1 /* $OpenBSD: bytestring.h,v 1.9 2015/06/16 06:37:58 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 len; 44 } CBS; 45 46 /* 47 * CBS_init sets |cbs| to point to |data|. It does not take ownership of 48 * |data|. 49 */ 50 void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 51 52 /* 53 * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 54 * otherwise. 55 */ 56 int CBS_skip(CBS *cbs, size_t len); 57 58 /* 59 * CBS_data returns a pointer to the contents of |cbs|. 60 */ 61 const uint8_t *CBS_data(const CBS *cbs); 62 63 /* 64 * CBS_len returns the number of bytes remaining in |cbs|. 65 */ 66 size_t CBS_len(const CBS *cbs); 67 68 /* 69 * CBS_stow copies the current contents of |cbs| into |*out_ptr| and 70 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 71 * free. It returns one on success and zero on allocation failure. On 72 * success, |*out_ptr| should be freed with free. If |cbs| is empty, 73 * |*out_ptr| will be NULL. 74 */ 75 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 76 77 /* 78 * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 79 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 80 * with free. It returns one on success and zero on allocation 81 * failure. On success, |*out_ptr| should be freed with free. 82 * 83 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 84 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. 85 */ 86 int CBS_strdup(const CBS *cbs, char **out_ptr); 87 88 /* 89 * CBS_contains_zero_byte returns one if the current contents of |cbs| contains 90 * a NUL byte and zero otherwise. 91 */ 92 int CBS_contains_zero_byte(const CBS *cbs); 93 94 /* 95 * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 96 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 97 * lengths match, it uses a constant-time comparison. 98 */ 99 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); 100 101 /* 102 * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 103 * returns one on success and zero on error. 104 */ 105 int CBS_get_u8(CBS *cbs, uint8_t *out); 106 107 /* 108 * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 109 * advances |cbs|. It returns one on success and zero on error. 110 */ 111 int CBS_get_u16(CBS *cbs, uint16_t *out); 112 113 /* 114 * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 115 * advances |cbs|. It returns one on success and zero on error. 116 */ 117 int CBS_get_u24(CBS *cbs, uint32_t *out); 118 119 /* 120 * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 121 * and advances |cbs|. It returns one on success and zero on error. 122 */ 123 int CBS_get_u32(CBS *cbs, uint32_t *out); 124 125 /* 126 * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 127 * |cbs|. It returns one on success and zero on error. 128 */ 129 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 130 131 /* 132 * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 133 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 134 * on success and zero on error. 135 */ 136 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 137 138 /* 139 * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 140 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 141 * returns one on success and zero on error. 142 */ 143 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 144 145 /* 146 * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 147 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 148 * returns one on success and zero on error. 149 */ 150 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 151 152 153 /* Parsing ASN.1 */ 154 155 /* 156 * While an identifier can be multiple octets, this library only handles the 157 * single octet variety currently. This limits support up to tag number 30 158 * since tag number 31 is a reserved value to indicate multiple octets. 159 */ 160 161 /* Bits 8 and 7: class tag type: See X.690 section 8.1.2.2. */ 162 #define CBS_ASN1_UNIVERSAL 0x00 163 #define CBS_ASN1_APPLICATION 0x40 164 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 165 #define CBS_ASN1_PRIVATE 0xc0 166 167 /* Bit 6: Primitive or constructed: See X.690 section 8.1.2.3. */ 168 #define CBS_ASN1_PRIMITIVE 0x00 169 #define CBS_ASN1_CONSTRUCTED 0x20 170 171 /* 172 * Bits 5 to 1 are the tag number. See X.680 section 8.6 for tag numbers of 173 * the universal class. 174 */ 175 176 /* 177 * Common universal identifier octets. 178 * See X.690 section 8.1 and X.680 section 8.6 for universal tag numbers. 179 * 180 * Note: These definitions are the cause of some of the strange behavior in 181 * CBS's bs_ber.c. 182 * 183 * In BER, it is the sender's option to use primitive or constructed for 184 * bitstring (X.690 section 8.6.1) and octetstring (X.690 section 8.7.1). 185 * 186 * In DER, bitstring and octetstring are required to be primitive 187 * (X.690 section 10.2). 188 */ 189 #define CBS_ASN1_BOOLEAN (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x1) 190 #define CBS_ASN1_INTEGER (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x2) 191 #define CBS_ASN1_BITSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x3) 192 #define CBS_ASN1_OCTETSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x4) 193 #define CBS_ASN1_OBJECT (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x6) 194 #define CBS_ASN1_ENUMERATED (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0xa) 195 #define CBS_ASN1_SEQUENCE (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x10) 196 #define CBS_ASN1_SET (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x11) 197 198 /* 199 * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 200 * including tag and length bytes) and advances |cbs| over it. The ASN.1 201 * element must match |tag_value|. It returns one on success and zero 202 * on error. 203 * 204 * Tag numbers greater than 30 are not supported (i.e. short form only). 205 */ 206 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 207 208 /* 209 * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 210 * ASN.1 header bytes too. 211 */ 212 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 213 214 /* 215 * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 216 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 217 * |cbs| is empty or the tag does not match, it returns zero. Note: if 218 * it returns one, CBS_get_asn1 may still fail if the rest of the 219 * element is malformed. 220 */ 221 int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value); 222 223 /* 224 * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 225 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 226 * the tag number and |*out_header_len| to the length of the ASN.1 header. 227 * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 228 * the value. 229 * 230 * Tag numbers greater than 30 are not supported (i.e. short form only). 231 */ 232 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 233 size_t *out_header_len); 234 235 /* 236 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 237 * and sets |*out| to its value. It returns one on success and zero on error, 238 * where error includes the integer being negative, or too large to represent 239 * in 64 bits. 240 */ 241 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 242 243 /* 244 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 245 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 246 * present, it sets |*out_present| to one, otherwise zero. It returns 247 * one on success, whether or not the element was present, and zero on 248 * decode failure. 249 */ 250 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag); 251 252 /* 253 * CBS_get_optional_asn1_octet_string gets an optional 254 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 255 * |*out| to the string and |*out_present| to one. Otherwise, it sets 256 * |*out| to empty and |*out_present| to zero. |out_present| may be 257 * NULL. It returns one on success, whether or not the element was 258 * present, and zero on decode failure. 259 */ 260 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 261 unsigned tag); 262 263 /* 264 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 265 * INTEGER from |cbs|. If present, it sets |*out| to the 266 * value. Otherwise, it sets |*out| to |default_value|. It returns one 267 * on success, whether or not the element was present, and zero on 268 * decode failure. 269 */ 270 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, 271 uint64_t default_value); 272 273 /* 274 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 275 * |cbs|. If present, it sets |*out| to either zero or one, based on the 276 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 277 * success, whether or not the element was present, and zero on decode 278 * failure. 279 */ 280 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 281 int default_value); 282 283 284 /* 285 * CRYPTO ByteBuilder. 286 * 287 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 288 * object is associated with a buffer and new buffers are created with 289 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 290 * length-prefix is pending, however only a single |CBB| can be 'current' at 291 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 292 * the new |CBB| points at the same buffer as the original. But if the original 293 * |CBB| is used then the length prefix is written out and the new |CBB| must 294 * not be used again. 295 * 296 * If one needs to force a length prefix to be written out because a |CBB| is 297 * going out of scope, use |CBB_flush|. 298 */ 299 300 struct cbb_buffer_st { 301 uint8_t *buf; 302 303 /* The number of valid bytes. */ 304 size_t len; 305 306 /* The size of buf. */ 307 size_t cap; 308 309 /* 310 * One iff |buf| is owned by this object. If not then |buf| cannot be 311 * resized. 312 */ 313 char can_resize; 314 }; 315 316 typedef struct cbb_st { 317 struct cbb_buffer_st *base; 318 319 /* 320 * offset is the offset from the start of |base->buf| to the position of any 321 * pending length-prefix. 322 */ 323 size_t offset; 324 325 /* child points to a child CBB if a length-prefix is pending. */ 326 struct cbb_st *child; 327 328 /* 329 * pending_len_len contains the number of bytes in a pending length-prefix, 330 * or zero if no length-prefix is pending. 331 */ 332 uint8_t pending_len_len; 333 334 char pending_is_asn1; 335 336 /* 337 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 338 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 339 */ 340 char is_top_level; 341 } CBB; 342 343 /* 344 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 345 * needed, the |initial_capacity| is just a hint. It returns one on success or 346 * zero on error. 347 */ 348 int CBB_init(CBB *cbb, size_t initial_capacity); 349 350 /* 351 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 352 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 353 * functions to fail. It returns one on success or zero on error. 354 */ 355 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 356 357 /* 358 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 359 * writing to the same buffer. This should be used in an error case where a 360 * serialisation is abandoned. 361 */ 362 void CBB_cleanup(CBB *cbb); 363 364 /* 365 * CBB_finish completes any pending length prefix and sets |*out_data| to a 366 * malloced buffer and |*out_len| to the length of that buffer. The caller 367 * takes ownership of the buffer and, unless the buffer was fixed with 368 * |CBB_init_fixed|, must call |free| when done. 369 * 370 * It can only be called on a "top level" |CBB|, i.e. one initialised with 371 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 372 * error. 373 */ 374 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 375 376 /* 377 * CBB_flush causes any pending length prefixes to be written out and any child 378 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 379 * on error. 380 */ 381 int CBB_flush(CBB *cbb); 382 383 /* 384 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 385 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 386 * length. It returns one on success or zero on error. 387 */ 388 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 389 390 /* 391 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 392 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 393 * big-endian length. It returns one on success or zero on error. 394 */ 395 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 396 397 /* 398 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 399 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 400 * big-endian length. It returns one on success or zero on error. 401 */ 402 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 403 404 /* 405 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 406 * ASN.1 object can be written. The |tag| argument will be used as the tag for 407 * the object. Passing in |tag| number 31 will return in an error since only 408 * single octet identifiers are supported. It returns one on success or zero 409 * on error. 410 */ 411 int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 412 413 /* 414 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 415 * success and zero otherwise. 416 */ 417 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 418 419 /* 420 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 421 * the beginning of that space. The caller must then write |len| bytes of 422 * actual contents to |*out_data|. It returns one on success and zero 423 * otherwise. 424 */ 425 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 426 427 /* 428 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 429 * success and zero otherwise. 430 */ 431 int CBB_add_u8(CBB *cbb, uint8_t value); 432 433 /* 434 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 435 * returns one on success and zero otherwise. 436 */ 437 int CBB_add_u16(CBB *cbb, uint16_t value); 438 439 /* 440 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 441 * returns one on success and zero otherwise. 442 */ 443 int CBB_add_u24(CBB *cbb, uint32_t value); 444 445 /* 446 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 447 * and writes |value| in its contents. It returns one on success and zero on 448 * error. 449 */ 450 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 451 452 #ifdef LIBRESSL_INTERNAL 453 /* 454 * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 455 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 456 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 457 * strict mode is disabled and the element has indefinite length then |*out| 458 * will only contain the header. Each of |out|, |out_tag|, and 459 * |out_header_len| may be NULL to ignore the value. 460 * 461 * Tag numbers greater than 30 are not supported (i.e. short form only). 462 */ 463 int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned *out_tag, 464 size_t *out_header_len, int strict); 465 466 /* 467 * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it 468 * finds indefinite-length elements that otherwise appear to be valid DER, it 469 * attempts to convert the DER-like data to DER and sets |*out| and 470 * |*out_length| to describe a malloced buffer containing the DER data. 471 * Additionally, |*in| will be advanced over the ASN.1 data. 472 * 473 * If it doesn't find any indefinite-length elements then it sets |*out| to 474 * NULL and |*in| is unmodified. 475 * 476 * This is NOT a conversion from BER to DER. There are many restrictions when 477 * dealing with DER data. This is only concerned with one: indefinite vs. 478 * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output 479 * from NSS. 480 * 481 * It returns one on success and zero otherwise. 482 */ 483 int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len); 484 #endif /* LIBRESSL_INTERNAL */ 485 486 #if defined(__cplusplus) 487 } /* extern C */ 488 #endif 489 490 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 491