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