blob: a668d90302d38c541fb5a78aa5442019cc739b21 [file] [log] [blame]
David Howellsc26fd692012-09-24 17:11:48 +01001/* 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>
David Howellsace01072014-07-01 16:40:19 +010014#include <linux/export.h>
David Howellsc26fd692012-09-24 17:11:48 +010015#include <linux/slab.h>
16#include <linux/err.h>
17#include <linux/oid_registry.h>
18#include "public_key.h"
19#include "x509_parser.h"
20#include "x509-asn1.h"
21#include "x509_rsakey-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};
39
40/*
41 * Free an X.509 certificate
42 */
43void x509_free_certificate(struct x509_certificate *cert)
44{
45 if (cert) {
46 public_key_destroy(cert->pub);
47 kfree(cert->issuer);
48 kfree(cert->subject);
David Howells46963b72014-09-16 17:36:13 +010049 kfree(cert->id);
50 kfree(cert->skid);
David Howellsc26fd692012-09-24 17:11:48 +010051 kfree(cert->authority);
David Howellsb426beb2013-08-30 16:18:02 +010052 kfree(cert->sig.digest);
53 mpi_free(cert->sig.rsa.s);
David Howellsc26fd692012-09-24 17:11:48 +010054 kfree(cert);
55 }
56}
David Howellsace01072014-07-01 16:40:19 +010057EXPORT_SYMBOL_GPL(x509_free_certificate);
David Howellsc26fd692012-09-24 17:11:48 +010058
59/*
60 * Parse an X.509 certificate
61 */
62struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
63{
64 struct x509_certificate *cert;
65 struct x509_parse_context *ctx;
David Howells46963b72014-09-16 17:36:13 +010066 struct asymmetric_key_id *kid;
David Howellsc26fd692012-09-24 17:11:48 +010067 long ret;
68
69 ret = -ENOMEM;
70 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
71 if (!cert)
72 goto error_no_cert;
73 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
74 if (!cert->pub)
75 goto error_no_ctx;
76 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
77 if (!ctx)
78 goto error_no_ctx;
79
80 ctx->cert = cert;
81 ctx->data = (unsigned long)data;
82
83 /* Attempt to decode the certificate */
84 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
85 if (ret < 0)
86 goto error_decode;
87
88 /* Decode the public key */
89 ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
90 ctx->key, ctx->key_size);
91 if (ret < 0)
92 goto error_decode;
93
David Howells46963b72014-09-16 17:36:13 +010094 /* Generate cert issuer + serial number key ID */
95 kid = asymmetric_key_generate_id(cert->raw_serial,
96 cert->raw_serial_size,
97 cert->raw_issuer,
98 cert->raw_issuer_size);
99 if (IS_ERR(kid)) {
100 ret = PTR_ERR(kid);
101 goto error_decode;
102 }
103 cert->id = kid;
104
David Howellsc26fd692012-09-24 17:11:48 +0100105 kfree(ctx);
106 return cert;
107
108error_decode:
109 kfree(ctx);
110error_no_ctx:
111 x509_free_certificate(cert);
112error_no_cert:
113 return ERR_PTR(ret);
114}
David Howellsace01072014-07-01 16:40:19 +0100115EXPORT_SYMBOL_GPL(x509_cert_parse);
David Howellsc26fd692012-09-24 17:11:48 +0100116
117/*
118 * Note an OID when we find one for later processing when we know how
119 * to interpret it.
120 */
121int x509_note_OID(void *context, size_t hdrlen,
122 unsigned char tag,
123 const void *value, size_t vlen)
124{
125 struct x509_parse_context *ctx = context;
126
127 ctx->last_oid = look_up_OID(value, vlen);
128 if (ctx->last_oid == OID__NR) {
129 char buffer[50];
130 sprint_oid(value, vlen, buffer, sizeof(buffer));
Randy Dunlapcf754462012-10-03 16:04:46 -0700131 pr_debug("Unknown OID: [%lu] %s\n",
David Howellsc26fd692012-09-24 17:11:48 +0100132 (unsigned long)value - ctx->data, buffer);
133 }
134 return 0;
135}
136
137/*
138 * Save the position of the TBS data so that we can check the signature over it
139 * later.
140 */
141int x509_note_tbs_certificate(void *context, size_t hdrlen,
142 unsigned char tag,
143 const void *value, size_t vlen)
144{
145 struct x509_parse_context *ctx = context;
146
147 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
148 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
149
150 ctx->cert->tbs = value - hdrlen;
151 ctx->cert->tbs_size = vlen + hdrlen;
152 return 0;
153}
154
155/*
156 * Record the public key algorithm
157 */
158int x509_note_pkey_algo(void *context, size_t hdrlen,
159 unsigned char tag,
160 const void *value, size_t vlen)
161{
162 struct x509_parse_context *ctx = context;
163
164 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
165
166 switch (ctx->last_oid) {
167 case OID_md2WithRSAEncryption:
168 case OID_md3WithRSAEncryption:
169 default:
170 return -ENOPKG; /* Unsupported combination */
171
172 case OID_md4WithRSAEncryption:
Dmitry Kasatkin3fe78ca2013-05-06 15:58:15 +0300173 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_MD5;
David Howellsb426beb2013-08-30 16:18:02 +0100174 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
David Howellsc26fd692012-09-24 17:11:48 +0100175 break;
176
177 case OID_sha1WithRSAEncryption:
Dmitry Kasatkin3fe78ca2013-05-06 15:58:15 +0300178 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1;
David Howellsb426beb2013-08-30 16:18:02 +0100179 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
David Howellsc26fd692012-09-24 17:11:48 +0100180 break;
181
182 case OID_sha256WithRSAEncryption:
Dmitry Kasatkin3fe78ca2013-05-06 15:58:15 +0300183 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256;
David Howellsb426beb2013-08-30 16:18:02 +0100184 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
David Howellsc26fd692012-09-24 17:11:48 +0100185 break;
186
187 case OID_sha384WithRSAEncryption:
Dmitry Kasatkin3fe78ca2013-05-06 15:58:15 +0300188 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384;
David Howellsb426beb2013-08-30 16:18:02 +0100189 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
David Howellsc26fd692012-09-24 17:11:48 +0100190 break;
191
192 case OID_sha512WithRSAEncryption:
Dmitry Kasatkin3fe78ca2013-05-06 15:58:15 +0300193 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512;
David Howellsb426beb2013-08-30 16:18:02 +0100194 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
David Howellsc26fd692012-09-24 17:11:48 +0100195 break;
196
197 case OID_sha224WithRSAEncryption:
Dmitry Kasatkin3fe78ca2013-05-06 15:58:15 +0300198 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224;
David Howellsb426beb2013-08-30 16:18:02 +0100199 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
David Howellsc26fd692012-09-24 17:11:48 +0100200 break;
201 }
202
203 ctx->algo_oid = ctx->last_oid;
204 return 0;
205}
206
207/*
208 * Note the whereabouts and type of the signature.
209 */
210int x509_note_signature(void *context, size_t hdrlen,
211 unsigned char tag,
212 const void *value, size_t vlen)
213{
214 struct x509_parse_context *ctx = context;
215
216 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
217
218 if (ctx->last_oid != ctx->algo_oid) {
219 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
220 ctx->algo_oid, ctx->last_oid);
221 return -EINVAL;
222 }
223
David Howellsb426beb2013-08-30 16:18:02 +0100224 ctx->cert->raw_sig = value;
225 ctx->cert->raw_sig_size = vlen;
David Howellsc26fd692012-09-24 17:11:48 +0100226 return 0;
227}
228
229/*
David Howells84aabd42014-07-01 16:40:19 +0100230 * Note the certificate serial number
231 */
232int x509_note_serial(void *context, size_t hdrlen,
233 unsigned char tag,
234 const void *value, size_t vlen)
235{
236 struct x509_parse_context *ctx = context;
237 ctx->cert->raw_serial = value;
238 ctx->cert->raw_serial_size = vlen;
239 return 0;
240}
241
242/*
David Howellsc26fd692012-09-24 17:11:48 +0100243 * Note some of the name segments from which we'll fabricate a name.
244 */
245int x509_extract_name_segment(void *context, size_t hdrlen,
246 unsigned char tag,
247 const void *value, size_t vlen)
248{
249 struct x509_parse_context *ctx = context;
250
251 switch (ctx->last_oid) {
252 case OID_commonName:
253 ctx->cn_size = vlen;
254 ctx->cn_offset = (unsigned long)value - ctx->data;
255 break;
256 case OID_organizationName:
257 ctx->o_size = vlen;
258 ctx->o_offset = (unsigned long)value - ctx->data;
259 break;
260 case OID_email_address:
261 ctx->email_size = vlen;
262 ctx->email_offset = (unsigned long)value - ctx->data;
263 break;
264 default:
265 break;
266 }
267
268 return 0;
269}
270
271/*
272 * Fabricate and save the issuer and subject names
273 */
274static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
275 unsigned char tag,
276 char **_name, size_t vlen)
277{
278 const void *name, *data = (const void *)ctx->data;
279 size_t namesize;
280 char *buffer;
281
282 if (*_name)
283 return -EINVAL;
284
285 /* Empty name string if no material */
286 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
287 buffer = kmalloc(1, GFP_KERNEL);
288 if (!buffer)
289 return -ENOMEM;
290 buffer[0] = 0;
291 goto done;
292 }
293
294 if (ctx->cn_size && ctx->o_size) {
295 /* Consider combining O and CN, but use only the CN if it is
296 * prefixed by the O, or a significant portion thereof.
297 */
298 namesize = ctx->cn_size;
299 name = data + ctx->cn_offset;
300 if (ctx->cn_size >= ctx->o_size &&
301 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
302 ctx->o_size) == 0)
303 goto single_component;
304 if (ctx->cn_size >= 7 &&
305 ctx->o_size >= 7 &&
306 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
307 goto single_component;
308
309 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
310 GFP_KERNEL);
311 if (!buffer)
312 return -ENOMEM;
313
314 memcpy(buffer,
315 data + ctx->o_offset, ctx->o_size);
316 buffer[ctx->o_size + 0] = ':';
317 buffer[ctx->o_size + 1] = ' ';
318 memcpy(buffer + ctx->o_size + 2,
319 data + ctx->cn_offset, ctx->cn_size);
320 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
321 goto done;
322
323 } else if (ctx->cn_size) {
324 namesize = ctx->cn_size;
325 name = data + ctx->cn_offset;
326 } else if (ctx->o_size) {
327 namesize = ctx->o_size;
328 name = data + ctx->o_offset;
329 } else {
330 namesize = ctx->email_size;
331 name = data + ctx->email_offset;
332 }
333
334single_component:
335 buffer = kmalloc(namesize + 1, GFP_KERNEL);
336 if (!buffer)
337 return -ENOMEM;
338 memcpy(buffer, name, namesize);
339 buffer[namesize] = 0;
340
341done:
342 *_name = buffer;
343 ctx->cn_size = 0;
344 ctx->o_size = 0;
345 ctx->email_size = 0;
346 return 0;
347}
348
349int x509_note_issuer(void *context, size_t hdrlen,
350 unsigned char tag,
351 const void *value, size_t vlen)
352{
353 struct x509_parse_context *ctx = context;
David Howells84aabd42014-07-01 16:40:19 +0100354 ctx->cert->raw_issuer = value;
355 ctx->cert->raw_issuer_size = vlen;
David Howellsc26fd692012-09-24 17:11:48 +0100356 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
357}
358
359int x509_note_subject(void *context, size_t hdrlen,
360 unsigned char tag,
361 const void *value, size_t vlen)
362{
363 struct x509_parse_context *ctx = context;
David Howells84aabd42014-07-01 16:40:19 +0100364 ctx->cert->raw_subject = value;
365 ctx->cert->raw_subject_size = vlen;
David Howellsc26fd692012-09-24 17:11:48 +0100366 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
367}
368
369/*
370 * Extract the data for the public key algorithm
371 */
372int x509_extract_key_data(void *context, size_t hdrlen,
373 unsigned char tag,
374 const void *value, size_t vlen)
375{
376 struct x509_parse_context *ctx = context;
377
378 if (ctx->last_oid != OID_rsaEncryption)
379 return -ENOPKG;
380
David Howells67f7d60b2013-08-30 16:15:24 +0100381 ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
382
383 /* Discard the BIT STRING metadata */
David Howellsc26fd692012-09-24 17:11:48 +0100384 ctx->key = value + 1;
385 ctx->key_size = vlen - 1;
386 return 0;
387}
388
389/*
390 * Extract a RSA public key value
391 */
392int rsa_extract_mpi(void *context, size_t hdrlen,
393 unsigned char tag,
394 const void *value, size_t vlen)
395{
396 struct x509_parse_context *ctx = context;
397 MPI mpi;
398
399 if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
400 pr_err("Too many public key MPIs in certificate\n");
401 return -EBADMSG;
402 }
403
404 mpi = mpi_read_raw_data(value, vlen);
405 if (!mpi)
406 return -ENOMEM;
407
408 ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
409 return 0;
410}
411
Chun-Yi Lee04b00bd2013-04-22 10:56:55 +0930412/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
413#define SEQ_TAG_KEYID (ASN1_CONT << 6)
414
David Howellsc26fd692012-09-24 17:11:48 +0100415/*
416 * Process certificate extensions that are used to qualify the certificate.
417 */
418int x509_process_extension(void *context, size_t hdrlen,
419 unsigned char tag,
420 const void *value, size_t vlen)
421{
422 struct x509_parse_context *ctx = context;
David Howells46963b72014-09-16 17:36:13 +0100423 struct asymmetric_key_id *kid;
David Howellsc26fd692012-09-24 17:11:48 +0100424 const unsigned char *v = value;
David Howellsc26fd692012-09-24 17:11:48 +0100425 int i;
426
427 pr_debug("Extension: %u\n", ctx->last_oid);
428
429 if (ctx->last_oid == OID_subjectKeyIdentifier) {
430 /* Get hold of the key fingerprint */
David Howells46963b72014-09-16 17:36:13 +0100431 if (ctx->cert->skid || vlen < 3)
David Howellsc26fd692012-09-24 17:11:48 +0100432 return -EBADMSG;
433 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
434 return -EBADMSG;
435 v += 2;
436 vlen -= 2;
437
David Howellsdd2f6c42014-10-03 16:17:02 +0100438 ctx->cert->raw_skid_size = vlen;
439 ctx->cert->raw_skid = v;
Dmitry Kasatkin8dd60982014-10-06 16:52:12 +0100440 kid = asymmetric_key_generate_id(ctx->cert->raw_subject,
441 ctx->cert->raw_subject_size,
442 v, vlen);
David Howells46963b72014-09-16 17:36:13 +0100443 if (IS_ERR(kid))
444 return PTR_ERR(kid);
445 ctx->cert->skid = kid;
446 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
David Howellsc26fd692012-09-24 17:11:48 +0100447 return 0;
448 }
449
450 if (ctx->last_oid == OID_authorityKeyIdentifier) {
451 /* Get hold of the CA key fingerprint */
David Howells46963b72014-09-16 17:36:13 +0100452 if (ctx->cert->authority || vlen < 5)
David Howellsc26fd692012-09-24 17:11:48 +0100453 return -EBADMSG;
David Howellsc26fd692012-09-24 17:11:48 +0100454
Chun-Yi Lee04b00bd2013-04-22 10:56:55 +0930455 /* Authority Key Identifier must be a Constructed SEQUENCE */
456 if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
457 return -EBADMSG;
458
459 /* Authority Key Identifier is not indefinite length */
460 if (unlikely(vlen == ASN1_INDEFINITE_LENGTH))
461 return -EBADMSG;
462
463 if (vlen < ASN1_INDEFINITE_LENGTH) {
464 /* Short Form length */
465 if (v[1] != vlen - 2 ||
466 v[2] != SEQ_TAG_KEYID ||
467 v[3] > vlen - 4)
468 return -EBADMSG;
469
David Howells46963b72014-09-16 17:36:13 +0100470 vlen = v[3];
Chun-Yi Lee04b00bd2013-04-22 10:56:55 +0930471 v += 4;
472 } else {
473 /* Long Form length */
474 size_t seq_len = 0;
475 size_t sub = v[1] - ASN1_INDEFINITE_LENGTH;
476
477 if (sub > 2)
478 return -EBADMSG;
479
480 /* calculate the length from subsequent octets */
481 v += 2;
482 for (i = 0; i < sub; i++) {
483 seq_len <<= 8;
484 seq_len |= v[i];
485 }
486
487 if (seq_len != vlen - 2 - sub ||
488 v[sub] != SEQ_TAG_KEYID ||
489 v[sub + 1] > vlen - 4 - sub)
490 return -EBADMSG;
491
David Howells46963b72014-09-16 17:36:13 +0100492 vlen = v[sub + 1];
Chun-Yi Lee04b00bd2013-04-22 10:56:55 +0930493 v += (sub + 2);
494 }
495
Dmitry Kasatkin8dd60982014-10-06 16:52:12 +0100496 kid = asymmetric_key_generate_id(ctx->cert->raw_issuer,
497 ctx->cert->raw_issuer_size,
498 v, vlen);
David Howells46963b72014-09-16 17:36:13 +0100499 if (IS_ERR(kid))
500 return PTR_ERR(kid);
501 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
502 ctx->cert->authority = kid;
David Howellsc26fd692012-09-24 17:11:48 +0100503 return 0;
504 }
505
506 return 0;
507}
508
509/*
510 * Record a certificate time.
511 */
David Howellsa5752d12012-10-02 14:36:16 +0100512static int x509_note_time(struct tm *tm, size_t hdrlen,
David Howellsc26fd692012-09-24 17:11:48 +0100513 unsigned char tag,
514 const unsigned char *value, size_t vlen)
515{
David Howellsc26fd692012-09-24 17:11:48 +0100516 const unsigned char *p = value;
517
518#define dec2bin(X) ((X) - '0')
519#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
520
521 if (tag == ASN1_UNITIM) {
522 /* UTCTime: YYMMDDHHMMSSZ */
523 if (vlen != 13)
524 goto unsupported_time;
David Howellsa5752d12012-10-02 14:36:16 +0100525 tm->tm_year = DD2bin(p);
526 if (tm->tm_year >= 50)
527 tm->tm_year += 1900;
David Howellsc26fd692012-09-24 17:11:48 +0100528 else
David Howellsa5752d12012-10-02 14:36:16 +0100529 tm->tm_year += 2000;
David Howellsc26fd692012-09-24 17:11:48 +0100530 } else if (tag == ASN1_GENTIM) {
531 /* GenTime: YYYYMMDDHHMMSSZ */
532 if (vlen != 15)
533 goto unsupported_time;
David Howellsa5752d12012-10-02 14:36:16 +0100534 tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
David Howellsc26fd692012-09-24 17:11:48 +0100535 } else {
536 goto unsupported_time;
537 }
538
David Howellsa5752d12012-10-02 14:36:16 +0100539 tm->tm_year -= 1900;
540 tm->tm_mon = DD2bin(p) - 1;
541 tm->tm_mday = DD2bin(p);
542 tm->tm_hour = DD2bin(p);
543 tm->tm_min = DD2bin(p);
544 tm->tm_sec = DD2bin(p);
David Howellsc26fd692012-09-24 17:11:48 +0100545
546 if (*p != 'Z')
547 goto unsupported_time;
548
David Howellsc26fd692012-09-24 17:11:48 +0100549 return 0;
550
551unsupported_time:
552 pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
553 tag, (int)vlen, (int)vlen, value);
554 return -EBADMSG;
555}
556
557int x509_note_not_before(void *context, size_t hdrlen,
558 unsigned char tag,
559 const void *value, size_t vlen)
560{
561 struct x509_parse_context *ctx = context;
562 return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
563}
564
565int x509_note_not_after(void *context, size_t hdrlen,
566 unsigned char tag,
567 const void *value, size_t vlen)
568{
569 struct x509_parse_context *ctx = context;
570 return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
571}