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/* $OpenBSD: mac.c,v 1.15 2008/06/13 00:51:47 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 <openssl/hmac.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 "misc.h"
#include "umac.h"
#define SSH_EVP 1 /* OpenSSL EVP-based MAC */
#define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
struct {
char *name;
int type;
const EVP_MD * (*mdfunc)(void);
int truncatebits; /* truncate digest if != 0 */
int key_len; /* just for UMAC */
int len; /* just for UMAC */
} macs[] = {
{ "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 },
{ "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 },
{ "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 },
{ "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 },
{ "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
{ "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
{ "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 },
{ NULL, 0, NULL, 0, -1, -1 }
};
static void
mac_setup_by_id(Mac *mac, int which)
{
int evp_len;
mac->type = macs[which].type;
if (mac->type == SSH_EVP) {
mac->evp_md = (*macs[which].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 = macs[which].len / 8;
mac->key_len = macs[which].key_len / 8;
mac->umac_ctx = NULL;
}
if (macs[which].truncatebits != 0)
mac->mac_len = macs[which].truncatebits / 8;
}
int
mac_setup(Mac *mac, char *name)
{
int i;
for (i = 0; macs[i].name; i++) {
if (strcmp(name, macs[i].name) == 0) {
if (mac != NULL)
mac_setup_by_id(mac, i);
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_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;
default:
return -1;
}
}
u_char *
mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
{
static u_char m[EVP_MAX_MD_SIZE];
u_char b[4], nonce[8];
if (mac->mac_len > sizeof(m))
fatal("mac_compute: mac too long %u %lu",
mac->mac_len, (u_long)sizeof(m));
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, m, NULL);
break;
case SSH_UMAC:
put_u64(nonce, seqno);
umac_update(mac->umac_ctx, data, datalen);
umac_final(mac->umac_ctx, m, nonce);
break;
default:
fatal("mac_compute: unknown MAC type");
}
return (m);
}
void
mac_clear(Mac *mac)
{
if (mac->type == SSH_UMAC) {
if (mac->umac_ctx != NULL)
umac_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);
xfree(maclist);
return (0);
} else {
debug3("mac ok: %s [%s]", p, names);
}
}
debug3("macs ok: [%s]", names);
xfree(maclist);
return (1);
}
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