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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 */
  392.