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/slab.h>
15 #include <linux/err.h>
16 #include <linux/oid_registry.h>
17 #include "public_key.h"
18 #include "x509_parser.h"
19 #include "x509-asn1.h"
20 #include "x509_rsakey-asn1.h"
22 struct x509_parse_context {
23 struct x509_certificate *cert; /* Certificate being constructed */
24 unsigned long data; /* Start of data */
25 const void *cert_start; /* Start of cert content */
26 const void *key; /* Key data */
27 size_t key_size; /* Size of key data */
28 enum OID last_oid; /* Last OID encountered */
29 enum OID algo_oid; /* Algorithm OID */
30 unsigned char nr_mpi; /* Number of MPIs stored */
31 u8 o_size; /* Size of organizationName (O) */
32 u8 cn_size; /* Size of commonName (CN) */
33 u8 email_size; /* Size of emailAddress */
34 u16 o_offset; /* Offset of organizationName (O) */
35 u16 cn_offset; /* Offset of commonName (CN) */
36 u16 email_offset; /* Offset of emailAddress */
40 * Free an X.509 certificate
42 void x509_free_certificate(struct x509_certificate *cert)
45 public_key_destroy(cert->pub);
48 kfree(cert->fingerprint);
49 kfree(cert->authority);
50 kfree(cert->sig.digest);
51 mpi_free(cert->sig.rsa.s);
57 * Parse an X.509 certificate
59 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
61 struct x509_certificate *cert;
62 struct x509_parse_context *ctx;
66 cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
69 cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
72 ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
77 ctx->data = (unsigned long)data;
79 /* Attempt to decode the certificate */
80 ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
84 /* Decode the public key */
85 ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
86 ctx->key, ctx->key_size);
96 x509_free_certificate(cert);
102 * Note an OID when we find one for later processing when we know how
105 int x509_note_OID(void *context, size_t hdrlen,
107 const void *value, size_t vlen)
109 struct x509_parse_context *ctx = context;
111 ctx->last_oid = look_up_OID(value, vlen);
112 if (ctx->last_oid == OID__NR) {
114 sprint_oid(value, vlen, buffer, sizeof(buffer));
115 pr_debug("Unknown OID: [%lu] %s\n",
116 (unsigned long)value - ctx->data, buffer);
122 * Save the position of the TBS data so that we can check the signature over it
125 int x509_note_tbs_certificate(void *context, size_t hdrlen,
127 const void *value, size_t vlen)
129 struct x509_parse_context *ctx = context;
131 pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
132 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
134 ctx->cert->tbs = value - hdrlen;
135 ctx->cert->tbs_size = vlen + hdrlen;
140 * Record the public key algorithm
142 int x509_note_pkey_algo(void *context, size_t hdrlen,
144 const void *value, size_t vlen)
146 struct x509_parse_context *ctx = context;
148 pr_debug("PubKey Algo: %u\n", ctx->last_oid);
150 switch (ctx->last_oid) {
151 case OID_md2WithRSAEncryption:
152 case OID_md3WithRSAEncryption:
154 return -ENOPKG; /* Unsupported combination */
156 case OID_md4WithRSAEncryption:
157 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_MD5;
158 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
161 case OID_sha1WithRSAEncryption:
162 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1;
163 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
166 case OID_sha256WithRSAEncryption:
167 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256;
168 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
171 case OID_sha384WithRSAEncryption:
172 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384;
173 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
176 case OID_sha512WithRSAEncryption:
177 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512;
178 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
181 case OID_sha224WithRSAEncryption:
182 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224;
183 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
187 ctx->algo_oid = ctx->last_oid;
192 * Note the whereabouts and type of the signature.
194 int x509_note_signature(void *context, size_t hdrlen,
196 const void *value, size_t vlen)
198 struct x509_parse_context *ctx = context;
200 pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
202 if (ctx->last_oid != ctx->algo_oid) {
203 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
204 ctx->algo_oid, ctx->last_oid);
208 ctx->cert->raw_sig = value;
209 ctx->cert->raw_sig_size = vlen;
214 * Note some of the name segments from which we'll fabricate a name.
216 int x509_extract_name_segment(void *context, size_t hdrlen,
218 const void *value, size_t vlen)
220 struct x509_parse_context *ctx = context;
222 switch (ctx->last_oid) {
225 ctx->cn_offset = (unsigned long)value - ctx->data;
227 case OID_organizationName:
229 ctx->o_offset = (unsigned long)value - ctx->data;
231 case OID_email_address:
232 ctx->email_size = vlen;
233 ctx->email_offset = (unsigned long)value - ctx->data;
243 * Fabricate and save the issuer and subject names
245 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
247 char **_name, size_t vlen)
249 const void *name, *data = (const void *)ctx->data;
256 /* Empty name string if no material */
257 if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
258 buffer = kmalloc(1, GFP_KERNEL);
265 if (ctx->cn_size && ctx->o_size) {
266 /* Consider combining O and CN, but use only the CN if it is
267 * prefixed by the O, or a significant portion thereof.
269 namesize = ctx->cn_size;
270 name = data + ctx->cn_offset;
271 if (ctx->cn_size >= ctx->o_size &&
272 memcmp(data + ctx->cn_offset, data + ctx->o_offset,
274 goto single_component;
275 if (ctx->cn_size >= 7 &&
277 memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
278 goto single_component;
280 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
286 data + ctx->o_offset, ctx->o_size);
287 buffer[ctx->o_size + 0] = ':';
288 buffer[ctx->o_size + 1] = ' ';
289 memcpy(buffer + ctx->o_size + 2,
290 data + ctx->cn_offset, ctx->cn_size);
291 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
294 } else if (ctx->cn_size) {
295 namesize = ctx->cn_size;
296 name = data + ctx->cn_offset;
297 } else if (ctx->o_size) {
298 namesize = ctx->o_size;
299 name = data + ctx->o_offset;
301 namesize = ctx->email_size;
302 name = data + ctx->email_offset;
306 buffer = kmalloc(namesize + 1, GFP_KERNEL);
309 memcpy(buffer, name, namesize);
310 buffer[namesize] = 0;
320 int x509_note_issuer(void *context, size_t hdrlen,
322 const void *value, size_t vlen)
324 struct x509_parse_context *ctx = context;
325 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
328 int x509_note_subject(void *context, size_t hdrlen,
330 const void *value, size_t vlen)
332 struct x509_parse_context *ctx = context;
333 return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
337 * Extract the data for the public key algorithm
339 int x509_extract_key_data(void *context, size_t hdrlen,
341 const void *value, size_t vlen)
343 struct x509_parse_context *ctx = context;
345 if (ctx->last_oid != OID_rsaEncryption)
348 ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
350 /* Discard the BIT STRING metadata */
351 ctx->key = value + 1;
352 ctx->key_size = vlen - 1;
357 * Extract a RSA public key value
359 int rsa_extract_mpi(void *context, size_t hdrlen,
361 const void *value, size_t vlen)
363 struct x509_parse_context *ctx = context;
366 if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
367 pr_err("Too many public key MPIs in certificate\n");
371 mpi = mpi_read_raw_data(value, vlen);
375 ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
379 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
380 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
383 * Process certificate extensions that are used to qualify the certificate.
385 int x509_process_extension(void *context, size_t hdrlen,
387 const void *value, size_t vlen)
389 struct x509_parse_context *ctx = context;
390 const unsigned char *v = value;
394 pr_debug("Extension: %u\n", ctx->last_oid);
396 if (ctx->last_oid == OID_subjectKeyIdentifier) {
397 /* Get hold of the key fingerprint */
400 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
405 f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
408 for (i = 0; i < vlen; i++)
409 sprintf(f + i * 2, "%02x", v[i]);
410 pr_debug("fingerprint %s\n", f);
411 ctx->cert->fingerprint = f;
415 if (ctx->last_oid == OID_authorityKeyIdentifier) {
418 /* Get hold of the CA key fingerprint */
422 /* Authority Key Identifier must be a Constructed SEQUENCE */
423 if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
426 /* Authority Key Identifier is not indefinite length */
427 if (unlikely(vlen == ASN1_INDEFINITE_LENGTH))
430 if (vlen < ASN1_INDEFINITE_LENGTH) {
431 /* Short Form length */
432 if (v[1] != vlen - 2 ||
433 v[2] != SEQ_TAG_KEYID ||
440 /* Long Form length */
442 size_t sub = v[1] - ASN1_INDEFINITE_LENGTH;
447 /* calculate the length from subsequent octets */
449 for (i = 0; i < sub; i++) {
454 if (seq_len != vlen - 2 - sub ||
455 v[sub] != SEQ_TAG_KEYID ||
456 v[sub + 1] > vlen - 4 - sub)
459 key_len = v[sub + 1];
463 f = kmalloc(key_len * 2 + 1, GFP_KERNEL);
466 for (i = 0; i < key_len; i++)
467 sprintf(f + i * 2, "%02x", v[i]);
468 pr_debug("authority %s\n", f);
469 ctx->cert->authority = f;
477 * Record a certificate time.
479 static int x509_note_time(struct tm *tm, size_t hdrlen,
481 const unsigned char *value, size_t vlen)
483 const unsigned char *p = value;
485 #define dec2bin(X) ((X) - '0')
486 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
488 if (tag == ASN1_UNITIM) {
489 /* UTCTime: YYMMDDHHMMSSZ */
491 goto unsupported_time;
492 tm->tm_year = DD2bin(p);
493 if (tm->tm_year >= 50)
497 } else if (tag == ASN1_GENTIM) {
498 /* GenTime: YYYYMMDDHHMMSSZ */
500 goto unsupported_time;
501 tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
503 goto unsupported_time;
507 tm->tm_mon = DD2bin(p) - 1;
508 tm->tm_mday = DD2bin(p);
509 tm->tm_hour = DD2bin(p);
510 tm->tm_min = DD2bin(p);
511 tm->tm_sec = DD2bin(p);
514 goto unsupported_time;
519 pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
520 tag, (int)vlen, (int)vlen, value);
524 int x509_note_not_before(void *context, size_t hdrlen,
526 const void *value, size_t vlen)
528 struct x509_parse_context *ctx = context;
529 return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
532 int x509_note_not_after(void *context, size_t hdrlen,
534 const void *value, size_t vlen)
536 struct x509_parse_context *ctx = context;
537 return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);