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 	case OID_md2WithRSAEncryption:
199 	case OID_md3WithRSAEncryption:
200 	default:
201 		return -ENOPKG; /* Unsupported combination */
202 
203 	case OID_md4WithRSAEncryption:
204 		ctx->cert->sig->hash_algo = "md4";
205 		goto rsa_pkcs1;
206 
207 	case OID_sha1WithRSAEncryption:
208 		ctx->cert->sig->hash_algo = "sha1";
209 		goto rsa_pkcs1;
210 
211 	case OID_sha256WithRSAEncryption:
212 		ctx->cert->sig->hash_algo = "sha256";
213 		goto rsa_pkcs1;
214 
215 	case OID_sha384WithRSAEncryption:
216 		ctx->cert->sig->hash_algo = "sha384";
217 		goto rsa_pkcs1;
218 
219 	case OID_sha512WithRSAEncryption:
220 		ctx->cert->sig->hash_algo = "sha512";
221 		goto rsa_pkcs1;
222 
223 	case OID_sha224WithRSAEncryption:
224 		ctx->cert->sig->hash_algo = "sha224";
225 		goto rsa_pkcs1;
226 
227 	case OID_id_ecdsa_with_sha1:
228 		ctx->cert->sig->hash_algo = "sha1";
229 		goto ecdsa;
230 
231 	case OID_id_ecdsa_with_sha224:
232 		ctx->cert->sig->hash_algo = "sha224";
233 		goto ecdsa;
234 
235 	case OID_id_ecdsa_with_sha256:
236 		ctx->cert->sig->hash_algo = "sha256";
237 		goto ecdsa;
238 
239 	case OID_id_ecdsa_with_sha384:
240 		ctx->cert->sig->hash_algo = "sha384";
241 		goto ecdsa;
242 
243 	case OID_id_ecdsa_with_sha512:
244 		ctx->cert->sig->hash_algo = "sha512";
245 		goto ecdsa;
246 
247 	case OID_gost2012Signature256:
248 		ctx->cert->sig->hash_algo = "streebog256";
249 		goto ecrdsa;
250 
251 	case OID_gost2012Signature512:
252 		ctx->cert->sig->hash_algo = "streebog512";
253 		goto ecrdsa;
254 
255 	case OID_SM2_with_SM3:
256 		ctx->cert->sig->hash_algo = "sm3";
257 		goto sm2;
258 	}
259 
260 rsa_pkcs1:
261 	ctx->cert->sig->pkey_algo = "rsa";
262 	ctx->cert->sig->encoding = "pkcs1";
263 	ctx->sig_algo = ctx->last_oid;
264 	return 0;
265 ecrdsa:
266 	ctx->cert->sig->pkey_algo = "ecrdsa";
267 	ctx->cert->sig->encoding = "raw";
268 	ctx->sig_algo = ctx->last_oid;
269 	return 0;
270 sm2:
271 	ctx->cert->sig->pkey_algo = "sm2";
272 	ctx->cert->sig->encoding = "raw";
273 	ctx->sig_algo = ctx->last_oid;
274 	return 0;
275 ecdsa:
276 	ctx->cert->sig->pkey_algo = "ecdsa";
277 	ctx->cert->sig->encoding = "x962";
278 	ctx->sig_algo = ctx->last_oid;
279 	return 0;
280 }
281 
282 /*
283  * Note the whereabouts and type of the signature.
284  */
285 int x509_note_signature(void *context, size_t hdrlen,
286 			unsigned char tag,
287 			const void *value, size_t vlen)
288 {
289 	struct x509_parse_context *ctx = context;
290 
291 	pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
292 
293 	/*
294 	 * In X.509 certificates, the signature's algorithm is stored in two
295 	 * places: inside the TBSCertificate (the data that is signed), and
296 	 * alongside the signature.  These *must* match.
297 	 */
298 	if (ctx->last_oid != ctx->sig_algo) {
299 		pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
300 			ctx->last_oid, ctx->sig_algo);
301 		return -EINVAL;
302 	}
303 
304 	if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
305 	    strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
306 	    strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
307 	    strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
308 		/* Discard the BIT STRING metadata */
309 		if (vlen < 1 || *(const u8 *)value != 0)
310 			return -EBADMSG;
311 
312 		value++;
313 		vlen--;
314 	}
315 
316 	ctx->cert->raw_sig = value;
317 	ctx->cert->raw_sig_size = vlen;
318 	return 0;
319 }
320 
321 /*
322  * Note the certificate serial number
323  */
324 int x509_note_serial(void *context, size_t hdrlen,
325 		     unsigned char tag,
326 		     const void *value, size_t vlen)
327 {
328 	struct x509_parse_context *ctx = context;
329 	ctx->cert->raw_serial = value;
330 	ctx->cert->raw_serial_size = vlen;
331 	return 0;
332 }
333 
334 /*
335  * Note some of the name segments from which we'll fabricate a name.
336  */
337 int x509_extract_name_segment(void *context, size_t hdrlen,
338 			      unsigned char tag,
339 			      const void *value, size_t vlen)
340 {
341 	struct x509_parse_context *ctx = context;
342 
343 	switch (ctx->last_oid) {
344 	case OID_commonName:
345 		ctx->cn_size = vlen;
346 		ctx->cn_offset = (unsigned long)value - ctx->data;
347 		break;
348 	case OID_organizationName:
349 		ctx->o_size = vlen;
350 		ctx->o_offset = (unsigned long)value - ctx->data;
351 		break;
352 	case OID_email_address:
353 		ctx->email_size = vlen;
354 		ctx->email_offset = (unsigned long)value - ctx->data;
355 		break;
356 	default:
357 		break;
358 	}
359 
360 	return 0;
361 }
362 
363 /*
364  * Fabricate and save the issuer and subject names
365  */
366 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
367 			       unsigned char tag,
368 			       char **_name, size_t vlen)
369 {
370 	const void *name, *data = (const void *)ctx->data;
371 	size_t namesize;
372 	char *buffer;
373 
374 	if (*_name)
375 		return -EINVAL;
376 
377 	/* Empty name string if no material */
378 	if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
379 		buffer = kmalloc(1, GFP_KERNEL);
380 		if (!buffer)
381 			return -ENOMEM;
382 		buffer[0] = 0;
383 		goto done;
384 	}
385 
386 	if (ctx->cn_size && ctx->o_size) {
387 		/* Consider combining O and CN, but use only the CN if it is
388 		 * prefixed by the O, or a significant portion thereof.
389 		 */
390 		namesize = ctx->cn_size;
391 		name = data + ctx->cn_offset;
392 		if (ctx->cn_size >= ctx->o_size &&
393 		    memcmp(data + ctx->cn_offset, data + ctx->o_offset,
394 			   ctx->o_size) == 0)
395 			goto single_component;
396 		if (ctx->cn_size >= 7 &&
397 		    ctx->o_size >= 7 &&
398 		    memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
399 			goto single_component;
400 
401 		buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
402 				 GFP_KERNEL);
403 		if (!buffer)
404 			return -ENOMEM;
405 
406 		memcpy(buffer,
407 		       data + ctx->o_offset, ctx->o_size);
408 		buffer[ctx->o_size + 0] = ':';
409 		buffer[ctx->o_size + 1] = ' ';
410 		memcpy(buffer + ctx->o_size + 2,
411 		       data + ctx->cn_offset, ctx->cn_size);
412 		buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
413 		goto done;
414 
415 	} else if (ctx->cn_size) {
416 		namesize = ctx->cn_size;
417 		name = data + ctx->cn_offset;
418 	} else if (ctx->o_size) {
419 		namesize = ctx->o_size;
420 		name = data + ctx->o_offset;
421 	} else {
422 		namesize = ctx->email_size;
423 		name = data + ctx->email_offset;
424 	}
425 
426 single_component:
427 	buffer = kmalloc(namesize + 1, GFP_KERNEL);
428 	if (!buffer)
429 		return -ENOMEM;
430 	memcpy(buffer, name, namesize);
431 	buffer[namesize] = 0;
432 
433 done:
434 	*_name = buffer;
435 	ctx->cn_size = 0;
436 	ctx->o_size = 0;
437 	ctx->email_size = 0;
438 	return 0;
439 }
440 
441 int x509_note_issuer(void *context, size_t hdrlen,
442 		     unsigned char tag,
443 		     const void *value, size_t vlen)
444 {
445 	struct x509_parse_context *ctx = context;
446 	struct asymmetric_key_id *kid;
447 
448 	ctx->cert->raw_issuer = value;
449 	ctx->cert->raw_issuer_size = vlen;
450 
451 	if (!ctx->cert->sig->auth_ids[2]) {
452 		kid = asymmetric_key_generate_id(value, vlen, "", 0);
453 		if (IS_ERR(kid))
454 			return PTR_ERR(kid);
455 		ctx->cert->sig->auth_ids[2] = kid;
456 	}
457 
458 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
459 }
460 
461 int x509_note_subject(void *context, size_t hdrlen,
462 		      unsigned char tag,
463 		      const void *value, size_t vlen)
464 {
465 	struct x509_parse_context *ctx = context;
466 	ctx->cert->raw_subject = value;
467 	ctx->cert->raw_subject_size = vlen;
468 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
469 }
470 
471 /*
472  * Extract the parameters for the public key
473  */
474 int x509_note_params(void *context, size_t hdrlen,
475 		     unsigned char tag,
476 		     const void *value, size_t vlen)
477 {
478 	struct x509_parse_context *ctx = context;
479 
480 	/*
481 	 * AlgorithmIdentifier is used three times in the x509, we should skip
482 	 * first and ignore third, using second one which is after subject and
483 	 * before subjectPublicKey.
484 	 */
485 	if (!ctx->cert->raw_subject || ctx->key)
486 		return 0;
487 	ctx->params = value - hdrlen;
488 	ctx->params_size = vlen + hdrlen;
489 	return 0;
490 }
491 
492 /*
493  * Extract the data for the public key algorithm
494  */
495 int x509_extract_key_data(void *context, size_t hdrlen,
496 			  unsigned char tag,
497 			  const void *value, size_t vlen)
498 {
499 	struct x509_parse_context *ctx = context;
500 	enum OID oid;
501 
502 	ctx->key_algo = ctx->last_oid;
503 	switch (ctx->last_oid) {
504 	case OID_rsaEncryption:
505 		ctx->cert->pub->pkey_algo = "rsa";
506 		break;
507 	case OID_gost2012PKey256:
508 	case OID_gost2012PKey512:
509 		ctx->cert->pub->pkey_algo = "ecrdsa";
510 		break;
511 	case OID_sm2:
512 		ctx->cert->pub->pkey_algo = "sm2";
513 		break;
514 	case OID_id_ecPublicKey:
515 		if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
516 			return -EBADMSG;
517 
518 		switch (oid) {
519 		case OID_sm2:
520 			ctx->cert->pub->pkey_algo = "sm2";
521 			break;
522 		case OID_id_prime192v1:
523 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
524 			break;
525 		case OID_id_prime256v1:
526 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
527 			break;
528 		case OID_id_ansip384r1:
529 			ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
530 			break;
531 		default:
532 			return -ENOPKG;
533 		}
534 		break;
535 	default:
536 		return -ENOPKG;
537 	}
538 
539 	/* Discard the BIT STRING metadata */
540 	if (vlen < 1 || *(const u8 *)value != 0)
541 		return -EBADMSG;
542 	ctx->key = value + 1;
543 	ctx->key_size = vlen - 1;
544 	return 0;
545 }
546 
547 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
548 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
549 
550 /*
551  * Process certificate extensions that are used to qualify the certificate.
552  */
553 int x509_process_extension(void *context, size_t hdrlen,
554 			   unsigned char tag,
555 			   const void *value, size_t vlen)
556 {
557 	struct x509_parse_context *ctx = context;
558 	struct asymmetric_key_id *kid;
559 	const unsigned char *v = value;
560 
561 	pr_debug("Extension: %u\n", ctx->last_oid);
562 
563 	if (ctx->last_oid == OID_subjectKeyIdentifier) {
564 		/* Get hold of the key fingerprint */
565 		if (ctx->cert->skid || vlen < 3)
566 			return -EBADMSG;
567 		if (v[0] != ASN1_OTS || v[1] != vlen - 2)
568 			return -EBADMSG;
569 		v += 2;
570 		vlen -= 2;
571 
572 		ctx->cert->raw_skid_size = vlen;
573 		ctx->cert->raw_skid = v;
574 		kid = asymmetric_key_generate_id(v, vlen, "", 0);
575 		if (IS_ERR(kid))
576 			return PTR_ERR(kid);
577 		ctx->cert->skid = kid;
578 		pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
579 		return 0;
580 	}
581 
582 	if (ctx->last_oid == OID_keyUsage) {
583 		/*
584 		 * Get hold of the keyUsage bit string
585 		 * v[1] is the encoding size
586 		 *       (Expect either 0x02 or 0x03, making it 1 or 2 bytes)
587 		 * v[2] is the number of unused bits in the bit string
588 		 *       (If >= 3 keyCertSign is missing when v[1] = 0x02)
589 		 * v[3] and possibly v[4] contain the bit string
590 		 *
591 		 * From RFC 5280 4.2.1.3:
592 		 *   0x04 is where keyCertSign lands in this bit string
593 		 *   0x80 is where digitalSignature lands in this bit string
594 		 */
595 		if (v[0] != ASN1_BTS)
596 			return -EBADMSG;
597 		if (vlen < 4)
598 			return -EBADMSG;
599 		if (v[2] >= 8)
600 			return -EBADMSG;
601 		if (v[3] & 0x80)
602 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG;
603 		if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04))
604 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
605 		else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04))
606 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
607 		return 0;
608 	}
609 
610 	if (ctx->last_oid == OID_authorityKeyIdentifier) {
611 		/* Get hold of the CA key fingerprint */
612 		ctx->raw_akid = v;
613 		ctx->raw_akid_size = vlen;
614 		return 0;
615 	}
616 
617 	if (ctx->last_oid == OID_basicConstraints) {
618 		/*
619 		 * Get hold of the basicConstraints
620 		 * v[1] is the encoding size
621 		 *	(Expect 0x2 or greater, making it 1 or more bytes)
622 		 * v[2] is the encoding type
623 		 *	(Expect an ASN1_BOOL for the CA)
624 		 * v[3] is the contents of the ASN1_BOOL
625 		 *      (Expect 1 if the CA is TRUE)
626 		 * vlen should match the entire extension size
627 		 */
628 		if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
629 			return -EBADMSG;
630 		if (vlen < 2)
631 			return -EBADMSG;
632 		if (v[1] != vlen - 2)
633 			return -EBADMSG;
634 		if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
635 			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA;
636 		return 0;
637 	}
638 
639 	return 0;
640 }
641 
642 /**
643  * x509_decode_time - Decode an X.509 time ASN.1 object
644  * @_t: The time to fill in
645  * @hdrlen: The length of the object header
646  * @tag: The object tag
647  * @value: The object value
648  * @vlen: The size of the object value
649  *
650  * Decode an ASN.1 universal time or generalised time field into a struct the
651  * kernel can handle and check it for validity.  The time is decoded thus:
652  *
653  *	[RFC5280 §4.1.2.5]
654  *	CAs conforming to this profile MUST always encode certificate validity
655  *	dates through the year 2049 as UTCTime; certificate validity dates in
656  *	2050 or later MUST be encoded as GeneralizedTime.  Conforming
657  *	applications MUST be able to process validity dates that are encoded in
658  *	either UTCTime or GeneralizedTime.
659  */
660 int x509_decode_time(time64_t *_t,  size_t hdrlen,
661 		     unsigned char tag,
662 		     const unsigned char *value, size_t vlen)
663 {
664 	static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
665 						       31, 31, 30, 31, 30, 31 };
666 	const unsigned char *p = value;
667 	unsigned year, mon, day, hour, min, sec, mon_len;
668 
669 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
670 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
671 
672 	if (tag == ASN1_UNITIM) {
673 		/* UTCTime: YYMMDDHHMMSSZ */
674 		if (vlen != 13)
675 			goto unsupported_time;
676 		year = DD2bin(p);
677 		if (year >= 50)
678 			year += 1900;
679 		else
680 			year += 2000;
681 	} else if (tag == ASN1_GENTIM) {
682 		/* GenTime: YYYYMMDDHHMMSSZ */
683 		if (vlen != 15)
684 			goto unsupported_time;
685 		year = DD2bin(p) * 100 + DD2bin(p);
686 		if (year >= 1950 && year <= 2049)
687 			goto invalid_time;
688 	} else {
689 		goto unsupported_time;
690 	}
691 
692 	mon  = DD2bin(p);
693 	day = DD2bin(p);
694 	hour = DD2bin(p);
695 	min  = DD2bin(p);
696 	sec  = DD2bin(p);
697 
698 	if (*p != 'Z')
699 		goto unsupported_time;
700 
701 	if (year < 1970 ||
702 	    mon < 1 || mon > 12)
703 		goto invalid_time;
704 
705 	mon_len = month_lengths[mon - 1];
706 	if (mon == 2) {
707 		if (year % 4 == 0) {
708 			mon_len = 29;
709 			if (year % 100 == 0) {
710 				mon_len = 28;
711 				if (year % 400 == 0)
712 					mon_len = 29;
713 			}
714 		}
715 	}
716 
717 	if (day < 1 || day > mon_len ||
718 	    hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
719 	    min > 59 ||
720 	    sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
721 		goto invalid_time;
722 
723 	*_t = mktime64(year, mon, day, hour, min, sec);
724 	return 0;
725 
726 unsupported_time:
727 	pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
728 		 tag, (int)vlen, value);
729 	return -EBADMSG;
730 invalid_time:
731 	pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
732 		 tag, (int)vlen, value);
733 	return -EBADMSG;
734 }
735 EXPORT_SYMBOL_GPL(x509_decode_time);
736 
737 int x509_note_not_before(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_from, hdrlen, tag, value, vlen);
743 }
744 
745 int x509_note_not_after(void *context, size_t hdrlen,
746 			unsigned char tag,
747 			const void *value, size_t vlen)
748 {
749 	struct x509_parse_context *ctx = context;
750 	return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
751 }
752 
753 /*
754  * Note a key identifier-based AuthorityKeyIdentifier
755  */
756 int x509_akid_note_kid(void *context, size_t hdrlen,
757 		       unsigned char tag,
758 		       const void *value, size_t vlen)
759 {
760 	struct x509_parse_context *ctx = context;
761 	struct asymmetric_key_id *kid;
762 
763 	pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
764 
765 	if (ctx->cert->sig->auth_ids[1])
766 		return 0;
767 
768 	kid = asymmetric_key_generate_id(value, vlen, "", 0);
769 	if (IS_ERR(kid))
770 		return PTR_ERR(kid);
771 	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
772 	ctx->cert->sig->auth_ids[1] = kid;
773 	return 0;
774 }
775 
776 /*
777  * Note a directoryName in an AuthorityKeyIdentifier
778  */
779 int x509_akid_note_name(void *context, size_t hdrlen,
780 			unsigned char tag,
781 			const void *value, size_t vlen)
782 {
783 	struct x509_parse_context *ctx = context;
784 
785 	pr_debug("AKID: name: %*phN\n", (int)vlen, value);
786 
787 	ctx->akid_raw_issuer = value;
788 	ctx->akid_raw_issuer_size = vlen;
789 	return 0;
790 }
791 
792 /*
793  * Note a serial number in an AuthorityKeyIdentifier
794  */
795 int x509_akid_note_serial(void *context, size_t hdrlen,
796 			  unsigned char tag,
797 			  const void *value, size_t vlen)
798 {
799 	struct x509_parse_context *ctx = context;
800 	struct asymmetric_key_id *kid;
801 
802 	pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
803 
804 	if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
805 		return 0;
806 
807 	kid = asymmetric_key_generate_id(value,
808 					 vlen,
809 					 ctx->akid_raw_issuer,
810 					 ctx->akid_raw_issuer_size);
811 	if (IS_ERR(kid))
812 		return PTR_ERR(kid);
813 
814 	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
815 	ctx->cert->sig->auth_ids[0] = kid;
816 	return 0;
817 }
818