diff options
Diffstat (limited to 'crypto/ct/ct_sct_ctx.c')
| -rw-r--r-- | crypto/ct/ct_sct_ctx.c | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/crypto/ct/ct_sct_ctx.c b/crypto/ct/ct_sct_ctx.c new file mode 100644 index 000000000000..75a5027df0e8 --- /dev/null +++ b/crypto/ct/ct_sct_ctx.c @@ -0,0 +1,263 @@ +/* + * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved. + * + * Licensed under the OpenSSL license (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html + */ + +#ifdef OPENSSL_NO_CT +# error "CT is disabled" +#endif + +#include <stddef.h> +#include <string.h> + +#include <openssl/err.h> +#include <openssl/obj_mac.h> +#include <openssl/x509.h> + +#include "ct_locl.h" + +SCT_CTX *SCT_CTX_new(void) +{ + SCT_CTX *sctx = OPENSSL_zalloc(sizeof(*sctx)); + + if (sctx == NULL) + CTerr(CT_F_SCT_CTX_NEW, ERR_R_MALLOC_FAILURE); + + return sctx; +} + +void SCT_CTX_free(SCT_CTX *sctx) +{ + if (sctx == NULL) + return; + EVP_PKEY_free(sctx->pkey); + OPENSSL_free(sctx->pkeyhash); + OPENSSL_free(sctx->ihash); + OPENSSL_free(sctx->certder); + OPENSSL_free(sctx->preder); + OPENSSL_free(sctx); +} + +/* + * Finds the index of the first extension with the given NID in cert. + * If there is more than one extension with that NID, *is_duplicated is set to + * 1, otherwise 0 (unless it is NULL). + */ +static int ct_x509_get_ext(X509 *cert, int nid, int *is_duplicated) +{ + int ret = X509_get_ext_by_NID(cert, nid, -1); + + if (is_duplicated != NULL) + *is_duplicated = ret >= 0 && X509_get_ext_by_NID(cert, nid, ret) >= 0; + + return ret; +} + +/* + * Modifies a certificate by deleting extensions and copying the issuer and + * AKID from the presigner certificate, if necessary. + * Returns 1 on success, 0 otherwise. + */ +__owur static int ct_x509_cert_fixup(X509 *cert, X509 *presigner) +{ + int preidx, certidx; + int pre_akid_ext_is_dup, cert_akid_ext_is_dup; + + if (presigner == NULL) + return 1; + + preidx = ct_x509_get_ext(presigner, NID_authority_key_identifier, + &pre_akid_ext_is_dup); + certidx = ct_x509_get_ext(cert, NID_authority_key_identifier, + &cert_akid_ext_is_dup); + + /* An error occurred whilst searching for the extension */ + if (preidx < -1 || certidx < -1) + return 0; + /* Invalid certificate if they contain duplicate extensions */ + if (pre_akid_ext_is_dup || cert_akid_ext_is_dup) + return 0; + /* AKID must be present in both certificate or absent in both */ + if (preidx >= 0 && certidx == -1) + return 0; + if (preidx == -1 && certidx >= 0) + return 0; + /* Copy issuer name */ + if (!X509_set_issuer_name(cert, X509_get_issuer_name(presigner))) + return 0; + if (preidx != -1) { + /* Retrieve and copy AKID encoding */ + X509_EXTENSION *preext = X509_get_ext(presigner, preidx); + X509_EXTENSION *certext = X509_get_ext(cert, certidx); + ASN1_OCTET_STRING *preextdata; + + /* Should never happen */ + if (preext == NULL || certext == NULL) + return 0; + preextdata = X509_EXTENSION_get_data(preext); + if (preextdata == NULL || + !X509_EXTENSION_set_data(certext, preextdata)) + return 0; + } + return 1; +} + +int SCT_CTX_set1_cert(SCT_CTX *sctx, X509 *cert, X509 *presigner) +{ + unsigned char *certder = NULL, *preder = NULL; + X509 *pretmp = NULL; + int certderlen = 0, prederlen = 0; + int idx = -1; + int poison_ext_is_dup, sct_ext_is_dup; + int poison_idx = ct_x509_get_ext(cert, NID_ct_precert_poison, &poison_ext_is_dup); + + /* Duplicate poison extensions are present - error */ + if (poison_ext_is_dup) + goto err; + + /* If *cert doesn't have a poison extension, it isn't a precert */ + if (poison_idx == -1) { + /* cert isn't a precert, so we shouldn't have a presigner */ + if (presigner != NULL) + goto err; + + certderlen = i2d_X509(cert, &certder); + if (certderlen < 0) + goto err; + } + + /* See if cert has a precert SCTs extension */ + idx = ct_x509_get_ext(cert, NID_ct_precert_scts, &sct_ext_is_dup); + /* Duplicate SCT extensions are present - error */ + if (sct_ext_is_dup) + goto err; + + if (idx >= 0 && poison_idx >= 0) { + /* + * cert can't both contain SCTs (i.e. have an SCT extension) and be a + * precert (i.e. have a poison extension). + */ + goto err; + } + + if (idx == -1) { + idx = poison_idx; + } + + /* + * If either a poison or SCT extension is present, remove it before encoding + * cert. This, along with ct_x509_cert_fixup(), gets a TBSCertificate (see + * RFC5280) from cert, which is what the CT log signed when it produced the + * SCT. + */ + if (idx >= 0) { + X509_EXTENSION *ext; + + /* Take a copy of certificate so we don't modify passed version */ + pretmp = X509_dup(cert); + if (pretmp == NULL) + goto err; + + ext = X509_delete_ext(pretmp, idx); + X509_EXTENSION_free(ext); + + if (!ct_x509_cert_fixup(pretmp, presigner)) + goto err; + + prederlen = i2d_re_X509_tbs(pretmp, &preder); + if (prederlen <= 0) + goto err; + } + + X509_free(pretmp); + + OPENSSL_free(sctx->certder); + sctx->certder = certder; + sctx->certderlen = certderlen; + + OPENSSL_free(sctx->preder); + sctx->preder = preder; + sctx->prederlen = prederlen; + + return 1; +err: + OPENSSL_free(certder); + OPENSSL_free(preder); + X509_free(pretmp); + return 0; +} + +__owur static int ct_public_key_hash(X509_PUBKEY *pkey, unsigned char **hash, + size_t *hash_len) +{ + int ret = 0; + unsigned char *md = NULL, *der = NULL; + int der_len; + unsigned int md_len; + + /* Reuse buffer if possible */ + if (*hash != NULL && *hash_len >= SHA256_DIGEST_LENGTH) { + md = *hash; + } else { + md = OPENSSL_malloc(SHA256_DIGEST_LENGTH); + if (md == NULL) + goto err; + } + + /* Calculate key hash */ + der_len = i2d_X509_PUBKEY(pkey, &der); + if (der_len <= 0) + goto err; + + if (!EVP_Digest(der, der_len, md, &md_len, EVP_sha256(), NULL)) + goto err; + + if (md != *hash) { + OPENSSL_free(*hash); + *hash = md; + *hash_len = SHA256_DIGEST_LENGTH; + } + + md = NULL; + ret = 1; + err: + OPENSSL_free(md); + OPENSSL_free(der); + return ret; +} + +int SCT_CTX_set1_issuer(SCT_CTX *sctx, const X509 *issuer) +{ + return SCT_CTX_set1_issuer_pubkey(sctx, X509_get_X509_PUBKEY(issuer)); +} + +int SCT_CTX_set1_issuer_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey) +{ + return ct_public_key_hash(pubkey, &sctx->ihash, &sctx->ihashlen); +} + +int SCT_CTX_set1_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey) +{ + EVP_PKEY *pkey = X509_PUBKEY_get(pubkey); + + if (pkey == NULL) + return 0; + + if (!ct_public_key_hash(pubkey, &sctx->pkeyhash, &sctx->pkeyhashlen)) { + EVP_PKEY_free(pkey); + return 0; + } + + EVP_PKEY_free(sctx->pkey); + sctx->pkey = pkey; + return 1; +} + +void SCT_CTX_set_time(SCT_CTX *sctx, uint64_t time_in_ms) +{ + sctx->epoch_time_in_ms = time_in_ms; +} |