lib/libssl/bytestring.h

   1 /*      $OpenBSD: bytestring.h,v 1.15 2016/11/04 18:28:58 guenther 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_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The
 398  * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit
 399  * length. It returns one on success or zero on error.
 400  */
 401 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents);
 402
 403 /*
 404  * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|.
 405  * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit,
 406  * big-endian length. It returns one on success or zero on error.
 407  */
 408 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents);
 409
 410 /*
 411  * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|.
 412  * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit,
 413  * big-endian length. It returns one on success or zero on error.
 414  */
 415 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents);
 416
 417 /*
 418  * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an
 419  * ASN.1 object can be written. The |tag| argument will be used as the tag for
 420  * the object. Passing in |tag| number 31 will return in an error since only
 421  * single octet identifiers are supported. It returns one on success or zero
 422  * on error.
 423  */
 424 int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned int tag);
 425
 426 /*
 427  * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on
 428  * success and zero otherwise.
 429  */
 430 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len);
 431
 432 /*
 433  * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to
 434  * the beginning of that space. The caller must then write |len| bytes of
 435  * actual contents to |*out_data|. It returns one on success and zero
 436  * otherwise.
 437  */
 438 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len);
 439
 440 /*
 441  * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on
 442  * success and zero otherwise.
 443  */
 444 int CBB_add_u8(CBB *cbb, size_t value);
 445
 446 /*
 447  * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It
 448  * returns one on success and zero otherwise.
 449  */
 450 int CBB_add_u16(CBB *cbb, size_t value);
 451
 452 /*
 453  * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It
 454  * returns one on success and zero otherwise.
 455  */
 456 int CBB_add_u24(CBB *cbb, size_t value);
 457
 458 /*
 459  * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1|
 460  * and writes |value| in its contents. It returns one on success and zero on
 461  * error.
 462  */
 463 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value);
 464
 465 #ifdef LIBRESSL_INTERNAL
 466 /*
 467  * CBS_dup sets |out| to point to cbs's |data| and |len|.  It results in two
 468  * CBS that point to the same buffer.
 469  */
 470 void CBS_dup(const CBS *cbs, CBS *out);
 471
 472 /*
 473  * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
 474  * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
 475  * the tag number and |*out_header_len| to the length of the ASN.1 header. If
 476  * strict mode is disabled and the element has indefinite length then |*out|
 477  * will only contain the header. Each of |out|, |out_tag|, and
 478  * |out_header_len| may be NULL to ignore the value.
 479  *
 480  * Tag numbers greater than 30 are not supported (i.e. short form only).
 481  */
 482 int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned int *out_tag,
 483     size_t *out_header_len, int strict);
 484
 485 /*
 486  * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it
 487  * finds indefinite-length elements that otherwise appear to be valid DER, it
 488  * attempts to convert the DER-like data to DER and sets |*out| and
 489  * |*out_length| to describe a malloced buffer containing the DER data.
 490  * Additionally, |*in| will be advanced over the ASN.1 data.
 491  *
 492  * If it doesn't find any indefinite-length elements then it sets |*out| to
 493  * NULL and |*in| is unmodified.
 494  *
 495  * This is NOT a conversion from BER to DER.  There are many restrictions when
 496  * dealing with DER data.  This is only concerned with one: indefinite vs.
 497  * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output
 498  * from NSS.
 499  *
 500  * It returns one on success and zero otherwise.
 501  */
 502 int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len);
 503 #endif /* LIBRESSL_INTERNAL */
 504
 505 __END_HIDDEN_DECLS
 506
 507 #endif  /* OPENSSL_HEADER_BYTESTRING_H */