1 /**
2  * \file asn1.h
3  *
4  * \brief Generic ASN.1 parsing
5  */
6 /*
7  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
8  *  SPDX-License-Identifier: Apache-2.0
9  *
10  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
11  *  not use this file except in compliance with the License.
12  *  You may obtain a copy of the License at
13  *
14  *  http://www.apache.org/licenses/LICENSE-2.0
15  *
16  *  Unless required by applicable law or agreed to in writing, software
17  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
18  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19  *  See the License for the specific language governing permissions and
20  *  limitations under the License.
21  *
22  *  This file is part of mbed TLS (https://tls.mbed.org)
23  */
24 #ifndef MBEDTLS_ASN1_H
25 #define MBEDTLS_ASN1_H
26 
27 #if !defined(MBEDTLS_CONFIG_FILE)
28 #include "config.h"
29 #else
30 #include MBEDTLS_CONFIG_FILE
31 #endif
32 
33 #include <stddef.h>
34 
35 #if defined(MBEDTLS_BIGNUM_C)
36 #include "bignum.h"
37 #endif
38 
39 /**
40  * \addtogroup asn1_module
41  * \{
42  */
43 
44 /**
45  * \name ASN1 Error codes
46  * These error codes are OR'ed to X509 error codes for
47  * higher error granularity.
48  * ASN1 is a standard to specify data structures.
49  * \{
50  */
51 #define MBEDTLS_ERR_ASN1_OUT_OF_DATA                      -0x0060  /**< Out of data when parsing an ASN1 data structure. */
52 #define MBEDTLS_ERR_ASN1_UNEXPECTED_TAG                   -0x0062  /**< ASN1 tag was of an unexpected value. */
53 #define MBEDTLS_ERR_ASN1_INVALID_LENGTH                   -0x0064  /**< Error when trying to determine the length or invalid length. */
54 #define MBEDTLS_ERR_ASN1_LENGTH_MISMATCH                  -0x0066  /**< Actual length differs from expected length. */
55 #define MBEDTLS_ERR_ASN1_INVALID_DATA                     -0x0068  /**< Data is invalid. (not used) */
56 #define MBEDTLS_ERR_ASN1_ALLOC_FAILED                     -0x006A  /**< Memory allocation failed */
57 #define MBEDTLS_ERR_ASN1_BUF_TOO_SMALL                    -0x006C  /**< Buffer too small when writing ASN.1 data structure. */
58 
59 /* \} name */
60 
61 /**
62  * \name DER constants
63  * These constants comply with the DER encoded ASN.1 type tags.
64  * DER encoding uses hexadecimal representation.
65  * An example DER sequence is:\n
66  * - 0x02 -- tag indicating INTEGER
67  * - 0x01 -- length in octets
68  * - 0x05 -- value
69  * Such sequences are typically read into \c ::mbedtls_x509_buf.
70  * \{
71  */
72 #define MBEDTLS_ASN1_BOOLEAN                 0x01
73 #define MBEDTLS_ASN1_INTEGER                 0x02
74 #define MBEDTLS_ASN1_BIT_STRING              0x03
75 #define MBEDTLS_ASN1_OCTET_STRING            0x04
76 #define MBEDTLS_ASN1_NULL                    0x05
77 #define MBEDTLS_ASN1_OID                     0x06
78 #define MBEDTLS_ASN1_UTF8_STRING             0x0C
79 #define MBEDTLS_ASN1_SEQUENCE                0x10
80 #define MBEDTLS_ASN1_SET                     0x11
81 #define MBEDTLS_ASN1_PRINTABLE_STRING        0x13
82 #define MBEDTLS_ASN1_T61_STRING              0x14
83 #define MBEDTLS_ASN1_IA5_STRING              0x16
84 #define MBEDTLS_ASN1_UTC_TIME                0x17
85 #define MBEDTLS_ASN1_GENERALIZED_TIME        0x18
86 #define MBEDTLS_ASN1_UNIVERSAL_STRING        0x1C
87 #define MBEDTLS_ASN1_BMP_STRING              0x1E
88 #define MBEDTLS_ASN1_PRIMITIVE               0x00
89 #define MBEDTLS_ASN1_CONSTRUCTED             0x20
90 #define MBEDTLS_ASN1_CONTEXT_SPECIFIC        0x80
91 
92 /*
93  * Bit masks for each of the components of an ASN.1 tag as specified in
94  * ITU X.690 (08/2015), section 8.1 "General rules for encoding",
95  * paragraph 8.1.2.2:
96  *
97  * Bit  8     7   6   5          1
98  *     +-------+-----+------------+
99  *     | Class | P/C | Tag number |
100  *     +-------+-----+------------+
101  */
102 #define MBEDTLS_ASN1_TAG_CLASS_MASK          0xC0
103 #define MBEDTLS_ASN1_TAG_PC_MASK             0x20
104 #define MBEDTLS_ASN1_TAG_VALUE_MASK          0x1F
105 
106 /* \} name */
107 /* \} addtogroup asn1_module */
108 
109 /** Returns the size of the binary string, without the trailing \\0 */
110 #define MBEDTLS_OID_SIZE(x) (sizeof(x) - 1)
111 
112 /**
113  * Compares an mbedtls_asn1_buf structure to a reference OID.
114  *
115  * Only works for 'defined' oid_str values (MBEDTLS_OID_HMAC_SHA1), you cannot use a
116  * 'unsigned char *oid' here!
117  */
118 #define MBEDTLS_OID_CMP(oid_str, oid_buf)                                   \
119         ( ( MBEDTLS_OID_SIZE(oid_str) != (oid_buf)->len ) ||                \
120           memcmp( (oid_str), (oid_buf)->p, (oid_buf)->len) != 0 )
121 
122 #ifdef __cplusplus
123 extern "C" {
124 #endif
125 
126 /**
127  * \name Functions to parse ASN.1 data structures
128  * \{
129  */
130 
131 /**
132  * Type-length-value structure that allows for ASN1 using DER.
133  */
134 typedef struct mbedtls_asn1_buf
135 {
136     int tag;                /**< ASN1 type, e.g. MBEDTLS_ASN1_UTF8_STRING. */
137     size_t len;             /**< ASN1 length, in octets. */
138     unsigned char *p;       /**< ASN1 data, e.g. in ASCII. */
139 }
140 mbedtls_asn1_buf;
141 
142 /**
143  * Container for ASN1 bit strings.
144  */
145 typedef struct mbedtls_asn1_bitstring
146 {
147     size_t len;                 /**< ASN1 length, in octets. */
148     unsigned char unused_bits;  /**< Number of unused bits at the end of the string */
149     unsigned char *p;           /**< Raw ASN1 data for the bit string */
150 }
151 mbedtls_asn1_bitstring;
152 
153 /**
154  * Container for a sequence of ASN.1 items
155  */
156 typedef struct mbedtls_asn1_sequence
157 {
158     mbedtls_asn1_buf buf;                   /**< Buffer containing the given ASN.1 item. */
159     struct mbedtls_asn1_sequence *next;    /**< The next entry in the sequence. */
160 }
161 mbedtls_asn1_sequence;
162 
163 /**
164  * Container for a sequence or list of 'named' ASN.1 data items
165  */
166 typedef struct mbedtls_asn1_named_data
167 {
168     mbedtls_asn1_buf oid;                   /**< The object identifier. */
169     mbedtls_asn1_buf val;                   /**< The named value. */
170     struct mbedtls_asn1_named_data *next;  /**< The next entry in the sequence. */
171     unsigned char next_merged;      /**< Merge next item into the current one? */
172 }
173 mbedtls_asn1_named_data;
174 
175 /**
176  * \brief       Get the length of an ASN.1 element.
177  *              Updates the pointer to immediately behind the length.
178  *
179  * \param p     The position in the ASN.1 data
180  * \param end   End of data
181  * \param len   The variable that will receive the value
182  *
183  * \return      0 if successful, MBEDTLS_ERR_ASN1_OUT_OF_DATA on reaching
184  *              end of data, MBEDTLS_ERR_ASN1_INVALID_LENGTH if length is
185  *              unparseable.
186  */
187 int mbedtls_asn1_get_len( unsigned char **p,
188                   const unsigned char *end,
189                   size_t *len );
190 
191 /**
192  * \brief       Get the tag and length of the tag. Check for the requested tag.
193  *              Updates the pointer to immediately behind the tag and length.
194  *
195  * \param p     The position in the ASN.1 data
196  * \param end   End of data
197  * \param len   The variable that will receive the length
198  * \param tag   The expected tag
199  *
200  * \return      0 if successful, MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if tag did
201  *              not match requested tag, or another specific ASN.1 error code.
202  */
203 int mbedtls_asn1_get_tag( unsigned char **p,
204                   const unsigned char *end,
205                   size_t *len, int tag );
206 
207 /**
208  * \brief       Retrieve a boolean ASN.1 tag and its value.
209  *              Updates the pointer to immediately behind the full tag.
210  *
211  * \param p     The position in the ASN.1 data
212  * \param end   End of data
213  * \param val   The variable that will receive the value
214  *
215  * \return      0 if successful or a specific ASN.1 error code.
216  */
217 int mbedtls_asn1_get_bool( unsigned char **p,
218                    const unsigned char *end,
219                    int *val );
220 
221 /**
222  * \brief       Retrieve an integer ASN.1 tag and its value.
223  *              Updates the pointer to immediately behind the full tag.
224  *
225  * \param p     The position in the ASN.1 data
226  * \param end   End of data
227  * \param val   The variable that will receive the value
228  *
229  * \return      0 if successful or a specific ASN.1 error code.
230  */
231 int mbedtls_asn1_get_int( unsigned char **p,
232                   const unsigned char *end,
233                   int *val );
234 
235 /**
236  * \brief       Retrieve a bitstring ASN.1 tag and its value.
237  *              Updates the pointer to immediately behind the full tag.
238  *
239  * \param p     The position in the ASN.1 data
240  * \param end   End of data
241  * \param bs    The variable that will receive the value
242  *
243  * \return      0 if successful or a specific ASN.1 error code.
244  */
245 int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
246                         mbedtls_asn1_bitstring *bs);
247 
248 /**
249  * \brief       Retrieve a bitstring ASN.1 tag without unused bits and its
250  *              value.
251  *              Updates the pointer to the beginning of the bit/octet string.
252  *
253  * \param p     The position in the ASN.1 data
254  * \param end   End of data
255  * \param len   Length of the actual bit/octect string in bytes
256  *
257  * \return      0 if successful or a specific ASN.1 error code.
258  */
259 int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
260                              size_t *len );
261 
262 /**
263  * \brief       Parses and splits an ASN.1 "SEQUENCE OF <tag>"
264  *              Updated the pointer to immediately behind the full sequence tag.
265  *
266  * \param p     The position in the ASN.1 data
267  * \param end   End of data
268  * \param cur   First variable in the chain to fill
269  * \param tag   Type of sequence
270  *
271  * \return      0 if successful or a specific ASN.1 error code.
272  */
273 int mbedtls_asn1_get_sequence_of( unsigned char **p,
274                           const unsigned char *end,
275                           mbedtls_asn1_sequence *cur,
276                           int tag);
277 
278 #if defined(MBEDTLS_BIGNUM_C)
279 /**
280  * \brief       Retrieve a MPI value from an integer ASN.1 tag.
281  *              Updates the pointer to immediately behind the full tag.
282  *
283  * \param p     The position in the ASN.1 data
284  * \param end   End of data
285  * \param X     The MPI that will receive the value
286  *
287  * \return      0 if successful or a specific ASN.1 or MPI error code.
288  */
289 int mbedtls_asn1_get_mpi( unsigned char **p,
290                   const unsigned char *end,
291                   mbedtls_mpi *X );
292 #endif /* MBEDTLS_BIGNUM_C */
293 
294 /**
295  * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence.
296  *              Updates the pointer to immediately behind the full
297  *              AlgorithmIdentifier.
298  *
299  * \param p     The position in the ASN.1 data
300  * \param end   End of data
301  * \param alg   The buffer to receive the OID
302  * \param params The buffer to receive the params (if any)
303  *
304  * \return      0 if successful or a specific ASN.1 or MPI error code.
305  */
306 int mbedtls_asn1_get_alg( unsigned char **p,
307                   const unsigned char *end,
308                   mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params );
309 
310 /**
311  * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no
312  *              params.
313  *              Updates the pointer to immediately behind the full
314  *              AlgorithmIdentifier.
315  *
316  * \param p     The position in the ASN.1 data
317  * \param end   End of data
318  * \param alg   The buffer to receive the OID
319  *
320  * \return      0 if successful or a specific ASN.1 or MPI error code.
321  */
322 int mbedtls_asn1_get_alg_null( unsigned char **p,
323                        const unsigned char *end,
324                        mbedtls_asn1_buf *alg );
325 
326 /**
327  * \brief       Find a specific named_data entry in a sequence or list based on
328  *              the OID.
329  *
330  * \param list  The list to seek through
331  * \param oid   The OID to look for
332  * \param len   Size of the OID
333  *
334  * \return      NULL if not found, or a pointer to the existing entry.
335  */
336 mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
337                                        const char *oid, size_t len );
338 
339 /**
340  * \brief       Free a mbedtls_asn1_named_data entry
341  *
342  * \param entry The named data entry to free
343  */
344 void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *entry );
345 
346 /**
347  * \brief       Free all entries in a mbedtls_asn1_named_data list
348  *              Head will be set to NULL
349  *
350  * \param head  Pointer to the head of the list of named data entries to free
351  */
352 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head );
353 
354 #ifdef __cplusplus
355 }
356 #endif
357 
358 #endif /* asn1.h */
359