1 /* $OpenBSD: bytestring.h,v 1.20 2021/12/15 17:23:34 jsing Exp $ */ 2 /* 3 * Copyright (c) 2014, Google Inc. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 12 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 14 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 15 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #ifndef OPENSSL_HEADER_BYTESTRING_H 19 #define OPENSSL_HEADER_BYTESTRING_H 20 21 #include <sys/types.h> 22 #include <stdint.h> 23 24 __BEGIN_HIDDEN_DECLS 25 26 /* 27 * Bytestrings are used for parsing and building TLS and ASN.1 messages. 28 * 29 * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and 30 * provides utility functions for safely parsing length-prefixed structures 31 * like TLS and ASN.1 from it. 32 * 33 * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and 34 * provides utility functions for building length-prefixed messages. 35 */ 36 37 /* CRYPTO ByteString */ 38 typedef struct cbs_st { 39 const uint8_t *data; 40 size_t initial_len; 41 size_t len; 42 } CBS; 43 44 /* 45 * CBS_init sets |cbs| to point to |data|. It does not take ownership of 46 * |data|. 47 */ 48 void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 49 50 /* 51 * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 52 * otherwise. 53 */ 54 int CBS_skip(CBS *cbs, size_t len); 55 56 /* 57 * CBS_data returns a pointer to the contents of |cbs|. 58 */ 59 const uint8_t *CBS_data(const CBS *cbs); 60 61 /* 62 * CBS_len returns the number of bytes remaining in |cbs|. 63 */ 64 size_t CBS_len(const CBS *cbs); 65 66 /* 67 * CBS_offset returns the current offset into the original data of |cbs|. 68 */ 69 size_t CBS_offset(const CBS *cbs); 70 71 /* 72 * CBS_stow copies the current contents of |cbs| into |*out_ptr| and 73 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 74 * free. It returns one on success and zero on allocation failure. On 75 * success, |*out_ptr| should be freed with free. If |cbs| is empty, 76 * |*out_ptr| will be NULL. 77 */ 78 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 79 80 /* 81 * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 82 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 83 * with free. It returns one on success and zero on allocation 84 * failure. On success, |*out_ptr| should be freed with free. 85 * 86 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 87 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. 88 */ 89 int CBS_strdup(const CBS *cbs, char **out_ptr); 90 91 /* 92 * CBS_write_bytes writes all of the remaining data from |cbs| into |dst| 93 * if it is at most |dst_len| bytes. If |copied| is not NULL, it will be set 94 * to the amount copied. It returns one on success and zero otherwise. 95 */ 96 int CBS_write_bytes(const CBS *cbs, uint8_t *dst, size_t dst_len, 97 size_t *copied); 98 99 /* 100 * CBS_contains_zero_byte returns one if the current contents of |cbs| contains 101 * a NUL byte and zero otherwise. 102 */ 103 int CBS_contains_zero_byte(const CBS *cbs); 104 105 /* 106 * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 107 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 108 * lengths match, it uses a constant-time comparison. 109 */ 110 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); 111 112 /* 113 * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 114 * returns one on success and zero on error. 115 */ 116 int CBS_get_u8(CBS *cbs, uint8_t *out); 117 118 /* 119 * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 120 * advances |cbs|. It returns one on success and zero on error. 121 */ 122 int CBS_get_u16(CBS *cbs, uint16_t *out); 123 124 /* 125 * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 126 * advances |cbs|. It returns one on success and zero on error. 127 */ 128 int CBS_get_u24(CBS *cbs, uint32_t *out); 129 130 /* 131 * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 132 * and advances |cbs|. It returns one on success and zero on error. 133 */ 134 int CBS_get_u32(CBS *cbs, uint32_t *out); 135 136 /* 137 * CBS_get_last_u8 sets |*out| to the last uint8_t from |cbs| and shortens 138 * |cbs|. It returns one on success and zero on error. 139 */ 140 int CBS_get_last_u8(CBS *cbs, uint8_t *out); 141 142 /* 143 * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 144 * |cbs|. It returns one on success and zero on error. 145 */ 146 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 147 148 /* 149 * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 150 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 151 * on success and zero on error. 152 */ 153 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 154 155 /* 156 * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 157 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 158 * returns one on success and zero on error. 159 */ 160 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 161 162 /* 163 * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 164 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 165 * returns one on success and zero on error. 166 */ 167 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 168 169 170 /* Parsing ASN.1 */ 171 172 /* 173 * While an identifier can be multiple octets, this library only handles the 174 * single octet variety currently. This limits support up to tag number 30 175 * since tag number 31 is a reserved value to indicate multiple octets. 176 */ 177 178 /* Bits 8 and 7: class tag type: See X.690 section 8.1.2.2. */ 179 #define CBS_ASN1_UNIVERSAL 0x00 180 #define CBS_ASN1_APPLICATION 0x40 181 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 182 #define CBS_ASN1_PRIVATE 0xc0 183 184 /* Bit 6: Primitive or constructed: See X.690 section 8.1.2.3. */ 185 #define CBS_ASN1_PRIMITIVE 0x00 186 #define CBS_ASN1_CONSTRUCTED 0x20 187 188 /* 189 * Bits 5 to 1 are the tag number. See X.680 section 8.6 for tag numbers of 190 * the universal class. 191 */ 192 193 /* 194 * Common universal identifier octets. 195 * See X.690 section 8.1 and X.680 section 8.6 for universal tag numbers. 196 * 197 * Note: These definitions are the cause of some of the strange behavior in 198 * CBS's bs_ber.c. 199 * 200 * In BER, it is the sender's option to use primitive or constructed for 201 * bitstring (X.690 section 8.6.1) and octetstring (X.690 section 8.7.1). 202 * 203 * In DER, bitstring and octetstring are required to be primitive 204 * (X.690 section 10.2). 205 */ 206 #define CBS_ASN1_BOOLEAN (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x1) 207 #define CBS_ASN1_INTEGER (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x2) 208 #define CBS_ASN1_BITSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x3) 209 #define CBS_ASN1_OCTETSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x4) 210 #define CBS_ASN1_OBJECT (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x6) 211 #define CBS_ASN1_ENUMERATED (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0xa) 212 #define CBS_ASN1_SEQUENCE (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x10) 213 #define CBS_ASN1_SET (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x11) 214 215 /* 216 * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 217 * including tag and length bytes) and advances |cbs| over it. The ASN.1 218 * element must match |tag_value|. It returns one on success and zero 219 * on error. 220 * 221 * Tag numbers greater than 30 are not supported (i.e. short form only). 222 */ 223 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned int tag_value); 224 225 /* 226 * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 227 * ASN.1 header bytes too. 228 */ 229 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned int tag_value); 230 231 /* 232 * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 233 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 234 * |cbs| is empty or the tag does not match, it returns zero. Note: if 235 * it returns one, CBS_get_asn1 may still fail if the rest of the 236 * element is malformed. 237 */ 238 int CBS_peek_asn1_tag(const CBS *cbs, unsigned int tag_value); 239 240 /* 241 * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 242 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 243 * the tag number and |*out_header_len| to the length of the ASN.1 header. 244 * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 245 * the value. 246 * 247 * Tag numbers greater than 30 are not supported (i.e. short form only). 248 */ 249 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned int *out_tag, 250 size_t *out_header_len); 251 252 /* 253 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 254 * and sets |*out| to its value. It returns one on success and zero on error, 255 * where error includes the integer being negative, or too large to represent 256 * in 64 bits. 257 */ 258 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 259 260 /* 261 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 262 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 263 * present, it sets |*out_present| to one, otherwise zero. It returns 264 * one on success, whether or not the element was present, and zero on 265 * decode failure. 266 */ 267 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, 268 unsigned int tag); 269 270 /* 271 * CBS_get_optional_asn1_octet_string gets an optional 272 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 273 * |*out| to the string and |*out_present| to one. Otherwise, it sets 274 * |*out| to empty and |*out_present| to zero. |out_present| may be 275 * NULL. It returns one on success, whether or not the element was 276 * present, and zero on decode failure. 277 */ 278 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 279 unsigned int tag); 280 281 /* 282 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 283 * INTEGER from |cbs|. If present, it sets |*out| to the 284 * value. Otherwise, it sets |*out| to |default_value|. It returns one 285 * on success, whether or not the element was present, and zero on 286 * decode failure. 287 */ 288 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned int tag, 289 uint64_t default_value); 290 291 /* 292 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 293 * |cbs|. If present, it sets |*out| to either zero or one, based on the 294 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 295 * success, whether or not the element was present, and zero on decode 296 * failure. 297 */ 298 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned int tag, 299 int default_value); 300 301 302 /* 303 * CRYPTO ByteBuilder. 304 * 305 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 306 * object is associated with a buffer and new buffers are created with 307 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 308 * length-prefix is pending, however only a single |CBB| can be 'current' at 309 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 310 * the new |CBB| points at the same buffer as the original. But if the original 311 * |CBB| is used then the length prefix is written out and the new |CBB| must 312 * not be used again. 313 * 314 * If one needs to force a length prefix to be written out because a |CBB| is 315 * going out of scope, use |CBB_flush|. 316 */ 317 318 struct cbb_buffer_st { 319 uint8_t *buf; 320 321 /* The number of valid bytes. */ 322 size_t len; 323 324 /* The size of buf. */ 325 size_t cap; 326 327 /* 328 * One iff |buf| is owned by this object. If not then |buf| cannot be 329 * resized. 330 */ 331 char can_resize; 332 }; 333 334 typedef struct cbb_st { 335 struct cbb_buffer_st *base; 336 337 /* 338 * offset is the offset from the start of |base->buf| to the position of any 339 * pending length-prefix. 340 */ 341 size_t offset; 342 343 /* child points to a child CBB if a length-prefix is pending. */ 344 struct cbb_st *child; 345 346 /* 347 * pending_len_len contains the number of bytes in a pending length-prefix, 348 * or zero if no length-prefix is pending. 349 */ 350 uint8_t pending_len_len; 351 352 char pending_is_asn1; 353 354 /* 355 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 356 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 357 */ 358 char is_top_level; 359 } CBB; 360 361 /* 362 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 363 * needed, the |initial_capacity| is just a hint. It returns one on success or 364 * zero on error. 365 */ 366 int CBB_init(CBB *cbb, size_t initial_capacity); 367 368 /* 369 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 370 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 371 * functions to fail. It returns one on success or zero on error. 372 */ 373 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 374 375 /* 376 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 377 * writing to the same buffer. This should be used in an error case where a 378 * serialisation is abandoned. 379 */ 380 void CBB_cleanup(CBB *cbb); 381 382 /* 383 * CBB_finish completes any pending length prefix and sets |*out_data| to a 384 * malloced buffer and |*out_len| to the length of that buffer. The caller 385 * takes ownership of the buffer and, unless the buffer was fixed with 386 * |CBB_init_fixed|, must call |free| when done. 387 * 388 * It can only be called on a "top level" |CBB|, i.e. one initialised with 389 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 390 * error. 391 */ 392 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 393 394 /* 395 * CBB_flush causes any pending length prefixes to be written out and any child 396 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 397 * on error. 398 */ 399 int CBB_flush(CBB *cbb); 400 401 /* 402 * CBB_discard_child discards the current unflushed child of |cbb|. Neither the 403 * child's contents nor the length prefix will be included in the output. 404 */ 405 void CBB_discard_child(CBB *cbb); 406 407 /* 408 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 409 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 410 * length. It returns one on success or zero on error. 411 */ 412 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 413 414 /* 415 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 416 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 417 * big-endian length. It returns one on success or zero on error. 418 */ 419 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 420 421 /* 422 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 423 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 424 * big-endian length. It returns one on success or zero on error. 425 */ 426 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 427 428 /* 429 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 430 * ASN.1 object can be written. The |tag| argument will be used as the tag for 431 * the object. Passing in |tag| number 31 will return in an error since only 432 * single octet identifiers are supported. It returns one on success or zero 433 * on error. 434 */ 435 int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned int tag); 436 437 /* 438 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 439 * success and zero otherwise. 440 */ 441 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 442 443 /* 444 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 445 * the beginning of that space. The caller must then write |len| bytes of 446 * actual contents to |*out_data|. It returns one on success and zero 447 * otherwise. 448 */ 449 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 450 451 /* 452 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 453 * success and zero otherwise. 454 */ 455 int CBB_add_u8(CBB *cbb, size_t value); 456 457 /* 458 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 459 * returns one on success and zero otherwise. 460 */ 461 int CBB_add_u16(CBB *cbb, size_t value); 462 463 /* 464 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 465 * returns one on success and zero otherwise. 466 */ 467 int CBB_add_u24(CBB *cbb, size_t value); 468 469 /* 470 * CBB_add_u32 appends a 32-bit, big-endian number from |value| to |cbb|. It 471 * returns one on success and zero otherwise. 472 */ 473 int CBB_add_u32(CBB *cbb, size_t value); 474 475 /* 476 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 477 * and writes |value| in its contents. It returns one on success and zero on 478 * error. 479 */ 480 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 481 482 #ifdef LIBRESSL_INTERNAL 483 /* 484 * CBS_dup sets |out| to point to cbs's |data| and |len|. It results in two 485 * CBS that point to the same buffer. 486 */ 487 void CBS_dup(const CBS *cbs, CBS *out); 488 489 /* 490 * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 491 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 492 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 493 * strict mode is disabled and the element has indefinite length then |*out| 494 * will only contain the header. Each of |out|, |out_tag|, and 495 * |out_header_len| may be NULL to ignore the value. 496 * 497 * Tag numbers greater than 30 are not supported (i.e. short form only). 498 */ 499 int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned int *out_tag, 500 size_t *out_header_len, int strict); 501 502 /* 503 * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it 504 * finds indefinite-length elements that otherwise appear to be valid DER, it 505 * attempts to convert the DER-like data to DER and sets |*out| and 506 * |*out_length| to describe a malloced buffer containing the DER data. 507 * Additionally, |*in| will be advanced over the ASN.1 data. 508 * 509 * If it doesn't find any indefinite-length elements then it sets |*out| to 510 * NULL and |*in| is unmodified. 511 * 512 * This is NOT a conversion from BER to DER. There are many restrictions when 513 * dealing with DER data. This is only concerned with one: indefinite vs. 514 * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output 515 * from NSS. 516 * 517 * It returns one on success and zero otherwise. 518 */ 519 int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len); 520 #endif /* LIBRESSL_INTERNAL */ 521 522 __END_HIDDEN_DECLS 523 524 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 525