1/*
2 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#ifdef OPENSSL_NO_CT
11# error "CT is disabled"
12#endif
13
14#include <stddef.h>
15#include <string.h>
16
17#include <openssl/err.h>
18#include <openssl/obj_mac.h>
19#include <openssl/x509.h>
20
21#include "ct_local.h"
22
23SCT_CTX *SCT_CTX_new(void)
24{
25 SCT_CTX *sctx = OPENSSL_zalloc(sizeof(*sctx));
26
27 if (sctx == NULL)
28 CTerr(CT_F_SCT_CTX_NEW, ERR_R_MALLOC_FAILURE);
29
30 return sctx;
31}
32
33void SCT_CTX_free(SCT_CTX *sctx)
34{
35 if (sctx == NULL)
36 return;
37 EVP_PKEY_free(sctx->pkey);
38 OPENSSL_free(sctx->pkeyhash);
39 OPENSSL_free(sctx->ihash);
40 OPENSSL_free(sctx->certder);
41 OPENSSL_free(sctx->preder);
42 OPENSSL_free(sctx);
43}
44
45/*
46 * Finds the index of the first extension with the given NID in cert.
47 * If there is more than one extension with that NID, *is_duplicated is set to
48 * 1, otherwise 0 (unless it is NULL).
49 */
50static int ct_x509_get_ext(X509 *cert, int nid, int *is_duplicated)
51{
52 int ret = X509_get_ext_by_NID(cert, nid, -1);
53
54 if (is_duplicated != NULL)
55 *is_duplicated = ret >= 0 && X509_get_ext_by_NID(cert, nid, ret) >= 0;
56
57 return ret;
58}
59
60/*
61 * Modifies a certificate by deleting extensions and copying the issuer and
62 * AKID from the presigner certificate, if necessary.
63 * Returns 1 on success, 0 otherwise.
64 */
65__owur static int ct_x509_cert_fixup(X509 *cert, X509 *presigner)
66{
67 int preidx, certidx;
68 int pre_akid_ext_is_dup, cert_akid_ext_is_dup;
69
70 if (presigner == NULL)
71 return 1;
72
73 preidx = ct_x509_get_ext(presigner, NID_authority_key_identifier,
74 &pre_akid_ext_is_dup);
75 certidx = ct_x509_get_ext(cert, NID_authority_key_identifier,
76 &cert_akid_ext_is_dup);
77
78 /* An error occurred whilst searching for the extension */
79 if (preidx < -1 || certidx < -1)
80 return 0;
81 /* Invalid certificate if they contain duplicate extensions */
82 if (pre_akid_ext_is_dup || cert_akid_ext_is_dup)
83 return 0;
84 /* AKID must be present in both certificate or absent in both */
85 if (preidx >= 0 && certidx == -1)
86 return 0;
87 if (preidx == -1 && certidx >= 0)
88 return 0;
89 /* Copy issuer name */
90 if (!X509_set_issuer_name(cert, X509_get_issuer_name(presigner)))
91 return 0;
92 if (preidx != -1) {
93 /* Retrieve and copy AKID encoding */
94 X509_EXTENSION *preext = X509_get_ext(presigner, preidx);
95 X509_EXTENSION *certext = X509_get_ext(cert, certidx);
96 ASN1_OCTET_STRING *preextdata;
97
98 /* Should never happen */
99 if (preext == NULL || certext == NULL)
100 return 0;
101 preextdata = X509_EXTENSION_get_data(preext);
102 if (preextdata == NULL ||
103 !X509_EXTENSION_set_data(certext, preextdata))
104 return 0;
105 }
106 return 1;
107}
108
109int SCT_CTX_set1_cert(SCT_CTX *sctx, X509 *cert, X509 *presigner)
110{
111 unsigned char *certder = NULL, *preder = NULL;
112 X509 *pretmp = NULL;
113 int certderlen = 0, prederlen = 0;
114 int idx = -1;
115 int poison_ext_is_dup, sct_ext_is_dup;
116 int poison_idx = ct_x509_get_ext(cert, NID_ct_precert_poison, &poison_ext_is_dup);
117
118 /* Duplicate poison extensions are present - error */
119 if (poison_ext_is_dup)
120 goto err;
121
122 /* If *cert doesn't have a poison extension, it isn't a precert */
123 if (poison_idx == -1) {
124 /* cert isn't a precert, so we shouldn't have a presigner */
125 if (presigner != NULL)
126 goto err;
127
128 certderlen = i2d_X509(cert, &certder);
129 if (certderlen < 0)
130 goto err;
131 }
132
133 /* See if cert has a precert SCTs extension */
134 idx = ct_x509_get_ext(cert, NID_ct_precert_scts, &sct_ext_is_dup);
135 /* Duplicate SCT extensions are present - error */
136 if (sct_ext_is_dup)
137 goto err;
138
139 if (idx >= 0 && poison_idx >= 0) {
140 /*
141 * cert can't both contain SCTs (i.e. have an SCT extension) and be a
142 * precert (i.e. have a poison extension).
143 */
144 goto err;
145 }
146
147 if (idx == -1) {
148 idx = poison_idx;
149 }
150
151 /*
152 * If either a poison or SCT extension is present, remove it before encoding
153 * cert. This, along with ct_x509_cert_fixup(), gets a TBSCertificate (see
154 * RFC5280) from cert, which is what the CT log signed when it produced the
155 * SCT.
156 */
157 if (idx >= 0) {
158 X509_EXTENSION *ext;
159
160 /* Take a copy of certificate so we don't modify passed version */
161 pretmp = X509_dup(cert);
162 if (pretmp == NULL)
163 goto err;
164
165 ext = X509_delete_ext(pretmp, idx);
166 X509_EXTENSION_free(ext);
167
168 if (!ct_x509_cert_fixup(pretmp, presigner))
169 goto err;
170
171 prederlen = i2d_re_X509_tbs(pretmp, &preder);
172 if (prederlen <= 0)
173 goto err;
174 }
175
176 X509_free(pretmp);
177
178 OPENSSL_free(sctx->certder);
179 sctx->certder = certder;
180 sctx->certderlen = certderlen;
181
182 OPENSSL_free(sctx->preder);
183 sctx->preder = preder;
184 sctx->prederlen = prederlen;
185
186 return 1;
187err:
188 OPENSSL_free(certder);
189 OPENSSL_free(preder);
190 X509_free(pretmp);
191 return 0;
192}
193
194__owur static int ct_public_key_hash(X509_PUBKEY *pkey, unsigned char **hash,
195 size_t *hash_len)
196{
197 int ret = 0;
198 unsigned char *md = NULL, *der = NULL;
199 int der_len;
200 unsigned int md_len;
201
202 /* Reuse buffer if possible */
203 if (*hash != NULL && *hash_len >= SHA256_DIGEST_LENGTH) {
204 md = *hash;
205 } else {
206 md = OPENSSL_malloc(SHA256_DIGEST_LENGTH);
207 if (md == NULL)
208 goto err;
209 }
210
211 /* Calculate key hash */
212 der_len = i2d_X509_PUBKEY(pkey, &der);
213 if (der_len <= 0)
214 goto err;
215
216 if (!EVP_Digest(der, der_len, md, &md_len, EVP_sha256(), NULL))
217 goto err;
218
219 if (md != *hash) {
220 OPENSSL_free(*hash);
221 *hash = md;
222 *hash_len = SHA256_DIGEST_LENGTH;
223 }
224
225 md = NULL;
226 ret = 1;
227 err:
228 OPENSSL_free(md);
229 OPENSSL_free(der);
230 return ret;
231}
232
233int SCT_CTX_set1_issuer(SCT_CTX *sctx, const X509 *issuer)
234{
235 return SCT_CTX_set1_issuer_pubkey(sctx, X509_get_X509_PUBKEY(issuer));
236}
237
238int SCT_CTX_set1_issuer_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
239{
240 return ct_public_key_hash(pubkey, &sctx->ihash, &sctx->ihashlen);
241}
242
243int SCT_CTX_set1_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
244{
245 EVP_PKEY *pkey = X509_PUBKEY_get(pubkey);
246
247 if (pkey == NULL)
248 return 0;
249
250 if (!ct_public_key_hash(pubkey, &sctx->pkeyhash, &sctx->pkeyhashlen)) {
251 EVP_PKEY_free(pkey);
252 return 0;
253 }
254
255 EVP_PKEY_free(sctx->pkey);
256 sctx->pkey = pkey;
257 return 1;
258}
259
260void SCT_CTX_set_time(SCT_CTX *sctx, uint64_t time_in_ms)
261{
262 sctx->epoch_time_in_ms = time_in_ms;
263}
264