1 files changed, 263 insertions, 0 deletions

diff --git a/src/lib/libcrypto/ct/ct_sct_ctx.c b/src/lib/libcrypto/ct/ct_sct_ctx.c
new file mode 100644
index 0000000000..841e768033
--- /dev/null
+++ b/src/lib/libcrypto/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_local.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;
+}