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source: vbox/trunk/src/libs/openssl-3.3.2/crypto/rsa/rsa_ossl.c

Last change on this file was 108206, checked in by vboxsync, 3 months ago

openssl-3.3.2: Exported all files to OSE and removed .scm-settings ​bugref:10757
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File size: 34.1 KB
Line 
1/*
2 * Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10/*
11 * RSA low level APIs are deprecated for public use, but still ok for
12 * internal use.
13 */
14#include "internal/deprecated.h"
15
16#include "internal/cryptlib.h"
17#include "crypto/bn.h"
18#include "rsa_local.h"
19#include "internal/constant_time.h"
20#include <openssl/evp.h>
21#include <openssl/sha.h>
22#include <openssl/hmac.h>
23
24static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
25 unsigned char *to, RSA *rsa, int padding);
26static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
27 unsigned char *to, RSA *rsa, int padding);
28static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
29 unsigned char *to, RSA *rsa, int padding);
30static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
31 unsigned char *to, RSA *rsa, int padding);
32static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
33 BN_CTX *ctx);
34static int rsa_ossl_init(RSA *rsa);
35static int rsa_ossl_finish(RSA *rsa);
36#ifdef S390X_MOD_EXP
37static int rsa_ossl_s390x_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
38 BN_CTX *ctx);
39static RSA_METHOD rsa_pkcs1_ossl_meth = {
40 "OpenSSL PKCS#1 RSA",
41 rsa_ossl_public_encrypt,
42 rsa_ossl_public_decrypt, /* signature verification */
43 rsa_ossl_private_encrypt, /* signing */
44 rsa_ossl_private_decrypt,
45 rsa_ossl_s390x_mod_exp,
46 s390x_mod_exp,
47 rsa_ossl_init,
48 rsa_ossl_finish,
49 RSA_FLAG_FIPS_METHOD, /* flags */
50 NULL,
51 0, /* rsa_sign */
52 0, /* rsa_verify */
53 NULL, /* rsa_keygen */
54 NULL /* rsa_multi_prime_keygen */
55};
56#else
57static RSA_METHOD rsa_pkcs1_ossl_meth = {
58 "OpenSSL PKCS#1 RSA",
59 rsa_ossl_public_encrypt,
60 rsa_ossl_public_decrypt, /* signature verification */
61 rsa_ossl_private_encrypt, /* signing */
62 rsa_ossl_private_decrypt,
63 rsa_ossl_mod_exp,
64 BN_mod_exp_mont, /* XXX probably we should not use Montgomery
65 * if e == 3 */
66 rsa_ossl_init,
67 rsa_ossl_finish,
68 RSA_FLAG_FIPS_METHOD, /* flags */
69 NULL,
70 0, /* rsa_sign */
71 0, /* rsa_verify */
72 NULL, /* rsa_keygen */
73 NULL /* rsa_multi_prime_keygen */
74};
75#endif
76
77static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
78
79void RSA_set_default_method(const RSA_METHOD *meth)
80{
81 default_RSA_meth = meth;
82}
83
84const RSA_METHOD *RSA_get_default_method(void)
85{
86 return default_RSA_meth;
87}
88
89const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
90{
91 return &rsa_pkcs1_ossl_meth;
92}
93
94const RSA_METHOD *RSA_null_method(void)
95{
96 return NULL;
97}
98
99static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
100 unsigned char *to, RSA *rsa, int padding)
101{
102 BIGNUM *f, *ret;
103 int i, num = 0, r = -1;
104 unsigned char *buf = NULL;
105 BN_CTX *ctx = NULL;
106
107 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
108 ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE);
109 return -1;
110 }
111
112 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
113 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
114 return -1;
115 }
116
117 /* for large moduli, enforce exponent limit */
118 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
119 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
120 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
121 return -1;
122 }
123 }
124
125 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
126 goto err;
127 BN_CTX_start(ctx);
128 f = BN_CTX_get(ctx);
129 ret = BN_CTX_get(ctx);
130 num = BN_num_bytes(rsa->n);
131 buf = OPENSSL_malloc(num);
132 if (ret == NULL || buf == NULL)
133 goto err;
134
135 switch (padding) {
136 case RSA_PKCS1_PADDING:
137 i = ossl_rsa_padding_add_PKCS1_type_2_ex(rsa->libctx, buf, num,
138 from, flen);
139 break;
140 case RSA_PKCS1_OAEP_PADDING:
141 i = ossl_rsa_padding_add_PKCS1_OAEP_mgf1_ex(rsa->libctx, buf, num,
142 from, flen, NULL, 0,
143 NULL, NULL);
144 break;
145 case RSA_NO_PADDING:
146 i = RSA_padding_add_none(buf, num, from, flen);
147 break;
148 default:
149 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
150 goto err;
151 }
152 if (i <= 0)
153 goto err;
154
155 if (BN_bin2bn(buf, num, f) == NULL)
156 goto err;
157
158 if (BN_ucmp(f, rsa->n) >= 0) {
159 /* usually the padding functions would catch this */
160 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
161 goto err;
162 }
163
164 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
165 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
166 rsa->n, ctx))
167 goto err;
168
169 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
170 rsa->_method_mod_n))
171 goto err;
172
173 /*
174 * BN_bn2binpad puts in leading 0 bytes if the number is less than
175 * the length of the modulus.
176 */
177 r = BN_bn2binpad(ret, to, num);
178 err:
179 BN_CTX_end(ctx);
180 BN_CTX_free(ctx);
181 OPENSSL_clear_free(buf, num);
182 return r;
183}
184
185static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
186{
187 BN_BLINDING *ret;
188
189 if (!CRYPTO_THREAD_read_lock(rsa->lock))
190 return NULL;
191
192 if (rsa->blinding == NULL) {
193 /*
194 * This dance with upgrading the lock from read to write will be
195 * slower in cases of a single use RSA object, but should be
196 * significantly better in multi-thread cases (e.g. servers). It's
197 * probably worth it.
198 */
199 CRYPTO_THREAD_unlock(rsa->lock);
200 if (!CRYPTO_THREAD_write_lock(rsa->lock))
201 return NULL;
202 if (rsa->blinding == NULL)
203 rsa->blinding = RSA_setup_blinding(rsa, ctx);
204 }
205
206 ret = rsa->blinding;
207 if (ret == NULL)
208 goto err;
209
210 if (BN_BLINDING_is_current_thread(ret)) {
211 /* rsa->blinding is ours! */
212
213 *local = 1;
214 } else {
215 /* resort to rsa->mt_blinding instead */
216
217 /*
218 * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
219 * BN_BLINDING is shared, meaning that accesses require locks, and
220 * that the blinding factor must be stored outside the BN_BLINDING
221 */
222 *local = 0;
223
224 if (rsa->mt_blinding == NULL) {
225 CRYPTO_THREAD_unlock(rsa->lock);
226 if (!CRYPTO_THREAD_write_lock(rsa->lock))
227 return NULL;
228 if (rsa->mt_blinding == NULL)
229 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
230 }
231 ret = rsa->mt_blinding;
232 }
233
234 err:
235 CRYPTO_THREAD_unlock(rsa->lock);
236 return ret;
237}
238
239static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
240 BN_CTX *ctx)
241{
242 if (unblind == NULL) {
243 /*
244 * Local blinding: store the unblinding factor in BN_BLINDING.
245 */
246 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
247 } else {
248 /*
249 * Shared blinding: store the unblinding factor outside BN_BLINDING.
250 */
251 int ret;
252
253 if (!BN_BLINDING_lock(b))
254 return 0;
255
256 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
257 BN_BLINDING_unlock(b);
258
259 return ret;
260 }
261}
262
263static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
264 BN_CTX *ctx)
265{
266 /*
267 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
268 * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
269 * is shared between threads, unblind must be non-null:
270 * BN_BLINDING_invert_ex will then use the local unblinding factor, and
271 * will only read the modulus from BN_BLINDING. In both cases it's safe
272 * to access the blinding without a lock.
273 */
274 BN_set_flags(f, BN_FLG_CONSTTIME);
275 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
276}
277
278/* signing */
279static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
280 unsigned char *to, RSA *rsa, int padding)
281{
282 BIGNUM *f, *ret, *res;
283 int i, num = 0, r = -1;
284 unsigned char *buf = NULL;
285 BN_CTX *ctx = NULL;
286 int local_blinding = 0;
287 /*
288 * Used only if the blinding structure is shared. A non-NULL unblind
289 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
290 * the unblinding factor outside the blinding structure.
291 */
292 BIGNUM *unblind = NULL;
293 BN_BLINDING *blinding = NULL;
294
295 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
296 goto err;
297 BN_CTX_start(ctx);
298 f = BN_CTX_get(ctx);
299 ret = BN_CTX_get(ctx);
300 num = BN_num_bytes(rsa->n);
301 buf = OPENSSL_malloc(num);
302 if (ret == NULL || buf == NULL)
303 goto err;
304
305 switch (padding) {
306 case RSA_PKCS1_PADDING:
307 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
308 break;
309 case RSA_X931_PADDING:
310 i = RSA_padding_add_X931(buf, num, from, flen);
311 break;
312 case RSA_NO_PADDING:
313 i = RSA_padding_add_none(buf, num, from, flen);
314 break;
315 default:
316 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
317 goto err;
318 }
319 if (i <= 0)
320 goto err;
321
322 if (BN_bin2bn(buf, num, f) == NULL)
323 goto err;
324
325 if (BN_ucmp(f, rsa->n) >= 0) {
326 /* usually the padding functions would catch this */
327 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
328 goto err;
329 }
330
331 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
332 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
333 rsa->n, ctx))
334 goto err;
335
336 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
337 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
338 if (blinding == NULL) {
339 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
340 goto err;
341 }
342 }
343
344 if (blinding != NULL) {
345 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
346 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
347 goto err;
348 }
349 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
350 goto err;
351 }
352
353 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
354 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
355 ((rsa->p != NULL) &&
356 (rsa->q != NULL) &&
357 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
358 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
359 goto err;
360 } else {
361 BIGNUM *d = BN_new();
362 if (d == NULL) {
363 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
364 goto err;
365 }
366 if (rsa->d == NULL) {
367 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
368 BN_free(d);
369 goto err;
370 }
371 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
372
373 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
374 rsa->_method_mod_n)) {
375 BN_free(d);
376 goto err;
377 }
378 /* We MUST free d before any further use of rsa->d */
379 BN_free(d);
380 }
381
382 if (blinding)
383 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
384 goto err;
385
386 if (padding == RSA_X931_PADDING) {
387 if (!BN_sub(f, rsa->n, ret))
388 goto err;
389 if (BN_cmp(ret, f) > 0)
390 res = f;
391 else
392 res = ret;
393 } else {
394 res = ret;
395 }
396
397 /*
398 * BN_bn2binpad puts in leading 0 bytes if the number is less than
399 * the length of the modulus.
400 */
401 r = BN_bn2binpad(res, to, num);
402 err:
403 BN_CTX_end(ctx);
404 BN_CTX_free(ctx);
405 OPENSSL_clear_free(buf, num);
406 return r;
407}
408
409static int derive_kdk(int flen, const unsigned char *from, RSA *rsa,
410 unsigned char *buf, int num, unsigned char *kdk)
411{
412 int ret = 0;
413 HMAC_CTX *hmac = NULL;
414 EVP_MD *md = NULL;
415 unsigned int md_len = SHA256_DIGEST_LENGTH;
416 unsigned char d_hash[SHA256_DIGEST_LENGTH] = {0};
417 /*
418 * because we use d as a handle to rsa->d we need to keep it local and
419 * free before any further use of rsa->d
420 */
421 BIGNUM *d = BN_new();
422
423 if (d == NULL) {
424 ERR_raise(ERR_LIB_RSA, ERR_R_CRYPTO_LIB);
425 goto err;
426 }
427 if (rsa->d == NULL) {
428 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
429 BN_free(d);
430 goto err;
431 }
432 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
433 if (BN_bn2binpad(d, buf, num) < 0) {
434 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
435 BN_free(d);
436 goto err;
437 }
438 BN_free(d);
439
440 /*
441 * we use hardcoded hash so that migrating between versions that use
442 * different hash doesn't provide a Bleichenbacher oracle:
443 * if the attacker can see that different versions return different
444 * messages for the same ciphertext, they'll know that the message is
445 * synthetically generated, which means that the padding check failed
446 */
447 md = EVP_MD_fetch(rsa->libctx, "sha256", NULL);
448 if (md == NULL) {
449 ERR_raise(ERR_LIB_RSA, ERR_R_FETCH_FAILED);
450 goto err;
451 }
452
453 if (EVP_Digest(buf, num, d_hash, NULL, md, NULL) <= 0) {
454 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
455 goto err;
456 }
457
458 hmac = HMAC_CTX_new();
459 if (hmac == NULL) {
460 ERR_raise(ERR_LIB_RSA, ERR_R_CRYPTO_LIB);
461 goto err;
462 }
463
464 if (HMAC_Init_ex(hmac, d_hash, sizeof(d_hash), md, NULL) <= 0) {
465 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
466 goto err;
467 }
468
469 if (flen < num) {
470 memset(buf, 0, num - flen);
471 if (HMAC_Update(hmac, buf, num - flen) <= 0) {
472 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
473 goto err;
474 }
475 }
476 if (HMAC_Update(hmac, from, flen) <= 0) {
477 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
478 goto err;
479 }
480
481 md_len = SHA256_DIGEST_LENGTH;
482 if (HMAC_Final(hmac, kdk, &md_len) <= 0) {
483 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
484 goto err;
485 }
486 ret = 1;
487
488 err:
489 HMAC_CTX_free(hmac);
490 EVP_MD_free(md);
491 return ret;
492}
493
494static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
495 unsigned char *to, RSA *rsa, int padding)
496{
497 BIGNUM *f, *ret;
498 int j, num = 0, r = -1;
499 unsigned char *buf = NULL;
500 unsigned char kdk[SHA256_DIGEST_LENGTH] = {0};
501 BN_CTX *ctx = NULL;
502 int local_blinding = 0;
503 /*
504 * Used only if the blinding structure is shared. A non-NULL unblind
505 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
506 * the unblinding factor outside the blinding structure.
507 */
508 BIGNUM *unblind = NULL;
509 BN_BLINDING *blinding = NULL;
510
511 /*
512 * we need the value of the private exponent to perform implicit rejection
513 */
514 if ((rsa->flags & RSA_FLAG_EXT_PKEY) && (padding == RSA_PKCS1_PADDING))
515 padding = RSA_PKCS1_NO_IMPLICIT_REJECT_PADDING;
516
517 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
518 goto err;
519 BN_CTX_start(ctx);
520 f = BN_CTX_get(ctx);
521 ret = BN_CTX_get(ctx);
522 if (ret == NULL) {
523 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
524 goto err;
525 }
526 num = BN_num_bytes(rsa->n);
527 buf = OPENSSL_malloc(num);
528 if (buf == NULL)
529 goto err;
530
531 /*
532 * This check was for equality but PGP does evil things and chops off the
533 * top '0' bytes
534 */
535 if (flen > num) {
536 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN);
537 goto err;
538 }
539
540 if (flen < 1) {
541 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_SMALL);
542 goto err;
543 }
544
545 /* make data into a big number */
546 if (BN_bin2bn(from, (int)flen, f) == NULL)
547 goto err;
548
549 if (BN_ucmp(f, rsa->n) >= 0) {
550 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
551 goto err;
552 }
553
554 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
555 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
556 rsa->n, ctx))
557 goto err;
558
559 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
560 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
561 if (blinding == NULL) {
562 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
563 goto err;
564 }
565 }
566
567 if (blinding != NULL) {
568 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
569 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
570 goto err;
571 }
572 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
573 goto err;
574 }
575
576 /* do the decrypt */
577 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
578 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
579 ((rsa->p != NULL) &&
580 (rsa->q != NULL) &&
581 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
582 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
583 goto err;
584 } else {
585 BIGNUM *d = BN_new();
586 if (d == NULL) {
587 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
588 goto err;
589 }
590 if (rsa->d == NULL) {
591 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
592 BN_free(d);
593 goto err;
594 }
595 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
596 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
597 rsa->_method_mod_n)) {
598 BN_free(d);
599 goto err;
600 }
601 /* We MUST free d before any further use of rsa->d */
602 BN_free(d);
603 }
604
605 if (blinding)
606 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
607 goto err;
608
609 /*
610 * derive the Key Derivation Key from private exponent and public
611 * ciphertext
612 */
613 if (padding == RSA_PKCS1_PADDING) {
614 if (derive_kdk(flen, from, rsa, buf, num, kdk) == 0)
615 goto err;
616 }
617
618 j = BN_bn2binpad(ret, buf, num);
619 if (j < 0)
620 goto err;
621
622 switch (padding) {
623 case RSA_PKCS1_NO_IMPLICIT_REJECT_PADDING:
624 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
625 break;
626 case RSA_PKCS1_PADDING:
627 r = ossl_rsa_padding_check_PKCS1_type_2(rsa->libctx, to, num, buf, j, num, kdk);
628 break;
629 case RSA_PKCS1_OAEP_PADDING:
630 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
631 break;
632 case RSA_NO_PADDING:
633 memcpy(to, buf, (r = j));
634 break;
635 default:
636 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
637 goto err;
638 }
639#ifndef FIPS_MODULE
640 /*
641 * This trick doesn't work in the FIPS provider because libcrypto manages
642 * the error stack. Instead we opt not to put an error on the stack at all
643 * in case of padding failure in the FIPS provider.
644 */
645 ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED);
646 err_clear_last_constant_time(1 & ~constant_time_msb(r));
647#endif
648
649 err:
650 BN_CTX_end(ctx);
651 BN_CTX_free(ctx);
652 OPENSSL_clear_free(buf, num);
653 return r;
654}
655
656/* signature verification */
657static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
658 unsigned char *to, RSA *rsa, int padding)
659{
660 BIGNUM *f, *ret;
661 int i, num = 0, r = -1;
662 unsigned char *buf = NULL;
663 BN_CTX *ctx = NULL;
664
665 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
666 ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE);
667 return -1;
668 }
669
670 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
671 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
672 return -1;
673 }
674
675 /* for large moduli, enforce exponent limit */
676 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
677 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
678 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
679 return -1;
680 }
681 }
682
683 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
684 goto err;
685 BN_CTX_start(ctx);
686 f = BN_CTX_get(ctx);
687 ret = BN_CTX_get(ctx);
688 if (ret == NULL) {
689 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
690 goto err;
691 }
692 num = BN_num_bytes(rsa->n);
693 buf = OPENSSL_malloc(num);
694 if (buf == NULL)
695 goto err;
696
697 /*
698 * This check was for equality but PGP does evil things and chops off the
699 * top '0' bytes
700 */
701 if (flen > num) {
702 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN);
703 goto err;
704 }
705
706 if (BN_bin2bn(from, flen, f) == NULL)
707 goto err;
708
709 if (BN_ucmp(f, rsa->n) >= 0) {
710 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
711 goto err;
712 }
713
714 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
715 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
716 rsa->n, ctx))
717 goto err;
718
719 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
720 rsa->_method_mod_n))
721 goto err;
722
723 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
724 if (!BN_sub(ret, rsa->n, ret))
725 goto err;
726
727 i = BN_bn2binpad(ret, buf, num);
728 if (i < 0)
729 goto err;
730
731 switch (padding) {
732 case RSA_PKCS1_PADDING:
733 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
734 break;
735 case RSA_X931_PADDING:
736 r = RSA_padding_check_X931(to, num, buf, i, num);
737 break;
738 case RSA_NO_PADDING:
739 memcpy(to, buf, (r = i));
740 break;
741 default:
742 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
743 goto err;
744 }
745 if (r < 0)
746 ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED);
747
748 err:
749 BN_CTX_end(ctx);
750 BN_CTX_free(ctx);
751 OPENSSL_clear_free(buf, num);
752 return r;
753}
754
755static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
756{
757 BIGNUM *r1, *m1, *vrfy;
758 int ret = 0, smooth = 0;
759#ifndef FIPS_MODULE
760 BIGNUM *r2, *m[RSA_MAX_PRIME_NUM - 2];
761 int i, ex_primes = 0;
762 RSA_PRIME_INFO *pinfo;
763#endif
764
765 BN_CTX_start(ctx);
766
767 r1 = BN_CTX_get(ctx);
768#ifndef FIPS_MODULE
769 r2 = BN_CTX_get(ctx);
770#endif
771 m1 = BN_CTX_get(ctx);
772 vrfy = BN_CTX_get(ctx);
773 if (vrfy == NULL)
774 goto err;
775
776#ifndef FIPS_MODULE
777 if (rsa->version == RSA_ASN1_VERSION_MULTI
778 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
779 || ex_primes > RSA_MAX_PRIME_NUM - 2))
780 goto err;
781#endif
782
783 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
784 BIGNUM *factor = BN_new();
785
786 if (factor == NULL)
787 goto err;
788
789 /*
790 * Make sure BN_mod_inverse in Montgomery initialization uses the
791 * BN_FLG_CONSTTIME flag
792 */
793 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
794 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
795 factor, ctx))
796 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
797 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
798 factor, ctx))) {
799 BN_free(factor);
800 goto err;
801 }
802#ifndef FIPS_MODULE
803 for (i = 0; i < ex_primes; i++) {
804 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
805 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
806 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
807 BN_free(factor);
808 goto err;
809 }
810 }
811#endif
812 /*
813 * We MUST free |factor| before any further use of the prime factors
814 */
815 BN_free(factor);
816
817 smooth = (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
818#ifndef FIPS_MODULE
819 && (ex_primes == 0)
820#endif
821 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
822 }
823
824 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
825 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
826 rsa->n, ctx))
827 goto err;
828
829 if (smooth) {
830 /*
831 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
832 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
833 * to limb width. So that at the very least if |I| is fully reduced,
834 * i.e. less than p*q, we can count on from-to round to perform
835 * below modulo operations on |I|. Unlike BN_mod it's constant time.
836 */
837 if (/* m1 = I moq q */
838 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
839 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
840 /* r1 = I mod p */
841 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
842 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
843 /*
844 * Use parallel exponentiations optimization if possible,
845 * otherwise fallback to two sequential exponentiations:
846 * m1 = m1^dmq1 mod q
847 * r1 = r1^dmp1 mod p
848 */
849 || !BN_mod_exp_mont_consttime_x2(m1, m1, rsa->dmq1, rsa->q,
850 rsa->_method_mod_q,
851 r1, r1, rsa->dmp1, rsa->p,
852 rsa->_method_mod_p,
853 ctx)
854 /* r1 = (r1 - m1) mod p */
855 /*
856 * bn_mod_sub_fixed_top is not regular modular subtraction,
857 * it can tolerate subtrahend to be larger than modulus, but
858 * not bit-wise wider. This makes up for uncommon q>p case,
859 * when |m1| can be larger than |rsa->p|.
860 */
861 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
862
863 /* r1 = r1 * iqmp mod p */
864 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
865 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
866 ctx)
867 /* r0 = r1 * q + m1 */
868 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
869 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
870 goto err;
871
872 goto tail;
873 }
874
875 /* compute I mod q */
876 {
877 BIGNUM *c = BN_new();
878 if (c == NULL)
879 goto err;
880 BN_with_flags(c, I, BN_FLG_CONSTTIME);
881
882 if (!BN_mod(r1, c, rsa->q, ctx)) {
883 BN_free(c);
884 goto err;
885 }
886
887 {
888 BIGNUM *dmq1 = BN_new();
889 if (dmq1 == NULL) {
890 BN_free(c);
891 goto err;
892 }
893 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
894
895 /* compute r1^dmq1 mod q */
896 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
897 rsa->_method_mod_q)) {
898 BN_free(c);
899 BN_free(dmq1);
900 goto err;
901 }
902 /* We MUST free dmq1 before any further use of rsa->dmq1 */
903 BN_free(dmq1);
904 }
905
906 /* compute I mod p */
907 if (!BN_mod(r1, c, rsa->p, ctx)) {
908 BN_free(c);
909 goto err;
910 }
911 /* We MUST free c before any further use of I */
912 BN_free(c);
913 }
914
915 {
916 BIGNUM *dmp1 = BN_new();
917 if (dmp1 == NULL)
918 goto err;
919 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
920
921 /* compute r1^dmp1 mod p */
922 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
923 rsa->_method_mod_p)) {
924 BN_free(dmp1);
925 goto err;
926 }
927 /* We MUST free dmp1 before any further use of rsa->dmp1 */
928 BN_free(dmp1);
929 }
930
931#ifndef FIPS_MODULE
932 if (ex_primes > 0) {
933 BIGNUM *di = BN_new(), *cc = BN_new();
934
935 if (cc == NULL || di == NULL) {
936 BN_free(cc);
937 BN_free(di);
938 goto err;
939 }
940
941 for (i = 0; i < ex_primes; i++) {
942 /* prepare m_i */
943 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
944 BN_free(cc);
945 BN_free(di);
946 goto err;
947 }
948
949 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
950
951 /* prepare c and d_i */
952 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
953 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
954
955 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
956 BN_free(cc);
957 BN_free(di);
958 goto err;
959 }
960 /* compute r1 ^ d_i mod r_i */
961 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
962 BN_free(cc);
963 BN_free(di);
964 goto err;
965 }
966 }
967
968 BN_free(cc);
969 BN_free(di);
970 }
971#endif
972
973 if (!BN_sub(r0, r0, m1))
974 goto err;
975 /*
976 * This will help stop the size of r0 increasing, which does affect the
977 * multiply if it optimised for a power of 2 size
978 */
979 if (BN_is_negative(r0))
980 if (!BN_add(r0, r0, rsa->p))
981 goto err;
982
983 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
984 goto err;
985
986 {
987 BIGNUM *pr1 = BN_new();
988 if (pr1 == NULL)
989 goto err;
990 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
991
992 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
993 BN_free(pr1);
994 goto err;
995 }
996 /* We MUST free pr1 before any further use of r1 */
997 BN_free(pr1);
998 }
999
1000 /*
1001 * If p < q it is occasionally possible for the correction of adding 'p'
1002 * if r0 is negative above to leave the result still negative. This can
1003 * break the private key operations: the following second correction
1004 * should *always* correct this rare occurrence. This will *never* happen
1005 * with OpenSSL generated keys because they ensure p > q [steve]
1006 */
1007 if (BN_is_negative(r0))
1008 if (!BN_add(r0, r0, rsa->p))
1009 goto err;
1010 if (!BN_mul(r1, r0, rsa->q, ctx))
1011 goto err;
1012 if (!BN_add(r0, r1, m1))
1013 goto err;
1014
1015#ifndef FIPS_MODULE
1016 /* add m_i to m in multi-prime case */
1017 if (ex_primes > 0) {
1018 BIGNUM *pr2 = BN_new();
1019
1020 if (pr2 == NULL)
1021 goto err;
1022
1023 for (i = 0; i < ex_primes; i++) {
1024 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1025 if (!BN_sub(r1, m[i], r0)) {
1026 BN_free(pr2);
1027 goto err;
1028 }
1029
1030 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
1031 BN_free(pr2);
1032 goto err;
1033 }
1034
1035 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
1036
1037 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
1038 BN_free(pr2);
1039 goto err;
1040 }
1041
1042 if (BN_is_negative(r1))
1043 if (!BN_add(r1, r1, pinfo->r)) {
1044 BN_free(pr2);
1045 goto err;
1046 }
1047 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
1048 BN_free(pr2);
1049 goto err;
1050 }
1051 if (!BN_add(r0, r0, r1)) {
1052 BN_free(pr2);
1053 goto err;
1054 }
1055 }
1056 BN_free(pr2);
1057 }
1058#endif
1059
1060 tail:
1061 if (rsa->e && rsa->n) {
1062 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
1063 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
1064 rsa->_method_mod_n))
1065 goto err;
1066 } else {
1067 bn_correct_top(r0);
1068 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
1069 rsa->_method_mod_n))
1070 goto err;
1071 }
1072 /*
1073 * If 'I' was greater than (or equal to) rsa->n, the operation will
1074 * be equivalent to using 'I mod n'. However, the result of the
1075 * verify will *always* be less than 'n' so we don't check for
1076 * absolute equality, just congruency.
1077 */
1078 if (!BN_sub(vrfy, vrfy, I))
1079 goto err;
1080 if (BN_is_zero(vrfy)) {
1081 bn_correct_top(r0);
1082 ret = 1;
1083 goto err; /* not actually error */
1084 }
1085 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
1086 goto err;
1087 if (BN_is_negative(vrfy))
1088 if (!BN_add(vrfy, vrfy, rsa->n))
1089 goto err;
1090 if (!BN_is_zero(vrfy)) {
1091 /*
1092 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
1093 * miscalculated CRT output, just do a raw (slower) mod_exp and
1094 * return that instead.
1095 */
1096
1097 BIGNUM *d = BN_new();
1098 if (d == NULL)
1099 goto err;
1100 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
1101
1102 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
1103 rsa->_method_mod_n)) {
1104 BN_free(d);
1105 goto err;
1106 }
1107 /* We MUST free d before any further use of rsa->d */
1108 BN_free(d);
1109 }
1110 }
1111 /*
1112 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
1113 * saves the day is that correction is highly unlike, and private key
1114 * operations are customarily performed on blinded message. Which means
1115 * that attacker won't observe correlation with chosen plaintext.
1116 * Secondly, remaining code would still handle it in same computational
1117 * time and even conceal memory access pattern around corrected top.
1118 */
1119 bn_correct_top(r0);
1120 ret = 1;
1121 err:
1122 BN_CTX_end(ctx);
1123 return ret;
1124}
1125
1126static int rsa_ossl_init(RSA *rsa)
1127{
1128 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
1129 return 1;
1130}
1131
1132static int rsa_ossl_finish(RSA *rsa)
1133{
1134#ifndef FIPS_MODULE
1135 int i;
1136 RSA_PRIME_INFO *pinfo;
1137
1138 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
1139 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1140 BN_MONT_CTX_free(pinfo->m);
1141 }
1142#endif
1143
1144 BN_MONT_CTX_free(rsa->_method_mod_n);
1145 BN_MONT_CTX_free(rsa->_method_mod_p);
1146 BN_MONT_CTX_free(rsa->_method_mod_q);
1147 return 1;
1148}
1149
1150#ifdef S390X_MOD_EXP
1151static int rsa_ossl_s390x_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
1152 BN_CTX *ctx)
1153{
1154 if (rsa->version != RSA_ASN1_VERSION_MULTI) {
1155 if (s390x_crt(r0, i, rsa->p, rsa->q, rsa->dmp1, rsa->dmq1, rsa->iqmp) == 1)
1156 return 1;
1157 }
1158 return rsa_ossl_mod_exp(r0, i, rsa, ctx);
1159}
1160
1161#endif
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