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 #if defined(MBEDTLS_PLATFORM_C)
46 #include "mbedtls/platform.h"
47 #else
48 #include <stdlib.h>
49 #include <stdio.h>
50 #define mbedtls_free free
51 #define mbedtls_calloc calloc
52 #define mbedtls_snprintf snprintf
53 #endif
54
55 #if defined(MBEDTLS_FS_IO) || defined(EFIX64) || defined(EFI32)
56 #include <stdio.h>
57 #endif
58
59 /*
60 * Version ::= INTEGER { v1(0) }
61 */
x509_csr_get_version(unsigned char ** p,const unsigned char * end,int * ver)62 static int x509_csr_get_version( unsigned char **p,
63 const unsigned char *end,
64 int *ver )
65 {
66 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
67
68 if( ( ret = mbedtls_asn1_get_int( p, end, ver ) ) != 0 )
69 {
70 if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
71 {
72 *ver = 0;
73 return( 0 );
74 }
75
76 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION, ret ) );
77 }
78
79 return( 0 );
80 }
81
82 /*
83 * Parse a CSR in DER format
84 */
mbedtls_x509_csr_parse_der(mbedtls_x509_csr * csr,const unsigned char * buf,size_t buflen)85 int mbedtls_x509_csr_parse_der( mbedtls_x509_csr *csr,
86 const unsigned char *buf, size_t buflen )
87 {
88 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
89 size_t len;
90 unsigned char *p, *end;
91 mbedtls_x509_buf sig_params;
92
93 memset( &sig_params, 0, sizeof( mbedtls_x509_buf ) );
94
95 /*
96 * Check for valid input
97 */
98 if( csr == NULL || buf == NULL || buflen == 0 )
99 return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
100
101 mbedtls_x509_csr_init( csr );
102
103 /*
104 * first copy the raw DER data
105 */
106 p = mbedtls_calloc( 1, len = buflen );
107
108 if( p == NULL )
109 return( MBEDTLS_ERR_X509_ALLOC_FAILED );
110
111 memcpy( p, buf, buflen );
112
113 csr->raw.p = p;
114 csr->raw.len = len;
115 end = p + len;
116
117 /*
118 * CertificationRequest ::= SEQUENCE {
119 * certificationRequestInfo CertificationRequestInfo,
120 * signatureAlgorithm AlgorithmIdentifier,
121 * signature BIT STRING
122 * }
123 */
124 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
125 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
126 {
127 mbedtls_x509_csr_free( csr );
128 return( MBEDTLS_ERR_X509_INVALID_FORMAT );
129 }
130
131 if( len != (size_t) ( end - p ) )
132 {
133 mbedtls_x509_csr_free( csr );
134 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
135 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
136 }
137
138 /*
139 * CertificationRequestInfo ::= SEQUENCE {
140 */
141 csr->cri.p = p;
142
143 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
144 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
145 {
146 mbedtls_x509_csr_free( csr );
147 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
148 }
149
150 end = p + len;
151 csr->cri.len = end - csr->cri.p;
152
153 /*
154 * Version ::= INTEGER { v1(0) }
155 */
156 if( ( ret = x509_csr_get_version( &p, end, &csr->version ) ) != 0 )
157 {
158 mbedtls_x509_csr_free( csr );
159 return( ret );
160 }
161
162 if( csr->version != 0 )
163 {
164 mbedtls_x509_csr_free( csr );
165 return( MBEDTLS_ERR_X509_UNKNOWN_VERSION );
166 }
167
168 csr->version++;
169
170 /*
171 * subject Name
172 */
173 csr->subject_raw.p = p;
174
175 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
176 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
177 {
178 mbedtls_x509_csr_free( csr );
179 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
180 }
181
182 if( ( ret = mbedtls_x509_get_name( &p, p + len, &csr->subject ) ) != 0 )
183 {
184 mbedtls_x509_csr_free( csr );
185 return( ret );
186 }
187
188 csr->subject_raw.len = p - csr->subject_raw.p;
189
190 /*
191 * subjectPKInfo SubjectPublicKeyInfo
192 */
193 if( ( ret = mbedtls_pk_parse_subpubkey( &p, end, &csr->pk ) ) != 0 )
194 {
195 mbedtls_x509_csr_free( csr );
196 return( ret );
197 }
198
199 /*
200 * attributes [0] Attributes
201 *
202 * The list of possible attributes is open-ended, though RFC 2985
203 * (PKCS#9) defines a few in section 5.4. We currently don't support any,
204 * so we just ignore them. This is a safe thing to do as the worst thing
205 * that could happen is that we issue a certificate that does not match
206 * the requester's expectations - this cannot cause a violation of our
207 * signature policies.
208 */
209 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
210 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 )
211 {
212 mbedtls_x509_csr_free( csr );
213 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
214 }
215
216 p += len;
217
218 end = csr->raw.p + csr->raw.len;
219
220 /*
221 * signatureAlgorithm AlgorithmIdentifier,
222 * signature BIT STRING
223 */
224 if( ( ret = mbedtls_x509_get_alg( &p, end, &csr->sig_oid, &sig_params ) ) != 0 )
225 {
226 mbedtls_x509_csr_free( csr );
227 return( ret );
228 }
229
230 if( ( ret = mbedtls_x509_get_sig_alg( &csr->sig_oid, &sig_params,
231 &csr->sig_md, &csr->sig_pk,
232 &csr->sig_opts ) ) != 0 )
233 {
234 mbedtls_x509_csr_free( csr );
235 return( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG );
236 }
237
238 if( ( ret = mbedtls_x509_get_sig( &p, end, &csr->sig ) ) != 0 )
239 {
240 mbedtls_x509_csr_free( csr );
241 return( ret );
242 }
243
244 if( p != end )
245 {
246 mbedtls_x509_csr_free( csr );
247 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
248 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
249 }
250
251 return( 0 );
252 }
253
254 /*
255 * Parse a CSR, allowing for PEM or raw DER encoding
256 */
mbedtls_x509_csr_parse(mbedtls_x509_csr * csr,const unsigned char * buf,size_t buflen)257 int mbedtls_x509_csr_parse( mbedtls_x509_csr *csr, const unsigned char *buf, size_t buflen )
258 {
259 #if defined(MBEDTLS_PEM_PARSE_C)
260 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
261 size_t use_len;
262 mbedtls_pem_context pem;
263 #endif
264
265 /*
266 * Check for valid input
267 */
268 if( csr == NULL || buf == NULL || buflen == 0 )
269 return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
270
271 #if defined(MBEDTLS_PEM_PARSE_C)
272 /* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */
273 if( buf[buflen - 1] == '\0' )
274 {
275 mbedtls_pem_init( &pem );
276 ret = mbedtls_pem_read_buffer( &pem,
277 "-----BEGIN CERTIFICATE REQUEST-----",
278 "-----END CERTIFICATE REQUEST-----",
279 buf, NULL, 0, &use_len );
280 if( ret == MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
281 {
282 ret = mbedtls_pem_read_buffer( &pem,
283 "-----BEGIN NEW CERTIFICATE REQUEST-----",
284 "-----END NEW CERTIFICATE REQUEST-----",
285 buf, NULL, 0, &use_len );
286 }
287
288 if( ret == 0 )
289 {
290 /*
291 * Was PEM encoded, parse the result
292 */
293 ret = mbedtls_x509_csr_parse_der( csr, pem.buf, pem.buflen );
294 }
295
296 mbedtls_pem_free( &pem );
297 if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
298 return( ret );
299 }
300 #endif /* MBEDTLS_PEM_PARSE_C */
301 return( mbedtls_x509_csr_parse_der( csr, buf, buflen ) );
302 }
303
304 #if defined(MBEDTLS_FS_IO)
305 /*
306 * Load a CSR into the structure
307 */
mbedtls_x509_csr_parse_file(mbedtls_x509_csr * csr,const char * path)308 int mbedtls_x509_csr_parse_file( mbedtls_x509_csr *csr, const char *path )
309 {
310 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
311 size_t n;
312 unsigned char *buf;
313
314 if( ( ret = mbedtls_pk_load_file( path, &buf, &n ) ) != 0 )
315 return( ret );
316
317 ret = mbedtls_x509_csr_parse( csr, buf, n );
318
319 mbedtls_platform_zeroize( buf, n );
320 mbedtls_free( buf );
321
322 return( ret );
323 }
324 #endif /* MBEDTLS_FS_IO */
325
326 #if !defined(MBEDTLS_X509_REMOVE_INFO)
327 #define BEFORE_COLON 14
328 #define BC "14"
329 /*
330 * Return an informational string about the CSR.
331 */
mbedtls_x509_csr_info(char * buf,size_t size,const char * prefix,const mbedtls_x509_csr * csr)332 int mbedtls_x509_csr_info( char *buf, size_t size, const char *prefix,
333 const mbedtls_x509_csr *csr )
334 {
335 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
336 size_t n;
337 char *p;
338 char key_size_str[BEFORE_COLON];
339
340 p = buf;
341 n = size;
342
343 ret = mbedtls_snprintf( p, n, "%sCSR version : %d",
344 prefix, csr->version );
345 MBEDTLS_X509_SAFE_SNPRINTF;
346
347 ret = mbedtls_snprintf( p, n, "\n%ssubject name : ", prefix );
348 MBEDTLS_X509_SAFE_SNPRINTF;
349 ret = mbedtls_x509_dn_gets( p, n, &csr->subject );
350 MBEDTLS_X509_SAFE_SNPRINTF;
351
352 ret = mbedtls_snprintf( p, n, "\n%ssigned using : ", prefix );
353 MBEDTLS_X509_SAFE_SNPRINTF;
354
355 ret = mbedtls_x509_sig_alg_gets( p, n, &csr->sig_oid, csr->sig_pk, csr->sig_md,
356 csr->sig_opts );
357 MBEDTLS_X509_SAFE_SNPRINTF;
358
359 if( ( ret = mbedtls_x509_key_size_helper( key_size_str, BEFORE_COLON,
360 mbedtls_pk_get_name( &csr->pk ) ) ) != 0 )
361 {
362 return( ret );
363 }
364
365 ret = mbedtls_snprintf( p, n, "\n%s%-" BC "s: %d bits\n", prefix, key_size_str,
366 (int) mbedtls_pk_get_bitlen( &csr->pk ) );
367 MBEDTLS_X509_SAFE_SNPRINTF;
368
369 return( (int) ( size - n ) );
370 }
371 #endif /* MBEDTLS_X509_REMOVE_INFO */
372
373 /*
374 * Initialize a CSR
375 */
mbedtls_x509_csr_init(mbedtls_x509_csr * csr)376 void mbedtls_x509_csr_init( mbedtls_x509_csr *csr )
377 {
378 memset( csr, 0, sizeof(mbedtls_x509_csr) );
379 }
380
381 /*
382 * Unallocate all CSR data
383 */
mbedtls_x509_csr_free(mbedtls_x509_csr * csr)384 void mbedtls_x509_csr_free( mbedtls_x509_csr *csr )
385 {
386 mbedtls_x509_name *name_cur;
387 mbedtls_x509_name *name_prv;
388
389 if( csr == NULL )
390 return;
391
392 mbedtls_pk_free( &csr->pk );
393
394 #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
395 mbedtls_free( csr->sig_opts );
396 #endif
397
398 name_cur = csr->subject.next;
399 while( name_cur != NULL )
400 {
401 name_prv = name_cur;
402 name_cur = name_cur->next;
403 mbedtls_platform_zeroize( name_prv, sizeof( mbedtls_x509_name ) );
404 mbedtls_free( name_prv );
405 }
406
407 if( csr->raw.p != NULL )
408 {
409 mbedtls_platform_zeroize( csr->raw.p, csr->raw.len );
410 mbedtls_free( csr->raw.p );
411 }
412
413 mbedtls_platform_zeroize( csr, sizeof( mbedtls_x509_csr ) );
414 }
415
416 #endif /* MBEDTLS_X509_CSR_PARSE_C */
417