERR_INVALID_ARGUMENT;
 	}
 	if (digest != NULL) {
 		if (dlen > mac->mac_len)
 			dlen = mac->mac_len;
 		memcpy(digest, u.m, dlen);
 	}
 	return 0;
 }

 int
 mac_check(struct sshmac *mac, u_int32_t seqno,
     const u_char *data, size_t dlen,
     const u_char *theirmac, size_t mlen)
 {
 	u_char ourmac[SSH_DIGEST_MAX_LENGTH];
 	int r;

 	if (mac->mac_len > mlen)
 		return SSH_ERR_INVALID_ARGUMENT;
 	if ((r = mac_compute(mac, seqno, data, dlen,
 	    ourmac, sizeof(ourmac))) != 0)
 		return r;
 	if (timingsafe_bcmp(ourmac, theirmac, mac->mac_len) != 0)
 		return SSH_ERR_MAC_INVALID;
 	return 0;
 }

 void
 mac_clear(struct sshmac *mac)
 {
 	if (mac->type == SSH_UMAC) {
 		if (mac->umac_ctx != NULL)
 			umac_delete(mac->umac_ctx);
 	} else if (mac->type == SSH_UMAC128) {
 		if (mac->umac_ctx != NULL)
 			umac128_delete(mac->umac_ctx);
 	} else if (mac->hmac_ctx != NULL)
 		ssh_hmac_free(mac->hmac_ctx);
 	mac->hmac_ctx = NULL;
 	mac->umac_ctx = NULL;
 }

 /* XXX copied from ciphers_valid */
 #define	MAC_SEP	","
 int
 mac_valid(const char *names)
 {
 	char *maclist, *cp, *p;

 	if (names == NULL || strcmp(names, "") == 0)
 		return 0;
 	if ((maclist = cp = strdup(names)) == NULL)
 		return 0;
 	for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
 	    (p = strsep(&cp, MAC_SEP))) {
 		if (mac_setup(NULL, p) < 0) {
 			free(maclist);
 			return 0;
 		}
 	}
 	free(maclist);
 	return 1;
 }
	/* $OpenBSD: mac.c,v 1.35 2019/09/06 04:53:27 djm Exp $ */
	/*
	* Copyright (c) 2001 Markus Friedl. 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 ``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 "includes.h"

	#include <sys/types.h>

	#include <stdlib.h>
	#include <string.h>
	#include <stdio.h>

	#include "digest.h"
	#include "hmac.h"
	#include "umac.h"
	#include "mac.h"
	#include "misc.h"
	#include "ssherr.h"
	#include "sshbuf.h"

	#include "openbsd-compat/openssl-compat.h"

	#define SSH_DIGEST 1 /* SSH_DIGEST_XXX */
	#define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
	#define SSH_UMAC128 3

	struct macalg {
	char *name;
	int type;
	int alg;
	int truncatebits; /* truncate digest if != 0 */
	int key_len; /* just for UMAC */
	int len; /* just for UMAC */
	int etm; /* Encrypt-then-MAC */
	};

	static const struct macalg macs[] = {
	/* Encrypt-and-MAC (encrypt-and-authenticate) variants */
	{ "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
	{ "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
	{ "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
	{ "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
	{ "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
	{ "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
	{ "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 },
	{ "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 },

	/* Encrypt-then-MAC variants */
	{ "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
	{ "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
	{ "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
	{ "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
	{ "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
	{ "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
	{ "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 },
	{ "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 },

	{ NULL, 0, 0, 0, 0, 0, 0 }
	};

	/* Returns a list of supported MACs separated by the specified char. */
	char *
	mac_alg_list(char sep)
	{
	char ret = NULL, tmp;
	size_t nlen, rlen = 0;
	const struct macalg *m;

	for (m = macs; m->name != NULL; m++) {
	if (ret != NULL)
	ret[rlen++] = sep;
	nlen = strlen(m->name);
	if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
	free(ret);
	return NULL;
	}
	ret = tmp;
	memcpy(ret + rlen, m->name, nlen + 1);
	rlen += nlen;
	}
	return ret;
	}

	static int
	mac_setup_by_alg(struct sshmac mac, const struct macalg macalg)
	{
	mac->type = macalg->type;
	if (mac->type == SSH_DIGEST) {
	if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
	return SSH_ERR_ALLOC_FAIL;
	mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
	} else {
	mac->mac_len = macalg->len / 8;
	mac->key_len = macalg->key_len / 8;
	mac->umac_ctx = NULL;
	}
	if (macalg->truncatebits != 0)
	mac->mac_len = macalg->truncatebits / 8;
	mac->etm = macalg->etm;
	return 0;
	}

	int
	mac_setup(struct sshmac mac, char name)
	{
	const struct macalg *m;

	for (m = macs; m->name != NULL; m++) {
	if (strcmp(name, m->name) != 0)
	continue;
	if (mac != NULL)
	return mac_setup_by_alg(mac, m);
	return 0;
	}
	return SSH_ERR_INVALID_ARGUMENT;
	}

	int
	mac_init(struct sshmac *mac)
	{
	if (mac->key == NULL)
	return SSH_ERR_INVALID_ARGUMENT;
	switch (mac->type) {
	case SSH_DIGEST:
	if (mac->hmac_ctx == NULL \|\|
	ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
	return SSH_ERR_INVALID_ARGUMENT;
	return 0;
	case SSH_UMAC:
	if ((mac->umac_ctx = umac_new(mac->key)) == NULL)
	return SSH_ERR_ALLOC_FAIL;
	return 0;
	case SSH_UMAC128:
	if ((mac->umac_ctx = umac128_new(mac->key)) == NULL)
	return SSH_ERR_ALLOC_FAIL;
	return 0;
	default:
	return SSH_ERR_INVALID_ARGUMENT;
	}
	}

	int
	mac_compute(struct sshmac *mac, u_int32_t seqno,
	const u_char *data, int datalen,
	u_char *digest, size_t dlen)
	{
	static union {
	u_char m[SSH_DIGEST_MAX_LENGTH];
	u_int64_t for_align;
	} u;
	u_char b[4];
	u_char nonce[8];

	if (mac->mac_len > sizeof(u))
	return SSH_ERR_INTERNAL_ERROR;

	switch (mac->type) {
	case SSH_DIGEST:
	put_u32(b, seqno);
	/* reset HMAC context */
	if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 \|\|
	ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 \|\|
	ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 \|\|
	ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
	return SSH_ERR_LIBCRYPTO_ERROR;
	break;
	case SSH_UMAC:
	POKE_U64(nonce, seqno);
	umac_update(mac->umac_ctx, data, datalen);
	umac_final(mac->umac_ctx, u.m, nonce);
	break;
	case SSH_UMAC128:
	put_u64(nonce, seqno);
	umac128_update(mac->umac_ctx, data, datalen);
	umac128_final(mac->umac_ctx, u.m, nonce);
	break;
	default:
	return SSH_ERR_INVALID_ARGUMENT;
	}
	if (digest != NULL) {
	if (dlen > mac->mac_len)
	dlen = mac->mac_len;
	memcpy(digest, u.m, dlen);
	}
	return 0;
	}

	int
	mac_check(struct sshmac *mac, u_int32_t seqno,
	const u_char *data, size_t dlen,
	const u_char *theirmac, size_t mlen)
	{
	u_char ourmac[SSH_DIGEST_MAX_LENGTH];
	int r;

	if (mac->mac_len > mlen)
	return SSH_ERR_INVALID_ARGUMENT;
	if ((r = mac_compute(mac, seqno, data, dlen,
	ourmac, sizeof(ourmac))) != 0)
	return r;
	if (timingsafe_bcmp(ourmac, theirmac, mac->mac_len) != 0)
	return SSH_ERR_MAC_INVALID;
	return 0;
	}

	void
	mac_clear(struct sshmac *mac)
	{
	if (mac->type == SSH_UMAC) {
	if (mac->umac_ctx != NULL)
	umac_delete(mac->umac_ctx);
	} else if (mac->type == SSH_UMAC128) {
	if (mac->umac_ctx != NULL)
	umac128_delete(mac->umac_ctx);
	} else if (mac->hmac_ctx != NULL)
	ssh_hmac_free(mac->hmac_ctx);
	mac->hmac_ctx = NULL;
	mac->umac_ctx = NULL;
	}

	/* XXX copied from ciphers_valid */
	#define MAC_SEP ","
	int
	mac_valid(const char *names)
	{
	char maclist, cp, *p;

	if (names == NULL \|\| strcmp(names, "") == 0)
	return 0;
	if ((maclist = cp = strdup(names)) == NULL)
	return 0;
	for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
	(p = strsep(&cp, MAC_SEP))) {
	if (mac_setup(NULL, p) < 0) {
	free(maclist);
	return 0;
	}
	}
	free(maclist);
	return 1;
	}