247 lines
6.9 KiB
C
247 lines
6.9 KiB
C
/* $OpenBSD: mac.c,v 1.28 2014/02/07 06:55:54 djm Exp $ */
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/*
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* Copyright (c) 2001 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <stdarg.h>
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#include <string.h>
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#include <signal.h>
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#include "xmalloc.h"
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#include "log.h"
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#include "cipher.h"
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#include "buffer.h"
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#include "key.h"
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#include "kex.h"
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#include "mac.h"
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#include "misc.h"
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#include "digest.h"
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#include "hmac.h"
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#include "umac.h"
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#include "openbsd-compat/openssl-compat.h"
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#define SSH_DIGEST 1 /* SSH_DIGEST_XXX */
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#define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
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#define SSH_UMAC128 3
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struct macalg {
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char *name;
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int type;
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int alg;
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int truncatebits; /* truncate digest if != 0 */
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int key_len; /* just for UMAC */
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int len; /* just for UMAC */
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int etm; /* Encrypt-then-MAC */
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};
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static const struct macalg macs[] = {
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/* Encrypt-and-MAC (encrypt-and-authenticate) variants */
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{ "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
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{ "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
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#ifdef HAVE_EVP_SHA256
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{ "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
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{ "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
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#endif
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{ "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
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{ "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
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{ "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 },
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{ "hmac-ripemd160@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 },
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{ "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 },
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{ "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 },
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/* Encrypt-then-MAC variants */
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{ "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
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{ "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
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#ifdef HAVE_EVP_SHA256
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{ "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
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{ "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
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#endif
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{ "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
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{ "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
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{ "hmac-ripemd160-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 },
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{ "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 },
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{ "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 },
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{ NULL, 0, 0, 0, 0, 0, 0 }
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};
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/* Returns a list of supported MACs separated by the specified char. */
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char *
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mac_alg_list(char sep)
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{
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char *ret = NULL;
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size_t nlen, rlen = 0;
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const struct macalg *m;
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for (m = macs; m->name != NULL; m++) {
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if (ret != NULL)
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ret[rlen++] = sep;
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nlen = strlen(m->name);
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ret = xrealloc(ret, 1, rlen + nlen + 2);
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memcpy(ret + rlen, m->name, nlen + 1);
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rlen += nlen;
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}
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return ret;
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}
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static void
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mac_setup_by_alg(Mac *mac, const struct macalg *macalg)
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{
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mac->type = macalg->type;
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if (mac->type == SSH_DIGEST) {
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if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
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fatal("ssh_hmac_start(alg=%d) failed", macalg->alg);
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mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
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} else {
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mac->mac_len = macalg->len / 8;
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mac->key_len = macalg->key_len / 8;
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mac->umac_ctx = NULL;
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}
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if (macalg->truncatebits != 0)
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mac->mac_len = macalg->truncatebits / 8;
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mac->etm = macalg->etm;
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}
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int
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mac_setup(Mac *mac, char *name)
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{
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const struct macalg *m;
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for (m = macs; m->name != NULL; m++) {
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if (strcmp(name, m->name) != 0)
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continue;
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if (mac != NULL) {
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mac_setup_by_alg(mac, m);
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debug2("mac_setup: setup %s", name);
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}
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return (0);
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}
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debug2("mac_setup: unknown %s", name);
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return (-1);
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}
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int
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mac_init(Mac *mac)
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{
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if (mac->key == NULL)
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fatal("%s: no key", __func__);
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switch (mac->type) {
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case SSH_DIGEST:
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if (mac->hmac_ctx == NULL ||
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ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
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return -1;
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return 0;
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case SSH_UMAC:
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mac->umac_ctx = umac_new(mac->key);
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return 0;
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case SSH_UMAC128:
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mac->umac_ctx = umac128_new(mac->key);
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return 0;
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default:
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return -1;
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}
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}
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u_char *
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mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
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{
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static union {
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u_char m[EVP_MAX_MD_SIZE];
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u_int64_t for_align;
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} u;
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u_char b[4], nonce[8];
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if (mac->mac_len > sizeof(u))
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fatal("mac_compute: mac too long %u %zu",
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mac->mac_len, sizeof(u));
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switch (mac->type) {
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case SSH_DIGEST:
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put_u32(b, seqno);
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/* reset HMAC context */
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if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
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ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
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ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
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ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
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fatal("ssh_hmac failed");
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break;
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case SSH_UMAC:
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put_u64(nonce, seqno);
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umac_update(mac->umac_ctx, data, datalen);
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umac_final(mac->umac_ctx, u.m, nonce);
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break;
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case SSH_UMAC128:
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put_u64(nonce, seqno);
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umac128_update(mac->umac_ctx, data, datalen);
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umac128_final(mac->umac_ctx, u.m, nonce);
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break;
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default:
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fatal("mac_compute: unknown MAC type");
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}
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return (u.m);
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}
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void
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mac_clear(Mac *mac)
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{
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if (mac->type == SSH_UMAC) {
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if (mac->umac_ctx != NULL)
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umac_delete(mac->umac_ctx);
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} else if (mac->type == SSH_UMAC128) {
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if (mac->umac_ctx != NULL)
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umac128_delete(mac->umac_ctx);
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} else if (mac->hmac_ctx != NULL)
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ssh_hmac_free(mac->hmac_ctx);
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mac->hmac_ctx = NULL;
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mac->umac_ctx = NULL;
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}
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/* XXX copied from ciphers_valid */
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#define MAC_SEP ","
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int
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mac_valid(const char *names)
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{
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char *maclist, *cp, *p;
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if (names == NULL || strcmp(names, "") == 0)
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return (0);
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maclist = cp = xstrdup(names);
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for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
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(p = strsep(&cp, MAC_SEP))) {
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if (mac_setup(NULL, p) < 0) {
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debug("bad mac %s [%s]", p, names);
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free(maclist);
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return (0);
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}
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}
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debug3("macs ok: [%s]", names);
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free(maclist);
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return (1);
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}
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