1 /* Copyright (c) 2014, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #include <openssl/buf.h> 16 #include <openssl/mem.h> 17 #include <openssl/bytestring.h> 18 19 #include <assert.h> 20 #include <string.h> 21 22 #include "internal.h" 23 24 25 void CBS_init(CBS *cbs, const uint8_t *data, size_t len) { 26 cbs->data = data; 27 cbs->len = len; 28 } 29 30 static int cbs_get(CBS *cbs, const uint8_t **p, size_t n) { 31 if (cbs->len < n) { 32 return 0; 33 } 34 35 *p = cbs->data; 36 cbs->data += n; 37 cbs->len -= n; 38 return 1; 39 } 40 41 int CBS_skip(CBS *cbs, size_t len) { 42 const uint8_t *dummy; 43 return cbs_get(cbs, &dummy, len); 44 } 45 46 const uint8_t *CBS_data(const CBS *cbs) { 47 return cbs->data; 48 } 49 50 size_t CBS_len(const CBS *cbs) { 51 return cbs->len; 52 } 53 54 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len) { 55 OPENSSL_free(*out_ptr); 56 *out_ptr = NULL; 57 *out_len = 0; 58 59 if (cbs->len == 0) { 60 return 1; 61 } 62 *out_ptr = BUF_memdup(cbs->data, cbs->len); 63 if (*out_ptr == NULL) { 64 return 0; 65 } 66 *out_len = cbs->len; 67 return 1; 68 } 69 70 int CBS_strdup(const CBS *cbs, char **out_ptr) { 71 if (*out_ptr != NULL) { 72 OPENSSL_free(*out_ptr); 73 } 74 *out_ptr = BUF_strndup((const char*)cbs->data, cbs->len); 75 return (*out_ptr != NULL); 76 } 77 78 int CBS_contains_zero_byte(const CBS *cbs) { 79 return memchr(cbs->data, 0, cbs->len) != NULL; 80 } 81 82 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len) { 83 if (len != cbs->len) { 84 return 0; 85 } 86 return CRYPTO_memcmp(cbs->data, data, len) == 0; 87 } 88 89 static int cbs_get_u(CBS *cbs, uint32_t *out, size_t len) { 90 uint32_t result = 0; 91 size_t i; 92 const uint8_t *data; 93 94 if (!cbs_get(cbs, &data, len)) { 95 return 0; 96 } 97 for (i = 0; i < len; i++) { 98 result <<= 8; 99 result |= data[i]; 100 } 101 *out = result; 102 return 1; 103 } 104 105 int CBS_get_u8(CBS *cbs, uint8_t *out) { 106 const uint8_t *v; 107 if (!cbs_get(cbs, &v, 1)) { 108 return 0; 109 } 110 *out = *v; 111 return 1; 112 } 113 114 int CBS_get_u16(CBS *cbs, uint16_t *out) { 115 uint32_t v; 116 if (!cbs_get_u(cbs, &v, 2)) { 117 return 0; 118 } 119 *out = v; 120 return 1; 121 } 122 123 int CBS_get_u24(CBS *cbs, uint32_t *out) { 124 return cbs_get_u(cbs, out, 3); 125 } 126 127 int CBS_get_u32(CBS *cbs, uint32_t *out) { 128 return cbs_get_u(cbs, out, 4); 129 } 130 131 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len) { 132 const uint8_t *v; 133 if (!cbs_get(cbs, &v, len)) { 134 return 0; 135 } 136 CBS_init(out, v, len); 137 return 1; 138 } 139 140 int CBS_copy_bytes(CBS *cbs, uint8_t *out, size_t len) { 141 const uint8_t *v; 142 if (!cbs_get(cbs, &v, len)) { 143 return 0; 144 } 145 memcpy(out, v, len); 146 return 1; 147 } 148 149 static int cbs_get_length_prefixed(CBS *cbs, CBS *out, size_t len_len) { 150 uint32_t len; 151 if (!cbs_get_u(cbs, &len, len_len)) { 152 return 0; 153 } 154 return CBS_get_bytes(cbs, out, len); 155 } 156 157 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out) { 158 return cbs_get_length_prefixed(cbs, out, 1); 159 } 160 161 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out) { 162 return cbs_get_length_prefixed(cbs, out, 2); 163 } 164 165 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out) { 166 return cbs_get_length_prefixed(cbs, out, 3); 167 } 168 169 static int cbs_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 170 size_t *out_header_len, int ber_ok) { 171 uint8_t tag, length_byte; 172 CBS header = *cbs; 173 CBS throwaway; 174 175 if (out == NULL) { 176 out = &throwaway; 177 } 178 179 if (!CBS_get_u8(&header, &tag) || 180 !CBS_get_u8(&header, &length_byte)) { 181 return 0; 182 } 183 184 if ((tag & 0x1f) == 0x1f) { 185 /* Long form tags are not supported. */ 186 return 0; 187 } 188 189 if (out_tag != NULL) { 190 *out_tag = tag; 191 } 192 193 size_t len; 194 if ((length_byte & 0x80) == 0) { 195 /* Short form length. */ 196 len = ((size_t) length_byte) + 2; 197 if (out_header_len != NULL) { 198 *out_header_len = 2; 199 } 200 } else { 201 /* Long form length. */ 202 const size_t num_bytes = length_byte & 0x7f; 203 uint32_t len32; 204 205 if (ber_ok && (tag & CBS_ASN1_CONSTRUCTED) != 0 && num_bytes == 0) { 206 /* indefinite length */ 207 if (out_header_len != NULL) { 208 *out_header_len = 2; 209 } 210 return CBS_get_bytes(cbs, out, 2); 211 } 212 213 if (num_bytes == 0 || num_bytes > 4) { 214 return 0; 215 } 216 if (!cbs_get_u(&header, &len32, num_bytes)) { 217 return 0; 218 } 219 if (len32 < 128) { 220 /* Length should have used short-form encoding. */ 221 return 0; 222 } 223 if ((len32 >> ((num_bytes-1)*8)) == 0) { 224 /* Length should have been at least one byte shorter. */ 225 return 0; 226 } 227 len = len32; 228 if (len + 2 + num_bytes < len) { 229 /* Overflow. */ 230 return 0; 231 } 232 len += 2 + num_bytes; 233 if (out_header_len != NULL) { 234 *out_header_len = 2 + num_bytes; 235 } 236 } 237 238 return CBS_get_bytes(cbs, out, len); 239 } 240 241 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 242 size_t *out_header_len) { 243 return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len, 244 0 /* DER only */); 245 } 246 247 int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 248 size_t *out_header_len) { 249 return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len, 250 1 /* BER allowed */); 251 } 252 253 static int cbs_get_asn1(CBS *cbs, CBS *out, unsigned tag_value, 254 int skip_header) { 255 size_t header_len; 256 unsigned tag; 257 CBS throwaway; 258 259 if (out == NULL) { 260 out = &throwaway; 261 } 262 263 if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) || 264 tag != tag_value) { 265 return 0; 266 } 267 268 if (skip_header && !CBS_skip(out, header_len)) { 269 assert(0); 270 return 0; 271 } 272 273 return 1; 274 } 275 276 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value) { 277 return cbs_get_asn1(cbs, out, tag_value, 1 /* skip header */); 278 } 279 280 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value) { 281 return cbs_get_asn1(cbs, out, tag_value, 0 /* include header */); 282 } 283 284 int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value) { 285 if (CBS_len(cbs) < 1) { 286 return 0; 287 } 288 return CBS_data(cbs)[0] == tag_value; 289 } 290 291 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) { 292 CBS bytes; 293 const uint8_t *data; 294 size_t i, len; 295 296 if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_INTEGER)) { 297 return 0; 298 } 299 300 *out = 0; 301 data = CBS_data(&bytes); 302 len = CBS_len(&bytes); 303 304 if (len == 0) { 305 /* An INTEGER is encoded with at least one octet. */ 306 return 0; 307 } 308 309 if ((data[0] & 0x80) != 0) { 310 /* Negative number. */ 311 return 0; 312 } 313 314 if (data[0] == 0 && len > 1 && (data[1] & 0x80) == 0) { 315 /* Extra leading zeros. */ 316 return 0; 317 } 318 319 for (i = 0; i < len; i++) { 320 if ((*out >> 56) != 0) { 321 /* Too large to represent as a uint64_t. */ 322 return 0; 323 } 324 *out <<= 8; 325 *out |= data[i]; 326 } 327 328 return 1; 329 } 330 331 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag) { 332 int present = 0; 333 334 if (CBS_peek_asn1_tag(cbs, tag)) { 335 if (!CBS_get_asn1(cbs, out, tag)) { 336 return 0; 337 } 338 present = 1; 339 } 340 341 if (out_present != NULL) { 342 *out_present = present; 343 } 344 345 return 1; 346 } 347 348 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 349 unsigned tag) { 350 CBS child; 351 int present; 352 if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { 353 return 0; 354 } 355 if (present) { 356 if (!CBS_get_asn1(&child, out, CBS_ASN1_OCTETSTRING) || 357 CBS_len(&child) != 0) { 358 return 0; 359 } 360 } else { 361 CBS_init(out, NULL, 0); 362 } 363 if (out_present) { 364 *out_present = present; 365 } 366 return 1; 367 } 368 369 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, 370 uint64_t default_value) { 371 CBS child; 372 int present; 373 if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { 374 return 0; 375 } 376 if (present) { 377 if (!CBS_get_asn1_uint64(&child, out) || 378 CBS_len(&child) != 0) { 379 return 0; 380 } 381 } else { 382 *out = default_value; 383 } 384 return 1; 385 } 386 387 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 388 int default_value) { 389 CBS child, child2; 390 int present; 391 if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { 392 return 0; 393 } 394 if (present) { 395 uint8_t boolean; 396 397 if (!CBS_get_asn1(&child, &child2, CBS_ASN1_BOOLEAN) || 398 CBS_len(&child2) != 1 || 399 CBS_len(&child) != 0) { 400 return 0; 401 } 402 403 boolean = CBS_data(&child2)[0]; 404 if (boolean == 0) { 405 *out = 0; 406 } else if (boolean == 0xff) { 407 *out = 1; 408 } else { 409 return 0; 410 } 411 } else { 412 *out = default_value; 413 } 414 return 1; 415 } 416
