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_destroy(cert->pub);
56 kfree(cert->akid_skid);
57 kfree(cert->sig.digest);
62 EXPORT_SYMBOL_GPL(x509_free_certificate);
65 * Parse an X.509 certificate
67 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
69 struct x509_certificate *cert;
70 struct x509_parse_context *ctx;
71 struct asymmetric_key_id *kid;
75 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
78 cert->pub = kzalloc(sizeof(struct public_key), 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");
105 cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
109 cert->pub->keylen = ctx->key_size;
111 /* Generate cert issuer + serial number key ID */
112 kid = asymmetric_key_generate_id(cert->raw_serial,
113 cert->raw_serial_size,
115 cert->raw_issuer_size);
126 kfree(cert->pub->key);
129 x509_free_certificate(cert);
133 EXPORT_SYMBOL_GPL(x509_cert_parse);
136 * Note an OID when we find one for later processing when we know how
139 int x509_note_OID(void *context, size_t hdrlen,
141 const void *value, size_t vlen)
143 struct x509_parse_context *ctx = context;
145 ctx->last_oid = look_up_OID(value, vlen);
146 if (ctx->last_oid == OID__NR) {
148 sprint_oid(value, vlen, buffer, sizeof(buffer));
149 pr_debug("Unknown OID: [%lu] %s\n",
150 (unsigned long)value - ctx->data, buffer);
156 * Save the position of the TBS data so that we can check the signature over it
159 int x509_note_tbs_certificate(void *context, size_t hdrlen,
161 const void *value, size_t vlen)
163 struct x509_parse_context *ctx = context;
165 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
166 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
168 ctx->cert->tbs = value - hdrlen;
169 ctx->cert->tbs_size = vlen + hdrlen;
174 * Record the public key algorithm
176 int x509_note_pkey_algo(void *context, size_t hdrlen,
178 const void *value, size_t vlen)
180 struct x509_parse_context *ctx = context;
182 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
184 switch (ctx->last_oid) {
185 case OID_md2WithRSAEncryption:
186 case OID_md3WithRSAEncryption:
188 return -ENOPKG; /* Unsupported combination */
190 case OID_md4WithRSAEncryption:
191 ctx->cert->sig.hash_algo = "md4";
192 ctx->cert->sig.pkey_algo = "rsa";
195 case OID_sha1WithRSAEncryption:
196 ctx->cert->sig.hash_algo = "sha1";
197 ctx->cert->sig.pkey_algo = "rsa";
200 case OID_sha256WithRSAEncryption:
201 ctx->cert->sig.hash_algo = "sha256";
202 ctx->cert->sig.pkey_algo = "rsa";
205 case OID_sha384WithRSAEncryption:
206 ctx->cert->sig.hash_algo = "sha384";
207 ctx->cert->sig.pkey_algo = "rsa";
210 case OID_sha512WithRSAEncryption:
211 ctx->cert->sig.hash_algo = "sha512";
212 ctx->cert->sig.pkey_algo = "rsa";
215 case OID_sha224WithRSAEncryption:
216 ctx->cert->sig.hash_algo = "sha224";
217 ctx->cert->sig.pkey_algo = "rsa";
221 ctx->algo_oid = ctx->last_oid;
226 * Note the whereabouts and type of the signature.
228 int x509_note_signature(void *context, size_t hdrlen,
230 const void *value, size_t vlen)
232 struct x509_parse_context *ctx = context;
234 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
236 if (ctx->last_oid != ctx->algo_oid) {
237 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
238 ctx->algo_oid, ctx->last_oid);
242 ctx->cert->raw_sig = value;
243 ctx->cert->raw_sig_size = vlen;
248 * Note the certificate serial number
250 int x509_note_serial(void *context, size_t hdrlen,
252 const void *value, size_t vlen)
254 struct x509_parse_context *ctx = context;
255 ctx->cert->raw_serial = value;
256 ctx->cert->raw_serial_size = vlen;
261 * Note some of the name segments from which we'll fabricate a name.
263 int x509_extract_name_segment(void *context, size_t hdrlen,
265 const void *value, size_t vlen)
267 struct x509_parse_context *ctx = context;
269 switch (ctx->last_oid) {
272 ctx->cn_offset = (unsigned long)value - ctx->data;
274 case OID_organizationName:
276 ctx->o_offset = (unsigned long)value - ctx->data;
278 case OID_email_address:
279 ctx->email_size = vlen;
280 ctx->email_offset = (unsigned long)value - ctx->data;
290 * Fabricate and save the issuer and subject names
292 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
294 char **_name, size_t vlen)
296 const void *name, *data = (const void *)ctx->data;
303 /* Empty name string if no material */
304 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
305 buffer = kmalloc(1, GFP_KERNEL);
312 if (ctx->cn_size && ctx->o_size) {
313 /* Consider combining O and CN, but use only the CN if it is
314 * prefixed by the O, or a significant portion thereof.
316 namesize = ctx->cn_size;
317 name = data + ctx->cn_offset;
318 if (ctx->cn_size >= ctx->o_size &&
319 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
321 goto single_component;
322 if (ctx->cn_size >= 7 &&
324 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
325 goto single_component;
327 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
333 data + ctx->o_offset, ctx->o_size);
334 buffer[ctx->o_size + 0] = ':';
335 buffer[ctx->o_size + 1] = ' ';
336 memcpy(buffer + ctx->o_size + 2,
337 data + ctx->cn_offset, ctx->cn_size);
338 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
341 } else if (ctx->cn_size) {
342 namesize = ctx->cn_size;
343 name = data + ctx->cn_offset;
344 } else if (ctx->o_size) {
345 namesize = ctx->o_size;
346 name = data + ctx->o_offset;
348 namesize = ctx->email_size;
349 name = data + ctx->email_offset;
353 buffer = kmalloc(namesize + 1, GFP_KERNEL);
356 memcpy(buffer, name, namesize);
357 buffer[namesize] = 0;
367 int x509_note_issuer(void *context, size_t hdrlen,
369 const void *value, size_t vlen)
371 struct x509_parse_context *ctx = context;
372 ctx->cert->raw_issuer = value;
373 ctx->cert->raw_issuer_size = vlen;
374 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
377 int x509_note_subject(void *context, size_t hdrlen,
379 const void *value, size_t vlen)
381 struct x509_parse_context *ctx = context;
382 ctx->cert->raw_subject = value;
383 ctx->cert->raw_subject_size = vlen;
384 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
388 * Extract the data for the public key algorithm
390 int x509_extract_key_data(void *context, size_t hdrlen,
392 const void *value, size_t vlen)
394 struct x509_parse_context *ctx = context;
396 if (ctx->last_oid != OID_rsaEncryption)
399 ctx->cert->pub->pkey_algo = "rsa";
401 /* Discard the BIT STRING metadata */
402 ctx->key = value + 1;
403 ctx->key_size = vlen - 1;
407 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
408 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
411 * Process certificate extensions that are used to qualify the certificate.
413 int x509_process_extension(void *context, size_t hdrlen,
415 const void *value, size_t vlen)
417 struct x509_parse_context *ctx = context;
418 struct asymmetric_key_id *kid;
419 const unsigned char *v = value;
421 pr_debug("Extension: %u\n", ctx->last_oid);
423 if (ctx->last_oid == OID_subjectKeyIdentifier) {
424 /* Get hold of the key fingerprint */
425 if (ctx->cert->skid || vlen < 3)
427 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
432 ctx->cert->raw_skid_size = vlen;
433 ctx->cert->raw_skid = v;
434 kid = asymmetric_key_generate_id(v, vlen, "", 0);
437 ctx->cert->skid = kid;
438 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
442 if (ctx->last_oid == OID_authorityKeyIdentifier) {
443 /* Get hold of the CA key fingerprint */
445 ctx->raw_akid_size = vlen;
453 * x509_decode_time - Decode an X.509 time ASN.1 object
454 * @_t: The time to fill in
455 * @hdrlen: The length of the object header
456 * @tag: The object tag
457 * @value: The object value
458 * @vlen: The size of the object value
460 * Decode an ASN.1 universal time or generalised time field into a struct the
461 * kernel can handle and check it for validity. The time is decoded thus:
463 * [RFC5280 ยง4.1.2.5]
464 * CAs conforming to this profile MUST always encode certificate validity
465 * dates through the year 2049 as UTCTime; certificate validity dates in
466 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
467 * applications MUST be able to process validity dates that are encoded in
468 * either UTCTime or GeneralizedTime.
470 int x509_decode_time(time64_t *_t, size_t hdrlen,
472 const unsigned char *value, size_t vlen)
474 static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
475 31, 31, 30, 31, 30, 31 };
476 const unsigned char *p = value;
477 unsigned year, mon, day, hour, min, sec, mon_len;
479 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
480 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
482 if (tag == ASN1_UNITIM) {
483 /* UTCTime: YYMMDDHHMMSSZ */
485 goto unsupported_time;
491 } else if (tag == ASN1_GENTIM) {
492 /* GenTime: YYYYMMDDHHMMSSZ */
494 goto unsupported_time;
495 year = DD2bin(p) * 100 + DD2bin(p);
496 if (year >= 1950 && year <= 2049)
499 goto unsupported_time;
509 goto unsupported_time;
515 mon_len = month_lengths[mon - 1];
519 if (year % 100 == 0) {
527 if (day < 1 || day > mon_len ||
528 hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
530 sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
533 *_t = mktime64(year, mon, day, hour, min, sec);
537 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
538 tag, (int)vlen, value);
541 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
542 tag, (int)vlen, value);
545 EXPORT_SYMBOL_GPL(x509_decode_time);
547 int x509_note_not_before(void *context, size_t hdrlen,
549 const void *value, size_t vlen)
551 struct x509_parse_context *ctx = context;
552 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
555 int x509_note_not_after(void *context, size_t hdrlen,
557 const void *value, size_t vlen)
559 struct x509_parse_context *ctx = context;
560 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
564 * Note a key identifier-based AuthorityKeyIdentifier
566 int x509_akid_note_kid(void *context, size_t hdrlen,
568 const void *value, size_t vlen)
570 struct x509_parse_context *ctx = context;
571 struct asymmetric_key_id *kid;
573 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
575 if (ctx->cert->akid_skid)
578 kid = asymmetric_key_generate_id(value, vlen, "", 0);
581 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
582 ctx->cert->akid_skid = kid;
587 * Note a directoryName in an AuthorityKeyIdentifier
589 int x509_akid_note_name(void *context, size_t hdrlen,
591 const void *value, size_t vlen)
593 struct x509_parse_context *ctx = context;
595 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
597 ctx->akid_raw_issuer = value;
598 ctx->akid_raw_issuer_size = vlen;
603 * Note a serial number in an AuthorityKeyIdentifier
605 int x509_akid_note_serial(void *context, size_t hdrlen,
607 const void *value, size_t vlen)
609 struct x509_parse_context *ctx = context;
610 struct asymmetric_key_id *kid;
612 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
614 if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
617 kid = asymmetric_key_generate_id(value,
619 ctx->akid_raw_issuer,
620 ctx->akid_raw_issuer_size);
624 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
625 ctx->cert->akid_id = kid;