asn1write.c

00001 /*
00002  * ASN.1 buffer writing functionality
00003  *
00004  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
00005  *  SPDX-License-Identifier: Apache-2.0
00006  *
00007  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
00008  *  not use this file except in compliance with the License.
00009  *  You may obtain a copy of the License at
00010  *
00011  *  http://www.apache.org/licenses/LICENSE-2.0
00012  *
00013  *  Unless required by applicable law or agreed to in writing, software
00014  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
00015  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00016  *  See the License for the specific language governing permissions and
00017  *  limitations under the License.
00018  *
00019  *  This file is part of mbed TLS (https://tls.mbed.org)
00020  */
00021 
00022 #if !defined(MBEDTLS_CONFIG_FILE)
00023 #include "mbedtls/config.h"
00024 #else
00025 #include MBEDTLS_CONFIG_FILE
00026 #endif
00027 
00028 #if defined(MBEDTLS_ASN1_WRITE_C)
00029 
00030 #include "mbedtls/asn1write.h"
00031 
00032 #include <string.h>
00033 
00034 #if defined(MBEDTLS_PLATFORM_C)
00035 #include "mbedtls/platform.h"
00036 #else
00037 #include <stdlib.h>
00038 #define mbedtls_calloc    calloc
00039 #define mbedtls_free       free
00040 #endif
00041 
00042 int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
00043 {
00044     if( len < 0x80 )
00045     {
00046         if( *p - start < 1 )
00047             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00048 
00049         *--(*p) = (unsigned char) len;
00050         return( 1 );
00051     }
00052 
00053     if( len <= 0xFF )
00054     {
00055         if( *p - start < 2 )
00056             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00057 
00058         *--(*p) = (unsigned char) len;
00059         *--(*p) = 0x81;
00060         return( 2 );
00061     }
00062 
00063     if( len <= 0xFFFF )
00064     {
00065         if( *p - start < 3 )
00066             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00067 
00068         *--(*p) = ( len       ) & 0xFF;
00069         *--(*p) = ( len >>  8 ) & 0xFF;
00070         *--(*p) = 0x82;
00071         return( 3 );
00072     }
00073 
00074     if( len <= 0xFFFFFF )
00075     {
00076         if( *p - start < 4 )
00077             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00078 
00079         *--(*p) = ( len       ) & 0xFF;
00080         *--(*p) = ( len >>  8 ) & 0xFF;
00081         *--(*p) = ( len >> 16 ) & 0xFF;
00082         *--(*p) = 0x83;
00083         return( 4 );
00084     }
00085 
00086 #if SIZE_MAX > 0xFFFFFFFF
00087     if( len <= 0xFFFFFFFF )
00088 #endif
00089     {
00090         if( *p - start < 5 )
00091             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00092 
00093         *--(*p) = ( len       ) & 0xFF;
00094         *--(*p) = ( len >>  8 ) & 0xFF;
00095         *--(*p) = ( len >> 16 ) & 0xFF;
00096         *--(*p) = ( len >> 24 ) & 0xFF;
00097         *--(*p) = 0x84;
00098         return( 5 );
00099     }
00100 
00101 #if SIZE_MAX > 0xFFFFFFFF
00102     return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
00103 #endif
00104 }
00105 
00106 int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
00107 {
00108     if( *p - start < 1 )
00109         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00110 
00111     *--(*p) = tag;
00112 
00113     return( 1 );
00114 }
00115 
00116 int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
00117                            const unsigned char *buf, size_t size )
00118 {
00119     size_t len = 0;
00120 
00121     if( *p < start || (size_t)( *p - start ) < size )
00122         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00123 
00124     len = size;
00125     (*p) -= len;
00126     memcpy( *p, buf, len );
00127 
00128     return( (int) len );
00129 }
00130 
00131 #if defined(MBEDTLS_BIGNUM_C)
00132 int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
00133 {
00134     int ret;
00135     size_t len = 0;
00136 
00137     // Write the MPI
00138     //
00139     len = mbedtls_mpi_size( X );
00140 
00141     if( *p < start || (size_t)( *p - start ) < len )
00142         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00143 
00144     (*p) -= len;
00145     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
00146 
00147     // DER format assumes 2s complement for numbers, so the leftmost bit
00148     // should be 0 for positive numbers and 1 for negative numbers.
00149     //
00150     if( X->s  ==1 && **p & 0x80 )
00151     {
00152         if( *p - start < 1 )
00153             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00154 
00155         *--(*p) = 0x00;
00156         len += 1;
00157     }
00158 
00159     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00160     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
00161 
00162     ret = (int) len;
00163 
00164 cleanup:
00165     return( ret );
00166 }
00167 #endif /* MBEDTLS_BIGNUM_C */
00168 
00169 int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
00170 {
00171     int ret;
00172     size_t len = 0;
00173 
00174     // Write NULL
00175     //
00176     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
00177     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
00178 
00179     return( (int) len );
00180 }
00181 
00182 int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
00183                     const char *oid, size_t oid_len )
00184 {
00185     int ret;
00186     size_t len = 0;
00187 
00188     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
00189                                   (const unsigned char *) oid, oid_len ) );
00190     MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
00191     MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
00192 
00193     return( (int) len );
00194 }
00195 
00196 int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
00197                                      const char *oid, size_t oid_len,
00198                                      size_t par_len )
00199 {
00200     int ret;
00201     size_t len = 0;
00202 
00203     if( par_len == 0 )
00204         MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
00205     else
00206         len += par_len;
00207 
00208     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
00209 
00210     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00211     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
00212                                        MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
00213 
00214     return( (int) len );
00215 }
00216 
00217 int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
00218 {
00219     int ret;
00220     size_t len = 0;
00221 
00222     if( *p - start < 1 )
00223         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00224 
00225     *--(*p) = (boolean) ? 255 : 0;
00226     len++;
00227 
00228     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00229     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
00230 
00231     return( (int) len );
00232 }
00233 
00234 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
00235 {
00236     int ret;
00237     size_t len = 0;
00238 
00239     if( *p - start < 1 )
00240         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00241 
00242     len += 1;
00243     *--(*p) = val;
00244 
00245     if( val > 0 && **p & 0x80 )
00246     {
00247         if( *p - start < 1 )
00248             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00249 
00250         *--(*p) = 0x00;
00251         len += 1;
00252     }
00253 
00254     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00255     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
00256 
00257     return( (int) len );
00258 }
00259 
00260 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
00261                                  const char *text, size_t text_len )
00262 {
00263     int ret;
00264     size_t len = 0;
00265 
00266     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
00267                   (const unsigned char *) text, text_len ) );
00268 
00269     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00270     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_PRINTABLE_STRING ) );
00271 
00272     return( (int) len );
00273 }
00274 
00275 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
00276                            const char *text, size_t text_len )
00277 {
00278     int ret;
00279     size_t len = 0;
00280 
00281     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
00282                   (const unsigned char *) text, text_len ) );
00283 
00284     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00285     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );
00286 
00287     return( (int) len );
00288 }
00289 
00290 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
00291                           const unsigned char *buf, size_t bits )
00292 {
00293     int ret;
00294     size_t len = 0, size;
00295 
00296     size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
00297 
00298     // Calculate byte length
00299     //
00300     if( *p < start || (size_t)( *p - start ) < size + 1 )
00301         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
00302 
00303     len = size + 1;
00304     (*p) -= size;
00305     memcpy( *p, buf, size );
00306 
00307     // Write unused bits
00308     //
00309     *--(*p) = (unsigned char) (size * 8 - bits);
00310 
00311     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00312     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
00313 
00314     return( (int) len );
00315 }
00316 
00317 int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
00318                              const unsigned char *buf, size_t size )
00319 {
00320     int ret;
00321     size_t len = 0;
00322 
00323     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
00324 
00325     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
00326     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
00327 
00328     return( (int) len );
00329 }
00330 
00331 mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( mbedtls_asn1_named_data **head,
00332                                         const char *oid, size_t oid_len,
00333                                         const unsigned char *val,
00334                                         size_t val_len )
00335 {
00336     mbedtls_asn1_named_data *cur;
00337 
00338     if( ( cur = mbedtls_asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
00339     {
00340         // Add new entry if not present yet based on OID
00341         //
00342         cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
00343                                             sizeof(mbedtls_asn1_named_data) );
00344         if( cur == NULL )
00345             return( NULL );
00346 
00347         cur->oid.len = oid_len;
00348         cur->oid.p = mbedtls_calloc( 1, oid_len );
00349         if( cur->oid.p == NULL )
00350         {
00351             mbedtls_free( cur );
00352             return( NULL );
00353         }
00354 
00355         memcpy( cur->oid.p, oid, oid_len );
00356 
00357         cur->val.len = val_len;
00358         cur->val.p = mbedtls_calloc( 1, val_len );
00359         if( cur->val.p == NULL )
00360         {
00361             mbedtls_free( cur->oid.p );
00362             mbedtls_free( cur );
00363             return( NULL );
00364         }
00365 
00366         cur->next = *head;
00367         *head = cur;
00368     }
00369     else if( cur->val.len < val_len )
00370     {
00371         /*
00372          * Enlarge existing value buffer if needed
00373          * Preserve old data until the allocation succeeded, to leave list in
00374          * a consistent state in case allocation fails.
00375          */
00376         void *p = mbedtls_calloc( 1, val_len );
00377         if( p == NULL )
00378             return( NULL );
00379 
00380         mbedtls_free( cur->val.p );
00381         cur->val.p = p;
00382         cur->val.len = val_len;
00383     }
00384 
00385     if( val != NULL )
00386         memcpy( cur->val.p, val, val_len );
00387 
00388     return( cur );
00389 }
00390 #endif /* MBEDTLS_ASN1_WRITE_C */