276 lines
7.2 KiB
C
276 lines
7.2 KiB
C
/*
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* Copyright 2016-2021 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#ifdef OPENSSL_NO_CT
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# error "CT is disabled"
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#endif
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#include <stddef.h>
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#include <string.h>
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#include <openssl/err.h>
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#include <openssl/obj_mac.h>
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#include <openssl/x509.h>
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#include "ct_local.h"
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SCT_CTX *SCT_CTX_new(OSSL_LIB_CTX *libctx, const char *propq)
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{
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SCT_CTX *sctx = OPENSSL_zalloc(sizeof(*sctx));
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if (sctx == NULL)
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return NULL;
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sctx->libctx = libctx;
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if (propq != NULL) {
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sctx->propq = OPENSSL_strdup(propq);
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if (sctx->propq == NULL) {
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OPENSSL_free(sctx);
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return NULL;
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}
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}
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return sctx;
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}
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void SCT_CTX_free(SCT_CTX *sctx)
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{
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if (sctx == NULL)
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return;
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EVP_PKEY_free(sctx->pkey);
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OPENSSL_free(sctx->pkeyhash);
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OPENSSL_free(sctx->ihash);
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OPENSSL_free(sctx->certder);
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OPENSSL_free(sctx->preder);
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OPENSSL_free(sctx->propq);
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OPENSSL_free(sctx);
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}
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/*
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* Finds the index of the first extension with the given NID in cert.
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* If there is more than one extension with that NID, *is_duplicated is set to
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* 1, otherwise 0 (unless it is NULL).
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*/
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static int ct_x509_get_ext(X509 *cert, int nid, int *is_duplicated)
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{
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int ret = X509_get_ext_by_NID(cert, nid, -1);
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if (is_duplicated != NULL)
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*is_duplicated = ret >= 0 && X509_get_ext_by_NID(cert, nid, ret) >= 0;
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return ret;
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}
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/*
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* Modifies a certificate by deleting extensions and copying the issuer and
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* AKID from the presigner certificate, if necessary.
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* Returns 1 on success, 0 otherwise.
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*/
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__owur static int ct_x509_cert_fixup(X509 *cert, X509 *presigner)
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{
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int preidx, certidx;
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int pre_akid_ext_is_dup, cert_akid_ext_is_dup;
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if (presigner == NULL)
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return 1;
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preidx = ct_x509_get_ext(presigner, NID_authority_key_identifier,
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&pre_akid_ext_is_dup);
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certidx = ct_x509_get_ext(cert, NID_authority_key_identifier,
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&cert_akid_ext_is_dup);
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/* An error occurred whilst searching for the extension */
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if (preidx < -1 || certidx < -1)
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return 0;
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/* Invalid certificate if they contain duplicate extensions */
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if (pre_akid_ext_is_dup || cert_akid_ext_is_dup)
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return 0;
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/* AKID must be present in both certificate or absent in both */
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if (preidx >= 0 && certidx == -1)
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return 0;
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if (preidx == -1 && certidx >= 0)
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return 0;
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/* Copy issuer name */
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if (!X509_set_issuer_name(cert, X509_get_issuer_name(presigner)))
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return 0;
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if (preidx != -1) {
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/* Retrieve and copy AKID encoding */
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X509_EXTENSION *preext = X509_get_ext(presigner, preidx);
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X509_EXTENSION *certext = X509_get_ext(cert, certidx);
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ASN1_OCTET_STRING *preextdata;
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/* Should never happen */
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if (preext == NULL || certext == NULL)
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return 0;
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preextdata = X509_EXTENSION_get_data(preext);
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if (preextdata == NULL ||
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!X509_EXTENSION_set_data(certext, preextdata))
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return 0;
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}
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return 1;
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}
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int SCT_CTX_set1_cert(SCT_CTX *sctx, X509 *cert, X509 *presigner)
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{
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unsigned char *certder = NULL, *preder = NULL;
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X509 *pretmp = NULL;
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int certderlen = 0, prederlen = 0;
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int idx = -1;
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int poison_ext_is_dup, sct_ext_is_dup;
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int poison_idx = ct_x509_get_ext(cert, NID_ct_precert_poison, &poison_ext_is_dup);
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/* Duplicate poison extensions are present - error */
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if (poison_ext_is_dup)
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goto err;
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/* If *cert doesn't have a poison extension, it isn't a precert */
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if (poison_idx == -1) {
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/* cert isn't a precert, so we shouldn't have a presigner */
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if (presigner != NULL)
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goto err;
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certderlen = i2d_X509(cert, &certder);
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if (certderlen < 0)
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goto err;
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}
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/* See if cert has a precert SCTs extension */
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idx = ct_x509_get_ext(cert, NID_ct_precert_scts, &sct_ext_is_dup);
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/* Duplicate SCT extensions are present - error */
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if (sct_ext_is_dup)
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goto err;
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if (idx >= 0 && poison_idx >= 0) {
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/*
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* cert can't both contain SCTs (i.e. have an SCT extension) and be a
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* precert (i.e. have a poison extension).
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*/
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goto err;
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}
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if (idx == -1) {
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idx = poison_idx;
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}
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/*
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* If either a poison or SCT extension is present, remove it before encoding
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* cert. This, along with ct_x509_cert_fixup(), gets a TBSCertificate (see
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* RFC5280) from cert, which is what the CT log signed when it produced the
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* SCT.
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*/
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if (idx >= 0) {
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/* Take a copy of certificate so we don't modify passed version */
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pretmp = X509_dup(cert);
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if (pretmp == NULL)
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goto err;
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X509_EXTENSION_free(X509_delete_ext(pretmp, idx));
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if (!ct_x509_cert_fixup(pretmp, presigner))
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goto err;
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prederlen = i2d_re_X509_tbs(pretmp, &preder);
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if (prederlen <= 0)
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goto err;
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}
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X509_free(pretmp);
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OPENSSL_free(sctx->certder);
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sctx->certder = certder;
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sctx->certderlen = certderlen;
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OPENSSL_free(sctx->preder);
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sctx->preder = preder;
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sctx->prederlen = prederlen;
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return 1;
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err:
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OPENSSL_free(certder);
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OPENSSL_free(preder);
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X509_free(pretmp);
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return 0;
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}
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__owur static int ct_public_key_hash(SCT_CTX *sctx, X509_PUBKEY *pkey,
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unsigned char **hash, size_t *hash_len)
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{
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int ret = 0;
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unsigned char *md = NULL, *der = NULL;
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int der_len;
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unsigned int md_len;
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EVP_MD *sha256 = EVP_MD_fetch(sctx->libctx, "SHA2-256", sctx->propq);
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if (sha256 == NULL)
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goto err;
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/* Reuse buffer if possible */
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if (*hash != NULL && *hash_len >= SHA256_DIGEST_LENGTH) {
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md = *hash;
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} else {
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md = OPENSSL_malloc(SHA256_DIGEST_LENGTH);
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if (md == NULL)
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goto err;
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}
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/* Calculate key hash */
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der_len = i2d_X509_PUBKEY(pkey, &der);
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if (der_len <= 0)
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goto err;
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if (!EVP_Digest(der, der_len, md, &md_len, sha256, NULL))
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goto err;
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if (md != *hash) {
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OPENSSL_free(*hash);
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*hash = md;
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*hash_len = SHA256_DIGEST_LENGTH;
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}
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md = NULL;
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ret = 1;
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err:
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EVP_MD_free(sha256);
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OPENSSL_free(md);
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OPENSSL_free(der);
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return ret;
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}
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int SCT_CTX_set1_issuer(SCT_CTX *sctx, const X509 *issuer)
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{
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return SCT_CTX_set1_issuer_pubkey(sctx, X509_get_X509_PUBKEY(issuer));
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}
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int SCT_CTX_set1_issuer_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
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{
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return ct_public_key_hash(sctx, pubkey, &sctx->ihash, &sctx->ihashlen);
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}
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int SCT_CTX_set1_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
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{
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EVP_PKEY *pkey = X509_PUBKEY_get(pubkey);
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if (pkey == NULL)
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return 0;
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if (!ct_public_key_hash(sctx, pubkey, &sctx->pkeyhash, &sctx->pkeyhashlen)) {
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EVP_PKEY_free(pkey);
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return 0;
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}
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EVP_PKEY_free(sctx->pkey);
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sctx->pkey = pkey;
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return 1;
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}
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void SCT_CTX_set_time(SCT_CTX *sctx, uint64_t time_in_ms)
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{
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sctx->epoch_time_in_ms = time_in_ms;
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}
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