summaryrefslogtreecommitdiff
path: root/client/pkcs12.c
blob: 376c27bc2daddab63d63a373de0442768f004608 (plain)
1
2
3
4
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
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
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
121
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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
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
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
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
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
/*

  Copyright (c) 2009-2011 Samuel Lidén Borell <samuel@kodafritt.se>
  Copyright (c) 2010 Marcus Carlson <marcus@mejlamej.nu>
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.

*/

#define _BSD_SOURCE 1

#include <limits.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/pkcs12.h>
#include <openssl/rand.h>
#include <openssl/safestack.h>

typedef struct PKCS12Token PKCS12Token;
#define TokenType PKCS12Token

#include "../common/defines.h"
#include "certutil.h"
#include "misc.h"
#include "platform.h"
#include "request.h"
#include "backend_private.h"

typedef struct {
    int refCount;
    PKCS12 *data;
} SharedPKCS12;

struct PKCS12Token {
    Token base;
    
    SharedPKCS12 *sharedP12;
    int p12Index;
    const X509_NAME *subjectName;
};

static bool _backend_init(Backend *backend) {
    OpenSSL_add_all_algorithms();
    //listTokens(backend);
    return true;
}

static void _backend_free(Backend *backend) {
    EVP_cleanup();
}

/**
 * Parses a P12 file and returns a parsed representation of the file, with
 * a reference count so it can be shared by multiple tokens.
 */
static SharedPKCS12 *pkcs12_parse(const char *p12Data, int p12Length) {
    const unsigned char *temp = (const unsigned char*)p12Data;
    PKCS12 *data;
    
    // Parse P12 data
    data = d2i_PKCS12(NULL, &temp, p12Length);
    if (!data) return NULL;
    
    // Create a reference counted object
    SharedPKCS12 *sharedP12 = malloc(sizeof(SharedPKCS12));
    if (!sharedP12) {
        PKCS12_free(data);
        return NULL;
    }
    sharedP12->refCount = 1;
    sharedP12->data = data;
    
    return sharedP12;
}

/**
 * Releases a shared PKCS12 object. If nobody else is using the object then
 * it's freed.
 */
static void pkcs12_release(SharedPKCS12 *sharedP12) {
    if (--sharedP12->refCount == 0) {
        // We're the last reference holder to release the P12
        PKCS12_free(sharedP12->data);
        free(sharedP12);
    }
}

static EVP_PKEY *getPrivateKey(PKCS12 *p12, X509 *x509, const char* pass) {
    // Extract all PKCS7 safes
    STACK_OF(PKCS7) *pkcs7s = PKCS12_unpack_authsafes(p12);
    if (!pkcs7s) {
        certutil_updateErrorString();
        return NULL;
    }
    
    // For each PKCS7 safe
    int nump = sk_PKCS7_num(pkcs7s);
    for (int p = 0; p < nump; p++) {
        PKCS7 *p7 = sk_PKCS7_value(pkcs7s, p);
        if (!p7) continue;
        STACK_OF(PKCS12_SAFEBAG) *safebags = PKCS12_unpack_p7data(p7);
        if (!safebags) continue;
        
        // For each PKCS12 safebag
        int numb = sk_PKCS12_SAFEBAG_num(safebags);
        for (int i = 0; i < numb; i++) {
            PKCS12_SAFEBAG *bag = sk_PKCS12_SAFEBAG_value(safebags, i);
            if (!bag) continue;
            
            switch (M_PKCS12_bag_type(bag)) {
                case NID_pkcs8ShroudedKeyBag:;
                    // Encrypted key
                    PKCS8_PRIV_KEY_INFO *p8 = PKCS12_decrypt_skey(bag, pass, strlen(pass));
                    
                    if (p8) {
                        EVP_PKEY *pk = EVP_PKCS82PKEY(p8);
                        PKCS8_PRIV_KEY_INFO_free(p8);
                        if (!pk) break; // out of switch
                        
                        if (X509_check_private_key(x509, pk) > 0) {
                            sk_PKCS12_SAFEBAG_pop_free(safebags, PKCS12_SAFEBAG_free);
                            sk_PKCS7_pop_free(pkcs7s, PKCS7_free);
                            return pk;
                        }
                        EVP_PKEY_free(pk);
                    }
                    break;
            }
        }
        
        sk_PKCS12_SAFEBAG_pop_free(safebags, PKCS12_SAFEBAG_free);
    }
    
    sk_PKCS7_pop_free(pkcs7s, PKCS7_free);
    return NULL;
}

/**
 * Returns a list of all x509 certificates in a PKCS12 object.
 */
static STACK_OF(X509) *pkcs12_listCerts(PKCS12 *p12) {
    STACK_OF(X509) *x509s = sk_X509_new_null();
    if (!x509s) return NULL;
    
    // Extract all PKCS7 safes
    STACK_OF(PKCS7) *pkcs7s = PKCS12_unpack_authsafes(p12);
    if (!pkcs7s) {
        certutil_updateErrorString();
        sk_X509_free(x509s);
        return NULL;
    }
    
    // For each PKCS7 safe
    int nump = sk_PKCS7_num(pkcs7s);
    for (int p = 0; p < nump; p++) {
        PKCS7 *p7 = sk_PKCS7_value(pkcs7s, p);
        if (!p7) continue;
        STACK_OF(PKCS12_SAFEBAG) *safebags = PKCS12_unpack_p7data(p7);
        if (!safebags) {
            certutil_updateErrorString();
            continue;
        }
        
        // For each PKCS12 safebag
        int numb = sk_PKCS12_SAFEBAG_num(safebags);
        for (int i = 0; i < numb; i++) {
            PKCS12_SAFEBAG *bag = sk_PKCS12_SAFEBAG_value(safebags, i);
            if (!bag) continue;
            
            if (M_PKCS12_bag_type(bag) == NID_certBag) {
                // Extract x509 cert
                X509 *x509 = PKCS12_certbag2x509(bag);
                if (x509 == NULL) {
                    certutil_updateErrorString();
                } else {
                    sk_X509_push(x509s, x509);
                }
            }
        }
        
        sk_PKCS12_SAFEBAG_pop_free(safebags, PKCS12_SAFEBAG_free);
    }
    
    sk_PKCS7_pop_free(pkcs7s, PKCS7_free);
    return x509s;
}

/**
 * Creates a PKCS12 Token structure.
 */
static PKCS12Token *createToken(const Backend *backend, SharedPKCS12 *sharedP12,
                                X509_NAME *id, void *tag) {
    if (!sharedP12 || !id) return NULL;
    PKCS12Token *token = calloc(1, sizeof(PKCS12Token));
    if (!token) return NULL;
    token->base.backend = backend;
    token->base.status = TokenStatus_NeedPassword;
    token->base.displayName = certutil_getDisplayNameFromDN(id);
    token->base.tag = tag;
    token->sharedP12 = sharedP12;
    token->subjectName = id;
    sharedP12->refCount++;
    return token;
}

static void _backend_freeToken(PKCS12Token *token) {
    pkcs12_release(token->sharedP12);
    free(token);
}

/**
 * Adds all subjects in a PKCS12 files and notifies the frontend of them.
 */
static TokenError _backend_addFile(Backend *backend,
                                   const char *data, size_t length,
                                   void *tag) {
    SharedPKCS12 *p12 = pkcs12_parse(data, length);
    if (!p12) return TokenError_BadFile;
    
    STACK_OF(X509) *certList = pkcs12_listCerts(p12->data);
    if (!certList) {
        pkcs12_release(p12);
        return TokenError_Unknown;
    }
    
    int certCount = sk_X509_num(certList);
    for (int i = 0; i < certCount; i++) {
        X509 *x = sk_X509_value(certList, i);
        
        if (!certutil_hasKeyUsage(x, backend->notifier->keyUsage)) goto dontAddCert;
        
        X509_NAME *id = X509_get_subject_name(x);
        if (!certutil_matchSubjectFilter(backend->notifier->subjectFilter, id))
            goto dontAddCert;
        
        PKCS12Token *token = createToken(backend, p12, id, tag);
        if (token) {
            backend->notifier->notifyFunction((Token*)token, TokenChange_Added);
            continue;
        }
        
      dontAddCert:
        X509_free(x);
    }
    
    pkcs12_release(p12);
    return TokenError_Success;
}

/**
 * Returns a list of DER-BASE64 encoded certificates, from the subject
 * to the root CA.
 */
static TokenError _backend_getBase64Chain(const PKCS12Token *token,
                                          char ***certs, size_t *count) {
    
    STACK_OF(X509) *certList = pkcs12_listCerts(token->sharedP12->data);
    if (!certList) return TokenError_Unknown;
    
    X509 *cert = certutil_findCert(certList, token->subjectName,
                                   token->base.backend->notifier->keyUsage,
                                   false);
    if (!cert) {
        sk_X509_pop_free(certList, X509_free);
        return TokenError_Unknown;
    }
    
    *count = 0;
    *certs = NULL;
    if (!certutil_addToList(certs, count, cert)) goto error;
    
    X509_NAME *issuer = X509_get_issuer_name(cert);
    while (issuer != NULL) {
        cert = certutil_findCert(certList, issuer, KeyUsage_Issuing, false);
        if (!cert) break;
        
        issuer = X509_get_issuer_name(cert);
        
        if (!certutil_addToList(certs, count, cert)) goto error;
    }
    
    sk_X509_pop_free(certList, X509_free);
    return TokenError_Success;
    
  error:
    certutil_freeList(certs, count);
    return TokenError_Unknown;
}

static TokenError _backend_sign(PKCS12Token *token,
                                const char *message, size_t messagelen,
                                char **signature, size_t *siglen) {
    
    if (!message || !signature || !siglen) {
        assert(false);
        return TokenError_Unknown;
    }
    
    if (messagelen >= UINT_MAX) return TokenError_MessageTooLong;
    
    // Find the certificate for the token
    STACK_OF(X509) *certList = pkcs12_listCerts(token->sharedP12->data);
    if (!certList) return TokenError_Unknown;
    
    X509 *cert = certutil_findCert(certList, token->subjectName,
                                   token->base.backend->notifier->keyUsage,
                                   false);
    if (!cert) {
        sk_X509_pop_free(certList, X509_free);
        return TokenError_Unknown;
    }
    
    // Get the corresponding private key
    EVP_PKEY *key = getPrivateKey(token->sharedP12->data, cert,
                                  token->base.password);
    sk_X509_pop_free(certList, X509_free);
    
    if (!key) return TokenError_BadPassword;
    
    // Sign with the default crypto with SHA1
    unsigned int sig_len = EVP_PKEY_size(key);
    *siglen = sig_len;
    *signature = malloc(sig_len);
    
    EVP_MD_CTX sig_ctx;
    EVP_MD_CTX_init(&sig_ctx);
    bool success = (EVP_SignInit(&sig_ctx, EVP_sha1()) &&
                    EVP_SignUpdate(&sig_ctx, message, messagelen) &&
                    EVP_SignFinal(&sig_ctx, (unsigned char*)*signature,
                                  &sig_len, key));
    EVP_MD_CTX_cleanup(&sig_ctx);
    EVP_PKEY_free(key);
    *siglen = sig_len;
    
    if (success) {
        return TokenError_Success;
    } else {
        certutil_updateErrorString();
        free(*signature);
        return TokenError_SignatureFailure;
    }
}

typedef struct CertReq {
    struct CertReq *next;
    
    const RegutilPKCS10 *pkcs10;
    EVP_PKEY *privkey;
    RSA *rsa;
    X509_REQ *x509;
} CertReq;

// This is just what Nexus Personal uses
#define MAC_ITER 8192
#define ENC_ITER 8192
#define ENC_NID NID_pbe_WithSHA1And3_Key_TripleDES_CBC

// Used to implement same-origin checks in CreateRequest/StoreCertificates
#define OID_OWNING_HOST "2.25.30775131415393438240374622843663926555"

/**
 * Adds a key usage extension to the list of extensions in a request.
 */
static X509_EXTENSION *makeKeyUsageExt(KeyUsage keyUsage) {
    char *ku_str;
    switch (keyUsage) {
        case KeyUsage_Signing:
            ku_str = "nonRepudiation";
            break;
        case KeyUsage_Authentication:
            ku_str = "digitalSignature";
            break;
        default:
            ku_str = NULL;
    }
    return X509V3_EXT_conf_nid(NULL, NULL, NID_key_usage, ku_str);
}

static TokenError saveKeys(const CertReq *reqs, const char *hostname,
                           const char *password, FILE *file) {
    TokenError error = TokenError_Unknown;
    PKCS12 *p12 = NULL;
    
    // Add PKCS7 safes with the keys
    STACK_OF(PKCS7) *authsafes = NULL;
    uint32_t localKeyId = 0;
    size_t error_count = 0;
    while (reqs) {
        STACK_OF(PKCS12_SAFEBAG) *bags = NULL;
        X509 *cert = NULL;
        ASN1_OBJECT *objOwningHost = NULL;
        uint32_t keyid = htonl(localKeyId++);
        bool success = false;
        
        // Add private key
        PKCS12_SAFEBAG *bag = PKCS12_add_key(&bags, reqs->privkey,
            opensslKeyUsages[reqs->pkcs10->keyUsage], ENC_ITER, ENC_NID, (char*)password);
        if (!bag) goto loop_end;
        
        // Add name and localKeyId to the key bag
        // TODO extract name from subject DN
        char *name = "names are not implemented yet";
        if (!X509at_add1_attr_by_NID(&bag->attrib, NID_friendlyName, MBSTRING_UTF8,
                                     (unsigned char*)name, strlen(name)) ||
            !PKCS12_add_localkeyid(bag, (unsigned char*)&keyid, sizeof(keyid)))
            goto loop_end;
        
        // Add a certificate so we can find the key by the subject name
        cert = X509_REQ_to_X509(reqs->x509, 3650, reqs->privkey);
        if (!cert ||
            !X509_keyid_set1(cert, (unsigned char*)&keyid, sizeof(keyid)))
            goto loop_end;
        
        if (!X509_add_ext(cert, makeKeyUsageExt(reqs->pkcs10->keyUsage), -1))
            goto loop_end;
        
        if (!PKCS12_add_cert(&bags, cert))
            goto loop_end;
        
        // Add hostname (FriBID extension) so we can do same-origin checks
        // TODO maybe we should use document.domain instead of document.location.hostname?
        objOwningHost = OBJ_txt2obj(OID_OWNING_HOST, 1);
        if (!objOwningHost) goto loop_end;
        
        bag = sk_PKCS12_SAFEBAG_value(bags, sk_PKCS12_SAFEBAG_num(bags)-1);
        if (!X509at_add1_attr_by_OBJ(&bag->attrib, objOwningHost, MBSTRING_UTF8,
                                     (unsigned char*)hostname, strlen(hostname)))
            goto loop_end;
        
        
        // Add a new authsafe
        if (!PKCS12_add_safe(&authsafes, bags, -1, 0, NULL))
            goto loop_end;
        
        
        // Success!
        success = true;
        
      loop_end:
        if (!success) {
            error_count--;
            certutil_updateErrorString();
        }
        ASN1_OBJECT_free(objOwningHost);
        X509_free(cert);
        sk_PKCS12_SAFEBAG_pop_free(bags, PKCS12_SAFEBAG_free);
        reqs = reqs->next;
    }
    
    if (error_count != 0)
        goto end;
    
    // Create the PKCS12 wrapper
    p12 = PKCS12_add_safes(authsafes, 0);
    if (!p12) {
        certutil_updateErrorString();
        goto end;
    }
    PKCS12_set_mac(p12, (char*)password, -1, NULL, 0, MAC_ITER, NULL);
    
    // Save file
    if (!i2d_PKCS12_fp(file, p12)) {
        certutil_updateErrorString();
        error = TokenError_CantWriteToFile;
        goto end;
    }
    
    // Done!
    error = TokenError_Success;
    
  end:
    sk_PKCS7_pop_free(authsafes, PKCS7_free);
    PKCS12_free(p12);
    return error;
}

TokenError _backend_createRequest(const RegutilInfo *info,
                                  const char *hostname,
                                  const char *password,
                                  char **request, size_t *reqlen) {
    // OpenSSL seeds the PRNG automatically, see the manual page for RAND_add.
    if (!RAND_status()) {
        fprintf(stderr, BINNAME ": no random state!\n");
        return TokenError_NoRandomState;
    }
    
    // Abort if there are no requests
    *request = NULL;
    if (!info->pkcs10) return TokenError_Unknown;
    
    // Create certificate requests
    bool ok = true;
    CertReq *reqs = NULL;
    STACK *x509reqs = sk_new_null();
    if (!x509reqs) return TokenError_Unknown;
    for (const RegutilPKCS10 *pkcs10 = info->pkcs10; pkcs10 != NULL;
         pkcs10 = pkcs10->next) {
        
        RSA *rsa = NULL;
        EVP_PKEY *privkey = NULL;
        X509_NAME *subject = NULL;
        X509_REQ *x509req = NULL;
        STACK_OF(X509_EXTENSION) *exts = NULL;
        
        // Check the parameters.
        // Maximum key size in OpenSSL:
        // http://www.mail-archive.com/openssl-users@openssl.org/msg58229.html
        if (!pkcs10->subjectDN || pkcs10->keySize < 1024 ||
            pkcs10->keySize > 16384)
            goto req_error;
        
        // Generate key pair
        // FIXME deprecated function
        // TODO use OPENSSL_NO_DEPRECATED
        rsa = RSA_generate_key(pkcs10->keySize, RSA_F4, NULL, NULL);
        if (!rsa) goto req_error;
        privkey = EVP_PKEY_new();
        if (!privkey) goto req_error;
        EVP_PKEY_assign_RSA(privkey, rsa);
        
        // Subject name
        subject = certutil_parse_dn(pkcs10->subjectDN, pkcs10->includeFullDN);
        if (!subject) goto req_error;
        
        // Create request
        x509req = X509_REQ_new();
        if (!x509req ||
            !X509_REQ_set_version(x509req, 0) ||
            !X509_REQ_set_subject_name(x509req, subject) ||
            !X509_REQ_set_pubkey(x509req, privkey)) { // yes this is correct(!)
            
            certutil_updateErrorString();
            goto req_error;
        }
        
        // Set attributes
        exts = sk_X509_EXTENSION_new_null();
        if (!exts) goto req_error;
        
        X509_EXTENSION *ext = makeKeyUsageExt(pkcs10->keyUsage);
        if (!ext || !sk_X509_EXTENSION_push(exts, ext))
            goto req_error;
        
        if (!X509_REQ_add_extensions(x509req, exts)) {
            certutil_updateErrorString();
            goto req_error;
        }
        exts = NULL;
        
        // Add signature
        if (!X509_REQ_sign(x509req, privkey, EVP_sha1())) {
            certutil_updateErrorString();
            goto req_error;
        }
        
        // Store in list
        CertReq *req = malloc(sizeof(CertReq));
        if (!req) goto req_error;
        req->pkcs10 = pkcs10;
        req->privkey = privkey;
        req->rsa = rsa;
        req->x509 = x509req;
        req->next = reqs;
        reqs = req;
        
        sk_push(x509reqs, (char*)x509req);
        
        continue;
        
      req_error:
        // Clean up and set error flag
        if (privkey) EVP_PKEY_free(privkey);
        else if (rsa) RSA_free(rsa);
        
        X509_NAME_free(subject);
        sk_X509_EXTENSION_pop_free(exts, X509_EXTENSION_free);
        X509_REQ_free(x509req);
        
        ok = false;
    }
    
    TokenError error = TokenError_Unknown;
    
    if (ok) {
        // Determine filename from certificate name
        char *filename = certutil_makeFilename(X509_REQ_get_subject_name(reqs->x509));
        
        // Build the certificate request
        request_wrap(x509reqs, request, reqlen);
        
        if (*request && filename) {
            // Create the key file in ~/cbt/name.p12
            FILE *keyfile = platform_openLocked(filename, Platform_OpenCreate);
            if (!keyfile) {
                error = TokenError_CantCreateFile;
            } else {
                error = saveKeys(reqs, hostname, password, keyfile);
                if (!platform_closeLocked(keyfile) && !error)
                    error = TokenError_CantCreateFile;
            }
            
        }
        
        if (filename) free(filename);
        if (error && *request) free(*request);
    }
    
    // Free reqs
    while (reqs) {
        RSA_free(reqs->rsa); // This free's privkey too
        X509_REQ_free(reqs->x509);
        
        CertReq *next = reqs->next;
        free(reqs);
        reqs = next;
    }
    sk_free(x509reqs);
    
    return error;
}

static TokenError storeCertificates(STACK_OF(X509) *certs,
                                    const char *hostname,
                                    const char *filename) {
    TokenError error = TokenError_Unknown;
    PKCS12 *p12 = NULL;
    STACK_OF(PKCS7) *authsafes = NULL;
    FILE *newFile = NULL;
    char *tempname = NULL;
    bool modified = false;
    
    // Attempt to create new file first
    // (to avoid race conditions)
    tempname = rasprintf("%s.tmp", filename);
    if (!tempname) goto end;
    newFile = platform_openLocked(tempname, Platform_OpenCreate);
    if (!newFile) goto end;
    
    // Load file
    FILE *orig = platform_openLocked(filename, Platform_OpenRead);
    if (!orig) goto end;
    d2i_PKCS12_fp(orig, &p12);
    platform_closeLocked(orig);
    if (!p12) {
        certutil_updateErrorString();
        goto end;
    }
    
    // For each PKCS7 safe
    authsafes = PKCS12_unpack_authsafes(p12);
    if (!authsafes) goto end;
    int nump = sk_PKCS7_num(authsafes);
    for (int p = 0; p < nump; p++) {
        PKCS7 *p7 = sk_PKCS7_value(authsafes, p);
        if (!p7) continue;
        
        STACK_OF(PKCS12_SAFEBAG) *safebags = PKCS12_unpack_p7data(p7);
        if (!safebags) continue;
        
        // For each safebag
        bool match = false;
        int numsb = sk_PKCS12_SAFEBAG_num(safebags);
        for (int i = 0; i < numsb; i++) {
            PKCS12_SAFEBAG *bag = sk_PKCS12_SAFEBAG_value(safebags, i);
            if (!bag || M_PKCS12_bag_type(bag) != NID_certBag) continue;
            
            // Perform same-origin check
            ASN1_OBJECT *objOwningHost = OBJ_txt2obj(OID_OWNING_HOST, 1);
            if (!objOwningHost) continue;
            
            char *origin = certutil_getBagAttr(bag, objOwningHost);
            bool equal = (origin && strcmp(origin, hostname) == 0);
            free(origin);
            ASN1_OBJECT_free(objOwningHost);
            if (!equal) continue;
            
            // Extract cert from bag
            X509 *cert = PKCS12_certbag2x509(bag);
            if (!cert) {
                certutil_updateErrorString();
                continue;
            }
            
            // Get subject name and key usage
            X509_NAME *name = X509_get_subject_name(cert);
            
            ASN1_BIT_STRING *usage = X509_get_ext_d2i(cert, NID_key_usage,
                                                      NULL, NULL);
            if (name && usage && usage->length > 0) {
                KeyUsage keyUsage =
                    ((usage->data[0] & X509v3_KU_NON_REPUDIATION) == X509v3_KU_NON_REPUDIATION ?
                        KeyUsage_Signing : KeyUsage_Authentication);
                
                // Check if it matches
                X509 *issuedCert = certutil_findCert(certs, name,
                                                     keyUsage, true);
                if (issuedCert) {
                    // Remove temporary cert
                    (void)sk_PKCS12_SAFEBAG_delete(safebags, i);
                    int lkidLength;
                    unsigned char *lkid = X509_keyid_get0(cert, &lkidLength);
                    
                    // Link this cert to the key
                    if (lkid) {
                        X509_keyid_set1(issuedCert, lkid, lkidLength);
                    }
                    
                    match = true;
                }
            }
            
            X509_free(cert);
            ASN1_BIT_STRING_free(usage);
        }
        
        if (match) {
            // Add certs
            int num_certs = sk_X509_num(certs);
            for (int ci = 0; ci < num_certs; ci++) {
                X509 *cert = sk_X509_value(certs, ci);
                PKCS12_add_cert(&safebags, cert);
            }
            
            
            // Update PKCS12
            (void)sk_PKCS7_delete(authsafes, p);
            PKCS12_add_safe(&authsafes, safebags, -1, 0, NULL);
            
            p12 = PKCS12_add_safes(authsafes, 0);
            
            // TODO We don't add a MAC here. Does the official client require
            //      a MAC in PKCS#12 certs? Obviously we need the password
            //      to add a MAC, which we no longer have at this point.
            //
            //      The process that created the request (and asked for a
            //      password) could stay alive (it knows the password) a
            //      few minutes so StoreCertificates could add a MAC or
            //      even add certificates through it.
            //PKCS12_set_mac(p12, "123456qwerty", -1, NULL, 0, MAC_ITER, NULL);
            
            modified = true;
            break;
        }
        
        sk_PKCS12_SAFEBAG_pop_free(safebags, PKCS12_SAFEBAG_free);
    }
    
    sk_PKCS7_pop_free(authsafes, PKCS7_free);
    
    if (!modified || !p12) goto end;
    
    // Save
    if (!i2d_PKCS12_fp(newFile, p12)) {
        certutil_updateErrorString();
        goto end;
    }
    
    if (platform_closeLocked(newFile)) {
       newFile = NULL;
       
       // Replace old file with the new one
       if (rename(tempname, filename) == 0)
           error = TokenError_Success;
    }
    
  end:
    if (newFile) platform_deleteLocked(newFile, tempname);
    free(tempname);
    PKCS12_free(p12);
    
    // Write error (if any) to stderr
    if (!p12) {
        fprintf(stderr, BINNAME ": failed to open or parse file to store "
                "certs in %s\n", filename);
    } else if (!modified) {
        fprintf(stderr, BINNAME ": no certs matched the key file %s\n",
                filename);
    } else if (error) {
        fprintf(stderr, BINNAME ": failed to store certificates in %s\n",
                filename);
    }
    
    return error;
}

TokenError _backend_storeCertificates(const char *p7data, size_t length,
                                      const char *hostname) {
    
    PKCS7 *p7 = certutil_parseP7SignedData(p7data, length);
    if (!p7) return TokenError_Unknown;
    
    // Find the own cert
    TokenError error = TokenError_Unknown;
    STACK_OF(X509) *certs = p7->d.sign->cert;
    X509 *self = NULL;
    int numc = sk_X509_num(certs);
    for (int i = 0; i < numc; i++) {
        X509 *cert = sk_X509_value(certs, i);
        // TODO maybe we should look at the certificate chain instead?
        ASN1_BIT_STRING *usage = X509_get_ext_d2i(cert, NID_key_usage,
                                                  NULL, NULL);
        if (usage && usage->length > 0 &&
            (usage->data[0] & (X509v3_KU_DIGITAL_SIGNATURE | X509v3_KU_NON_REPUDIATION)) != 0) {
            // Issuer certs generally can't be used for signatures,
            // so assume this is our own cert
            self = cert;
            break;
        }
    }
    
    if (self) {
        // Get file name
        char *filename = certutil_makeFilename(X509_get_subject_name(self));
        
        // Add the certs to this file
        if (filename) {
            error = storeCertificates(certs, hostname, filename);
            free(filename);
        }
    }
    
    PKCS7_free(p7);
    return error;
}

Backend *pkcs12_getBackend(void) {
    Backend *backend = calloc(1, sizeof(Backend));
    backend->init = _backend_init;
    backend->free = _backend_free;
    backend->freeToken = _backend_freeToken;
    backend->addFile = _backend_addFile;
    backend->createRequest = _backend_createRequest;
    backend->storeCertificates = _backend_storeCertificates;
    backend->getBase64Chain = _backend_getBase64Chain;
    backend->sign = _backend_sign;
    return backend;
}