crypto/openssh/mac.c

   1 /* $OpenBSD: mac.c,v 1.30 2014/04/30 19:07:48 naddy 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 <stdarg.h>
  31 #include <string.h>
  32 #include <signal.h>
  33
  34 #include "xmalloc.h"
  35 #include "log.h"
  36 #include "cipher.h"
  37 #include "buffer.h"
  38 #include "key.h"
  39 #include "kex.h"
  40 #include "mac.h"
  41 #include "misc.h"
  42
  43 #include "digest.h"
  44 #include "hmac.h"
  45 #include "umac.h"
  46
  47 #include "openbsd-compat/openssl-compat.h"
  48
  49 #define SSH_DIGEST      1       /* SSH_DIGEST_XXX */
  50 #define SSH_UMAC        2       /* UMAC (not integrated with OpenSSL) */
  51 #define SSH_UMAC128     3
  52
  53 struct macalg {
  54         char            *name;
  55         int             type;
  56         int             alg;
  57         int             truncatebits;   /* truncate digest if != 0 */
  58         int             key_len;        /* just for UMAC */
  59         int             len;            /* just for UMAC */
  60         int             etm;            /* Encrypt-then-MAC */
  61 };
  62
  63 static const struct macalg macs[] = {
  64         /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
  65         { "hmac-sha1",                          SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
  66         { "hmac-sha1-96",                       SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
  67 #ifdef HAVE_EVP_SHA256
  68         { "hmac-sha2-256",                      SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
  69         { "hmac-sha2-512",                      SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
  70 #endif
  71         { "hmac-md5",                           SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
  72         { "hmac-md5-96",                        SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
  73         { "hmac-ripemd160",                     SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 },
  74         { "hmac-ripemd160@openssh.com",         SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 },
  75         { "umac-64@openssh.com",                SSH_UMAC, 0, 0, 128, 64, 0 },
  76         { "umac-128@openssh.com",               SSH_UMAC128, 0, 0, 128, 128, 0 },
  77
  78         /* Encrypt-then-MAC variants */
  79         { "hmac-sha1-etm@openssh.com",          SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
  80         { "hmac-sha1-96-etm@openssh.com",       SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
  81 #ifdef HAVE_EVP_SHA256
  82         { "hmac-sha2-256-etm@openssh.com",      SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
  83         { "hmac-sha2-512-etm@openssh.com",      SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
  84 #endif
  85         { "hmac-md5-etm@openssh.com",           SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
  86         { "hmac-md5-96-etm@openssh.com",        SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
  87         { "hmac-ripemd160-etm@openssh.com",     SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 },
  88         { "umac-64-etm@openssh.com",            SSH_UMAC, 0, 0, 128, 64, 1 },
  89         { "umac-128-etm@openssh.com",           SSH_UMAC128, 0, 0, 128, 128, 1 },
  90
  91         { NULL,                                 0, 0, 0, 0, 0, 0 }
  92 };
  93
  94 /* Returns a list of supported MACs separated by the specified char. */
  95 char *
  96 mac_alg_list(char sep)
  97 {
  98         char *ret = NULL;
  99         size_t nlen, rlen = 0;
 100         const struct macalg *m;
 101
 102         for (m = macs; m->name != NULL; m++) {
 103                 if (ret != NULL)
 104                         ret[rlen++] = sep;
 105                 nlen = strlen(m->name);
 106                 ret = xrealloc(ret, 1, rlen + nlen + 2);
 107                 memcpy(ret + rlen, m->name, nlen + 1);
 108                 rlen += nlen;
 109         }
 110         return ret;
 111 }
 112
 113 static void
 114 mac_setup_by_alg(Mac *mac, const struct macalg *macalg)
 115 {
 116         mac->type = macalg->type;
 117         if (mac->type == SSH_DIGEST) {
 118                 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
 119                         fatal("ssh_hmac_start(alg=%d) failed", macalg->alg);
 120                 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
 121         } else {
 122                 mac->mac_len = macalg->len / 8;
 123                 mac->key_len = macalg->key_len / 8;
 124                 mac->umac_ctx = NULL;
 125         }
 126         if (macalg->truncatebits != 0)
 127                 mac->mac_len = macalg->truncatebits / 8;
 128         mac->etm = macalg->etm;
 129 }
 130
 131 int
 132 mac_setup(Mac *mac, char *name)
 133 {
 134         const struct macalg *m;
 135
 136         for (m = macs; m->name != NULL; m++) {
 137                 if (strcmp(name, m->name) != 0)
 138                         continue;
 139                 if (mac != NULL) {
 140                         mac_setup_by_alg(mac, m);
 141                         debug2("mac_setup: setup %s", name);
 142                 }
 143                 return (0);
 144         }
 145         debug2("mac_setup: unknown %s", name);
 146         return (-1);
 147 }
 148
 149 int
 150 mac_init(Mac *mac)
 151 {
 152         if (mac->key == NULL)
 153                 fatal("%s: no key", __func__);
 154         switch (mac->type) {
 155         case SSH_DIGEST:
 156                 if (mac->hmac_ctx == NULL ||
 157                     ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
 158                         return -1;
 159                 return 0;
 160         case SSH_UMAC:
 161                 mac->umac_ctx = umac_new(mac->key);
 162                 return 0;
 163         case SSH_UMAC128:
 164                 mac->umac_ctx = umac128_new(mac->key);
 165                 return 0;
 166         default:
 167                 return -1;
 168         }
 169 }
 170
 171 u_char *
 172 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
 173 {
 174         static union {
 175                 u_char m[EVP_MAX_MD_SIZE];
 176                 u_int64_t for_align;
 177         } u;
 178         u_char b[4];
 179         u_char nonce[8];
 180
 181         if (mac->mac_len > sizeof(u))
 182                 fatal("mac_compute: mac too long %u %zu",
 183                     mac->mac_len, sizeof(u));
 184
 185         switch (mac->type) {
 186         case SSH_DIGEST:
 187                 put_u32(b, seqno);
 188                 /* reset HMAC context */
 189                 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
 190                     ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
 191                     ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
 192                     ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
 193                         fatal("ssh_hmac failed");
 194                 break;
 195         case SSH_UMAC:
 196                 put_u64(nonce, seqno);
 197                 umac_update(mac->umac_ctx, data, datalen);
 198                 umac_final(mac->umac_ctx, u.m, nonce);
 199                 break;
 200         case SSH_UMAC128:
 201                 put_u64(nonce, seqno);
 202                 umac128_update(mac->umac_ctx, data, datalen);
 203                 umac128_final(mac->umac_ctx, u.m, nonce);
 204                 break;
 205         default:
 206                 fatal("mac_compute: unknown MAC type");
 207         }
 208         return (u.m);
 209 }
 210
 211 void
 212 mac_clear(Mac *mac)
 213 {
 214         if (mac->type == SSH_UMAC) {
 215                 if (mac->umac_ctx != NULL)
 216                         umac_delete(mac->umac_ctx);
 217         } else if (mac->type == SSH_UMAC128) {
 218                 if (mac->umac_ctx != NULL)
 219                         umac128_delete(mac->umac_ctx);
 220         } else if (mac->hmac_ctx != NULL)
 221                 ssh_hmac_free(mac->hmac_ctx);
 222         mac->hmac_ctx = NULL;
 223         mac->umac_ctx = NULL;
 224 }
 225
 226 /* XXX copied from ciphers_valid */
 227 #define MAC_SEP ","
 228 int
 229 mac_valid(const char *names)
 230 {
 231         char *maclist, *cp, *p;
 232
 233         if (names == NULL || strcmp(names, "") == 0)
 234                 return (0);
 235         maclist = cp = xstrdup(names);
 236         for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
 237             (p = strsep(&cp, MAC_SEP))) {
 238                 if (mac_setup(NULL, p) < 0) {
 239                         debug("bad mac %s [%s]", p, names);
 240                         free(maclist);
 241                         return (0);
 242                 }
 243         }
 244         debug3("macs ok: [%s]", names);
 245         free(maclist);
 246         return (1);
 247 }