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 "public_key.h"
19 #include "x509_parser.h"
20 #include "x509-asn1.h"
21 #include "x509_akid-asn1.h"
22 #include "x509_rsakey-asn1.h"
24 struct x509_parse_context {
25 struct x509_certificate *cert; /* Certificate being constructed */
26 unsigned long data; /* Start of data */
27 const void *cert_start; /* Start of cert content */
28 const void *key; /* Key data */
29 size_t key_size; /* Size of key data */
30 enum OID last_oid; /* Last OID encountered */
31 enum OID algo_oid; /* Algorithm OID */
32 unsigned char nr_mpi; /* Number of MPIs stored */
33 u8 o_size; /* Size of organizationName (O) */
34 u8 cn_size; /* Size of commonName (CN) */
35 u8 email_size; /* Size of emailAddress */
36 u16 o_offset; /* Offset of organizationName (O) */
37 u16 cn_offset; /* Offset of commonName (CN) */
38 u16 email_offset; /* Offset of emailAddress */
39 unsigned raw_akid_size;
40 const void *raw_akid; /* Raw authorityKeyId in ASN.1 */
41 const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */
42 unsigned akid_raw_issuer_size;
46 * Free an X.509 certificate
48 void x509_free_certificate(struct x509_certificate *cert)
51 public_key_destroy(cert->pub);
57 kfree(cert->akid_skid);
58 kfree(cert->sig.digest);
59 mpi_free(cert->sig.rsa.s);
63 EXPORT_SYMBOL_GPL(x509_free_certificate);
66 * Parse an X.509 certificate
68 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
70 struct x509_certificate *cert;
71 struct x509_parse_context *ctx;
72 struct asymmetric_key_id *kid;
76 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
79 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
82 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
87 ctx->data = (unsigned long)data;
89 /* Attempt to decode the certificate */
90 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
94 /* Decode the AuthorityKeyIdentifier */
96 pr_devel("AKID: %u %*phN\n",
97 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
98 ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
99 ctx->raw_akid, ctx->raw_akid_size);
101 pr_warn("Couldn't decode AuthKeyIdentifier\n");
106 /* Decode the public key */
107 ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
108 ctx->key, ctx->key_size);
112 /* Generate cert issuer + serial number key ID */
113 kid = asymmetric_key_generate_id(cert->raw_serial,
114 cert->raw_serial_size,
116 cert->raw_issuer_size);
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.pkey_hash_algo = HASH_ALGO_MD5;
192 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
195 case OID_sha1WithRSAEncryption:
196 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1;
197 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
200 case OID_sha256WithRSAEncryption:
201 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256;
202 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
205 case OID_sha384WithRSAEncryption:
206 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384;
207 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
210 case OID_sha512WithRSAEncryption:
211 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512;
212 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
215 case OID_sha224WithRSAEncryption:
216 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224;
217 ctx->cert->sig.pkey_algo = 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 = PKEY_ALGO_RSA;
401 /* Discard the BIT STRING metadata */
402 ctx->key = value + 1;
403 ctx->key_size = vlen - 1;
408 * Extract a RSA public key value
410 int rsa_extract_mpi(void *context, size_t hdrlen,
412 const void *value, size_t vlen)
414 struct x509_parse_context *ctx = context;
417 if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
418 pr_err("Too many public key MPIs in certificate\n");
422 mpi = mpi_read_raw_data(value, vlen);
426 ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
430 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
431 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
434 * Process certificate extensions that are used to qualify the certificate.
436 int x509_process_extension(void *context, size_t hdrlen,
438 const void *value, size_t vlen)
440 struct x509_parse_context *ctx = context;
441 struct asymmetric_key_id *kid;
442 const unsigned char *v = value;
444 pr_debug("Extension: %u\n", ctx->last_oid);
446 if (ctx->last_oid == OID_subjectKeyIdentifier) {
447 /* Get hold of the key fingerprint */
448 if (ctx->cert->skid || vlen < 3)
450 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
455 ctx->cert->raw_skid_size = vlen;
456 ctx->cert->raw_skid = v;
457 kid = asymmetric_key_generate_id(v, vlen, "", 0);
460 ctx->cert->skid = kid;
461 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
465 if (ctx->last_oid == OID_authorityKeyIdentifier) {
466 /* Get hold of the CA key fingerprint */
468 ctx->raw_akid_size = vlen;
476 * x509_decode_time - Decode an X.509 time ASN.1 object
477 * @_t: The time to fill in
478 * @hdrlen: The length of the object header
479 * @tag: The object tag
480 * @value: The object value
481 * @vlen: The size of the object value
483 * Decode an ASN.1 universal time or generalised time field into a struct the
484 * kernel can handle and check it for validity. The time is decoded thus:
486 * [RFC5280 ยง4.1.2.5]
487 * CAs conforming to this profile MUST always encode certificate validity
488 * dates through the year 2049 as UTCTime; certificate validity dates in
489 * 2050 or later MUST be encoded as GeneralizedTime. Conforming
490 * applications MUST be able to process validity dates that are encoded in
491 * either UTCTime or GeneralizedTime.
493 int x509_decode_time(time64_t *_t, size_t hdrlen,
495 const unsigned char *value, size_t vlen)
497 static const unsigned char month_lengths[] = { 31, 29, 31, 30, 31, 30,
498 31, 31, 30, 31, 30, 31 };
499 const unsigned char *p = value;
500 unsigned year, mon, day, hour, min, sec, mon_len;
502 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
503 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
505 if (tag == ASN1_UNITIM) {
506 /* UTCTime: YYMMDDHHMMSSZ */
508 goto unsupported_time;
514 } else if (tag == ASN1_GENTIM) {
515 /* GenTime: YYYYMMDDHHMMSSZ */
517 goto unsupported_time;
518 year = DD2bin(p) * 100 + DD2bin(p);
519 if (year >= 1950 && year <= 2049)
522 goto unsupported_time;
532 goto unsupported_time;
538 mon_len = month_lengths[mon - 1];
542 if (year % 100 == 0) {
550 if (day < 1 || day > mon_len ||
556 *_t = mktime64(year, mon, day, hour, min, sec);
560 pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
561 tag, (int)vlen, value);
564 pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
565 tag, (int)vlen, value);
568 EXPORT_SYMBOL_GPL(x509_decode_time);
570 int x509_note_not_before(void *context, size_t hdrlen,
572 const void *value, size_t vlen)
574 struct x509_parse_context *ctx = context;
575 return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
578 int x509_note_not_after(void *context, size_t hdrlen,
580 const void *value, size_t vlen)
582 struct x509_parse_context *ctx = context;
583 return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
587 * Note a key identifier-based AuthorityKeyIdentifier
589 int x509_akid_note_kid(void *context, size_t hdrlen,
591 const void *value, size_t vlen)
593 struct x509_parse_context *ctx = context;
594 struct asymmetric_key_id *kid;
596 pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
598 if (ctx->cert->akid_skid)
601 kid = asymmetric_key_generate_id(value, vlen, "", 0);
604 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
605 ctx->cert->akid_skid = kid;
610 * Note a directoryName in an AuthorityKeyIdentifier
612 int x509_akid_note_name(void *context, size_t hdrlen,
614 const void *value, size_t vlen)
616 struct x509_parse_context *ctx = context;
618 pr_debug("AKID: name: %*phN\n", (int)vlen, value);
620 ctx->akid_raw_issuer = value;
621 ctx->akid_raw_issuer_size = vlen;
626 * Note a serial number in an AuthorityKeyIdentifier
628 int x509_akid_note_serial(void *context, size_t hdrlen,
630 const void *value, size_t vlen)
632 struct x509_parse_context *ctx = context;
633 struct asymmetric_key_id *kid;
635 pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
637 if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
640 kid = asymmetric_key_generate_id(value,
642 ctx->akid_raw_issuer,
643 ctx->akid_raw_issuer_size);
647 pr_debug("authkeyid %*phN\n", kid->len, kid->data);
648 ctx->cert->akid_id = kid;