1 /* 2 * ASN.1 buffer writing functionality 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 * 7 * This file is provided under the Apache License 2.0, or the 8 * GNU General Public License v2.0 or later. 9 * 10 * ********** 11 * Apache License 2.0: 12 * 13 * Licensed under the Apache License, Version 2.0 (the "License"); you may 14 * not use this file except in compliance with the License. 15 * You may obtain a copy of the License at 16 * 17 * http://www.apache.org/licenses/LICENSE-2.0 18 * 19 * Unless required by applicable law or agreed to in writing, software 20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 22 * See the License for the specific language governing permissions and 23 * limitations under the License. 24 * 25 * ********** 26 * 27 * ********** 28 * GNU General Public License v2.0 or later: 29 * 30 * This program is free software; you can redistribute it and/or modify 31 * it under the terms of the GNU General Public License as published by 32 * the Free Software Foundation; either version 2 of the License, or 33 * (at your option) any later version. 34 * 35 * This program is distributed in the hope that it will be useful, 36 * but WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 38 * GNU General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 43 * 44 * ********** 45 */ 46 47 #if !defined(MBEDTLS_CONFIG_FILE) 48 #include "mbedtls/config.h" 49 #else 50 #include MBEDTLS_CONFIG_FILE 51 #endif 52 53 #if defined(MBEDTLS_ASN1_WRITE_C) 54 55 #include "mbedtls/asn1write.h" 56 57 #include <string.h> 58 59 #if defined(MBEDTLS_PLATFORM_C) 60 #include "mbedtls/platform.h" 61 #else 62 #include <stdlib.h> 63 #define mbedtls_calloc calloc 64 #define mbedtls_free free 65 #endif 66 67 int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len ) 68 { 69 if( len < 0x80 ) 70 { 71 if( *p - start < 1 ) 72 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 73 74 *--(*p) = (unsigned char) len; 75 return( 1 ); 76 } 77 78 if( len <= 0xFF ) 79 { 80 if( *p - start < 2 ) 81 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 82 83 *--(*p) = (unsigned char) len; 84 *--(*p) = 0x81; 85 return( 2 ); 86 } 87 88 if( len <= 0xFFFF ) 89 { 90 if( *p - start < 3 ) 91 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 92 93 *--(*p) = ( len ) & 0xFF; 94 *--(*p) = ( len >> 8 ) & 0xFF; 95 *--(*p) = 0x82; 96 return( 3 ); 97 } 98 99 if( len <= 0xFFFFFF ) 100 { 101 if( *p - start < 4 ) 102 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 103 104 *--(*p) = ( len ) & 0xFF; 105 *--(*p) = ( len >> 8 ) & 0xFF; 106 *--(*p) = ( len >> 16 ) & 0xFF; 107 *--(*p) = 0x83; 108 return( 4 ); 109 } 110 111 #if SIZE_MAX > 0xFFFFFFFF 112 if( len <= 0xFFFFFFFF ) 113 #endif 114 { 115 if( *p - start < 5 ) 116 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 117 118 *--(*p) = ( len ) & 0xFF; 119 *--(*p) = ( len >> 8 ) & 0xFF; 120 *--(*p) = ( len >> 16 ) & 0xFF; 121 *--(*p) = ( len >> 24 ) & 0xFF; 122 *--(*p) = 0x84; 123 return( 5 ); 124 } 125 126 #if SIZE_MAX > 0xFFFFFFFF 127 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 128 #endif 129 } 130 131 int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag ) 132 { 133 if( *p - start < 1 ) 134 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 135 136 *--(*p) = tag; 137 138 return( 1 ); 139 } 140 141 int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start, 142 const unsigned char *buf, size_t size ) 143 { 144 size_t len = 0; 145 146 if( *p < start || (size_t)( *p - start ) < size ) 147 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 148 149 len = size; 150 (*p) -= len; 151 memcpy( *p, buf, len ); 152 153 return( (int) len ); 154 } 155 156 #if defined(MBEDTLS_BIGNUM_C) 157 int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X ) 158 { 159 int ret; 160 size_t len = 0; 161 162 // Write the MPI 163 // 164 len = mbedtls_mpi_size( X ); 165 166 if( *p < start || (size_t)( *p - start ) < len ) 167 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 168 169 (*p) -= len; 170 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) ); 171 172 // DER format assumes 2s complement for numbers, so the leftmost bit 173 // should be 0 for positive numbers and 1 for negative numbers. 174 // 175 if( X->s ==1 && **p & 0x80 ) 176 { 177 if( *p - start < 1 ) 178 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 179 180 *--(*p) = 0x00; 181 len += 1; 182 } 183 184 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 185 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) ); 186 187 ret = (int) len; 188 189 cleanup: 190 return( ret ); 191 } 192 #endif /* MBEDTLS_BIGNUM_C */ 193 194 int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start ) 195 { 196 int ret; 197 size_t len = 0; 198 199 // Write NULL 200 // 201 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) ); 202 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) ); 203 204 return( (int) len ); 205 } 206 207 int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start, 208 const char *oid, size_t oid_len ) 209 { 210 int ret; 211 size_t len = 0; 212 213 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, 214 (const unsigned char *) oid, oid_len ) ); 215 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) ); 216 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) ); 217 218 return( (int) len ); 219 } 220 221 int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start, 222 const char *oid, size_t oid_len, 223 size_t par_len ) 224 { 225 int ret; 226 size_t len = 0; 227 228 if( par_len == 0 ) 229 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) ); 230 else 231 len += par_len; 232 233 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) ); 234 235 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 236 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, 237 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); 238 239 return( (int) len ); 240 } 241 242 int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean ) 243 { 244 int ret; 245 size_t len = 0; 246 247 if( *p - start < 1 ) 248 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 249 250 *--(*p) = (boolean) ? 255 : 0; 251 len++; 252 253 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 254 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) ); 255 256 return( (int) len ); 257 } 258 259 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val ) 260 { 261 int ret; 262 size_t len = 0; 263 264 if( *p - start < 1 ) 265 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 266 267 len += 1; 268 *--(*p) = val; 269 270 if( val > 0 && **p & 0x80 ) 271 { 272 if( *p - start < 1 ) 273 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 274 275 *--(*p) = 0x00; 276 len += 1; 277 } 278 279 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 280 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) ); 281 282 return( (int) len ); 283 } 284 285 int mbedtls_asn1_write_tagged_string( unsigned char **p, unsigned char *start, int tag, 286 const char *text, size_t text_len ) 287 { 288 int ret; 289 size_t len = 0; 290 291 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, 292 (const unsigned char *) text, text_len ) ); 293 294 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 295 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) ); 296 297 return( (int) len ); 298 } 299 300 int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start, 301 const char *text, size_t text_len ) 302 { 303 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len) ); 304 } 305 306 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start, 307 const char *text, size_t text_len ) 308 { 309 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, text_len) ); 310 } 311 312 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start, 313 const char *text, size_t text_len ) 314 { 315 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len) ); 316 } 317 318 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start, 319 const unsigned char *buf, size_t bits ) 320 { 321 int ret; 322 size_t len = 0; 323 size_t unused_bits, byte_len; 324 325 byte_len = ( bits + 7 ) / 8; 326 unused_bits = ( byte_len * 8 ) - bits; 327 328 if( *p < start || (size_t)( *p - start ) < byte_len + 1 ) 329 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 330 331 len = byte_len + 1; 332 333 /* Write the bitstring. Ensure the unused bits are zeroed */ 334 if( byte_len > 0 ) 335 { 336 byte_len--; 337 *--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 ); 338 ( *p ) -= byte_len; 339 memcpy( *p, buf, byte_len ); 340 } 341 342 /* Write unused bits */ 343 *--( *p ) = (unsigned char)unused_bits; 344 345 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 346 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) ); 347 348 return( (int) len ); 349 } 350 351 int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start, 352 const unsigned char *buf, size_t size ) 353 { 354 int ret; 355 size_t len = 0; 356 357 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) ); 358 359 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 360 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) ); 361 362 return( (int) len ); 363 } 364 365 366 /* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(), 367 * which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */ 368 static mbedtls_asn1_named_data *asn1_find_named_data( 369 mbedtls_asn1_named_data *list, 370 const char *oid, size_t len ) 371 { 372 while( list != NULL ) 373 { 374 if( list->oid.len == len && 375 memcmp( list->oid.p, oid, len ) == 0 ) 376 { 377 break; 378 } 379 380 list = list->next; 381 } 382 383 return( list ); 384 } 385 386 mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( 387 mbedtls_asn1_named_data **head, 388 const char *oid, size_t oid_len, 389 const unsigned char *val, 390 size_t val_len ) 391 { 392 mbedtls_asn1_named_data *cur; 393 394 if( ( cur = asn1_find_named_data( *head, oid, oid_len ) ) == NULL ) 395 { 396 // Add new entry if not present yet based on OID 397 // 398 cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1, 399 sizeof(mbedtls_asn1_named_data) ); 400 if( cur == NULL ) 401 return( NULL ); 402 403 cur->oid.len = oid_len; 404 cur->oid.p = mbedtls_calloc( 1, oid_len ); 405 if( cur->oid.p == NULL ) 406 { 407 mbedtls_free( cur ); 408 return( NULL ); 409 } 410 411 memcpy( cur->oid.p, oid, oid_len ); 412 413 cur->val.len = val_len; 414 cur->val.p = mbedtls_calloc( 1, val_len ); 415 if( cur->val.p == NULL ) 416 { 417 mbedtls_free( cur->oid.p ); 418 mbedtls_free( cur ); 419 return( NULL ); 420 } 421 422 cur->next = *head; 423 *head = cur; 424 } 425 else if( cur->val.len < val_len ) 426 { 427 /* 428 * Enlarge existing value buffer if needed 429 * Preserve old data until the allocation succeeded, to leave list in 430 * a consistent state in case allocation fails. 431 */ 432 void *p = mbedtls_calloc( 1, val_len ); 433 if( p == NULL ) 434 return( NULL ); 435 436 mbedtls_free( cur->val.p ); 437 cur->val.p = p; 438 cur->val.len = val_len; 439 } 440 441 if( val != NULL ) 442 memcpy( cur->val.p, val, val_len ); 443 444 return( cur ); 445 } 446 #endif /* MBEDTLS_ASN1_WRITE_C */ 447