1 /*
2 * Copyright 1995-2024 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
24 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
25 unsigned char *to, RSA *rsa, int padding);
26 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
27 unsigned char *to, RSA *rsa, int padding);
28 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
29 unsigned char *to, RSA *rsa, int padding);
30 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
31 unsigned char *to, RSA *rsa, int padding);
32 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
33 BN_CTX *ctx);
34 static int rsa_ossl_init(RSA *rsa);
35 static int rsa_ossl_finish(RSA *rsa);
36 #ifdef S390X_MOD_EXP
37 static int rsa_ossl_s390x_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
38 BN_CTX *ctx);
39 static 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
57 static 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
77 static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
78
RSA_set_default_method(const RSA_METHOD * meth)79 void RSA_set_default_method(const RSA_METHOD *meth)
80 {
81 default_RSA_meth = meth;
82 }
83
RSA_get_default_method(void)84 const RSA_METHOD *RSA_get_default_method(void)
85 {
86 return default_RSA_meth;
87 }
88
RSA_PKCS1_OpenSSL(void)89 const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
90 {
91 return &rsa_pkcs1_ossl_meth;
92 }
93
RSA_null_method(void)94 const RSA_METHOD *RSA_null_method(void)
95 {
96 return NULL;
97 }
98
rsa_ossl_public_encrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)99 static 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 #ifdef FIPS_MODULE
159 /*
160 * See SP800-56Br2, section 7.1.1.1
161 * RSAEP: 1 < f < (n – 1).
162 * (where f is the plaintext).
163 */
164 if (padding == RSA_NO_PADDING) {
165 BIGNUM *nminus1 = BN_CTX_get(ctx);
166
167 if (BN_ucmp(f, BN_value_one()) <= 0) {
168 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_SMALL);
169 goto err;
170 }
171 if (nminus1 == NULL
172 || BN_copy(nminus1, rsa->n) == NULL
173 || !BN_sub_word(nminus1, 1))
174 goto err;
175 if (BN_ucmp(f, nminus1) >= 0) {
176 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
177 goto err;
178 }
179 } else
180 #endif
181 {
182 if (BN_ucmp(f, rsa->n) >= 0) {
183 /* usually the padding functions would catch this */
184 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
185 goto err;
186 }
187 }
188
189 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
190 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
191 rsa->n, ctx))
192 goto err;
193
194 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
195 rsa->_method_mod_n))
196 goto err;
197
198 /*
199 * BN_bn2binpad puts in leading 0 bytes if the number is less than
200 * the length of the modulus.
201 */
202 r = BN_bn2binpad(ret, to, num);
203 err:
204 BN_CTX_end(ctx);
205 BN_CTX_free(ctx);
206 OPENSSL_clear_free(buf, num);
207 return r;
208 }
209
rsa_get_blinding(RSA * rsa,int * local,BN_CTX * ctx)210 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
211 {
212 BN_BLINDING *ret;
213
214 if (!CRYPTO_THREAD_read_lock(rsa->lock))
215 return NULL;
216
217 if (rsa->blinding == NULL) {
218 /*
219 * This dance with upgrading the lock from read to write will be
220 * slower in cases of a single use RSA object, but should be
221 * significantly better in multi-thread cases (e.g. servers). It's
222 * probably worth it.
223 */
224 CRYPTO_THREAD_unlock(rsa->lock);
225 if (!CRYPTO_THREAD_write_lock(rsa->lock))
226 return NULL;
227 if (rsa->blinding == NULL)
228 rsa->blinding = RSA_setup_blinding(rsa, ctx);
229 }
230
231 ret = rsa->blinding;
232 if (ret == NULL)
233 goto err;
234
235 if (BN_BLINDING_is_current_thread(ret)) {
236 /* rsa->blinding is ours! */
237
238 *local = 1;
239 } else {
240 /* resort to rsa->mt_blinding instead */
241
242 /*
243 * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
244 * BN_BLINDING is shared, meaning that accesses require locks, and
245 * that the blinding factor must be stored outside the BN_BLINDING
246 */
247 *local = 0;
248
249 if (rsa->mt_blinding == NULL) {
250 CRYPTO_THREAD_unlock(rsa->lock);
251 if (!CRYPTO_THREAD_write_lock(rsa->lock))
252 return NULL;
253 if (rsa->mt_blinding == NULL)
254 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
255 }
256 ret = rsa->mt_blinding;
257 }
258
259 err:
260 CRYPTO_THREAD_unlock(rsa->lock);
261 return ret;
262 }
263
rsa_blinding_convert(BN_BLINDING * b,BIGNUM * f,BIGNUM * unblind,BN_CTX * ctx)264 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
265 BN_CTX *ctx)
266 {
267 if (unblind == NULL) {
268 /*
269 * Local blinding: store the unblinding factor in BN_BLINDING.
270 */
271 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
272 } else {
273 /*
274 * Shared blinding: store the unblinding factor outside BN_BLINDING.
275 */
276 int ret;
277
278 if (!BN_BLINDING_lock(b))
279 return 0;
280
281 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
282 BN_BLINDING_unlock(b);
283
284 return ret;
285 }
286 }
287
rsa_blinding_invert(BN_BLINDING * b,BIGNUM * f,BIGNUM * unblind,BN_CTX * ctx)288 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
289 BN_CTX *ctx)
290 {
291 /*
292 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
293 * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
294 * is shared between threads, unblind must be non-null:
295 * BN_BLINDING_invert_ex will then use the local unblinding factor, and
296 * will only read the modulus from BN_BLINDING. In both cases it's safe
297 * to access the blinding without a lock.
298 */
299 BN_set_flags(f, BN_FLG_CONSTTIME);
300 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
301 }
302
303 /* signing */
rsa_ossl_private_encrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)304 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
305 unsigned char *to, RSA *rsa, int padding)
306 {
307 BIGNUM *f, *ret, *res;
308 int i, num = 0, r = -1;
309 unsigned char *buf = NULL;
310 BN_CTX *ctx = NULL;
311 int local_blinding = 0;
312 /*
313 * Used only if the blinding structure is shared. A non-NULL unblind
314 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
315 * the unblinding factor outside the blinding structure.
316 */
317 BIGNUM *unblind = NULL;
318 BN_BLINDING *blinding = NULL;
319
320 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
321 goto err;
322 BN_CTX_start(ctx);
323 f = BN_CTX_get(ctx);
324 ret = BN_CTX_get(ctx);
325 num = BN_num_bytes(rsa->n);
326 buf = OPENSSL_malloc(num);
327 if (ret == NULL || buf == NULL)
328 goto err;
329
330 switch (padding) {
331 case RSA_PKCS1_PADDING:
332 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
333 break;
334 case RSA_X931_PADDING:
335 i = RSA_padding_add_X931(buf, num, from, flen);
336 break;
337 case RSA_NO_PADDING:
338 i = RSA_padding_add_none(buf, num, from, flen);
339 break;
340 default:
341 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
342 goto err;
343 }
344 if (i <= 0)
345 goto err;
346
347 if (BN_bin2bn(buf, num, f) == NULL)
348 goto err;
349
350 if (BN_ucmp(f, rsa->n) >= 0) {
351 /* usually the padding functions would catch this */
352 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
353 goto err;
354 }
355
356 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
357 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
358 rsa->n, ctx))
359 goto err;
360
361 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
362 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
363 if (blinding == NULL) {
364 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
365 goto err;
366 }
367 }
368
369 if (blinding != NULL) {
370 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
371 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
372 goto err;
373 }
374 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
375 goto err;
376 }
377
378 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
379 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
380 ((rsa->p != NULL) &&
381 (rsa->q != NULL) &&
382 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
383 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
384 goto err;
385 } else {
386 BIGNUM *d = BN_new();
387 if (d == NULL) {
388 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
389 goto err;
390 }
391 if (rsa->d == NULL) {
392 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
393 BN_free(d);
394 goto err;
395 }
396 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
397
398 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
399 rsa->_method_mod_n)) {
400 BN_free(d);
401 goto err;
402 }
403 /* We MUST free d before any further use of rsa->d */
404 BN_free(d);
405 }
406
407 if (blinding)
408 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
409 goto err;
410
411 if (padding == RSA_X931_PADDING) {
412 if (!BN_sub(f, rsa->n, ret))
413 goto err;
414 if (BN_cmp(ret, f) > 0)
415 res = f;
416 else
417 res = ret;
418 } else {
419 res = ret;
420 }
421
422 /*
423 * BN_bn2binpad puts in leading 0 bytes if the number is less than
424 * the length of the modulus.
425 */
426 r = BN_bn2binpad(res, to, num);
427 err:
428 BN_CTX_end(ctx);
429 BN_CTX_free(ctx);
430 OPENSSL_clear_free(buf, num);
431 return r;
432 }
433
derive_kdk(int flen,const unsigned char * from,RSA * rsa,unsigned char * buf,int num,unsigned char * kdk)434 static int derive_kdk(int flen, const unsigned char *from, RSA *rsa,
435 unsigned char *buf, int num, unsigned char *kdk)
436 {
437 int ret = 0;
438 HMAC_CTX *hmac = NULL;
439 EVP_MD *md = NULL;
440 unsigned int md_len = SHA256_DIGEST_LENGTH;
441 unsigned char d_hash[SHA256_DIGEST_LENGTH] = {0};
442 /*
443 * because we use d as a handle to rsa->d we need to keep it local and
444 * free before any further use of rsa->d
445 */
446 BIGNUM *d = BN_new();
447
448 if (d == NULL) {
449 ERR_raise(ERR_LIB_RSA, ERR_R_CRYPTO_LIB);
450 goto err;
451 }
452 if (rsa->d == NULL) {
453 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
454 BN_free(d);
455 goto err;
456 }
457 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
458 if (BN_bn2binpad(d, buf, num) < 0) {
459 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
460 BN_free(d);
461 goto err;
462 }
463 BN_free(d);
464
465 /*
466 * we use hardcoded hash so that migrating between versions that use
467 * different hash doesn't provide a Bleichenbacher oracle:
468 * if the attacker can see that different versions return different
469 * messages for the same ciphertext, they'll know that the message is
470 * synthetically generated, which means that the padding check failed
471 */
472 md = EVP_MD_fetch(rsa->libctx, "sha256", NULL);
473 if (md == NULL) {
474 ERR_raise(ERR_LIB_RSA, ERR_R_FETCH_FAILED);
475 goto err;
476 }
477
478 if (EVP_Digest(buf, num, d_hash, NULL, md, NULL) <= 0) {
479 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
480 goto err;
481 }
482
483 hmac = HMAC_CTX_new();
484 if (hmac == NULL) {
485 ERR_raise(ERR_LIB_RSA, ERR_R_CRYPTO_LIB);
486 goto err;
487 }
488
489 if (HMAC_Init_ex(hmac, d_hash, sizeof(d_hash), md, NULL) <= 0) {
490 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
491 goto err;
492 }
493
494 if (flen < num) {
495 memset(buf, 0, num - flen);
496 if (HMAC_Update(hmac, buf, num - flen) <= 0) {
497 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
498 goto err;
499 }
500 }
501 if (HMAC_Update(hmac, from, flen) <= 0) {
502 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
503 goto err;
504 }
505
506 md_len = SHA256_DIGEST_LENGTH;
507 if (HMAC_Final(hmac, kdk, &md_len) <= 0) {
508 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
509 goto err;
510 }
511 ret = 1;
512
513 err:
514 HMAC_CTX_free(hmac);
515 EVP_MD_free(md);
516 return ret;
517 }
518
rsa_ossl_private_decrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)519 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
520 unsigned char *to, RSA *rsa, int padding)
521 {
522 BIGNUM *f, *ret;
523 int j, num = 0, r = -1;
524 unsigned char *buf = NULL;
525 unsigned char kdk[SHA256_DIGEST_LENGTH] = {0};
526 BN_CTX *ctx = NULL;
527 int local_blinding = 0;
528 /*
529 * Used only if the blinding structure is shared. A non-NULL unblind
530 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
531 * the unblinding factor outside the blinding structure.
532 */
533 BIGNUM *unblind = NULL;
534 BN_BLINDING *blinding = NULL;
535
536 /*
537 * we need the value of the private exponent to perform implicit rejection
538 */
539 if ((rsa->flags & RSA_FLAG_EXT_PKEY) && (padding == RSA_PKCS1_PADDING))
540 padding = RSA_PKCS1_NO_IMPLICIT_REJECT_PADDING;
541
542 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
543 goto err;
544 BN_CTX_start(ctx);
545 f = BN_CTX_get(ctx);
546 ret = BN_CTX_get(ctx);
547 if (ret == NULL) {
548 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
549 goto err;
550 }
551 num = BN_num_bytes(rsa->n);
552 buf = OPENSSL_malloc(num);
553 if (buf == NULL)
554 goto err;
555
556 /*
557 * This check was for equality but PGP does evil things and chops off the
558 * top '0' bytes
559 */
560 if (flen > num) {
561 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN);
562 goto err;
563 }
564
565 if (flen < 1) {
566 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_SMALL);
567 goto err;
568 }
569
570 /* make data into a big number */
571 if (BN_bin2bn(from, (int)flen, f) == NULL)
572 goto err;
573
574 #ifdef FIPS_MODULE
575 /*
576 * See SP800-56Br2, section 7.1.2.1
577 * RSADP: 1 < f < (n – 1)
578 * (where f is the ciphertext).
579 */
580 if (padding == RSA_NO_PADDING) {
581 BIGNUM *nminus1 = BN_CTX_get(ctx);
582
583 if (BN_ucmp(f, BN_value_one()) <= 0) {
584 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_SMALL);
585 goto err;
586 }
587 if (nminus1 == NULL
588 || BN_copy(nminus1, rsa->n) == NULL
589 || !BN_sub_word(nminus1, 1))
590 goto err;
591 if (BN_ucmp(f, nminus1) >= 0) {
592 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
593 goto err;
594 }
595 } else
596 #endif
597 {
598 if (BN_ucmp(f, rsa->n) >= 0) {
599 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
600 goto err;
601 }
602 }
603 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
604 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
605 rsa->n, ctx))
606 goto err;
607
608 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
609 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
610 if (blinding == NULL) {
611 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
612 goto err;
613 }
614 }
615
616 if (blinding != NULL) {
617 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
618 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
619 goto err;
620 }
621 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
622 goto err;
623 }
624
625 /* do the decrypt */
626 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
627 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
628 ((rsa->p != NULL) &&
629 (rsa->q != NULL) &&
630 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
631 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
632 goto err;
633 } else {
634 BIGNUM *d = BN_new();
635 if (d == NULL) {
636 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
637 goto err;
638 }
639 if (rsa->d == NULL) {
640 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
641 BN_free(d);
642 goto err;
643 }
644 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
645 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
646 rsa->_method_mod_n)) {
647 BN_free(d);
648 goto err;
649 }
650 /* We MUST free d before any further use of rsa->d */
651 BN_free(d);
652 }
653
654 if (blinding)
655 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
656 goto err;
657
658 /*
659 * derive the Key Derivation Key from private exponent and public
660 * ciphertext
661 */
662 if (padding == RSA_PKCS1_PADDING) {
663 if (derive_kdk(flen, from, rsa, buf, num, kdk) == 0)
664 goto err;
665 }
666
667 j = BN_bn2binpad(ret, buf, num);
668 if (j < 0)
669 goto err;
670
671 switch (padding) {
672 case RSA_PKCS1_NO_IMPLICIT_REJECT_PADDING:
673 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
674 break;
675 case RSA_PKCS1_PADDING:
676 r = ossl_rsa_padding_check_PKCS1_type_2(rsa->libctx, to, num, buf, j, num, kdk);
677 break;
678 case RSA_PKCS1_OAEP_PADDING:
679 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
680 break;
681 case RSA_NO_PADDING:
682 memcpy(to, buf, (r = j));
683 break;
684 default:
685 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
686 goto err;
687 }
688 #ifndef FIPS_MODULE
689 /*
690 * This trick doesn't work in the FIPS provider because libcrypto manages
691 * the error stack. Instead we opt not to put an error on the stack at all
692 * in case of padding failure in the FIPS provider.
693 */
694 ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED);
695 err_clear_last_constant_time(1 & ~constant_time_msb(r));
696 #endif
697
698 err:
699 BN_CTX_end(ctx);
700 BN_CTX_free(ctx);
701 OPENSSL_clear_free(buf, num);
702 return r;
703 }
704
705 /* signature verification */
rsa_ossl_public_decrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)706 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
707 unsigned char *to, RSA *rsa, int padding)
708 {
709 BIGNUM *f, *ret;
710 int i, num = 0, r = -1;
711 unsigned char *buf = NULL;
712 BN_CTX *ctx = NULL;
713
714 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
715 ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE);
716 return -1;
717 }
718
719 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
720 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
721 return -1;
722 }
723
724 /* for large moduli, enforce exponent limit */
725 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
726 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
727 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
728 return -1;
729 }
730 }
731
732 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
733 goto err;
734 BN_CTX_start(ctx);
735 f = BN_CTX_get(ctx);
736 ret = BN_CTX_get(ctx);
737 if (ret == NULL) {
738 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
739 goto err;
740 }
741 num = BN_num_bytes(rsa->n);
742 buf = OPENSSL_malloc(num);
743 if (buf == NULL)
744 goto err;
745
746 /*
747 * This check was for equality but PGP does evil things and chops off the
748 * top '0' bytes
749 */
750 if (flen > num) {
751 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN);
752 goto err;
753 }
754
755 if (BN_bin2bn(from, flen, f) == NULL)
756 goto err;
757
758 if (BN_ucmp(f, rsa->n) >= 0) {
759 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
760 goto err;
761 }
762
763 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
764 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
765 rsa->n, ctx))
766 goto err;
767
768 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
769 rsa->_method_mod_n))
770 goto err;
771
772 /* For X9.31: Assuming e is odd it does a 12 mod 16 test */
773 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
774 if (!BN_sub(ret, rsa->n, ret))
775 goto err;
776
777 i = BN_bn2binpad(ret, buf, num);
778 if (i < 0)
779 goto err;
780
781 switch (padding) {
782 case RSA_PKCS1_PADDING:
783 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
784 break;
785 case RSA_X931_PADDING:
786 r = RSA_padding_check_X931(to, num, buf, i, num);
787 break;
788 case RSA_NO_PADDING:
789 memcpy(to, buf, (r = i));
790 break;
791 default:
792 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
793 goto err;
794 }
795 if (r < 0)
796 ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED);
797
798 err:
799 BN_CTX_end(ctx);
800 BN_CTX_free(ctx);
801 OPENSSL_clear_free(buf, num);
802 return r;
803 }
804
rsa_ossl_mod_exp(BIGNUM * r0,const BIGNUM * I,RSA * rsa,BN_CTX * ctx)805 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
806 {
807 BIGNUM *r1, *m1, *vrfy;
808 int ret = 0, smooth = 0;
809 #ifndef FIPS_MODULE
810 BIGNUM *r2, *m[RSA_MAX_PRIME_NUM - 2];
811 int i, ex_primes = 0;
812 RSA_PRIME_INFO *pinfo;
813 #endif
814
815 BN_CTX_start(ctx);
816
817 r1 = BN_CTX_get(ctx);
818 #ifndef FIPS_MODULE
819 r2 = BN_CTX_get(ctx);
820 #endif
821 m1 = BN_CTX_get(ctx);
822 vrfy = BN_CTX_get(ctx);
823 if (vrfy == NULL)
824 goto err;
825
826 #ifndef FIPS_MODULE
827 if (rsa->version == RSA_ASN1_VERSION_MULTI
828 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
829 || ex_primes > RSA_MAX_PRIME_NUM - 2))
830 goto err;
831 #endif
832
833 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
834 BIGNUM *factor = BN_new();
835
836 if (factor == NULL)
837 goto err;
838
839 /*
840 * Make sure BN_mod_inverse in Montgomery initialization uses the
841 * BN_FLG_CONSTTIME flag
842 */
843 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
844 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
845 factor, ctx))
846 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
847 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
848 factor, ctx))) {
849 BN_free(factor);
850 goto err;
851 }
852 #ifndef FIPS_MODULE
853 for (i = 0; i < ex_primes; i++) {
854 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
855 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
856 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
857 BN_free(factor);
858 goto err;
859 }
860 }
861 #endif
862 /*
863 * We MUST free |factor| before any further use of the prime factors
864 */
865 BN_free(factor);
866
867 smooth = (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
868 #ifndef FIPS_MODULE
869 && (ex_primes == 0)
870 #endif
871 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
872 }
873
874 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
875 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
876 rsa->n, ctx))
877 goto err;
878
879 if (smooth) {
880 /*
881 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
882 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
883 * to limb width. So that at the very least if |I| is fully reduced,
884 * i.e. less than p*q, we can count on from-to round to perform
885 * below modulo operations on |I|. Unlike BN_mod it's constant time.
886 */
887 if (/* m1 = I moq q */
888 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
889 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
890 /* r1 = I mod p */
891 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
892 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
893 /*
894 * Use parallel exponentiations optimization if possible,
895 * otherwise fallback to two sequential exponentiations:
896 * m1 = m1^dmq1 mod q
897 * r1 = r1^dmp1 mod p
898 */
899 || !BN_mod_exp_mont_consttime_x2(m1, m1, rsa->dmq1, rsa->q,
900 rsa->_method_mod_q,
901 r1, r1, rsa->dmp1, rsa->p,
902 rsa->_method_mod_p,
903 ctx)
904 /* r1 = (r1 - m1) mod p */
905 /*
906 * bn_mod_sub_fixed_top is not regular modular subtraction,
907 * it can tolerate subtrahend to be larger than modulus, but
908 * not bit-wise wider. This makes up for uncommon q>p case,
909 * when |m1| can be larger than |rsa->p|.
910 */
911 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
912
913 /* r1 = r1 * iqmp mod p */
914 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
915 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
916 ctx)
917 /* r0 = r1 * q + m1 */
918 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
919 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
920 goto err;
921
922 goto tail;
923 }
924
925 /* compute I mod q */
926 {
927 BIGNUM *c = BN_new();
928 if (c == NULL)
929 goto err;
930 BN_with_flags(c, I, BN_FLG_CONSTTIME);
931
932 if (!BN_mod(r1, c, rsa->q, ctx)) {
933 BN_free(c);
934 goto err;
935 }
936
937 {
938 BIGNUM *dmq1 = BN_new();
939 if (dmq1 == NULL) {
940 BN_free(c);
941 goto err;
942 }
943 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
944
945 /* compute r1^dmq1 mod q */
946 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
947 rsa->_method_mod_q)) {
948 BN_free(c);
949 BN_free(dmq1);
950 goto err;
951 }
952 /* We MUST free dmq1 before any further use of rsa->dmq1 */
953 BN_free(dmq1);
954 }
955
956 /* compute I mod p */
957 if (!BN_mod(r1, c, rsa->p, ctx)) {
958 BN_free(c);
959 goto err;
960 }
961 /* We MUST free c before any further use of I */
962 BN_free(c);
963 }
964
965 {
966 BIGNUM *dmp1 = BN_new();
967 if (dmp1 == NULL)
968 goto err;
969 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
970
971 /* compute r1^dmp1 mod p */
972 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
973 rsa->_method_mod_p)) {
974 BN_free(dmp1);
975 goto err;
976 }
977 /* We MUST free dmp1 before any further use of rsa->dmp1 */
978 BN_free(dmp1);
979 }
980
981 #ifndef FIPS_MODULE
982 if (ex_primes > 0) {
983 BIGNUM *di = BN_new(), *cc = BN_new();
984
985 if (cc == NULL || di == NULL) {
986 BN_free(cc);
987 BN_free(di);
988 goto err;
989 }
990
991 for (i = 0; i < ex_primes; i++) {
992 /* prepare m_i */
993 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
994 BN_free(cc);
995 BN_free(di);
996 goto err;
997 }
998
999 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1000
1001 /* prepare c and d_i */
1002 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
1003 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
1004
1005 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
1006 BN_free(cc);
1007 BN_free(di);
1008 goto err;
1009 }
1010 /* compute r1 ^ d_i mod r_i */
1011 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
1012 BN_free(cc);
1013 BN_free(di);
1014 goto err;
1015 }
1016 }
1017
1018 BN_free(cc);
1019 BN_free(di);
1020 }
1021 #endif
1022
1023 if (!BN_sub(r0, r0, m1))
1024 goto err;
1025 /*
1026 * This will help stop the size of r0 increasing, which does affect the
1027 * multiply if it optimised for a power of 2 size
1028 */
1029 if (BN_is_negative(r0))
1030 if (!BN_add(r0, r0, rsa->p))
1031 goto err;
1032
1033 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
1034 goto err;
1035
1036 {
1037 BIGNUM *pr1 = BN_new();
1038 if (pr1 == NULL)
1039 goto err;
1040 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
1041
1042 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
1043 BN_free(pr1);
1044 goto err;
1045 }
1046 /* We MUST free pr1 before any further use of r1 */
1047 BN_free(pr1);
1048 }
1049
1050 /*
1051 * If p < q it is occasionally possible for the correction of adding 'p'
1052 * if r0 is negative above to leave the result still negative. This can
1053 * break the private key operations: the following second correction
1054 * should *always* correct this rare occurrence. This will *never* happen
1055 * with OpenSSL generated keys because they ensure p > q [steve]
1056 */
1057 if (BN_is_negative(r0))
1058 if (!BN_add(r0, r0, rsa->p))
1059 goto err;
1060 if (!BN_mul(r1, r0, rsa->q, ctx))
1061 goto err;
1062 if (!BN_add(r0, r1, m1))
1063 goto err;
1064
1065 #ifndef FIPS_MODULE
1066 /* add m_i to m in multi-prime case */
1067 if (ex_primes > 0) {
1068 BIGNUM *pr2 = BN_new();
1069
1070 if (pr2 == NULL)
1071 goto err;
1072
1073 for (i = 0; i < ex_primes; i++) {
1074 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1075 if (!BN_sub(r1, m[i], r0)) {
1076 BN_free(pr2);
1077 goto err;
1078 }
1079
1080 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
1081 BN_free(pr2);
1082 goto err;
1083 }
1084
1085 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
1086
1087 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
1088 BN_free(pr2);
1089 goto err;
1090 }
1091
1092 if (BN_is_negative(r1))
1093 if (!BN_add(r1, r1, pinfo->r)) {
1094 BN_free(pr2);
1095 goto err;
1096 }
1097 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
1098 BN_free(pr2);
1099 goto err;
1100 }
1101 if (!BN_add(r0, r0, r1)) {
1102 BN_free(pr2);
1103 goto err;
1104 }
1105 }
1106 BN_free(pr2);
1107 }
1108 #endif
1109
1110 tail:
1111 if (rsa->e && rsa->n) {
1112 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
1113 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
1114 rsa->_method_mod_n))
1115 goto err;
1116 } else {
1117 bn_correct_top(r0);
1118 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
1119 rsa->_method_mod_n))
1120 goto err;
1121 }
1122 /*
1123 * If 'I' was greater than (or equal to) rsa->n, the operation will
1124 * be equivalent to using 'I mod n'. However, the result of the
1125 * verify will *always* be less than 'n' so we don't check for
1126 * absolute equality, just congruency.
1127 */
1128 if (!BN_sub(vrfy, vrfy, I))
1129 goto err;
1130 if (BN_is_zero(vrfy)) {
1131 bn_correct_top(r0);
1132 ret = 1;
1133 goto err; /* not actually error */
1134 }
1135 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
1136 goto err;
1137 if (BN_is_negative(vrfy))
1138 if (!BN_add(vrfy, vrfy, rsa->n))
1139 goto err;
1140 if (!BN_is_zero(vrfy)) {
1141 /*
1142 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
1143 * miscalculated CRT output, just do a raw (slower) mod_exp and
1144 * return that instead.
1145 */
1146
1147 BIGNUM *d = BN_new();
1148 if (d == NULL)
1149 goto err;
1150 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
1151
1152 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
1153 rsa->_method_mod_n)) {
1154 BN_free(d);
1155 goto err;
1156 }
1157 /* We MUST free d before any further use of rsa->d */
1158 BN_free(d);
1159 }
1160 }
1161 /*
1162 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
1163 * saves the day is that correction is highly unlike, and private key
1164 * operations are customarily performed on blinded message. Which means
1165 * that attacker won't observe correlation with chosen plaintext.
1166 * Secondly, remaining code would still handle it in same computational
1167 * time and even conceal memory access pattern around corrected top.
1168 */
1169 bn_correct_top(r0);
1170 ret = 1;
1171 err:
1172 BN_CTX_end(ctx);
1173 return ret;
1174 }
1175
rsa_ossl_init(RSA * rsa)1176 static int rsa_ossl_init(RSA *rsa)
1177 {
1178 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
1179 return 1;
1180 }
1181
rsa_ossl_finish(RSA * rsa)1182 static int rsa_ossl_finish(RSA *rsa)
1183 {
1184 #ifndef FIPS_MODULE
1185 int i;
1186 RSA_PRIME_INFO *pinfo;
1187
1188 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
1189 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1190 BN_MONT_CTX_free(pinfo->m);
1191 }
1192 #endif
1193
1194 BN_MONT_CTX_free(rsa->_method_mod_n);
1195 BN_MONT_CTX_free(rsa->_method_mod_p);
1196 BN_MONT_CTX_free(rsa->_method_mod_q);
1197 return 1;
1198 }
1199
1200 #ifdef S390X_MOD_EXP
rsa_ossl_s390x_mod_exp(BIGNUM * r0,const BIGNUM * i,RSA * rsa,BN_CTX * ctx)1201 static int rsa_ossl_s390x_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
1202 BN_CTX *ctx)
1203 {
1204 if (rsa->version != RSA_ASN1_VERSION_MULTI) {
1205 if (s390x_crt(r0, i, rsa->p, rsa->q, rsa->dmp1, rsa->dmq1, rsa->iqmp) == 1)
1206 return 1;
1207 }
1208 return rsa_ossl_mod_exp(r0, i, rsa, ctx);
1209 }
1210
1211 #endif
1212
