1 /* $OpenBSD: bytestring.h,v 1.17 2018/08/16 18:39:37 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 #ifndef OPENSSL_HEADER_BYTESTRING_H 18 #define OPENSSL_HEADER_BYTESTRING_H 19 20 #include <sys/types.h> 21 #include <stdint.h> 22 23 #include <openssl/opensslconf.h> 24 25 __BEGIN_HIDDEN_DECLS 26 27 /* 28 * Bytestrings are used for parsing and building TLS and ASN.1 messages. 29 * 30 * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and 31 * provides utility functions for safely parsing length-prefixed structures 32 * like TLS and ASN.1 from it. 33 * 34 * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and 35 * provides utility functions for building length-prefixed messages. 36 */ 37 38 /* CRYPTO ByteString */ 39 typedef struct cbs_st { 40 const uint8_t *data; 41 size_t initial_len; 42 size_t len; 43 } CBS; 44 45 /* 46 * CBS_init sets |cbs| to point to |data|. It does not take ownership of 47 * |data|. 48 */ 49 void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 50 51 /* 52 * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 53 * otherwise. 54 */ 55 int CBS_skip(CBS *cbs, size_t len); 56 57 /* 58 * CBS_data returns a pointer to the contents of |cbs|. 59 */ 60 const uint8_t *CBS_data(const CBS *cbs); 61 62 /* 63 * CBS_len returns the number of bytes remaining in |cbs|. 64 */ 65 size_t CBS_len(const CBS *cbs); 66 67 /* 68 * CBS_offset returns the current offset into the original data of |cbs|. 69 */ 70 size_t CBS_offset(const CBS *cbs); 71 72 /* 73 * CBS_stow copies the current contents of |cbs| into |*out_ptr| and 74 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 75 * free. It returns one on success and zero on allocation failure. On 76 * success, |*out_ptr| should be freed with free. If |cbs| is empty, 77 * |*out_ptr| will be NULL. 78 */ 79 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 80 81 /* 82 * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 83 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 84 * with free. It returns one on success and zero on allocation 85 * failure. On success, |*out_ptr| should be freed with free. 86 * 87 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 88 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. 89 */ 90 int CBS_strdup(const CBS *cbs, char **out_ptr); 91 92 /* 93 * CBS_write_bytes writes all of the remaining data from |cbs| into |dst| 94 * if it is at most |dst_len| bytes. If |copied| is not NULL, it will be set 95 * to the amount copied. It returns one on success and zero otherwise. 96 */ 97 int CBS_write_bytes(const CBS *cbs, uint8_t *dst, size_t dst_len, 98 size_t *copied); 99 100 /* 101 * CBS_contains_zero_byte returns one if the current contents of |cbs| contains 102 * a NUL byte and zero otherwise. 103 */ 104 int CBS_contains_zero_byte(const CBS *cbs); 105 106 /* 107 * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 108 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 109 * lengths match, it uses a constant-time comparison. 110 */ 111 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); 112 113 /* 114 * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 115 * returns one on success and zero on error. 116 */ 117 int CBS_get_u8(CBS *cbs, uint8_t *out); 118 119 /* 120 * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 121 * advances |cbs|. It returns one on success and zero on error. 122 */ 123 int CBS_get_u16(CBS *cbs, uint16_t *out); 124 125 /* 126 * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 127 * advances |cbs|. It returns one on success and zero on error. 128 */ 129 int CBS_get_u24(CBS *cbs, uint32_t *out); 130 131 /* 132 * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 133 * and advances |cbs|. It returns one on success and zero on error. 134 */ 135 int CBS_get_u32(CBS *cbs, uint32_t *out); 136 137 /* 138 * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 139 * |cbs|. It returns one on success and zero on error. 140 */ 141 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 142 143 /* 144 * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 145 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 146 * on success and zero on error. 147 */ 148 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 149 150 /* 151 * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 152 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 153 * returns one on success and zero on error. 154 */ 155 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 156 157 /* 158 * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 159 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 160 * returns one on success and zero on error. 161 */ 162 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 163 164 165 /* Parsing ASN.1 */ 166 167 /* 168 * While an identifier can be multiple octets, this library only handles the 169 * single octet variety currently. This limits support up to tag number 30 170 * since tag number 31 is a reserved value to indicate multiple octets. 171 */ 172 173 /* Bits 8 and 7: class tag type: See X.690 section 8.1.2.2. */ 174 #define CBS_ASN1_UNIVERSAL 0x00 175 #define CBS_ASN1_APPLICATION 0x40 176 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 177 #define CBS_ASN1_PRIVATE 0xc0 178 179 /* Bit 6: Primitive or constructed: See X.690 section 8.1.2.3. */ 180 #define CBS_ASN1_PRIMITIVE 0x00 181 #define CBS_ASN1_CONSTRUCTED 0x20 182 183 /* 184 * Bits 5 to 1 are the tag number. See X.680 section 8.6 for tag numbers of 185 * the universal class. 186 */ 187 188 /* 189 * Common universal identifier octets. 190 * See X.690 section 8.1 and X.680 section 8.6 for universal tag numbers. 191 * 192 * Note: These definitions are the cause of some of the strange behavior in 193 * CBS's bs_ber.c. 194 * 195 * In BER, it is the sender's option to use primitive or constructed for 196 * bitstring (X.690 section 8.6.1) and octetstring (X.690 section 8.7.1). 197 * 198 * In DER, bitstring and octetstring are required to be primitive 199 * (X.690 section 10.2). 200 */ 201 #define CBS_ASN1_BOOLEAN (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x1) 202 #define CBS_ASN1_INTEGER (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x2) 203 #define CBS_ASN1_BITSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x3) 204 #define CBS_ASN1_OCTETSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x4) 205 #define CBS_ASN1_OBJECT (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x6) 206 #define CBS_ASN1_ENUMERATED (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0xa) 207 #define CBS_ASN1_SEQUENCE (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x10) 208 #define CBS_ASN1_SET (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x11) 209 210 /* 211 * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 212 * including tag and length bytes) and advances |cbs| over it. The ASN.1 213 * element must match |tag_value|. It returns one on success and zero 214 * on error. 215 * 216 * Tag numbers greater than 30 are not supported (i.e. short form only). 217 */ 218 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned int tag_value); 219 220 /* 221 * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 222 * ASN.1 header bytes too. 223 */ 224 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned int tag_value); 225 226 /* 227 * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 228 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 229 * |cbs| is empty or the tag does not match, it returns zero. Note: if 230 * it returns one, CBS_get_asn1 may still fail if the rest of the 231 * element is malformed. 232 */ 233 int CBS_peek_asn1_tag(const CBS *cbs, unsigned int tag_value); 234 235 /* 236 * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 237 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 238 * the tag number and |*out_header_len| to the length of the ASN.1 header. 239 * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 240 * the value. 241 * 242 * Tag numbers greater than 30 are not supported (i.e. short form only). 243 */ 244 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned int *out_tag, 245 size_t *out_header_len); 246 247 /* 248 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 249 * and sets |*out| to its value. It returns one on success and zero on error, 250 * where error includes the integer being negative, or too large to represent 251 * in 64 bits. 252 */ 253 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 254 255 /* 256 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 257 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 258 * present, it sets |*out_present| to one, otherwise zero. It returns 259 * one on success, whether or not the element was present, and zero on 260 * decode failure. 261 */ 262 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, 263 unsigned int tag); 264 265 /* 266 * CBS_get_optional_asn1_octet_string gets an optional 267 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 268 * |*out| to the string and |*out_present| to one. Otherwise, it sets 269 * |*out| to empty and |*out_present| to zero. |out_present| may be 270 * NULL. It returns one on success, whether or not the element was 271 * present, and zero on decode failure. 272 */ 273 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 274 unsigned int tag); 275 276 /* 277 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 278 * INTEGER from |cbs|. If present, it sets |*out| to the 279 * value. Otherwise, it sets |*out| to |default_value|. It returns one 280 * on success, whether or not the element was present, and zero on 281 * decode failure. 282 */ 283 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned int tag, 284 uint64_t default_value); 285 286 /* 287 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 288 * |cbs|. If present, it sets |*out| to either zero or one, based on the 289 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 290 * success, whether or not the element was present, and zero on decode 291 * failure. 292 */ 293 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned int tag, 294 int default_value); 295 296 297 /* 298 * CRYPTO ByteBuilder. 299 * 300 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 301 * object is associated with a buffer and new buffers are created with 302 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 303 * length-prefix is pending, however only a single |CBB| can be 'current' at 304 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 305 * the new |CBB| points at the same buffer as the original. But if the original 306 * |CBB| is used then the length prefix is written out and the new |CBB| must 307 * not be used again. 308 * 309 * If one needs to force a length prefix to be written out because a |CBB| is 310 * going out of scope, use |CBB_flush|. 311 */ 312 313 struct cbb_buffer_st { 314 uint8_t *buf; 315 316 /* The number of valid bytes. */ 317 size_t len; 318 319 /* The size of buf. */ 320 size_t cap; 321 322 /* 323 * One iff |buf| is owned by this object. If not then |buf| cannot be 324 * resized. 325 */ 326 char can_resize; 327 }; 328 329 typedef struct cbb_st { 330 struct cbb_buffer_st *base; 331 332 /* 333 * offset is the offset from the start of |base->buf| to the position of any 334 * pending length-prefix. 335 */ 336 size_t offset; 337 338 /* child points to a child CBB if a length-prefix is pending. */ 339 struct cbb_st *child; 340 341 /* 342 * pending_len_len contains the number of bytes in a pending length-prefix, 343 * or zero if no length-prefix is pending. 344 */ 345 uint8_t pending_len_len; 346 347 char pending_is_asn1; 348 349 /* 350 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 351 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 352 */ 353 char is_top_level; 354 } CBB; 355 356 /* 357 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 358 * needed, the |initial_capacity| is just a hint. It returns one on success or 359 * zero on error. 360 */ 361 int CBB_init(CBB *cbb, size_t initial_capacity); 362 363 /* 364 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 365 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 366 * functions to fail. It returns one on success or zero on error. 367 */ 368 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 369 370 /* 371 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 372 * writing to the same buffer. This should be used in an error case where a 373 * serialisation is abandoned. 374 */ 375 void CBB_cleanup(CBB *cbb); 376 377 /* 378 * CBB_finish completes any pending length prefix and sets |*out_data| to a 379 * malloced buffer and |*out_len| to the length of that buffer. The caller 380 * takes ownership of the buffer and, unless the buffer was fixed with 381 * |CBB_init_fixed|, must call |free| when done. 382 * 383 * It can only be called on a "top level" |CBB|, i.e. one initialised with 384 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 385 * error. 386 */ 387 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 388 389 /* 390 * CBB_flush causes any pending length prefixes to be written out and any child 391 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 392 * on error. 393 */ 394 int CBB_flush(CBB *cbb); 395 396 /* 397 * CBB_discard_child discards the current unflushed child of |cbb|. Neither the 398 * child's contents nor the length prefix will be included in the output. 399 */ 400 void CBB_discard_child(CBB *cbb); 401 402 /* 403 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 404 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 405 * length. It returns one on success or zero on error. 406 */ 407 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 408 409 /* 410 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 411 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 412 * big-endian length. It returns one on success or zero on error. 413 */ 414 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 415 416 /* 417 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 418 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 419 * big-endian length. It returns one on success or zero on error. 420 */ 421 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 422 423 /* 424 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 425 * ASN.1 object can be written. The |tag| argument will be used as the tag for 426 * the object. Passing in |tag| number 31 will return in an error since only 427 * single octet identifiers are supported. It returns one on success or zero 428 * on error. 429 */ 430 int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned int tag); 431 432 /* 433 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 434 * success and zero otherwise. 435 */ 436 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 437 438 /* 439 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 440 * the beginning of that space. The caller must then write |len| bytes of 441 * actual contents to |*out_data|. It returns one on success and zero 442 * otherwise. 443 */ 444 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 445 446 /* 447 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 448 * success and zero otherwise. 449 */ 450 int CBB_add_u8(CBB *cbb, size_t value); 451 452 /* 453 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 454 * returns one on success and zero otherwise. 455 */ 456 int CBB_add_u16(CBB *cbb, size_t value); 457 458 /* 459 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 460 * returns one on success and zero otherwise. 461 */ 462 int CBB_add_u24(CBB *cbb, size_t value); 463 464 /* 465 * CBB_add_u32 appends a 32-bit, big-endian number from |value| to |cbb|. It 466 * returns one on success and zero otherwise. 467 */ 468 int CBB_add_u32(CBB *cbb, size_t value); 469 470 /* 471 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 472 * and writes |value| in its contents. It returns one on success and zero on 473 * error. 474 */ 475 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 476 477 #ifdef LIBRESSL_INTERNAL 478 /* 479 * CBS_dup sets |out| to point to cbs's |data| and |len|. It results in two 480 * CBS that point to the same buffer. 481 */ 482 void CBS_dup(const CBS *cbs, CBS *out); 483 484 /* 485 * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 486 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 487 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 488 * strict mode is disabled and the element has indefinite length then |*out| 489 * will only contain the header. Each of |out|, |out_tag|, and 490 * |out_header_len| may be NULL to ignore the value. 491 * 492 * Tag numbers greater than 30 are not supported (i.e. short form only). 493 */ 494 int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned int *out_tag, 495 size_t *out_header_len, int strict); 496 497 /* 498 * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it 499 * finds indefinite-length elements that otherwise appear to be valid DER, it 500 * attempts to convert the DER-like data to DER and sets |*out| and 501 * |*out_length| to describe a malloced buffer containing the DER data. 502 * Additionally, |*in| will be advanced over the ASN.1 data. 503 * 504 * If it doesn't find any indefinite-length elements then it sets |*out| to 505 * NULL and |*in| is unmodified. 506 * 507 * This is NOT a conversion from BER to DER. There are many restrictions when 508 * dealing with DER data. This is only concerned with one: indefinite vs. 509 * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output 510 * from NSS. 511 * 512 * It returns one on success and zero otherwise. 513 */ 514 int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len); 515 #endif /* LIBRESSL_INTERNAL */ 516 517 __END_HIDDEN_DECLS 518 519 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 520