1 /* 2 * Generic ASN.1 parsing 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 6 * 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may 8 * not use this file except in compliance with the License. 9 * You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 #include "common.h" 21 22 #if defined(MBEDTLS_ASN1_PARSE_C) 23 24 #include "mbedtls/asn1.h" 25 #include "mbedtls/platform_util.h" 26 #include "mbedtls/error.h" 27 28 #include <string.h> 29 30 #if defined(MBEDTLS_BIGNUM_C) 31 #include "mbedtls/bignum.h" 32 #endif 33 34 #if defined(MBEDTLS_PLATFORM_C) 35 #include "mbedtls/platform.h" 36 #else 37 #include <stdlib.h> 38 #define mbedtls_calloc calloc 39 #define mbedtls_free free 40 #endif 41 42 /* 43 * ASN.1 DER decoding routines 44 */ 45 int mbedtls_asn1_get_len( unsigned char **p, 46 const unsigned char *end, 47 size_t *len ) 48 { 49 if( ( end - *p ) < 1 ) 50 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 51 52 if( ( **p & 0x80 ) == 0 ) 53 *len = *(*p)++; 54 else 55 { 56 switch( **p & 0x7F ) 57 { 58 case 1: 59 if( ( end - *p ) < 2 ) 60 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 61 62 *len = (*p)[1]; 63 (*p) += 2; 64 break; 65 66 case 2: 67 if( ( end - *p ) < 3 ) 68 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 69 70 *len = ( (size_t)(*p)[1] << 8 ) | (*p)[2]; 71 (*p) += 3; 72 break; 73 74 case 3: 75 if( ( end - *p ) < 4 ) 76 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 77 78 *len = ( (size_t)(*p)[1] << 16 ) | 79 ( (size_t)(*p)[2] << 8 ) | (*p)[3]; 80 (*p) += 4; 81 break; 82 83 case 4: 84 if( ( end - *p ) < 5 ) 85 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 86 87 *len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) | 88 ( (size_t)(*p)[3] << 8 ) | (*p)[4]; 89 (*p) += 5; 90 break; 91 92 default: 93 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 94 } 95 } 96 97 if( *len > (size_t) ( end - *p ) ) 98 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 99 100 return( 0 ); 101 } 102 103 int mbedtls_asn1_get_tag( unsigned char **p, 104 const unsigned char *end, 105 size_t *len, int tag ) 106 { 107 if( ( end - *p ) < 1 ) 108 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 109 110 if( **p != tag ) 111 return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ); 112 113 (*p)++; 114 115 return( mbedtls_asn1_get_len( p, end, len ) ); 116 } 117 118 int mbedtls_asn1_get_bool( unsigned char **p, 119 const unsigned char *end, 120 int *val ) 121 { 122 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 123 size_t len; 124 125 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 ) 126 return( ret ); 127 128 if( len != 1 ) 129 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 130 131 *val = ( **p != 0 ) ? 1 : 0; 132 (*p)++; 133 134 return( 0 ); 135 } 136 137 static int asn1_get_tagged_int( unsigned char **p, 138 const unsigned char *end, 139 int tag, int *val ) 140 { 141 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 142 size_t len; 143 144 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, tag ) ) != 0 ) 145 return( ret ); 146 147 /* 148 * len==0 is malformed (0 must be represented as 020100 for INTEGER, 149 * or 0A0100 for ENUMERATED tags 150 */ 151 if( len == 0 ) 152 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 153 /* This is a cryptography library. Reject negative integers. */ 154 if( ( **p & 0x80 ) != 0 ) 155 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 156 157 /* Skip leading zeros. */ 158 while( len > 0 && **p == 0 ) 159 { 160 ++( *p ); 161 --len; 162 } 163 164 /* Reject integers that don't fit in an int. This code assumes that 165 * the int type has no padding bit. */ 166 if( len > sizeof( int ) ) 167 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 168 if( len == sizeof( int ) && ( **p & 0x80 ) != 0 ) 169 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 170 171 *val = 0; 172 while( len-- > 0 ) 173 { 174 *val = ( *val << 8 ) | **p; 175 (*p)++; 176 } 177 178 return( 0 ); 179 } 180 181 int mbedtls_asn1_get_int( unsigned char **p, 182 const unsigned char *end, 183 int *val ) 184 { 185 return( asn1_get_tagged_int( p, end, MBEDTLS_ASN1_INTEGER, val) ); 186 } 187 188 int mbedtls_asn1_get_enum( unsigned char **p, 189 const unsigned char *end, 190 int *val ) 191 { 192 return( asn1_get_tagged_int( p, end, MBEDTLS_ASN1_ENUMERATED, val) ); 193 } 194 195 #if defined(MBEDTLS_BIGNUM_C) 196 int mbedtls_asn1_get_mpi( unsigned char **p, 197 const unsigned char *end, 198 mbedtls_mpi *X ) 199 { 200 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 201 size_t len; 202 203 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 ) 204 return( ret ); 205 206 ret = mbedtls_mpi_read_binary( X, *p, len ); 207 208 *p += len; 209 210 return( ret ); 211 } 212 #endif /* MBEDTLS_BIGNUM_C */ 213 214 int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end, 215 mbedtls_asn1_bitstring *bs) 216 { 217 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 218 219 /* Certificate type is a single byte bitstring */ 220 if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 ) 221 return( ret ); 222 223 /* Check length, subtract one for actual bit string length */ 224 if( bs->len < 1 ) 225 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 226 bs->len -= 1; 227 228 /* Get number of unused bits, ensure unused bits <= 7 */ 229 bs->unused_bits = **p; 230 if( bs->unused_bits > 7 ) 231 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); 232 (*p)++; 233 234 /* Get actual bitstring */ 235 bs->p = *p; 236 *p += bs->len; 237 238 if( *p != end ) 239 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ); 240 241 return( 0 ); 242 } 243 244 /* 245 * Traverse an ASN.1 "SEQUENCE OF <tag>" 246 * and call a callback for each entry found. 247 */ 248 int mbedtls_asn1_traverse_sequence_of( 249 unsigned char **p, 250 const unsigned char *end, 251 unsigned char tag_must_mask, unsigned char tag_must_val, 252 unsigned char tag_may_mask, unsigned char tag_may_val, 253 int (*cb)( void *ctx, int tag, 254 unsigned char *start, size_t len ), 255 void *ctx ) 256 { 257 int ret; 258 size_t len; 259 260 /* Get main sequence tag */ 261 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, 262 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) 263 { 264 return( ret ); 265 } 266 267 if( *p + len != end ) 268 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ); 269 270 while( *p < end ) 271 { 272 unsigned char const tag = *(*p)++; 273 274 if( ( tag & tag_must_mask ) != tag_must_val ) 275 return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ); 276 277 if( ( ret = mbedtls_asn1_get_len( p, end, &len ) ) != 0 ) 278 return( ret ); 279 280 if( ( tag & tag_may_mask ) == tag_may_val ) 281 { 282 if( cb != NULL ) 283 { 284 ret = cb( ctx, tag, *p, len ); 285 if( ret != 0 ) 286 return( ret ); 287 } 288 } 289 290 *p += len; 291 } 292 293 return( 0 ); 294 } 295 296 /* 297 * Get a bit string without unused bits 298 */ 299 int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end, 300 size_t *len ) 301 { 302 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 303 304 if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 ) 305 return( ret ); 306 307 if( *len == 0 ) 308 return( MBEDTLS_ERR_ASN1_INVALID_DATA ); 309 --( *len ); 310 311 if( **p != 0 ) 312 return( MBEDTLS_ERR_ASN1_INVALID_DATA ); 313 ++( *p ); 314 315 return( 0 ); 316 } 317 318 void mbedtls_asn1_sequence_free( mbedtls_asn1_sequence *seq ) 319 { 320 while( seq != NULL ) 321 { 322 mbedtls_asn1_sequence *next = seq->next; 323 mbedtls_platform_zeroize( seq, sizeof( *seq ) ); 324 mbedtls_free( seq ); 325 seq = next; 326 } 327 } 328 329 typedef struct 330 { 331 int tag; 332 mbedtls_asn1_sequence *cur; 333 } asn1_get_sequence_of_cb_ctx_t; 334 335 static int asn1_get_sequence_of_cb( void *ctx, 336 int tag, 337 unsigned char *start, 338 size_t len ) 339 { 340 asn1_get_sequence_of_cb_ctx_t *cb_ctx = 341 (asn1_get_sequence_of_cb_ctx_t *) ctx; 342 mbedtls_asn1_sequence *cur = 343 cb_ctx->cur; 344 345 if( cur->buf.p != NULL ) 346 { 347 cur->next = 348 mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) ); 349 350 if( cur->next == NULL ) 351 return( MBEDTLS_ERR_ASN1_ALLOC_FAILED ); 352 353 cur = cur->next; 354 } 355 356 cur->buf.p = start; 357 cur->buf.len = len; 358 cur->buf.tag = tag; 359 360 cb_ctx->cur = cur; 361 return( 0 ); 362 } 363 364 /* 365 * Parses and splits an ASN.1 "SEQUENCE OF <tag>" 366 */ 367 int mbedtls_asn1_get_sequence_of( unsigned char **p, 368 const unsigned char *end, 369 mbedtls_asn1_sequence *cur, 370 int tag) 371 { 372 asn1_get_sequence_of_cb_ctx_t cb_ctx = { tag, cur }; 373 memset( cur, 0, sizeof( mbedtls_asn1_sequence ) ); 374 return( mbedtls_asn1_traverse_sequence_of( 375 p, end, 0xFF, tag, 0, 0, 376 asn1_get_sequence_of_cb, &cb_ctx ) ); 377 } 378 379 int mbedtls_asn1_get_alg( unsigned char **p, 380 const unsigned char *end, 381 mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params ) 382 { 383 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 384 size_t len; 385 386 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, 387 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) 388 return( ret ); 389 390 if( ( end - *p ) < 1 ) 391 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); 392 393 alg->tag = **p; 394 end = *p + len; 395 396 if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 ) 397 return( ret ); 398 399 alg->p = *p; 400 *p += alg->len; 401 402 if( *p == end ) 403 { 404 mbedtls_platform_zeroize( params, sizeof(mbedtls_asn1_buf) ); 405 return( 0 ); 406 } 407 408 params->tag = **p; 409 (*p)++; 410 411 if( ( ret = mbedtls_asn1_get_len( p, end, ¶ms->len ) ) != 0 ) 412 return( ret ); 413 414 params->p = *p; 415 *p += params->len; 416 417 if( *p != end ) 418 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ); 419 420 return( 0 ); 421 } 422 423 int mbedtls_asn1_get_alg_null( unsigned char **p, 424 const unsigned char *end, 425 mbedtls_asn1_buf *alg ) 426 { 427 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 428 mbedtls_asn1_buf params; 429 430 memset( ¶ms, 0, sizeof(mbedtls_asn1_buf) ); 431 432 if( ( ret = mbedtls_asn1_get_alg( p, end, alg, ¶ms ) ) != 0 ) 433 return( ret ); 434 435 if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 ) 436 return( MBEDTLS_ERR_ASN1_INVALID_DATA ); 437 438 return( 0 ); 439 } 440 441 void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur ) 442 { 443 if( cur == NULL ) 444 return; 445 446 mbedtls_free( cur->oid.p ); 447 mbedtls_free( cur->val.p ); 448 449 mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_named_data ) ); 450 } 451 452 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head ) 453 { 454 mbedtls_asn1_named_data *cur; 455 456 while( ( cur = *head ) != NULL ) 457 { 458 *head = cur->next; 459 mbedtls_asn1_free_named_data( cur ); 460 mbedtls_free( cur ); 461 } 462 } 463 464 mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list, 465 const char *oid, size_t len ) 466 { 467 while( list != NULL ) 468 { 469 if( list->oid.len == len && 470 memcmp( list->oid.p, oid, len ) == 0 ) 471 { 472 break; 473 } 474 475 list = list->next; 476 } 477 478 return( list ); 479 } 480 481 #endif /* MBEDTLS_ASN1_PARSE_C */ 482