cbc_mac.c

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    1 /*
    2  * Copyright (c) 2018-2019 iXsystems Inc.  All rights reserved.
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. Redistributions in binary form must reproduce the above copyright
   10  *    notice, this list of conditions and the following disclaimer in the
   11  *    documentation and/or other materials provided with the distribution.
   12  *
   13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   23  */
   24 
   25 #include <sys/cdefs.h>
   26 __FBSDID("$FreeBSD$");
   27 
   28 #include <sys/types.h>
   29 #include <sys/systm.h>
   30 #include <sys/param.h>
   31 #include <sys/endian.h>
   32 #include <opencrypto/cbc_mac.h>
   33 #include <opencrypto/xform_auth.h>
   34 
   35 /*
   36  * Given two CCM_CBC_BLOCK_LEN blocks, xor
   37  * them into dst, and then encrypt dst.
   38  */
   39 static void
   40 xor_and_encrypt(struct aes_cbc_mac_ctx *ctx,
   41                 const uint8_t *src, uint8_t *dst)
   42 {
   43         const uint64_t *b1;
   44         uint64_t *b2;
   45         uint64_t temp_block[CCM_CBC_BLOCK_LEN/sizeof(uint64_t)];
   46 
   47         b1 = (const uint64_t*)src;
   48         b2 = (uint64_t*)dst;
   49 
   50         for (size_t count = 0;
   51              count < CCM_CBC_BLOCK_LEN/sizeof(uint64_t);
   52              count++) {
   53                 temp_block[count] = b1[count] ^ b2[count];
   54         }
   55         rijndaelEncrypt(ctx->keysched, ctx->rounds, (void*)temp_block, dst);
   56 }
   57 
   58 void
   59 AES_CBC_MAC_Init(struct aes_cbc_mac_ctx *ctx)
   60 {
   61         bzero(ctx, sizeof(*ctx));
   62 }
   63 
   64 void
   65 AES_CBC_MAC_Setkey(struct aes_cbc_mac_ctx *ctx, const uint8_t *key, uint16_t klen)
   66 {
   67         ctx->rounds = rijndaelKeySetupEnc(ctx->keysched, key, klen * 8);
   68 }
   69 
   70 /*
   71  * This is called to set the nonce, aka IV.
   72  * Before this call, the authDataLength and cryptDataLength fields
   73  * MUST have been set.  Sadly, there's no way to return an error.
   74  *
   75  * The CBC-MAC algorithm requires that the first block contain the
   76  * nonce, as well as information about the sizes and lengths involved.
   77  */
   78 void
   79 AES_CBC_MAC_Reinit(struct aes_cbc_mac_ctx *ctx, const uint8_t *nonce, uint16_t nonceLen)
   80 {
   81         uint8_t b0[CCM_CBC_BLOCK_LEN];
   82         uint8_t *bp = b0, flags = 0;
   83         uint8_t L = 0;
   84         uint64_t dataLength = ctx->cryptDataLength;
   85 
   86         KASSERT(nonceLen >= 7 && nonceLen <= 13,
   87             ("nonceLen must be between 7 and 13 bytes"));
   88 
   89         ctx->nonce = nonce;
   90         ctx->nonceLength = nonceLen;
   91         
   92         ctx->authDataCount = 0;
   93         ctx->blockIndex = 0;
   94         explicit_bzero(ctx->staging_block, sizeof(ctx->staging_block));
   95         
   96         /*
   97          * Need to determine the L field value.  This is the number of
   98          * bytes needed to specify the length of the message; the length
   99          * is whatever is left in the 16 bytes after specifying flags and
  100          * the nonce.
  101          */
  102         L = 15 - nonceLen;
  103         
  104         flags = ((ctx->authDataLength > 0) << 6) +
  105             (((AES_CBC_MAC_HASH_LEN - 2) / 2) << 3) +
  106             L - 1;
  107         /*
  108          * Now we need to set up the first block, which has flags, nonce,
  109          * and the message length.
  110          */
  111         b0[0] = flags;
  112         bcopy(nonce, b0 + 1, nonceLen);
  113         bp = b0 + 1 + nonceLen;
  114 
  115         /* Need to copy L' [aka L-1] bytes of cryptDataLength */
  116         for (uint8_t *dst = b0 + sizeof(b0) - 1; dst >= bp; dst--) {
  117                 *dst = dataLength;
  118                 dataLength >>= 8;
  119         }
  120         /* Now need to encrypt b0 */
  121         rijndaelEncrypt(ctx->keysched, ctx->rounds, b0, ctx->block);
  122         /* If there is auth data, we need to set up the staging block */
  123         if (ctx->authDataLength) {
  124                 size_t addLength;
  125                 if (ctx->authDataLength < ((1<<16) - (1<<8))) {
  126                         uint16_t sizeVal = htobe16(ctx->authDataLength);
  127                         bcopy(&sizeVal, ctx->staging_block, sizeof(sizeVal));
  128                         addLength = sizeof(sizeVal);
  129                 } else if (ctx->authDataLength < (1ULL<<32)) {
  130                         uint32_t sizeVal = htobe32(ctx->authDataLength);
  131                         ctx->staging_block[0] = 0xff;
  132                         ctx->staging_block[1] = 0xfe;
  133                         bcopy(&sizeVal, ctx->staging_block+2, sizeof(sizeVal));
  134                         addLength = 2 + sizeof(sizeVal);
  135                 } else {
  136                         uint64_t sizeVal = htobe64(ctx->authDataLength);
  137                         ctx->staging_block[0] = 0xff;
  138                         ctx->staging_block[1] = 0xff;
  139                         bcopy(&sizeVal, ctx->staging_block+2, sizeof(sizeVal));
  140                         addLength = 2 + sizeof(sizeVal);
  141                 }
  142                 ctx->blockIndex = addLength;
  143                 /*
  144                  * The length descriptor goes into the AAD buffer, so we
  145                  * need to account for it.
  146                  */
  147                 ctx->authDataLength += addLength;
  148                 ctx->authDataCount = addLength;
  149         }
  150 }
  151 
  152 int
  153 AES_CBC_MAC_Update(struct aes_cbc_mac_ctx *ctx, const uint8_t *data,
  154     uint16_t length)
  155 {
  156         size_t copy_amt;
  157         
  158         /*
  159          * This will be called in one of two phases:
  160          * (1)  Applying authentication data, or
  161          * (2)  Applying the payload data.
  162          *
  163          * Because CBC-MAC puts the authentication data size before the
  164          * data, subsequent calls won't be block-size-aligned.  Which
  165          * complicates things a fair bit.
  166          *
  167          * The payload data doesn't have that problem.
  168          */
  169                                 
  170         if (ctx->authDataCount < ctx->authDataLength) {
  171                 /*
  172                  * We need to process data as authentication data.
  173                  * Since we may be out of sync, we may also need
  174                  * to pad out the staging block.
  175                  */
  176                 const uint8_t *ptr = data;
  177                 while (length > 0) {
  178 
  179                         copy_amt = MIN(length,
  180                             sizeof(ctx->staging_block) - ctx->blockIndex);
  181 
  182                         bcopy(ptr, ctx->staging_block + ctx->blockIndex,
  183                             copy_amt);
  184                         ptr += copy_amt;
  185                         length -= copy_amt;
  186                         ctx->authDataCount += copy_amt;
  187                         ctx->blockIndex += copy_amt;
  188                         ctx->blockIndex %= sizeof(ctx->staging_block);
  189 
  190                         if (ctx->blockIndex == 0 ||
  191                             ctx->authDataCount == ctx->authDataLength) {
  192                                 /*
  193                                  * We're done with this block, so we
  194                                  * xor staging_block with block, and then
  195                                  * encrypt it.
  196                                  */
  197                                 xor_and_encrypt(ctx, ctx->staging_block, ctx->block);
  198                                 bzero(ctx->staging_block, sizeof(ctx->staging_block));
  199                                 ctx->blockIndex = 0;
  200                                 if (ctx->authDataCount >= ctx->authDataLength)
  201                                         break;
  202                         }
  203                 }
  204                 /*
  205                  * We'd like to be able to check length == 0 and return
  206                  * here, but the way OCF calls us, length is always
  207                  * blksize (16, in this case).  So we have to count on
  208                  * the fact that OCF calls us separately for the AAD and
  209                  * for the real data.
  210                  */
  211                 return (0);
  212         }
  213         /*
  214          * If we're here, then we're encoding payload data.
  215          * This is marginally easier, except that _Update can
  216          * be called with non-aligned update lengths. As a result,
  217          * we still need to use the staging block.
  218          */
  219         KASSERT((length + ctx->cryptDataCount) <= ctx->cryptDataLength,
  220             ("More encryption data than allowed"));
  221 
  222         while (length) {
  223                 uint8_t *ptr;
  224                 
  225                 copy_amt = MIN(sizeof(ctx->staging_block) - ctx->blockIndex,
  226                     length);
  227                 ptr = ctx->staging_block + ctx->blockIndex;
  228                 bcopy(data, ptr, copy_amt);
  229                 data += copy_amt;
  230                 ctx->blockIndex += copy_amt;
  231                 ctx->cryptDataCount += copy_amt;
  232                 length -= copy_amt;
  233                 if (ctx->blockIndex == sizeof(ctx->staging_block)) {
  234                         /* We've got a full block */
  235                         xor_and_encrypt(ctx, ctx->staging_block, ctx->block);
  236                         ctx->blockIndex = 0;
  237                         bzero(ctx->staging_block, sizeof(ctx->staging_block));
  238                 }
  239         }
  240         return (0);
  241 }
  242 
  243 void
  244 AES_CBC_MAC_Final(uint8_t *buf, struct aes_cbc_mac_ctx *ctx)
  245 {
  246         uint8_t s0[CCM_CBC_BLOCK_LEN];
  247         
  248         /*
  249          * We first need to check to see if we've got any data
  250          * left over to encrypt.
  251          */
  252         if (ctx->blockIndex != 0) {
  253                 xor_and_encrypt(ctx, ctx->staging_block, ctx->block);
  254                 ctx->cryptDataCount += ctx->blockIndex;
  255                 ctx->blockIndex = 0;
  256                 explicit_bzero(ctx->staging_block, sizeof(ctx->staging_block));
  257         }
  258         bzero(s0, sizeof(s0));
  259         s0[0] = (15 - ctx->nonceLength) - 1;
  260         bcopy(ctx->nonce, s0 + 1, ctx->nonceLength);
  261         rijndaelEncrypt(ctx->keysched, ctx->rounds, s0, s0);
  262         for (size_t indx = 0; indx < AES_CBC_MAC_HASH_LEN; indx++)
  263                 buf[indx] = ctx->block[indx] ^ s0[indx];
  264         explicit_bzero(s0, sizeof(s0));
  265 }
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FreeBSD/Linux Kernel Cross Reference sys/opencrypto/cbc_mac.c

FreeBSD/Linux Kernel Cross Reference
sys/opencrypto/cbc_mac.c
