1 /* X.509 certificate parser
3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
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"
23 struct 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;
45 * Free an X.509 certificate
47 void x509_free_certificate(struct x509_certificate *cert)
50 public_key_free(cert->pub);
51 public_key_signature_free(cert->sig);
59 EXPORT_SYMBOL_GPL(x509_free_certificate);
62 * Parse an X.509 certificate
64 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
66 struct x509_certificate *cert;
67 struct x509_parse_context *ctx;
68 struct asymmetric_key_id *kid;
72 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
75 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
78 cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
81 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
86 ctx->data = (unsigned long)data;
88 /* Attempt to decode the certificate */
89 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
93 /* Decode the AuthorityKeyIdentifier */
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);
100 pr_warn("Couldn't decode AuthKeyIdentifier\n");
106 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
110 cert->pub->keylen = ctx->key_size;
112 /* Grab the signature bits */
113 ret = x509_get_sig_params(cert);
117 /* Generate cert issuer + serial number key ID */
118 kid = asymmetric_key_generate_id(cert->raw_serial,
119 cert->raw_serial_size,
121 cert->raw_issuer_size);
128 /* Detect self-signed certificates */
129 ret = x509_check_for_self_signed(cert);
139 x509_free_certificate(cert);
143 EXPORT_SYMBOL_GPL(x509_cert_parse);
146 * Note an OID when we find one for later processing when we know how
149 int x509_note_OID(void *context, size_t hdrlen,
151 const void *value, size_t vlen)
153 struct x509_parse_context *ctx = context;
155 ctx->last_oid = look_up_OID(value, vlen);
156 if (ctx->last_oid == OID__NR) {
158 sprint_oid(value, vlen, buffer, sizeof(buffer));
159 pr_debug("Unknown OID: [%lu] %s\n",
160 (unsigned long)value - ctx->data, buffer);
166 * Save the position of the TBS data so that we can check the signature over it
169 int x509_note_tbs_certificate(void *context, size_t hdrlen,
171 const void *value, size_t vlen)
173 struct x509_parse_context *ctx = context;
175 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
176 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
178 ctx->cert->tbs = value - hdrlen;
179 ctx->cert->tbs_size = vlen + hdrlen;
184 * Record the public key algorithm
186 int x509_note_pkey_algo(void *context, size_t hdrlen,
188 const void *value, size_t vlen)
190 struct x509_parse_context *ctx = context;
192 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
194 switch (ctx->last_oid) {
195 case OID_md2WithRSAEncryption:
196 case OID_md3WithRSAEncryption:
198 return -ENOPKG; /* Unsupported combination */
200 case OID_md4WithRSAEncryption:
201 ctx->cert->sig->hash_algo = "md4";
202 ctx->cert->sig->pkey_algo = "rsa";
205 case OID_sha1WithRSAEncryption:
206 ctx->cert->sig->hash_algo = "sha1";
207 ctx->cert->sig->pkey_algo = "rsa";
210 case OID_sha256WithRSAEncryption:
211 ctx->cert->sig->hash_algo = "sha256";
212 ctx->cert->sig->pkey_algo = "rsa";
215 case OID_sha384WithRSAEncryption:
216 ctx->cert->sig->hash_algo = "sha384";
217 ctx->cert->sig->pkey_algo = "rsa";
220 case OID_sha512WithRSAEncryption:
221 ctx->cert->sig->hash_algo = "sha512";
222 ctx->cert->sig->pkey_algo = "rsa";
225 case OID_sha224WithRSAEncryption:
226 ctx->cert->sig->hash_algo = "sha224";
227 ctx->cert->sig->pkey_algo = "rsa";
231 ctx->algo_oid = ctx->last_oid;
236 * Note the whereabouts and type of the signature.
238 int x509_note_signature(void *context, size_t hdrlen,
240 const void *value, size_t vlen)
242 struct x509_parse_context *ctx = context;
244 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
246 if (ctx->last_oid != ctx->algo_oid) {
247 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
248 ctx->algo_oid, ctx->last_oid);
252 if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0) {
253 /* Discard the BIT STRING metadata */
254 if (vlen < 1 || *(const u8 *)value != 0)
261 ctx->cert->raw_sig = value;
262 ctx->cert->raw_sig_size = vlen;
267 * Note the certificate serial number
269 int x509_note_serial(void *context, size_t hdrlen,
271 const void *value, size_t vlen)
273 struct x509_parse_context *ctx = context;
274 ctx->cert->raw_serial = value;
275 ctx->cert->raw_serial_size = vlen;
280 * Note some of the name segments from which we'll fabricate a name.
282 int x509_extract_name_segment(void *context, size_t hdrlen,
284 const void *value, size_t vlen)
286 struct x509_parse_context *ctx = context;
288 switch (ctx->last_oid) {
291 ctx->cn_offset = (unsigned long)value - ctx->data;
293 case OID_organizationName:
295 ctx->o_offset = (unsigned long)value - ctx->data;
297 case OID_email_address:
298 ctx->email_size = vlen;
299 ctx->email_offset = (unsigned long)value - ctx->data;
309 * Fabricate and save the issuer and subject names
311 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
313 char **_name, size_t vlen)
315 const void *name, *data = (const void *)ctx->data;
322 /* Empty name string if no material */
323 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
324 buffer = kmalloc(1, GFP_KERNEL);
331 if (ctx->cn_size && ctx->o_size) {
332 /* Consider combining O and CN, but use only the CN if it is
333 * prefixed by the O, or a significant portion thereof.
335 namesize = ctx->cn_size;
336 name = data + ctx->cn_offset;
337 if (ctx->cn_size >= ctx->o_size &&
338 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
340 goto single_component;
341 if (ctx->cn_size >= 7 &&
343 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
344 goto single_component;
346 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
352 data + ctx->o_offset, ctx->o_size);
353 buffer[ctx->o_size + 0] = ':';
354 buffer[ctx->o_size + 1] = ' ';
355 memcpy(buffer + ctx->o_size + 2,
356 data + ctx->cn_offset, ctx->cn_size);
357 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
360 } else if (ctx->cn_size) {
361 namesize = ctx->cn_size;
362 name = data + ctx->cn_offset;
363 } else if (ctx->o_size) {
364 namesize = ctx->o_size;
365 name = data + ctx->o_offset;
367 namesize = ctx->email_size;
368 name = data + ctx->email_offset;
372 buffer = kmalloc(namesize + 1, GFP_KERNEL);
375 memcpy(buffer, name, namesize);
376 buffer[namesize] = 0;
386 int x509_note_issuer(void *context, size_t hdrlen,
388 const void *value, size_t vlen)
390 struct x509_parse_context *ctx = context;
391 ctx->cert->raw_issuer = value;
392 ctx->cert->raw_issuer_size = vlen;
393 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
396 int x509_note_subject(void *context, size_t hdrlen,
398 const void *value, size_t vlen)
400 struct x509_parse_context *ctx = context;
401 ctx->cert->raw_subject = value;
402 ctx->cert->raw_subject_size = vlen;
403 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
407 * Extract the data for the public key algorithm
409 int x509_extract_key_data(void *context, size_t hdrlen,
411 const void *value, size_t vlen)
413 struct x509_parse_context *ctx = context;
415 if (ctx->last_oid != OID_rsaEncryption)
418 ctx->cert->pub->pkey_algo = "rsa";
420 /* Discard the BIT STRING metadata */
421 if (vlen < 1 || *(const u8 *)value != 0)
423 ctx->key = value + 1;
424 ctx->key_size = vlen - 1;
428 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
429 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
432 * Process certificate extensions that are used to qualify the certificate.
434 int x509_process_extension(void *context, size_t hdrlen,
436 const void *value, size_t vlen)
438 struct x509_parse_context *ctx = context;
439 struct asymmetric_key_id *kid;
440 const unsigned char *v = value;
442 pr_debug("Extension: %u\n", ctx->last_oid);
444 if (ctx->last_oid == OID_subjectKeyIdentifier) {
445 /* Get hold of the key fingerprint */
446 if (ctx->cert->skid || vlen < 3)
448 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
453 ctx->cert->raw_skid_size = vlen;
454 ctx->cert->raw_skid = v;
455 kid = asymmetric_key_generate_id(v, vlen, "", 0);
458 ctx->cert->skid = kid;
459 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
463 if (ctx->last_oid == OID_authorityKeyIdentifier) {
464 /* Get hold of the CA key fingerprint */
466 ctx->raw_akid_size = vlen;
474 * x509_decode_time - Decode an X.509 time ASN.1 object
475 * @_t: The time to fill in
476 * @hdrlen: The length of the object header
477 * @tag: The object tag
478 * @value: The object value
479 * @vlen: The size of the object value
481 * Decode an ASN.1 universal time or generalised time field into a struct the
482 * kernel can handle and check it for validity. The time is decoded thus:
484 * [RFC5280 ยง4.1.2.5]
485 * CAs conforming to this profile MUST always encode certificate validity
486 * dates through the year 2049 as UTCTime; certificate validity dates in
487 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
488 * applications MUST be able to process validity dates that are encoded in
489 * either UTCTime or GeneralizedTime.
491 int x509_decode_time(time64_t *_t, size_t hdrlen,
493 const unsigned char *value, size_t vlen)
495 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
496 31, 31, 30, 31, 30, 31 };
497 const unsigned char *p = value;
498 unsigned year, mon, day, hour, min, sec, mon_len;
500 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
501 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
503 if (tag == ASN1_UNITIM) {
504 /* UTCTime: YYMMDDHHMMSSZ */
506 goto unsupported_time;
512 } else if (tag == ASN1_GENTIM) {
513 /* GenTime: YYYYMMDDHHMMSSZ */
515 goto unsupported_time;
516 year = DD2bin(p) * 100 + DD2bin(p);
517 if (year >= 1950 && year <= 2049)
520 goto unsupported_time;
530 goto unsupported_time;
536 mon_len = month_lengths[mon - 1];
540 if (year % 100 == 0) {
548 if (day < 1 || day > mon_len ||
549 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
551 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
554 *_t = mktime64(year, mon, day, hour, min, sec);
558 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
559 tag, (int)vlen, value);
562 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
563 tag, (int)vlen, value);
566 EXPORT_SYMBOL_GPL(x509_decode_time);
568 int x509_note_not_before(void *context, size_t hdrlen,
570 const void *value, size_t vlen)
572 struct x509_parse_context *ctx = context;
573 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
576 int x509_note_not_after(void *context, size_t hdrlen,
578 const void *value, size_t vlen)
580 struct x509_parse_context *ctx = context;
581 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
585 * Note a key identifier-based AuthorityKeyIdentifier
587 int x509_akid_note_kid(void *context, size_t hdrlen,
589 const void *value, size_t vlen)
591 struct x509_parse_context *ctx = context;
592 struct asymmetric_key_id *kid;
594 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
596 if (ctx->cert->sig->auth_ids[1])
599 kid = asymmetric_key_generate_id(value, vlen, "", 0);
602 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
603 ctx->cert->sig->auth_ids[1] = kid;
608 * Note a directoryName in an AuthorityKeyIdentifier
610 int x509_akid_note_name(void *context, size_t hdrlen,
612 const void *value, size_t vlen)
614 struct x509_parse_context *ctx = context;
616 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
618 ctx->akid_raw_issuer = value;
619 ctx->akid_raw_issuer_size = vlen;
624 * Note a serial number in an AuthorityKeyIdentifier
626 int x509_akid_note_serial(void *context, size_t hdrlen,
628 const void *value, size_t vlen)
630 struct x509_parse_context *ctx = context;
631 struct asymmetric_key_id *kid;
633 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
635 if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
638 kid = asymmetric_key_generate_id(value,
640 ctx->akid_raw_issuer,
641 ctx->akid_raw_issuer_size);
645 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
646 ctx->cert->sig->auth_ids[0] = kid;