xref: /linux/crypto/asymmetric_keys/x509_cert_parser.c (revision eb01fe7abbe2d0b38824d2a93fdb4cc3eaf2ccc1)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* X.509 certificate parser
3  *
4  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #define pr_fmt(fmt) "X.509: "fmt
9 #include <linux/kernel.h>
10 #include <linux/export.h>
11 #include <linux/slab.h>
12 #include <linux/err.h>
13 #include <linux/oid_registry.h>
14 #include <crypto/public_key.h>
15 #include "x509_parser.h"
16 #include "x509.asn1.h"
17 #include "x509_akid.asn1.h"
18 
19 struct x509_parse_context {
20 	struct x509_certificate	*cert;		/* Certificate being constructed */
21 	unsigned long	data;			/* Start of data */
22 	const void	*key;			/* Key data */
23 	size_t		key_size;		/* Size of key data */
24 	const void	*params;		/* Key parameters */
25 	size_t		params_size;		/* Size of key parameters */
26 	enum OID	key_algo;		/* Algorithm used by the cert's key */
27 	enum OID	last_oid;		/* Last OID encountered */
28 	enum OID	sig_algo;		/* Algorithm used to sign the cert */
29 	u8		o_size;			/* Size of organizationName (O) */
30 	u8		cn_size;		/* Size of commonName (CN) */
31 	u8		email_size;		/* Size of emailAddress */
32 	u16		o_offset;		/* Offset of organizationName (O) */
33 	u16		cn_offset;		/* Offset of commonName (CN) */
34 	u16		email_offset;		/* Offset of emailAddress */
35 	unsigned	raw_akid_size;
36 	const void	*raw_akid;		/* Raw authorityKeyId in ASN.1 */
37 	const void	*akid_raw_issuer;	/* Raw directoryName in authorityKeyId */
38 	unsigned	akid_raw_issuer_size;
39 };
40 
41 /*
42  * Free an X.509 certificate
43  */
44 void x509_free_certificate(struct x509_certificate *cert)
45 {
46 	if (cert) {
47 		public_key_free(cert->pub);
48 		public_key_signature_free(cert->sig);
49 		kfree(cert->issuer);
50 		kfree(cert->subject);
51 		kfree(cert->id);
52 		kfree(cert->skid);
53 		kfree(cert);
54 	}
55 }
56 EXPORT_SYMBOL_GPL(x509_free_certificate);
57 
58 /*
59  * Parse an X.509 certificate
60  */
61 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
62 {
63 	struct x509_certificate *cert;
64 	struct x509_parse_context *ctx;
65 	struct asymmetric_key_id *kid;
66 	long ret;
67 
68 	ret = -ENOMEM;
69 	cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
70 	if (!cert)
71 		goto error_no_cert;
72 	cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
73 	if (!cert->pub)
74 		goto error_no_ctx;
75 	cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
76 	if (!cert->sig)
77 		goto error_no_ctx;
78 	ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
79 	if (!ctx)
80 		goto error_no_ctx;
81 
82 	ctx->cert = cert;
83 	ctx->data = (unsigned long)data;
84 
85 	/* Attempt to decode the certificate */
86 	ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
87 	if (ret < 0)
88 		goto error_decode;
89 
90 	/* Decode the AuthorityKeyIdentifier */
91 	if (ctx->raw_akid) {
92 		pr_devel("AKID: %u %*phN\n",
93 			 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
94 		ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
95 				       ctx->raw_akid, ctx->raw_akid_size);
96 		if (ret < 0) {
97 			pr_warn("Couldn't decode AuthKeyIdentifier\n");
98 			goto error_decode;
99 		}
100 	}
101 
102 	ret = -ENOMEM;
103 	cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
104 	if (!cert->pub->key)
105 		goto error_decode;
106 
107 	cert->pub->keylen = ctx->key_size;
108 
109 	cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
110 	if (!cert->pub->params)
111 		goto error_decode;
112 
113 	cert->pub->paramlen = ctx->params_size;
114 	cert->pub->algo = ctx->key_algo;
115 
116 	/* Grab the signature bits */
117 	ret = x509_get_sig_params(cert);
118 	if (ret < 0)
119 		goto error_decode;
120 
121 	/* Generate cert issuer + serial number key ID */
122 	kid = asymmetric_key_generate_id(cert->raw_serial,
123 					 cert->raw_serial_size,
124 					 cert->raw_issuer,
125 					 cert->raw_issuer_size);
126 	if (IS_ERR(kid)) {
127 		ret = PTR_ERR(kid);
128 		goto error_decode;
129 	}
130 	cert->id = kid;
131 
132 	/* Detect self-signed certificates */
133 	ret = x509_check_for_self_signed(cert);
134 	if (ret < 0)
135 		goto error_decode;
136 
137 	kfree(ctx);
138 	return cert;
139 
140 error_decode:
141 	kfree(ctx);
142 error_no_ctx:
143 	x509_free_certificate(cert);
144 error_no_cert:
145 	return ERR_PTR(ret);
146 }
147 EXPORT_SYMBOL_GPL(x509_cert_parse);
148 
149 /*
150  * Note an OID when we find one for later processing when we know how
151  * to interpret it.
152  */
153 int x509_note_OID(void *context, size_t hdrlen,
154 	     unsigned char tag,
155 	     const void *value, size_t vlen)
156 {
157 	struct x509_parse_context *ctx = context;
158 
159 	ctx->last_oid = look_up_OID(value, vlen);
160 	if (ctx->last_oid == OID__NR) {
161 		char buffer[50];
162 		sprint_oid(value, vlen, buffer, sizeof(buffer));
163 		pr_debug("Unknown OID: [%lu] %s\n",
164 			 (unsigned long)value - ctx->data, buffer);
165 	}
166 	return 0;
167 }
168 
169 /*
170  * Save the position of the TBS data so that we can check the signature over it
171  * later.
172  */
173 int x509_note_tbs_certificate(void *context, size_t hdrlen,
174 			      unsigned char tag,
175 			      const void *value, size_t vlen)
176 {
177 	struct x509_parse_context *ctx = context;
178 
179 	pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
180 		 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
181 
182 	ctx->cert->tbs = value - hdrlen;
183 	ctx->cert->tbs_size = vlen + hdrlen;
184 	return 0;
185 }
186 
187 /*
188  * Record the algorithm that was used to sign this certificate.
189  */
190 int x509_note_sig_algo(void *context, size_t hdrlen, unsigned char tag,
191 		       const void *value, size_t vlen)
192 {
193 	struct x509_parse_context *ctx = context;
194 
195 	pr_debug("PubKey Algo: %u\n", ctx->last_oid);
196 
197 	switch (ctx->last_oid) {
198 	default:
199 		return -ENOPKG; /* Unsupported combination */
200 
201 	case OID_sha256WithRSAEncryption:
202 		ctx->cert->sig->hash_algo = "sha256";
203 		goto rsa_pkcs1;
204 
205 	case OID_sha384WithRSAEncryption:
206 		ctx->cert->sig->hash_algo = "sha384";
207 		goto rsa_pkcs1;
208 
209 	case OID_sha512WithRSAEncryption:
210 		ctx->cert->sig->hash_algo = "sha512";
211 		goto rsa_pkcs1;
212 
213 	case OID_sha224WithRSAEncryption:
214 		ctx->cert->sig->hash_algo = "sha224";
215 		goto rsa_pkcs1;
216 
217 	case OID_id_rsassa_pkcs1_v1_5_with_sha3_256:
218 		ctx->cert->sig->hash_algo = "sha3-256";
219 		goto rsa_pkcs1;
220 
221 	case OID_id_rsassa_pkcs1_v1_5_with_sha3_384:
222 		ctx->cert->sig->hash_algo = "sha3-384";
223 		goto rsa_pkcs1;
224 
225 	case OID_id_rsassa_pkcs1_v1_5_with_sha3_512:
226 		ctx->cert->sig->hash_algo = "sha3-512";
227 		goto rsa_pkcs1;
228 
229 	case OID_id_ecdsa_with_sha224:
230 		ctx->cert->sig->hash_algo = "sha224";
231 		goto ecdsa;
232 
233 	case OID_id_ecdsa_with_sha256:
234 		ctx->cert->sig->hash_algo = "sha256";
235 		goto ecdsa;
236 
237 	case OID_id_ecdsa_with_sha384:
238 		ctx->cert->sig->hash_algo = "sha384";
239 		goto ecdsa;
240 
241 	case OID_id_ecdsa_with_sha512:
242 		ctx->cert->sig->hash_algo = "sha512";
243 		goto ecdsa;
244 
245 	case OID_id_ecdsa_with_sha3_256:
246 		ctx->cert->sig->hash_algo = "sha3-256";
247 		goto ecdsa;
248 
249 	case OID_id_ecdsa_with_sha3_384:
250 		ctx->cert->sig->hash_algo = "sha3-384";
251 		goto ecdsa;
252 
253 	case OID_id_ecdsa_with_sha3_512:
254 		ctx->cert->sig->hash_algo = "sha3-512";
255 		goto ecdsa;
256 
257 	case OID_gost2012Signature256:
258 		ctx->cert->sig->hash_algo = "streebog256";
259 		goto ecrdsa;
260 
261 	case OID_gost2012Signature512:
262 		ctx->cert->sig->hash_algo = "streebog512";
263 		goto ecrdsa;
264 
265 	case OID_SM2_with_SM3:
266 		ctx->cert->sig->hash_algo = "sm3";
267 		goto sm2;
268 	}
269 
270 rsa_pkcs1:
271 	ctx->cert->sig->pkey_algo = "rsa";
272 	ctx->cert->sig->encoding = "pkcs1";
273 	ctx->sig_algo = ctx->last_oid;
274 	return 0;
275 ecrdsa:
276 	ctx->cert->sig->pkey_algo = "ecrdsa";
277 	ctx->cert->sig->encoding = "raw";
278 	ctx->sig_algo = ctx->last_oid;
279 	return 0;
280 sm2:
281 	ctx->cert->sig->pkey_algo = "sm2";
282 	ctx->cert->sig->encoding = "raw";
283 	ctx->sig_algo = ctx->last_oid;
284 	return 0;
285 ecdsa:
286 	ctx->cert->sig->pkey_algo = "ecdsa";
287 	ctx->cert->sig->encoding = "x962";
288 	ctx->sig_algo = ctx->last_oid;
289 	return 0;
290 }
291 
292 /*
293  * Note the whereabouts and type of the signature.
294  */
295 int x509_note_signature(void *context, size_t hdrlen,
296 			unsigned char tag,
297 			const void *value, size_t vlen)
298 {
299 	struct x509_parse_context *ctx = context;
300 
301 	pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
302 
303 	/*
304 	 * In X.509 certificates, the signature's algorithm is stored in two
305 	 * places: inside the TBSCertificate (the data that is signed), and
306 	 * alongside the signature.  These *must* match.
307 	 */
308 	if (ctx->last_oid != ctx->sig_algo) {
309 		pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
310 			ctx->last_oid, ctx->sig_algo);
311 		return -EINVAL;
312 	}
313 
314 	if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
315 	    strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
316 	    strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
317 	    strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
318 		/* Discard the BIT STRING metadata */
319 		if (vlen < 1 || *(const u8 *)value != 0)
320 			return -EBADMSG;
321 
322 		value++;
323 		vlen--;
324 	}
325 
326 	ctx->cert->raw_sig = value;
327 	ctx->cert->raw_sig_size = vlen;
328 	return 0;
329 }
330 
331 /*
332  * Note the certificate serial number
333  */
334 int x509_note_serial(void *context, size_t hdrlen,
335 		     unsigned char tag,
336 		     const void *value, size_t vlen)
337 {
338 	struct x509_parse_context *ctx = context;
339 	ctx->cert->raw_serial = value;
340 	ctx->cert->raw_serial_size = vlen;
341 	return 0;
342 }
343 
344 /*
345  * Note some of the name segments from which we'll fabricate a name.
346  */
347 int x509_extract_name_segment(void *context, size_t hdrlen,
348 			      unsigned char tag,
349 			      const void *value, size_t vlen)
350 {
351 	struct x509_parse_context *ctx = context;
352 
353 	switch (ctx->last_oid) {
354 	case OID_commonName:
355 		ctx->cn_size = vlen;
356 		ctx->cn_offset = (unsigned long)value - ctx->data;
357 		break;
358 	case OID_organizationName:
359 		ctx->o_size = vlen;
360 		ctx->o_offset = (unsigned long)value - ctx->data;
361 		break;
362 	case OID_email_address:
363 		ctx->email_size = vlen;
364 		ctx->email_offset = (unsigned long)value - ctx->data;
365 		break;
366 	default:
367 		break;
368 	}
369 
370 	return 0;
371 }
372 
373 /*
374  * Fabricate and save the issuer and subject names
375  */
376 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
377 			       unsigned char tag,
378 			       char **_name, size_t vlen)
379 {
380 	const void *name, *data = (const void *)ctx->data;
381 	size_t namesize;
382 	char *buffer;
383 
384 	if (*_name)
385 		return -EINVAL;
386 
387 	/* Empty name string if no material */
388 	if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
389 		buffer = kmalloc(1, GFP_KERNEL);
390 		if (!buffer)
391 			return -ENOMEM;
392 		buffer[0] = 0;
393 		goto done;
394 	}
395 
396 	if (ctx->cn_size && ctx->o_size) {
397 		/* Consider combining O and CN, but use only the CN if it is
398 		 * prefixed by the O, or a significant portion thereof.
399 		 */
400 		namesize = ctx->cn_size;
401 		name = data + ctx->cn_offset;
402 		if (ctx->cn_size >= ctx->o_size &&
403 		    memcmp(data + ctx->cn_offset, data + ctx->o_offset,
404 			   ctx->o_size) == 0)
405 			goto single_component;
406 		if (ctx->cn_size >= 7 &&
407 		    ctx->o_size >= 7 &&
408 		    memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
409 			goto single_component;
410 
411 		buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
412 				 GFP_KERNEL);
413 		if (!buffer)
414 			return -ENOMEM;
415 
416 		memcpy(buffer,
417 		       data + ctx->o_offset, ctx->o_size);
418 		buffer[ctx->o_size + 0] = ':';
419 		buffer[ctx->o_size + 1] = ' ';
420 		memcpy(buffer + ctx->o_size + 2,
421 		       data + ctx->cn_offset, ctx->cn_size);
422 		buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
423 		goto done;
424 
425 	} else if (ctx->cn_size) {
426 		namesize = ctx->cn_size;
427 		name = data + ctx->cn_offset;
428 	} else if (ctx->o_size) {
429 		namesize = ctx->o_size;
430 		name = data + ctx->o_offset;
431 	} else {
432 		namesize = ctx->email_size;
433 		name = data + ctx->email_offset;
434 	}
435 
436 single_component:
437 	buffer = kmalloc(namesize + 1, GFP_KERNEL);
438 	if (!buffer)
439 		return -ENOMEM;
440 	memcpy(buffer, name, namesize);
441 	buffer[namesize] = 0;
442 
443 done:
444 	*_name = buffer;
445 	ctx->cn_size = 0;
446 	ctx->o_size = 0;
447 	ctx->email_size = 0;
448 	return 0;
449 }
450 
451 int x509_note_issuer(void *context, size_t hdrlen,
452 		     unsigned char tag,
453 		     const void *value, size_t vlen)
454 {
455 	struct x509_parse_context *ctx = context;
456 	struct asymmetric_key_id *kid;
457 
458 	ctx->cert->raw_issuer = value;
459 	ctx->cert->raw_issuer_size = vlen;
460 
461 	if (!ctx->cert->sig->auth_ids[2]) {
462 		kid = asymmetric_key_generate_id(value, vlen, "", 0);
463 		if (IS_ERR(kid))
464 			return PTR_ERR(kid);
465 		ctx->cert->sig->auth_ids[2] = kid;
466 	}
467 
468 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
469 }
470 
471 int x509_note_subject(void *context, size_t hdrlen,
472 		      unsigned char tag,
473 		      const void *value, size_t vlen)
474 {
475 	struct x509_parse_context *ctx = context;
476 	ctx->cert->raw_subject = value;
477 	ctx->cert->raw_subject_size = vlen;
478 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
479 }
480 
481 /*
482  * Extract the parameters for the public key
483  */
484 int x509_note_params(void *context, size_t hdrlen,
485 		     unsigned char tag,
486 		     const void *value, size_t vlen)
487 {
488 	struct x509_parse_context *ctx = context;
489 
490 	/*
491 	 * AlgorithmIdentifier is used three times in the x509, we should skip
492 	 * first and ignore third, using second one which is after subject and
493 	 * before subjectPublicKey.
494 	 */
495 	if (!ctx->cert->raw_subject || ctx->key)
496 		return 0;
497 	ctx->params = value - hdrlen;
498 	ctx->params_size = vlen + hdrlen;
499 	return 0;
500 }
501 
502 /*
503  * Extract the data for the public key algorithm
504  */
505 int x509_extract_key_data(void *context, size_t hdrlen,
506 			  unsigned char tag,
507 			  const void *value, size_t vlen)
508 {
509 	struct x509_parse_context *ctx = context;
510 	enum OID oid;
511 
512 	ctx->key_algo = ctx->last_oid;
513 	switch (ctx->last_oid) {
514 	case OID_rsaEncryption:
515 		ctx->cert->pub->pkey_algo = "rsa";
516 		break;
517 	case OID_gost2012PKey256:
518 	case OID_gost2012PKey512:
519 		ctx->cert->pub->pkey_algo = "ecrdsa";
520 		break;
521 	case OID_sm2:
522 		ctx->cert->pub->pkey_algo = "sm2";
523 		break;
524 	case OID_id_ecPublicKey:
525 		if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
526 			return -EBADMSG;
527 
528 		switch (oid) {
529 		case OID_sm2:
530 			ctx->cert->pub->pkey_algo = "sm2";
531 			break;
532 		case OID_id_prime192v1:
533 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
534 			break;
535 		case OID_id_prime256v1:
536 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
537 			break;
538 		case OID_id_ansip384r1:
539 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
540 			break;
541 		default:
542 			return -ENOPKG;
543 		}
544 		break;
545 	default:
546 		return -ENOPKG;
547 	}
548 
549 	/* Discard the BIT STRING metadata */
550 	if (vlen < 1 || *(const u8 *)value != 0)
551 		return -EBADMSG;
552 	ctx->key = value + 1;
553 	ctx->key_size = vlen - 1;
554 	return 0;
555 }
556 
557 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
558 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
559 
560 /*
561  * Process certificate extensions that are used to qualify the certificate.
562  */
563 int x509_process_extension(void *context, size_t hdrlen,
564 			   unsigned char tag,
565 			   const void *value, size_t vlen)
566 {
567 	struct x509_parse_context *ctx = context;
568 	struct asymmetric_key_id *kid;
569 	const unsigned char *v = value;
570 
571 	pr_debug("Extension: %u\n", ctx->last_oid);
572 
573 	if (ctx->last_oid == OID_subjectKeyIdentifier) {
574 		/* Get hold of the key fingerprint */
575 		if (ctx->cert->skid || vlen < 3)
576 			return -EBADMSG;
577 		if (v[0] != ASN1_OTS || v[1] != vlen - 2)
578 			return -EBADMSG;
579 		v += 2;
580 		vlen -= 2;
581 
582 		ctx->cert->raw_skid_size = vlen;
583 		ctx->cert->raw_skid = v;
584 		kid = asymmetric_key_generate_id(v, vlen, "", 0);
585 		if (IS_ERR(kid))
586 			return PTR_ERR(kid);
587 		ctx->cert->skid = kid;
588 		pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
589 		return 0;
590 	}
591 
592 	if (ctx->last_oid == OID_keyUsage) {
593 		/*
594 		 * Get hold of the keyUsage bit string
595 		 * v[1] is the encoding size
596 		 *       (Expect either 0x02 or 0x03, making it 1 or 2 bytes)
597 		 * v[2] is the number of unused bits in the bit string
598 		 *       (If >= 3 keyCertSign is missing when v[1] = 0x02)
599 		 * v[3] and possibly v[4] contain the bit string
600 		 *
601 		 * From RFC 5280 4.2.1.3:
602 		 *   0x04 is where keyCertSign lands in this bit string
603 		 *   0x80 is where digitalSignature lands in this bit string
604 		 */
605 		if (v[0] != ASN1_BTS)
606 			return -EBADMSG;
607 		if (vlen < 4)
608 			return -EBADMSG;
609 		if (v[2] >= 8)
610 			return -EBADMSG;
611 		if (v[3] & 0x80)
612 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG;
613 		if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04))
614 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
615 		else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04))
616 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
617 		return 0;
618 	}
619 
620 	if (ctx->last_oid == OID_authorityKeyIdentifier) {
621 		/* Get hold of the CA key fingerprint */
622 		ctx->raw_akid = v;
623 		ctx->raw_akid_size = vlen;
624 		return 0;
625 	}
626 
627 	if (ctx->last_oid == OID_basicConstraints) {
628 		/*
629 		 * Get hold of the basicConstraints
630 		 * v[1] is the encoding size
631 		 *	(Expect 0x2 or greater, making it 1 or more bytes)
632 		 * v[2] is the encoding type
633 		 *	(Expect an ASN1_BOOL for the CA)
634 		 * v[3] is the contents of the ASN1_BOOL
635 		 *      (Expect 1 if the CA is TRUE)
636 		 * vlen should match the entire extension size
637 		 */
638 		if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
639 			return -EBADMSG;
640 		if (vlen < 2)
641 			return -EBADMSG;
642 		if (v[1] != vlen - 2)
643 			return -EBADMSG;
644 		if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
645 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA;
646 		return 0;
647 	}
648 
649 	return 0;
650 }
651 
652 /**
653  * x509_decode_time - Decode an X.509 time ASN.1 object
654  * @_t: The time to fill in
655  * @hdrlen: The length of the object header
656  * @tag: The object tag
657  * @value: The object value
658  * @vlen: The size of the object value
659  *
660  * Decode an ASN.1 universal time or generalised time field into a struct the
661  * kernel can handle and check it for validity.  The time is decoded thus:
662  *
663  *	[RFC5280 §4.1.2.5]
664  *	CAs conforming to this profile MUST always encode certificate validity
665  *	dates through the year 2049 as UTCTime; certificate validity dates in
666  *	2050 or later MUST be encoded as GeneralizedTime.  Conforming
667  *	applications MUST be able to process validity dates that are encoded in
668  *	either UTCTime or GeneralizedTime.
669  */
670 int x509_decode_time(time64_t *_t,  size_t hdrlen,
671 		     unsigned char tag,
672 		     const unsigned char *value, size_t vlen)
673 {
674 	static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
675 						       31, 31, 30, 31, 30, 31 };
676 	const unsigned char *p = value;
677 	unsigned year, mon, day, hour, min, sec, mon_len;
678 
679 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
680 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
681 
682 	if (tag == ASN1_UNITIM) {
683 		/* UTCTime: YYMMDDHHMMSSZ */
684 		if (vlen != 13)
685 			goto unsupported_time;
686 		year = DD2bin(p);
687 		if (year >= 50)
688 			year += 1900;
689 		else
690 			year += 2000;
691 	} else if (tag == ASN1_GENTIM) {
692 		/* GenTime: YYYYMMDDHHMMSSZ */
693 		if (vlen != 15)
694 			goto unsupported_time;
695 		year = DD2bin(p) * 100 + DD2bin(p);
696 		if (year >= 1950 && year <= 2049)
697 			goto invalid_time;
698 	} else {
699 		goto unsupported_time;
700 	}
701 
702 	mon  = DD2bin(p);
703 	day = DD2bin(p);
704 	hour = DD2bin(p);
705 	min  = DD2bin(p);
706 	sec  = DD2bin(p);
707 
708 	if (*p != 'Z')
709 		goto unsupported_time;
710 
711 	if (year < 1970 ||
712 	    mon < 1 || mon > 12)
713 		goto invalid_time;
714 
715 	mon_len = month_lengths[mon - 1];
716 	if (mon == 2) {
717 		if (year % 4 == 0) {
718 			mon_len = 29;
719 			if (year % 100 == 0) {
720 				mon_len = 28;
721 				if (year % 400 == 0)
722 					mon_len = 29;
723 			}
724 		}
725 	}
726 
727 	if (day < 1 || day > mon_len ||
728 	    hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
729 	    min > 59 ||
730 	    sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
731 		goto invalid_time;
732 
733 	*_t = mktime64(year, mon, day, hour, min, sec);
734 	return 0;
735 
736 unsupported_time:
737 	pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
738 		 tag, (int)vlen, value);
739 	return -EBADMSG;
740 invalid_time:
741 	pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
742 		 tag, (int)vlen, value);
743 	return -EBADMSG;
744 }
745 EXPORT_SYMBOL_GPL(x509_decode_time);
746 
747 int x509_note_not_before(void *context, size_t hdrlen,
748 			 unsigned char tag,
749 			 const void *value, size_t vlen)
750 {
751 	struct x509_parse_context *ctx = context;
752 	return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
753 }
754 
755 int x509_note_not_after(void *context, size_t hdrlen,
756 			unsigned char tag,
757 			const void *value, size_t vlen)
758 {
759 	struct x509_parse_context *ctx = context;
760 	return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
761 }
762 
763 /*
764  * Note a key identifier-based AuthorityKeyIdentifier
765  */
766 int x509_akid_note_kid(void *context, size_t hdrlen,
767 		       unsigned char tag,
768 		       const void *value, size_t vlen)
769 {
770 	struct x509_parse_context *ctx = context;
771 	struct asymmetric_key_id *kid;
772 
773 	pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
774 
775 	if (ctx->cert->sig->auth_ids[1])
776 		return 0;
777 
778 	kid = asymmetric_key_generate_id(value, vlen, "", 0);
779 	if (IS_ERR(kid))
780 		return PTR_ERR(kid);
781 	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
782 	ctx->cert->sig->auth_ids[1] = kid;
783 	return 0;
784 }
785 
786 /*
787  * Note a directoryName in an AuthorityKeyIdentifier
788  */
789 int x509_akid_note_name(void *context, size_t hdrlen,
790 			unsigned char tag,
791 			const void *value, size_t vlen)
792 {
793 	struct x509_parse_context *ctx = context;
794 
795 	pr_debug("AKID: name: %*phN\n", (int)vlen, value);
796 
797 	ctx->akid_raw_issuer = value;
798 	ctx->akid_raw_issuer_size = vlen;
799 	return 0;
800 }
801 
802 /*
803  * Note a serial number in an AuthorityKeyIdentifier
804  */
805 int x509_akid_note_serial(void *context, size_t hdrlen,
806 			  unsigned char tag,
807 			  const void *value, size_t vlen)
808 {
809 	struct x509_parse_context *ctx = context;
810 	struct asymmetric_key_id *kid;
811 
812 	pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
813 
814 	if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
815 		return 0;
816 
817 	kid = asymmetric_key_generate_id(value,
818 					 vlen,
819 					 ctx->akid_raw_issuer,
820 					 ctx->akid_raw_issuer_size);
821 	if (IS_ERR(kid))
822 		return PTR_ERR(kid);
823 
824 	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
825 	ctx->cert->sig->auth_ids[0] = kid;
826 	return 0;
827 }
828