1 /*
2 * X.509 internal, common functions for writing
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 */
7 #include "common.h"
8 #if defined(MBEDTLS_X509_CSR_WRITE_C) || defined(MBEDTLS_X509_CRT_WRITE_C)
9
10 #include "mbedtls/x509_crt.h"
11 #include "mbedtls/asn1write.h"
12 #include "mbedtls/error.h"
13 #include "mbedtls/oid.h"
14 #include "mbedtls/platform.h"
15 #include "mbedtls/platform_util.h"
16 #include "mbedtls/md.h"
17
18 #include <string.h>
19 #include <stdint.h>
20
21 #if defined(MBEDTLS_PEM_WRITE_C)
22 #include "mbedtls/pem.h"
23 #endif /* MBEDTLS_PEM_WRITE_C */
24
25 #if defined(MBEDTLS_USE_PSA_CRYPTO)
26 #include "psa/crypto.h"
27 #include "mbedtls/psa_util.h"
28 #include "md_psa.h"
29 #endif /* MBEDTLS_USE_PSA_CRYPTO */
30
31 #define CHECK_OVERFLOW_ADD(a, b) \
32 do \
33 { \
34 if (a > SIZE_MAX - (b)) \
35 { \
36 return MBEDTLS_ERR_X509_BAD_INPUT_DATA; \
37 } \
38 a += b; \
39 } while (0)
40
mbedtls_x509_write_set_san_common(mbedtls_asn1_named_data ** extensions,const mbedtls_x509_san_list * san_list)41 int mbedtls_x509_write_set_san_common(mbedtls_asn1_named_data **extensions,
42 const mbedtls_x509_san_list *san_list)
43 {
44 int ret = 0;
45 const mbedtls_x509_san_list *cur;
46 unsigned char *buf;
47 unsigned char *p;
48 size_t len;
49 size_t buflen = 0;
50
51 /* Determine the maximum size of the SubjectAltName list */
52 for (cur = san_list; cur != NULL; cur = cur->next) {
53 /* Calculate size of the required buffer */
54 switch (cur->node.type) {
55 case MBEDTLS_X509_SAN_DNS_NAME:
56 case MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER:
57 case MBEDTLS_X509_SAN_IP_ADDRESS:
58 case MBEDTLS_X509_SAN_RFC822_NAME:
59 /* length of value for each name entry,
60 * maximum 4 bytes for the length field,
61 * 1 byte for the tag/type.
62 */
63 CHECK_OVERFLOW_ADD(buflen, cur->node.san.unstructured_name.len);
64 CHECK_OVERFLOW_ADD(buflen, 4 + 1);
65 break;
66 case MBEDTLS_X509_SAN_DIRECTORY_NAME:
67 {
68 const mbedtls_asn1_named_data *chunk = &cur->node.san.directory_name;
69 while (chunk != NULL) {
70 // Max 4 bytes for length, +1 for tag,
71 // additional 4 max for length, +1 for tag.
72 // See x509_write_name for more information.
73 CHECK_OVERFLOW_ADD(buflen, 4 + 1 + 4 + 1);
74 CHECK_OVERFLOW_ADD(buflen, chunk->oid.len);
75 CHECK_OVERFLOW_ADD(buflen, chunk->val.len);
76 chunk = chunk->next;
77 }
78 CHECK_OVERFLOW_ADD(buflen, 4 + 1);
79 break;
80 }
81 default:
82 /* Not supported - return. */
83 return MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE;
84 }
85 }
86
87 /* Add the extra length field and tag */
88 CHECK_OVERFLOW_ADD(buflen, 4 + 1);
89
90 /* Allocate buffer */
91 buf = mbedtls_calloc(1, buflen);
92 if (buf == NULL) {
93 return MBEDTLS_ERR_ASN1_ALLOC_FAILED;
94 }
95 p = buf + buflen;
96
97 /* Write ASN.1-based structure */
98 cur = san_list;
99 len = 0;
100 while (cur != NULL) {
101 size_t single_san_len = 0;
102 switch (cur->node.type) {
103 case MBEDTLS_X509_SAN_DNS_NAME:
104 case MBEDTLS_X509_SAN_RFC822_NAME:
105 case MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER:
106 case MBEDTLS_X509_SAN_IP_ADDRESS:
107 {
108 const unsigned char *unstructured_name =
109 (const unsigned char *) cur->node.san.unstructured_name.p;
110 size_t unstructured_name_len = cur->node.san.unstructured_name.len;
111
112 MBEDTLS_ASN1_CHK_CLEANUP_ADD(single_san_len,
113 mbedtls_asn1_write_raw_buffer(
114 &p, buf,
115 unstructured_name, unstructured_name_len));
116 MBEDTLS_ASN1_CHK_CLEANUP_ADD(single_san_len, mbedtls_asn1_write_len(
117 &p, buf, unstructured_name_len));
118 MBEDTLS_ASN1_CHK_CLEANUP_ADD(single_san_len,
119 mbedtls_asn1_write_tag(
120 &p, buf,
121 MBEDTLS_ASN1_CONTEXT_SPECIFIC | cur->node.type));
122 }
123 break;
124 case MBEDTLS_X509_SAN_DIRECTORY_NAME:
125 MBEDTLS_ASN1_CHK_CLEANUP_ADD(single_san_len,
126 mbedtls_x509_write_names(&p, buf,
127 (mbedtls_asn1_named_data *) &
128 cur->node
129 .san.directory_name));
130 MBEDTLS_ASN1_CHK_CLEANUP_ADD(single_san_len,
131 mbedtls_asn1_write_len(&p, buf, single_san_len));
132 MBEDTLS_ASN1_CHK_CLEANUP_ADD(single_san_len,
133 mbedtls_asn1_write_tag(&p, buf,
134 MBEDTLS_ASN1_CONTEXT_SPECIFIC |
135 MBEDTLS_ASN1_CONSTRUCTED |
136 MBEDTLS_X509_SAN_DIRECTORY_NAME));
137 break;
138 default:
139 /* Error out on an unsupported SAN */
140 ret = MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE;
141 goto cleanup;
142 }
143 cur = cur->next;
144 /* check for overflow */
145 if (len > SIZE_MAX - single_san_len) {
146 ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA;
147 goto cleanup;
148 }
149 len += single_san_len;
150 }
151
152 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len, mbedtls_asn1_write_len(&p, buf, len));
153 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
154 mbedtls_asn1_write_tag(&p, buf,
155 MBEDTLS_ASN1_CONSTRUCTED |
156 MBEDTLS_ASN1_SEQUENCE));
157
158 ret = mbedtls_x509_set_extension(extensions,
159 MBEDTLS_OID_SUBJECT_ALT_NAME,
160 MBEDTLS_OID_SIZE(MBEDTLS_OID_SUBJECT_ALT_NAME),
161 0,
162 buf + buflen - len, len);
163
164 /* If we exceeded the allocated buffer it means that maximum size of the SubjectAltName list
165 * was incorrectly calculated and memory is corrupted. */
166 if (p < buf) {
167 ret = MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
168 }
169 cleanup:
170 mbedtls_free(buf);
171 return ret;
172 }
173
174 #endif /* MBEDTLS_X509_CSR_WRITE_C || MBEDTLS_X509_CRT_WRITE_C */
175
