xref: /linux/crypto/asymmetric_keys/x509_cert_parser.c (revision 0ce92d548b44649a8de706f9bb9e74a4ed2f18a7)
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 __free(x509_free_certificate);
64 	struct x509_parse_context *ctx __free(kfree) = NULL;
65 	struct asymmetric_key_id *kid;
66 	long ret;
67 
68 	cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
69 	if (!cert)
70 		return ERR_PTR(-ENOMEM);
71 	cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
72 	if (!cert->pub)
73 		return ERR_PTR(-ENOMEM);
74 	cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
75 	if (!cert->sig)
76 		return ERR_PTR(-ENOMEM);
77 	ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
78 	if (!ctx)
79 		return ERR_PTR(-ENOMEM);
80 
81 	ctx->cert = cert;
82 	ctx->data = (unsigned long)data;
83 
84 	/* Attempt to decode the certificate */
85 	ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
86 	if (ret < 0)
87 		return ERR_PTR(ret);
88 
89 	/* Decode the AuthorityKeyIdentifier */
90 	if (ctx->raw_akid) {
91 		pr_devel("AKID: %u %*phN\n",
92 			 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
93 		ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
94 				       ctx->raw_akid, ctx->raw_akid_size);
95 		if (ret < 0) {
96 			pr_warn("Couldn't decode AuthKeyIdentifier\n");
97 			return ERR_PTR(ret);
98 		}
99 	}
100 
101 	cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
102 	if (!cert->pub->key)
103 		return ERR_PTR(-ENOMEM);
104 
105 	cert->pub->keylen = ctx->key_size;
106 
107 	cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
108 	if (!cert->pub->params)
109 		return ERR_PTR(-ENOMEM);
110 
111 	cert->pub->paramlen = ctx->params_size;
112 	cert->pub->algo = ctx->key_algo;
113 
114 	/* Grab the signature bits */
115 	ret = x509_get_sig_params(cert);
116 	if (ret < 0)
117 		return ERR_PTR(ret);
118 
119 	/* Generate cert issuer + serial number key ID */
120 	kid = asymmetric_key_generate_id(cert->raw_serial,
121 					 cert->raw_serial_size,
122 					 cert->raw_issuer,
123 					 cert->raw_issuer_size);
124 	if (IS_ERR(kid))
125 		return ERR_CAST(kid);
126 	cert->id = kid;
127 
128 	/* Detect self-signed certificates */
129 	ret = x509_check_for_self_signed(cert);
130 	if (ret < 0)
131 		return ERR_PTR(ret);
132 
133 	return_ptr(cert);
134 }
135 EXPORT_SYMBOL_GPL(x509_cert_parse);
136 
137 /*
138  * Note an OID when we find one for later processing when we know how
139  * to interpret it.
140  */
141 int x509_note_OID(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 	ctx->last_oid = look_up_OID(value, vlen);
148 	if (ctx->last_oid == OID__NR) {
149 		char buffer[50];
150 		sprint_oid(value, vlen, buffer, sizeof(buffer));
151 		pr_debug("Unknown OID: [%lu] %s\n",
152 			 (unsigned long)value - ctx->data, buffer);
153 	}
154 	return 0;
155 }
156 
157 /*
158  * Save the position of the TBS data so that we can check the signature over it
159  * later.
160  */
161 int x509_note_tbs_certificate(void *context, size_t hdrlen,
162 			      unsigned char tag,
163 			      const void *value, size_t vlen)
164 {
165 	struct x509_parse_context *ctx = context;
166 
167 	pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
168 		 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
169 
170 	ctx->cert->tbs = value - hdrlen;
171 	ctx->cert->tbs_size = vlen + hdrlen;
172 	return 0;
173 }
174 
175 /*
176  * Record the algorithm that was used to sign this certificate.
177  */
178 int x509_note_sig_algo(void *context, size_t hdrlen, unsigned char tag,
179 		       const void *value, size_t vlen)
180 {
181 	struct x509_parse_context *ctx = context;
182 
183 	pr_debug("PubKey Algo: %u\n", ctx->last_oid);
184 
185 	switch (ctx->last_oid) {
186 	default:
187 		return -ENOPKG; /* Unsupported combination */
188 
189 	case OID_sha1WithRSAEncryption:
190 		ctx->cert->sig->hash_algo = "sha1";
191 		goto rsa_pkcs1;
192 
193 	case OID_sha256WithRSAEncryption:
194 		ctx->cert->sig->hash_algo = "sha256";
195 		goto rsa_pkcs1;
196 
197 	case OID_sha384WithRSAEncryption:
198 		ctx->cert->sig->hash_algo = "sha384";
199 		goto rsa_pkcs1;
200 
201 	case OID_sha512WithRSAEncryption:
202 		ctx->cert->sig->hash_algo = "sha512";
203 		goto rsa_pkcs1;
204 
205 	case OID_sha224WithRSAEncryption:
206 		ctx->cert->sig->hash_algo = "sha224";
207 		goto rsa_pkcs1;
208 
209 	case OID_id_ecdsa_with_sha1:
210 		ctx->cert->sig->hash_algo = "sha1";
211 		goto ecdsa;
212 
213 	case OID_id_rsassa_pkcs1_v1_5_with_sha3_256:
214 		ctx->cert->sig->hash_algo = "sha3-256";
215 		goto rsa_pkcs1;
216 
217 	case OID_id_rsassa_pkcs1_v1_5_with_sha3_384:
218 		ctx->cert->sig->hash_algo = "sha3-384";
219 		goto rsa_pkcs1;
220 
221 	case OID_id_rsassa_pkcs1_v1_5_with_sha3_512:
222 		ctx->cert->sig->hash_algo = "sha3-512";
223 		goto rsa_pkcs1;
224 
225 	case OID_id_ecdsa_with_sha224:
226 		ctx->cert->sig->hash_algo = "sha224";
227 		goto ecdsa;
228 
229 	case OID_id_ecdsa_with_sha256:
230 		ctx->cert->sig->hash_algo = "sha256";
231 		goto ecdsa;
232 
233 	case OID_id_ecdsa_with_sha384:
234 		ctx->cert->sig->hash_algo = "sha384";
235 		goto ecdsa;
236 
237 	case OID_id_ecdsa_with_sha512:
238 		ctx->cert->sig->hash_algo = "sha512";
239 		goto ecdsa;
240 
241 	case OID_id_ecdsa_with_sha3_256:
242 		ctx->cert->sig->hash_algo = "sha3-256";
243 		goto ecdsa;
244 
245 	case OID_id_ecdsa_with_sha3_384:
246 		ctx->cert->sig->hash_algo = "sha3-384";
247 		goto ecdsa;
248 
249 	case OID_id_ecdsa_with_sha3_512:
250 		ctx->cert->sig->hash_algo = "sha3-512";
251 		goto ecdsa;
252 
253 	case OID_gost2012Signature256:
254 		ctx->cert->sig->hash_algo = "streebog256";
255 		goto ecrdsa;
256 
257 	case OID_gost2012Signature512:
258 		ctx->cert->sig->hash_algo = "streebog512";
259 		goto ecrdsa;
260 	}
261 
262 rsa_pkcs1:
263 	ctx->cert->sig->pkey_algo = "rsa";
264 	ctx->cert->sig->encoding = "pkcs1";
265 	ctx->sig_algo = ctx->last_oid;
266 	return 0;
267 ecrdsa:
268 	ctx->cert->sig->pkey_algo = "ecrdsa";
269 	ctx->cert->sig->encoding = "raw";
270 	ctx->sig_algo = ctx->last_oid;
271 	return 0;
272 ecdsa:
273 	ctx->cert->sig->pkey_algo = "ecdsa";
274 	ctx->cert->sig->encoding = "x962";
275 	ctx->sig_algo = ctx->last_oid;
276 	return 0;
277 }
278 
279 /*
280  * Note the whereabouts and type of the signature.
281  */
282 int x509_note_signature(void *context, size_t hdrlen,
283 			unsigned char tag,
284 			const void *value, size_t vlen)
285 {
286 	struct x509_parse_context *ctx = context;
287 
288 	pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
289 
290 	/*
291 	 * In X.509 certificates, the signature's algorithm is stored in two
292 	 * places: inside the TBSCertificate (the data that is signed), and
293 	 * alongside the signature.  These *must* match.
294 	 */
295 	if (ctx->last_oid != ctx->sig_algo) {
296 		pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
297 			ctx->last_oid, ctx->sig_algo);
298 		return -EINVAL;
299 	}
300 
301 	if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
302 	    strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
303 	    strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
304 		/* Discard the BIT STRING metadata */
305 		if (vlen < 1 || *(const u8 *)value != 0)
306 			return -EBADMSG;
307 
308 		value++;
309 		vlen--;
310 	}
311 
312 	ctx->cert->raw_sig = value;
313 	ctx->cert->raw_sig_size = vlen;
314 	return 0;
315 }
316 
317 /*
318  * Note the certificate serial number
319  */
320 int x509_note_serial(void *context, size_t hdrlen,
321 		     unsigned char tag,
322 		     const void *value, size_t vlen)
323 {
324 	struct x509_parse_context *ctx = context;
325 	ctx->cert->raw_serial = value;
326 	ctx->cert->raw_serial_size = vlen;
327 	return 0;
328 }
329 
330 /*
331  * Note some of the name segments from which we'll fabricate a name.
332  */
333 int x509_extract_name_segment(void *context, size_t hdrlen,
334 			      unsigned char tag,
335 			      const void *value, size_t vlen)
336 {
337 	struct x509_parse_context *ctx = context;
338 
339 	switch (ctx->last_oid) {
340 	case OID_commonName:
341 		ctx->cn_size = vlen;
342 		ctx->cn_offset = (unsigned long)value - ctx->data;
343 		break;
344 	case OID_organizationName:
345 		ctx->o_size = vlen;
346 		ctx->o_offset = (unsigned long)value - ctx->data;
347 		break;
348 	case OID_email_address:
349 		ctx->email_size = vlen;
350 		ctx->email_offset = (unsigned long)value - ctx->data;
351 		break;
352 	default:
353 		break;
354 	}
355 
356 	return 0;
357 }
358 
359 /*
360  * Fabricate and save the issuer and subject names
361  */
362 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
363 			       unsigned char tag,
364 			       char **_name, size_t vlen)
365 {
366 	const void *name, *data = (const void *)ctx->data;
367 	size_t namesize;
368 	char *buffer;
369 
370 	if (*_name)
371 		return -EINVAL;
372 
373 	/* Empty name string if no material */
374 	if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
375 		buffer = kzalloc(1, GFP_KERNEL);
376 		if (!buffer)
377 			return -ENOMEM;
378 		goto done;
379 	}
380 
381 	if (ctx->cn_size && ctx->o_size) {
382 		/* Consider combining O and CN, but use only the CN if it is
383 		 * prefixed by the O, or a significant portion thereof.
384 		 */
385 		namesize = ctx->cn_size;
386 		name = data + ctx->cn_offset;
387 		if (ctx->cn_size >= ctx->o_size &&
388 		    memcmp(data + ctx->cn_offset, data + ctx->o_offset,
389 			   ctx->o_size) == 0)
390 			goto single_component;
391 		if (ctx->cn_size >= 7 &&
392 		    ctx->o_size >= 7 &&
393 		    memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
394 			goto single_component;
395 
396 		buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
397 				 GFP_KERNEL);
398 		if (!buffer)
399 			return -ENOMEM;
400 
401 		memcpy(buffer,
402 		       data + ctx->o_offset, ctx->o_size);
403 		buffer[ctx->o_size + 0] = ':';
404 		buffer[ctx->o_size + 1] = ' ';
405 		memcpy(buffer + ctx->o_size + 2,
406 		       data + ctx->cn_offset, ctx->cn_size);
407 		buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
408 		goto done;
409 
410 	} else if (ctx->cn_size) {
411 		namesize = ctx->cn_size;
412 		name = data + ctx->cn_offset;
413 	} else if (ctx->o_size) {
414 		namesize = ctx->o_size;
415 		name = data + ctx->o_offset;
416 	} else {
417 		namesize = ctx->email_size;
418 		name = data + ctx->email_offset;
419 	}
420 
421 single_component:
422 	buffer = kmalloc(namesize + 1, GFP_KERNEL);
423 	if (!buffer)
424 		return -ENOMEM;
425 	memcpy(buffer, name, namesize);
426 	buffer[namesize] = 0;
427 
428 done:
429 	*_name = buffer;
430 	ctx->cn_size = 0;
431 	ctx->o_size = 0;
432 	ctx->email_size = 0;
433 	return 0;
434 }
435 
436 int x509_note_issuer(void *context, size_t hdrlen,
437 		     unsigned char tag,
438 		     const void *value, size_t vlen)
439 {
440 	struct x509_parse_context *ctx = context;
441 	struct asymmetric_key_id *kid;
442 
443 	ctx->cert->raw_issuer = value;
444 	ctx->cert->raw_issuer_size = vlen;
445 
446 	if (!ctx->cert->sig->auth_ids[2]) {
447 		kid = asymmetric_key_generate_id(value, vlen, "", 0);
448 		if (IS_ERR(kid))
449 			return PTR_ERR(kid);
450 		ctx->cert->sig->auth_ids[2] = kid;
451 	}
452 
453 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
454 }
455 
456 int x509_note_subject(void *context, size_t hdrlen,
457 		      unsigned char tag,
458 		      const void *value, size_t vlen)
459 {
460 	struct x509_parse_context *ctx = context;
461 	ctx->cert->raw_subject = value;
462 	ctx->cert->raw_subject_size = vlen;
463 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
464 }
465 
466 /*
467  * Extract the parameters for the public key
468  */
469 int x509_note_params(void *context, size_t hdrlen,
470 		     unsigned char tag,
471 		     const void *value, size_t vlen)
472 {
473 	struct x509_parse_context *ctx = context;
474 
475 	/*
476 	 * AlgorithmIdentifier is used three times in the x509, we should skip
477 	 * first and ignore third, using second one which is after subject and
478 	 * before subjectPublicKey.
479 	 */
480 	if (!ctx->cert->raw_subject || ctx->key)
481 		return 0;
482 	ctx->params = value - hdrlen;
483 	ctx->params_size = vlen + hdrlen;
484 	return 0;
485 }
486 
487 /*
488  * Extract the data for the public key algorithm
489  */
490 int x509_extract_key_data(void *context, size_t hdrlen,
491 			  unsigned char tag,
492 			  const void *value, size_t vlen)
493 {
494 	struct x509_parse_context *ctx = context;
495 	enum OID oid;
496 
497 	ctx->key_algo = ctx->last_oid;
498 	switch (ctx->last_oid) {
499 	case OID_rsaEncryption:
500 		ctx->cert->pub->pkey_algo = "rsa";
501 		break;
502 	case OID_gost2012PKey256:
503 	case OID_gost2012PKey512:
504 		ctx->cert->pub->pkey_algo = "ecrdsa";
505 		break;
506 	case OID_id_ecPublicKey:
507 		if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
508 			return -EBADMSG;
509 
510 		switch (oid) {
511 		case OID_id_prime192v1:
512 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
513 			break;
514 		case OID_id_prime256v1:
515 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
516 			break;
517 		case OID_id_ansip384r1:
518 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
519 			break;
520 		case OID_id_ansip521r1:
521 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p521";
522 			break;
523 		default:
524 			return -ENOPKG;
525 		}
526 		break;
527 	default:
528 		return -ENOPKG;
529 	}
530 
531 	/* Discard the BIT STRING metadata */
532 	if (vlen < 1 || *(const u8 *)value != 0)
533 		return -EBADMSG;
534 	ctx->key = value + 1;
535 	ctx->key_size = vlen - 1;
536 	return 0;
537 }
538 
539 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
540 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
541 
542 /*
543  * Process certificate extensions that are used to qualify the certificate.
544  */
545 int x509_process_extension(void *context, size_t hdrlen,
546 			   unsigned char tag,
547 			   const void *value, size_t vlen)
548 {
549 	struct x509_parse_context *ctx = context;
550 	struct asymmetric_key_id *kid;
551 	const unsigned char *v = value;
552 
553 	pr_debug("Extension: %u\n", ctx->last_oid);
554 
555 	if (ctx->last_oid == OID_subjectKeyIdentifier) {
556 		/* Get hold of the key fingerprint */
557 		if (ctx->cert->skid || vlen < 3)
558 			return -EBADMSG;
559 		if (v[0] != ASN1_OTS || v[1] != vlen - 2)
560 			return -EBADMSG;
561 		v += 2;
562 		vlen -= 2;
563 
564 		ctx->cert->raw_skid_size = vlen;
565 		ctx->cert->raw_skid = v;
566 		kid = asymmetric_key_generate_id(v, vlen, "", 0);
567 		if (IS_ERR(kid))
568 			return PTR_ERR(kid);
569 		ctx->cert->skid = kid;
570 		pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
571 		return 0;
572 	}
573 
574 	if (ctx->last_oid == OID_keyUsage) {
575 		/*
576 		 * Get hold of the keyUsage bit string
577 		 * v[1] is the encoding size
578 		 *       (Expect either 0x02 or 0x03, making it 1 or 2 bytes)
579 		 * v[2] is the number of unused bits in the bit string
580 		 *       (If >= 3 keyCertSign is missing when v[1] = 0x02)
581 		 * v[3] and possibly v[4] contain the bit string
582 		 *
583 		 * From RFC 5280 4.2.1.3:
584 		 *   0x04 is where keyCertSign lands in this bit string
585 		 *   0x80 is where digitalSignature lands in this bit string
586 		 */
587 		if (v[0] != ASN1_BTS)
588 			return -EBADMSG;
589 		if (vlen < 4)
590 			return -EBADMSG;
591 		if (v[2] >= 8)
592 			return -EBADMSG;
593 		if (v[3] & 0x80)
594 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG;
595 		if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04))
596 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
597 		else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04))
598 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
599 		return 0;
600 	}
601 
602 	if (ctx->last_oid == OID_authorityKeyIdentifier) {
603 		/* Get hold of the CA key fingerprint */
604 		ctx->raw_akid = v;
605 		ctx->raw_akid_size = vlen;
606 		return 0;
607 	}
608 
609 	if (ctx->last_oid == OID_basicConstraints) {
610 		/*
611 		 * Get hold of the basicConstraints
612 		 * v[1] is the encoding size
613 		 *	(Expect 0x2 or greater, making it 1 or more bytes)
614 		 * v[2] is the encoding type
615 		 *	(Expect an ASN1_BOOL for the CA)
616 		 * v[3] is the contents of the ASN1_BOOL
617 		 *      (Expect 1 if the CA is TRUE)
618 		 * vlen should match the entire extension size
619 		 */
620 		if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
621 			return -EBADMSG;
622 		if (vlen < 2)
623 			return -EBADMSG;
624 		if (v[1] != vlen - 2)
625 			return -EBADMSG;
626 		if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
627 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA;
628 		return 0;
629 	}
630 
631 	return 0;
632 }
633 
634 /**
635  * x509_decode_time - Decode an X.509 time ASN.1 object
636  * @_t: The time to fill in
637  * @hdrlen: The length of the object header
638  * @tag: The object tag
639  * @value: The object value
640  * @vlen: The size of the object value
641  *
642  * Decode an ASN.1 universal time or generalised time field into a struct the
643  * kernel can handle and check it for validity.  The time is decoded thus:
644  *
645  *	[RFC5280 §4.1.2.5]
646  *	CAs conforming to this profile MUST always encode certificate validity
647  *	dates through the year 2049 as UTCTime; certificate validity dates in
648  *	2050 or later MUST be encoded as GeneralizedTime.  Conforming
649  *	applications MUST be able to process validity dates that are encoded in
650  *	either UTCTime or GeneralizedTime.
651  */
652 int x509_decode_time(time64_t *_t,  size_t hdrlen,
653 		     unsigned char tag,
654 		     const unsigned char *value, size_t vlen)
655 {
656 	static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
657 						       31, 31, 30, 31, 30, 31 };
658 	const unsigned char *p = value;
659 	unsigned year, mon, day, hour, min, sec, mon_len;
660 
661 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
662 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
663 
664 	if (tag == ASN1_UNITIM) {
665 		/* UTCTime: YYMMDDHHMMSSZ */
666 		if (vlen != 13)
667 			goto unsupported_time;
668 		year = DD2bin(p);
669 		if (year >= 50)
670 			year += 1900;
671 		else
672 			year += 2000;
673 	} else if (tag == ASN1_GENTIM) {
674 		/* GenTime: YYYYMMDDHHMMSSZ */
675 		if (vlen != 15)
676 			goto unsupported_time;
677 		year = DD2bin(p) * 100 + DD2bin(p);
678 		if (year >= 1950 && year <= 2049)
679 			goto invalid_time;
680 	} else {
681 		goto unsupported_time;
682 	}
683 
684 	mon  = DD2bin(p);
685 	day = DD2bin(p);
686 	hour = DD2bin(p);
687 	min  = DD2bin(p);
688 	sec  = DD2bin(p);
689 
690 	if (*p != 'Z')
691 		goto unsupported_time;
692 
693 	if (year < 1970 ||
694 	    mon < 1 || mon > 12)
695 		goto invalid_time;
696 
697 	mon_len = month_lengths[mon - 1];
698 	if (mon == 2) {
699 		if (year % 4 == 0) {
700 			mon_len = 29;
701 			if (year % 100 == 0) {
702 				mon_len = 28;
703 				if (year % 400 == 0)
704 					mon_len = 29;
705 			}
706 		}
707 	}
708 
709 	if (day < 1 || day > mon_len ||
710 	    hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
711 	    min > 59 ||
712 	    sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
713 		goto invalid_time;
714 
715 	*_t = mktime64(year, mon, day, hour, min, sec);
716 	return 0;
717 
718 unsupported_time:
719 	pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
720 		 tag, (int)vlen, value);
721 	return -EBADMSG;
722 invalid_time:
723 	pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
724 		 tag, (int)vlen, value);
725 	return -EBADMSG;
726 }
727 EXPORT_SYMBOL_GPL(x509_decode_time);
728 
729 int x509_note_not_before(void *context, size_t hdrlen,
730 			 unsigned char tag,
731 			 const void *value, size_t vlen)
732 {
733 	struct x509_parse_context *ctx = context;
734 	return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
735 }
736 
737 int x509_note_not_after(void *context, size_t hdrlen,
738 			unsigned char tag,
739 			const void *value, size_t vlen)
740 {
741 	struct x509_parse_context *ctx = context;
742 	return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
743 }
744 
745 /*
746  * Note a key identifier-based AuthorityKeyIdentifier
747  */
748 int x509_akid_note_kid(void *context, size_t hdrlen,
749 		       unsigned char tag,
750 		       const void *value, size_t vlen)
751 {
752 	struct x509_parse_context *ctx = context;
753 	struct asymmetric_key_id *kid;
754 
755 	pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
756 
757 	if (ctx->cert->sig->auth_ids[1])
758 		return 0;
759 
760 	kid = asymmetric_key_generate_id(value, vlen, "", 0);
761 	if (IS_ERR(kid))
762 		return PTR_ERR(kid);
763 	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
764 	ctx->cert->sig->auth_ids[1] = kid;
765 	return 0;
766 }
767 
768 /*
769  * Note a directoryName in an AuthorityKeyIdentifier
770  */
771 int x509_akid_note_name(void *context, size_t hdrlen,
772 			unsigned char tag,
773 			const void *value, size_t vlen)
774 {
775 	struct x509_parse_context *ctx = context;
776 
777 	pr_debug("AKID: name: %*phN\n", (int)vlen, value);
778 
779 	ctx->akid_raw_issuer = value;
780 	ctx->akid_raw_issuer_size = vlen;
781 	return 0;
782 }
783 
784 /*
785  * Note a serial number in an AuthorityKeyIdentifier
786  */
787 int x509_akid_note_serial(void *context, size_t hdrlen,
788 			  unsigned char tag,
789 			  const void *value, size_t vlen)
790 {
791 	struct x509_parse_context *ctx = context;
792 	struct asymmetric_key_id *kid;
793 
794 	pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
795 
796 	if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
797 		return 0;
798 
799 	kid = asymmetric_key_generate_id(value,
800 					 vlen,
801 					 ctx->akid_raw_issuer,
802 					 ctx->akid_raw_issuer_size);
803 	if (IS_ERR(kid))
804 		return PTR_ERR(kid);
805 
806 	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
807 	ctx->cert->sig->auth_ids[0] = kid;
808 	return 0;
809 }
810