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   1 /*
   2  *  Generic ASN.1 parsing
   3  *
   4  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
   5  *  SPDX-License-Identifier: GPL-2.0
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License along
  18  *  with this program; if not, write to the Free Software Foundation, Inc.,
  19  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  *  This file is part of mbed TLS (https://tls.mbed.org)
  22  */
  23
  24 #if !defined(MBEDTLS_CONFIG_FILE)
  25 #include "mbedtls/config.h"
  26 #else
  27 #include MBEDTLS_CONFIG_FILE
  28 #endif
  29
  30 #if defined(MBEDTLS_ASN1_PARSE_C)
  31
  32 #include "mbedtls/asn1.h"
  33 #include "mbedtls/platform_util.h"
  34
  35 #include <string.h>
  36
  37 #if defined(MBEDTLS_BIGNUM_C)
  38 #include "mbedtls/bignum.h"
  39 #endif
  40
  41 #if defined(MBEDTLS_PLATFORM_C)
  42 #include "mbedtls/platform.h"
  43 #else
  44 #include <stdlib.h>
  45 #define mbedtls_calloc    calloc
  46 #define mbedtls_free       free
  47 #endif
  48
  49 /*
  50  * ASN.1 DER decoding routines
  51  */
  52 int mbedtls_asn1_get_len( unsigned char **p,
  53                   const unsigned char *end,
  54                   size_t *len )
  55 {
  56     if( ( end - *p ) < 1 )
  57         return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
  58
  59     if( ( **p & 0x80 ) == 0 )
  60         *len = *(*p)++;
  61     else
  62     {
  63         switch( **p & 0x7F )
  64         {
  65         case 1:
  66             if( ( end - *p ) < 2 )
  67                 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
  68
  69             *len = (*p)[1];
  70             (*p) += 2;
  71             break;
  72
  73         case 2:
  74             if( ( end - *p ) < 3 )
  75                 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
  76
  77             *len = ( (size_t)(*p)[1] << 8 ) | (*p)[2];
  78             (*p) += 3;
  79             break;
  80
  81         case 3:
  82             if( ( end - *p ) < 4 )
  83                 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
  84
  85             *len = ( (size_t)(*p)[1] << 16 ) |
  86                    ( (size_t)(*p)[2] << 8  ) | (*p)[3];
  87             (*p) += 4;
  88             break;
  89
  90         case 4:
  91             if( ( end - *p ) < 5 )
  92                 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
  93
  94             *len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) |
  95                    ( (size_t)(*p)[3] << 8  ) |           (*p)[4];
  96             (*p) += 5;
  97             break;
  98
  99         default:
 100             return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
 101         }
 102     }
 103
 104     if( *len > (size_t) ( end - *p ) )
 105         return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
 106
 107     return( 0 );
 108 }
 109
 110 int mbedtls_asn1_get_tag( unsigned char **p,
 111                   const unsigned char *end,
 112                   size_t *len, int tag )
 113 {
 114     if( ( end - *p ) < 1 )
 115         return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
 116
 117     if( **p != tag )
 118         return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
 119
 120     (*p)++;
 121
 122     return( mbedtls_asn1_get_len( p, end, len ) );
 123 }
 124
 125 int mbedtls_asn1_get_bool( unsigned char **p,
 126                    const unsigned char *end,
 127                    int *val )
 128 {
 129     int ret;
 130     size_t len;
 131
 132     if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 )
 133         return( ret );
 134
 135     if( len != 1 )
 136         return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
 137
 138     *val = ( **p != 0 ) ? 1 : 0;
 139     (*p)++;
 140
 141     return( 0 );
 142 }
 143
 144 int mbedtls_asn1_get_int( unsigned char **p,
 145                   const unsigned char *end,
 146                   int *val )
 147 {
 148     int ret;
 149     size_t len;
 150
 151     if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
 152         return( ret );
 153
 154     if( len == 0 || len > sizeof( int ) || ( **p & 0x80 ) != 0 )
 155         return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
 156
 157     *val = 0;
 158
 159     while( len-- > 0 )
 160     {
 161         *val = ( *val << 8 ) | **p;
 162         (*p)++;
 163     }
 164
 165     return( 0 );
 166 }
 167
 168 #if defined(MBEDTLS_BIGNUM_C)
 169 int mbedtls_asn1_get_mpi( unsigned char **p,
 170                   const unsigned char *end,
 171                   mbedtls_mpi *X )
 172 {
 173     int ret;
 174     size_t len;
 175
 176     if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
 177         return( ret );
 178
 179     ret = mbedtls_mpi_read_binary( X, *p, len );
 180
 181     *p += len;
 182
 183     return( ret );
 184 }
 185 #endif /* MBEDTLS_BIGNUM_C */
 186
 187 int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
 188                         mbedtls_asn1_bitstring *bs)
 189 {
 190     int ret;
 191
 192     /* Certificate type is a single byte bitstring */
 193     if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
 194         return( ret );
 195
 196     /* Check length, subtract one for actual bit string length */
 197     if( bs->len < 1 )
 198         return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
 199     bs->len -= 1;
 200
 201     /* Get number of unused bits, ensure unused bits <= 7 */
 202     bs->unused_bits = **p;
 203     if( bs->unused_bits > 7 )
 204         return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
 205     (*p)++;
 206
 207     /* Get actual bitstring */
 208     bs->p = *p;
 209     *p += bs->len;
 210
 211     if( *p != end )
 212         return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
 213
 214     return( 0 );
 215 }
 216
 217 /*
 218  * Get a bit string without unused bits
 219  */
 220 int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
 221                              size_t *len )
 222 {
 223     int ret;
 224
 225     if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
 226         return( ret );
 227
 228     if( (*len)-- < 2 || *(*p)++ != 0 )
 229         return( MBEDTLS_ERR_ASN1_INVALID_DATA );
 230
 231     return( 0 );
 232 }
 233
 234
 235
 236 /*
 237  *  Parses and splits an ASN.1 "SEQUENCE OF <tag>"
 238  */
 239 int mbedtls_asn1_get_sequence_of( unsigned char **p,
 240                           const unsigned char *end,
 241                           mbedtls_asn1_sequence *cur,
 242                           int tag)
 243 {
 244     int ret;
 245     size_t len;
 246     mbedtls_asn1_buf *buf;
 247
 248     /* Get main sequence tag */
 249     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
 250             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
 251         return( ret );
 252
 253     if( *p + len != end )
 254         return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
 255
 256     while( *p < end )
 257     {
 258         buf = &(cur->buf);
 259         buf->tag = **p;
 260
 261         if( ( ret = mbedtls_asn1_get_tag( p, end, &buf->len, tag ) ) != 0 )
 262             return( ret );
 263
 264         buf->p = *p;
 265         *p += buf->len;
 266
 267         /* Allocate and assign next pointer */
 268         if( *p < end )
 269         {
 270             cur->next = (mbedtls_asn1_sequence*)mbedtls_calloc( 1,
 271                                             sizeof( mbedtls_asn1_sequence ) );
 272
 273             if( cur->next == NULL )
 274                 return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
 275
 276             cur = cur->next;
 277         }
 278     }
 279
 280     /* Set final sequence entry's next pointer to NULL */
 281     cur->next = NULL;
 282
 283     if( *p != end )
 284         return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
 285
 286     return( 0 );
 287 }
 288
 289 int mbedtls_asn1_get_alg( unsigned char **p,
 290                   const unsigned char *end,
 291                   mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params )
 292 {
 293     int ret;
 294     size_t len;
 295
 296     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
 297             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
 298         return( ret );
 299
 300     if( ( end - *p ) < 1 )
 301         return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
 302
 303     alg->tag = **p;
 304     end = *p + len;
 305
 306     if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 )
 307         return( ret );
 308
 309     alg->p = *p;
 310     *p += alg->len;
 311
 312     if( *p == end )
 313     {
 314         mbedtls_platform_zeroize( params, sizeof(mbedtls_asn1_buf) );
 315         return( 0 );
 316     }
 317
 318     params->tag = **p;
 319     (*p)++;
 320
 321     if( ( ret = mbedtls_asn1_get_len( p, end, &params->len ) ) != 0 )
 322         return( ret );
 323
 324     params->p = *p;
 325     *p += params->len;
 326
 327     if( *p != end )
 328         return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
 329
 330     return( 0 );
 331 }
 332
 333 int mbedtls_asn1_get_alg_null( unsigned char **p,
 334                        const unsigned char *end,
 335                        mbedtls_asn1_buf *alg )
 336 {
 337     int ret;
 338     mbedtls_asn1_buf params;
 339
 340     memset( &params, 0, sizeof(mbedtls_asn1_buf) );
 341
 342     if( ( ret = mbedtls_asn1_get_alg( p, end, alg, &params ) ) != 0 )
 343         return( ret );
 344
 345     if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 )
 346         return( MBEDTLS_ERR_ASN1_INVALID_DATA );
 347
 348     return( 0 );
 349 }
 350
 351 void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur )
 352 {
 353     if( cur == NULL )
 354         return;
 355
 356     mbedtls_free( cur->oid.p );
 357     mbedtls_free( cur->val.p );
 358
 359     mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
 360 }
 361
 362 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
 363 {
 364     mbedtls_asn1_named_data *cur;
 365
 366     while( ( cur = *head ) != NULL )
 367     {
 368         *head = cur->next;
 369         mbedtls_asn1_free_named_data( cur );
 370         mbedtls_free( cur );
 371     }
 372 }
 373
 374 mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
 375                                        const char *oid, size_t len )
 376 {
 377     while( list != NULL )
 378     {
 379         if( list->oid.len == len &&
 380             memcmp( list->oid.p, oid, len ) == 0 )
 381         {
 382             break;
 383         }
 384
 385         list = list->next;
 386     }
 387
 388     return( list );
 389 }
 390
 391 #endif /* MBEDTLS_ASN1_PARSE_C */