crypto/openssh/mac.c

   1 /* $OpenBSD: mac.c,v 1.16 2011/08/02 01:22:11 djm Exp $ */
   2 /*
   3  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29
  30 #include <openssl/hmac.h>
  31
  32 #include <stdarg.h>
  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 #include "umac.h"
  46
  47 #define SSH_EVP         1       /* OpenSSL EVP-based MAC */
  48 #define SSH_UMAC        2       /* UMAC (not integrated with OpenSSL) */
  49
  50 struct {
  51         char            *name;
  52         int             type;
  53         const EVP_MD *  (*mdfunc)(void);
  54         int             truncatebits;   /* truncate digest if != 0 */
  55         int             key_len;        /* just for UMAC */
  56         int             len;            /* just for UMAC */
  57 } macs[] = {
  58         { "hmac-sha1",                  SSH_EVP, EVP_sha1, 0, -1, -1 },
  59         { "hmac-sha1-96",               SSH_EVP, EVP_sha1, 96, -1, -1 },
  60 #ifdef HAVE_EVP_SHA256
  61         { "hmac-sha2-256",              SSH_EVP, EVP_sha256, 0, -1, -1 },
  62         { "hmac-sha2-256-96",           SSH_EVP, EVP_sha256, 96, -1, -1 },
  63         { "hmac-sha2-512",              SSH_EVP, EVP_sha512, 0, -1, -1 },
  64         { "hmac-sha2-512-96",           SSH_EVP, EVP_sha512, 96, -1, -1 },
  65 #endif
  66         { "hmac-md5",                   SSH_EVP, EVP_md5, 0, -1, -1 },
  67         { "hmac-md5-96",                SSH_EVP, EVP_md5, 96, -1, -1 },
  68         { "hmac-ripemd160",             SSH_EVP, EVP_ripemd160, 0, -1, -1 },
  69         { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
  70         { "umac-64@openssh.com",        SSH_UMAC, NULL, 0, 128, 64 },
  71         { NULL,                         0, NULL, 0, -1, -1 }
  72 };
  73
  74 static void
  75 mac_setup_by_id(Mac *mac, int which)
  76 {
  77         int evp_len;
  78         mac->type = macs[which].type;
  79         if (mac->type == SSH_EVP) {
  80                 mac->evp_md = (*macs[which].mdfunc)();
  81                 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
  82                         fatal("mac %s len %d", mac->name, evp_len);
  83                 mac->key_len = mac->mac_len = (u_int)evp_len;
  84         } else {
  85                 mac->mac_len = macs[which].len / 8;
  86                 mac->key_len = macs[which].key_len / 8;
  87                 mac->umac_ctx = NULL;
  88         }
  89         if (macs[which].truncatebits != 0)
  90                 mac->mac_len = macs[which].truncatebits / 8;
  91 }
  92
  93 int
  94 mac_setup(Mac *mac, char *name)
  95 {
  96         int i;
  97
  98         for (i = 0; macs[i].name; i++) {
  99                 if (strcmp(name, macs[i].name) == 0) {
 100                         if (mac != NULL)
 101                                 mac_setup_by_id(mac, i);
 102                         debug2("mac_setup: found %s", name);
 103                         return (0);
 104                 }
 105         }
 106         debug2("mac_setup: unknown %s", name);
 107         return (-1);
 108 }
 109
 110 int
 111 mac_init(Mac *mac)
 112 {
 113         if (mac->key == NULL)
 114                 fatal("mac_init: no key");
 115         switch (mac->type) {
 116         case SSH_EVP:
 117                 if (mac->evp_md == NULL)
 118                         return -1;
 119                 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
 120                 return 0;
 121         case SSH_UMAC:
 122                 mac->umac_ctx = umac_new(mac->key);
 123                 return 0;
 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], nonce[8];
 134
 135         if (mac->mac_len > sizeof(m))
 136                 fatal("mac_compute: mac too long %u %lu",
 137                     mac->mac_len, (u_long)sizeof(m));
 138
 139         switch (mac->type) {
 140         case SSH_EVP:
 141                 put_u32(b, seqno);
 142                 /* reset HMAC context */
 143                 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
 144                 HMAC_Update(&mac->evp_ctx, b, sizeof(b));
 145                 HMAC_Update(&mac->evp_ctx, data, datalen);
 146                 HMAC_Final(&mac->evp_ctx, m, NULL);
 147                 break;
 148         case SSH_UMAC:
 149                 put_u64(nonce, seqno);
 150                 umac_update(mac->umac_ctx, data, datalen);
 151                 umac_final(mac->umac_ctx, m, nonce);
 152                 break;
 153         default:
 154                 fatal("mac_compute: unknown MAC type");
 155         }
 156         return (m);
 157 }
 158
 159 void
 160 mac_clear(Mac *mac)
 161 {
 162         if (mac->type == SSH_UMAC) {
 163                 if (mac->umac_ctx != NULL)
 164                         umac_delete(mac->umac_ctx);
 165         } else if (mac->evp_md != NULL)
 166                 HMAC_cleanup(&mac->evp_ctx);
 167         mac->evp_md = NULL;
 168         mac->umac_ctx = NULL;
 169 }
 170
 171 /* XXX copied from ciphers_valid */
 172 #define MAC_SEP ","
 173 int
 174 mac_valid(const char *names)
 175 {
 176         char *maclist, *cp, *p;
 177
 178         if (names == NULL || strcmp(names, "") == 0)
 179                 return (0);
 180         maclist = cp = xstrdup(names);
 181         for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
 182             (p = strsep(&cp, MAC_SEP))) {
 183                 if (mac_setup(NULL, p) < 0) {
 184                         debug("bad mac %s [%s]", p, names);
 185                         xfree(maclist);
 186                         return (0);
 187                 } else {
 188                         debug3("mac ok: %s [%s]", p, names);
 189                 }
 190         }
 191         debug3("macs ok: [%s]", names);
 192         xfree(maclist);
 193         return (1);
 194 }