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 static int cbs_get_length_prefixed(CBS *cbs, CBS *out, size_t len_len) { 141 uint32_t len; 142 if (!cbs_get_u(cbs, &len, len_len)) { 143 return 0; 144 } 145 return CBS_get_bytes(cbs, out, len); 146 } 147 148 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out) { 149 return cbs_get_length_prefixed(cbs, out, 1); 150 } 151 152 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out) { 153 return cbs_get_length_prefixed(cbs, out, 2); 154 } 155 156 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out) { 157 return cbs_get_length_prefixed(cbs, out, 3); 158 } 159 160 static int cbs_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 161 size_t *out_header_len, int ber_ok) { 162 uint8_t tag, length_byte; 163 CBS header = *cbs; 164 CBS throwaway; 165 166 if (out == NULL) { 167 out = &throwaway; 168 } 169 170 if (!CBS_get_u8(&header, &tag) || 171 !CBS_get_u8(&header, &length_byte)) { 172 return 0; 173 } 174 175 if ((tag & 0x1f) == 0x1f) { 176 /* Long form tags are not supported. */ 177 return 0; 178 } 179 180 if (out_tag != NULL) { 181 *out_tag = tag; 182 } 183 184 size_t len; 185 if ((length_byte & 0x80) == 0) { 186 /* Short form length. */ 187 len = ((size_t) length_byte) + 2; 188 if (out_header_len != NULL) { 189 *out_header_len = 2; 190 } 191 } else { 192 /* Long form length. */ 193 const size_t num_bytes = length_byte & 0x7f; 194 uint32_t len32; 195 196 if (ber_ok && (tag & CBS_ASN1_CONSTRUCTED) != 0 && num_bytes == 0) { 197 /* indefinite length */ 198 if (out_header_len != NULL) { 199 *out_header_len = 2; 200 } 201 return CBS_get_bytes(cbs, out, 2); 202 } 203 204 if (num_bytes == 0 || num_bytes > 4) { 205 return 0; 206 } 207 if (!cbs_get_u(&header, &len32, num_bytes)) { 208 return 0; 209 } 210 if (len32 < 128) { 211 /* Length should have used short-form encoding. */ 212 return 0; 213 } 214 if ((len32 >> ((num_bytes-1)*8)) == 0) { 215 /* Length should have been at least one byte shorter. */ 216 return 0; 217 } 218 len = len32; 219 if (len + 2 + num_bytes < len) { 220 /* Overflow. */ 221 return 0; 222 } 223 len += 2 + num_bytes; 224 if (out_header_len != NULL) { 225 *out_header_len = 2 + num_bytes; 226 } 227 } 228 229 return CBS_get_bytes(cbs, out, len); 230 } 231 232 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 233 size_t *out_header_len) { 234 return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len, 235 0 /* DER only */); 236 } 237 238 int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 239 size_t *out_header_len) { 240 return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len, 241 1 /* BER allowed */); 242 } 243 244 static int cbs_get_asn1(CBS *cbs, CBS *out, unsigned tag_value, 245 int skip_header) { 246 size_t header_len; 247 unsigned tag; 248 CBS throwaway; 249 250 if (out == NULL) { 251 out = &throwaway; 252 } 253 254 if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) || 255 tag != tag_value) { 256 return 0; 257 } 258 259 if (skip_header && !CBS_skip(out, header_len)) { 260 assert(0); 261 return 0; 262 } 263 264 return 1; 265 } 266 267 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value) { 268 return cbs_get_asn1(cbs, out, tag_value, 1 /* skip header */); 269 } 270 271 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value) { 272 return cbs_get_asn1(cbs, out, tag_value, 0 /* include header */); 273 } 274 275 int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value) { 276 if (CBS_len(cbs) < 1) { 277 return 0; 278 } 279 return CBS_data(cbs)[0] == tag_value; 280 } 281 282 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) { 283 CBS bytes; 284 const uint8_t *data; 285 size_t i, len; 286 287 if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_INTEGER)) { 288 return 0; 289 } 290 291 *out = 0; 292 data = CBS_data(&bytes); 293 len = CBS_len(&bytes); 294 295 if (len == 0) { 296 /* An INTEGER is encoded with at least one octet. */ 297 return 0; 298 } 299 300 if ((data[0] & 0x80) != 0) { 301 /* Negative number. */ 302 return 0; 303 } 304 305 if (data[0] == 0 && len > 1 && (data[1] & 0x80) == 0) { 306 /* Extra leading zeros. */ 307 return 0; 308 } 309 310 for (i = 0; i < len; i++) { 311 if ((*out >> 56) != 0) { 312 /* Too large to represent as a uint64_t. */ 313 return 0; 314 } 315 *out <<= 8; 316 *out |= data[i]; 317 } 318 319 return 1; 320 } 321 322 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag) { 323 if (CBS_peek_asn1_tag(cbs, tag)) { 324 if (!CBS_get_asn1(cbs, out, tag)) { 325 return 0; 326 } 327 *out_present = 1; 328 } else { 329 *out_present = 0; 330 } 331 return 1; 332 } 333 334 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 335 unsigned tag) { 336 CBS child; 337 int present; 338 if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { 339 return 0; 340 } 341 if (present) { 342 if (!CBS_get_asn1(&child, out, CBS_ASN1_OCTETSTRING) || 343 CBS_len(&child) != 0) { 344 return 0; 345 } 346 } else { 347 CBS_init(out, NULL, 0); 348 } 349 if (out_present) { 350 *out_present = present; 351 } 352 return 1; 353 } 354 355 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, 356 uint64_t default_value) { 357 CBS child; 358 int present; 359 if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { 360 return 0; 361 } 362 if (present) { 363 if (!CBS_get_asn1_uint64(&child, out) || 364 CBS_len(&child) != 0) { 365 return 0; 366 } 367 } else { 368 *out = default_value; 369 } 370 return 1; 371 } 372 373 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 374 int default_value) { 375 CBS child, child2; 376 int present; 377 if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { 378 return 0; 379 } 380 if (present) { 381 uint8_t boolean; 382 383 if (!CBS_get_asn1(&child, &child2, CBS_ASN1_BOOLEAN) || 384 CBS_len(&child2) != 1 || 385 CBS_len(&child) != 0) { 386 return 0; 387 } 388 389 boolean = CBS_data(&child2)[0]; 390 if (boolean == 0) { 391 *out = 0; 392 } else if (boolean == 0xff) { 393 *out = 1; 394 } else { 395 return 0; 396 } 397 } else { 398 *out = default_value; 399 } 400 return 1; 401 } 402
