crypto/dist/ssh/mac.c

   1 /*      $NetBSD: mac.c,v 1.12 2007/12/20 14:14:04 martin Exp $  */
   2 /* $OpenBSD: mac.c,v 1.15 2008/06/13 00:51:47 dtucker Exp $ */
   3 /*
   4  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28 __RCSID("$NetBSD: mac.c,v 1.12 2007/12/20 14:14:04 martin Exp $");
  29 #include <sys/types.h>
  30
  31 #include <openssl/hmac.h>
  32
  33 #include <string.h>
  34 #include <signal.h>
  35
  36 #include "xmalloc.h"
  37 #include "log.h"
  38 #include "cipher.h"
  39 #include "buffer.h"
  40 #include "key.h"
  41 #include "kex.h"
  42 #include "mac.h"
  43 #include "misc.h"
  44
  45 #ifdef UMAC_HAS_BEEN_UNBROKEN
  46 #include "umac.h"
  47 #endif
  48
  49 #define SSH_EVP         1       /* OpenSSL EVP-based MAC */
  50 #define SSH_UMAC        2       /* UMAC (not integrated with OpenSSL) */
  51
  52 struct {
  53         char            *name;
  54         int             type;
  55         const EVP_MD *  (*mdfunc)(void);
  56         int             truncatebits;   /* truncate digest if != 0 */
  57         int             key_len;        /* just for UMAC */
  58         int             len;            /* just for UMAC */
  59 } macs[] = {
  60         { "hmac-sha1",                  SSH_EVP, EVP_sha1, 0, -1, -1 },
  61         { "hmac-sha1-96",               SSH_EVP, EVP_sha1, 96, -1, -1 },
  62         { "hmac-md5",                   SSH_EVP, EVP_md5, 0, -1, -1 },
  63         { "hmac-md5-96",                SSH_EVP, EVP_md5, 96, -1, -1 },
  64         { "hmac-ripemd160",             SSH_EVP, EVP_ripemd160, 0, -1, -1 },
  65         { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
  66 #ifdef UMAC_HAS_BEEN_UNBROKEN
  67         { "umac-64@openssh.com",        SSH_UMAC, NULL, 0, 128, 64 },
  68 #endif
  69         { NULL,                         0, NULL, 0, -1, -1 }
  70 };
  71
  72 static void
  73 mac_setup_by_id(Mac *mac, int which)
  74 {
  75         int evp_len;
  76         mac->type = macs[which].type;
  77         if (mac->type == SSH_EVP) {
  78                 mac->evp_md = (*macs[which].mdfunc)();
  79                 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
  80                         fatal("mac %s len %d", mac->name, evp_len);
  81                 mac->key_len = mac->mac_len = (u_int)evp_len;
  82         } else {
  83                 mac->mac_len = macs[which].len / 8;
  84                 mac->key_len = macs[which].key_len / 8;
  85                 mac->umac_ctx = NULL;
  86         }
  87         if (macs[which].truncatebits != 0)
  88                 mac->mac_len = macs[which].truncatebits / 8;
  89 }
  90
  91 int
  92 mac_setup(Mac *mac, char *name)
  93 {
  94         int i;
  95
  96         for (i = 0; macs[i].name; i++) {
  97                 if (strcmp(name, macs[i].name) == 0) {
  98                         if (mac != NULL)
  99                                 mac_setup_by_id(mac, i);
 100                         debug2("mac_setup: found %s", name);
 101                         return (0);
 102                 }
 103         }
 104         debug2("mac_setup: unknown %s", name);
 105         return (-1);
 106 }
 107
 108 int
 109 mac_init(Mac *mac)
 110 {
 111         if (mac->key == NULL)
 112                 fatal("mac_init: no key");
 113         switch (mac->type) {
 114         case SSH_EVP:
 115                 if (mac->evp_md == NULL)
 116                         return -1;
 117                 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
 118                 return 0;
 119 #ifdef UMAC_HAS_BEEN_UNBROKEN
 120         case SSH_UMAC:
 121                 mac->umac_ctx = umac_new(mac->key);
 122                 return 0;
 123 #endif
 124         default:
 125                 return -1;
 126         }
 127 }
 128
 129 u_char *
 130 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
 131 {
 132         static u_char m[EVP_MAX_MD_SIZE];
 133         u_char b[4];
 134 #ifdef UMAC_HAS_BEEN_UNBROKEN
 135         u_char nonce[8];
 136 #endif
 137
 138         if (mac->mac_len > sizeof(m))
 139                 fatal("mac_compute: mac too long %u %lu",
 140                     mac->mac_len, (u_long)sizeof(m));
 141
 142         switch (mac->type) {
 143         case SSH_EVP:
 144                 put_u32(b, seqno);
 145                 /* reset HMAC context */
 146                 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
 147                 HMAC_Update(&mac->evp_ctx, b, sizeof(b));
 148                 HMAC_Update(&mac->evp_ctx, data, datalen);
 149                 HMAC_Final(&mac->evp_ctx, m, NULL);
 150                 break;
 151 #ifdef UMAC_HAS_BEEN_UNBROKEN
 152         case SSH_UMAC:
 153                 put_u64(nonce, seqno);
 154                 umac_update(mac->umac_ctx, data, datalen);
 155                 umac_final(mac->umac_ctx, m, nonce);
 156                 break;
 157 #endif
 158         default:
 159                 fatal("mac_compute: unknown MAC type");
 160         }
 161         return (m);
 162 }
 163
 164 void
 165 mac_clear(Mac *mac)
 166 {
 167 #ifdef UMAC_HAS_BEEN_UNBROKEN
 168         if (mac->type == SSH_UMAC) {
 169                 if (mac->umac_ctx != NULL)
 170                         umac_delete(mac->umac_ctx);
 171         } else
 172 #endif
 173         if (mac->evp_md != NULL)
 174                 HMAC_cleanup(&mac->evp_ctx);
 175         mac->evp_md = NULL;
 176         mac->umac_ctx = NULL;
 177 }
 178
 179 /* XXX copied from ciphers_valid */
 180 #define MAC_SEP ","
 181 int
 182 mac_valid(const char *names)
 183 {
 184         char *maclist, *cp, *p;
 185
 186         if (names == NULL || strcmp(names, "") == 0)
 187                 return (0);
 188         maclist = cp = xstrdup(names);
 189         for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
 190             (p = strsep(&cp, MAC_SEP))) {
 191                 if (mac_setup(NULL, p) < 0) {
 192                         debug("bad mac %s [%s]", p, names);
 193                         xfree(maclist);
 194                         return (0);
 195                 } else {
 196                         debug3("mac ok: %s [%s]", p, names);
 197                 }
 198         }
 199         debug3("macs ok: [%s]", names);
 200         xfree(maclist);
 201         return (1);
 202 }