crypto_rsa_openssl.c 15 KB
Newer Older
1
2
3
/* Copyright (c) 2001, Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
Nick Mathewson's avatar
Nick Mathewson committed
4
 * Copyright (c) 2007-2019, The Tor Project, Inc. */
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
/* See LICENSE for licensing information */

/**
 * \file crypto_rsa.c
 * \brief OpenSSL implementations of our RSA code.
 **/

#include "lib/crypt_ops/compat_openssl.h"
#include "lib/crypt_ops/crypto_rsa.h"
#include "lib/crypt_ops/crypto_util.h"
#include "lib/ctime/di_ops.h"
#include "lib/log/util_bug.h"
#include "lib/fs/files.h"

DISABLE_GCC_WARNING(redundant-decls)

#include <openssl/err.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/evp.h>
#include <openssl/engine.h>
#include <openssl/rand.h>
#include <openssl/bn.h>
#include <openssl/conf.h>

ENABLE_GCC_WARNING(redundant-decls)

#include "lib/log/log.h"
#include "lib/encoding/binascii.h"

#include <string.h>

/** Declaration for crypto_pk_t structure. */
struct crypto_pk_t
{
  int refs; /**< reference count, so we don't have to copy keys */
  RSA *key; /**< The key itself */
};

Nick Mathewson's avatar
Nick Mathewson committed
44
45
46
47
/** Return true iff <b>key</b> contains the private-key portion of the RSA
 * key. */
int
crypto_pk_key_is_private(const crypto_pk_t *k)
48
49
50
51
52
53
54
55
56
57
58
59
60
{
#ifdef OPENSSL_1_1_API
  if (!k || !k->key)
    return 0;

  const BIGNUM *p, *q;
  RSA_get0_factors(k->key, &p, &q);
  return p != NULL; /* XXX/yawning: Should we check q? */
#else /* !(defined(OPENSSL_1_1_API)) */
  return k && k->key && k->key->p;
#endif /* defined(OPENSSL_1_1_API) */
}

61
62
/** used by tortls.c: wrap an RSA* in a crypto_pk_t. Takes ownership of
 * its argument. */
63
crypto_pk_t *
64
crypto_new_pk_from_openssl_rsa_(RSA *rsa)
65
66
67
68
69
70
71
72
73
{
  crypto_pk_t *env;
  tor_assert(rsa);
  env = tor_malloc(sizeof(crypto_pk_t));
  env->refs = 1;
  env->key = rsa;
  return env;
}

74
/** Helper, used by tor-gencert.c.  Return a copy of the private RSA from a
75
76
 * crypto_pk_t. */
RSA *
77
crypto_pk_get_openssl_rsa_(crypto_pk_t *env)
78
{
Nick Mathewson's avatar
Nick Mathewson committed
79
  return RSAPrivateKey_dup(env->key);
80
81
82
83
84
85
}

/** used by tortls.c: get an equivalent EVP_PKEY* for a crypto_pk_t.  Iff
 * private is set, include the private-key portion of the key. Return a valid
 * pointer on success, and NULL on failure. */
MOCK_IMPL(EVP_PKEY *,
86
crypto_pk_get_openssl_evp_pkey_,(crypto_pk_t *env, int private))
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
{
  RSA *key = NULL;
  EVP_PKEY *pkey = NULL;
  tor_assert(env->key);
  if (private) {
    if (!(key = RSAPrivateKey_dup(env->key)))
      goto error;
  } else {
    if (!(key = RSAPublicKey_dup(env->key)))
      goto error;
  }
  if (!(pkey = EVP_PKEY_new()))
    goto error;
  if (!(EVP_PKEY_assign_RSA(pkey, key)))
    goto error;
  return pkey;
 error:
  if (pkey)
    EVP_PKEY_free(pkey);
  if (key)
    RSA_free(key);
  return NULL;
}

/** Allocate and return storage for a public key.  The key itself will not yet
 * be set.
 */
MOCK_IMPL(crypto_pk_t *,
crypto_pk_new,(void))
{
  RSA *rsa;

  rsa = RSA_new();
  tor_assert(rsa);
121
  return crypto_new_pk_from_openssl_rsa_(rsa);
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
}

/** Release a reference to an asymmetric key; when all the references
 * are released, free the key.
 */
void
crypto_pk_free_(crypto_pk_t *env)
{
  if (!env)
    return;

  if (--env->refs > 0)
    return;
  tor_assert(env->refs == 0);

  if (env->key)
    RSA_free(env->key);

  tor_free(env);
}

/** Generate a <b>bits</b>-bit new public/private keypair in <b>env</b>.
 * Return 0 on success, -1 on failure.
 */
MOCK_IMPL(int,
crypto_pk_generate_key_with_bits,(crypto_pk_t *env, int bits))
{
  tor_assert(env);

  if (env->key) {
    RSA_free(env->key);
    env->key = NULL;
  }

  {
    BIGNUM *e = BN_new();
    RSA *r = NULL;
    if (!e)
      goto done;
Nick Mathewson's avatar
Nick Mathewson committed
161
    if (! BN_set_word(e, TOR_RSA_EXPONENT))
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
      goto done;
    r = RSA_new();
    if (!r)
      goto done;
    if (RSA_generate_key_ex(r, bits, e, NULL) == -1)
      goto done;

    env->key = r;
    r = NULL;
  done:
    if (e)
      BN_clear_free(e);
    if (r)
      RSA_free(r);
  }

  if (!env->key) {
    crypto_openssl_log_errors(LOG_WARN, "generating RSA key");
    return -1;
  }

  return 0;
}

186
/** Return true if <b>env</b> has a valid key; false otherwise.
187
188
 */
int
189
crypto_pk_is_valid_private_key(const crypto_pk_t *env)
190
191
192
193
194
{
  int r;
  tor_assert(env);

  r = RSA_check_key(env->key);
195
  if (r <= 0) {
196
    crypto_openssl_log_errors(LOG_WARN,"checking RSA key");
197
198
199
200
    return 0;
  } else {
    return 1;
  }
201
202
203
}

/** Return true iff <b>env</b> contains a public key whose public exponent
Nick Mathewson's avatar
Nick Mathewson committed
204
 * equals TOR_RSA_EXPONENT.
205
206
 */
int
207
crypto_pk_public_exponent_ok(const crypto_pk_t *env)
208
209
210
211
212
213
214
215
216
217
218
219
{
  tor_assert(env);
  tor_assert(env->key);

  const BIGNUM *e;

#ifdef OPENSSL_1_1_API
  const BIGNUM *n, *d;
  RSA_get0_key(env->key, &n, &e, &d);
#else
  e = env->key->e;
#endif /* defined(OPENSSL_1_1_API) */
Nick Mathewson's avatar
Nick Mathewson committed
220
  return BN_is_word(e, TOR_RSA_EXPONENT);
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
}

/** Compare the public-key components of a and b.  Return less than 0
 * if a\<b, 0 if a==b, and greater than 0 if a\>b.  A NULL key is
 * considered to be less than all non-NULL keys, and equal to itself.
 *
 * Note that this may leak information about the keys through timing.
 */
int
crypto_pk_cmp_keys(const crypto_pk_t *a, const crypto_pk_t *b)
{
  int result;
  char a_is_non_null = (a != NULL) && (a->key != NULL);
  char b_is_non_null = (b != NULL) && (b->key != NULL);
  char an_argument_is_null = !a_is_non_null | !b_is_non_null;

  result = tor_memcmp(&a_is_non_null, &b_is_non_null, sizeof(a_is_non_null));
  if (an_argument_is_null)
    return result;

  const BIGNUM *a_n, *a_e;
  const BIGNUM *b_n, *b_e;

#ifdef OPENSSL_1_1_API
  const BIGNUM *a_d, *b_d;
  RSA_get0_key(a->key, &a_n, &a_e, &a_d);
  RSA_get0_key(b->key, &b_n, &b_e, &b_d);
#else
  a_n = a->key->n;
  a_e = a->key->e;
  b_n = b->key->n;
  b_e = b->key->e;
#endif /* defined(OPENSSL_1_1_API) */

  tor_assert(a_n != NULL && a_e != NULL);
  tor_assert(b_n != NULL && b_e != NULL);

  result = BN_cmp(a_n, b_n);
  if (result)
    return result;
  return BN_cmp(a_e, b_e);
}

/** Return the size of the public key modulus in <b>env</b>, in bytes. */
size_t
crypto_pk_keysize(const crypto_pk_t *env)
{
  tor_assert(env);
  tor_assert(env->key);

  return (size_t) RSA_size((RSA*)env->key);
}

/** Return the size of the public key modulus of <b>env</b>, in bits. */
int
crypto_pk_num_bits(crypto_pk_t *env)
{
  tor_assert(env);
  tor_assert(env->key);

#ifdef OPENSSL_1_1_API
  /* It's so stupid that there's no other way to check that n is valid
   * before calling RSA_bits().
   */
  const BIGNUM *n, *e, *d;
  RSA_get0_key(env->key, &n, &e, &d);
  tor_assert(n != NULL);

  return RSA_bits(env->key);
#else /* !(defined(OPENSSL_1_1_API)) */
  tor_assert(env->key->n);
  return BN_num_bits(env->key->n);
#endif /* defined(OPENSSL_1_1_API) */
}

/** Increase the reference count of <b>env</b>, and return it.
 */
crypto_pk_t *
crypto_pk_dup_key(crypto_pk_t *env)
{
  tor_assert(env);
  tor_assert(env->key);

  env->refs++;
  return env;
}

308
309
310
/** Replace dest with src (private key only).  (Dest must have a refcount
 * of 1)
 */
311
void
312
crypto_pk_assign_private(crypto_pk_t *dest, const crypto_pk_t *src)
313
314
315
316
317
318
319
{
  tor_assert(dest);
  tor_assert(dest->refs == 1);
  tor_assert(src);
  RSA_free(dest->key);
  dest->key = RSAPrivateKey_dup(src->key);
}
320
321
322
323
324
325
326
327
328
329
330
331
332

/** Replace dest with src (public key only).  (Dest must have a refcount
 * of 1)
 */
void
crypto_pk_assign_public(crypto_pk_t *dest, const crypto_pk_t *src)
{
  tor_assert(dest);
  tor_assert(dest->refs == 1);
  tor_assert(src);
  RSA_free(dest->key);
  dest->key = RSAPublicKey_dup(src->key);
}
333
334
335
336
337
338
339
340
341
342
343

/** Make a real honest-to-goodness copy of <b>env</b>, and return it.
 * Returns NULL on failure. */
crypto_pk_t *
crypto_pk_copy_full(crypto_pk_t *env)
{
  RSA *new_key;
  int privatekey = 0;
  tor_assert(env);
  tor_assert(env->key);

Nick Mathewson's avatar
Nick Mathewson committed
344
  if (crypto_pk_key_is_private(env)) {
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
    new_key = RSAPrivateKey_dup(env->key);
    privatekey = 1;
  } else {
    new_key = RSAPublicKey_dup(env->key);
  }
  if (!new_key) {
    /* LCOV_EXCL_START
     *
     * We can't cause RSA*Key_dup() to fail, so we can't really test this.
     */
    log_err(LD_CRYPTO, "Unable to duplicate a %s key: openssl failed.",
            privatekey?"private":"public");
    crypto_openssl_log_errors(LOG_ERR,
                      privatekey ? "Duplicating a private key" :
                      "Duplicating a public key");
    tor_fragile_assert();
    return NULL;
    /* LCOV_EXCL_STOP */
  }

365
  return crypto_new_pk_from_openssl_rsa_(new_key);
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
}

/** Encrypt <b>fromlen</b> bytes from <b>from</b> with the public key
 * in <b>env</b>, using the padding method <b>padding</b>.  On success,
 * write the result to <b>to</b>, and return the number of bytes
 * written.  On failure, return -1.
 *
 * <b>tolen</b> is the number of writable bytes in <b>to</b>, and must be
 * at least the length of the modulus of <b>env</b>.
 */
int
crypto_pk_public_encrypt(crypto_pk_t *env, char *to, size_t tolen,
                         const char *from, size_t fromlen, int padding)
{
  int r;
  tor_assert(env);
  tor_assert(from);
  tor_assert(to);
  tor_assert(fromlen<INT_MAX);
  tor_assert(tolen >= crypto_pk_keysize(env));

  r = RSA_public_encrypt((int)fromlen,
                         (unsigned char*)from, (unsigned char*)to,
                         env->key, crypto_get_rsa_padding(padding));
  if (r<0) {
    crypto_openssl_log_errors(LOG_WARN, "performing RSA encryption");
    return -1;
  }
  return r;
}

/** Decrypt <b>fromlen</b> bytes from <b>from</b> with the private key
 * in <b>env</b>, using the padding method <b>padding</b>.  On success,
 * write the result to <b>to</b>, and return the number of bytes
 * written.  On failure, return -1.
 *
 * <b>tolen</b> is the number of writable bytes in <b>to</b>, and must be
 * at least the length of the modulus of <b>env</b>.
 */
int
crypto_pk_private_decrypt(crypto_pk_t *env, char *to,
                          size_t tolen,
                          const char *from, size_t fromlen,
                          int padding, int warnOnFailure)
{
  int r;
  tor_assert(env);
  tor_assert(from);
  tor_assert(to);
  tor_assert(env->key);
  tor_assert(fromlen<INT_MAX);
  tor_assert(tolen >= crypto_pk_keysize(env));
  if (!crypto_pk_key_is_private(env))
    /* Not a private key */
    return -1;

  r = RSA_private_decrypt((int)fromlen,
                          (unsigned char*)from, (unsigned char*)to,
                          env->key, crypto_get_rsa_padding(padding));

  if (r<0) {
    crypto_openssl_log_errors(warnOnFailure?LOG_WARN:LOG_DEBUG,
                      "performing RSA decryption");
    return -1;
  }
  return r;
}

/** Check the signature in <b>from</b> (<b>fromlen</b> bytes long) with the
 * public key in <b>env</b>, using PKCS1 padding.  On success, write the
 * signed data to <b>to</b>, and return the number of bytes written.
 * On failure, return -1.
 *
 * <b>tolen</b> is the number of writable bytes in <b>to</b>, and must be
 * at least the length of the modulus of <b>env</b>.
 */
MOCK_IMPL(int,
crypto_pk_public_checksig,(const crypto_pk_t *env, char *to,
                           size_t tolen,
                           const char *from, size_t fromlen))
{
  int r;
  tor_assert(env);
  tor_assert(from);
  tor_assert(to);
  tor_assert(fromlen < INT_MAX);
  tor_assert(tolen >= crypto_pk_keysize(env));
  r = RSA_public_decrypt((int)fromlen,
                         (unsigned char*)from, (unsigned char*)to,
                         env->key, RSA_PKCS1_PADDING);

  if (r<0) {
    crypto_openssl_log_errors(LOG_INFO, "checking RSA signature");
    return -1;
  }
  return r;
}

/** Sign <b>fromlen</b> bytes of data from <b>from</b> with the private key in
 * <b>env</b>, using PKCS1 padding.  On success, write the signature to
 * <b>to</b>, and return the number of bytes written.  On failure, return
 * -1.
 *
 * <b>tolen</b> is the number of writable bytes in <b>to</b>, and must be
 * at least the length of the modulus of <b>env</b>.
 */
int
crypto_pk_private_sign(const crypto_pk_t *env, char *to, size_t tolen,
                       const char *from, size_t fromlen)
{
  int r;
  tor_assert(env);
  tor_assert(from);
  tor_assert(to);
  tor_assert(fromlen < INT_MAX);
  tor_assert(tolen >= crypto_pk_keysize(env));
  if (!crypto_pk_key_is_private(env))
    /* Not a private key */
    return -1;

  r = RSA_private_encrypt((int)fromlen,
                          (unsigned char*)from, (unsigned char*)to,
                          (RSA*)env->key, RSA_PKCS1_PADDING);
  if (r<0) {
    crypto_openssl_log_errors(LOG_WARN, "generating RSA signature");
    return -1;
  }
  return r;
}

/** ASN.1-encode the public portion of <b>pk</b> into <b>dest</b>.
 * Return -1 on error, or the number of characters used on success.
 */
int
crypto_pk_asn1_encode(const crypto_pk_t *pk, char *dest, size_t dest_len)
{
  int len;
  unsigned char *buf = NULL;

  len = i2d_RSAPublicKey(pk->key, &buf);
  if (len < 0 || buf == NULL)
    return -1;

  if ((size_t)len > dest_len || dest_len > SIZE_T_CEILING) {
    OPENSSL_free(buf);
    return -1;
  }
  /* We don't encode directly into 'dest', because that would be illegal
   * type-punning.  (C99 is smarter than me, C99 is smarter than me...)
   */
  memcpy(dest,buf,len);
  OPENSSL_free(buf);
  return len;
}

/** Decode an ASN.1-encoded public key from <b>str</b>; return the result on
 * success and NULL on failure.
 */
crypto_pk_t *
crypto_pk_asn1_decode(const char *str, size_t len)
{
  RSA *rsa;
  unsigned char *buf;
  const unsigned char *cp;
  cp = buf = tor_malloc(len);
  memcpy(buf,str,len);
  rsa = d2i_RSAPublicKey(NULL, &cp, len);
  tor_free(buf);
  if (!rsa) {
    crypto_openssl_log_errors(LOG_WARN,"decoding public key");
    return NULL;
  }
538
  return crypto_new_pk_from_openssl_rsa_(rsa);
539
540
}

541
542
/** ASN.1-encode the private portion of <b>pk</b> into <b>dest</b>.
 * Return -1 on error, or the number of characters used on success.
543
544
 */
int
545
546
crypto_pk_asn1_encode_private(const crypto_pk_t *pk, char *dest,
                              size_t dest_len)
547
{
548
549
  int len;
  unsigned char *buf = NULL;
550

551
552
553
  len = i2d_RSAPrivateKey(pk->key, &buf);
  if (len < 0 || buf == NULL)
    return -1;
554

555
556
557
  if ((size_t)len > dest_len || dest_len > SIZE_T_CEILING) {
    OPENSSL_free(buf);
    return -1;
558
  }
559
560
561
562
563
564
  /* We don't encode directly into 'dest', because that would be illegal
   * type-punning.  (C99 is smarter than me, C99 is smarter than me...)
   */
  memcpy(dest,buf,len);
  OPENSSL_free(buf);
  return len;
565
566
}

567
568
/** Decode an ASN.1-encoded private key from <b>str</b>; return the result on
 * success and NULL on failure.
569
570
571
 *
 * If <b>max_bits</b> is nonnegative, reject any key longer than max_bits
 * without performing any expensive validation on it.
572
573
 */
crypto_pk_t *
574
crypto_pk_asn1_decode_private(const char *str, size_t len, int max_bits)
575
{
576
577
578
579
580
581
582
  RSA *rsa;
  unsigned char *buf;
  const unsigned char *cp;
  cp = buf = tor_malloc(len);
  memcpy(buf,str,len);
  rsa = d2i_RSAPrivateKey(NULL, &cp, len);
  tor_free(buf);
583
  if (!rsa) {
584
585
586
587
588
    crypto_openssl_log_errors(LOG_WARN,"decoding private key");
    return NULL;
  }
  if (max_bits >= 0 && RSA_bits(rsa) > max_bits) {
    log_info(LD_CRYPTO, "Private key longer than expected.");
589
    return NULL;
590
  }
591
592
593
594
595
596
  crypto_pk_t *result = crypto_new_pk_from_openssl_rsa_(rsa);
  if (! crypto_pk_is_valid_private_key(result)) {
    crypto_pk_free(result);
    return NULL;
  }
  return result;
597
}