/* $OpenBSD: mac.c,v 1.24 2013/06/03 00:03:18 dtucker 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 <stdarg.h>

#include <string.h>

#include <signal.h>

#include "xmalloc.h"

#include "log.h"

#include "cipher.h"

#include "buffer.h"

#include "key.h"

#include "kex.h"

#include "mac.h"

#include "../openssl/include/openssl/hmac.h"

#include "misc.h"

#include "umac.h"

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

#define SSH_EVP 1 /* OpenSSL EVP-based MAC */

#define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */

#define SSH_UMAC128 3

struct macalg {

};

static const struct macalg macs[] = {

/* Encrypt-and-MAC (encrypt-and-authenticate) variants */

{ "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 },

{ "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 },

#ifdef HAVE_EVP_SHA256

{ "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 },

{ "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 },

#endif

{ "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 },

{ "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 },

#ifndef ANDROID

{ "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },

{ "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },

#endif

{ "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 },

{ "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 },

/* Encrypt-then-MAC variants */

{ "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 },

{ "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 },

#ifdef HAVE_EVP_SHA256

{ "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 },

{ "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 },

#endif

{ "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 },

{ "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 },

#ifndef ANDROID

{ "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 },

#endif

{ "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 },

{ "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 },

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

};

/* Returns a comma-separated list of supported MACs. */

char *

mac_alg_list(void)

{

char *ret = NULL;

size_t nlen, rlen = 0;

const struct macalg *m;

for (m = macs; m->name != NULL; m++) {

if (ret != NULL)

ret[rlen++] = '\n';

nlen = strlen(m->name);

ret = xrealloc(ret, 1, rlen + nlen + 2);

memcpy(ret + rlen, m->name, nlen + 1);

rlen += nlen;

}

return ret;

}

static void

mac_setup_by_alg(Mac *mac, const struct macalg *macalg)

{

int evp_len;

mac->type = macalg->type;

if (mac->type == SSH_EVP) {

mac->evp_md = macalg->mdfunc();

if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)

fatal("mac %s len %d", mac->name, evp_len);

mac->key_len = mac->mac_len = (u_int)evp_len;

} 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;

}

int

mac_setup(Mac *mac, char *name)

{

const struct macalg *m;

for (m = macs; m->name != NULL; m++) {

if (strcmp(name, m->name) != 0)

continue;

if (mac != NULL)

mac_setup_by_alg(mac, m);

debug2("mac_setup: found %s", name);

return (0);

}

debug2("mac_setup: unknown %s", name);

return (-1);

}

int

mac_init(Mac *mac)

{

if (mac->key == NULL)

fatal("mac_init: no key");

switch (mac->type) {

case SSH_EVP:

if (mac->evp_md == NULL)

return -1;

HMAC_CTX_init(&mac->evp_ctx);

HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);

return 0;

case SSH_UMAC:

mac->umac_ctx = umac_new(mac->key);

return 0;

case SSH_UMAC128:

mac->umac_ctx = umac128_new(mac->key);

return 0;

default:

return -1;

}

}

u_char *

mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)

{

static union {

u_char m[EVP_MAX_MD_SIZE];

u_int64_t for_align;

} u;

u_char b[4], nonce[8];

if (mac->mac_len > sizeof(u))

fatal("mac_compute: mac too long %u %lu",

mac->mac_len, (u_long)sizeof(u));

switch (mac->type) {

case SSH_EVP:

put_u32(b, seqno);

/* reset HMAC context */

HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);

HMAC_Update(&mac->evp_ctx, b, sizeof(b));

HMAC_Update(&mac->evp_ctx, data, datalen);

HMAC_Final(&mac->evp_ctx, u.m, NULL);

break;

case SSH_UMAC:

put_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:

fatal("mac_compute: unknown MAC type");

}

return (u.m);

}

void

mac_clear(Mac *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->evp_md != NULL)

HMAC_cleanup(&mac->evp_ctx);

mac->evp_md = 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);

maclist = cp = xstrdup(names);

for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';

(p = strsep(&cp, MAC_SEP))) {

if (mac_setup(NULL, p) < 0) {

debug("bad mac %s [%s]", p, names);

free(maclist);

return (0);

} else {

debug3("mac ok: %s [%s]", p, names);

}

}

debug3("macs ok: [%s]", names);

free(maclist);

return (1);

}