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Paul Bakkerbdb912d2012-02-13 23:11:30 +00001/*
2 * ASN.1 buffer writing functionality
3 *
Bence Szépkúti1e148272020-08-07 13:07:28 +02004 * Copyright The Mbed TLS Contributors
Manuel Pégourié-Gonnard37ff1402015-09-04 14:21:07 +02005 * 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.
Paul Bakkerbdb912d2012-02-13 23:11:30 +000018 */
19
Gilles Peskinedb09ef62020-06-03 01:43:33 +020020#include "common.h"
Paul Bakkerbdb912d2012-02-13 23:11:30 +000021
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +020022#if defined(MBEDTLS_ASN1_WRITE_C)
Paul Bakkerbdb912d2012-02-13 23:11:30 +000023
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000024#include "mbedtls/asn1write.h"
Janos Follath24eed8d2019-11-22 13:21:35 +000025#include "mbedtls/error.h"
Paul Bakkerbdb912d2012-02-13 23:11:30 +000026
Rich Evans00ab4702015-02-06 13:43:58 +000027#include <string.h>
28
Manuel Pégourié-Gonnard7f809972015-03-09 17:05:11 +000029#include "mbedtls/platform.h"
Paul Bakker59ba59f2013-09-09 11:26:00 +020030
Gilles Peskine449bd832023-01-11 14:50:10 +010031int mbedtls_asn1_write_len(unsigned char **p, const unsigned char *start, size_t len)
Paul Bakkerbdb912d2012-02-13 23:11:30 +000032{
Gilles Peskine449bd832023-01-11 14:50:10 +010033 if (len < 0x80) {
34 if (*p - start < 1) {
35 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
36 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +000037
Paul Bakkerb9cfaa02013-10-11 18:58:55 +020038 *--(*p) = (unsigned char) len;
Gilles Peskine449bd832023-01-11 14:50:10 +010039 return 1;
Paul Bakkerbdb912d2012-02-13 23:11:30 +000040 }
41
Gilles Peskine449bd832023-01-11 14:50:10 +010042 if (len <= 0xFF) {
43 if (*p - start < 2) {
44 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
45 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +000046
Paul Bakkerb9cfaa02013-10-11 18:58:55 +020047 *--(*p) = (unsigned char) len;
Paul Bakkerbdb912d2012-02-13 23:11:30 +000048 *--(*p) = 0x81;
Gilles Peskine449bd832023-01-11 14:50:10 +010049 return 2;
Paul Bakkerbdb912d2012-02-13 23:11:30 +000050 }
51
Gilles Peskine449bd832023-01-11 14:50:10 +010052 if (len <= 0xFFFF) {
53 if (*p - start < 3) {
54 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
55 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +000056
Gilles Peskine449bd832023-01-11 14:50:10 +010057 *--(*p) = MBEDTLS_BYTE_0(len);
58 *--(*p) = MBEDTLS_BYTE_1(len);
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010059 *--(*p) = 0x82;
Gilles Peskine449bd832023-01-11 14:50:10 +010060 return 3;
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010061 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +000062
Gilles Peskine449bd832023-01-11 14:50:10 +010063 if (len <= 0xFFFFFF) {
64 if (*p - start < 4) {
65 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
66 }
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010067
Gilles Peskine449bd832023-01-11 14:50:10 +010068 *--(*p) = MBEDTLS_BYTE_0(len);
69 *--(*p) = MBEDTLS_BYTE_1(len);
70 *--(*p) = MBEDTLS_BYTE_2(len);
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010071 *--(*p) = 0x83;
Gilles Peskine449bd832023-01-11 14:50:10 +010072 return 4;
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010073 }
74
David Horstmann059848f2022-10-25 10:16:45 +010075 int len_is_valid = 1;
Azim Khan45b79cf2018-05-23 16:55:16 +010076#if SIZE_MAX > 0xFFFFFFFF
Gilles Peskine449bd832023-01-11 14:50:10 +010077 len_is_valid = (len <= 0xFFFFFFFF);
Azim Khan45b79cf2018-05-23 16:55:16 +010078#endif
Gilles Peskine449bd832023-01-11 14:50:10 +010079 if (len_is_valid) {
80 if (*p - start < 5) {
81 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
82 }
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010083
Gilles Peskine449bd832023-01-11 14:50:10 +010084 *--(*p) = MBEDTLS_BYTE_0(len);
85 *--(*p) = MBEDTLS_BYTE_1(len);
86 *--(*p) = MBEDTLS_BYTE_2(len);
87 *--(*p) = MBEDTLS_BYTE_3(len);
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010088 *--(*p) = 0x84;
Gilles Peskine449bd832023-01-11 14:50:10 +010089 return 5;
Paul Bakkerc7d6bd42016-07-14 11:39:56 +010090 }
91
Gilles Peskine449bd832023-01-11 14:50:10 +010092 return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
Paul Bakkerbdb912d2012-02-13 23:11:30 +000093}
94
Gilles Peskine449bd832023-01-11 14:50:10 +010095int mbedtls_asn1_write_tag(unsigned char **p, const unsigned char *start, unsigned char tag)
Paul Bakkerbdb912d2012-02-13 23:11:30 +000096{
Gilles Peskine449bd832023-01-11 14:50:10 +010097 if (*p - start < 1) {
98 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
99 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000100
101 *--(*p) = tag;
102
Gilles Peskine449bd832023-01-11 14:50:10 +0100103 return 1;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000104}
105
Gilles Peskine449bd832023-01-11 14:50:10 +0100106int mbedtls_asn1_write_raw_buffer(unsigned char **p, const unsigned char *start,
107 const unsigned char *buf, size_t size)
Paul Bakker9852d002013-08-26 17:56:37 +0200108{
109 size_t len = 0;
110
Gilles Peskine449bd832023-01-11 14:50:10 +0100111 if (*p < start || (size_t) (*p - start) < size) {
112 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
113 }
Paul Bakker9852d002013-08-26 17:56:37 +0200114
115 len = size;
116 (*p) -= len;
Gilles Peskine449bd832023-01-11 14:50:10 +0100117 memcpy(*p, buf, len);
Paul Bakker9852d002013-08-26 17:56:37 +0200118
Gilles Peskine449bd832023-01-11 14:50:10 +0100119 return (int) len;
Paul Bakker9852d002013-08-26 17:56:37 +0200120}
121
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200122#if defined(MBEDTLS_BIGNUM_C)
Gilles Peskine449bd832023-01-11 14:50:10 +0100123int mbedtls_asn1_write_mpi(unsigned char **p, const unsigned char *start, const mbedtls_mpi *X)
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000124{
Janos Follath24eed8d2019-11-22 13:21:35 +0000125 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000126 size_t len = 0;
127
128 // Write the MPI
129 //
Gilles Peskine449bd832023-01-11 14:50:10 +0100130 len = mbedtls_mpi_size(X);
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000131
Gilles Peskine321a0892022-06-10 20:13:33 +0200132 /* DER represents 0 with a sign bit (0=nonnegative) and 7 value bits, not
133 * as 0 digits. We need to end up with 020100, not with 0200. */
Gilles Peskine449bd832023-01-11 14:50:10 +0100134 if (len == 0) {
Gilles Peskine321a0892022-06-10 20:13:33 +0200135 len = 1;
Gilles Peskine449bd832023-01-11 14:50:10 +0100136 }
Gilles Peskine321a0892022-06-10 20:13:33 +0200137
Gilles Peskine449bd832023-01-11 14:50:10 +0100138 if (*p < start || (size_t) (*p - start) < len) {
139 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
140 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000141
142 (*p) -= len;
Gilles Peskine449bd832023-01-11 14:50:10 +0100143 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(X, *p, len));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000144
145 // DER format assumes 2s complement for numbers, so the leftmost bit
146 // should be 0 for positive numbers and 1 for negative numbers.
147 //
Gilles Peskine449bd832023-01-11 14:50:10 +0100148 if (X->s == 1 && **p & 0x80) {
149 if (*p - start < 1) {
150 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
151 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000152
153 *--(*p) = 0x00;
154 len += 1;
155 }
156
Gilles Peskine449bd832023-01-11 14:50:10 +0100157 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
158 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_INTEGER));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000159
Paul Bakker3d8fb632014-04-17 12:42:41 +0200160 ret = (int) len;
161
162cleanup:
Gilles Peskine449bd832023-01-11 14:50:10 +0100163 return ret;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000164}
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200165#endif /* MBEDTLS_BIGNUM_C */
Paul Bakkered27a042013-04-18 22:46:23 +0200166
Gilles Peskine449bd832023-01-11 14:50:10 +0100167int mbedtls_asn1_write_null(unsigned char **p, const unsigned char *start)
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000168{
Janos Follath24eed8d2019-11-22 13:21:35 +0000169 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000170 size_t len = 0;
171
172 // Write NULL
173 //
Gilles Peskine449bd832023-01-11 14:50:10 +0100174 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, 0));
175 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_NULL));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000176
Gilles Peskine449bd832023-01-11 14:50:10 +0100177 return (int) len;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000178}
179
Gilles Peskine449bd832023-01-11 14:50:10 +0100180int mbedtls_asn1_write_oid(unsigned char **p, const unsigned char *start,
181 const char *oid, size_t oid_len)
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000182{
Janos Follath24eed8d2019-11-22 13:21:35 +0000183 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000184 size_t len = 0;
185
Gilles Peskine449bd832023-01-11 14:50:10 +0100186 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
187 (const unsigned char *) oid, oid_len));
188 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
189 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OID));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000190
Gilles Peskine449bd832023-01-11 14:50:10 +0100191 return (int) len;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000192}
193
Gilles Peskine449bd832023-01-11 14:50:10 +0100194int mbedtls_asn1_write_algorithm_identifier(unsigned char **p, const unsigned char *start,
195 const char *oid, size_t oid_len,
196 size_t par_len)
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000197{
Jethro Beekman01672442023-04-19 14:08:14 +0200198 return mbedtls_asn1_write_algorithm_identifier_ext(p, start, oid, oid_len, par_len, 1);
199}
200
201int mbedtls_asn1_write_algorithm_identifier_ext(unsigned char **p, const unsigned char *start,
202 const char *oid, size_t oid_len,
203 size_t par_len, int has_par)
204{
Janos Follath24eed8d2019-11-22 13:21:35 +0000205 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000206 size_t len = 0;
207
Jethro Beekman01672442023-04-19 14:08:14 +0200208 if (has_par) {
209 if (par_len == 0) {
210 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_null(p, start));
211 } else {
212 len += par_len;
213 }
Gilles Peskine449bd832023-01-11 14:50:10 +0100214 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000215
Gilles Peskine449bd832023-01-11 14:50:10 +0100216 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000217
Gilles Peskine449bd832023-01-11 14:50:10 +0100218 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
219 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
220 MBEDTLS_ASN1_CONSTRUCTED |
221 MBEDTLS_ASN1_SEQUENCE));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000222
Gilles Peskine449bd832023-01-11 14:50:10 +0100223 return (int) len;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000224}
225
Gilles Peskine449bd832023-01-11 14:50:10 +0100226int mbedtls_asn1_write_bool(unsigned char **p, const unsigned char *start, int boolean)
Paul Bakker329def32013-09-06 16:34:38 +0200227{
Janos Follath24eed8d2019-11-22 13:21:35 +0000228 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakker329def32013-09-06 16:34:38 +0200229 size_t len = 0;
230
Gilles Peskine449bd832023-01-11 14:50:10 +0100231 if (*p - start < 1) {
232 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
233 }
Paul Bakker329def32013-09-06 16:34:38 +0200234
Jonathan Leroy87c96c22015-10-14 09:41:56 +0200235 *--(*p) = (boolean) ? 255 : 0;
Paul Bakker329def32013-09-06 16:34:38 +0200236 len++;
237
Gilles Peskine449bd832023-01-11 14:50:10 +0100238 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
239 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_BOOLEAN));
Paul Bakker329def32013-09-06 16:34:38 +0200240
Gilles Peskine449bd832023-01-11 14:50:10 +0100241 return (int) len;
Paul Bakker329def32013-09-06 16:34:38 +0200242}
243
Gilles Peskine449bd832023-01-11 14:50:10 +0100244static int asn1_write_tagged_int(unsigned char **p, const unsigned char *start, int val, int tag)
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000245{
Janos Follath24eed8d2019-11-22 13:21:35 +0000246 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000247 size_t len = 0;
248
Gilles Peskine449bd832023-01-11 14:50:10 +0100249 do {
250 if (*p - start < 1) {
251 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
252 }
Gilles Peskine1dbab672019-03-01 18:15:18 +0100253 len += 1;
254 *--(*p) = val & 0xff;
255 val >>= 8;
Gilles Peskine449bd832023-01-11 14:50:10 +0100256 } while (val > 0);
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000257
Gilles Peskine449bd832023-01-11 14:50:10 +0100258 if (**p & 0x80) {
259 if (*p - start < 1) {
260 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
261 }
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000262 *--(*p) = 0x00;
263 len += 1;
264 }
265
Gilles Peskine449bd832023-01-11 14:50:10 +0100266 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
267 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, tag));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000268
Gilles Peskine449bd832023-01-11 14:50:10 +0100269 return (int) len;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000270}
271
Gilles Peskine449bd832023-01-11 14:50:10 +0100272int mbedtls_asn1_write_int(unsigned char **p, const unsigned char *start, int val)
Mykhailo Sopiha20180ca2019-10-29 15:58:10 +0200273{
Gilles Peskine449bd832023-01-11 14:50:10 +0100274 return asn1_write_tagged_int(p, start, val, MBEDTLS_ASN1_INTEGER);
Mykhailo Sopiha20180ca2019-10-29 15:58:10 +0200275}
276
Gilles Peskine449bd832023-01-11 14:50:10 +0100277int mbedtls_asn1_write_enum(unsigned char **p, const unsigned char *start, int val)
Mykhailo Sopiha20180ca2019-10-29 15:58:10 +0200278{
Gilles Peskine449bd832023-01-11 14:50:10 +0100279 return asn1_write_tagged_int(p, start, val, MBEDTLS_ASN1_ENUMERATED);
Mykhailo Sopiha20180ca2019-10-29 15:58:10 +0200280}
281
Gilles Peskine449bd832023-01-11 14:50:10 +0100282int mbedtls_asn1_write_tagged_string(unsigned char **p, const unsigned char *start, int tag,
283 const char *text, size_t text_len)
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000284{
Janos Follath24eed8d2019-11-22 13:21:35 +0000285 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000286 size_t len = 0;
287
Gilles Peskine449bd832023-01-11 14:50:10 +0100288 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
289 (const unsigned char *) text,
290 text_len));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000291
Gilles Peskine449bd832023-01-11 14:50:10 +0100292 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
293 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, tag));
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000294
Gilles Peskine449bd832023-01-11 14:50:10 +0100295 return (int) len;
Paul Bakkerbdb912d2012-02-13 23:11:30 +0000296}
Paul Bakker598e4502013-08-25 14:46:39 +0200297
Gilles Peskine449bd832023-01-11 14:50:10 +0100298int mbedtls_asn1_write_utf8_string(unsigned char **p, const unsigned char *start,
299 const char *text, size_t text_len)
Jaeden Amero23f954d2018-05-17 11:46:13 +0100300{
Gilles Peskine449bd832023-01-11 14:50:10 +0100301 return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len);
Jaeden Amero23f954d2018-05-17 11:46:13 +0100302}
303
Gilles Peskine449bd832023-01-11 14:50:10 +0100304int mbedtls_asn1_write_printable_string(unsigned char **p, const unsigned char *start,
305 const char *text, size_t text_len)
Jaeden Amero23f954d2018-05-17 11:46:13 +0100306{
Gilles Peskine449bd832023-01-11 14:50:10 +0100307 return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text,
308 text_len);
Jaeden Amero23f954d2018-05-17 11:46:13 +0100309}
310
Gilles Peskine449bd832023-01-11 14:50:10 +0100311int mbedtls_asn1_write_ia5_string(unsigned char **p, const unsigned char *start,
312 const char *text, size_t text_len)
Paul Bakker05888152012-02-16 10:26:57 +0000313{
Gilles Peskine449bd832023-01-11 14:50:10 +0100314 return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len);
Paul Bakker05888152012-02-16 10:26:57 +0000315}
Paul Bakker598e4502013-08-25 14:46:39 +0200316
Gilles Peskine449bd832023-01-11 14:50:10 +0100317int mbedtls_asn1_write_named_bitstring(unsigned char **p,
318 const unsigned char *start,
319 const unsigned char *buf,
320 size_t bits)
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100321{
322 size_t unused_bits, byte_len;
323 const unsigned char *cur_byte;
324 unsigned char cur_byte_shifted;
325 unsigned char bit;
326
Gilles Peskine449bd832023-01-11 14:50:10 +0100327 byte_len = (bits + 7) / 8;
328 unused_bits = (byte_len * 8) - bits;
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100329
330 /*
331 * Named bitstrings require that trailing 0s are excluded in the encoding
332 * of the bitstring. Trailing 0s are considered part of the 'unused' bits
333 * when encoding this value in the first content octet
334 */
Gilles Peskine449bd832023-01-11 14:50:10 +0100335 if (bits != 0) {
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100336 cur_byte = buf + byte_len - 1;
337 cur_byte_shifted = *cur_byte >> unused_bits;
338
Gilles Peskine449bd832023-01-11 14:50:10 +0100339 for (;;) {
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100340 bit = cur_byte_shifted & 0x1;
341 cur_byte_shifted >>= 1;
342
Gilles Peskine449bd832023-01-11 14:50:10 +0100343 if (bit != 0) {
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100344 break;
Gilles Peskine449bd832023-01-11 14:50:10 +0100345 }
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100346
347 bits--;
Gilles Peskine449bd832023-01-11 14:50:10 +0100348 if (bits == 0) {
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100349 break;
Gilles Peskine449bd832023-01-11 14:50:10 +0100350 }
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100351
Gilles Peskine449bd832023-01-11 14:50:10 +0100352 if (bits % 8 == 0) {
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100353 cur_byte_shifted = *--cur_byte;
Gilles Peskine449bd832023-01-11 14:50:10 +0100354 }
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100355 }
356 }
357
Gilles Peskine449bd832023-01-11 14:50:10 +0100358 return mbedtls_asn1_write_bitstring(p, start, buf, bits);
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100359}
360
Gilles Peskine449bd832023-01-11 14:50:10 +0100361int mbedtls_asn1_write_bitstring(unsigned char **p, const unsigned char *start,
362 const unsigned char *buf, size_t bits)
Paul Bakker598e4502013-08-25 14:46:39 +0200363{
Janos Follath24eed8d2019-11-22 13:21:35 +0000364 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100365 size_t len = 0;
366 size_t unused_bits, byte_len;
Paul Bakker598e4502013-08-25 14:46:39 +0200367
Gilles Peskine449bd832023-01-11 14:50:10 +0100368 byte_len = (bits + 7) / 8;
369 unused_bits = (byte_len * 8) - bits;
Paul Bakker598e4502013-08-25 14:46:39 +0200370
Gilles Peskine449bd832023-01-11 14:50:10 +0100371 if (*p < start || (size_t) (*p - start) < byte_len + 1) {
372 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
373 }
Paul Bakker598e4502013-08-25 14:46:39 +0200374
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100375 len = byte_len + 1;
Paul Bakker598e4502013-08-25 14:46:39 +0200376
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100377 /* Write the bitstring. Ensure the unused bits are zeroed */
Gilles Peskine449bd832023-01-11 14:50:10 +0100378 if (byte_len > 0) {
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100379 byte_len--;
Gilles Peskine449bd832023-01-11 14:50:10 +0100380 *--(*p) = buf[byte_len] & ~((0x1 << unused_bits) - 1);
381 (*p) -= byte_len;
382 memcpy(*p, buf, byte_len);
Andres Amaya Garciaec6329f2018-09-26 10:48:24 +0100383 }
384
385 /* Write unused bits */
Gilles Peskine449bd832023-01-11 14:50:10 +0100386 *--(*p) = (unsigned char) unused_bits;
Paul Bakker598e4502013-08-25 14:46:39 +0200387
Gilles Peskine449bd832023-01-11 14:50:10 +0100388 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
389 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_BIT_STRING));
Paul Bakker598e4502013-08-25 14:46:39 +0200390
Gilles Peskine449bd832023-01-11 14:50:10 +0100391 return (int) len;
Paul Bakker598e4502013-08-25 14:46:39 +0200392}
393
Gilles Peskine449bd832023-01-11 14:50:10 +0100394int mbedtls_asn1_write_octet_string(unsigned char **p, const unsigned char *start,
395 const unsigned char *buf, size_t size)
Paul Bakker598e4502013-08-25 14:46:39 +0200396{
Janos Follath24eed8d2019-11-22 13:21:35 +0000397 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
Paul Bakker598e4502013-08-25 14:46:39 +0200398 size_t len = 0;
399
Gilles Peskine449bd832023-01-11 14:50:10 +0100400 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, buf, size));
Paul Bakker598e4502013-08-25 14:46:39 +0200401
Gilles Peskine449bd832023-01-11 14:50:10 +0100402 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
403 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OCTET_STRING));
Paul Bakker598e4502013-08-25 14:46:39 +0200404
Gilles Peskine449bd832023-01-11 14:50:10 +0100405 return (int) len;
Paul Bakker598e4502013-08-25 14:46:39 +0200406}
Paul Bakker59ba59f2013-09-09 11:26:00 +0200407
Hanno Becker44da18a2018-10-12 10:42:13 +0100408
409/* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(),
410 * which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */
411static mbedtls_asn1_named_data *asn1_find_named_data(
Gilles Peskine449bd832023-01-11 14:50:10 +0100412 mbedtls_asn1_named_data *list,
413 const char *oid, size_t len)
Hanno Becker44da18a2018-10-12 10:42:13 +0100414{
Gilles Peskine449bd832023-01-11 14:50:10 +0100415 while (list != NULL) {
416 if (list->oid.len == len &&
417 memcmp(list->oid.p, oid, len) == 0) {
Hanno Becker44da18a2018-10-12 10:42:13 +0100418 break;
419 }
420
421 list = list->next;
422 }
423
Gilles Peskine449bd832023-01-11 14:50:10 +0100424 return list;
Hanno Becker44da18a2018-10-12 10:42:13 +0100425}
426
427mbedtls_asn1_named_data *mbedtls_asn1_store_named_data(
Gilles Peskine449bd832023-01-11 14:50:10 +0100428 mbedtls_asn1_named_data **head,
429 const char *oid, size_t oid_len,
430 const unsigned char *val,
431 size_t val_len)
Paul Bakker59ba59f2013-09-09 11:26:00 +0200432{
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200433 mbedtls_asn1_named_data *cur;
Paul Bakker59ba59f2013-09-09 11:26:00 +0200434
Gilles Peskine449bd832023-01-11 14:50:10 +0100435 if ((cur = asn1_find_named_data(*head, oid, oid_len)) == NULL) {
Paul Bakker59ba59f2013-09-09 11:26:00 +0200436 // Add new entry if not present yet based on OID
437 //
Gilles Peskine449bd832023-01-11 14:50:10 +0100438 cur = (mbedtls_asn1_named_data *) mbedtls_calloc(1,
439 sizeof(mbedtls_asn1_named_data));
440 if (cur == NULL) {
441 return NULL;
Paul Bakker59ba59f2013-09-09 11:26:00 +0200442 }
443
Gilles Peskine449bd832023-01-11 14:50:10 +0100444 cur->oid.len = oid_len;
445 cur->oid.p = mbedtls_calloc(1, oid_len);
446 if (cur->oid.p == NULL) {
447 mbedtls_free(cur);
448 return NULL;
449 }
450
451 memcpy(cur->oid.p, oid, oid_len);
Manuel Pégourié-Gonnarde5b0fc12014-11-12 22:27:42 +0100452
Paul Bakker59ba59f2013-09-09 11:26:00 +0200453 cur->val.len = val_len;
Gilles Peskine449bd832023-01-11 14:50:10 +0100454 if (val_len != 0) {
455 cur->val.p = mbedtls_calloc(1, val_len);
456 if (cur->val.p == NULL) {
457 mbedtls_free(cur->oid.p);
458 mbedtls_free(cur);
459 return NULL;
Gilles Peskine09c0a232019-03-04 15:00:06 +0100460 }
Paul Bakker59ba59f2013-09-09 11:26:00 +0200461 }
462
Paul Bakker59ba59f2013-09-09 11:26:00 +0200463 cur->next = *head;
464 *head = cur;
Gilles Peskine449bd832023-01-11 14:50:10 +0100465 } else if (val_len == 0) {
466 mbedtls_free(cur->val.p);
Gilles Peskine09c0a232019-03-04 15:00:06 +0100467 cur->val.p = NULL;
Gilles Peskine449bd832023-01-11 14:50:10 +0100468 } else if (cur->val.len != val_len) {
Manuel Pégourié-Gonnard97b52092015-12-10 10:50:51 +0100469 /*
470 * Enlarge existing value buffer if needed
471 * Preserve old data until the allocation succeeded, to leave list in
472 * a consistent state in case allocation fails.
473 */
Gilles Peskine449bd832023-01-11 14:50:10 +0100474 void *p = mbedtls_calloc(1, val_len);
475 if (p == NULL) {
476 return NULL;
477 }
Manuel Pégourié-Gonnard97b52092015-12-10 10:50:51 +0100478
Gilles Peskine449bd832023-01-11 14:50:10 +0100479 mbedtls_free(cur->val.p);
Manuel Pégourié-Gonnard97b52092015-12-10 10:50:51 +0100480 cur->val.p = p;
481 cur->val.len = val_len;
Paul Bakker59ba59f2013-09-09 11:26:00 +0200482 }
483
Gilles Peskine449bd832023-01-11 14:50:10 +0100484 if (val != NULL && val_len != 0) {
485 memcpy(cur->val.p, val, val_len);
486 }
Paul Bakker59ba59f2013-09-09 11:26:00 +0200487
Gilles Peskine449bd832023-01-11 14:50:10 +0100488 return cur;
Paul Bakker59ba59f2013-09-09 11:26:00 +0200489}
Manuel Pégourié-Gonnard2cf5a7c2015-04-08 12:49:31 +0200490#endif /* MBEDTLS_ASN1_WRITE_C */