1 /* $OpenBSD: bytestring.h,v 1.6 2015/06/13 09:02:45 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. If 227 * the element has indefinite length then |*out| will only contain the 228 * header. Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 229 * the value. 230 * 231 * Tag numbers greater than 30 are not supported (i.e. short form only). 232 */ 233 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 234 size_t *out_header_len); 235 236 /* 237 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 238 * and sets |*out| to its value. It returns one on success and zero on error, 239 * where error includes the integer being negative, or too large to represent 240 * in 64 bits. 241 */ 242 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 243 244 /* 245 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 246 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 247 * present, it sets |*out_present| to one, otherwise zero. It returns 248 * one on success, whether or not the element was present, and zero on 249 * decode failure. 250 */ 251 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag); 252 253 /* 254 * CBS_get_optional_asn1_octet_string gets an optional 255 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 256 * |*out| to the string and |*out_present| to one. Otherwise, it sets 257 * |*out| to empty and |*out_present| to zero. |out_present| may be 258 * NULL. It returns one on success, whether or not the element was 259 * present, and zero on decode failure. 260 */ 261 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 262 unsigned tag); 263 264 /* 265 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 266 * INTEGER from |cbs|. If present, it sets |*out| to the 267 * value. Otherwise, it sets |*out| to |default_value|. It returns one 268 * on success, whether or not the element was present, and zero on 269 * decode failure. 270 */ 271 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, 272 uint64_t default_value); 273 274 /* 275 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 276 * |cbs|. If present, it sets |*out| to either zero or one, based on the 277 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 278 * success, whether or not the element was present, and zero on decode 279 * failure. 280 */ 281 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 282 int default_value); 283 284 285 /* 286 * CRYPTO ByteBuilder. 287 * 288 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 289 * object is associated with a buffer and new buffers are created with 290 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 291 * length-prefix is pending, however only a single |CBB| can be 'current' at 292 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 293 * the new |CBB| points at the same buffer as the original. But if the original 294 * |CBB| is used then the length prefix is written out and the new |CBB| must 295 * not be used again. 296 * 297 * If one needs to force a length prefix to be written out because a |CBB| is 298 * going out of scope, use |CBB_flush|. 299 */ 300 301 struct cbb_buffer_st { 302 uint8_t *buf; 303 304 /* The number of valid bytes. */ 305 size_t len; 306 307 /* The size of buf. */ 308 size_t cap; 309 310 /* 311 * One iff |buf| is owned by this object. If not then |buf| cannot be 312 * resized. 313 */ 314 char can_resize; 315 }; 316 317 typedef struct cbb_st { 318 struct cbb_buffer_st *base; 319 320 /* 321 * offset is the offset from the start of |base->buf| to the position of any 322 * pending length-prefix. 323 */ 324 size_t offset; 325 326 /* child points to a child CBB if a length-prefix is pending. */ 327 struct cbb_st *child; 328 329 /* 330 * pending_len_len contains the number of bytes in a pending length-prefix, 331 * or zero if no length-prefix is pending. 332 */ 333 uint8_t pending_len_len; 334 335 char pending_is_asn1; 336 337 /* 338 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 339 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 340 */ 341 char is_top_level; 342 } CBB; 343 344 /* 345 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 346 * needed, the |initial_capacity| is just a hint. It returns one on success or 347 * zero on error. 348 */ 349 int CBB_init(CBB *cbb, size_t initial_capacity); 350 351 /* 352 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 353 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 354 * functions to fail. It returns one on success or zero on error. 355 */ 356 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 357 358 /* 359 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 360 * writing to the same buffer. This should be used in an error case where a 361 * serialisation is abandoned. 362 */ 363 void CBB_cleanup(CBB *cbb); 364 365 /* 366 * CBB_finish completes any pending length prefix and sets |*out_data| to a 367 * malloced buffer and |*out_len| to the length of that buffer. The caller 368 * takes ownership of the buffer and, unless the buffer was fixed with 369 * |CBB_init_fixed|, must call |free| when done. 370 * 371 * It can only be called on a "top level" |CBB|, i.e. one initialised with 372 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 373 * error. 374 */ 375 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 376 377 /* 378 * CBB_flush causes any pending length prefixes to be written out and any child 379 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 380 * on error. 381 */ 382 int CBB_flush(CBB *cbb); 383 384 /* 385 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 386 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 387 * length. It returns one on success or zero on error. 388 */ 389 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 390 391 /* 392 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 393 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 394 * big-endian length. It returns one on success or zero on error. 395 */ 396 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 397 398 /* 399 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 400 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 401 * big-endian length. It returns one on success or zero on error. 402 */ 403 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 404 405 /* 406 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 407 * ASN.1 object can be written. The |tag| argument will be used as the tag for 408 * the object. Passing in |tag| number 31 will return in an error since only 409 * single octet identifiers are supported. It returns one on success or zero 410 * on error. 411 */ 412 int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 413 414 /* 415 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 416 * success and zero otherwise. 417 */ 418 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 419 420 /* 421 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 422 * the beginning of that space. The caller must then write |len| bytes of 423 * actual contents to |*out_data|. It returns one on success and zero 424 * otherwise. 425 */ 426 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 427 428 /* 429 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 430 * success and zero otherwise. 431 */ 432 int CBB_add_u8(CBB *cbb, uint8_t value); 433 434 /* 435 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 436 * returns one on success and zero otherwise. 437 */ 438 int CBB_add_u16(CBB *cbb, uint16_t value); 439 440 /* 441 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 442 * returns one on success and zero otherwise. 443 */ 444 int CBB_add_u24(CBB *cbb, uint32_t value); 445 446 /* 447 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 448 * and writes |value| in its contents. It returns one on success and zero on 449 * error. 450 */ 451 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 452 453 #ifdef LIBRESSL_INTERNAL 454 /* 455 * CBS_asn1_ber_to_der reads an ASN.1 structure from |in|. If it finds 456 * indefinite-length elements then it attempts to convert the BER data to DER 457 * and sets |*out| and |*out_length| to describe a malloced buffer containing 458 * the DER data. Additionally, |*in| will be advanced over the ASN.1 data. 459 * 460 * If it doesn't find any indefinite-length elements then it sets |*out| to 461 * NULL and |*in| is unmodified. 462 * 463 * A sufficiently complex ASN.1 structure will break this function because it's 464 * not possible to generically convert BER to DER without knowledge of the 465 * structure itself. However, this sufficies to handle the PKCS#7 and #12 output 466 * from NSS. 467 * 468 * It returns one on success and zero otherwise. 469 */ 470 int CBS_asn1_ber_to_der(CBS *in, uint8_t **out, size_t *out_len); 471 #endif /* LIBRESSL_INTERNAL */ 472 473 #if defined(__cplusplus) 474 } /* extern C */ 475 #endif 476 477 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 478