1 /*
2 * X.509 Certificate Signing Request (CSR) parsing
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 */
19 /*
20 * The ITU-T X.509 standard defines a certificate format for PKI.
21 *
22 * http://www.ietf.org/rfc/rfc5280.txt (Certificates and CRLs)
23 * http://www.ietf.org/rfc/rfc3279.txt (Alg IDs for CRLs)
24 * http://www.ietf.org/rfc/rfc2986.txt (CSRs, aka PKCS#10)
25 *
26 * http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-0207.pdf
27 * http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
28 */
29
30 #include "common.h"
31
32 #if defined(MBEDTLS_X509_CSR_PARSE_C)
33
34 #include "mbedtls/x509_csr.h"
35 #include "mbedtls/error.h"
36 #include "mbedtls/oid.h"
37 #include "mbedtls/platform_util.h"
38
39 #include <string.h>
40
41 #if defined(MBEDTLS_PEM_PARSE_C)
42 #include "mbedtls/pem.h"
43 #endif
44
45 #include "mbedtls/platform.h"
46
47 #if defined(MBEDTLS_FS_IO) || defined(EFIX64) || defined(EFI32)
48 #include <stdio.h>
49 #endif
50
51 /*
52 * Version ::= INTEGER { v1(0) }
53 */
x509_csr_get_version(unsigned char ** p,const unsigned char * end,int * ver)54 static int x509_csr_get_version( unsigned char **p,
55 const unsigned char *end,
56 int *ver )
57 {
58 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
59
60 if( ( ret = mbedtls_asn1_get_int( p, end, ver ) ) != 0 )
61 {
62 if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
63 {
64 *ver = 0;
65 return( 0 );
66 }
67
68 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION, ret ) );
69 }
70
71 return( 0 );
72 }
73
74 /*
75 * Parse a CSR in DER format
76 */
mbedtls_x509_csr_parse_der(mbedtls_x509_csr * csr,const unsigned char * buf,size_t buflen)77 int mbedtls_x509_csr_parse_der( mbedtls_x509_csr *csr,
78 const unsigned char *buf, size_t buflen )
79 {
80 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
81 size_t len;
82 unsigned char *p, *end;
83 mbedtls_x509_buf sig_params;
84
85 memset( &sig_params, 0, sizeof( mbedtls_x509_buf ) );
86
87 /*
88 * Check for valid input
89 */
90 if( csr == NULL || buf == NULL || buflen == 0 )
91 return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
92
93 mbedtls_x509_csr_init( csr );
94
95 /*
96 * first copy the raw DER data
97 */
98 p = mbedtls_calloc( 1, len = buflen );
99
100 if( p == NULL )
101 return( MBEDTLS_ERR_X509_ALLOC_FAILED );
102
103 memcpy( p, buf, buflen );
104
105 csr->raw.p = p;
106 csr->raw.len = len;
107 end = p + len;
108
109 /*
110 * CertificationRequest ::= SEQUENCE {
111 * certificationRequestInfo CertificationRequestInfo,
112 * signatureAlgorithm AlgorithmIdentifier,
113 * signature BIT STRING
114 * }
115 */
116 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
117 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
118 {
119 mbedtls_x509_csr_free( csr );
120 return( MBEDTLS_ERR_X509_INVALID_FORMAT );
121 }
122
123 if( len != (size_t) ( end - p ) )
124 {
125 mbedtls_x509_csr_free( csr );
126 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
127 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
128 }
129
130 /*
131 * CertificationRequestInfo ::= SEQUENCE {
132 */
133 csr->cri.p = p;
134
135 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
136 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
137 {
138 mbedtls_x509_csr_free( csr );
139 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
140 }
141
142 end = p + len;
143 csr->cri.len = end - csr->cri.p;
144
145 /*
146 * Version ::= INTEGER { v1(0) }
147 */
148 if( ( ret = x509_csr_get_version( &p, end, &csr->version ) ) != 0 )
149 {
150 mbedtls_x509_csr_free( csr );
151 return( ret );
152 }
153
154 if( csr->version != 0 )
155 {
156 mbedtls_x509_csr_free( csr );
157 return( MBEDTLS_ERR_X509_UNKNOWN_VERSION );
158 }
159
160 csr->version++;
161
162 /*
163 * subject Name
164 */
165 csr->subject_raw.p = p;
166
167 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
168 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
169 {
170 mbedtls_x509_csr_free( csr );
171 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
172 }
173
174 if( ( ret = mbedtls_x509_get_name( &p, p + len, &csr->subject ) ) != 0 )
175 {
176 mbedtls_x509_csr_free( csr );
177 return( ret );
178 }
179
180 csr->subject_raw.len = p - csr->subject_raw.p;
181
182 /*
183 * subjectPKInfo SubjectPublicKeyInfo
184 */
185 if( ( ret = mbedtls_pk_parse_subpubkey( &p, end, &csr->pk ) ) != 0 )
186 {
187 mbedtls_x509_csr_free( csr );
188 return( ret );
189 }
190
191 /*
192 * attributes [0] Attributes
193 *
194 * The list of possible attributes is open-ended, though RFC 2985
195 * (PKCS#9) defines a few in section 5.4. We currently don't support any,
196 * so we just ignore them. This is a safe thing to do as the worst thing
197 * that could happen is that we issue a certificate that does not match
198 * the requester's expectations - this cannot cause a violation of our
199 * signature policies.
200 */
201 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
202 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 )
203 {
204 mbedtls_x509_csr_free( csr );
205 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
206 }
207
208 p += len;
209
210 end = csr->raw.p + csr->raw.len;
211
212 /*
213 * signatureAlgorithm AlgorithmIdentifier,
214 * signature BIT STRING
215 */
216 if( ( ret = mbedtls_x509_get_alg( &p, end, &csr->sig_oid, &sig_params ) ) != 0 )
217 {
218 mbedtls_x509_csr_free( csr );
219 return( ret );
220 }
221
222 if( ( ret = mbedtls_x509_get_sig_alg( &csr->sig_oid, &sig_params,
223 &csr->sig_md, &csr->sig_pk,
224 &csr->sig_opts ) ) != 0 )
225 {
226 mbedtls_x509_csr_free( csr );
227 return( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG );
228 }
229
230 if( ( ret = mbedtls_x509_get_sig( &p, end, &csr->sig ) ) != 0 )
231 {
232 mbedtls_x509_csr_free( csr );
233 return( ret );
234 }
235
236 if( p != end )
237 {
238 mbedtls_x509_csr_free( csr );
239 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
240 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
241 }
242
243 return( 0 );
244 }
245
246 /*
247 * Parse a CSR, allowing for PEM or raw DER encoding
248 */
mbedtls_x509_csr_parse(mbedtls_x509_csr * csr,const unsigned char * buf,size_t buflen)249 int mbedtls_x509_csr_parse( mbedtls_x509_csr *csr, const unsigned char *buf, size_t buflen )
250 {
251 #if defined(MBEDTLS_PEM_PARSE_C)
252 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
253 size_t use_len;
254 mbedtls_pem_context pem;
255 #endif
256
257 /*
258 * Check for valid input
259 */
260 if( csr == NULL || buf == NULL || buflen == 0 )
261 return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
262
263 #if defined(MBEDTLS_PEM_PARSE_C)
264 /* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */
265 if( buf[buflen - 1] == '\0' )
266 {
267 mbedtls_pem_init( &pem );
268 ret = mbedtls_pem_read_buffer( &pem,
269 "-----BEGIN CERTIFICATE REQUEST-----",
270 "-----END CERTIFICATE REQUEST-----",
271 buf, NULL, 0, &use_len );
272 if( ret == MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
273 {
274 ret = mbedtls_pem_read_buffer( &pem,
275 "-----BEGIN NEW CERTIFICATE REQUEST-----",
276 "-----END NEW CERTIFICATE REQUEST-----",
277 buf, NULL, 0, &use_len );
278 }
279
280 if( ret == 0 )
281 {
282 /*
283 * Was PEM encoded, parse the result
284 */
285 ret = mbedtls_x509_csr_parse_der( csr, pem.buf, pem.buflen );
286 }
287
288 mbedtls_pem_free( &pem );
289 if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
290 return( ret );
291 }
292 #endif /* MBEDTLS_PEM_PARSE_C */
293 return( mbedtls_x509_csr_parse_der( csr, buf, buflen ) );
294 }
295
296 #if defined(MBEDTLS_FS_IO)
297 /*
298 * Load a CSR into the structure
299 */
mbedtls_x509_csr_parse_file(mbedtls_x509_csr * csr,const char * path)300 int mbedtls_x509_csr_parse_file( mbedtls_x509_csr *csr, const char *path )
301 {
302 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
303 size_t n;
304 unsigned char *buf;
305
306 if( ( ret = mbedtls_pk_load_file( path, &buf, &n ) ) != 0 )
307 return( ret );
308
309 ret = mbedtls_x509_csr_parse( csr, buf, n );
310
311 mbedtls_platform_zeroize( buf, n );
312 mbedtls_free( buf );
313
314 return( ret );
315 }
316 #endif /* MBEDTLS_FS_IO */
317
318 #if !defined(MBEDTLS_X509_REMOVE_INFO)
319 #define BEFORE_COLON 14
320 #define BC "14"
321 /*
322 * Return an informational string about the CSR.
323 */
mbedtls_x509_csr_info(char * buf,size_t size,const char * prefix,const mbedtls_x509_csr * csr)324 int mbedtls_x509_csr_info( char *buf, size_t size, const char *prefix,
325 const mbedtls_x509_csr *csr )
326 {
327 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
328 size_t n;
329 char *p;
330 char key_size_str[BEFORE_COLON];
331
332 p = buf;
333 n = size;
334
335 ret = mbedtls_snprintf( p, n, "%sCSR version : %d",
336 prefix, csr->version );
337 MBEDTLS_X509_SAFE_SNPRINTF;
338
339 ret = mbedtls_snprintf( p, n, "\n%ssubject name : ", prefix );
340 MBEDTLS_X509_SAFE_SNPRINTF;
341 ret = mbedtls_x509_dn_gets( p, n, &csr->subject );
342 MBEDTLS_X509_SAFE_SNPRINTF;
343
344 ret = mbedtls_snprintf( p, n, "\n%ssigned using : ", prefix );
345 MBEDTLS_X509_SAFE_SNPRINTF;
346
347 ret = mbedtls_x509_sig_alg_gets( p, n, &csr->sig_oid, csr->sig_pk, csr->sig_md,
348 csr->sig_opts );
349 MBEDTLS_X509_SAFE_SNPRINTF;
350
351 if( ( ret = mbedtls_x509_key_size_helper( key_size_str, BEFORE_COLON,
352 mbedtls_pk_get_name( &csr->pk ) ) ) != 0 )
353 {
354 return( ret );
355 }
356
357 ret = mbedtls_snprintf( p, n, "\n%s%-" BC "s: %d bits\n", prefix, key_size_str,
358 (int) mbedtls_pk_get_bitlen( &csr->pk ) );
359 MBEDTLS_X509_SAFE_SNPRINTF;
360
361 return( (int) ( size - n ) );
362 }
363 #endif /* MBEDTLS_X509_REMOVE_INFO */
364
365 /*
366 * Initialize a CSR
367 */
mbedtls_x509_csr_init(mbedtls_x509_csr * csr)368 void mbedtls_x509_csr_init( mbedtls_x509_csr *csr )
369 {
370 memset( csr, 0, sizeof(mbedtls_x509_csr) );
371 }
372
373 /*
374 * Unallocate all CSR data
375 */
mbedtls_x509_csr_free(mbedtls_x509_csr * csr)376 void mbedtls_x509_csr_free( mbedtls_x509_csr *csr )
377 {
378 if( csr == NULL )
379 return;
380
381 mbedtls_pk_free( &csr->pk );
382
383 #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
384 mbedtls_free( csr->sig_opts );
385 #endif
386
387 mbedtls_asn1_free_named_data_list_shallow( csr->subject.next );
388
389 if( csr->raw.p != NULL )
390 {
391 mbedtls_platform_zeroize( csr->raw.p, csr->raw.len );
392 mbedtls_free( csr->raw.p );
393 }
394
395 mbedtls_platform_zeroize( csr, sizeof( mbedtls_x509_csr ) );
396 }
397
398 #endif /* MBEDTLS_X509_CSR_PARSE_C */
399
