1 /* $OpenBSD: bytestring.h,v 1.11 2015/06/17 07:06:22 doug 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 #if defined(__cplusplus) 21 extern "C" { 22 #endif 23 24 #include <sys/types.h> 25 #include <stdint.h> 26 27 #include <openssl/opensslconf.h> 28 29 /* 30 * Bytestrings are used for parsing and building TLS and ASN.1 messages. 31 * 32 * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and 33 * provides utility functions for safely parsing length-prefixed structures 34 * like TLS and ASN.1 from it. 35 * 36 * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and 37 * provides utility functions for building length-prefixed messages. 38 */ 39 40 /* CRYPTO ByteString */ 41 typedef struct cbs_st { 42 const uint8_t *data; 43 size_t initial_len; 44 size_t len; 45 } CBS; 46 47 /* 48 * CBS_init sets |cbs| to point to |data|. It does not take ownership of 49 * |data|. 50 */ 51 void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 52 53 /* 54 * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 55 * otherwise. 56 */ 57 int CBS_skip(CBS *cbs, size_t len); 58 59 /* 60 * CBS_data returns a pointer to the contents of |cbs|. 61 */ 62 const uint8_t *CBS_data(const CBS *cbs); 63 64 /* 65 * CBS_len returns the number of bytes remaining in |cbs|. 66 */ 67 size_t CBS_len(const CBS *cbs); 68 69 /* 70 * CBS_offset returns the current offset into the original data of |cbs|. 71 */ 72 size_t CBS_offset(const CBS *cbs); 73 74 /* 75 * CBS_stow copies the current contents of |cbs| into |*out_ptr| and 76 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 77 * free. It returns one on success and zero on allocation failure. On 78 * success, |*out_ptr| should be freed with free. If |cbs| is empty, 79 * |*out_ptr| will be NULL. 80 */ 81 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 82 83 /* 84 * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 85 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 86 * with free. It returns one on success and zero on allocation 87 * failure. On success, |*out_ptr| should be freed with free. 88 * 89 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 90 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. 91 */ 92 int CBS_strdup(const CBS *cbs, char **out_ptr); 93 94 /* 95 * CBS_write_bytes writes all of the remaining data from |cbs| into |dst| 96 * if it is at most |dst_len| bytes. If |copied| is not NULL, it will be set 97 * to the amount copied. It returns one on success and zero otherwise. 98 */ 99 int CBS_write_bytes(const CBS *cbs, uint8_t *dst, size_t dst_len, 100 size_t *copied); 101 102 /* 103 * CBS_contains_zero_byte returns one if the current contents of |cbs| contains 104 * a NUL byte and zero otherwise. 105 */ 106 int CBS_contains_zero_byte(const CBS *cbs); 107 108 /* 109 * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 110 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 111 * lengths match, it uses a constant-time comparison. 112 */ 113 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); 114 115 /* 116 * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 117 * returns one on success and zero on error. 118 */ 119 int CBS_get_u8(CBS *cbs, uint8_t *out); 120 121 /* 122 * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 123 * advances |cbs|. It returns one on success and zero on error. 124 */ 125 int CBS_get_u16(CBS *cbs, uint16_t *out); 126 127 /* 128 * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 129 * advances |cbs|. It returns one on success and zero on error. 130 */ 131 int CBS_get_u24(CBS *cbs, uint32_t *out); 132 133 /* 134 * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 135 * and advances |cbs|. It returns one on success and zero on error. 136 */ 137 int CBS_get_u32(CBS *cbs, uint32_t *out); 138 139 /* 140 * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 141 * |cbs|. It returns one on success and zero on error. 142 */ 143 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 144 145 /* 146 * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 147 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 148 * on success and zero on error. 149 */ 150 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 151 152 /* 153 * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 154 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 155 * returns one on success and zero on error. 156 */ 157 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 158 159 /* 160 * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 161 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 162 * returns one on success and zero on error. 163 */ 164 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 165 166 167 /* Parsing ASN.1 */ 168 169 /* 170 * While an identifier can be multiple octets, this library only handles the 171 * single octet variety currently. This limits support up to tag number 30 172 * since tag number 31 is a reserved value to indicate multiple octets. 173 */ 174 175 /* Bits 8 and 7: class tag type: See X.690 section 8.1.2.2. */ 176 #define CBS_ASN1_UNIVERSAL 0x00 177 #define CBS_ASN1_APPLICATION 0x40 178 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 179 #define CBS_ASN1_PRIVATE 0xc0 180 181 /* Bit 6: Primitive or constructed: See X.690 section 8.1.2.3. */ 182 #define CBS_ASN1_PRIMITIVE 0x00 183 #define CBS_ASN1_CONSTRUCTED 0x20 184 185 /* 186 * Bits 5 to 1 are the tag number. See X.680 section 8.6 for tag numbers of 187 * the universal class. 188 */ 189 190 /* 191 * Common universal identifier octets. 192 * See X.690 section 8.1 and X.680 section 8.6 for universal tag numbers. 193 * 194 * Note: These definitions are the cause of some of the strange behavior in 195 * CBS's bs_ber.c. 196 * 197 * In BER, it is the sender's option to use primitive or constructed for 198 * bitstring (X.690 section 8.6.1) and octetstring (X.690 section 8.7.1). 199 * 200 * In DER, bitstring and octetstring are required to be primitive 201 * (X.690 section 10.2). 202 */ 203 #define CBS_ASN1_BOOLEAN (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x1) 204 #define CBS_ASN1_INTEGER (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x2) 205 #define CBS_ASN1_BITSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x3) 206 #define CBS_ASN1_OCTETSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x4) 207 #define CBS_ASN1_OBJECT (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x6) 208 #define CBS_ASN1_ENUMERATED (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0xa) 209 #define CBS_ASN1_SEQUENCE (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x10) 210 #define CBS_ASN1_SET (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x11) 211 212 /* 213 * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 214 * including tag and length bytes) and advances |cbs| over it. The ASN.1 215 * element must match |tag_value|. It returns one on success and zero 216 * on error. 217 * 218 * Tag numbers greater than 30 are not supported (i.e. short form only). 219 */ 220 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 221 222 /* 223 * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 224 * ASN.1 header bytes too. 225 */ 226 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 227 228 /* 229 * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 230 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 231 * |cbs| is empty or the tag does not match, it returns zero. Note: if 232 * it returns one, CBS_get_asn1 may still fail if the rest of the 233 * element is malformed. 234 */ 235 int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value); 236 237 /* 238 * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 239 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 240 * the tag number and |*out_header_len| to the length of the ASN.1 header. 241 * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 242 * the value. 243 * 244 * Tag numbers greater than 30 are not supported (i.e. short form only). 245 */ 246 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 247 size_t *out_header_len); 248 249 /* 250 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 251 * and sets |*out| to its value. It returns one on success and zero on error, 252 * where error includes the integer being negative, or too large to represent 253 * in 64 bits. 254 */ 255 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 256 257 /* 258 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 259 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 260 * present, it sets |*out_present| to one, otherwise zero. It returns 261 * one on success, whether or not the element was present, and zero on 262 * decode failure. 263 */ 264 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag); 265 266 /* 267 * CBS_get_optional_asn1_octet_string gets an optional 268 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 269 * |*out| to the string and |*out_present| to one. Otherwise, it sets 270 * |*out| to empty and |*out_present| to zero. |out_present| may be 271 * NULL. It returns one on success, whether or not the element was 272 * present, and zero on decode failure. 273 */ 274 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 275 unsigned tag); 276 277 /* 278 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 279 * INTEGER from |cbs|. If present, it sets |*out| to the 280 * value. Otherwise, it sets |*out| to |default_value|. It returns one 281 * on success, whether or not the element was present, and zero on 282 * decode failure. 283 */ 284 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, 285 uint64_t default_value); 286 287 /* 288 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 289 * |cbs|. If present, it sets |*out| to either zero or one, based on the 290 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 291 * success, whether or not the element was present, and zero on decode 292 * failure. 293 */ 294 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 295 int default_value); 296 297 298 /* 299 * CRYPTO ByteBuilder. 300 * 301 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 302 * object is associated with a buffer and new buffers are created with 303 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 304 * length-prefix is pending, however only a single |CBB| can be 'current' at 305 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 306 * the new |CBB| points at the same buffer as the original. But if the original 307 * |CBB| is used then the length prefix is written out and the new |CBB| must 308 * not be used again. 309 * 310 * If one needs to force a length prefix to be written out because a |CBB| is 311 * going out of scope, use |CBB_flush|. 312 */ 313 314 struct cbb_buffer_st { 315 uint8_t *buf; 316 317 /* The number of valid bytes. */ 318 size_t len; 319 320 /* The size of buf. */ 321 size_t cap; 322 323 /* 324 * One iff |buf| is owned by this object. If not then |buf| cannot be 325 * resized. 326 */ 327 char can_resize; 328 }; 329 330 typedef struct cbb_st { 331 struct cbb_buffer_st *base; 332 333 /* 334 * offset is the offset from the start of |base->buf| to the position of any 335 * pending length-prefix. 336 */ 337 size_t offset; 338 339 /* child points to a child CBB if a length-prefix is pending. */ 340 struct cbb_st *child; 341 342 /* 343 * pending_len_len contains the number of bytes in a pending length-prefix, 344 * or zero if no length-prefix is pending. 345 */ 346 uint8_t pending_len_len; 347 348 char pending_is_asn1; 349 350 /* 351 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 352 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 353 */ 354 char is_top_level; 355 } CBB; 356 357 /* 358 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 359 * needed, the |initial_capacity| is just a hint. It returns one on success or 360 * zero on error. 361 */ 362 int CBB_init(CBB *cbb, size_t initial_capacity); 363 364 /* 365 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 366 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 367 * functions to fail. It returns one on success or zero on error. 368 */ 369 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 370 371 /* 372 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 373 * writing to the same buffer. This should be used in an error case where a 374 * serialisation is abandoned. 375 */ 376 void CBB_cleanup(CBB *cbb); 377 378 /* 379 * CBB_finish completes any pending length prefix and sets |*out_data| to a 380 * malloced buffer and |*out_len| to the length of that buffer. The caller 381 * takes ownership of the buffer and, unless the buffer was fixed with 382 * |CBB_init_fixed|, must call |free| when done. 383 * 384 * It can only be called on a "top level" |CBB|, i.e. one initialised with 385 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 386 * error. 387 */ 388 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 389 390 /* 391 * CBB_flush causes any pending length prefixes to be written out and any child 392 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 393 * on error. 394 */ 395 int CBB_flush(CBB *cbb); 396 397 /* 398 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 399 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 400 * length. It returns one on success or zero on error. 401 */ 402 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 403 404 /* 405 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 406 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 407 * big-endian length. It returns one on success or zero on error. 408 */ 409 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 410 411 /* 412 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 413 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 414 * big-endian length. It returns one on success or zero on error. 415 */ 416 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 417 418 /* 419 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 420 * ASN.1 object can be written. The |tag| argument will be used as the tag for 421 * the object. Passing in |tag| number 31 will return in an error since only 422 * single octet identifiers are supported. It returns one on success or zero 423 * on error. 424 */ 425 int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 426 427 /* 428 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 429 * success and zero otherwise. 430 */ 431 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 432 433 /* 434 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 435 * the beginning of that space. The caller must then write |len| bytes of 436 * actual contents to |*out_data|. It returns one on success and zero 437 * otherwise. 438 */ 439 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 440 441 /* 442 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 443 * success and zero otherwise. 444 */ 445 int CBB_add_u8(CBB *cbb, uint8_t value); 446 447 /* 448 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 449 * returns one on success and zero otherwise. 450 */ 451 int CBB_add_u16(CBB *cbb, uint16_t value); 452 453 /* 454 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 455 * returns one on success and zero otherwise. 456 */ 457 int CBB_add_u24(CBB *cbb, uint32_t value); 458 459 /* 460 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 461 * and writes |value| in its contents. It returns one on success and zero on 462 * error. 463 */ 464 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 465 466 #ifdef LIBRESSL_INTERNAL 467 /* 468 * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 469 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 470 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 471 * strict mode is disabled and the element has indefinite length then |*out| 472 * will only contain the header. Each of |out|, |out_tag|, and 473 * |out_header_len| may be NULL to ignore the value. 474 * 475 * Tag numbers greater than 30 are not supported (i.e. short form only). 476 */ 477 int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned *out_tag, 478 size_t *out_header_len, int strict); 479 480 /* 481 * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it 482 * finds indefinite-length elements that otherwise appear to be valid DER, it 483 * attempts to convert the DER-like data to DER and sets |*out| and 484 * |*out_length| to describe a malloced buffer containing the DER data. 485 * Additionally, |*in| will be advanced over the ASN.1 data. 486 * 487 * If it doesn't find any indefinite-length elements then it sets |*out| to 488 * NULL and |*in| is unmodified. 489 * 490 * This is NOT a conversion from BER to DER. There are many restrictions when 491 * dealing with DER data. This is only concerned with one: indefinite vs. 492 * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output 493 * from NSS. 494 * 495 * It returns one on success and zero otherwise. 496 */ 497 int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len); 498 #endif /* LIBRESSL_INTERNAL */ 499 500 #if defined(__cplusplus) 501 } /* extern C */ 502 #endif 503 504 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 505