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1/* X.509 certificate parser
2 *
3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#define pr_fmt(fmt) "X.509: "fmt
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/slab.h>
16#include <linux/err.h>
17#include <linux/oid_registry.h>
18#include <crypto/public_key.h>
19#include "x509_parser.h"
20#include "x509-asn1.h"
21#include "x509_akid-asn1.h"
22
23struct x509_parse_context {
24 struct x509_certificate *cert; /* Certificate being constructed */
25 unsigned long data; /* Start of data */
26 const void *cert_start; /* Start of cert content */
27 const void *key; /* Key data */
28 size_t key_size; /* Size of key data */
29 enum OID last_oid; /* Last OID encountered */
30 enum OID algo_oid; /* Algorithm OID */
31 unsigned char nr_mpi; /* Number of MPIs stored */
32 u8 o_size; /* Size of organizationName (O) */
33 u8 cn_size; /* Size of commonName (CN) */
34 u8 email_size; /* Size of emailAddress */
35 u16 o_offset; /* Offset of organizationName (O) */
36 u16 cn_offset; /* Offset of commonName (CN) */
37 u16 email_offset; /* Offset of emailAddress */
38 unsigned raw_akid_size;
39 const void *raw_akid; /* Raw authorityKeyId in ASN.1 */
40 const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */
41 unsigned akid_raw_issuer_size;
42};
43
44/*
45 * Free an X.509 certificate
46 */
47void x509_free_certificate(struct x509_certificate *cert)
48{
49 if (cert) {
50 public_key_destroy(cert->pub);
51 kfree(cert->issuer);
52 kfree(cert->subject);
53 kfree(cert->id);
54 kfree(cert->skid);
55 kfree(cert->akid_id);
56 kfree(cert->akid_skid);
57 kfree(cert->sig.digest);
58 kfree(cert->sig.s);
59 kfree(cert);
60 }
61}
62EXPORT_SYMBOL_GPL(x509_free_certificate);
63
64/*
65 * Parse an X.509 certificate
66 */
67struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
68{
69 struct x509_certificate *cert;
70 struct x509_parse_context *ctx;
71 struct asymmetric_key_id *kid;
72 long ret;
73
74 ret = -ENOMEM;
75 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
76 if (!cert)
77 goto error_no_cert;
78 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
79 if (!cert->pub)
80 goto error_no_ctx;
81 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
82 if (!ctx)
83 goto error_no_ctx;
84
85 ctx->cert = cert;
86 ctx->data = (unsigned long)data;
87
88 /* Attempt to decode the certificate */
89 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
90 if (ret < 0)
91 goto error_decode;
92
93 /* Decode the AuthorityKeyIdentifier */
94 if (ctx->raw_akid) {
95 pr_devel("AKID: %u %*phN\n",
96 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
97 ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
98 ctx->raw_akid, ctx->raw_akid_size);
99 if (ret < 0) {
100 pr_warn("Couldn't decode AuthKeyIdentifier\n");
101 goto error_decode;
102 }
103 }
104
105 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
106 if (!cert->pub->key)
107 goto error_decode;
108
109 cert->pub->keylen = ctx->key_size;
110
111 /* Generate cert issuer + serial number key ID */
112 kid = asymmetric_key_generate_id(cert->raw_serial,
113 cert->raw_serial_size,
114 cert->raw_issuer,
115 cert->raw_issuer_size);
116 if (IS_ERR(kid)) {
117 ret = PTR_ERR(kid);
118 goto error_decode;
119 }
120 cert->id = kid;
121
122 kfree(ctx);
123 return cert;
124
125error_decode:
126 kfree(cert->pub->key);
127 kfree(ctx);
128error_no_ctx:
129 x509_free_certificate(cert);
130error_no_cert:
131 return ERR_PTR(ret);
132}
133EXPORT_SYMBOL_GPL(x509_cert_parse);
134
135/*
136 * Note an OID when we find one for later processing when we know how
137 * to interpret it.
138 */
139int x509_note_OID(void *context, size_t hdrlen,
140 unsigned char tag,
141 const void *value, size_t vlen)
142{
143 struct x509_parse_context *ctx = context;
144
145 ctx->last_oid = look_up_OID(value, vlen);
146 if (ctx->last_oid == OID__NR) {
147 char buffer[50];
148 sprint_oid(value, vlen, buffer, sizeof(buffer));
149 pr_debug("Unknown OID: [%lu] %s\n",
150 (unsigned long)value - ctx->data, buffer);
151 }
152 return 0;
153}
154
155/*
156 * Save the position of the TBS data so that we can check the signature over it
157 * later.
158 */
159int x509_note_tbs_certificate(void *context, size_t hdrlen,
160 unsigned char tag,
161 const void *value, size_t vlen)
162{
163 struct x509_parse_context *ctx = context;
164
165 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
166 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
167
168 ctx->cert->tbs = value - hdrlen;
169 ctx->cert->tbs_size = vlen + hdrlen;
170 return 0;
171}
172
173/*
174 * Record the public key algorithm
175 */
176int x509_note_pkey_algo(void *context, size_t hdrlen,
177 unsigned char tag,
178 const void *value, size_t vlen)
179{
180 struct x509_parse_context *ctx = context;
181
182 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
183
184 switch (ctx->last_oid) {
185 case OID_md2WithRSAEncryption:
186 case OID_md3WithRSAEncryption:
187 default:
188 return -ENOPKG; /* Unsupported combination */
189
190 case OID_md4WithRSAEncryption:
191 ctx->cert->sig.hash_algo = "md4";
192 ctx->cert->sig.pkey_algo = "rsa";
193 break;
194
195 case OID_sha1WithRSAEncryption:
196 ctx->cert->sig.hash_algo = "sha1";
197 ctx->cert->sig.pkey_algo = "rsa";
198 break;
199
200 case OID_sha256WithRSAEncryption:
201 ctx->cert->sig.hash_algo = "sha256";
202 ctx->cert->sig.pkey_algo = "rsa";
203 break;
204
205 case OID_sha384WithRSAEncryption:
206 ctx->cert->sig.hash_algo = "sha384";
207 ctx->cert->sig.pkey_algo = "rsa";
208 break;
209
210 case OID_sha512WithRSAEncryption:
211 ctx->cert->sig.hash_algo = "sha512";
212 ctx->cert->sig.pkey_algo = "rsa";
213 break;
214
215 case OID_sha224WithRSAEncryption:
216 ctx->cert->sig.hash_algo = "sha224";
217 ctx->cert->sig.pkey_algo = "rsa";
218 break;
219 }
220
221 ctx->algo_oid = ctx->last_oid;
222 return 0;
223}
224
225/*
226 * Note the whereabouts and type of the signature.
227 */
228int x509_note_signature(void *context, size_t hdrlen,
229 unsigned char tag,
230 const void *value, size_t vlen)
231{
232 struct x509_parse_context *ctx = context;
233
234 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
235
236 if (ctx->last_oid != ctx->algo_oid) {
237 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
238 ctx->algo_oid, ctx->last_oid);
239 return -EINVAL;
240 }
241
242 ctx->cert->raw_sig = value;
243 ctx->cert->raw_sig_size = vlen;
244 return 0;
245}
246
247/*
248 * Note the certificate serial number
249 */
250int x509_note_serial(void *context, size_t hdrlen,
251 unsigned char tag,
252 const void *value, size_t vlen)
253{
254 struct x509_parse_context *ctx = context;
255 ctx->cert->raw_serial = value;
256 ctx->cert->raw_serial_size = vlen;
257 return 0;
258}
259
260/*
261 * Note some of the name segments from which we'll fabricate a name.
262 */
263int x509_extract_name_segment(void *context, size_t hdrlen,
264 unsigned char tag,
265 const void *value, size_t vlen)
266{
267 struct x509_parse_context *ctx = context;
268
269 switch (ctx->last_oid) {
270 case OID_commonName:
271 ctx->cn_size = vlen;
272 ctx->cn_offset = (unsigned long)value - ctx->data;
273 break;
274 case OID_organizationName:
275 ctx->o_size = vlen;
276 ctx->o_offset = (unsigned long)value - ctx->data;
277 break;
278 case OID_email_address:
279 ctx->email_size = vlen;
280 ctx->email_offset = (unsigned long)value - ctx->data;
281 break;
282 default:
283 break;
284 }
285
286 return 0;
287}
288
289/*
290 * Fabricate and save the issuer and subject names
291 */
292static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
293 unsigned char tag,
294 char **_name, size_t vlen)
295{
296 const void *name, *data = (const void *)ctx->data;
297 size_t namesize;
298 char *buffer;
299
300 if (*_name)
301 return -EINVAL;
302
303 /* Empty name string if no material */
304 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
305 buffer = kmalloc(1, GFP_KERNEL);
306 if (!buffer)
307 return -ENOMEM;
308 buffer[0] = 0;
309 goto done;
310 }
311
312 if (ctx->cn_size && ctx->o_size) {
313 /* Consider combining O and CN, but use only the CN if it is
314 * prefixed by the O, or a significant portion thereof.
315 */
316 namesize = ctx->cn_size;
317 name = data + ctx->cn_offset;
318 if (ctx->cn_size >= ctx->o_size &&
319 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
320 ctx->o_size) == 0)
321 goto single_component;
322 if (ctx->cn_size >= 7 &&
323 ctx->o_size >= 7 &&
324 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
325 goto single_component;
326
327 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
328 GFP_KERNEL);
329 if (!buffer)
330 return -ENOMEM;
331
332 memcpy(buffer,
333 data + ctx->o_offset, ctx->o_size);
334 buffer[ctx->o_size + 0] = ':';
335 buffer[ctx->o_size + 1] = ' ';
336 memcpy(buffer + ctx->o_size + 2,
337 data + ctx->cn_offset, ctx->cn_size);
338 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
339 goto done;
340
341 } else if (ctx->cn_size) {
342 namesize = ctx->cn_size;
343 name = data + ctx->cn_offset;
344 } else if (ctx->o_size) {
345 namesize = ctx->o_size;
346 name = data + ctx->o_offset;
347 } else {
348 namesize = ctx->email_size;
349 name = data + ctx->email_offset;
350 }
351
352single_component:
353 buffer = kmalloc(namesize + 1, GFP_KERNEL);
354 if (!buffer)
355 return -ENOMEM;
356 memcpy(buffer, name, namesize);
357 buffer[namesize] = 0;
358
359done:
360 *_name = buffer;
361 ctx->cn_size = 0;
362 ctx->o_size = 0;
363 ctx->email_size = 0;
364 return 0;
365}
366
367int x509_note_issuer(void *context, size_t hdrlen,
368 unsigned char tag,
369 const void *value, size_t vlen)
370{
371 struct x509_parse_context *ctx = context;
372 ctx->cert->raw_issuer = value;
373 ctx->cert->raw_issuer_size = vlen;
374 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
375}
376
377int x509_note_subject(void *context, size_t hdrlen,
378 unsigned char tag,
379 const void *value, size_t vlen)
380{
381 struct x509_parse_context *ctx = context;
382 ctx->cert->raw_subject = value;
383 ctx->cert->raw_subject_size = vlen;
384 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
385}
386
387/*
388 * Extract the data for the public key algorithm
389 */
390int x509_extract_key_data(void *context, size_t hdrlen,
391 unsigned char tag,
392 const void *value, size_t vlen)
393{
394 struct x509_parse_context *ctx = context;
395
396 if (ctx->last_oid != OID_rsaEncryption)
397 return -ENOPKG;
398
399 ctx->cert->pub->pkey_algo = "rsa";
400
401 /* Discard the BIT STRING metadata */
402 ctx->key = value + 1;
403 ctx->key_size = vlen - 1;
404 return 0;
405}
406
407/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
408#define SEQ_TAG_KEYID (ASN1_CONT << 6)
409
410/*
411 * Process certificate extensions that are used to qualify the certificate.
412 */
413int x509_process_extension(void *context, size_t hdrlen,
414 unsigned char tag,
415 const void *value, size_t vlen)
416{
417 struct x509_parse_context *ctx = context;
418 struct asymmetric_key_id *kid;
419 const unsigned char *v = value;
420
421 pr_debug("Extension: %u\n", ctx->last_oid);
422
423 if (ctx->last_oid == OID_subjectKeyIdentifier) {
424 /* Get hold of the key fingerprint */
425 if (ctx->cert->skid || vlen < 3)
426 return -EBADMSG;
427 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
428 return -EBADMSG;
429 v += 2;
430 vlen -= 2;
431
432 ctx->cert->raw_skid_size = vlen;
433 ctx->cert->raw_skid = v;
434 kid = asymmetric_key_generate_id(v, vlen, "", 0);
435 if (IS_ERR(kid))
436 return PTR_ERR(kid);
437 ctx->cert->skid = kid;
438 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
439 return 0;
440 }
441
442 if (ctx->last_oid == OID_authorityKeyIdentifier) {
443 /* Get hold of the CA key fingerprint */
444 ctx->raw_akid = v;
445 ctx->raw_akid_size = vlen;
446 return 0;
447 }
448
449 return 0;
450}
451
452/**
453 * x509_decode_time - Decode an X.509 time ASN.1 object
454 * @_t: The time to fill in
455 * @hdrlen: The length of the object header
456 * @tag: The object tag
457 * @value: The object value
458 * @vlen: The size of the object value
459 *
460 * Decode an ASN.1 universal time or generalised time field into a struct the
461 * kernel can handle and check it for validity. The time is decoded thus:
462 *
463 * [RFC5280 ยง4.1.2.5]
464 * CAs conforming to this profile MUST always encode certificate validity
465 * dates through the year 2049 as UTCTime; certificate validity dates in
466 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
467 * applications MUST be able to process validity dates that are encoded in
468 * either UTCTime or GeneralizedTime.
469 */
470int x509_decode_time(time64_t *_t, size_t hdrlen,
471 unsigned char tag,
472 const unsigned char *value, size_t vlen)
473{
474 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
475 31, 31, 30, 31, 30, 31 };
476 const unsigned char *p = value;
477 unsigned year, mon, day, hour, min, sec, mon_len;
478
479#define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
480#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
481
482 if (tag == ASN1_UNITIM) {
483 /* UTCTime: YYMMDDHHMMSSZ */
484 if (vlen != 13)
485 goto unsupported_time;
486 year = DD2bin(p);
487 if (year >= 50)
488 year += 1900;
489 else
490 year += 2000;
491 } else if (tag == ASN1_GENTIM) {
492 /* GenTime: YYYYMMDDHHMMSSZ */
493 if (vlen != 15)
494 goto unsupported_time;
495 year = DD2bin(p) * 100 + DD2bin(p);
496 if (year >= 1950 && year <= 2049)
497 goto invalid_time;
498 } else {
499 goto unsupported_time;
500 }
501
502 mon = DD2bin(p);
503 day = DD2bin(p);
504 hour = DD2bin(p);
505 min = DD2bin(p);
506 sec = DD2bin(p);
507
508 if (*p != 'Z')
509 goto unsupported_time;
510
511 if (year < 1970 ||
512 mon < 1 || mon > 12)
513 goto invalid_time;
514
515 mon_len = month_lengths[mon - 1];
516 if (mon == 2) {
517 if (year % 4 == 0) {
518 mon_len = 29;
519 if (year % 100 == 0) {
520 mon_len = 28;
521 if (year % 400 == 0)
522 mon_len = 29;
523 }
524 }
525 }
526
527 if (day < 1 || day > mon_len ||
528 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
529 min > 59 ||
530 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
531 goto invalid_time;
532
533 *_t = mktime64(year, mon, day, hour, min, sec);
534 return 0;
535
536unsupported_time:
537 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
538 tag, (int)vlen, value);
539 return -EBADMSG;
540invalid_time:
541 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
542 tag, (int)vlen, value);
543 return -EBADMSG;
544}
545EXPORT_SYMBOL_GPL(x509_decode_time);
546
547int x509_note_not_before(void *context, size_t hdrlen,
548 unsigned char tag,
549 const void *value, size_t vlen)
550{
551 struct x509_parse_context *ctx = context;
552 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
553}
554
555int x509_note_not_after(void *context, size_t hdrlen,
556 unsigned char tag,
557 const void *value, size_t vlen)
558{
559 struct x509_parse_context *ctx = context;
560 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
561}
562
563/*
564 * Note a key identifier-based AuthorityKeyIdentifier
565 */
566int x509_akid_note_kid(void *context, size_t hdrlen,
567 unsigned char tag,
568 const void *value, size_t vlen)
569{
570 struct x509_parse_context *ctx = context;
571 struct asymmetric_key_id *kid;
572
573 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
574
575 if (ctx->cert->akid_skid)
576 return 0;
577
578 kid = asymmetric_key_generate_id(value, vlen, "", 0);
579 if (IS_ERR(kid))
580 return PTR_ERR(kid);
581 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
582 ctx->cert->akid_skid = kid;
583 return 0;
584}
585
586/*
587 * Note a directoryName in an AuthorityKeyIdentifier
588 */
589int x509_akid_note_name(void *context, size_t hdrlen,
590 unsigned char tag,
591 const void *value, size_t vlen)
592{
593 struct x509_parse_context *ctx = context;
594
595 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
596
597 ctx->akid_raw_issuer = value;
598 ctx->akid_raw_issuer_size = vlen;
599 return 0;
600}
601
602/*
603 * Note a serial number in an AuthorityKeyIdentifier
604 */
605int x509_akid_note_serial(void *context, size_t hdrlen,
606 unsigned char tag,
607 const void *value, size_t vlen)
608{
609 struct x509_parse_context *ctx = context;
610 struct asymmetric_key_id *kid;
611
612 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
613
614 if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
615 return 0;
616
617 kid = asymmetric_key_generate_id(value,
618 vlen,
619 ctx->akid_raw_issuer,
620 ctx->akid_raw_issuer_size);
621 if (IS_ERR(kid))
622 return PTR_ERR(kid);
623
624 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
625 ctx->cert->akid_id = kid;
626 return 0;
627}