1 /*
2 * Copyright 2016-2021 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
SCT_CTX_new(OSSL_LIB_CTX * libctx,const char * propq)23 SCT_CTX *SCT_CTX_new(OSSL_LIB_CTX *libctx, const char *propq)
24 {
25 SCT_CTX *sctx = OPENSSL_zalloc(sizeof(*sctx));
26
27 if (sctx == NULL) {
28 ERR_raise(ERR_LIB_CT, ERR_R_MALLOC_FAILURE);
29 return NULL;
30 }
31
32 sctx->libctx = libctx;
33 if (propq != NULL) {
34 sctx->propq = OPENSSL_strdup(propq);
35 if (sctx->propq == NULL) {
36 ERR_raise(ERR_LIB_CT, ERR_R_MALLOC_FAILURE);
37 OPENSSL_free(sctx);
38 return NULL;
39 }
40 }
41
42 return sctx;
43 }
44
SCT_CTX_free(SCT_CTX * sctx)45 void SCT_CTX_free(SCT_CTX *sctx)
46 {
47 if (sctx == NULL)
48 return;
49 EVP_PKEY_free(sctx->pkey);
50 OPENSSL_free(sctx->pkeyhash);
51 OPENSSL_free(sctx->ihash);
52 OPENSSL_free(sctx->certder);
53 OPENSSL_free(sctx->preder);
54 OPENSSL_free(sctx->propq);
55 OPENSSL_free(sctx);
56 }
57
58 /*
59 * Finds the index of the first extension with the given NID in cert.
60 * If there is more than one extension with that NID, *is_duplicated is set to
61 * 1, otherwise 0 (unless it is NULL).
62 */
ct_x509_get_ext(X509 * cert,int nid,int * is_duplicated)63 static int ct_x509_get_ext(X509 *cert, int nid, int *is_duplicated)
64 {
65 int ret = X509_get_ext_by_NID(cert, nid, -1);
66
67 if (is_duplicated != NULL)
68 *is_duplicated = ret >= 0 && X509_get_ext_by_NID(cert, nid, ret) >= 0;
69
70 return ret;
71 }
72
73 /*
74 * Modifies a certificate by deleting extensions and copying the issuer and
75 * AKID from the presigner certificate, if necessary.
76 * Returns 1 on success, 0 otherwise.
77 */
ct_x509_cert_fixup(X509 * cert,X509 * presigner)78 __owur static int ct_x509_cert_fixup(X509 *cert, X509 *presigner)
79 {
80 int preidx, certidx;
81 int pre_akid_ext_is_dup, cert_akid_ext_is_dup;
82
83 if (presigner == NULL)
84 return 1;
85
86 preidx = ct_x509_get_ext(presigner, NID_authority_key_identifier,
87 &pre_akid_ext_is_dup);
88 certidx = ct_x509_get_ext(cert, NID_authority_key_identifier,
89 &cert_akid_ext_is_dup);
90
91 /* An error occurred whilst searching for the extension */
92 if (preidx < -1 || certidx < -1)
93 return 0;
94 /* Invalid certificate if they contain duplicate extensions */
95 if (pre_akid_ext_is_dup || cert_akid_ext_is_dup)
96 return 0;
97 /* AKID must be present in both certificate or absent in both */
98 if (preidx >= 0 && certidx == -1)
99 return 0;
100 if (preidx == -1 && certidx >= 0)
101 return 0;
102 /* Copy issuer name */
103 if (!X509_set_issuer_name(cert, X509_get_issuer_name(presigner)))
104 return 0;
105 if (preidx != -1) {
106 /* Retrieve and copy AKID encoding */
107 X509_EXTENSION *preext = X509_get_ext(presigner, preidx);
108 X509_EXTENSION *certext = X509_get_ext(cert, certidx);
109 ASN1_OCTET_STRING *preextdata;
110
111 /* Should never happen */
112 if (preext == NULL || certext == NULL)
113 return 0;
114 preextdata = X509_EXTENSION_get_data(preext);
115 if (preextdata == NULL ||
116 !X509_EXTENSION_set_data(certext, preextdata))
117 return 0;
118 }
119 return 1;
120 }
121
SCT_CTX_set1_cert(SCT_CTX * sctx,X509 * cert,X509 * presigner)122 int SCT_CTX_set1_cert(SCT_CTX *sctx, X509 *cert, X509 *presigner)
123 {
124 unsigned char *certder = NULL, *preder = NULL;
125 X509 *pretmp = NULL;
126 int certderlen = 0, prederlen = 0;
127 int idx = -1;
128 int poison_ext_is_dup, sct_ext_is_dup;
129 int poison_idx = ct_x509_get_ext(cert, NID_ct_precert_poison, &poison_ext_is_dup);
130
131 /* Duplicate poison extensions are present - error */
132 if (poison_ext_is_dup)
133 goto err;
134
135 /* If *cert doesn't have a poison extension, it isn't a precert */
136 if (poison_idx == -1) {
137 /* cert isn't a precert, so we shouldn't have a presigner */
138 if (presigner != NULL)
139 goto err;
140
141 certderlen = i2d_X509(cert, &certder);
142 if (certderlen < 0)
143 goto err;
144 }
145
146 /* See if cert has a precert SCTs extension */
147 idx = ct_x509_get_ext(cert, NID_ct_precert_scts, &sct_ext_is_dup);
148 /* Duplicate SCT extensions are present - error */
149 if (sct_ext_is_dup)
150 goto err;
151
152 if (idx >= 0 && poison_idx >= 0) {
153 /*
154 * cert can't both contain SCTs (i.e. have an SCT extension) and be a
155 * precert (i.e. have a poison extension).
156 */
157 goto err;
158 }
159
160 if (idx == -1) {
161 idx = poison_idx;
162 }
163
164 /*
165 * If either a poison or SCT extension is present, remove it before encoding
166 * cert. This, along with ct_x509_cert_fixup(), gets a TBSCertificate (see
167 * RFC5280) from cert, which is what the CT log signed when it produced the
168 * SCT.
169 */
170 if (idx >= 0) {
171 /* Take a copy of certificate so we don't modify passed version */
172 pretmp = X509_dup(cert);
173 if (pretmp == NULL)
174 goto err;
175
176 X509_EXTENSION_free(X509_delete_ext(pretmp, idx));
177
178 if (!ct_x509_cert_fixup(pretmp, presigner))
179 goto err;
180
181 prederlen = i2d_re_X509_tbs(pretmp, &preder);
182 if (prederlen <= 0)
183 goto err;
184 }
185
186 X509_free(pretmp);
187
188 OPENSSL_free(sctx->certder);
189 sctx->certder = certder;
190 sctx->certderlen = certderlen;
191
192 OPENSSL_free(sctx->preder);
193 sctx->preder = preder;
194 sctx->prederlen = prederlen;
195
196 return 1;
197 err:
198 OPENSSL_free(certder);
199 OPENSSL_free(preder);
200 X509_free(pretmp);
201 return 0;
202 }
203
ct_public_key_hash(SCT_CTX * sctx,X509_PUBKEY * pkey,unsigned char ** hash,size_t * hash_len)204 __owur static int ct_public_key_hash(SCT_CTX *sctx, X509_PUBKEY *pkey,
205 unsigned char **hash, size_t *hash_len)
206 {
207 int ret = 0;
208 unsigned char *md = NULL, *der = NULL;
209 int der_len;
210 unsigned int md_len;
211 EVP_MD *sha256 = EVP_MD_fetch(sctx->libctx, "SHA2-256", sctx->propq);
212
213 if (sha256 == NULL)
214 goto err;
215
216 /* Reuse buffer if possible */
217 if (*hash != NULL && *hash_len >= SHA256_DIGEST_LENGTH) {
218 md = *hash;
219 } else {
220 md = OPENSSL_malloc(SHA256_DIGEST_LENGTH);
221 if (md == NULL)
222 goto err;
223 }
224
225 /* Calculate key hash */
226 der_len = i2d_X509_PUBKEY(pkey, &der);
227 if (der_len <= 0)
228 goto err;
229
230 if (!EVP_Digest(der, der_len, md, &md_len, sha256, NULL))
231 goto err;
232
233 if (md != *hash) {
234 OPENSSL_free(*hash);
235 *hash = md;
236 *hash_len = SHA256_DIGEST_LENGTH;
237 }
238
239 md = NULL;
240 ret = 1;
241 err:
242 EVP_MD_free(sha256);
243 OPENSSL_free(md);
244 OPENSSL_free(der);
245 return ret;
246 }
247
SCT_CTX_set1_issuer(SCT_CTX * sctx,const X509 * issuer)248 int SCT_CTX_set1_issuer(SCT_CTX *sctx, const X509 *issuer)
249 {
250 return SCT_CTX_set1_issuer_pubkey(sctx, X509_get_X509_PUBKEY(issuer));
251 }
252
SCT_CTX_set1_issuer_pubkey(SCT_CTX * sctx,X509_PUBKEY * pubkey)253 int SCT_CTX_set1_issuer_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
254 {
255 return ct_public_key_hash(sctx, pubkey, &sctx->ihash, &sctx->ihashlen);
256 }
257
SCT_CTX_set1_pubkey(SCT_CTX * sctx,X509_PUBKEY * pubkey)258 int SCT_CTX_set1_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
259 {
260 EVP_PKEY *pkey = X509_PUBKEY_get(pubkey);
261
262 if (pkey == NULL)
263 return 0;
264
265 if (!ct_public_key_hash(sctx, pubkey, &sctx->pkeyhash, &sctx->pkeyhashlen)) {
266 EVP_PKEY_free(pkey);
267 return 0;
268 }
269
270 EVP_PKEY_free(sctx->pkey);
271 sctx->pkey = pkey;
272 return 1;
273 }
274
SCT_CTX_set_time(SCT_CTX * sctx,uint64_t time_in_ms)275 void SCT_CTX_set_time(SCT_CTX *sctx, uint64_t time_in_ms)
276 {
277 sctx->epoch_time_in_ms = time_in_ms;
278 }
279