1 /*
2 * ASN.1 DER parsing
3 * Copyright (c) 2006-2014, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "includes.h"
10
11 #include "common.h"
12 #include "utils/wpabuf.h"
13 #include "asn1.h"
14
15 const struct asn1_oid asn1_sha1_oid = {
16 .oid = { 1, 3, 14, 3, 2, 26 },
17 .len = 6
18 };
19
20 const struct asn1_oid asn1_sha256_oid = {
21 .oid = { 2, 16, 840, 1, 101, 3, 4, 2, 1 },
22 .len = 9
23 };
24
25 const struct asn1_oid asn1_ec_public_key_oid = {
26 .oid = { 1, 2, 840, 10045, 2, 1 },
27 .len = 6
28 };
29
30 const struct asn1_oid asn1_prime256v1_oid = {
31 .oid = { 1, 2, 840, 10045, 3, 1, 7 },
32 .len = 7
33 };
34
35 const struct asn1_oid asn1_secp384r1_oid = {
36 .oid = { 1, 3, 132, 0, 34 },
37 .len = 5
38 };
39
40 const struct asn1_oid asn1_secp521r1_oid = {
41 .oid = { 1, 3, 132, 0, 35 },
42 .len = 5
43 };
44
45 const struct asn1_oid asn1_brainpoolP256r1_oid = {
46 .oid = { 1, 3, 36, 3, 3, 2, 8, 1, 1, 7 },
47 .len = 10
48 };
49
50 const struct asn1_oid asn1_brainpoolP384r1_oid = {
51 .oid = { 1, 3, 36, 3, 3, 2, 8, 1, 1, 11 },
52 .len = 10
53 };
54
55 const struct asn1_oid asn1_brainpoolP512r1_oid = {
56 .oid = { 1, 3, 36, 3, 3, 2, 8, 1, 1, 13 },
57 .len = 10
58 };
59
60 const struct asn1_oid asn1_aes_siv_cmac_aead_256_oid = {
61 .oid = { 1, 2, 840, 113549, 1, 9, 16, 3, 22 },
62 .len = 9
63 };
64
65 const struct asn1_oid asn1_aes_siv_cmac_aead_384_oid = {
66 .oid = { 1, 2, 840, 113549, 1, 9, 16, 3, 23 },
67 .len = 9
68 };
69
70 const struct asn1_oid asn1_aes_siv_cmac_aead_512_oid = {
71 .oid = { 1, 2, 840, 113549, 1, 9, 16, 3, 24 },
72 .len = 9
73 };
74
75 const struct asn1_oid asn1_pbkdf2_oid = {
76 .oid = { 1, 2, 840, 113549, 1, 5, 12 },
77 .len = 7
78 };
79
80 const struct asn1_oid asn1_pbkdf2_hmac_sha256_oid = {
81 .oid = { 1, 2, 840, 113549, 2, 9 },
82 .len = 6
83 };
84
85 const struct asn1_oid asn1_pbkdf2_hmac_sha384_oid = {
86 .oid = { 1, 2, 840, 113549, 2, 10 },
87 .len = 6
88 };
89
90 const struct asn1_oid asn1_pbkdf2_hmac_sha512_oid = {
91 .oid = { 1, 2, 840, 113549, 2, 11 },
92 .len = 6
93 };
94
95 const struct asn1_oid asn1_dpp_config_params_oid = {
96 .oid = { 1, 3, 6, 1, 4, 1, 40808, 1, 2, 1 },
97 .len = 10
98 };
99
100 const struct asn1_oid asn1_dpp_asymmetric_key_package_oid = {
101 .oid = { 1, 3, 6, 1, 4, 1, 40808, 1, 2, 2 },
102 .len = 10
103 };
104
105
asn1_valid_der_boolean(struct asn1_hdr * hdr)106 static int asn1_valid_der_boolean(struct asn1_hdr *hdr)
107 {
108 /* Enforce DER requirements for a single way of encoding a BOOLEAN */
109 if (hdr->length != 1) {
110 wpa_printf(MSG_DEBUG, "ASN.1: Unexpected BOOLEAN length (%u)",
111 hdr->length);
112 return 0;
113 }
114
115 if (hdr->payload[0] != 0 && hdr->payload[0] != 0xff) {
116 wpa_printf(MSG_DEBUG,
117 "ASN.1: Invalid BOOLEAN value 0x%x (DER requires 0 or 0xff)",
118 hdr->payload[0]);
119 return 0;
120 }
121
122 return 1;
123 }
124
125
asn1_valid_der(struct asn1_hdr * hdr)126 static int asn1_valid_der(struct asn1_hdr *hdr)
127 {
128 if (hdr->class != ASN1_CLASS_UNIVERSAL)
129 return 1;
130 if (hdr->tag == ASN1_TAG_BOOLEAN && !asn1_valid_der_boolean(hdr))
131 return 0;
132 if (hdr->tag == ASN1_TAG_NULL && hdr->length != 0)
133 return 0;
134
135 /* Check for allowed primitive/constructed values */
136 if (hdr->constructed &&
137 (hdr->tag == ASN1_TAG_BOOLEAN ||
138 hdr->tag == ASN1_TAG_INTEGER ||
139 hdr->tag == ASN1_TAG_NULL ||
140 hdr->tag == ASN1_TAG_OID ||
141 hdr->tag == ANS1_TAG_RELATIVE_OID ||
142 hdr->tag == ASN1_TAG_REAL ||
143 hdr->tag == ASN1_TAG_ENUMERATED ||
144 hdr->tag == ASN1_TAG_BITSTRING ||
145 hdr->tag == ASN1_TAG_OCTETSTRING ||
146 hdr->tag == ASN1_TAG_NUMERICSTRING ||
147 hdr->tag == ASN1_TAG_PRINTABLESTRING ||
148 hdr->tag == ASN1_TAG_T61STRING ||
149 hdr->tag == ASN1_TAG_VIDEOTEXSTRING ||
150 hdr->tag == ASN1_TAG_VISIBLESTRING ||
151 hdr->tag == ASN1_TAG_IA5STRING ||
152 hdr->tag == ASN1_TAG_GRAPHICSTRING ||
153 hdr->tag == ASN1_TAG_GENERALSTRING ||
154 hdr->tag == ASN1_TAG_UNIVERSALSTRING ||
155 hdr->tag == ASN1_TAG_UTF8STRING ||
156 hdr->tag == ASN1_TAG_BMPSTRING ||
157 hdr->tag == ASN1_TAG_CHARACTERSTRING ||
158 hdr->tag == ASN1_TAG_UTCTIME ||
159 hdr->tag == ASN1_TAG_GENERALIZEDTIME ||
160 hdr->tag == ASN1_TAG_TIME))
161 return 0;
162 if (!hdr->constructed &&
163 (hdr->tag == ASN1_TAG_SEQUENCE ||
164 hdr->tag == ASN1_TAG_SET))
165 return 0;
166
167 return 1;
168 }
169
170
asn1_get_next(const u8 * buf,size_t len,struct asn1_hdr * hdr)171 int asn1_get_next(const u8 *buf, size_t len, struct asn1_hdr *hdr)
172 {
173 const u8 *pos, *end;
174 u8 tmp;
175
176 os_memset(hdr, 0, sizeof(*hdr));
177 pos = buf;
178 end = buf + len;
179
180 if (pos >= end) {
181 wpa_printf(MSG_DEBUG, "ASN.1: No room for Identifier");
182 return -1;
183 }
184 hdr->identifier = *pos++;
185 hdr->class = hdr->identifier >> 6;
186 hdr->constructed = !!(hdr->identifier & (1 << 5));
187
188 if ((hdr->identifier & 0x1f) == 0x1f) {
189 size_t ext_len = 0;
190
191 hdr->tag = 0;
192 if (pos == end || (*pos & 0x7f) == 0) {
193 wpa_printf(MSG_DEBUG,
194 "ASN.1: Invalid extended tag (first octet has to be included with at least one nonzero bit for the tag value)");
195 return -1;
196 }
197 do {
198 if (pos >= end) {
199 wpa_printf(MSG_DEBUG, "ASN.1: Identifier "
200 "underflow");
201 return -1;
202 }
203 ext_len++;
204 tmp = *pos++;
205 wpa_printf(MSG_MSGDUMP, "ASN.1: Extended tag data: "
206 "0x%02x", tmp);
207 hdr->tag = (hdr->tag << 7) | (tmp & 0x7f);
208 } while (tmp & 0x80);
209 wpa_printf(MSG_MSGDUMP, "ASN.1: Extended Tag: 0x%x (len=%zu)",
210 hdr->tag, ext_len);
211 if ((hdr->class != ASN1_CLASS_PRIVATE && hdr->tag < 31) ||
212 ext_len * 7 > sizeof(hdr->tag) * 8) {
213 wpa_printf(MSG_DEBUG,
214 "ASN.1: Invalid or unsupported (too large) extended Tag: 0x%x (len=%zu)",
215 hdr->tag, ext_len);
216 return -1;
217 }
218 } else
219 hdr->tag = hdr->identifier & 0x1f;
220
221 if (pos >= end) {
222 wpa_printf(MSG_DEBUG, "ASN.1: No room for Length");
223 return -1;
224 }
225 tmp = *pos++;
226 if (tmp & 0x80) {
227 if (tmp == 0xff) {
228 wpa_printf(MSG_DEBUG, "ASN.1: Reserved length "
229 "value 0xff used");
230 return -1;
231 }
232 tmp &= 0x7f; /* number of subsequent octets */
233 hdr->length = 0;
234 if (tmp == 0 || pos == end || *pos == 0) {
235 wpa_printf(MSG_DEBUG,
236 "ASN.1: Definite long form of the length does not start with a nonzero value");
237 return -1;
238 }
239 if (tmp > 4) {
240 wpa_printf(MSG_DEBUG, "ASN.1: Too long length field");
241 return -1;
242 }
243 while (tmp--) {
244 if (pos >= end) {
245 wpa_printf(MSG_DEBUG, "ASN.1: Length "
246 "underflow");
247 return -1;
248 }
249 hdr->length = (hdr->length << 8) | *pos++;
250 }
251 if (hdr->length < 128) {
252 wpa_printf(MSG_DEBUG,
253 "ASN.1: Definite long form of the length used with too short length");
254 return -1;
255 }
256 } else {
257 /* Short form - length 0..127 in one octet */
258 hdr->length = tmp;
259 }
260
261 if (end < pos || hdr->length > (unsigned int) (end - pos)) {
262 wpa_printf(MSG_DEBUG, "ASN.1: Contents underflow");
263 return -1;
264 }
265
266 hdr->payload = pos;
267
268 if (!asn1_valid_der(hdr)) {
269 asn1_print_hdr(hdr, "ASN.1: Invalid DER encoding: ");
270 return -1;
271 }
272 return 0;
273 }
274
275
asn1_print_hdr(const struct asn1_hdr * hdr,const char * title)276 void asn1_print_hdr(const struct asn1_hdr *hdr, const char *title)
277 {
278 wpa_printf(MSG_DEBUG, "%sclass %d constructed %d tag 0x%x",
279 title, hdr->class, hdr->constructed, hdr->tag);
280 }
281
282
asn1_unexpected(const struct asn1_hdr * hdr,const char * title)283 void asn1_unexpected(const struct asn1_hdr *hdr, const char *title)
284 {
285 wpa_printf(MSG_DEBUG, "%s - found class %d constructed %d tag 0x%x",
286 title, hdr->class, hdr->constructed, hdr->tag);
287 }
288
289
asn1_parse_oid(const u8 * buf,size_t len,struct asn1_oid * oid)290 int asn1_parse_oid(const u8 *buf, size_t len, struct asn1_oid *oid)
291 {
292 const u8 *pos, *end;
293 unsigned long val;
294 u8 tmp;
295
296 os_memset(oid, 0, sizeof(*oid));
297
298 pos = buf;
299 end = buf + len;
300
301 while (pos < end) {
302 val = 0;
303
304 do {
305 if (pos >= end)
306 return -1;
307 tmp = *pos++;
308 val = (val << 7) | (tmp & 0x7f);
309 } while (tmp & 0x80);
310
311 if (oid->len >= ASN1_MAX_OID_LEN) {
312 wpa_printf(MSG_DEBUG, "ASN.1: Too long OID value");
313 return -1;
314 }
315 if (oid->len == 0) {
316 /*
317 * The first octet encodes the first two object
318 * identifier components in (X*40) + Y formula.
319 * X = 0..2.
320 */
321 oid->oid[0] = val / 40;
322 if (oid->oid[0] > 2)
323 oid->oid[0] = 2;
324 oid->oid[1] = val - oid->oid[0] * 40;
325 oid->len = 2;
326 } else
327 oid->oid[oid->len++] = val;
328 }
329
330 return 0;
331 }
332
333
asn1_get_oid(const u8 * buf,size_t len,struct asn1_oid * oid,const u8 ** next)334 int asn1_get_oid(const u8 *buf, size_t len, struct asn1_oid *oid,
335 const u8 **next)
336 {
337 struct asn1_hdr hdr;
338
339 if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0 ||
340 !asn1_is_oid(&hdr)) {
341 asn1_unexpected(&hdr, "ASN.1: Expected OID");
342 return -1;
343 }
344
345 *next = hdr.payload + hdr.length;
346
347 return asn1_parse_oid(hdr.payload, hdr.length, oid);
348 }
349
350
asn1_oid_to_str(const struct asn1_oid * oid,char * buf,size_t len)351 void asn1_oid_to_str(const struct asn1_oid *oid, char *buf, size_t len)
352 {
353 char *pos = buf;
354 size_t i;
355 int ret;
356
357 if (len == 0)
358 return;
359
360 buf[0] = '\0';
361
362 for (i = 0; i < oid->len; i++) {
363 ret = os_snprintf(pos, buf + len - pos,
364 "%s%lu",
365 i == 0 ? "" : ".", oid->oid[i]);
366 if (os_snprintf_error(buf + len - pos, ret))
367 break;
368 pos += ret;
369 }
370 buf[len - 1] = '\0';
371 }
372
373
rotate_bits(u8 octet)374 static u8 rotate_bits(u8 octet)
375 {
376 int i;
377 u8 res;
378
379 res = 0;
380 for (i = 0; i < 8; i++) {
381 res <<= 1;
382 if (octet & 1)
383 res |= 1;
384 octet >>= 1;
385 }
386
387 return res;
388 }
389
390
asn1_bit_string_to_long(const u8 * buf,size_t len)391 unsigned long asn1_bit_string_to_long(const u8 *buf, size_t len)
392 {
393 unsigned long val = 0;
394 const u8 *pos = buf;
395
396 /* BER requires that unused bits are zero, so we can ignore the number
397 * of unused bits */
398 pos++;
399
400 if (len >= 2)
401 val |= rotate_bits(*pos++);
402 if (len >= 3)
403 val |= ((unsigned long) rotate_bits(*pos++)) << 8;
404 if (len >= 4)
405 val |= ((unsigned long) rotate_bits(*pos++)) << 16;
406 if (len >= 5)
407 val |= ((unsigned long) rotate_bits(*pos++)) << 24;
408 if (len >= 6)
409 wpa_printf(MSG_DEBUG, "X509: %s - some bits ignored "
410 "(BIT STRING length %lu)",
411 __func__, (unsigned long) len);
412
413 return val;
414 }
415
416
asn1_oid_equal(const struct asn1_oid * a,const struct asn1_oid * b)417 int asn1_oid_equal(const struct asn1_oid *a, const struct asn1_oid *b)
418 {
419 size_t i;
420
421 if (a->len != b->len)
422 return 0;
423
424 for (i = 0; i < a->len; i++) {
425 if (a->oid[i] != b->oid[i])
426 return 0;
427 }
428
429 return 1;
430 }
431
432
asn1_get_integer(const u8 * buf,size_t len,int * integer,const u8 ** next)433 int asn1_get_integer(const u8 *buf, size_t len, int *integer, const u8 **next)
434 {
435 struct asn1_hdr hdr;
436 size_t left;
437 const u8 *pos;
438 int value;
439
440 if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0 ||
441 !asn1_is_integer(&hdr)) {
442 asn1_unexpected(&hdr, "ASN.1: Expected INTEGER");
443 return -1;
444 }
445
446 *next = hdr.payload + hdr.length;
447 pos = hdr.payload;
448 left = hdr.length;
449 if (left > sizeof(value)) {
450 wpa_printf(MSG_DEBUG, "ASN.1: Too large INTEGER (len %u)",
451 hdr.length);
452 return -1;
453 }
454 value = 0;
455 while (left) {
456 value <<= 8;
457 value |= *pos++;
458 left--;
459 }
460
461 *integer = value;
462 return 0;
463 }
464
465
asn1_get_sequence(const u8 * buf,size_t len,struct asn1_hdr * hdr,const u8 ** next)466 int asn1_get_sequence(const u8 *buf, size_t len, struct asn1_hdr *hdr,
467 const u8 **next)
468 {
469 if (asn1_get_next(buf, len, hdr) < 0 || !asn1_is_sequence(hdr)) {
470 asn1_unexpected(hdr, "ASN.1: Expected SEQUENCE");
471 return -1;
472 }
473
474 if (next)
475 *next = hdr->payload + hdr->length;
476 return 0;
477 }
478
479
asn1_get_alg_id(const u8 * buf,size_t len,struct asn1_oid * oid,const u8 ** params,size_t * params_len,const u8 ** next)480 int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
481 const u8 **params, size_t *params_len, const u8 **next)
482 {
483 const u8 *pos = buf, *end = buf + len;
484 struct asn1_hdr hdr;
485
486 /*
487 * AlgorithmIdentifier ::= SEQUENCE {
488 * algorithm OBJECT IDENTIFIER,
489 * parameters ANY DEFINED BY algorithm OPTIONAL}
490 */
491 if (asn1_get_sequence(pos, end - pos, &hdr, next) < 0 ||
492 asn1_get_oid(hdr.payload, hdr.length, oid, &pos) < 0)
493 return -1;
494
495 if (params && params_len) {
496 *params = pos;
497 *params_len = hdr.payload + hdr.length - pos;
498 }
499
500 return 0;
501 }
502
503
asn1_put_integer(struct wpabuf * buf,int val)504 void asn1_put_integer(struct wpabuf *buf, int val)
505 {
506 u8 bin[4];
507 int zeros;
508
509 WPA_PUT_BE32(bin, val);
510 zeros = 0;
511 while (zeros < 3 && bin[zeros] == 0)
512 zeros++;
513 wpabuf_put_u8(buf, ASN1_TAG_INTEGER);
514 wpabuf_put_u8(buf, 4 - zeros);
515 wpabuf_put_data(buf, &bin[zeros], 4 - zeros);
516 }
517
518
asn1_put_len(struct wpabuf * buf,size_t len)519 static void asn1_put_len(struct wpabuf *buf, size_t len)
520 {
521 if (len <= 0x7f) {
522 wpabuf_put_u8(buf, len);
523 } else if (len <= 0xff) {
524 wpabuf_put_u8(buf, 0x80 | 1);
525 wpabuf_put_u8(buf, len);
526 } else if (len <= 0xffff) {
527 wpabuf_put_u8(buf, 0x80 | 2);
528 wpabuf_put_be16(buf, len);
529 } else if (len <= 0xffffff) {
530 wpabuf_put_u8(buf, 0x80 | 3);
531 wpabuf_put_be24(buf, len);
532 } else {
533 wpabuf_put_u8(buf, 0x80 | 4);
534 wpabuf_put_be32(buf, len);
535 }
536 }
537
538
asn1_put_octet_string(struct wpabuf * buf,const struct wpabuf * val)539 void asn1_put_octet_string(struct wpabuf *buf, const struct wpabuf *val)
540 {
541 wpabuf_put_u8(buf, ASN1_TAG_OCTETSTRING);
542 asn1_put_len(buf, wpabuf_len(val));
543 wpabuf_put_buf(buf, val);
544 }
545
546
asn1_put_oid(struct wpabuf * buf,const struct asn1_oid * oid)547 void asn1_put_oid(struct wpabuf *buf, const struct asn1_oid *oid)
548 {
549 u8 *len;
550 size_t i;
551
552 if (oid->len < 2)
553 return;
554 wpabuf_put_u8(buf, ASN1_TAG_OID);
555 len = wpabuf_put(buf, 1);
556 wpabuf_put_u8(buf, 40 * oid->oid[0] + oid->oid[1]);
557 for (i = 2; i < oid->len; i++) {
558 unsigned long val = oid->oid[i];
559 u8 bytes[8];
560 int idx = 0;
561
562 while (val) {
563 bytes[idx] = (idx ? 0x80 : 0x00) | (val & 0x7f);
564 idx++;
565 val >>= 7;
566 }
567 if (idx == 0) {
568 bytes[idx] = 0;
569 idx = 1;
570 }
571 while (idx > 0) {
572 idx--;
573 wpabuf_put_u8(buf, bytes[idx]);
574 }
575 }
576 *len = (u8 *) wpabuf_put(buf, 0) - len - 1;
577 }
578
579
asn1_put_hdr(struct wpabuf * buf,u8 class,int constructed,u8 tag,size_t len)580 void asn1_put_hdr(struct wpabuf *buf, u8 class, int constructed, u8 tag,
581 size_t len)
582 {
583 wpabuf_put_u8(buf, class << 6 | (constructed ? 0x20 : 0x00) | tag);
584 asn1_put_len(buf, len);
585 }
586
587
asn1_put_sequence(struct wpabuf * buf,const struct wpabuf * payload)588 void asn1_put_sequence(struct wpabuf *buf, const struct wpabuf *payload)
589 {
590 asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 1, ASN1_TAG_SEQUENCE,
591 wpabuf_len(payload));
592 wpabuf_put_buf(buf, payload);
593 }
594
595
asn1_put_set(struct wpabuf * buf,const struct wpabuf * payload)596 void asn1_put_set(struct wpabuf *buf, const struct wpabuf *payload)
597 {
598 asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 1, ASN1_TAG_SET,
599 wpabuf_len(payload));
600 wpabuf_put_buf(buf, payload);
601 }
602
603
asn1_put_utf8string(struct wpabuf * buf,const char * val)604 void asn1_put_utf8string(struct wpabuf *buf, const char *val)
605 {
606 asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 0, ASN1_TAG_UTF8STRING,
607 os_strlen(val));
608 wpabuf_put_str(buf, val);
609 }
610
611
asn1_build_alg_id(const struct asn1_oid * oid,const struct wpabuf * params)612 struct wpabuf * asn1_build_alg_id(const struct asn1_oid *oid,
613 const struct wpabuf *params)
614 {
615 struct wpabuf *buf;
616 size_t len;
617
618 /*
619 * AlgorithmIdentifier ::= SEQUENCE {
620 * algorithm OBJECT IDENTIFIER,
621 * parameters ANY DEFINED BY algorithm OPTIONAL}
622 */
623
624 len = 100;
625 if (params)
626 len += wpabuf_len(params);
627 buf = wpabuf_alloc(len);
628 if (!buf)
629 return NULL;
630 asn1_put_oid(buf, oid);
631 if (params)
632 wpabuf_put_buf(buf, params);
633 return asn1_encaps(buf, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
634 }
635
636
asn1_encaps(struct wpabuf * buf,u8 class,u8 tag)637 struct wpabuf * asn1_encaps(struct wpabuf *buf, u8 class, u8 tag)
638 {
639 struct wpabuf *res;
640
641 if (!buf)
642 return NULL;
643 res = wpabuf_alloc(10 + wpabuf_len(buf));
644 if (res) {
645 asn1_put_hdr(res, class, 1, tag, wpabuf_len(buf));
646 wpabuf_put_buf(res, buf);
647 }
648 wpabuf_clear_free(buf);
649 return res;
650 }
651